International Journal of Powder Metallurgy Volume 44 Issue 1

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EDITORIAL REVIEW COMMITTEE P.W. Taubenblat, Chairman I.E. Anderson, FAPMI T. Ando S.G. Caldwell S.C. Deevi D. Dombrowski J.J. Dunkley Z. Fang B.L. Ferguson W. Frazier K. Kulkarni, FAPMI K.S. Kumar T.F. Murphy J.W. Newkirk P.D. Nurthen J.H. Perepezko P.K. Samal H.I. Sanderow D.W. Smith, FAPMI R. Tandon T.A. Tomlin D.T. Whychell, Sr., FAPMI M. Wright, PMT A. Zavaliangos INTERNATIONAL LIAISON COMMITTEE D. Whittaker (UK) Chairman V. Arnhold (Germany) E.C. Barba (Mexico) P. Beiss (Germany) C. Blais (Canada) P. Blanchard (France) G.F. Bocchini (Italy) F. Chagnon (Canada) C-L Chu (Taiwan) H. Danninger (Austria) U. Engström (Sweden) N.O. Grinder (Sweden) S. Guo (China) F-L Han (China) K.S. Hwang (Taiwan) Y.D. Kim (Korea) G. Kneringer (Austria) G. L’Espérance, FAPMI (Canada) H. Miura (Japan) C.B. Molins (Spain) R.L. Orban (Romania) T.L. Pecanha (Brazil) F. Petzoldt (Germany) S. Saritas (Turkey) G.B. Schaffer (Australia) Y. Takeda (Japan) G.S. Upadhyaya (India) Publisher C. James Trombino, CAE [email protected] Editor-in-Chief Alan Lawley, FAPMI [email protected] Managing Editor Peter K. Johnson [email protected] Advertising Manager Jessica S. Tamasi [email protected] Copy Editor Donni Magid [email protected] Production Assistant Dora Schember [email protected] President of APMI International Nicholas T. Mares [email protected] Executive Director/CEO, APMI International C. James Trombino, CAE [email protected]

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international journal of

powder metallurgy Contents 2 5 7 9

44/1 January/February 2008

Editor's Note PM Industry News in Review PMT Spotlight On … David Rector Consultants’ Corner James G. Marsden, FAPMI

GLOBAL REVIEW 15 Powder Metallurgy in Italy O. Morandi and E. Mosca

RESEARCH & DEVELOPMENT 22 Effect of Die Filling on Powder Compaction D. Korachkin, D.T. Gethin, R.W. Lewis and J.H. Tweed

35 High-Density Inconel 718: Three-Dimensional Printing Coupled with Hot Isostatic Pressing J. Sicre-Artalejo, F. Petzoldt, M. Campos and J.M. Torralba

ENGINEERING & TECHNOLOGY 44 Economics of Processing Nanoscale Powders J.L. Johnson

OUTSTANDING TECHNICAL PAPER FROM POWDERMET2007 55 Close-Coupled Gas Atomization: High-Frame-Rate Analysis of Spray-Cone Geometry A.M. Mullis, N.J.E. Adkins, Z. Aslam, I. McCarthy and R.F. Cochrane

65 78 79 80

DEPARTMENTS Web Site Directory Meetings and Conferences APMI Membership Application Advertisers’ Index Cover: Award of Distinction–winning parts from MPIF’s 2007 Design Excellence Awards Competition

The International Journal of Powder Metallurgy (ISSN No. 0888-7462) is a professional publication serving the scientific and technological needs and interests of the powder metallurgist and the metal powder producing and consuming industries. Advertising carried in the Journal is selected so as to meet these needs and interests. Unrelated advertising cannot be accepted. Published bimonthly by APMI International, 105 College Road East, Princeton, N.J. 08540-6692 USA. Telephone (609) 4527700. Periodical postage paid at Princeton, New Jersey, and at additional mailing offices. Copyright © 2008 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $95.00 individuals, $220.00 institutions; overseas: additional $40.00 postage; single issues $50.00. Printed in USA by Cadmus Communications Corporation, P.O. Box 27367, Richmond, Virginia 23261-7367. Postmaster send address changes to the International Journal of Powder Metallurgy, 105 College Road East, Princeton, New Jersey 08540 USA USPS#267-120 ADVERTISING INFORMATION Jessica Tamasi, APMI International INTERNATIONAL 105 College Road East, Princeton, New Jersey 08540-6692 USA Tel: (609) 452-7700 • Fax: (609) 987-8523 • E-mail: [email protected]

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EDITOR’S NOTE

N

ow in its 15th year, the MPIF Outstanding Technical Paper award recognizes excellence in scientific/technical content and written communication. Selected from the PowderMet2007 technical program, the recipients are from the University of Leeds and CERAM Research in the UK. Their collaborative study of close-coupled gas atomization, utilizing high-speed digital imaging to monitor and analyze the spray-cone geometry, establishes an improved understanding of the complex interactions between the gas and liquid-metal stream in atomization. In recognition of 2008 as a “World Congress” year, the Journal will publish a number of global PM reviews. The first of these, prepared by Morandi and Mosca, highlights the characteristics, history, and evolution of the PM industry in Italy, including a perspective on the future. There are two R&D contributions to this issue of the Journal. Korachkin et al. describe a numerical simulation study of the effect of variations in die-fill density on the final green-density distribution in a pressed part, and the attendant effect on tool stresses—both of prime importance to PM parts manufacturers. In the other study, Sicre-Artalejo et al. assess the feasibility of fabricating high-density parts from Inconel 718 powder utilizing three-dimensional printing. It is demonstrated that full density can be achieved by sintering and hot isostatic pressing of the printed parts. In the “Engineering & Technology” section, Johnson extends the sintering and property models for nanoscale tungsten to other nanoscale metal and ceramic powders in order to explore processing economics. His analysis, based on cost normalizing of properties, leads to the conclusion that the incremental improvement in performance, compared with that of conventional metal and ceramic powders, does not compensate for their higher cost. Usage of nanoscale powders in “press and sinter” processing mandates a lower powder cost and/or enhanced property performance. Returning to the “Consultants’ Corner,” Jim Marsden provides counsel on readers’ questions on sintering practice. In particular, his responses focus on the importance of the furnace presinter temperature profile in the delubrication of PM parts, and on-site generation of nitrogen–hydrogen sintering atmospheres. First published in 2001, the PM Web Site Directory continues to expand as e-business has become integral to the industry. This year’s directory classifies company entries by equipment manufacturers, metal powder producers, MIM/PIM, and others which includes PM consultants.

Alan Lawley Editor-in-Chief

In late 2007, I took the opportunity to attend the workshop on “REACH” (Registration, Evaluation, Authorization and Restriction of CHemicals), a major initiative designed to overhaul the European Union’s chemical management regime. Impetus for the new legislation reflects ever-increasing concerns for the protection of human health and the environment. Organized by MPIF and EPMA, the workshop provided an in-depth analysis of the EU regulation, including registration, testing and data requirements, substance identification, key dates, information sources, and its effect on North American PM companies exporting to the EU. Aptly titled “Are You Ready for REACH in North America?”, the workshop clearly identified the technical, legal, and financial impact and attendant challenge of REACH. It was also apparent to me that, among the powder producers at the workshop, the degree of “preparedness” varied widely. Dare I close by commenting that, for some companies, the new regulation may be beyond “reach”?

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Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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SCM's products include: • • • • • • •

North Carolina USA

Manufacturing Sites • Research Triangle Park, North Carolina USA • Suzhou, China Tel: 919-544-8090 • www.SCMmetals.com

Copper, Tin and Bronze Premix Powders Prealloyed Bronze and Brass Powders Copper Base Infiltrating Powders High Green Strength Copper Powders Copper Oxides Copper Base Catalyst Powders Cubond® Furnace Brazing Pastes

Suzhou China

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International: powder injection molding. If you wish to produce complex ceramic and metal products using the PIM process, then come to the leading international specialists in this field: ARBURG. For you, we have the appropriate ALLROUNDER machine technology and the required know-how from our PIM laboratory. With our expertise, you will be able to manufacture efficiently and to the highest quality, prepare material, injection-mold components, debind and sinter - finished! You want to find out more about PIM processing? Simply talk to us!

ARBURG GmbH + Co KG Postfach 11 09 · 72286 Lossburg/Germany Tel.: +49 (0) 74 46 33-0 Fax: +49 (0) 74 46 33 33 65 e-mail: [email protected] ARBURG, Inc. · 125 Rockwell Road · Newington, CT 06111 · Tel.: +1 (860) 667 6500 · Fax: +1 (860) 667 6522 · e-mail: [email protected]

www.arburg.com

gress rld Con PM Wo , 2008 2 June 8-1 30 4 Booth # n D.C. gto Washin

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PM INDUSTRY NEWS IN REVIEW The following items have appeared in PM Newsbytes since the previous issue of the Journal. To read a fuller treatment of any of these items, go to www.apmiinternational.org, login to the “Members Only” section, and click on “Expanded Stories from PM Newsbytes.”

End of PresMet Era Former PM executives Jack Healy and Reynald Sansoucy lament the closing of PresMet Corp., Worcester, Mass., in a recent Worcester Business Journal article. At the time of its purchase by GKN in 2001, the plant had about 350 employees and reported sales of $36 million. Powder Maker Extends Gains Höganäs AB, Sweden, reports an 18 percent sales gain for the third quarter of 2007 to 1,489 MSEK (about $234 million). Sales for the nine-month period ending September 30 hit 4,420 MSEK (about $694 million), a 14 percent increase compared to 2006. Copper Powder Maker Forms JV to Produce Antimicrobial Products SCM Metal Products, Research Triangle Park, N.C., has formed a joint venture company, Cupron Advanced Materials LLC (CAM), with Cupron Inc., Greensboro, N.C., to make raw materials for antimicrobial products used in healthcare, medical, military, and apparel applications. Production of pigmented and non-pigmented pellets made from SCM’s cuprous oxide will begin during the first quarter of 2008. Microwave Furnace Available for Prototype Production Spheric Technologies, Inc., has

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

installed a high-temperature microwave furnace at its headquarters in Phoenix, Arizona. The furnace offers a quick turnaround of process development projects using metal powders and ceramics for prototype parts. Domfer Closing Powder Plant Domfer Metal Powders Inc., LaSalle, Québec, has halted production and is processing its final inventory of salable iron powders with a skeleton crew. Most of the company’s 75 employees have been terminated. Refractories Firm Relocates and Expands Rath Incorporated has relocated to 300 Ruthar Drive, Newark, Del., and will expand operations to a 30,000 sq. ft. space. Owned by Rath AG, Vienna, Austria, the company is combining fabrication, manufacturing, machining, and sales of its insulating refractories into one regional facility. New Material Receives Award Hoeganaes Corporation, Cinnaminson, N.J., received the International Award of Merit from the European Powder Metallurgy Association (EPMA) for AncorMax 200, a new lubricant/binder system for high-density powder metallurgy (PM) parts. The award was presented during the EPMA Euro PM2007 International Congress in Toulouse, France.

MIM Feedstock Producer Sold Purity Zinc Metals, LLC (PZM), Clarksville, Tenn., has purchased Advanced Metalworking Practices, Inc. (AMP), Carmel, Ind. Founded by Kishor M. Kulkarni in 1984, AMP produces feedstocks for metal injection molding (MIM) and provides technical assistance to MIM parts makers. Investor Seeks to Reopen PM Parts Plant Jim Trimmer, treasurer of P/M Tool and Die, Trotwood, Ohio, is seeking funding to purchase the PMG Ohio automotive PM parts plant, according to the Dayton Business Journal. Sources disclose that PMG will close the operation by the end of 2007 and move production to its Columbus, Ind., plant. China Set to Cut Tungsten Exports The Chinese government will trim next year’s tungsten export quota by 900 tons, reports American Metal Market. The new quota is 14,900 tons. QMP Reorganizes QMP Metal Powders, Sorel-Tracy, Québec, Canada, has been integrated into its parent, QIT–Fer et Titane Inc., Rio Tinto, and is now part of the new QIT Steel and Powder Division. QIT supplies molten iron and steel to the metal powder atomizing plant. ijpm

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PM INDUSTRY NEWS IN REVIEW

H.C. Starck Signs Tantalum Supply Contract H.C. Starck GmbH, Goslar, Germany, has signed a 10-year contract to purchase 600,000 pounds of tantalum raw materials annually from Tantalum Egypt JSC, which holds the mining rights for the Abu Dabbab exploration area in Egypt. The contract expands Starck’s raw materials base for the metal as well as supporting its long-term involvement in the tantalum market. New MPIF Lifetime Achievement Award Honors Founding Executive Director The Board of Governors of the Metal Powder Industries Federation (MPIF) has accepted a recommendation by the MPIF Awards Committee to establish a

new award recognizing lifetime achievements in the PM industry. The new Kempton H. Roll PM Lifetime Achievement Award will serve as MPIF's highest-level individual award, expected to be presented every four years to one individual, beginning next year at the PM2008 World Congress in Washington. Austrian PM Company Gains Miba AG, Laakirchen, Austria, reported sales of 286.8 millions euros, a three percent gain, for the first three quarters of its fiscal year. After adjusting for lost revenues resulting from the sale of PM plants in Italy and Spain, the increase was 14 percent. Federal-Mogul Exits Bankruptcy Federal-Mogul Corp. (FMC), Southfield, Mich., emerged from

Chapter 11 bankruptcy on December 27, 2007. The company makes a wide variety of automotive products as well as PM parts and products in plants in the U.S., the UK, France, and India. GKN Updates 2007 Results GKN plc, London, UK, reports profits for the first 11 months of 2007 show a solid improvement over the same period in 2006 with its Driveline, Aerospace, and OffHighway segments all ahead. Its powder metallurgy business dipped marginally below 2006 due to higher raw material costs in the second half of 2007 and some operational disruption stemming from restructuring. ijpm

PURCHASER & PROCESSOR

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1403 Fourth St. • Kalamazoo, MI 49048 • Tel: 269-342-0183 • Fax: 269-342-0185 Robert Lando E-mail: [email protected]

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Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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SPOTLIGHT ON ...

DAVID RECTOR Education: Columbia Basin Community College

What gives you the most satisfaction in your career? New projects. I enjoy the challenge of R&D.

Why did you study powder metallurgy/particulate materials? My great uncle, John Rector, founded Western Sintering Co. (WSC), so I grew up in the PM industry. I have spent a high percentage of my life around presses and furnaces.

List your MPIF/APMI activities. Unfortunately, living in the Pacific Northwest, MPIF/APMI activities are limited.

When did your interest in engineering/ science begin? I was the kid who begged his mother to buy him a 50¢ toaster at the neighbor’s garage sale, so he could take it apart and figure out how it worked. What was your first job in PM? What did you do? I remember tapping PM parts while my father worked on the furnaces during the weekend when I was 5 or 6 years old Describe your career path, companies worked for, and responsibilities. I have worked at WSC most of my life. I started walking to the plant after school when I was 12 years old in order to work in the shipping department. When I turned 18 I came to work full time in the shipping/ receiving department. I boxed parts, worked in the warehouse, and set up pallets for shipment. At age 23 I moved into the press shop, blended powder, and set up tools in both mechanical and hydraulic presses. Most of my time was spent as an operator. I took and passed the PMT I examination at age 24. I also attempted the PMT II examination two years later, but did not pass. I have not retaken the test as it has not been offered since. After about five years I moved into the sintering department and have been managing the operation for over a year now. I am in charge of new procedures, sintering R&D, basic maintenance, and scheduling.

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

What major changes/trend(s) in the PM industry have you seen? The biggest change I have seen is globalization. The percentage of “American made” products that contain parts manufactured overseas has increased dramatically since I became familiar with the PM industry. Why did you choose to pursue PMT certification? I did not finish college. PMT certification allowed me to prove that I was competent and knowledgeable in my chosen field. How have you benefited from PMT certification in your career? I learned about several processes of which I previously lacked knowledge, despite growing up with iron powder behind my ears. PMT certification allowed me to prove my abilities in the field. What are your current interests, hobbies, and activities outside of work? I spend my summers wakeboarding and wakesurfing on the Columbia River. In winter you will find me on a mountain snowboarding. In my free time I read voraciously, play chess, shoot pool, and occasionally substitute as a goalkeeper on a local recreational league soccer team. Manager, Sintering Operations Western Sintering Co Inc 2620 Stevens Drive Richland, Washington 99354-1752 Phone: (509) 375-3096 Fax: (509) 375-3594 Email: [email protected]

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CONSULTANTS’ CORNER

JAMES G. MARSDEN, FAPMI* Q

When steam is injected into the sintering furnace, there is concern about parts corroding and being subjected to high-temperature reactions. What is the role of steam and the injection of water vapor during the sintering of powder metallurgy (PM) parts? As previously explained (IJPM, 2007, vol. 43, no. 1, pp. 15–16), it is crucial that the oxidant (steam) does not enter the high-temperature zone of the sintering furnace. If this occurs, it will definitely result in high-temperature oxidation of the sintered compact. This is precisely why the injector for the steam should be located approximately two-thirds to three-quarters of the distance from the point of entry to the end of the preheat zone, and be directed at about 15° toward the point of entry. The recommended maximum dew point of the moisturized atmosphere is between 1.7°C and 7.2°C (35°F and 45°F). Although a higher moisture content may not oxidize the compacts at the delubricating temperatures, the excessive moisture on the compacts could be carried into the high heat zone and cause high-temperature oxidation, resulting in the formation of Fe3O4 (black/flaky oxide). This condition could result in internal oxidation of the sintered compact. When introducing moisture into the preheat zone of the furnace, the following procedure should be followed: place a 6.35 mm (0.25 in.) dia. stainless steel probe down the middle of the belt into the high-heat zone. Using a pump and dew point analyzer, take a dew point reading in this area, using the pump to make sure that a representative sample is obtained. If sintering in a nitrogen–hydrogen or nitrogen–dissociated ammonia atmosphere, expect dew point readings between -40°C and 51°C (-40°F and -60°F). With a nitrogen–endothermic atmosphere, dew points should be between -20.5°C and -10°C (-5°F and -15°F). Next, move the probe into the area where the moisture is injected

A

and set the moisture level to produce the recommended dew point. Once the system is set up and operating in the selected dew point range, push the probe back into the high-heat section and take another dew point reading. If the dew point in the high-heat section is the same as the first reading, backward flow of moisturized atmosphere into the high-heat section is not occurring and there should be no problem with hightemperature oxidation. The role of steam or water vapor injected into the preheat section of the sintering furnace is to add an oxidant to combine with the carbonaceous vapors produced during delubrication of the PM compact. With this method, the unit is placed as close to the injection point of the furnace as possible to assure that there is no condensation of moisture in the supply line from the unit to the furnace. In addition, it is a system in which the water can be adjusted to compensate for compacts containing excessive lubricant additions, or with larger compacts that require more lubricant. The moisture (H 2O) will combine with the carbonaceous vapors given of f during the lubricant removal process to form gaseous products (CO, CO2, and some hydrocarbons). Once these vapors are in the gaseous state they can be removed from the furnace with the furnace atmosphere, thus eliminating the build-up of high-carbon stalactites and stalagmites on the furnace components.

Q

What is the optimum presinter temperature profile for delubricating PM parts? Does the optimum profile vary for binder-treated materials, compared with materials in the absence of a binder?

*Consultant, Furnace & Atmosphere Service Technology, Inc. (F.A.S.T., Inc.), P.O. Box 43, Big Run, Pennsylvania 15715-0043, USA; Phone: 814-427-2228; E-mail: [email protected]

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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CONSULTANTS’ CORNER

A

I assume that the reference is to a bindertreated material in which the binder is added to assure a homogeneous distribution of the alloying elements with the base powder. Although the lubricants are normally organics and the binders are polymers, they are both removed in the first stage of the sintering process. Most lubricants melt between 45°C and 150°C (112°F and 302°F) but do not evaporate until the compact reaches temperatures ~300°C to 500°C (572°F to 932°F). The lubricant should be totally removed by 550°C (1,022°F). The binders start to decompose at about 150°C (302°F) and peak at ~450°C (842°F) and, similar to the lubricant, the removal of the binder is usually complete at 550°C (1,022°F).1 Since both the lubricants and the binders contain relatively high percentages of carbon, they both produce soot if there is no oxidant added to the furnace to combine with these vapors. In the past, I have set up numerous furnaces with nitrogen–hydrogen and nitrogen-diluted atmospheres. To my knowledge, the preheat temperature profiles are not changed when sintering compacts made from powder premixes containing binders, or with

compacts made from powder premixes without a binder addition. With respect to the optimum preheat profile, this depends on several conditions. How many zones are in the preheat section? What size compacts are being sintered? What is the mass and green density of the compacts to be sintered? What is the belt speed in relation to the size of the total preheat section? In my opinion, the most realistic way to determine the optimum profile in a sintering operation is to place a thermocouple in the middle of a compact, fully load the furnace with compacts, and determine when the center of the compact reaches temperatures slightly higher than those required to remove the lubricant and binder from the compact during sintering. What are the state-of-the-art advantages and disadvantages of systems for on-site generation of N2/H2 sintering atmospheres? I am most familiar with two small nitrogen systems, namely, the molecular sieve pressure swing absorption (PSA) and the cryogenic reduction (LIN-ASSIST) systems. Both systems require a

Q A

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FURNACES INC. 103 Dewey Street Bloomfield, NJ 07003-4237 Tel: 973-338-6500 Fax: 973-338-1625 Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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CONSULTANTS’ CORNER

minimum usage of 171 ML (6 M ft.3) per month of nitrogen to be economical. The units are usually installed and maintained under a long term contract (usually 15 years) with the industrial-gas supplier. Thus, it is prudent to be cognizant of long-term projected growth, and the ability of the unit to supply projected needs in the future. The PSA unit has a purity of approximately 99.9 v/o. The unit may require that it be housed in an enclosure which would require a dedicated building or floor space in the manufacturing facility. The unit is comprised of two large separation vessels that reduce the air, under pressure, by utilizing a carbon molecular sieve material. In the process, air is filtered, compressed, and further treated to remove unwanted components (air and water). The compressed air then enters a vessel which contains the carbon molecular sieve material which absorbs the oxygen and CO2 and allows a nitrogen-rich stream to pass through the vessel and be delivered to the customer by pipeline. One vessel takes in air while the other vessel is depressurizing. This switching action results in a noisy system, a minor limitation unless it is located in a

W NE

!

residential area. Any further improvement in purity requires the use of hydrogen in a deoxidation stage with subsequent drying to produce oxygen levels in the range 2 to 5 ppm. The liquid nitrogen–assist generator uses liquid nitrogen supplied from an on-site vessel to provide refrigeration “assist” in the cryogenic separation process that separates nitrogen from the atmosphere. Previous cryogenic separation technology for nitrogen utilized a turbine expander to provide this refrigeration. As with the PSA, air is filtered, compressed, and further treated to remove unwanted components (oil and water). The compressed air is cooled and then enters the cryogenic air separation column where it is distilled into its components, including nitrogen (99.999 v/o purity) which is removed from the cold box and delivered to the customer by pipeline. The unit produces oxygen levels in the range 2 to 5 ppm without additional accessories. It is usually located outside of the facility, and does not need a special enclosure. There are other smaller, lower-volume nitrogengeneration units for rent and/or sale, such as the

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For info please visit w w w.bucorp.com or call 1-800-METAL20

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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CONSULTANTS’ CORNER

membrane system. These systems, however, are usually low in purity and are usually not suitable for sintering PM compacts. I would not recommend a unit for nitrogen or hydrogen that produces oxygen levels >10 ppm. Even in the sintering of copper alloys, where slightly higher oxygen levels can be tolerated, I would still be cautious of the purity. There are two methods used to produce hydrogen for the volumes typically used in a PM facility. One utilizes natural gas as the feed gas in a steam methane reformer (SMR). The other is electrolytic separation of water. Generally, the gas production ranges of these technologies are 5,714–285,700 L/h (200–10,000+ ft. 3 /h) for electrolysis and 57,140–285,700 L/h (2,000–10,000+ ft. 3/h) for smaller SMR units. Both technologies can offer 99.999 v/o purity levels with oxygen and water in the single-digit ppm range. Economically, in the overlapping capacity ranges, the SMR technology affords a lower effective unit cost. I greatly appreciate input to the answers for these questions by Mr. Michael Stempo, Air Liquide, and Mr. Paul Bassa, Air Products and Chemicals, Inc. ijpm 1. R.M. German, Powder Metallurgy of Iron and Steel, 1998, John Wiley & Sons, Inc., New York, NY.

Readers are invited to send in questions for future issues. Submit your questions to: Consultants’ Corner, APMI International, 105 College Road East, Princeton, NJ 085406692; Fax (609) 987-8523; E-mail: [email protected]

ijpm

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THIS JUNE THE PM WORLD CONVENES IN WASHINGTON, D.C. 2008 World Congress on Powder Metallurgy & Particulate Materials June 8–12, Washington, D.C. • International Technical Program • Worldwide Trade Exhibition • Special Events This global PM event is sponsored by:

METAL POWDER INDUSTRIES FEDERATION APMI INTERNATIONAL 105 College Road East Princeton, New Jersey 08540 USA Tel: 609-452-7700 • Fax: 609-987-8523 www.mpif.org In cooperation with:

Held in conjunction with the:

GAYLORD NATIONAL RESORT AND CONVENTION CENTER On the Potomac at National Harbor, Maryland

8 Tungsten, g Refractoryy & Hardmaterials VII

2008 International Conference on Tungsten, Refractory & Hardmaterials VII

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GLOBAL REVIEW

POWDER METALLURGY IN ITALY Oreste Morandi* and Enrico Mosca**

This review of the status of powder metallurgy (PM) in Italy covers all aspects that relate to the use of powders. It highlights activities that make the country unique in its involvement in the technology. Today the PM industry in Italy is healthy, and current conditions bode well for future developments.

INTRODUCTION In relation to structural parts, PM in Italy has a long and successful history. Examples include innovation in the design of components (Olivetti, split-die principle, and the development of presses to handle special tool sets); improvement of processes to fabricate unusual shapes with attractive properties; and the ability to cater to markets outside the automotive sector. The novelty of the solutions included in some of Italy’s PM products has resulted in international recognition. Over the years Italian PM companies have won three Grand Prizes and nine Awards of Distinction in the International Design Competition sponsored by the Metal Powder Industries Federation (MPIF). Today, the evolution of the Italian PM industry is oriented primarily towards a strengthening of its traditional products, since there remains room for growth of these markets, especially in relation to structural components for mechanical applications. It is here that PM is frequently gaining success at the expense of other metal-shaping processes. There are attendant problems since PM technology is relatively mature, and some components that in the past made a substantial contribution to the domestic output are now manufactured at production sites located in countries with low-cost manpower. For example, this is the case for PM refrigerator compressors parts, whose production in Italy has experienced a precipitous decline, dating back to the 1990s. In this Global Review, the primary characteristics, history, and evolution of the Italian PM industry are described. The review illustrates the development of the technology and related activities, including a perspective on the future. PRODUCTION OF STRUCTURAL PARTS AND SELF-LUBRICATING BEARINGS On the European scene, Italy places third at 13.5%, behind Germany and Spain, in terms of production volume. Figure 1 gives the output in 2005, by country, while Figure 2 shows a chronology of PM in Italy over the last 30 years in terms of the production of structural components and self-lubricating bearings. The figures includes copper and stainless steel parts. From 1975 to 2000 the annual growth was 6.8%, but since 2000 there has been no major growth.

*Assinter Secretary, Casella Postale 272, 10015 Ivrea (TO) Italy; E-mail: [email protected], **Consultant, Corso Monte Cucco 131, Torino 10141, Italy; E-mail: [email protected]

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Figure 1. Production of PM components in Europe in 2005 (Source: European Powder Metallurgy Association)

The sector embracing general mechanical applications includes instrumentation, hardware, mechanical devices, agricultural equipment, motorcycles, and scooters. This sector is of major importance, accounting for at least 20%–25% of the total. In total, the three non-automotive sectors account for at least 45% of the tonnage of parts produced. This means that the automotive output is only ~55%, compared with ~70%–80% in all the other industrialized countries. The difference can be attributed in part to the smaller number of PM parts in Italian cars (usually <7 kg), compared with an average of 9 kg in Europe. Exports represent >50% of the output (Table I), confirming that Italy is a preferred global supplier of quality PM parts. One of the leading Italian PM parts companies has opened new plants abroad and this tempers the level of exports! Table I includes other significant data on the Italian PM industry. Note the increase in the productivity index over the decade 1991–2000. This

Figure 2. Production of PM structural components and self lubricating bearings in Italy

Figure 3 shows the growth of the PM markets in Italy, Europe, and the World, taking 1993 as the starting point with an index of 100. The growth of the PM industry in Italy is comparable with that in Europe, but now there is a slowdown. This is due primarily to the loss of low-end components for which production has moved to companies located in developing countries. Figure 4 shows how PM production in Italy since 1998 has been subdivided among the four main application sectors. There is a marked decline in the demand for domestic appliances; in 1991 this sector accounted for 12% of the total, while now it is ~7.6% and the trend is negative. The power tools/“do-it-yourself” sector reached maturity in the 1990s, and today remains strong. Applications are also found in professional power tools, due to superior mechanical properties and to improvements in the construction and precision of the die sets.

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Figure 3. Market growth in Italy, Europe, and worldwide since 1993

Figure 4. Production of PM components in Italy, subdivided in the four primary applications sectors

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TABLE I. PROFILE OF THE PM INDUSTRY IN ITALY Number of Companies Number of Plants Number of Employees Production (mt) Sales (M ) Exports (M ) Productivity Index mt per Plant

1991

1995

2000

2001

2002

2003

2004

2005

2006

19 22 1,250 13,000 69.7 28.9 5 10.4 591

17 21 1,230 19,000 124.0 54.2 15.4 905

18 22 1,550 26,630 192.6 95.1 17.1 1,210

19 23 1,550 26,350 188.5 96.1 17.0 1,145

20 24 1,495 26,500 195 104.9 17.7 1,104

21 25 1,490 26,670 198.8 109.5 17.9 1,067

22 25 1,508 28,270 210.7 118.2 18.7 1,130

22 25 1,492 26,311 204.1 117.6 17.6 1,052

22 25 1,519 28,952 223.6 130.8 19.0 1,158

is attributed to the combined effects of a positive trend in the market, the introduction of technical improvements in operations, and investment in machinery and automation. The average size of Italian PM plants is significantly smaller than those in the rest of Europe; moreover, their size has not undergone substantial changes as a result of acquisitions or mergers. Such events occurred less frequently in Italy than in the rest of Europe between the mid-1980s and the mid-‘90s. The large number of PM fabricating plants in Italy (22) compares with a relatively small number in the other European countries. Over the last decade, a number of new small companies came into existence. By examining the market for sintered components and the evolution of PM companies in Italy, it is possible to draw the following conclusions: • Taking into account the automotive sector, Italian PM companies were not affected significantly by the “ups and downs” of the car industry and, much more important, most of the companies succeeded in breaking into new, non-automotive markets. • Most of the Italian fabricators of PM components and bearings are well known and respected abroad, as reflected in the export figures. This means that the PM industry in Italy is healthy and, for the years to come, prospects are encouraging. • Excluding metal injection molding (MIM), from an industrial perspective, pressing in rigid dies remains the only technique used for fabricating structural components. Other shaping methods—for example, powder forging (PF), or hot isostatic pressing (HIP)—have not progressed beyond the laboratory stage. METAL INJECTION MOLDING ACTIVITIES During the mid-‘90s some companies lacking Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

previous experience in the traditional PM field began to explore the pilot-scale production of MIM parts. Today five companies are active on a relatively small scale, as compared with what happens abroad. Now production is growing at an accelerated rate, Figure 5. Typical components are orthodontic brackets and dental parts, and complex structural components. These compete with parts fabricated by investment casting. POWDER PRODUCTION Only one Italian company is active in this field. Production and export figures since 1998 are given in Table II. Powders include atomized iron and copper, bronze, electrolytic copper, and tin. Significant quantities of steel shot are manufactured, together with brass, magnesium, and zincbase powders. HARDMETALS AND FERRITES For structural parts, information is available on a company-by-company basis since all the Italian PM companies send their data to ASSINTER annually, covering production, turnover, and the subdivision among the four major sectors. In con-

Figure 5. Sales of MIM parts in Italy

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TABLE II. POWDER PRODUCTION IN ITALY 1998

1999

2000

2001

2002

2003

2004

2005

2006

PRODUCTION (mt) Iron-Base Powders Copper-Base Powders

4,464 2,932

4,834 3,262

5,919 4,044

6,200 4,150

6,300 4,375

7,050 4,730

9,150 4,350

8,750 4,350

10,500 4,600

EXPORTS (%) Iron-Base Powders Copper-Base Powders

20 20

16 25

14 27

22 30

17 37

20 36

35 32

30 32

25 35

trast, for hardmetals, data about this industry can only be derived from estimates. In this field 14 companies are active, with a turnover of about 160 M and exports of 45 M . All the powders used in cemented carbides are imported. Since the value of imports of hardmetal products is about 90 M , the balance of payments is negative. With respect to ceramic magnetic materials, only hard ferrite powders are produced in Italy. Only one company is active, but its output is significant, namely, 15,000 mt/yr, most of which is exported within Europe. This company also produces 8,000 mt/yr of bound ferrites for refrigerator gaskets. DIAMOND TOOLS Marble and ornamental-stone quarries are found everywhere in Italy. In consequence, industrial activity has allowed the country to gain a large share of the market for these materials. Since stones need to be cut, drilled, and polished, a flourishing industry has developed around the diamond tools required for these operations. More than 170 small companies are active in this field. Unfortunately, data covering output and turnover are not available. PM EQUIPMENT Hydraulic compacting and sizing presses for PM are available from two Italian suppliers. Capacities are in the range 50–800 mt and the presses are equipped with computerized stroke control, force, and position. One company offers control of up to nine independent motions. Both companies have established themselves in the international market and supply presses with performance and quality standards comparable with their European competitors. At least six companies manufacture sintering furnaces, including vacuum furnaces, offering comprehensive solutions for control of the sinter-

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ing process. Steam-treating and heat-treating furnaces are also offered. For PM tooling and dies, several companies have the requisite knowledge and are equipped to supply tooling as well as automation to the PM industry. Of these companies, at least five are highly specialized in this field and innovative, being on the forefront of technological tooling and die developments. PM ASSOCIATIONS In Italy there are two organizations involved in the promotion of knowledge and applications of PM. The first association is the Centro Metallurgia delle Polveri (CMP), a section of the Associazione Italiana di Metallurgia (AIM), founded in 1949. At that time, PM industrial activity in Italy was developing to a degree that there was a need to gather and disseminate technical and scientific experience on the young technology. Since its inception, CMP has organized a systematic activity to spread PM knowledge and to promote the application of structural PM parts. This has been accomplished by organizing meetings, seminars, and refresher courses, usually oriented towards technical people (in particular the designers of PM parts) in end-user companies. Up to now, 10 of these courses have been held, some of them in cooperation with Assinter. It is of interest to note that several seminars involving PM part suppliers and end users have been organized at major Italian PM factories. Following the lectures, all participants were allowed to visit the plants. In 1982, in cooperation with the European PM Federation (at that time EPMA did not exist), AIM organized the International PM Conference in Florence. In 1983 a book specifically addressing the designers of PM parts 1 was published in Italian and afterwards in English. Today CMP operates in cooperation with EPMA Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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and some of its members are active in EPMA groups. For example, members cooperate as tutors in events such as short courses (three courses were organized in Italy) and summer schools throughout Europe. To further promote PM applications, and following the example of MPIF, EPMA, and the Japan Powder Metallurgy Association (JPMA), in 2005 CMP decided to give awards of excellence for the best innovative parts fabricated in Italy. The first competition was held in 2006. Examples of award winning PM parts are illustrated in Figures 6, 7, and 8 , for the 2007 competition. The second organization is Assinter, a trade association founded in 1983, initially with the aim of gathering the suppliers of PM parts, and more recently embracing all the companies involved in PM. This includes hardmetals, powders, equipment, tooling, universities, and research centers, in order to promote awareness of PM and to offer to end users qualified and reliable products and services. Every year Assinter publishes a press release, outlining PM news and new developments. Besides its normal functions, the main activity (sometimes in cooperation with CMP) has been the organization of user-oriented seminars (in six different locations and one at Fiat), culminating in the preparation and complimentary distribution of technical publications (Guides) especially to designers in end-user companies in Italian and in English.2 These booklets have been distributed, not only in Italy but also abroad, to end users of PM products, university and polytechnic school students, and secondary school (high school) students. Direct promotion of PM capabilities has been accomplished extensively in Europe and recently EPMA has borrowed from our example. For instance, the new generation of students were approached by organizing half-day seminars in different locations in Italy. Currently 20 seminars have been given to engineering students in our polytechnic schools, and 58 seminars to high school students. Besides the Guides, teachers receive teaching aids, together with examples of typical PM components. All this material can be used in their lectures covering PM technology. PM TEACHING AND RESEARCH In Italy it is not possible to obtain a degree in PM. However, due to the promotional efforts carVolume 44, Issue 1, 2008 International Journal of Powder Metallurgy

Figure 6. Gear assembly utilized in a servo control—first place award. Carbosint

Figure 7. Sintered components utilized in a gas compressor—second place award of merit. Stame

Figure 8. Ratchet gear with helical grooves utilized in a brake system for trucks— second place award of merit. mG miniGears

ried out by CMP and Assinter, many universities are now offering detailed lectures on the basic technological aspects of PM as a part of their courses in materials engineering. During their graduation theses (in Italy or

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abroad, for example, in the framework of EC programs) students are encouraged to work on research projects directly related to industrial problems, sometimes with the help of an industrial tutor. Students and young graduate engineers are also encouraged to attend refresher courses organized by the Italian PM associations, and the EPMA summer schools and short courses. Besides the personal interest of teachers, PM teaching in high schools is dependent on the material distributed during the seminars, or which is mailed directly to the teachers. Major Italian PM companies have their own research groups focusing on local problems. Usually most of the developments requiring basic knowledge are pursued in academic institutions where, in some cases, they have the necessary pilot equipment. Seven universities and polytechnic schools, by themselves or in cooperation, have PM research activities financed internally and sometimes by PM companies. In some cases, research, included in national or European projects, is performed in cooperation with research institutions abroad. Examples of recent research topics include: • Optimization of the design of compacting dies and evaluation of their reliability with FEM methods (Naples) • High-temperature properties of aluminum and magnesium alloys; nanomaterials obtained by spark plasma sintering (Ancona) • Response to sinterhardening as a function of composition and characteristics of the components; corrosion behavior of stainless steel; and steam-treated parts (Genoa) • Hardenability of PM parts; use of universal hardness testing on PM materials; fractal analysis applied to PM (Milan) • Application of PM to the goldsmith’s art; PM superalloys (Padua) • Influence of infiltration processes on properties; reactive sintering of PM stainless steels; induction hardening of sintered parts; new hardmetal compositions; new materials for diamond tools; and use of coated diamonds (Turin) • Sintering and heat treatment of low alloy high strength materials; use of boron as a sintering aid; wear behavior of porous materials; powder materials alternative to cobalt for the production of hardmetals; high temperature vacuum sintering processes; evaluation of

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When it comes to grinding or flaking metal powders, properties of fine grain, nanostructured and functionally graded materials (Trento) On occasion research topics are also pursued at the universities of Rome and Udine. In 2002, a student at the Politecnico di Torino won the EPMA Masters Category Thesis Competition with the topic, “High-Density Sintering of Duplex Stainless Steels.” FUTURE PROSPECTS Competition becomes harder and globalization pushes countries with low-cost manpower to enter the European market. But Italy has trump cards, namely, the capability to operate in the high-end segment of the market, less dependence on fluctuations in the automotive sector, excellent support from research institutions, and leadership in the promotion of PM applications via the education of present and potential end users. Drawbacks are related to the small size of most of the Italian PM companies and the low frequency of mergers. These tend to limit investments in new or updated equipment necessary to pursue the growing demands of customers, and reduce the capability to innovate in the event of rapidly developing opportunities in new markets. Having examined the situation, the short-term scene seems to exclude abrupt changes in the business and the national trend will follow the general evolution of the market. In the long term, it will be necessary to develop an increasing number of new applications in all fields, otherwise a healthy survival of the PM industry in Italy is not guaranteed. REFERENCES 1. E. Mosca, Powder Metallurgy: Criteria for Design and Inspection, AMMA, Torino, 1984. 2. Assinter Publications (in English) • “Guide to the Usage of Sintered Parts”, 1989 • “Post-Sintered Components: Production Cycle”, 1991 • “Competitiveness of Sintered Components: Guide to Technological Alternatives”, 1996 • “Guide to the Design of Sintered Parts”, 1996 • “Guide to the Quality Assurance of Sintered Parts”, 2000 3. G.F. Bocchini and A. Molinari, “PM in Italy: Present Status and Prospects”, Int. J. Powder Metall., 1996, vol. 32, no. 4, pp. 307–313. ijpm

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RESEARCH & DEVELOPMENT

EFFECT OF DIE FILLING ON POWDER COMPACTION Dzmitry Korachkin*, David T. Gethin**, Roland W. Lewis** and James H. Tweed***

INTRODUCTION Controlling the density of pressed parts is a crucial step in the manufacture of sintered powder products. It is well established that any inhomogeneity introduced at this stage will be reflected in differential shrinkage during sintering or a variation in mechanical properties, depending on the powder type. Die filling may appear simple but, in reality, it is a process with a multitude of complications. Previously, attention has been focused on the completeness of die fill. This includes work on developing measurement methods to quantify powder flow together with exploring the attendant impact on die-fill density. The Hall flowmeter1 is normally used to measure the flow rate of metal powders and mixtures, but other methods have been suggested. One such approach, introduced recently, is the variable-aperture flowmeter. This device comprises a cup with an iris at its base, allowing for a large range of openings, thereby permitting characterization of powders having good and poor flow properties in one device.2 Other methods for quantifying the flow of powders with poor flow characteristics have also been developed; such powders are commonly used by the chemical, food, and pharmaceutical sectors.3 This work also identified the consequent importance of powder flow, including the rate of die fill, its uniformity, and its reproducibility. A number of investigations into the effect of process parameters on die filling, together with the consequent effect on fill density, have been reported in the literature. For example, the effect of die-fill parameters on density variations in ring-shaped compacts has been reported.4 The study examined four sections of a ring-shaped die and compared their densities after filling under a range of fill parameters, including settling time, feedshoe speed, number of feedshoe passages and shoe-powder level. Also discussed were the mechanisms influencing the die-fill density. Gravity, air resistance, shoe speed, and the shear forces from the powder in the shoe were cited as being most influential. In other recent work, a novel die-filling test rig was considered which consisted of a transparent die and a filling shoe.5,6 The transparent design allowed for high-speed video recording of the die-filling process. Both the quantitative and qualitative assessments of the

The paper describes a numerical simulation study undertaken to explore the effect of variations in fill density on the final-density distribution achieved within a pressed part and the associated effect on tool stresses. Three powders were used in the sensitivity study (ferrous, hardmetal, and ceramic) and the pressing kinematics employed reflected the compressibility of the powder systems. Two generic geometries were considered, a plain cylinder and two multilevel parts. Through exploration of density and stress evolution during compression, it was found that variations in die-fill density had the most significant effect on tool stress levels, leading to increases up to 64% when compared with the stress levels achieved with a uniform die-fill density. Pressed-density variations were also subject to significant changes when compared with uniform fill-density conditions, achieving variations up to 35%. The changes in density and stress level were dependent on the powder type and the initial die-fill distribution assigned at the initiation of compression.

*Research Student, **Professor of Engineering, School of Engineering, UW Swansea, Singleton Park, Swansea SA2 8PP UK; E-mail: [email protected], ***Principal Consultant, AEA Technology, Harwell, Didcot Oxfordshire OX11 0QJ, UK

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effect of powder characteristics and shoe motion on powder flow into a cavity were undertaken. These authors then measured filling rate and the ratio of powder volume to available die-cavity volume for different configurations of die and shoe. The effect of air on die filling was explored through additional tests in vacuum with both positive and negative contributions being reported. The concept of a critical shoe velocity as a method of characterizing the flowability of powders was introduced later.6 It is defined as the maximum shoe velocity at which the die is filled completely and can be used for both powder characterization and to assist in process design. Work has been undertaken to explore the impact of filling on the initial density distributions within the die. While some authors were able to determine bulk density in vertical sections of the compact, detailed measurements proved to be more difficult. The sintering of loose powder after die fill allows for the density within smaller sections to be determined by conventional methods. However, handling of the die and sintering can affect the density distribution. A convenient way of determining the fill-density distribution is through the use of X-ray computerized tomography (CT).7,8 Detailed information on the density distribution throughout the compact, including that at the start of compaction, can be obtained using this technique. Although it is acknowledged that powder-flow behavior, combined with filling-system design and process operation, can have a significant effect on the fill density within the die, the consequent effect on the final-density variation in the pressed powder is unknown. Only limited work has been done to explore its impact. 9,10 The authors restricted their exploration to a single part shape, combined with a limited number of initial density variations derived from visualization experiments, and fill simulation using a discrete particle technique. The present study extends this work9,10 through a more-systematic exploration of part shape; it uses fill density determined through CT scans on simple and complex die shapes. CASE STUDIES Previous work11 compared experimental work with the prediction of compact density. One finding from this comparison was that agreement could be enhanced through an improved definition of the fill density. Consequently, the following Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

case studies have been devised to explore the impact of filling on the final pressed density in a number of part geometries and powder types. Although the geometries are generically similar, the actual dimensions reflect parts that are made using the respective powder types. Powders representative of three different types were included in the case study: • Hardmetal—tungsten carbide–cobalt; composition: 10 w/o Co-2 w/o binder PolyEthylene Glycol (PEG)-balance WC; spherical granules 200–500 µm. • Ferrous—Distaloy AE; composition: 0.5 w/o graphite (C-UF4)-0.6 w/o Kenolube-balance iron; irregular particles 25–75 µm. • Ceramic—zirconia; granule size 30–80 µm These powders were chosen since they differ in particle size, shape, roughness, strength, and ductility. The granules are approximately spherical, but differ in size and strength, whereas the Distaloy AE is irregular and hence is likely to promote interlocking and bridging which, together with the ductility of the material, will result in particle deformation at lower loads than those used to compress hardmetal. This phenomenon is most likely to occur at interparticle contact points and will result in a reduction of the time for which rearrangement of the particles takes place. The bridges vary in strength and collapse at increasing force levels, resulting in a phase where both particle deformation and rearrangement (during the collapse of the bridges) occur at the same time. The differences in particle morphology and material properties in the three powders result in different extents for which these two compaction modes are present. This may result in a differing sensitivity to fill density variations. Whether this is indeed the case is explored in the present study. A continuum scale model was used to simulate the compaction process; such models are now becoming well established for powder pressing.11 The system used in this study was a Cam Clay material model, chosen because it is relatively easy to characterize experimentally. The equations used to define this model are set out in Appendix A. Friction contact between the powder, die, and punch surfaces was also accounted for. The material models used in the simulation were validated through comparison of punch forces derived from the simple uniaxial die-pressing test that was used to determine the material parameters. Material model parameters were optimized such that the

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top punch stress levels from experiment and simulation agreed within 20 MPa for ferrous and zirconia powders, and within 5 MPa for tungsten carbide. The simulation assumed a uniform die-fill density; given that the dies used for material characterization were simple cylinders (typically 10 mm dia. × 20 mm high) this is reasonable. The final requirement relates to part geometry and tool set kinematics. Details are summarized for the respective case studies. Die-Fill-Density Distribution Fill-density distribution can be affected by a number of parameters, including flowability of the powder, shape and orientation of the die and filling shoe (wide or narrow die, steps in the die), method of filling (gravity or vacuum-assisted fill, height of powder in the hopper), use of shakes, and number of passes of the fill shoe. 12 This study attempts to assess the effect of die-fill-density distribution, affected by the cited process parameters, on the pressed density of the compact. To this end, a comparison was made between simulated compacts in which the die-fill density was uniform, and in which it was not. The study was initiated with a simple geometry. If simple compacts are affected significantly by the die-fill-density distribution, then it is expected that this will also have an effect on more complex geometries. A hollow cylindrical geometry was considered as the first shape in the study. Hollow cylindrical components are a common powder metallurgy (PM) product. The presence of a core rod restricts powder movement both via its physical presence, and through friction between the rod and the powder. The inner and outer diameters of the hollowcylinder geometry selected are given in Table I. Wu and Cocks 10 have confir med that for geometries with a high aspect ratio there was a risk of air entrapment and bridging of the powder. This most likely occurs for powders with irregular shapes and high surface roughness as such particles are most likely to interlock, promoting the formation of bridges. This geometry may also be difficult to fill completely in a given time for lowerdensity materials, as light particles are prevented from entering the die by the flow of air escaping from the die. However, in this study the focus was on the variation of the die-fill density, rather than on whether or not the die could be filled completely. To this end, Distaloy AE powder was selected

24

for this geometry. Another common subset of geometries consists of flanged components with either an external or an internal flange. Thus two components, one with an external flange13 and a second having an internal flange,11 were considered. Because these part geometries were explored extensively in two European network projects, the first is referred to via the project acronym as “Dienet” and the second as “Modnet.” The Dienet geometry, with dimensions, is shown in Table II. The Modnet geometry is shown in Table III. For the case-study results presented in this work, the line designated “NP” (see Tables I–III) represents a neutral plane and the kinematics are defined so that no powder flow occurs across it. Both flanged geometries consisted of a wide top part and a narrow lower part. Burch14 has shown, via X-ray CT, that the die-fill density is likely to be lower in the narrow lower section of these twolevel components, Figure 1; the difference is typically 10%. Double-ended compaction kinematics were used for each geometry and the punch displacements were selected to provide the required compaction ratio. NP was at the center of the cylindrical compact and was located on the section change in both the Dienet and Modnet geometry parts. Figure 2 depicts schematically the kinematics used to achieve an NP at the levels designated. Also the punch travel was set such that the compaction ratio on each side of the NP remained the same. This minimizes the effect of flow between the upper and lower sections within the compact, allowing fill effects to be explored independently and systematically. Practically, kinematics may be chosen such that there will be significant flow in this region, but this also depends on the powder type that is being compacted. Sensitivity Study—Cylindrical Compact Geometry The simulation system used in this study is an in-house code that runs on a PC platform. This code has been validated for parts produced using press kinematics. Generally it is found that, for a ferrous powder, the density variation can be predicted to within 2%, and the tool forces to within 10%.11 The sensitivity study began with the cylindrical Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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TABLE I. HOLLOW-CYLINDER GEOMETRY Nominal Compact Geometry H (mm) Inner Dia. (mm) Outer Dia. (mm) Fill Height (mm) Assumed Fill Density (g/cm3) Compaction Ratio

30 25.8 47.8 60 3.3 2

TABLE II. DIENET COMPACT GEOMETRY Nominal Compact Geometry H1 (mm) H2 (mm) Target Press Density (g/cm3) Fill Density (g/cm3) Compaction Ratio Part Internal Radius (mm)

11.36 22.72 7.1 3.09 2.2 1.0

Fill Geometry H1 (mm) H2 (mm)

25 50

TABLE III. MODNET COMPACT GEOMETRY Nominal Compact Geometry H1 (mm) H2 (mm) Inner Dia. (mm) Mid-Dia. (mm) Outer Dia. (mm) Assumed Fill Density (g/cm?) Compaction Ratio

16 13 29 68 78 3.3 2

NP = neutral plane

Figure 1. X-ray CT of a filled die

geometry. Fill density was taken to be 3.3 g/cm3 in the case of uniform die fill with a compaction ratio of 2.0. For the case of nonuniform die fill, the compact was divided into two regions of equal density, namely the top and bottom halves. The density in the top part was set 10% higher than Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

that in the lower part. Mass balance was maintained to keep the average fill density at 3.3 g/cm3, Figure 3. The compaction was then simulated for both the uniform and nonuniform die-fill distributions. In each case identical double-ended compaction kinematics (Figure 2) were employed.

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Figure 2. Compaction kinematics: (a) cylindrical compact geometry, (b) Dienet compact geometry, (c) Modnet compact geometry

of simple shape, at the end of the compaction process, variations in the die-fill-density distribution along the axis of the compact play an insignificant role. This is a result of the powder in the region of lower density being initially compressed until it reaches a similar density to that in the other parts of the compact. Thereafter, compaction proceeds normally, resulting in essentially an identical final-density distribution.

Figure 3. (a) uniform fill density, (b) two regions with balanced masses

Sensitivity Study—Dienet Compact Geometry Having established that, for simple compact geometries, the die-fill-density distribution had no significant influence on the compact density, the next step in the study was to consider a more complex part shape for the ferrous, hardmetal, and ceramic powder systems. Ferrous Powder After exploring the factors affecting the die-filldensity distribution, and having analyzed the Xray CT scans available for dies filled using ferrous powder, four initial density configurations were selected, as shown in Figure 5. First, a compact with a uniform fill density of 3.09 g/cm 3 was modeled as the benchmark simulation. The remaining configurations each consisted of two regions of different density at fill: a region of higher density in the upper section and a region of lower density in the lower section, so that the

Figure 4. Compaction of ring compact (a) nonuniform, and (b) uniform fill density. Compaction stages in 10% increments starting at 10%

The resulting density distribution during the compaction process is plotted in Figure 4; in this figure the contour colors represent the same value in order to allow for direct comparison. From Figure 4 it is apparent that, in a compact

26

Figure 5. (a) uniform fill density, (b), (c) and (d) two regions with balanced masses

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density in the upper region was 10% higher than that in the lower region (i.e., ρtop = 1.1ρbot), and the mean density remained at 3.09 g/cm3. The configuration shown in Figure 5 (b) was selected since it is reasonable to assume that powder flow into the narrow lower section may be impeded by the air escaping, and by particle bridging. Configuration (c) represents a case similar to configuration (b), with the assumption that a denser state may be obtained at the top of the lower section due to the weight of powder above it. Configuration (d) may be produced as a result of local densification near the top of the die, caused by repeated passes of the feed shoe. The compact density contour plots are shown in Figure 6 and Figure 7. Identical levels for the contour colors were used in all four cases. The compact in Figure 6(a) exhibits normal behavior for double-ended compaction. The regions of lowest density are located along the NP and near the die walls. Regions of higher density are located at the top and bottom punch surfaces near the die walls, where the displacement and wall friction are maximized. The compact in Figure 6(b) exhibits similar features. In the lower narrow region the trends are the same, but the density is lower. The low-density region and the NP occupy a larger area, with the density values being even lower than for the uniform density case. In the upper region the density is much higher than in the uniform case. There is a new region of higher density at the base of the flange, where powder was pushed along the surface of the punch and then around the corner into the lower narrow section. There appears to be little powder flow from the upper section into the lower section of the part. Compacts in Figure 7 exhibit similar density distribution patterns to those in Figure 6(b), but with slightly less pronounced regions of high and low density near the flange–pipe interface. In order to be able to interpret and compare the results, a simpler density distribution diagram is required. In order to construct such a diagram, the density data from the simulation were interpolated onto rectangular zones where the density in each zone was averaged. The final diagrams are presented in Figure 8. In addition to the density variation, Figure 8 includes the punch force levels. The balance is made up from die and core rod forces that have not been included in the tabulation. The density variation between the maximum Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

and minimum was 10.3% of the final average density for the compact with uniform fill density, and 35.2% for the case of nonuniform fill distribution (b). For cases (c) and (d), the density range was 14.8% and 10.5%, respectively. The tool forces acting on the punches are summarized in Table IV. For case (b) there was a 10%

Figure 6. Ferrous powder Dienet geometry compact. (a) uniform die-fill density and, (b) higher initial density in top region (ρtop = 1.1ρbot )

Figure 7. Ferrous powder Dienet geometry compact. (a) higher initial density in top region (ρtop = 1.1ρbot ) with region border in pipe section, (b) higher initial density in top region (ρtop = 1.1ρbot )

Figure 8. Block diagram illustrating density distributions: Dienet compact geometry; Distaloy AE

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TABLE IV. TOOL FORCES: DIENET COMPACT GEOMETRY; DISTALOY AE Uniform Two Regions– Two Regions– Fill Two Regions Lower Border Upper Border Top Punch (kN) 400 442 (+10%) 435 (+8.7%) Lower Outer Punch (kN) -198 -248 (+25%) -240 (+21%) Lower Inner Punch (kN) -228 -210 (-8%) -212 (-7%)

432 (+8%) -236 +(19%) -215 (-5.7%)

subjected to larger volume reduction in comparison with Distaloy AE and Zirconia and thus the compaction ratio was 2.5 while retaining the NP, as shown in Table V. The uniform and nominal die-fill density was set at 3.15 g/cm3. The resultant density distribution is presented in the form of a contour plot in Figure 10. Once the reference model had been analyzed,

increase in the force acting on the top punch and a 25% increase in the force acting on the lower outer punch. The force acting on the lower inner punch was reduced by 8%. This is due to the increased amount of material in the top section of the part. For cases (c) and (d) the increases in top punch force were 8.7% and 8%, respectively. The increases in load on the lower outer punch were 21% and 19%, and the decreases on the lower inner punch were 7% and 5.7%, respectively. Hardmetal Powder Having compared the four die-fill-density configurations for the irregular ferrous Distaloy AE powder it was appropriate to test whether the conclusions are valid for other powders. As noted previously, and demonstrated in a material model validation,15 the compaction behavior of the three powders was different. Configuration (b) was found to result in the most severe final-density variation and was chosen, along with configuration (a), to be simulated again for the tungsten carbide powder. The generic Dienet geometry was used but the dimensions were modified, together with the kinematics, to reflect the axial dimensions of a part that may be manufactured using this powder, Table V. Additionally, a configuration similar to that in Figure 2, with a diagonal interface between the two regions, was explored, Figure 9. In compaction, hardmetal powders are

Figure 9. (a) diagonal and (b) flat region configurations

Figure 10. Hardmetal Dienet compact geometry. Uniform fill density (3.15 g/cm3)

TABLE V. HARDMETAL COMPACT GEOMETRY Nominal Compact Geometry H1 (mm) H2 (mm) Target Press Density Assumed Fill Density Compaction Ratio Part Internal Radius (mm) Fill Geometry H1 (mm) H2 (mm)

10 20 7.8 3.15 2.5 1.0 25 50

NP = neutral plane

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two further configurations of die-fill density were simulated, Figure 11. In each case the die-fill density in the upper region was 110% of the fill density in the lower region, with the average density remaining at 3.15 g/cm3. The results are shown in Figures 11 and 12. In comparing the results it is clear that the pressed-density distribution was significantly more uniform for the compact with uniform fill. Regions of lower density near the NP and higher density near the punches are more prominent for nonuniform die fill. There is also a region of higher density immediately above the pipe–flange interface. The resulting block densities and tool forces are shown in Figure 13, and the attendant tool forces are summarized in Table VI. The density variation between the maximum and

minimum values are now increased significantly in comparison with the behavior of the ferrous powder, achieving 15.9% of the final density for uniform fill, 34.1% for the diagonal border case, and 34.2% for the horizontal border case. There is an increase in the force acting on the top punch of 29% for the diagonal region case and 36% for the horizontal region case. For the lower outer punch the increases in force are 57% and 64%, respectively. The forces acting on the lower inner punch are reduced by 9% and 1.5%, respectively. Although the patterns of density distribution are similar for the ferrous and the hardmetal powders, the percentage increase in the values of the tool forces are different. Consistently, there is an increase in the loads on the punches; however, these are proportionally much larger for the hardmetal powder than for the ferrous powder. This is due to the higher friction coefficient between the die wall and powder and the larger mass of material within the flange part of the die for the hardmetal powder, as reflected in the significant increase in load on the outer lower punch. Ceramic Powder Again, the Dienet compact geometry was used

Figure 11. Final-density distribution in Dienet geometry hardmetal compact with two regions of varying fill density (Figure 10(a))

Figure 13. Density distribution block diagram. (a) uniform fill density, (b) two regions with diagonal border (Figure 9 (a)), and (c) two regions with horizontal border. (Figure 9 (b))

TABLE VI. TOOL FORCES ON PUNCHES: HARDMETAL POWDER; DIENET COMPACT GEOMETRY

Figure 12. Final-density distribution in Dienet geometry hardmetal compact with two regions of varying fill density (Figure 9(b))

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

Top Punch (kN) Lower Outer Punch (kN) Lower Inner Punch (kN)

Uniform Fill

Two Regions– Diagonal

Two Regions– Flat

129 -62 -83

166 (+29%) -98 (+57%) -76 (-9%)

175 (+36%) -102 (+64%) -82 (-1.5%)

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with fill heights identical to those used for the ferrous powder. As before, two compacts, one with a uniform die-fill density (configuration Figure 5(a)) and the other with two regions of different die fill density (configuration Figure 5(b)), were considered. In both cases the mass of powder was the same. Double-ended compaction was used with a compaction ratio of 2.2. The density contour plots for both simulations are presented in Figure 14 and the corresponding block diagrams in Figure 15.

Figure 14. Ceramic powder Dienet geometry compact. (a) uniform fill density, and (b) higher initial density in top region

Figure 15. Block diagram of density distribution in ceramic powder; Dienet compact geometry. (a) uniform fill density, (b) higher initial density in top region

30

TABLE VII. TOOL FORCES ON PUNCHES: CERAMIC POWDER; DIENET COMPACT GEOMETRY Top Punch (kN) Lower Outer Punch (kN) Lower Inner Punch (kN)

Uniform Fill

Two Regions

699 -359 -366

805 (+15%) -488 (+36%) -332 (-9%)

Similar behavior to the other powders is observed for this geometry. For the nonuniformfill part the lower section density is lower overall. The region of low density near the NP is higher, with a lower minimum density. There is a general increase in density in the flange region and an area of high density immediately above the flange–pipe interface. The variation between the maximum and minimum densities in the compact is 8.3% of the final density for the compact with uniform fill density, and 28.9% for the multiregion case. The tool forces acting on the punches are summarized in Table VII. There is a 15% increase in the force acting on the top punch, and a 36% increase in the forces on the lower outer punch. The force acting on the lower inner punch are reduced by 9%, due to the increased amount of material in the top section of the part, consistent with the trends reflected in the other powder types. Modnet Geometry The Modnet stepped geometry differed from the Dienet geometry in that the lower section was on the outside of the part, rather than on the inside. This is significant since more volume is occupied by the lower section of the Modnet part than that of the Dienet part. As the upper section of the die is expected to have a higher density, some of the powder from the top section is transferred to the lower section. Thus, in the case of the Modnet geometry there is more capacity to accommodate powder transfer than in the Dienet geometry, as illustrated in Figure 16. Similar fill configurations were used for the Modnet geometry, namely, uniform die-fill density for the first model and the second model, with two regions of differing fill density, balanced to produce the same mass compact as in the uniformfill case. Again, the difference between the density in the upper and lower parts was taken to be 10%. The border between the regions and the NP was along the top surface of the inner lower Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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punch, Figure 17. Double-ended kinematics were used in both cases with a compaction ratio of 2.0. The results are shown in Figure 18 and Figure 19. As with the Dienet geometry, the part with the uniform-fill density exhibits a smaller variation in density. Most of the part appears to exhibit essentially a uniform density with regions of high density in the areas of contact between the top and bottom punches and die walls. The block diagram in Figure 19(a) shows this uniformity in the density distribution, with only the bottom section of the tube being significantly denser than the remainder of the compact. However, the density of the compact with variations in fill density is much less uniform in the pressed state. The lower-density region near the NP is significantly more pronounced, and the density in the upper region is

significantly higher, overall. This is apparent from both the contour plot and the block diagram. As a result of the nonuniform fill condition there is an increase of 6.4% in the load on the top punch, a decrease of 15% in the load on the lower punch, and an increase of 13.6% in the load on the lower inner punch. DISCUSSION This study has assessed the impact of die-filldensity distribution on pressed density. It has been demonstrated that for simple shapes, such as hollow cylinders, variations in die-fill density along the direction of compaction do not affect the final pressed-density distribution significantly in the compacted part. However, for more complex

Figure 18. Ferrous powder Modnet geometry compact. (a) uniform fill density, (b) higher initial density in top region (ρtop = 1.1ρbot )

Figure 16. Possible powder transfer direction in Dienet and Modnet compact geometries

Figure 17. Modnet geometry fill conditions; ferrous powder

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

Figure 19. Block diagram of density distribution: ferrous powder Modnet geometry compact. (a) uniform fill density, (b) higher initial density in top region (ρtop = 1.1ρbot )

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multilevel geometries, the differences in both the final-density distribution and tool forces are significant. Typically, the range of densities in the final compact are higher, with more extreme maximum and minimum densities. This has implications in relation to sintering shrinkage in hardmetal and ceramic parts, and the mechanical performance of ferrous parts. Where die-fill densities are higher in the upper region, forces on the top and the lower outer punch of the Dienet geometry part are also found to increase significantly. This may lead to a reduced lifespan of the punch or, in extreme cases, failure. The percentage increase varies for different powders and is most significant for tungsten carbide, because the latter powder is the most compressible and exhibits a rapid build-up of stress towards the end of the compaction process. When combined with the larger displacement required to compress this powder, it leads to a significant increase in stress levels on the tool set. The different density levels achieved in each powder prohibit direct comparisons. However, some common features are observed in all three compacts. There is an area of low density, designated “1” in Figure 20, just below the level of the lower outer punch. This is the area most distant from the top and bottom punches; the presence of a low density area in this location agrees well with predictions. There is a region of higher density common to all three compacts, designated “2,” which connects the tip of the lower outer punch to the top right corner of the compact. It is difficult to compare the intensity of zone “2” between the different compacts because of the varying densities and contour color indexing. Section “3” is a region of higher density which is caused by

Figure 20. Comparison of density distributions. (a) ceramic, (b) ferrous, (c) hardmetal powders (nonuniform fill condition, border region at the level of the lower outer punch)

32

friction between the tools and the powder. This is a feature commonly seen in compacts. At the lower end of area “2,” marked “4,” there is a local region of high density which is again common to all three compacts. The high-density area marked “5” is a common feature in all three compacts and, like feature “3,” correlates well with predictions from experience. The features cited are also present in the density distribution of the Modnet geometry compact, Figure 21. The region of lower density “1” is located immediately below the level of the lower inner punch. There is a band of higher density, designated “2,” which connects the inside top of the compact with the tip of the lower inner punch. However, there is not a prominent region of high density around point “4,” unlike the compacts with the Dienet geometry. This is expected because the top part of the Modnet geometry compact is bulkier. The difference between the initial density in the top section and the mean fill density is smaller for the Modnet geometry compact than for the Dienet geometry compact, in order to maintain the 10% top-to-bottom variation because of the relative volumes occupied by the top and bottom sections in each compact. The size of the top section of the Modnet geometry compact also results in a smaller distribution as the powder is less constrained. The high-density areas “3” and “5” are also less pronounced. The former because the fill density is low in the lower section, and the latter because the powder in the top section is less constrained, allowing for a more uniform density distribution than in the Dienet geometry compact.

Figure 21. Density distribution in green Modnet geometry compacts; ferrous powder. (a) uniform fill, (b) nonuniform fill

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CONCLUSIONS Three powders were used to conduct a sensitivity study on the effect of die-fill density on diepressing performance for a range of compact geometries. Simple ring geometries were found to be unaffected by variations in die fill density in the axial direction. As examples of multilevel parts, final-density distributions for flanged geometries (both internal and external flange) proved to be less uniform for a nonuniform die fill density. A fill-density variation of 10% led to variations in final pressed density of up to 35%, compared with 10% for the uniform-fill case. Tool forces were found to be markedly influenced by density variation, achieving up to 64% increase on some tools. The magnitude of the increase depended on the variation in fill density within the cavity and the powder type being compacted. ACKNOWLEDGEMENTS This work was funded by AEA Technology as part of the "Minimizing Density Variations in Powder Compacts" project for DTI’s Materials Metrology program. Appendix A: Definition of Material Model The material model was defined using an instrumented-die test in which a cylindrical powder compact is pressed, and for which the stress state is axisymmetric. The hydrostatic and deviatoric stresses defined as P and Q are given by: P = (σz + 2σr)/3

(A.1)

Q = σz – σr

(A.2)

For a Cam-Clay material model: 2 σdz + 2σdr ————— – P0 3 (σdz + 2σdr )2 f = ———————— + ————— –1 = 0 (A.3) P20 Q20

(

)

where σ dz and σ dr and are the axial and radial stresses, respectively, during die pressing In the absence of additional information, it is commonly assumed that the model is associated and therefore the plastic strain-rate tensor can be expressed as: · ε· pij = λ (∂f/∂σij)

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

(A.4)

For a die that is perfectly rigid, there is no radial displacement during pressing. Thus, the plastic radial strain will be zero at all times; this implies that: (∂f/∂σij)i=j=r = 0

(A.5)

Applying equations A.4 and A.5 to equation A.3 results in: σdz + 2σdr

–P ) (————— 3

0 2 (σdz + 2σdr ) ∂f/∂σij = — ———————— + ————— = 0 (A.6) 3 P20 Q20

From equations A.3 and A.6, the functions P0 and Q0 are obtained as:

(

2

)

3Pd + 2PdQd P0 = ——————— 6Pd + 2Qd

Q0 =

(A.7)

3 (Pd)2 Qd — 2 2 Qd + —————— 2 Qd 2Pd + — 3

(A.8)

Therefore, for known values of and, Pd and Qd can be calculated. Subsequently P0 and Q0 can be obtained and curve fitted as functions of the density field. The functions are chosen to fit the form of the experimental data and to satisfy limiting conditions. There are four unknowns K1 to K3 and Qmax: ρ – ρ0 P0 – K1 ln – ———— ρ – ρmax

( (

)) )

K3P0 Q0 = Qmax tanh ——— Qmax

(

K

2

(A.9)

(A.10)

The experiment allows the determination of diewall friction. Further material model data comprise elastic parameters. Although these are not particularly important in compaction, they must be supplied to complete the material data set. The full set of material data parameters used is given in Table A.1, including the initial and theoretical maximum density. REFERENCES 1. J.E. Peterson and W.M. Small, “Evaluation of Metal Powders Using Arnold Density Meter and Hall Flowmeter”, Powder Metallurgy, 1994, vol. 37, no. 1, pp. 37–41. 2. D.M.M. Guyoncourt and J.H. Tweed, “Measurement of

33

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TABLE A.1 MODEL PARAMETERS Distaloy AE Powder Qmax 271.05

K1 60.45

K2 1.311

K3

ρ0

ρ^

E

ν

µ

1.8

3.10 g/cm3

7.4 g/cm3

8.0E + 04N/mm2

0.3

Variable1

ρ^

E

ν

µ

0.3

0.16

Tungsten Carbide–Cobalt Powder Qmax

K1

K2

K3

ρ0

625.85

102.72

3.368

1.702

3.20 g/cm3

K1

K2

K3

ρ0

ρ^

E

ν

µ

3.37

1.2 g/cm3

3.6 g/cm3

8.0E + 04N/mm2

0.3

Variable1

11.83 g/cm3 8.0E + 04N/mm2

Zirconia Powder Qmax 18000.0

150.0

1.5

1. Friction varied from 0.12 at zero normal stress to 0.05 at 250 MPa as a quadratic function

3.

4.

5.

6.

7.

8.

34

Powder Flow”, AEA Technology Report, 2003, Atomic Energy Authority, Harwell, Didcot Oxfordshire, UK, 2003. W.J. Ullrich, “Powder Flow Measurement Techniques: What’s New?”, Advances in Powder Metallurgy and Particulate Materials, compiled by J.J. Oakes and H.H. Reinshagen, Metal Powder Industries Federation, Princeton, NJ, 1998, vol. 1, part 4, pp. 107–127. E. Hjortsberg and B. Bergquist, “Filling Induced Density Variations in Metal Powder”, Powder Metallurgy, 2002, vol. 45, no. 2, pp. 146–153. A.C.F. Cocks, L. Dihoru and T. Lawrence, “A Fundamental Study of Die Filling”, EURO PM2001: 2001 European Congress and Exhibition on Powder Metallurgy, Nice, France, published by the EPMA. C-Y Wu, L. Dihoru, O.T. Gillia and D.A. Thompson, “The Flow of Powder into Simple and Stepped Dies”, Powder Technology, 2003, vol. 134, pp. 24–39. J. Haskins and W. Jandeska, “Powder Flow and Die Filling Studies using Computed Tomography”, Advances in Powder Metallurgy and Particulate Materials, compiled by J.J. Oakes and H.H. Reinshagen, Metal Powder Industries Federation, Princeton, NJ, 1998, vol. 3, part 10, pp. 77–87. S.F. Burch, J.H. Tweed, A.C.F. Cocks, I.C. Sinka and C-Y Wu, “Measurement of Density Variations in Compacted Parts and Filled Dies using X-ray Computerised Tomography”, Powder Metallurgy World Congress &

9.

10.

11.

12.

13.

14. 15.

Exhibition PM2004, edited by H. Danninger and R. Ratzi, European Powder Metallurgy Association, Shrewsbury, UK, 2004, vol. 5, pp. 393–398. O. Coube, A.C.F. Cocks and C-Y Wu, “Experimental and Numerical Study of Die Filling, Powder Transfer and Die Compaction”, Powder Metallurgy, 2005, vol. 48, no. 1, pp. 68–76. C-Y Wu, and A.C.F. Cocks, “Flow Behaviour of Powders During Die Filling”, Powder Metallurgy, 2004, vol. 47, No. 2, pp. 127–136. PM Modnet Computer Modelling Group, “Comparison of Computer Models Representing the Powder Compaction Process”, Powder Metallurgy, 1999, vol. 42, no. 4, pp. 301-311. L.C.R. Schneider, A.C.F. Cocks and A. Apostolopoulos, “Comparison of Filling Behaviour of Metallic, Ceramic, Hardmetal and Magnetic Powders”, Powder Metallurgy, 2005, vol. 48, no. 1, pp. 77–84. P. Brewin and L. Federzoni, “Dienet: Conclusions and Achievements”, Powder Metallurgy, 2006, vol. 49, no. 1, pp. 8–10. S.F. Burch, Unpublished results from the MPM5.2 project, AEA Technology, 2004. D. Korachkin, “Measurement Methods for the Determination of Powder Properties for Compaction Modelling”, PhD Thesis, University of Wales, 2006. ijpm

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RESEARCH & DEVELOPMENT

HIGH-DENSITY INCONEL 718: THREEDIMENSIONAL PRINTING COUPLED WITH HOT ISOSTATIC PRESSING José Sicre-Artalejo*, Frank Petzoldt**, Mónica Campos*** and José M. Torralba****

INTRODUCTION Nickel–chromium-base superalloys exhibit a wide range of mechanical properties, with excellent corrosion resistance, oxidation resistance, and resistance to damage-inducing mechanisms that operate at high temperatures.1,2 Since superalloys are utilized in high-performance applications, it is important to develop new cost-effective production methods. This study evaluates the capability of the 3DP process to fabricate parts from nickel-base superalloy powder. Utilizing this technique, large complex green parts can be fabricated from metallic powders in a time frame of hours.3 3DP is a process in which parts are created directly from computer models.1 A solid object is created by printing a sequence of two-dimensional layers. The formation of each layer involves the spreading of a thin layer of powder, followed by the selective joining of the powder in the layer by ink-jet printing of a binder material. These printed parts do not reach their pore-free density after sintering, and post-sintering treatments such as HIPing are required. If the printed parts exhibit closed porosity after sintering, encapsulation prior to HIPing can be avoided.

The feasibility of fabricating high-density parts from Inconel 718 powder using three-dimensional printing (3DP) was assessed. Parts were subsequently hot isostatically pressed (HIPed) to achieve full density. After optimization of the particlesize distribution, parts were fabricated by means of the 3D-printing process utilizing two different devices in order to examine the influence of the binder. Printed parts were sintered in high vacuum at 1,563K (1,290°C) or 1,573K (1,300°C) and characterized in terms of density and microstructure. Finally, sintered parts were HIPed at 1,473K (1,200°C) and 142 MPa, followed by a second HIPing cycle at 1,483K (1,210°C) and 206 MPa for 3 h in argon to achieve full density.

EXPERIMENTAL PROCEDURE Gas-atomized Inconel 718 powder of two different sizes was used (Table I and the scanning electron microscope (SEM) images in Figure 1). The nominal composition of the alloy is listed in Table II. To enhance the 3DP process, coarse and fine powders were blended to increase both the apparent density and tap density. The coarse powder was blended with different amounts of fine powder ranging from 10 w/o to 100 w/o of fine powder. Application of the 3DP process with powder blends exhibiting a high tap density was expected to enhance the sintered part density. The powders were blended in a Turbula™ *PhD Student, ***Lecturer, ****Professor, Universidad Carlos III de Madrid, Department of Materials Science and Engineering, Avda. Universidad 30, E-28911 Leganés, Madrid, Spain; E-mail: [email protected], **Head of Department of Powder Metallurgy, Fraunhofer IFAM, Wiener Strasse 12, D-28359 Bremen, Germany

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HIGH-DENSITY INCONEL 718: THREE-DIMENSIONAL PRINTING COUPLED WITH HOT ISOSTATIC PRESSING

TABLE I. PARTICLE-SIZE DISTRIBUTION OF POWDER

TABLE II. CHEMICAL COMPOSITION OF POWDER (w/o)

Fine Powder (F)

Coarse Powder (C) *

Ni

10 w/o 50 w/o 90 w/o

1.8 w/o +53 µm 98.2 w/o -53 µm

52.6 18.8 Bal. 5.3

-6.1 µm -12.8 µm -21.8 µm

Cr

Fe Nb(+Ta) Mo Ti

Mn Al

Si

Other Elements (Max)

3.2 0.93 0.12 0.49 0.28 0.08 C, 0.006 B, 0.015 S, 0.015 P, 0.30 Cu

* Based on ASTM B 214

Figure 1. As-received superalloy powders: (a) coarse powder, (b) fine powder. SEM/secondary electron images

model T 2F mixer at a moderate speed for 45 min. Thermomechanical analysis (TMA) was utilized to monitor the changes in volume expansion of the alloy, as affected by the proportions of coarse and fine powder in the blends. TMA analyses were conducted in the expansion mode on a Perkin-Elmer TMA thermomechanical analyzer under an atmosphere of flowing argon. Powder samples (5 mm in height) were heated from 303K (30°C) to 1,598K (1,325°C) at 10 K min-1 with a dwell time of 1 h and then cooled to 303K (30°C) at 10 K min-1. The experiment was performed without the application of force to monitor changes in length due to the thermal cycle. This resulted in a similar response to that observed utilizing dilatometry. After characterization of the powders, the 3DP process was initiated. Two different 3D-printing devices were used, namely Prometal™RTS-300 and Prometal™RX-1 (hereafter referred to as 3DP1 and 3DP-2, respectively). The two devices are based on the same functional principle, but a different binder was used in each process. The printing device consisted of two boxes, the reservoir box and the build box. The powder was spread

36

from the reservoir to the build box creating a layer of powder with the desired thickness. Subsequently, the nozzles in 3DP-1 or inkjets in 3DP-2 deposited the binder, as dictated by the CAD model. In both 3DP processes, the thickness of the powder layer was ~125 µm.4 Once the powder layer was printed, it was dried for 20 s in the 3DP-1 device, and for 50 s in the 3DP-2 device. Each 3DP device used a specific polymeric commercial binder, namely Primal WS-24E and PM-BSRX for 3DP-1 and 3DP-2, respectively. The difference in the two binders arises from the deposition mechanism(s) operative in each device. The amount of binder in the final material was ~10 v/o; it was deposited at a rate of 2 layers per min for the prototype geometry selected. The resulting 3DP green parts were sintered under a high vacuum of 4.05 x 10-10 MPa (4 x 106 mbar) at 1,563K (1,290°C) or at 1,573K (1,300°C) for 2 h in a single-step sintering process. Two different heating rates were examined, namely 5 K/min and 10 K/min, to monitor the possible influence of debinding on sintered properties. Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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Characterization of the printed parts included an evaluation of the shrinkage after sintering and the density, as determined by the Archimedes’ immersion (ethanol) method. Microstructures were analyzed by means of light optical microscopy (OM) and SEM. Samples for metallographic analysis were prepared following standard techniques: progressive silicon carbide grinding, surface polishing (3 µm diamond paste), and electrolytic etching in 5 w/o oxalic acid. Sintered parts were HIPed in a model AIP6-30H press (American Isostatic Presses, Inc.). The first HIPing cycle was 1,473K (1,200°C) under 146 MPa for 3 h, as previously reported.10 Both heating and cooling rates were 10K/min. The microstructures of the HIPed parts were analyzed using LOM and SEM. The final density was measured by means of a helium pycnometer. After analyzing the density and microstructure, a second HIPing cycle was imposed, which consisted of heating to 1,483K (1,210°C) under 206 MPa for 3 h in argon, using the same heating and cooling rates as in the initial cycle. Samples for metallographic analysis were prepared using the following standard techniques: progressive silicon carbide grinding, surface polishing (3 µm diamond paste), and etching in Kalling’s reagent.5 RESULTS AND DISCUSSION Optimization of Powder Mixtures To optimize the 3DP process, a particle size similar to the layer thickness of the printed mate-

Figure 2. Effect of addition of fine powder to coarse powder on particle-size distribution

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

rial is necessary (in this case ~100 µm). When considering the particle size of the powders, optimization of the particle-size distribution is also necessary. This was accomplished by evaluating blends of the fine and coarse powders from 100 w/o coarse (C) to 100 w/o fine (F). As seen in Figure 2, the size distribution shifts slightly to smaller sizes when the level of fine powder added increases from 0 w/o to 30 w/o. Figure 3 shows the influence of particle-size distribution on apparent density and tap density. Since the powder is spread over the preceding powder layer during the 3DP process, it is important to know how much material was deposited. To this end, tap density was monitored as a function of the particle-size distribution of the powder blends, since apparent density is strongly affected by particle size; it decreases as the particle size of the blend decreases.6 In contrast, a convincing explanation cannot be provided for the changes in tap density that result from adding fine powder to coarse powder. Since the 30F70C and 20F80C powder blends exhibited the highest tap densities of all the samples, they were printed along with 100C powder as a reference. Another criterion for selection of the powder blends to be printed is based on thermal analysis. Powder blends with lower amounts of fine powder exhibited between 13% and 16% unidirectional shrinkage, as shown in Figure 4. In addition to apparent density and shrinkage, it is also necessary to recognize that powder blends with higher levels of fine powder (80F20C and 90F10C powder blends) are not suitable for 3DP.7,8

Figure 3. Effect of increasing the level of fine powder in blends of coarse and fine powder on apparent density and tap density

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Figure 4. Shrinkage of powder blends at 1,598K as a function of particle-size distribution

3DP Processes Based on previous work7 on the 3DP process using 3DP-1, incompatibility of the 100C powder

with the binder, was expected, due to its small particle-size distribution. Initially, 100C powders were printed which resulted in a lack of wetting during printing of the first layers. In consequence, binder droplets were present confirming incompatibility between the binder and metal powder. However, after the first five layers were printed, the process continued successfully. Figure 5(a) shows a printed layer of IN-718 coarse powder in which deficiencies in the 3DP process are evident. The next sample tested was a 20F80C powder blend. Lack of wetting by the binder at the onset of the process was more severe in this case, as seen in Figure 5(b). Large drops of binder remained without wetting of the powder. The 3DP process was enhanced by optimizing the spreading speed (slower rate) and increasing the curing time, as seen in Figure 5(c). Finally, 30F70C powder blends were printed. In the absence of wetting by the binder, 3DP was not possible. The binder droplets were large, as seen in Figure 5(d). Under these conditions, each

Figure 5. Photographs of 3DP process utilizing Prometal™RTS-300. (a) 100C powder, (b) and (c) 20F80C powder blend, (d) 30F70C powder blend

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box bed containing the powder. The temperature of the build-box bed was 80°C, whereas it should have been 150°C. To prevent energy loss, a ceramic plate was placed on the base of the build box which increased the temperature of the build-box bed to 130°C. In this model, more accurate shapes were obtained, although the shapes were still not perfect. The printing performance of the 100C powder and the 30F70C powder blend was significantly better than that of the 20F80C powder blend. The latter exhibited stability problems both during and after curing. The other two powder blends could be printed, with no shape distortion. Figure 6. Sintered samples: (a) correct 3DP conditions on blend 100C, (b) skewed profile from lack of binder wetting. Powder blend 20F80C

layer did not spread over the previous layer. The particle-size distribution of this powder blend was small, reducing the compatibility of the binder and the metal powder. Utilizing the 3DP-2 printer, the binder did not cure sufficiently in the first printed layer. This resulted in a small misplacement of the subsequent layers, and a skewed sample profile, as illustrated in Figure 6. The skewed profiles are attributed to heat-flow losses through the build-

Sintering of Printed Parts Figure 7 shows the influence of the process parameters studied on the density of the as-sintered printed parts, and on shrinkage after sintering. As expected, the as-sintered density increased as the sintering temperature increased and the heating rate decreased. In both cases, higher densities were achieved with the 20F80C powder blend after sintering at 1,563K (1,290°C) and 1,573K (1,300°C). The presence of fine powder in the powder blend enhances densification during sintering due to the higher particle sur-

Figure 7. Effect of heating rate, sintering temperature, and binder type on relative density and shrinkage of powder blends. (a) 3DP-1 mode, (b) 3DP-2 mode, (c) 3DP-1 mode, and (d) 3DP-2 mode

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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face:volume ratio, which increases the driving force for sintering. A high density was obtained and complete densification appears to be a viable target for this powder blend. Nonetheless, porosity is still evident, but is less for 3DP-2 than for 3DP1, as seen by comparing Figure 8 and Figure 9. Characterization of the microstructures of the 3DP-1 parts shows that the phases present vary with the sintering temperature. The heating rate, or the proportions in the powder blends, do not influence the resulting microstructures. Notwithstanding discrepancies in the literature concerning the precipitation kinetics in Inconel 718, the primary microstructural effects on mechanical properties in this alloy system are attributed to the presence of γ’ (intermetallic Ni3TiAl) precipitates, and to γ" (intermetallic Ni3Nb) precipitates which are unstable >923K (650°C) and are associated with the presence of iron. Parts sintered at 1,563K (1,290°C) exhibit a high density of small γ" precipitates, and a smaller

number of scattered γ’ precipitates (circled in Figure 8). At 1,573K (1,300°C), micrographs exhibit large pores which appear to be the result of overheating during sintering. This reflects an excessive presence of liquid phase during sintering, which could not rediffuse into the solid particles. Literature on the sintering of Inconel includes evidence of a liquid phase >1,463K (1,190°C).9,10 Thus, there will always be a small amount of liquid present which favors mass transport mechanisms leading to higher densification, at the chosen sintering temperatures. However, if the amount of liquid formed is excessive, it could be detrimental to properties because of rediffusion. Based on the microstructures of the sintered 3DP-2 parts major changes are observed compared with 3DP-1. First, the expected quantities of γ’ and γ" precipitates (circled in Figure 9) appear at 1,563K (1,290°C).11 Second, sintering temperature does not affect the final microstructure sig-

Figure 8. Representative microstructures of 20F80C powder blend: (a) and (b) sintered at 1,563K, (c) sintered at 1,573K with heating rate 5 K/min and 3DP-1 mode. OM

Figure 9. Representative microstructures of 100C powder (a) sintered at 1,563K, heating rate 5K/min, (b) sintered at 1,573K and 5K/min, and (c) sintered at 1,563K, heating rate 10 K/min and 3DP-2 mode. OM

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nificantly. As with 3DP-1, the sintering temperature does not change the number of precipitates, only their size and amount. The level of porosity

Figure 10. Pore-free density (%) of 3DP parts for two powder blends after HIPing at 1,473K and 146 MPa for 3 h

Figure 11. Representative micrograph of HIPed sample 20F80C (1,473K and 146 MPa for 3 h) showing porosity. SEM/backscattered electron image

Figure 12. Density of sintered 3DP parts for two powder blends after HIPing at 1,483K and 206 MPa for 3 h

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

decreases significantly as the proportion of fine powder in the powder blend increases. Specifically, with 20 w/o and 30 w/o of fine powder, pores and grains are round, which suggests that sintering occurred during the final stage. Hot Isostatic Pressing The densification that occurred after the first HIPing cycle is shown in Figure 10. Complete densification of the two powder blends was not achieved. From Figure 11 it is observed that pores remain that were not closed during the first HIPing cycle. Subsequently, a second HIPing cycle was imposed. To attain maximum process efficiency, four samples with the highest as-sintered densities for both binders were selected. As observed in Figure 12, the pore-free density (8.19 g/cm3) of Inconel 718 was reached after the this second HIPing cycle, for samples with different initial assintered densities. The variation in density of the as-HIPed specimens was within the range of the deviation associated with the precision of the equipment. The HIPing cycles were performed in an argon atmosphere. This procedure superficially oxidized the parts but did not affect the internal microstructure, as seen in Figure 13. These SEM images also confirm the absence of porosity, and hence the achievement of the pore-free density of the superalloy. CONCLUSIONS 1. The binder used in the 3DP process, and the binder deposition device, influence the final density, microstructure and the shape profile of the sintered parts. 2. Comparing the two processes, 3DP-1 resulted in printed parts with superior shape stability and a higher final sintered density than 3DP-2, but with different microstructures. The latter mode resulted in excellent microstructures and properties, but inferior shape stability. 3. Sintering temperature had a significant effect on the final microstructure in the 3DP-1 mode, but had little effect in the 3DP-2 mode. 4. The optimal sintering parameters were 1,563K (1,290°C) for 2 h in vacuum with a heating rate of 5 K/min; this resulted in sintered density levels ~97% of the pore-free value. 5. No differences were found in the size or the distribution of γ’ precipitates after sintering or HIPing. However, the homogeneity in the distri-

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Figure 13. Representative micrographs illustrating fully dense printed and sintered parts. (a) and (c) 3DP-1 mode of 100C , (b) and (d) 3DP-2 mode of powder blend 30F70C. SEM/backscattered electron images

bution of the γ" precipitates improved after HIPing. 6. It is possible to fabricate fully dense 3DP parts using HIPing. Pore-free density was achieved in parts printed in both the 3DP-1 and 3DO-2 modes. There is no significant influence of binder type after HIPing, from particle size, or from sintering temperature on HIPing response. The HIPing parameters that resulted in pore-free density were 1,483K (1,210°C) and 206 MPa for 3 h. It is expected that other combinations of HIPing parameters would result in pore-free density of the superalloy parts. ACKNOWLEDGEMENTS The authors thank Dr. Monge, Department of Physics, Carlos III University of Madrid, for providing the equipment necessary to complete this project.

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REFERENCES 1. D. Godlinski and H. Pohl, “Rapid Manufacturing of Dense Stainless Steel Parts by 3D-Printing”, Euro PM 2003, European Powder Metallurgy Association, Shrewsbury, UK, 2003, vol. 2, pp. 131–136. 2. A. Thomas, M. El-Wahabi, J.M. Cabrera and J.M. Pardo, “High Temperature Deformation of Inconel 718”, Journal of Materials Processing Technology, 2006, vol. 177, pp. 469–472. 3. D. Dimitrov, “Advances in Three Dimensional Printing— State of the Art and Future Perspectives”, Rapid Prototyping Journal, 2006, vol. 12, no. 3, pp. 136–147. 4. D. Godlinski and G. Veltl, “Three Dimensional Printing of PM-Tool Steels”, Euro PM 2005, European Powder Metallurgy Association, Shrewsbury, UK, 2005, vol. 3, pp. 49–54. 5. Y. Murata, M. Morinaga, N. Yukawa, H. Ogawa and M. Kato, “Solidification Structures of Inconel 718 with Microalloying Elements”, 3rd International Special Emphasis Symposium on Superalloys 718, 625, 706 and Various Derivatives, edited by E.A. Lorea, The Minerals, Metals & Materials Society, Warrendale, PA, 1994, pp. 81–88.

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6. ASM Handbook, Powder Metal Technologies and Applications, vol. 7, Ninth Edition, 1998, ASM International, Materials Park, OH. 7. M. Turker, D. Godlinski, H. Pohl and F. Petzoldt, “Rapid Prototyping of Inconel Alloys by Direct Metal Laser Sintering and Three Dimensional Printing”, ibid reference no. 4, vol. 3, pp. 93–98. 8. D. Godlinski and S. Morvan, “Steel Parts with Tailored Materials Gradients by 3D-Printing Using NanoParticulate Ink”, Mater. Sci. Forum, 2005, vols. 492–493, pp. 679–684.

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

9. K. Hajmrle and R. Angers, “Sintering of Inconel 718”, Int. J. Powder Metall. & Powder Tech., 1980, vol. 16, no. 3, pp. 255–266. 10. G. Appa Rao, M. Srinivas and D.S. Sarma, “Effect of Solution Treatment Temperature on Microstructure and Mechanical Properties of Hot Isostatically Pressed Superalloy Inconel 718”, Mater. Sci. Tech., 2004, vol. 20, pp. 1,161–1,170. 11. S. Azadian, “Aspects of Precipitation in Alloy Inconel 718”, 2004 PhD Thesis, Luleå University of Technology, Sweden. ijpm

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ENGINEERING & TECHNOLOGY

ECONOMICS OF PROCESSING NANOSCALE POWDERS John L. Johnson*

INTRODUCTION Despite predictions for widespread use of nanoscale powders (consisting of particles with dimensions <100 nm), their implementation via press-and-sinter processing remains limited. Powder cost, contamination, handling difficulties, low packing densities, and rapid grain growth during sintering all present barriers to their use. Prior models1,2 for nanoscale tungsten identified a potential processing path utilizing clean powders, ultrahigh compaction pressures (>1 GPa), and low sintering temperatures that preserve nanosized grains. Such new processes must show a substantial cost or performance benefit in order to displace established powder metallurgy (PM) press-and-sinter processes. This paper extends the sintering and property models for nanoscale tungsten to other metals and ceramics and considers the processing economics through analysis of powder costs, compaction costs, and sintering costs in comparison with the performance benefits. These models are not meant to be scientifically rigorous, but do show trends that provide clear guidance in the economic utilization of nanoscale powders.

Nanoscale powders can enhance densification and enable sintering of components at lower-thanconventional temperatures with refined microstructures. However, nanoscale powders often come at a cost premium and retention of nanosized grains after processing is difficult. In this paper, sintering models developed for nanograined tungsten are extended to other metal powders and ceramics to predict sintered densities and grain sizes for various compaction pressures, sintering temperatures, and sintering times. Property maps are developed as functions of the initial particle size. The properties are then normalized based on powder cost to identify the particle sizes and compositions that provide optimal price/ performance value.

SINTERING MODEL Following the approach of German and Olevsky,1,2 a sintering model was constructed to calculate the apparent density, green density, sintered density, and grain size as functions of particle size. The sintered density and grain size are then used to predict properties. Apparent Density The high surface area and interparticle friction of nanoscale powders result in agglomeration and low packing densities.3 The dependence of the fractional apparent density ρA on the particle size can be expressed by the relation: log ρA = log ρ0 + a log D

(1)

where ρ0 is the fractional packing density of a 1 µm powder, a is a constant, and D is the median particle size in µm. Particle shape and surface condition impact the packing behavior, so each powder is different. In this analysis, values of 0.143 for ρ0 and 0.21 for a were used, based on values derived from tungsten particle-packing data.1,2

Presented at PowderMet2007 and published in Advances in Powder Metallurgy & Particulate Materials—2007, Proceedings of the 2007 International Conference on Powder Metallurgy & Particulate Materials, which are available from the Publications Department of MPIF (www.mpif.org).

*R&D Director, ATI Alldyne, 7300 Highway 20 West, Huntsville, Alabama 35806, USA; E-mail: [email protected]

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Green Density The density of metallic nanoscale powders increases with compaction pressure, but the rate of densification declines with increasing pressure as the particles work harden. Densification also decreases with the hardness of the particles. For tungsten powders, the fractional green density ρg can be expressed by the empirical equation:3

( (

1.545 P ρg = 1 + ρA 1-exp ——— -— D1/7 C

))

(2)

where ρA is the fractional apparent density, D is the median particle size in µm, P is the compaction pressure in MPa, and C is a function of material strength. In this paper, C is estimated as nine times the annealed hardness H0 of the porefree material. Sintered Density The sintered density ρs depends on the green density ρ g and the linear sintering shrinkage ∆L/Lg in conformity with the relation: ρg ρs = ————— 3 ∆L 1- —— Lg

(3)

( )

The sintering shrinkage displays an asymptotic characteristic as the compact nears full density. Following the master sintering curve treatment of Su and Johnson,4 this behavior can be represented by a sigmoid function as given by the relation: f2 ∆L —— = f1 + ———————— Lg f3 - Y 1 + exp ——— f4

( )

(4)

where f1 = 0.01, f2 = 0.165, f3 = 0.104, f4 = 0.015, and Y is a densification factor that can be calculated from an Arrhenius-type equation, namely: 1 Y = —— exp Dv

(

Q Bstw - —— T

)

(5)

where D is the particle size, w and v depend on the diffusion mechanism, Bs is a material parameter, t is the sintering time, Q is the activation energy for diffusion,* and T is the sintering temperature. For tungsten, BS = 0.0054, Q = 3652, v = 0.44, and w = 0.33 when the particle size D is in µm, temperature T is in K, and time t is in minVolume 44, Issue 1, 2008 International Journal of Powder Metallurgy

utes.1,2 In the current study, the densification factor for other materials was predicted by substituting an appropriate activation energy, but leaving the other terms constant. Grain Growth The final grain size G depends on peak sintering temperature, hold time, initial grain size, and the effects from porosity and pore drag in conformity with the relation:5 ρg G = D + Kt1/3 ——— 1- ρs

1/2

( ) ( ) -QG exp ——— T

(6)

where D is the initial particle size, K is a collection of material constants, t is the isothermal time at absolute temperature T, ρg is the fractional green density, ρS is the fractional sintered density, and QG is the activation energy for grain growth.* For tungsten, K = 23.5 µm/s 1/3 and Q G = 11,430 when time is in s, temperature is in K, and grain size is in µm. In this paper, the grain size for other materials was predicted by substituting an appropriate activation energy, but leaving K constant. As an example of the model predictions, the green density, sintered density, and grain size are plotted in Figure 1 as functions of particle size for two different cases. In the first case, the tungsten powder is pressed at 250 MPa and sintered at 2,000°C for 60 min. The low apparent density of nanoscale powders results in a low green density, which cannot be sintered to high density. The density also decreases with large particles due to their slower sintering kinetics, leaving an optimal particle-size range of 1 to 3 µm for near-full density. The grain size of nanoscale powders sintered at 2,000°C is substantially larger than the initial particle size. In the second case, a pressure of 1,280 MPa is used to compact the tungsten powder. A much higher green density is attained and nanoscale powders are predicted to sinter to nearfull density at only 1,000°C, while preserving a refined grain structure. In both cases, once the particle size becomes too large to press and sinter to full density at the specified conditions, grain growth becomes negligible and the grain size is determined by the initial particle size. In general, the properties of refractory metals, such as tungsten and molybdenum, are much *As defined in equations (5) and (6), Q and QG are normalized to the gas constant (or Boltzmann’s constant). Thus, the units of the two activation energies are K.

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Figure 1. Two examples of model predictions for the effects of tungsten particle size on green density, sintered density, and grain size

more sensitive to particle size than other metals. The properties of ceramics are even more sensitive to particle size since they cannot be pressed to high green densities due to their high hardness and brittle nature. PROPERTY MAPS Properties are governed primarily by grain size and sintered density. Here, the properties of nanograined materials are predicted by extrapolating conventional models to the nanoscale. Nanoscale powders may provide unique but unknown benefits that are not predicted by these models. For example, while hardness is predicted to increase with decreasing grain size, fracture toughness usually decreases, but nanograined materials may provide some unique combinations of hardness and toughness. The conventional models establish baseline properties expected of nanoscale powders and a means of quantifying any unpredicted property improvements found in future experimental work. Elastic Modulus The elastic modulus is calculated from:6 E = E0ρs3.4

W = W0 exp (-βH)

where W is wear loss measured in cm3, H is the hardness in kg/mm2, and values for the parameters W0 and β are 28 cm3 and 0.00418 kg/mm2, respectively. Fracture Strength Like hardness, fracture strength follows a Hall–Petch dependence on grain size. For metals the “best fit” model for room-temperature strength σ (in MPa) is:1,2 σ = 3Hσs5

(10)

where H is the hardness in kg/mm2 and σs is the fractional sintered density. For ceramics, the following equation was used: σ = ρs

(7)

(9)

(

θ σ0 + —— G

)

(11)

where ρS is the fractional sintered density and E0 is the elastic modulus of the pore-free material.

where σ0 is the fracture strength of the pore-free material, θ is a material constant, and G is the grain size in µm.

Hardness/Abrasion Resistance Room-temperature hardness follows the Hall– Petch relation 7 and can be predicted from the relation:

Ductility/Fracture Toughness The ductility of sintered metals depends primarily on their densities and can be expressed by the empirical equation:6

H = ρs

(

θ H0 + —— G

)

(8)

where ρS is the fractional sintered density, H0 is the

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hardness of the annealed pore-free material, θ is a material constant, and G is the grain size in µm. The abrasive-wear loss of hard materials is linked to hardness and can be estimated from the relation:1,2

ε0ρs3/2 εmax = ———————— 1+160 (1-ρs)2

(12)

where ρS is the fractional sintered density and ε0 Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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is the ductility of the pore-free material. This same relation is used for ceramics but with fracture toughness in place of ductility. Electrical Resistivity Electrical resistivity R increases with porosity and generally follows the structure-independent semi-empirical relationship obtained by Koh and Fortini:8 1+11(1-ρs)2 R = R0 —————— ρs

(13)

where ρs is the fractional sintered density and R0 is the electrical resistivity of the pore-free material. Thermal Conductivity The thermal conductivity λ of metals can be calculated from the electrical resistivity R using the Wiedemann–Franz relationship:9 LT λ = —— R

(14)

where L is the Lorenz number and T is the absolute temperature in K. For ceramics, thermal

conductivity can be calculated directly from the Koh and Fortini relationship: ρs λ = λ0 —————— 1+11(1-ρs)2

(15)

where λ0 is the thermal conductivity of the porefree material. Baseline properties of pore-free materials are summarized in Tables I and II. The values are based on material properties given by the CES Selector Version 4.5 software (Granta Design Limited). As examples of the property model predictions, the properties of tungsten are plotted in Figure 2 as functions of particle size for the two cases shown in Figure 1. For tungsten powder pressed at 250 MPa and sintered at 2,000°C, the properties follow density and peak at approximately 1 to 3 µm. Higher strengths and hardnesses are possible with nanoscale powders and ultrahigh compaction pressures. Property maps can be constructed by plotting the properties as functions of each other. Utilizing this method, it is possible to identify unique property combinations. Plots of modulus, hardness, ductility,

TABLE I. BASELINE METAL PROPERTIES Metal Q (K) QG (K) K (µm/s1/3) E0 (GPa) H0 (VHN) Θ (VHN⋅µm1/2) ε0 (%) R0 (µΩ⋅m) L (10-8 W⋅Ω/K2)

W

Fe

Cu

Ni

Ti

Mo

Re

Ta

Nb

Al

3,652 11,430 23.5 400 250 110 15 0.053 3.04

2,000 7,000 23.5 204 75 110 35 0.097 2.47

1,800 5,000 23.5 145 50 110 50 0.017 2.28

2,000 7,000 23.5 214 80 110 50 0.068 2.2

2,200 8,000 23.5 116 120 110 25 0.42 3.15

3,200 10,000 23.5 325 150 110 30 0.054 2.61

3,500 11,000 23.5 470 260 110 25 0.19 2.98

3,100 11,000 23.5 186 50 110 50 0.125 2.47

2,800 10,000 23.5 105 80 110 50 0.14 2.68

1,100 4,000 23.5 70 25 80 40 0.027 2.2

TABLE II. BASELINE CERAMIC PROPERTIES Ceramic Q (K) Q G (K) K (µm/s1/3) E0 (GPa) H0 (VHN) Θ (VHN⋅µm1/2) σ0 (MPa) ε0 (MPa⋅m1/2) R0 (µΩ⋅cm) λ0 (W/(µ⋅K))

Al2O3

Cr2O3

TiC

WC

SiC

B4C

MoSi2

TiN

2,500 11,430 23.5 1,200 400 400 200 4 1.0⋅1022 38

2,500 11,430 23.5 100 250 100 200 4 1.0⋅1022 30

2,500 11,430 23.5 435 3,000 200 400 2.5 2.0⋅102 25

2,500 11,430 23.5 680 2,500 100 700 3 1.0⋅102 80

2,500 11,430 23.5 400 2,600 100 350 4 1.0⋅1010 100

2,500 11,430 23.5 450 4,400 100 550 4 1.0⋅108 40

2,500 11,430 23.5 440 1,200 100 200 2 1.5⋅101 30

2,500 11,430 23.5 435 2,500 200 400 2.5 2.0⋅102 20

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Figure 2. Two examples of model predictions for the effect of tungsten particle size on various properties

Figure 3. Property maps for metals of modulus, hardness, wear resistance, ductility, electrical resistivity, and thermal conductivity as functions of strength

electrical resistivity, thermal conductivity, and wear resistance as functions of strength are given in Figure 3 for ten different metals. Most properties either correlate or inversely correlate with each

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other. For example, modulus, hardness, and abrasion resistance correlate directly with strength, while ductility is inversely related. Interesting combinations can be identified for electrical resistivity or Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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Figure 4. Property maps for ceramics of modulus, hardness, wear resistance, fracture toughness, electrical resistivity, and thermal conductivity as functions of strength

thermal conductivity and strength. Lower-strength copper and aluminum tend to be the best electrical and thermal conductors. The unique combination of high strength and high conductivity of tungsten is evident from Figure 3. Plots of modulus, hardness, fracture toughness, electrical conductivity, thermal conductivity, and wear resistance as functions of strength are given in Figure 4 for eight different ceramics. The properties of ceramics show similar correlations with each other as metals. In general, ceramics provide high modulus, high hardness, good wear resistance, and a wide range of electrical and thermal conductivities, but poor fracture toughness. The high strength of tungsten carbide sets it apart from the other ceramics. COST-NORMALIZED PROPERTY MAPS The range of properties of the different materials shown in Figures 3 and 4 results from the range of sintered densities achieved of the different particle sizes. While some applications require maximum values for certain properties and will pay a premium for them, the most common applications will only pay for materials that provide the optimal price/performance value. As a first estimate of the value for nanoscale powders, the preVolume 44, Issue 1, 2008 International Journal of Powder Metallurgy

dicted properties can be divided by the powder prices to normalize them. The cost of powders over a wide range of particle sizes was analyzed. Differences in impurity levels can have a large effect on powder costs. Powder costs also vary due to fluctuations in material prices, especially metal prices (in recent years), but in general they follow a power law relationship with particle size. Plots are shown in Figure 5 for metals and ceramics. This is mostly related to the greater cost of creating higher surface area. Some exceptions exist if a low-cost chemical process route is feasible. For example, coarse tungsten powder (>10 µm) is not lower in cost than 1 µm powder and can even be more expensive because of longer processing times or additives to grow the particles. The cost of refractory metal powders produced via chemical processes generally does not decrease as the particle size increases above a few micrometers. In contrast, metals such as copper, iron, and titanium continue to decrease in cost until they approach the cost of wrought metal. On the other end, making nanoscale powders generally requires alternative techniques such as gas-phase synthesis or exploding wires and these processes are generally much more costly. Some of the cost

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Figure 5. Power law relationships between powder cost and particle size: (a) metals and (b) ceramics

Figure 6. Cost-normalized properties of tungsten. Pressures and temperatures refer to compaction and sintering parameters

is related to the lower volumes of powder produced and the inefficiencies of new processes, but nanoscale powders are unlikely to match the cost of conventional powders. Dividing the predicted properties by the powder cost enables plotting of cost-normalized properties. Examples are shown for tungsten in Figure 6 for the two cases given in Figure 2. For powders pressed at 250 MPa and sintered at 2,000°C, peak values occur at ~1 µm for strength, ductility, and thermal conductivity, indicating the optimal value proposition. As the particle size decreases below 1

50

µm, their value drops. This finding is in agreement with the current market structure in which the most commonly used powders have particles sizes of 0.8 µm to 3 µm. The higher strength and hardness levels possible with nanoscale powders compacted at ultrahigh pressures are offset by the higher powder cost. For tungsten nanoscale powders to be economically useful on a large scale, they will need to be produced at lower cost, or provide a much larger improvement in property performance than is predicted from the models used in this study. Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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Figure 7. Cost-normalized properties of iron. Pressures and temperatures refer to compaction and sintering parameters

As another example, the cost-normalized properties of iron are shown in Figure 7. Unlike tungsten, no peaks are seen, thus coarse powders provide the best value proposition. Even property improvements with ultrahigh compaction pres-

sures provide a negligible incremental value in comparison to a coarser particle size. This simple economic analysis shows why conventional pressand-sinter ferrous PM uses coarse powders and exposes the hurdles that nanoscale powders must

Figure 8. Maps of cost-normalized properties versus cost-normalized strength for metals

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Figure 9. Maps of cost-normalized properties versus cost-normalized strength for ceramics

overcome to provide superior value. As with the absolute properties, cost-normalized property maps can be produced by plotting the cost-normalized properties as functions of each other. The plots in Figure 8 show the highstrength-per-cost ratio of iron and why it is so widely used for structural applications. The value of copper for thermal conductivity is also obvious. From the plots in Figure 9 for ceramics, tungsten carbide and alumina provide the optimal value for high-volume, cost-sensitive applications. Other metals and ceramics have niche applications only where high absolute performance is required at premium cost. COST MODELS Powder costs are only a portion of the cost of producing PM parts. Compaction and sintering costs must also be considered. The use of ultrahigh compaction pressures to consolidate nanoscale powders requires large presses with high tonnage, which results in high compaction costs. The low apparent density of nanoscale powders also results in a long stroke, which slows down production rates. Nanoscale powders have the potential to sinter at lower-than-conventional temperatures, reducing energy consumption and possibly allowing for lower-cost furnace construc-

52

tion. To fully analyze the costs of processing nanoscale powders, a cost model was constructed based on the approach developed by German10–13 for powder injection molding (PIM). German’s cost model for PIM was modified for die compaction. The model contains over 150 variables, so realistic assumptions were made in relation to overhead costs such as rent, maintenance, interest rate, facility use, electric rate, depreciation, and load balance. Ranges for these variables were evaluated where appropriate. Input values for the various models were obtained from current databases and supplemented, as needed, from external sources. Each unit operation was independently audited for costing rates and sensitivity analyses were conducted to determine the most significant factors. The part geometry is a key attribute that affects cost in several ways. To illustrate the cost model concepts, a ring geometry with a 2.54 mm OD, 1.27 mm ID, and a height of 0.85 mm was assumed. Compaction costs are calculated as a function of material, particle size, compaction pressure, and part size. A press was selected from a database of six presses, based on the tonnage required to achieve desired pressures. The hourly operating cost was calculated based on the capital cost, floor space, utility costs, maintenance costs, Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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and labor costs. The cycle time was calculated based on the stroke rate and the stroke distance, which depends on the apparent density of the powder and the compaction pressure. The green density was calculated as an output variable for input into the sintering cost model. A plot of compaction cost as a function of particle size for different compaction pressures for the ring geometry is shown in Figure 10. This plot is not material specific, but the resulting green density for a given combination of particle size and compaction pressure depends on material hardness. The compaction cost is dependent on particle size only at ultrahigh pressures. Ultrahigh pressures provide little benefit for ceramics, which cannot be pressed to high densities due to their lack of ductility. The cost of compaction of metals and ceramics is small compared to the raw material cost.

Figure 10. Effect of particle size and compaction pressure on compaction cost

Figure 11. Effect of particle size and material on sintered part cost

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Sintering costs were calculated based on the sintering temperature required to achieve a density of 96% of the pore-free level. The sintering temperature depends on material, particle size, and green density. A furnace was selected from a database of nine furnaces, based on the required sintering temperature. Sintering costs were normalized per unit volume and the number of ring parts that could be sintered per unit volume was calculated. The hourly operating cost was calculated from the capital cost, floor space, utility costs, maintenance, and labor costs. A 12 h sintering cycle was assumed. The sintering temperature required to achieve full density increases with coarser powders and lower compaction pressures. Sintering costs drastically increase at particle sizes which cannot be sintered in conventional furnaces. In some cases, a lower green density requires slightly smaller particle sizes to enable the use of conventional furnaces. The effect of particle size on sintered part cost for various metals is shown in Figure 11. Powder costs dominate sintered part costs. Lower sintering temperatures due to finer powders do not offset higher powder costs except in special cases. CONCLUSIONS Powder costs generally follow a power law relationship with particle size. Ultrahigh pressure compaction and low-temperature sintering of nanoscale powders provide a means of producing refined microstructures that result in improved hardness and strength. Ultrahigh compaction pressures are more costly than conventional pressures, but the compaction cost is small relative to powder cost. A reduction in sintering cost due to lower sintering temperatures of nanoscale powders does not offset their higher powder cost. Analysis of the value proposition of nanoscale powders by cost normalizing their properties shows that the incremental improvement they provide in performance does not compensate for their higher cost. For nanoscale powders to be useful for press-and-sinter PM, they will need to be produced at much lower cost, or provide a much larger improvement in property performance than predicted by conventional models. ACKNOWLEDGEMENTS The author gratefully acknowledges Randall M. German for sharing his spreadsheet models and

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Harald Lemke for insightful discussions and guidance on the economic analysis. REFERENCES 1. R.M. German and E. Olevsky, “Mapping the Compaction and Sintering Response of Tungsten-Based Materials into the Nanoscale Size Range”, Int. J. of Refract. Met. Hard Mater., 2005, vol. 23, pp. 294–300. 2. R.M. German and E. Olevsky, “Strength Predictions for Bulk Structures Fabricated from Nanoscale Tungsten Powders”, Int. J. of Refract. Met. Hard Mater., 2005, vol. 23, pp. 77–84. 3. R.M. German, Particle Packing Characteristics, 1989, Metal Powder Industries Federation, Princeton, NJ. 4. H. Su and D.L. Johnson, “Master Sintering Curve: A Practical Approach to Sintering”, J. Am. Ceram. Soc., 1996, vol. 79, pp. 3,211–3,217. 5. R.M. German, Sintering Theory and Practice, 1996, John Wiley and Sons, New York. 6. R.M. German, Powder Metallurgy and Particulate Materials Processing, 2005, Metal Powder Industries Federation, Princeton, NJ. 7. V. Richter and M.V. Ruthendorf, “On Hardness and Tough-

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8. 9. 10.

11.

12.

13.

ness of Ultrafine and Nanocrystalline Hard Materials”, Int. J. Refract. Met. Hard Mater., 1999, vol. 17, pp. 141–152. J.C.Y. Koh and A. Fortini, Inter. J. Heat Mass Transfer, 1973, vol. 16, pp. 2,013–2,021. J.E. Parrot and A.D. Stuckes, Thermal Conductivity of Solids, 1975, Pion, London. R.M. German, “The Impact of Economic Batch Size on the Cost of Powder Injection Molded (PIM) Products”, Advances in Powder Metallurgy and Particulate Materials— 2003, edited by R. Lawcock and M. Wright, Metal Powder Industries Federation, Princeton, NJ, 2003, part 8, pp. 146–159. R.M. Ger man, “Engineering Economics of Powder Injection Molding Component Production: Part II, Feedstock Costs”, P/M Science and Technology Briefs, 2003, vol. 5, no. 3, pp. 11–16. R.M. Ger man, “Engineering Economics of Powder Injection Molding Component Production: Part III, Production Costs”, P/M Science and Technology Briefs, 2003, vol. 5, no. 4, pp. 14–22 R.M. Ger man, “Engineering Economics of Powder Injection Molding Component Production: Part IV, Price Sensitivity”, P/M Science and Technology Briefs, 2004, vol. 6, no. 1, pp. 5–10. ijpm

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OUTSTANDING TECHNICAL PAPER: POWDERMET2007

CLOSE-COUPLED GAS ATOMIZATION: HIGH-FRAME-RATE ANALYSIS OF SPRAYCONE GEOMETRY Andrew M. Mullis*, Nicholas J. E. Adkins**, Zabeada Aslam***, I. McCarthy**** and Robert F. Cochrane*****

INTRODUCTION Close-coupled gas atomization is a technique widely used for the production of fine metal powders by the disruption of a molten metal stream via impinging high-pressure gas jets. Despite the widespread commercial utilization of this technique the mechanisms leading to break-up of the melt stream are not well understood. This is due to the complex nature of the physical interaction between the gas jets and the melt stream, and the commercial sensitivity intrinsic to proprietary atomizer die and nozzle designs. This has led to little detailed consideration of this process in the open scientific literature, although a number of semi-empirical relationships between median particle size and various atomization-process parameters have been proposed.1,2 Melt-flow rate, gas-flow rate and die pressure are all known to affect particle size, although probably the most useful combination of these parameters is the gas:metal (mass) ratio, GMR. Models have been proposed which relate median particle size to GMR, the most widely quoted of which is that due to Lubanska,3 which correlates particle size with (1 + GMR)1/2. For many potential powder metallurgy (PM) applications, both a small median particle size and a narrow size distribution in the product are desirable. While considerable progress has been reported on improving the efficiency with which the impinging gas jets disrupt the melt stream, hence reducing the mean particle size,4,5 most atomizer designs produce a distribution of powder sizes which span one order of magnitude or more.5 During normal operation of the close-coupled gas atomizer an irregular pulsation in the spray cone can often be observed at frequencies suffi-

The geometry of the spray cone during atomization of Ni31.5Al68.5 in a closecoupled gas atomizer operating with a generic die and nozzle design has been studied utilizing high-speed digital video techniques. Details of the region extending 5 cm from the spray nozzle at frame rates of up to 18,000 frames/s were recorded. The material was sprayed at a temperature ~1,830 K (corresponding to a superheat ~200 K), wherein sufficient thermal radiation was emitted for images to be recorded without any additional lighting. In order to quantitatively analyze the large number of still frames that result (up to 65,536), image processing routines capable of automating this process have been developed and used to measure the optical brightness and the position of the optical-intensity maximum of the material passing though a narrow window at a fixed distance from the nozzle tip. The results of this analysis show that the spray cone consists of a jet that precesses around the center axis of the atomizer in a regular manner at a frequency ~360 Hz. In order to understand the origin of this motion, further experiments were conducted with a laboratory-scale analogue atomizer which atomizes a water jet. It was found that the frequency of precession is essentially independent of the atomizing-gas pressure, but does depend upon the geometry of both the die and nozzle.

The award for this technical paper will be presented at the 2008 World Congress on Powder Metallurgy & Particulate Materials in Washington, D.C. *Reader in Solidification Processing, ***Research Fellow, ****Research Student, *****Senior Lecturer, University of Leeds, Institute for Materials Research, Clarendon Road, Leeds, LS2 9JT UK; E-mail: [email protected], **Technology Manager, CERAM Research, Queens Road, Penkhull, Stoke-on-Trent ST4 7LQ UK

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ciently low to be detectable by the human eye, a phenomenon reported in the literature6 and observable during our atomization experiments. This is attributed to fluctuations in the aspiration pressure that result from the impinging gas jets. Specifically, it has been suggested that it may be related to an oscillation between an open and closed wake downstream of the focus of the gas jets.6,7 Recently, significant progress has been made towards understanding close-coupled gas atomization utilizing high-speed imaging techniques.6,8 These have proved to be particularly fruitful when combined with Fourier analysis of the resulting images.6 In particular, it has been reported that, in addition to the low-frequency pulsing of the melt, a much higher-frequency oscillation6 or precession9 of the jet is also observed. It has been suggested that this may be a direct consequence of irregular wetting of the melt-delivery nozzle, producing a filament of melt that rotates around the tip of the nozzle in a regular manner.10 If precession is indeed due to the presence of an irregular rotating filament, this would suggest that instantaneously the metal sees only a small fraction of the available gas jets, thereby dramatically decreasing the GMR and potentially reducing the efficiency of the atomization process. As such, an understanding of the physical processes leading to this effect is important in order to optimize the spray atomization process, In this study, we describe high-speed digital imaging experiments performed during the atomization of Ni31.5Al68.5 (Ni-50 w/o Al, an industrial catalyst, hereafter referred to as Raney-nickel), and the subsequent Fourier analysis of the image sequences. These were then compared with images produced in a laboratory-scale analogue atomizer that atomizes a water jet. METAL ATOMIZATION AND IMAGING METHODS Atomization experiments were conducted at CERAM Research on 6 kg batches of Raney-nickel. A simple model die of the discreet jet type with 18 cylindrical jets arranged around a tapered meltdelivery nozzle at an apex angle of 45° was used in these experiments. The design, shown schematically in Figure 1, is similar to the USAG11 and Ames HPGA-I4 designs that have been widely discussed in the literature. Although this design is known to be inefficient in atomizing the melt stream, as the cylindrical jets produce choked flow and limit the velocity of the gas jets to Mach 1, we have chosen

56

to use this geometry for this experimental study for a number of reasons. Firstly, the simple jet geometry means that the gas flow is amenable to relatively straightforward numerical modeling. Secondly, unlike the convergent–divergent jets used to produce supersonic gas flow, the simple cylindrical jet can be operated over a wide range of pressures allowing us to investigate characteristics of the atomization process as a function of pressure. The melt was superheated by 200 K, giving a melt temperature prior to ejection of 1,813 K. At this temperature the melt stream is sufficiently bright that filming can take place using the radiant light from the melt, even at high frame rates. Consequently, no external light sources were used. The melt was ejected from the guide tube under a constant overpressure of 40,000 Pa, while the gas-jet pressure was maintained at a constant pressure of 3.5 MPa with pure argon. These operating conditions gave a melt-flow rate of 15.75 × 10 -3 kg s -1 and a gas-flow rate of 48.65 × 10-3 kg s-1 at a GMR of 0.324. Imaging of the melt spray cone was performed using a Kodak Ektapro 4540mx high-speed digital motion analyzer, operating at a frame rate of 18,000 frames/s. The motion analyzer was fitted with high-magnification optics which allowed full frame images (covering a distance ~5 cm from the die) to be imaged at a working distance of 25 cm. Each frame was 256 ¥ 64 pixels in size, with an eight-bit grayscale depth per pixel. Frames were stored separately as high-quality TIFF images without interlacing in 1 Gb of fast memory, giving a total storage of 64,000 frames, which corresponded to a total recording time of 3.64 s. A typical sequence of five consecutive frames from the imaging is shown in Figure 2. Here, because the imaging is performed using radiant light from the hot melt, the spray cone appears light

Figure 1. Close-coupled atomization die and nozzle—schematic

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Figure 2. Sequence of images of the atomization of Raney-nickel. Each frame is separated by 1/18,000 s

against a dark background. It is apparent from the images that the spray cone is highly inhomogeneous, with a number of bright regions (corresponding to a higher density of melt droplets) that can be tracked moving downwards from frame to frame. On the assumption that the droplets which comprise these bright agglomerations are co-moving with the feature itself, it is possible to estimate the vertical component of the velocity of the melt spray. Depending upon the particular feature selected, there was considerable variability in velocity, with calculated values ranging up to 30 m s-1. It is also apparent that there are considerable fluctuations in the amount of material instantaneously being delivered from the nozzle, particularly when a number of images are combined into a movie. Moreover, these fluctuations vary over a range of timescales, an observation that has been made a number of times previously.6,7 We have also observed in our experiments that the position of the center of the plume appears to oscillate around the vertical projection of the spray nozzle in a regular manner. However, it is not possible to determine by eye from the images whether this apparent oscillation is indeed a lateral oscillation of the jet position or a rotation of the jet. In order to analyze these fluctuations quantitatively we have performed a Fourier analysis on each of the 64,000 frames in order to build up a time sequence describing the history of these fluctuations over the time filming interval. FOURIER IMAGE ANALYSIS METHODS Fourier analysis of images resulting from highspeed filming of spray atomization has been Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

undertaken previously by Ting et al.,6 in which their images were divided into 10 equally sized rectangular regions. A two-dimensional Fourier transform was then performed on the resulting regions of the image. Here we have adopted a somewhat different approach aimed at quantifying the fluctuations in the amount of material being instantaneously atomized, and the position of the center of the spray cone. The method adopted here is designed to analyze the distribution of material passing through a narrow window oriented normal to the spray direction. We start by defining a window four pixels high which spans the entire 64 pixel width of the image, positioned at an arbitrary height, h, from the spray nozzle, as shown schematically in Figure 3. The grayscale intensity in each group of four pixels is averaged to create an intensity distribution plot of the material passing through the window in each frame. From this we calculate two statistics. The first is the mean intensity level, (-I), for the material passing through the window, which is given by: - = —— 1 I 64

64

ΣI

j=1

j

(1)

where j is an index that uniquely defines each of the 64 pixels in the width of the image and Ij is the intensity for that location obtained from the intensity distribution plot. The second statistic we calculate is: 64

Σ

Ij × j j=1 - = ———— j 64

ΣI

j=1

(2)

j

which corresponds to the center location of the

Figure 3. Fourier analysis procedure used to analyze high-speed video images— schematic

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spray cone, calculated from a weighted average of all the intensities in the image. For a symmetrical spray cone in which the center of the spray is vertically below the nozzle, this procedure gives a value for -j of 32. Both statistics, I and -j, have been calculated for the entire 3.64 s of filming using an automated batch image processing system programmed in MATLAB,12 giving two time sequences each of which is 65,536 elements long. In addition, each time sequence has been subjected to Fourier analysis. RESULTS: METAL ATOMIZATION EXPERIMENTS An overview of the time sequence for the mean intensity is shown in Figure 4(a). This shows that there is a high-frequency oscillation, which on this scale is not resolved, superimposed upon a

much lower frequency variation. The high-frequency oscillation is shown on an expanded scale in Figure 4(b), although this sequence covers only 0.05 s of filming. In addition, on Figure 4(b), individual mean intensities from consecutive frames are shown in order to demonstrate that the highfrequency oscillation is unrelated to the frame rate at which the camera is operating. Figures 5(a) and 5(b) show the equivalent time sequence for the weighted mean center position, -j. This shows a similar high-frequency oscillation (again not resolved in Figure 5(a)), although in this case there is little evidence of the low-frequency variation evident in the I data. The Fast Fourier Transforms (FFTs) of the time sequences for -I and - are given in Figures 6(a) and 6(b). Both show a j high spectral power with a sharp peak in the

Figure 4. Time-series of gray level intensity (a) over entire 3.64 s of a filming run and (b) in more detail over 0.05 s showing that the oscillation is unrelated to the camera frame rate

Figure 5. Time-series of melt center position (a) over entire 3.64 s of filming run, (b) in more detail over 0.05 s showing that the oscillation is unrelated to the camera frame rate

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Figure 6. Fourier spectra of time-series corresponding to (a) gray level intensity and (b) position of center of jet

vacinity of a frequency ~360 Hz, which in the case of -j corresponds to the regular oscillation of the spray about the vertical direction. The other feature noted regarding the FFT analysis is that I has considerable spectral power at low frequencies which is not apparent in the sequence for -j, which corresponds to the irregular pulsing in the amount of material at the die nozzle previously reported. This low-frequency spectral power is shown in more detail in Figure 7; it is evident that the main power occurs at frequencies of 2.2 Hz, 2.7 Hz, 4.1 Hz, 5.5 Hz, 8.8 Hz, and 15.1 Hz, although numerous other frequencies are also present suggesting that the oscillation may be chaotic. With regard to the apparent oscillation of the spray about the vertical position, it is not possible to determine whether this is due to a lateral oscillation in the jet position or a rotation of the jet by eye. However, because the frequency of the oscil-

Figure 7. Fourier analysis of recorded intensity from spray atomization, showing low-frequency components of the oscillation

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

lation is mirrored in the intensity, we believe that we are observing a steady rotation of the jet around the vertical direction, as previously reported by Anderson.10 Periods of high intensity in the radiant light are attributed to the jet being directed towards the viewing window in the atomizer (along the viewing angle), while periods of low intensity correspond to the jet being directed away from the viewing window (180° from the viewing angle). Moreover, if this model is correct we would expect the time sequences for I and -j to be shifted in phase relative to each other, with the peaks and troughs in -j occuring at 90° and 270° from the viewing angle, Figure 8.

Figure 8. Model for precession of atomization jet, giving the observed anti-phase correlation in gray-level intensity and jet-center position time series—schematic

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Figure 9. Spray cone showing how a precessing jet could lead to intensity and position maxima 90° out of phase—schematic

As shown in Figure 9, this does indeed appear to be the case, confirming that the spray is a jet that precesses around the surface of a narrow cone at a near regular angular velocity of 360 rps. Similar high-frequency oscilations in the jet position have been observed during the atomization of 304 stainless steel.7 ANALOGUE ATOMIZATION EXPERIMENTS In order to further understand the features observed during the atomization of Raney-nickel, we have commissioned an analogue atomizer whereby we can atomize a water stream using the same die and nozzle design as that used for metal atomization. The design of the analogue atomizer

Figure 10. Analogue atomizer—schematic

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is shown schematically in Figure 10. Four to six standard bottles of compressed air were connected together using armored steel hose, which fed a single, high-pressure regulator capable of delivering a minimum of 4.0 MPa pressure on the outlet side at a flow rate of up to 4 kg min-1. This was delivered (via an electronic switching valve), to the plenum chamber of the die. Water, at an over pressure of ª40,000 Pa was delivered to the nozzle via a pumped header tank. The die and nozzle arrangement is housed within a Perspex cubicle which served to contain the water mist produced during atomization. Illumination was provided by two high-power halogen lamps mounted in the base of the unit. The top region of the enclosure was blacked out with the exception of a camera viewing port to provide contrast in the high-speed video images. The die-and-nozzle arrangement was mounted at the top of the enclosure. During atomization of Raney-nickel, the melt delivery nozzles were enclosed in hot-pressed boron nitride in order to resist the highly aggressive metal. With no such requirement during the analogue atomization experiments on water, we used either brass or, in some instances, Perspex which provides a transparent nozzle so the liquid flow can be observed. Figure 11 shows an early sequence of consecutive images taken of water atomization in the analogue atomizer, using the high-speed camera at a frame rate of 18,000 frames/s. Note that the liquid stream was illuminated in reflected light rather than radiant light, although by using a black enclosure the appearance was similar to liq-

Figure 11. Sequence of images of atomization of water. Each frame is separated by 1/18,000 s

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uid-metal atomization. The pressure used in this run was 2.0 MPa, as opposed to 35 MPa during atomization of Raney-nickel. Due to the lower density of water, the mass ratio of gas to atomized fluid is actually higher by a factor of 2.25. It is clear, even from the raw images, that in this case the fluid is non-wetting as it emerges directly from the 2 mm dia. aperture in the nozzle. Moreover, when subject to Fourier analysis the images reveal no precession and indeed very little pulsing of the material delivered to the nozzle tip. To determine whether this behavior, which is significantly different from the behavior of the Raney-nickel when atomized, was due to the nature of the fluid or to the reduced operating pressure, we subsequently added a powerful surfactant (sodium dodecyl sulphate) to the system’s water reservoir at a concentration of 0.1 g

Figure 12. Sequence of images of atomization of water with surfactant to aid tip wetting. Each frame is separated by 1/18,000 s

l-1. Figure 12 shows a sequence of consecutive frames from the high-speed camera resulting from this addition. All other parameters were held identical between the runs depicted in Figures 11 & 12. It is clear from these images that wetting of the nozzle tip was achieved. The corresponding Fourier analysis of the timeseries data from the entire image sequence is shown in Figures 13(a) and 13(b). Note also that in this and all the Fourier analyses of the analogue atomizer there is an artifact at 100 Hz, which is due to flicker in the illumination at a frequency of 2 x UK mains AC. Although some differences can be observed between these traces and the traces for Raney-nickel atomization, notably that the peak spectral power is (a) moved to a higher frequency and (b) is more diffuse, it is clear that there is now definite evidence of both precession and low-frequency pulsing. Consequently we may conclude that precession of the spray jet appears to be a direct consequence of the wetting of the nozzle tip. In the absence of wetting, a steady vertical jet breaking up into droplets is observed. Having demonstrated that the precession of the spray cone can be recreated in the analogue atomizer, we have attempted to understand the factors that influence the observed precessional motion. Our first series of experiments was designed to elucidate the dependence of the observed frequency of rotation on the gas pressure used for atomization. To this end, high-speed video was taken of the analogue atomizer running at pressures from 0.5 MPa to 4.0 MPa at intervals of 0.25 MPa. Two of the resulting Fourier analyses characteris-

Figure 13. Fourier spectra of time-series corresponding to (a) gray-level intensity and (b) position of center of jet, for water atomized with surfactant

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Figure 14. Fourier spectra of time-series corresponding to melt-center position (a) 7.5 bar and (b) 20 bar, showing virtually no dependence of frequency of precession on operating pressure

tic of these experiments are shown in Figure 14(a) and 14(b). The two frequency spectra are virtually identical and, indeed, over the pressure range considered, we believe that to within experimental error there is no variation of precessional frequency with atomization gas pressure. One variable that we have identified that does appear to have an effect on the nature of the precession is the engineering tolerance applied during the die-manufacturing process. Two dies were manufactured to the same engineering drawings. In one, the holes were produced by conventional drilling, and in the other by spark erosion. Although notionally identical, the method of producing the holes, which are close to the minimum diameter that can be produced by conventional drilling, appears to make a significant difference

in the resulting flow dynamics. In particular, for drilled holes we note a considerable eccentricity on some of the holes (e = 0.92 is typical, corresponding to a variation in the hole diameter of 40 mm) whereas for the spark eroded holes this figure was significantly closer to 1 (e = 0.97), which presumably, in part, reflects the fact that no torque is imparted to the work piece during cutting. Figure 15(a) and 15(b) show the Fourier spectra resulting from high-speed imaging experiments on the analogue atomizer using these two dies, with all other parameters held constant. The atomizing-gas pressure in both cases was 4.0 MPa. The die produced by spark erosion produced spectra with (a) a much more tightly focused peak at around 1,000 Hz than the die produced by drilling, and (b) the low-frequency components,

Figure 15. Fourier spectra of time-series corresponding to gray-level intensity for dies fabricated by (a) drilling and (b) spark erosion

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Figure 16. Geometry of the four melt nozzles investigated. Dimensions in mm

although still present, were confined to a smaller frequency range. Finally, we have investigated the extent to which the actual geometry of the nozzle affects the observed precession of the spray jet. In addition to the original nozzle design with a flat tip we have also examined three other geometries, which are depicted in Figure 16. The nozzle designated Type 1 is the original design with a flat annular ring 1.45 mm wide at the tip and a straight guide tube to deliver the melt to the tip. Type 2 flares the guide tube at an angle of 30°, but retains a flat section at a reduced width of 0.7 mm. Type 3 also flares the guide tube at 30° but brings this to a sharp edge at the circumference of the nozzle, eliminating the flat tip entirely. Type 4 is similar to Type 3 and eliminates the flat tip but flares the guide tube on a hemispherical radius of 2.5 mm. The Fourier spec-

Figure 17. Fourier spectra in gray level corresponding to atomization with different nozzle geometries: (a) Type 1, (b) Type 2, (c) Type 3, and (d) Type 4

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tra in the gray-level intensity resulting from highspeed filming of atomization experiments at 4.0 MPa, under otherwise identical conditions, are shown in Figures 17(a) through 17(d). Clear dif ferences in the spectra can be observed, with the Type 1 nozzle giving the most diffuse high-frequency peak and the Type 4 nozzle the sharpest high-frequency peak. In terms of the width of the peak, Type 2 & 3 nozzles performed in a similar manner, although the peak was shifted to higher frequencies for the Type 3 nozzle, which contains no flat area at the tip. In terms of powder production, it is difficult to draw definite conclusions regarding the quality of the resulting powders, although we can differentiate between these nozzles by their spectra. CONCLUSIONS The compexity of the close-coupled gas-atomization process is well documented and is apparent in the results presented here. Similar to other studies6 we have observed an irregular pulsing in the amount of material that is instantaneously delivered to the die nozzle, for which models have been proposed by T ing et al. 7 We have also observed that the spray cone consists of a jet that precesses with a regular angle around the surface of a narrow cone. This observation, although made elsewhere,6 has received relatively little attention. The origin of this precession is not yet fully understood. It is clear that the precession is a direct consequence of wetting of the melt-delivery nozzle, although the frequency appears to be independent of the atomization-gas pressure. Some characteristics of the precession, particularly its regularity (half-width of the primary frequency peak) and the presence of low-frequency components, appear to be related to the engineering tolerances associated with the die-manufacturing process, but this also appears to have little effect on the primary frequency of rotation. In contrast, the geometry of the melt-delivery nozzle appears to have a significant effect on both the regularity of the precession and its primary frequency.

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ACKNOWLEDGEMENTS This work was funded by the European Commission (contract number NMP-CT -2004500635) under the Sixth Framework Programme as part of the IMPRESS project “Intermetallic Materials Processing in Relation to Earth and Space Solidification,” coordinated by the European Space Agency. REFERENCES 1. D. Bradley, "Atomization of a Liquid by High-Velocity Gases: II", J. Phys. D: Appl. Phys., 1973, vol. 6, pp. 2,267–2,272. 2. A. Lawley, Atomization, The Production of Metal Powders, 1992, Metal Powder Industries Federation, Princeton, NJ. 3. H. Lubanska, "Correlation of Spray Ring Data for Gas Atomization of Liquid Metals", J. Metals, 1970, vol. 22, pp. 45–49. 4. I.E. Anderson, R.S. Figliola and H. Morton, "Flow Mechanisms in High-Pressure Gas Atomization", Mater. Sci. Eng. A, 1991, vol. 148, pp. 101–114. 5. I.E. Anderson and R.L. Terpstra, "Progress Toward Gas Atomization Processing with Increased Uniformity and Control", Mater. Sci. Eng. A, 2002, vol. 326, pp. 101–109. 6. J. T ing, J. Connor and S. Ridder, "High-Speed Cinematography of Gas-Metal Atomization", Mater. Sci. Eng. A, 2005, vol. 390, pp. 452–460. 7. J. Ting, M.W. Peretti and W.B. Eisen, "The Effect of WakeClosure Phenomenon on Gas Atomization Performance", Mater. Sci. Eng. A, 2002, vol. 326, pp. 110–121. 8. S.P. Mates and G.S. Settles, "A Study of Liquid Metal Atomization Using Close-Coupled Nozzles, Part 2: Atomization Behavior", Atomization and Sprays, 2005, vol. 15, pp. 41–59. 9. A.M. Mullis, N.J. Adkins, Z. Huang and R.F. Cochrane, "Quantitative High Frame Rate Analysis of the Spray Cone Geometry During Close-Coupled Gas Atomization ", Proc. 3rd International Conference on Spray Deposition & Melt Atomization, 2006, CD proc., University of Bremen, Bremen, Germany. 10. I.E. Anderson, R.L. Terpstra, J.A. Cronin and R.S. Figliola, "Advances in Powder Size Control and Ultrafine Powder Production by Gas Atomization", Oral presentation, ibid ref. no. 9. 11. V. Anand, A.J. Kaufman and N.J. Grant, Rapid Solidification Processing, Principles & Technologies II, edited by R. Mehrabian, B.H. Kear and M. Cohen, 1978, Claitor, Baton Rouge, LA, pp. 273–286. 12. MATLAB is a trademark of The MathWorks Inc. ijpm

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EQUIPMENT MANUFACTURERS ABBOTT FURNACE COMPANY www.abbottfurnace.com Abbott Furnace Company specializes in continuous furnace technology for sintering, steam treating, heat treating, annealing, tempering and brazing. Technical innovations include Ceramic Muffles and Belts, Advanced VariCool System, Quality Delube Process and Computerized Controls. Abbott also offers custom fabrication of replacement parts, a full line of spare parts and repair and calibration service. ABTEX CORPORATION www.abtex.com Abtex Corporation is a singlesource manufacturer for abrasive deburring brushes and the machines needed to apply them. Brush line additions include 6” and 8” O.D. composite hub radial wheels in ?”, ?” and 1” widths. Supplementing its end deburring machines, the deburring systems group now offers both wet and dry process planetary head flowthrough systems for flat parts, and rotary indexing systems for addressing more complex part geometries. ALLOY ENGINEERING COMPANY www.alloyengineering.com The Alloy Engineering Company has been recognized for the expertise in the design and fabrication of products utilized in high-temperature and corrosive environments since 1943. It has been our commitment to provide innovative, reliable, and costeffective solutions to our customers. When you are faced with a component need that involves high-temperature or corrosive environments, call the experts and put The Alloy Engineering Company to work for you!

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ANTER CORPORATION www.anter.com/PM Anter Corporation is a leading manufacturer of thermophysical properties-measuring instruments. Products specific to the powder metal industry include our Unitherm™ Model 1161V vertical dilatometer and our FlashLine™ 5000 laser flash for sintering studies to 1,600°C in air, inert or reducing atmospheres. Properties include thermal expansion (CTE), thermal conductivity, specific head capacity and thermal diffusivity. Contract lab services are also available. Representatives worldwide. ISO9001:2000 Certified. ARBURG GMBH + CO KG www.arburg.com ARBURG is one of the world’s leading manufacturers of injection molding machines with clamping forces from 125 to 5.000 kN. The product range is completed by robotic systems, complex projects and other peripherals. ARBURG holds a leading position in the PIM sector for decades. The PIM range includes ALLROUNDER injection molding machines, which are especially equipped for the processing of powder materials, a comprehensive customer support and training courses. BATTENFELD OF AMERICA, INC. Battenfeld—Ready to Meet Your Future! www.battenfeld-imt.com Innovation is an integral part of any corporate strategy. Creative thinking generates new ideas that flow into product development, producing machinery and equipment with top level performance. This has been Battenfeld’s philosophy since 1948, when this company built one of the first injection molding machines. Consistently driven by market demand for high-grade, reliable, user-friendly machinery and turnkey solutions.

Always in close partnership with our customers, who rely on our expert counseling in applications engineering and our fast, comprehensive service. Products/Services—Injection Molding Machines Hydraulic machines (25 to 1600 tons) Electric Machines (33 to 300 tons) Toggle machines (55 to 650 tons) Vertical Machines (44 to 270 tons) Micromolding (5 ton complete micromolding solution) Automation Complete Turnkey solutions BRONSON & BRATTON INC. www.brons.com We are designers and fabricators of PM Tooling Design: your part, your press, our finished design Engineering: our experience, our CAD, equals totally integrated tooling Technology: our computer database with design variations will conform to your equipment requirements Processing: our CAM system integrates the engineering and machine data required for quality tools Quality: has been a tradition at Bronson & Bratton since 1948. We are ISO 9001:2000 Certified CAD + CAM = CIT (Computer Integrated Tooling) CENTORR VACUUM INDUSTRIES INC. www.centorr.com CVI is a 50-year-old manufacturer of custom high-temperature vacuum and controlled-atmosphere heat-treat and sintering furnaces for the Metals and Ceramics industries. Applications include heat treating, brazing, sintering, hot pressing, diffusion bonding, and injection molding of metals or ceramics. Furnaces are available with either refractory metal or graphite hot zones in sizes from 1 cu. in. to several cu. meters, from 1,000°C to 3,000°C.

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CIECO, INC. www.ciecocontrols.com CIECO offers five levels of press controls for the powder metal industry. From low-cost PPC1100R to the Automator II controller. Our dual microprocessor controls eliminate the high cost of dual plc packages and comply with OSHA, ANSI and CSA safety standards. Visit our Web site at www.ciecocontrols.com to view these controls. For an Internet Webinar demonstration on the Automator II controller, call our customer service department at 412-262-5581. C.I. HAYES, A GASBARRE PRODUCTS COMPANY www.cihayes.com For the past 103 years, C.I. Hayes has manufactured industrial furnaces and generators for many industrial applications. The furnace line includes high-temperature pusher furnaces, singlechamber and continuous vacuum furnaces with air or oil quench capabilities, tube strip furnaces, and conventional continuous mesh belt furnaces for sintering, steam treating, delubing. Endothermic, exothermic, and dissociated ammonia generators are manufactured in various sizes. Custom-designed furnaces are manufactured for specific parts and processes. CLEVELAND VIBRATOR www.clevelandvibrator.com Web site presents complete line of ultrasonic lab equipment, air and electric-powered feeders, screeners, conveyors and tables for bulk material compaction and fine screening applications. Includes specifications, dimensional diagrams, and case histories. The Web site also presents Cleveland Vibrator's full line of air-piston, electric, electromagnetic and ball vibrators for promoting the flow of bulk material. Suggested applications, specifications, and complete pricing information and

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placement of orders are also available. CM FURNACES, INC. www.cmfurnaces.com Furnaces & Equipment: Furnaces operating at temperatures from 1,200°F to 4,000°F. Batch and continuous pusher furnaces from lab scales to fully automated production units. All electric with high-efficiency insulation packages. Atmospheres: Furnaces available to operate in hydrogen, nitrogen, inert or air atmospheres. Continuous dew point and oxygen-level monitoring and control are offered. Other Products/Services: In-line delube and debind ovens with air, inert and/or reducing atmospheres. Debind ovens for BASF binder system. Toll firing and process development. DORST AMERICA, INC. www.dorstamerica.com Dorst offers the highest precision compacting and calibrating presses available with excellent productivity and maximum energy efficiency—all with removable die sets. Options available include automatic dieset change, self programming and optimization for the most demanding applications. Also available are part handling automation, existing press remanufacturing, customized preventative maintenance programs, as well as operation, set-up, maintenance and tool design training. ELMCO ENGINEERING, INC. www.elmco-press.com ELMCO Engineering Inc. is a leading manufacturer of new and rebuilt PM equipment. We service all makes of presses, provide control and feeder upgrades, and have an extensive parts inventory at three locations. We offer our own new ELMCO multi-motion mechanical presses, and standard molding mechanical presses, hydraulic specialty presses, plus

inclined and upright mechanical sizing presses. As Yoshizuka’s North American representative, we offer a full line of compacting presses, including state-of-the-art CNC hydraulic servo models. ELNIK SYSTEMS, Div. of PVA MIMtech, LLC www.elnik.com 1) Manufacturer of "one-step debind-sintering furnaces" Model MIM 3000 for metal injection molded parts for any binder with any metal from aluminum to titanium. Elnik provides refractory (molybdenun/tungsten) metal furnaces and also graphite furnaces with laminar gas flow retorts. 2) Manufacturer of first-stage debinding systems such as catalytic, thermal and solvent debinding ovens for BASF Catamold feedstock, wax-feedstock and water-soluble feedstock. FETTE COMPACTING www.fetteamerica.com FETTE GmBH, the world leader in tablet press technology, also offers a range of high-precision hydraulic presses for the manufacturing of carbide cutting inserts. These systems can be provided complete with pick-andplace robots for off-loading and the touch-screen control system includes advanced data-acquisition capabilities. Advanced dataacquisition capabilities. GASBARRE PRODUCTS, INC. www.gasbarre.com Provides full-service design, manufacturing and marketing of capital equipment for the particulate materials and thermal processing industries. Featuring Gasbarre Mechanical Presses, Best Hydraulic Presses, PTX-Pentronix High Speed Presses and Part Loaders, SIMAC Isostatic Presses, Sinterite Furnaces, C.I. Hayes Furnaces, McKee Carbide Tooling and related services.

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Gasbarre supplies all processing equipment for the PM industry, from atmosphere generators to powder-handling equipment, presses, sintering & annealing furnaces, sizing presses and oilimpregnation equipment. H.W.F. INC. H.W.F. Inc.'s Powdered Metal Compacting Presses. Step up to rated press capacity. Capitalize on high production levels, lower maintenance time and quiet operation. Tonnage ranges from 1 ton to 800 tons. Presses are backed by H.W.F.'s 2-year warranty. HERNON MANUFACTURING INC. www.hernonmfg.com Since 1978, Hernon Manufacturing has produced high-performance impregnation resins and processing equipment. Hernon Impregnation Resin (HPS™) offers a breakthrough in sealing leaking porous metals such as powder metal castings and sintered metal parts. HPS™ also offers other benefits such as increased lubricity, which lowers tool wear, and resistance to degradation by hydrocarbon solvents such as gasoline, motor oil, and transmission fluid. Hernon Manufacturing provides complete impregnation systems including design and installation. HOLROYD EDGETEK www.holroyd.com For over a century Holroyd has been a builder of precision machine tools for the manufacturing of high-precision gears, worms, worm wheels and rotors. For the powdered metal industry Holroyd also produces the line of Edgetek Superabrasive Machining and Turning Systems. The Edgetek process has been effective for removing difficult-tomachine materials, interrupted cuts, and high metal-removal rates for powdered metals and sinter-hardened powdered metals. Additionally a substantial increase in tool life over convenVolume 44, Issue 1, 2008 International Journal of Powder Metallurgy

tional machining methods will result in lower cost per part. LITTLEFORD DAY, INC. www.littleford.com Manufacturer of processing equipment, including horizontal mixers (batch and continuous), granulators, agglomerators, vacuum dryers, conical mixers, sigma mixers, vertical high-intensity mixers, liquid dispersers, pressure reactors, sterilizers, and extractors. We also provide pilot plant and laboratory equipment and maintain a completely equipped test center to assist customers in process development and scale-up. In addition, Littleford Day maintains an extensive rental fleet so customers may run field trials at their facilities. MAGNAFLUX QUASAR www.magnaflux.com Quality Control Testing Equipment: Automated Nondestructive Test system to measure structural integrity of sintered powder metal components. The Quasar 4000 Process Compensated Resonant Testing (PCRT) System reduces the shipment of bad parts by using resonant vibrational frequency patterns to test production parts at line rates, predicting structural performance of parts that will fail due to unacceptable cracks, chips, and voids. Our technology also finds deviations in material mix, hardness, density, and dimensional differences. Manual or automated systems available. MAX-TEK, LLC SUPERABRASIVE MACHINE TECHNOLOGIES www.maxteckmachine.co, Max-Tek, LLC Superabrasive Machine Technologies provides superabrasive turning and grinding systems using plated CBN and Vitrified CBN grinding wheels. The Max-Tek approach is particularly effective in interrupted cutting of sprockets and peel grinding of

journals. Max-Tek, LLC can provide fully integrated systems including automation and inspection for high-volume powder metal and MIM applications. MINOX-ELCAN INC. www.minox-elcan.com Minox/Elcan works with customers to provide screening solutions for their products. The high-performance screening equipment offers significant advantages over vibratory and ultrasonic machines. These performance advantages are demonstrated on production-sized equipment in our full-scale testing/tolling facility in Mamaroneck, NY. OSTERWALDER, INC. www.osterwalder.com OSTERWALDER AG develops and manufactures state-of-the-art hydraulic and mechanicalhydraulic powder presses. The wide product range offers system solutions for pressing iron, ceramic, tungsten carbide powders and other materials to small precision parts or sophisticated structural parts of first-class quality. OSTERWALDER AG provides a user-oriented press technology exceeding today's requirements. SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures high-temperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as micro-porous kiln furniture. We are also a distributor for Ferro Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004.

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SMS MEER GMBH www.sms-meer.com SMS Meer GmbH is part of the SMS group and is located at Mönchengladbach, Germany. The hydraulic press division offers forging and powder compaction presses. We are over 50 years a competent partner for the metal powder, ceramics and tungsten carbide industry and have sold more than 1,800 pf powder presses. Range of powder presses and adapters: - Hydraulic CNC presses from 600 up to 20,000 kN - Hybrid CNC up to 2,500 kN - High-speed mechanical presses from 30 up to 450 kN - Controlled punch adapters (CPA) with up to eight integrated CNC press axes SURFACE COMBUSTION, INC. www.surfacecombustion.com Surface Combustion offers a diverse product offering for batch and continuous furnace designs for atmosphere, non-atmosphere, or vacuum processing of ferrous and/or nonferrous components/ materials. Surface also produces the industry's most popular endothermic and exothermic gas atmosphere generators. THE FURNACE BELT COMPANY LTD. www.furnacebeltco.com A Certified ISO 9001:2000, custom belting manufacturer specializing in high-temperature powder metal sintering applications. Round or flattened wire belt specifications include; balanced, double balanced, rod reinforced, compound and many others, in friction or chain-drive configurations. Industries served include; copper brazing, metals heat treating, food handling & processing, foundry, agriculture, mines, packaging & pharmaceuticals. Full range of flat wire belting. See us @ www.furnacebeltco.com

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THE MODAL SHOP, INC. www.ndt-ram.com The Modal Shop is a leader in the field of dynamic quality instrumentation offering industrial grade, resonant inspection nondestructive test systems for the powder metal industry. With no part preparation or special fixturing required. Resonant Acoustic Method NDT uses a simple impact and resulting acoustic resonance to test parts as fast as one part per second. NDT-RAM detects defects such as cracks, chips, missed processes and porosity on 100% of manufactured parts. THE ROSE CORPORATION www.therosecorp.com The Rose Corporation, located in Reading, PA, an exclusive licensee of the Drever Company, is a leading manufacturer of thermal equipment specializing in powder reduction, sintering and bright annealing. In addition, we offer custom furnaces for heat treatment, forging and reheating along with controlled-atmosphere-generating equipment. Whether the requirement is consultation, new equipment, turnkey installation, custom design or equipment upgrade, our skilled personnel and 150,000 sq. ft. manufacturing facility can be your singlesource solutions. THERMAL TECHNIC www.thermaltechnic.com Thermal Technic provides exceptional-quality alloy muffles and wire-mesh belts to manufacturers of PM parts and manufacturers of powder. Our muffles and belts are designed for the individual customer’s specific process. With this attention to detail, our goal is to provide belts and muffles that extend service life and minimize costly furnace shutdowns.

METAL POWDER PRODUCERS ACUPOWDER INTERNATIONAL, LLC www.acupowder.com ACuPowder, with plants in NJ & TN, is a major U.S. producer of metal powders. Products include: antimony, bismuth, brass, bronze, bronze premixes, chromium, copper, copper oxide, copper premixes, diluted bronze premixes, graphite, high-strength bronze, infiltrant, manganese, MnS+, nickel, phos copper, silicon, silver, tin, tin alloys and PM lubricants. New products include powders for MIM, thermal management. "Green Bullets," leadfree solders, copper brazing, plastic fillers and cold casting. AMERICAN CHEMET CORPORATION www.chemet.com American Chemet Corporation, founded in1946, is a manufacturer of copper powders, copper oxides, zinc oxide and dispersionstrengthened copper. Chemet's oxide-reduced copper powders excel in such applications as: iron powders addition for PM, friction materials, MIM, lubricants, brazing, sintered tungsten, diamond cutting tools, carbon brush and catalyst. AMETEK SPECIALTY METAL PRODUCTS www.ametekmetals.com Major producer of stainless steel and high-alloy powders for PM, filtration, MIM, and thermal spray. Fully dense consolidation capability via proprietary pneumatic isostatic forging (PIF) process to make bars, rods, and specialty shapes from a wide variety of alloys. Full range of thermal management products like AlSiC, copper-tungsten, copper-molybdenum, and copper clad-copper/molybdenum copper heat sink for telecommunication, advanced radar systems,

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and other high-heat-dissipation requirements. ARC METALS CORP. www.arcmetals.com ARC Metals is the industry leader in the production of remill materials. ARC Metals also offers custom blending and full metallography with in house technical support. ASBURY GRAPHITE MILLS, INC. www.asbury.com Asbury Graphite Mills, Inc., and its Southwestern Graphite Division continue to be the world leader in supply of quality and consistency of graphite and carbon powders for admix applications. Since the inception of the powdered metal industry, Asbury has been providing both natural and synthetic graphite products for every application. Asbury also offers graphite-based lubricants and sintering trays to the industry. For strength and dimensional stability, choose Asbury. BASF CORPORATION www.basf.com/cip Carbonyl Iron Powders: BASF has the most diversified range of Carbonyl Iron Powders and is a leader in product innovation. In cooperation with a broad range of customers, BASF has successfully developed differentiated grades geared to the individual needs of specific niche applications. BASF powders are widely used for iron-nickel and low-alloy steels, as well as in MIM master alloy techniques. CRUCIBLE RESEARCH www.crucibleresearch.com Crucible Research is a manufacturer of high-quality, spherical prealloyed metal powders including titanium, nickel, copper, cobalt, and iron-base alloys. They provide technical expertise and partnership in programs from new alloy development through powder production and component manufacturing. Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

ECKA GRANULES OF AMERICA L.P. www.ecka-granules.com ECKA Granules is the leading manufacturer for nonferrous metal powders. The product range includes aluminum, magnesium, copper, calcium, tin, lead, zinc, silicon and their alloys as well as ready-to-press blends. Production techniques include milling and grinding, electro-deposition, air, water, and gas atomization, granulation for melting and recycling processing. ERAMET MARIETTA, INC. www.emspecialproducts.com Eramet Marietta, Inc., produces a complete range of chromiummetal and carbide powders that are used in a broad range of applications. Included are thermal sprays, powder metallurgy parts, consumable electrodes for welding, hard-facing applications, sputtering targets, and infiltrants. Eramet’s unique electrolytic and vacuum facilities at Marietta, Ohio, produce an environmentally friendly product that meets the chemistry and sizing requirements of these diverse applications. For more information, visit www.emspecialproducts.com ECKART AMERICA CORPORATION www.eckart.net Eckart, the world’s leading producer of aluminum powders and pastes, now offers the SDF series of products, produced in the USA, by Eckart America Corporation based in Louisville, KY. The Aluminum SDF series features a full line of powder; this product line provides a range of particlesize distribution designed to meet most market needs. Our products supported with responsive technical support to provide customers with cost-effective solutions across a wide range of applications. Eckart America Corporation is registered ISO 9000 vs 2000. Phone 502-775-4842.

HENGYUAN METAL & ALLOY POWDERS LTD. www.hengyuanpowders.com Hengyuan Metal & Alloy Powders Limited supplies a variety of fine and ultrafine metal and alloy powders for powder metallurgy and metal injection molding applications. (1) Copper and copper-alloy powders, stainless steel powders. (2) Ferro-molybdenum, ferro-manganese, low-carbon ferro-chromium, high-carbon ferro-chromium, ferro-phosphorus, ferro-boron, ferro-titanium and other ferroalloy powders. HOEGANAES CORPORATION www.hoeganaes.com Hoeganaes Corporation, world leader in ferrous powder production, has been a driving force within the PM industry for 55 years. The company has seven manufacturing facilities in the USA and Europe to meet customers' needs worldwide. It continues to invest in manufacturing capacity to support industry growth while providing design, process and material system education worldwide. Hoeganaes holds these certifications: ISO 14001, ISO/TS 16949, and ISO 9001, QS 9000. INCO SPECIAL PRODUCTS www.incosp.com Inco Special Products is a dedicated business unit of CVRD Inco, the World's Leading Nickel Company. Refineries in North America and Europe produce carbonyl nickel powders of various shapes, sizes and morphologies to the ISO9002 standard; PM products include INCO T123 PM, the powder metallurgy industry Ni powder standard; T255, a fine, filamentary Ni powder for increased dimensional control; and T110 PM, a new extra-fine Ni powder for high-performance applications.

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INDUSTRIAL METAL POWDERS (INDIA) PVT. LTD. www.imp.net.in Industrial Metal Powders is an ISO 9001 company and one of the largest manufacturers of electrolytic iron powders in the world with 30 years of experience. It manufacturers high-purity powder (Fe – 99.5/minimum) for diamond tools, magnetic core, food grade FCC for fortification. KOBELCO METAL POWDER OF AMERICA, INC. www.kobelcometal.com Kobelco Metal Powder of America, Inc., a subsidiary of Kobe Steel, Ltd., is a major U.S. producer of high-quality, water-atomized ferrous powders, prealloy powders and premixes for use in the PM and related industries. An ISO/TS-16949 certified company, Kobelco offers complete production and laboratory facilities for testing and development activities. MAGNESIUM ELEKTRON POWDERS www.magnesium-elektron.com Magnesium Elektron Powders, a world leader in the manufacture of magnesium particulate, is a producer of both ground and atomized powders. Ground products include standard and ultrahigh-purity magnesium chips and granules, coarse and fine powders, and magnesium/aluminum alloy powders. Our atomized and ground powders are specially sized and shaped for a number of applications including powder metallurgy and Military Countermeasure Flares. For more information visit our Web site: www.magnesium-elekton.com METALPÓ IND. E COM. LTDA. www.metalpo.com.br Since its opening, in 1967, Metalpó has had its activities pointed to powder metallurgy as a nonferrous powders and sintered parts producer. Typical Metalpó powder metallurgy products are

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self-lubricating bearings (bronze and iron), structural parts (iron, stainless steel, bronze and brass) and metal powders (copper, bronze premix, prealloyed bronze and tin). Using modern methods and quality management systems Metalpó has had since its early years the acknowledgment for highest level of quality. This has earned the Metalpó quality management system the ISO 9001/2000 and ISO TS 16949 assessments. NORTH AMERICAN HÖGANÄS, INC. www.nah.com North American Höganäs, Inc., a subsidiary of Höganäs AB, is a supplier of iron-based metal powders and stainless steel powders designed for a broad spectrum of applications, including components, friction, welding, brazing, thermal coating, soft magnetic composites, electro photographic and numerous chem/met applications. Production takes place in four strategic locations: Stony Creek Plant, located in Hollsopple, PA, is the world's most integrated production resource for atomized iron and steel powders. St. Marys Plant, located in St. Marys, PA, is a mixing facility which is capable of producing small to truckload-size custom mixes. Niagara Falls Plant, located in Niagara Falls, NY, produces a comprehensive range of products ranging from friction materials, powder metallurgy and soft magnetics, to food additives and general chemical use. Johnstown Plant, located in Johnstown, PA, produces a broad range of products including stainless steel powders, iron-alloy powders, nickel-alloy powders, electrolytic iron powders and chips, manganese and silicon powders, and GLIDCOP® dispersionstrengthened copper products.

OM GROUP (OMG) www.omgi.com OM Group is a leading, vertically integrated international producer and marketer of value-added, metal-based specialty chemicals and powders. With more than 30 years of experience in cobalt powders, OMG serves the needs of not only hardmetal and diamond tool industries but also PM, batteries, magnets and many other specialty applications. Headquartered in Cleveland, Ohio, OM Group operates manufacturing facilities in the Americas, Europe, Asia and Africa. For more information, visit our Web site at http://www.omgi.com. QMP AMERICA www.qmp-powders.com QMP, registered to ISO 9001, ISO 14001, and ISO/TS 16949, provides a full product line of iron and steel powders in the Americas, Europe, and Asia. ATOMET standard grades and prealloys, binder treated FLOMET™ mixes, diffusion-bonded ATOMET DB powders, machinable (sulphur-free) grades, sinter-hardening grades, and soft magnetic composite materials are available to customers worldwide. SCM METAL PRODUCTS, INC. www.scmmetals.com With manufacturing facilities in the U.S. and China and a global distribution network, SCM supplies a wide array of powdered metal powders including copper, copper oxide, copper flake, premixed and prealloyed bronze, alloyed brass, tin, and copperalloy pastes for brazing and infiltrating. SCM also offers a wide array of MIM powders including stainless steel and copper. Visit us at www.scmmetals.com. TITAN METAL POWDERS www.titanmetalpowders.com Titan Metal Powders produces or supplies a wide variety of metals and alloys, either as powder in an Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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assortment of micron sizes or as other physical forms. We can offer product customization through our wide range of manufacturing and processing capabilities and services. Standard products include: molybdenum, ferromolybdenum, tungsten, ferrotungsten, cobalt, rhenium, nickel, nickel-boron, nickel-niobium, aluminum, aluminum silicon, silicon, ferro-silicon, chromium, chromium carbide, ferro-chromium, ferro-niobium, ferro-boron, and ferro-vanadium. We also buy, process and upgrade scrap. UMICORE www.umicore.com Umicore Tool Materials is a business line of Umicore, serving the markets of diamond tools and hardmetal applications. We offer a wide range of cobalt powders, nickel powders and prealloyed alternatives (from our Cobalite range). Being a worldwide market leader, we see successful use of our products in tools for stonecutting and construction, as well as hardmetal or cemented carbide applications. Our products provide the perfect solution to create bonds with other constituents like diamonds or tungsten carbide. Due to our extensive application know-how and R&D facilities, we can provide you with the necessary technical support. UNITED STATES BRONZE POWDERS, INC. www.usbronzepowders.com Major global producer of nonferrous metal powders and flakes, including aluminum, aluminum premixes, copper, copper alloys, bronze premixes, nickel silver, infiltrants, and tin. The company has 3 manufacturing facilities in the U.S., one in France, and one in the UK.

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

MIM/PIM ADVANCED METALWORKING PRACTICES, LLC. www.advancedmetalworking.com Producer of high-quality feedstock for MIM since 1988—longer than any other supplier. ADVAMET® feedstocks are available for many steels and stainless steels and some nonferrous compositions. We can customize feedstocks for different target shrinkages. Ontime shipments of feedstocks in tonnage quantities. Test lots for new customers or new applications. Visit our Web site for more information about the consistent quality of our feedstocks, discussion of dimensional precision, and background. AMETEK SPECIALTY METAL PRODUCTS www.ametekmetals.com Major producer of stainless steel and high-alloy powders for PM, filtration, MIM, and thermal spray. Fully dense consolidation capability via proprietary pneumatic isostatic forging (PIF) process to make bars, rods, and specialty shapes from a wide variety of alloys. Full range of thermal management products like AlSiC, copper-tungsten, copper-molybdenum, and copper clad-copper/molybdenum copper heat sink for telecommunication, advanced radar systems, and other high-heat-dissipation requirements. BASF CORPORATION www.basf.com/catamold BASF Catamold® is a ready-tomold feedstock for MIM and CIM. Our material portfolio includes various low-alloy steels, stainless steels, tool steel, soft magnetic alloys, super alloys, special alloys (Ti, W, others) and oxide ceramics. New grades will be developed as needed for our customers. Catamold ® incorporates catalytic debinding and offers high green

strength and dimensional stability. It is well suited for both batch and continuous PIM operations. www.basf.com/catamold. DSH TECHNOLOGIES, LLC www.dshtech.com MIM consultants with in-house capabilities of debinding and sintering in production-scale equipment. Services offered include: Consulting: DSH consults on all aspects of the MIM process, from R&D and prototype development, to the set-up of turnkey production operations and facilities. Partnering/Joint Venture: DSH can partner with you for either new-product development or could be your outsourcing resource for your R&D project from start-up to full production. Toll Debinding & Sintering: DSH will debind and sinter your parts, be they samples or production runs. DYNAMIC ENGINEERING INC. www.dynamicengr.com Dynamic Engineering designs and manufactures precision production injection molds for powder and plastic. Established in 1977. Manufacturing powder injection molds since 1988. Dynamic's molds have produced parts that were awarded the MPIF/MIM "Part of the Year" at least five times. Servicing the Dental, Medical, Telecommunications, Automotive, Firearms and Consumer industries. Wideranging experience including multi-shot (two or more) molds for PIM. Specializing in molds for small, complex parts. FLOMET LLC www.flomet.com FloMet is an ISO 9001:2000 registered manufacturer of precision, high-volume metal components through metal injection molding (MIM). Materials include stainless steel, metal-to-glass sealing alloys, copper alloys, controlled expansion alloys and others.

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Markets served include medical, electronics, fiber optics, hermetic packaging, orthodontics, consumer products and other OEMs who use high-volume metal components. Our 20 years of experience puts cost-saving parts into production. MATERIALS PROCESSING, INC. www.mpi-pim.com MPI is the industry leader in fabricating large, complex-shaped powder injection molded parts from hardmaterials. MPI, founded in 1999, fabricates difficult-toform advanced materials (hardmetals, cermets, hightemperature materials) using the PIM process. Our focus is in the area of high-wear- and abrasionresistant components that are complex shaped (nozzles for oil and gas industry, knives for the plastic industry, twist blades, etc., made from hardmetals). MPI is capable of fabricating both small and large hardmaterial parts by PIM. MPI works with customers to tailor a grade of hardmaterial to provide solutions for their wear- and abrasionrelated applications. NETSHAPE TECHNOLOGIES, INC. www.netshapetech.com A manufacture of engineered, complex, high-strength components using powder metallurgy and metal injection molding! NetShape is a Lean-focused, global supplier with 5 PM and 1 MIM operations worldwide, including a facility in Suzhou, China. Industry-leading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneeing® process and strong engineering support offer unmatched value and support for converting parts to PM.

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PHILIPS ADVANCED METAL SOLUTIONS www.philips.com/ams Philips Advanced Metal Solutions, global development center for Philips Lighting, is a specialist producer of tungsten and molybdenum components serving many applications in various industries. We combine our technical expertise in alloying, material engineering and shaping technologies like lasering & MIM with our underlying philosophy—“designed around you.” This enables us to deliver the refractory metal products that you need in a reliable and costeffective way. Please visit www.philips.com/ams PLANSEE USA www.plansee-usa.com Schwarzkopf Technologies is now PLANSEE USA and continues to deliver the world’s best furnace solutions. Schwarzkopf Technologies is known within the U.S. and Canada as the industry leader in developing, designing, and manufacturing high-temperature furnace products to perform better and last longer. As an independent subsidiary we have contributed to the success of the PLANSEE Group— going forward we will be operating jointly under one name. Our customers will be able to benefit even more from synergies generated within the Group, demonstrating our uncompromising commitment to delivering the highest-quality products. REMINGTON ARMS COMPANY, INC., Powder Metal Products Division www.remingtonpmpd.com The Powder Metal Products Division has been a MIM parts producer since the mid-1980s and continues to supply Remington and a number of commercial customers with high-

quality MIM parts, in mediumto-high volumes. We offer lowalloy steels, stainless steels, and soft magnetic materials for many markets, including automotive, ordnance, and medical applications. Please visit our Web site at www.remingtonpmpd.com to learn more about MIM technology and our MIM product offering. SCHWARZKOPF TECHNOLOGIES LLC www.plansee-usa.com Schwarzkopf Technologies is now PLANSEE USA and continues to deliver the world’s best furnace solutions. Schwarzkopf Technologies is known within the U.S. and Canada as the industry leader in developing, designing, and manufacturing high-temperature furnace products to perform better and last longer. As an independent subsidiary we have contributed to the success of the PLANSEE Group— going forward we will be operating jointly under one name. Our customers will be able to benefit even more from synergies generated within the Group, demonstrating our uncompromising commitment to delivering the highest-quality products. SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures high-temperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as micro-porous kiln furniture. We are also a distributor for Ferro Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004.

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OTHER ALLEGHENY COATINGS www.alleghenycoatings.com Allegheny Coatings, located in Ridgway, PA, is an ISO 9001 registered applicator of coatings and platings for use on powdered metals. These applications provide for lubricity, as well as corrosion, heat, and wear resistance. Resin and inorganic impregnation are also available. In addition, Allegheny Coatings offers unique coating services such as part masking, cyclical corrosion testing, and a variety of chromefree coatings. Web site: www.alleghenycoatings.com. APEX ADVANCED TECHNOLOGIES www.apexadvancedtechnologies.com Apex is the leader in innovative development for lubricants and binders in the powdered metal industry. We analyze the needs of the industry and through innovation develop unique solutions that create value for the client and industry at large. Our products include Superlube®, Enhancer, a high-strength binder, and our near-full-density systems for powdered metal. CHEMETALL www.chemetall.at Chemetall Ges.m.b.H. Metal sulfides are employed in powder metallurgy. Synthetic sulfides such as tungsten or tin sulfides as well as multi-phase sulfides of various particle shapes and sizes decisively improve the machinability of sintered parts. Sintered parts are used in highperformance applications where resistance to high loads and temperatures is demanded. GLOBAL PM CONSULTANTS www.globalpm.net Specializing in: PIM technology, metal powder production technology. Structural parts production

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

technology incl. tooling, compaction and sintering. PM materials technology, properties and applications, PM semi-finished, fully dense and hard materials. Services offered: Market research, technical forecasting and technology assessments; business developments; global licensing and technology transfer; international strategic partnership formation; reviews of international development trends; industrial applications of PM products and selection of PM materials; international recruitment consultancy. JENIKE & JOHANSON, INC. www.jenike.com Jenike & Johanson, in business over 40 years, is an experienced consulting and engineering firm that specializes in powder flowability and engineering system for powders. We have a full service powder test lab to determine powder flow properties and behavior. We troubleshoot existing systems and design new processes to store, transport, feed, and reliably deliver powder consistently. We provide modeling, functional design, detailed design, and courses on powder flow to clients worldwide. KITTYHAWK PRODUCTS www.kittyhawkinc.com Kittyhawk Products—qualified experts in the field of hot isostatic processing. HIP is an affordable process of unique benefit in solving complex design problems while increasing the strength of properties. Together with our sister company, Synertech P/M Inc., we offer unmatched net-shape capabilities with powder metal parts design and manufacture. METAL POWDER REPORT Metal Powder Report covers the powder metallurgy industry worldwide. Each issue carries up-to-date news and features on technical trends in the manufac-

ture, research and use of metal powders. Metal Powder Report is the only monthly international magazine covering the powder metallurgy industry. PLASMA PROCESSES, INC. www.plasmapros.com Plasma Processes, Inc. (PPI) is an ISO 9001:2000 certified business specializing in advanced materials and coating technologies. PPI's Powder Alloying & Spheroidization™ technology transforms flaky, angular powders into spheres & spherical alloys. In addition, PPI develops, applies and validates coating solutions for thermal protection, electrical isolation, wear and corrosion resistance and dimensional restoration, in addition to the manufacture of net-shape components by vacuum plasma and El-Form™ electrodeposition processes. PRINCETONONE www.PrincetonOne.com PrincetonOne is one of the world’s most successful recruiting firms serving the powder metal industry and related industries. Brian Orges, Industry Practice Manager, has placed professionals within the powder metal industry for the past 15 years, and continues to be one of the top performers within his company and the industry providing retained, priority and contingency search to his clients. PSM INDUSTRIES, INC. www.psmindustries.com A symphony of PM solutions. Our 6 manufacturing divisions will find an answer to your most pressing PM problem. Specialties include high-dense high-speed steels, high-shape-complexity MIM and PM, steel-bonded carbides, tungsten carbides, highconductivity copper, and a wide variety of other specialties. Come visit our Web site at www.psmindustries.com.

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QUALA-DIE, INC. www.quala-die.com Quala-Die, Inc. is the leader in powder metal tooling and precision machining. From design through production Quala-die can provide you with superior service and quality. RESCO PRODUCTS, INC, (Shenango Advanced Ceramics, LLC) www.rescoproducts.com New Castle Refractories and Shenango Advanced Ceramics have now joined the Resco Products family. Resco Products is a leading supplier of refractories in North America serving major industries such as steel, copper, nickel, aluminum, hydrocarbon processing and cement with a full line of refractory products.

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for PM due to the differences between iron-carbon, Fe-Cu, FeNi, low-alloy, as-sintered, copperinfiltrated, steam-treated, hardened, sinter-hardened, and powder-forged components. SINTER-PACIFIC (a Div. of International Sintered Components Pty Ltd) www.sinter-pacific.com Sinter-Pacific was established in October 1993 with a focus on providing our Asia Pacific customers with cost-effective design solutions using powder metal technology from the world’s best. Diversification has now provided PM products, specialty dry bearing technology, PM processing machinery & equipment along with NDT solutions for our customers.

RYER, INC. www.ryerinc.com Ryer, Inc., is a manufacturer, developer and supplier of custom and standard feedstocks for the metal injection molding industry. We offer the widest range of particle sizes, material types and debinding methods in the MIM industry. As a custom compounder, Ryer can match your current material shrink specifications and flow characteristics. Ryer Feedstocks are inspected, tested and documented to assure you receive consistent, predictable results with "batch to batch" repeatability.

SUPERIOR GRAPHITE CO. www.superiorgraphite.com Superior Graphite specializes in thermal purification, advanced sizing, blending, and coating technologies, providing valueadded graphite and carbon-based solutions globally. Combining 90 years of experience and advanced technologies into every facet of the organization, a wide range of markets are served such as: agriculture, battery/fuel cells, ceramic armor, carbon parts, ferrous/nonferrous metallurgy, friction management, hot metal forming, polymer/composites, powder metals, lubricity, and performance drilling additives.

SHAPE-MASTER TOOL COMPANY www.shapemastertool.com Shape-Master Tool manufactures polycrystalline cubic boron nitride (PCBN) cutting tools for PM machining. With a metallurgical engineer on staff, Shape-Master understands PM and nuances of PM machining optimization. We don't offer a single solution for all PM alloys because it's simply not possible. Shape-Master utilizes over eight different PCBN grades

TIMCAL GRAPHITE & CARBON www.timcal.com TIMCAL Graphite & Carbon is committed to produce highly specialized graphite and carbon materials for today's and tomorrow's powder metallurgy industries. TIMCAL Graphite & Carbon is a global leader in realizing customer solutions in graphite and carbon applications and is a member of IMERYS, a world leader in adding value to minerals.

ULTRA INFILTRANT www.ultra-infiltrant.com Ultra Infiltrant is a wrought, homogeneous copper-based alloy that offers significant benefits over powder-form copper infiltrants. Benefits like less waste, improved productivity and increased strength. Ultra Infiltrant is available in custom configurations to accommodate virtually any automated process. Ultra Infiltrant was designed for copper infiltration of ferrous PM parts in today's cost-competitive manufacturing environments, where the handling of fragile green infiltrant slugs is difficult and can lead to excessive waste.

PM PRODUCTS OR PARTS PRODUCERS ACE IRON & METAL CO., INC. Ace Iron & Metal is a full-service metal recycling company in business since 1945. We purchase all types of powder metal scrap inclusive of green, sinter-floor sweeps, and all maintenance scrap, along with furnace scrap. We can be contacted via our e-mail address or our toll free number. [email protected] ALPHA SINTERED METALS, INC. www.alphasintered.com Alpha Sintered Metals, Inc., is a designer and manufacturer of multilevel, high-precision, structural powdered metal components, such as spur, bevel, and helical gears; sprockets; cams; and flanges. These components are used primarily in small engines, transmissions and mechanical drive applications for the outdoor power equipment (including lawn and garden), automotive, and general industrial markets. With our experienced engineers and metallurgical staff, Alpha Sintered Metals, Inc., a has been producing quality powdered metals parts for over 40 years. ASM is ISO Certified.

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ALLREAD PRODUCTS LLC www.allreadproducts.com Allread Products is a very versatile company which will manufacture large or small volumes of parts. Our pressing capabilities range from 4 ton presses up to 100 ton presses. We process multitudes of materials including ferrous and ferrous alloys, most nonferrous, stainless steel, aluminum, and Teflon. Our secondary department is quite extensive including 6 CNC machines and a number of small automatic machines for special applications. Along with these capabilities we also do assembly of various parts. ASCO SINTERING CO. www.ascosintering.com Manufacturer of precision complex multilevel structural powdered metal parts & assemblies. Experienced sintered metal engineering & metallurgical staff. Serving the automotive, lock, hardware, lawn & garden, irrigation, medical, hand tools, computer & cutlery industries. Capabilities include tool design, tooling, metallurgy, warm compaction, high-temperature sintering, sinter hardening, heat treat, resin impregnation, deburring, secondary machining, assembly & plating. Materials include lowalloy, diffused, copper, carbon & infiltrated steels, 300 & 400 stainless steels, brass, nickel silver, Monel®, soft magnetics, copper & bronze. ATLAS PRESSED METALS www.atlaspressed.com Atlas Pressed Metals has been a producer of powdered metal components since 1976. Atlas specializes in production of highperformance bearings, structural and gear components using iron, iron alloys, soft magnetic alloys, stainless steel, bronze, brass and custom materials.

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

BODYCOTE HIP www.bodycote.com Bodycote is the world's leading provider of metallurgical services. Hot isostatic pressing (HIP) of PM components is just one of the many services that Bodycote provides, from CAM designs and fabrication to powder filling evacuation, sealing and HIP. CMW INC. www.cmwinc.com CMW creates high-performance metallurgical products and supports customers worldwide with innovative service, metallurgical expertise and application knowledge. CMW operates in three primary business units: electrical contacts, high-density tungsten metals and resistance welding consumables. Our company has been recognized repeatedly for its safety, quality and continuous improvement programs. Our high-density tungsten metals are produced from powdered metals by liquid-phase sintering techniques. Applications range from gyroscopes and ballasts to radiation shielding and die-cast tooling. Markets include aerospace, military, high-performance electronics and more. COMPAX, INC. www.compaxinc.com Compacting equipment from 2 tons to 250 tons. High-temperature sintering capability up to 3,000°F (1,650°C). Short-, medium-, and high-volume capabilities. Secondary operations including drilling, turning, grinding, impregnation, deburring, tapping and assembling. Materials include stainless steel, nickel steel, copper steel, iron, low-alloy steel, copper, brass, bronze, aluminum, nickel silver, tungsten, 50/nickel/50 iron, copper-infiltrated steels and many specialty alloys. Types of parts include gears, magnetic pole pieces, cams, thrust bearings, bushings, com-

plex multi-level parts and twoand three-piece construction parts sintered as one. FMS CORPORATION www.fmscorporation.com FMS Corporation is a precision manufacturer of high-performance sintered metal components, serving the off-road vehicle, aerospace, computer and home appliance industries, among others. Material capabilities include highperformance, high-density steels, stainless steel, soft magnetic materials, and many nonferrous alloys. Production capabilities include in-house tool design and manufacture, conventional and wire EDM, compaction from 2 to 1,100 tons, high-temperature vacuum sintering, CNC machining, grinding, lapping, resin and oil impregnation. KEYSTONE POWDERED METAL COMPANY www.keystonepm.com Keystone Powdered Metal Company is a leading powder metal parts supplier to the automotive OEMs, automotive Tier I and Tier II manufacturers. Keystone provides its customers with highly engineered products which utilize the industry’s most advanced technologies and material systems. Primary products include planetary carriers, pinion gears, parking gears, transmission sprockets, engine-timing sprockets and assembled one-way clutches for use in automotive powertrain applications. LOVEJOY SINTERED SOLUTIONS LLC www.lovejoy-LSS.com Low-volume, high-density, complex parts producer of ferrousbased components including soft magnetics. Presses range from 65T to 1,000T, ISO 9001 certified. In-house CNC equipment includes turning, boring, drilling, tapping, broaching. Also coining,

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sizing, deburring, tool design, with CAD/CAM and Pro-E. Full range of gauging inspection equipment, gear-inspection equipment including CMM. Fully automated from press to sinter. Parts include stators, rotors, gears, counterweights, rings, etc. Aspect ratios reaching 10:1. METALPÓ IND. E COM. LTDA. www.metalpo.com.br Since its opening, in 1967, Metalpó has had its activities pointed to powder metallurgy as a nonferrous powders and sintered parts producer. Typical Metalpó powder metallurgy products are self-lubricating bearings (bronze and iron), structural parts (iron, stainless steel, bronze and brass) and metal powders (copper, bronze premix, prealloyed bronze and tin). Using modern methods and quality management systems Metalpó has had since its early years the acknowledgment for highest level of quality. This has earned the Metalpó quality management system the ISO 9001/2000 and ISO TS 16949 assessments. METAL POWDER PRODUCTS COMPANY www.metalpowderproducts.com Metal Powder Products Company is an international provider of custom-engineered powder metallurgy product solutions to customers in a variety of industries. MPP has developed a number of innovations in material formulation, sintering, densification, powder metallurgy joining techniques, and value-added secondary operations. MPP is the largest manufacturer of powder metal aluminum structural parts in North America. METALDYNE SINTERERED COMPONENTS www.metaldynepowdermetal.com Metaldyne, An Asahi Tec company, is a world leader in the Powder Metallurgy (PM) industry,

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offering complete customerfocused solutions for high-performance automotive components. Extensive engineering research and development stands behind each and every product. Metaldyne is the largest powder forged connecting rod provider in the world, manufacturing more than 50 million per year. Metaldyne also designs and manufacturers a variety of other powder metal products for automotive manufacturers around the world. METCO INDUSTRIES www.metcopm.com Metco Industries, Inc., has molding capabilities up to 400 ton including multi-action for ferrous and nonferrous applications. Advanced secondary machining facility on site for quicker response to customer demands. Celebrating 25 years of PM excellence in the automotive, lawn & garden, recreational vehicle, healthcare and commercial markets. MI-TECH METALS, INC. www.mi-techmetals.com Mi-Tech Metals, Inc., located in Indianapolis, Indiana, produces tungsten heavy alloy and copper and silver tungsten composite materials. Additional materials include tungsten carbide and pure molybdenum and tungsten. Mi-Tech maintains inventory to meet immediate requirements and our extensive machine shop manufactures parts to p???? MOTT CORPORATION www.mottcorp.com Mott Corporation has been providing unique solutions in the development and application of porous metal media since 1959. Mott partners with customers in many industries to engineer and design porous metal products with very specific tolerances and attributes. Mott is ISO 9001:2000 Certified and also maintains Class 100 and Class 10,000 clean

room environments. Visit our Web site www.mottcorp.com for our complete line of porous metal capabilities and products. NETSHAPE TECHNOLOGIES, INC. www.netshapetech.com A manufacture of engineered, complex, high-strength components using powder metallurgy and metal injection molding! NetShape is a Lean-focused, global supplier with 5 PM and 1 MIM operations worldwide, including a facility in Suzhou, China. Industry-leading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneeing® process and strong engineering support offer unmatched value and support for converting parts to PM. NOVAMET SPECIALTY PRODUCTS CORPORATION www.novametcorp.com Novamet Specialty Products Corporation, a CVRD Inco Company, is a producer of specialty metal and metal oxide powders. Carbonyl nickel powders are classified to narrow size ranges for a variety of applications, including metal injection molding. The Novamet family of Type 4SP nickel powders is the preferred MIM industry choice. Four size ranges are available, -400 mesh, 20 micron, -20 + 10 micron and 10 micron. PHILIPS ADVANCED METAL SOLUTIONS www.philips.com/ams Philips Advanced Metal Solutions, global development center for Philips Lighting, is a specialist producer of tungsten and molybdenum components serving many applications in various industries. We combine our technical expertise in alloying, material engineering and shaping technologies like lasering & MIM with our underlying philosophy—“designed around

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you.” This enables us to deliver the refractory metal products that you need in a reliable and costeffective way. Please visit www.philips.com/ams PLANSEE USA www.plansee-usa.com Schwarzkopf Technologies is now PLANSEE USA and continues to deliver the world’s best furnace solutions. Schwarzkopf Technologies is known within the U.S. and Canada as the industry leader in developing, designing, and manufacturing high-temperature furnace products to perform better and last longer. As an independent subsidiary we have contributed to the success of the PLANSEE Group— going forward we will be operating jointly under one name. Our customers will be able to benefit even more from synergies generated within the Group, demonstrating our uncompromising commitment to delivering the highest-quality products. PLANSEE SE www.plansee-group.com The Plansee Group is one of the world’s leading suppliers of powder metallurgical products and components. The industrial portfolio of Plansee Group is structured into three divisions: PLANSEE High Performance Materials, CERATIZIT Hardmetals & Tools and PMG PM–Products. Ignoring differing shares of the ownership, the Group achieved worldwide sales of over 1.4 billion euros in the 2006/07 fiscal year, and employed a total of 8,800 people. www.plansee-group.com PSM INDUSTRIES, INC. www.psmindustries.com A symphony of PM solutions. Our 6 manufacturing divisions will find an answer to your most pressing PM problem. Specialties include high-dense high-speed

Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

steels, high-shape-complexity MIM and PM, steel-bonded carbides, tungsten carbides, highconductivity copper, and a wide variety of other specialties. Come visit our Web site at www.psmindustries.com. SCHWARZKOPF TECHNOLOGIES LLC www.plansee-usa.com Schwarzkopf Technologies is now PLANSEE USA and continues to deliver the world’s best furnace solutions. Schwarzkopf Technologies is known within the U.S. and Canada as the industry leader in developing, designing, and manufacturing high-temperature furnace products to perform better and last longer. As an independent subsidiary we have contributed to the success of the PLANSEE Group— going forward we will be operating jointly under one name. Our customers will be able to benefit even more from synergies generated within the Group, demonstrating our uncompromising commitment to delivering the highest-quality products. SMC POWDER METALLURGY www.smcpowdermetallurgy.com SMC Powder Metallurgy is a 57year young PM manufacturer, diverse in the materials supplied, the business markets served, and the parts manufactured. SMC Powder Metallurgy manufactures in a modern 112,000 sq. ft. facility located in Galeton, Pennsylvania, dedicated solely to the manufacturing of powder metal components. SMC Powder Metallurgy is TS-16949 certified company. For additional detail, please visit our Web site at www.smcpowdermetallurgy.com. STACKPOLE LIMITED www.stackpole.com Our mission is to be recognized as the world's premier manufac-

turer of highly engineered technologically differentiated powertrain components, systems, and assemblies. STERLING SINTERED TECHNOLOGIES www.sterlingsintered.com Sterling Sintered Technologies, an ISO 9001-2000 company, is an innovative leader in the manufacture of powdered metal components. The Sterling team works with customers to concurrently design parts and processes for them. This approach has allowed Sterling Sintered and its customers to develop new applications and push PM technology to the forefront of our industry. Let Sterling Sintered do this for you. For additional information explore our Web site at www.sterlingsintered.com VOLUNTEER SINTERED PRODUCTS, INC. www.volunteersintered.com Established 1981, family owned/operated Press Range 20–200 Ton Materials include iron, prealloyed steels, brass, bronze, stainless Parts include gears, bearings, structurals, cams, etc. Secondary operations – copper infiltrating, brazing, coining, burnishing, drilling, tapping, turning, oil impregnation, deburring Inspections/QC ISO 9001 certified, Rockwell hardness, gear tester, optical comparator, surface finish, crush tester Specialties complex, close-tolerance parts, short lead times for tooling and production WESTERN SINTERING CO. INC. www.westernsintering.com Manufacturer of custom powder metal parts. Presses to 300 tons. Steel, stainless steel, and copperbase materials. Complete secondary facilities and heat treat in-house.

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MEETINGS AND CONFERENCES

2008 3RD INTERNATIONAL CONFERENCE ON STRUCTURE, PROCESSING, AND PROPERTIES OF MATERIALS February 14–16 Dhaka, Bangladesh PM08 INTERNATIONAL CONFERENCE & EXHIBITION February 20–21 Chennai, India www.pmai.in/pm08 PIM2008 March 10–12 Long Beach, CA MPIF* SAE WORLD CONGRESS & EXPOSITION April 14–17 Detroit, MI www.sae.org HIP ’08—THE 9TH INTERNATIONAL CONFERENCE ON HOT ISOSTATIC PRESSING May 6–9 Huntington Beach, CA www.hip2008.com 2008 WORLD CONGRESS ON POWDER METALLURGY & PARTICULATE MATERIALS June 8–12 Gaylord National Hotel Washington, DC MPIF* 2008 INTERNATIONAL CONFERENCE ON TUNGSTEN, REFRACTORY & HARDMATERIALS VII June 8–12 Gaylord National Hotel Washington, DC MPIF* 19TH AEROMAT CONFERENCE & EXPOSITION June 23–26 Austin, TX www.asminternational.org/ aeromat

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BASIC PM SHORT COURSE July 21–23 State College, PA MPIF* PM SINTERING SEMINAR September TBA MPIF* 5TH INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS AND PROCESSING September 3–6 Harbin, China icamp.hit.edu.cn/ SUPERALLOYS 2008 September 14–18 Champion, PA www.tms.org/Meetings/ specialty/superalloys 2008/home.html INTERNATIONAL CONFERENCE ON ALUMINUM ALLOYS September 22–26 Aachen, Germany www.dgm.de EURO PM2008 September 29–October 1 Mannheim, Germany www.epma.com/pm2008 MATERIALS SCIENCE & TECHNOLOGY 2008 CONFERENCE & EXHIBITION October 5–9 Pittsburgh, PA www.matscitech.org/2008/ home.html SINTERING 2008 November 16–20 La Jolla, CA www.ceramics.org/sintering 2008

PMP III THIRD INTERNATIONAL CONFERENCE—PROCESSING MATERIALS FOR PROPERTIES December 7–10 Bangkok, Thailand www.tms.org/meetings/ specialty/pmp08

2009 POWDERMET2009: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 28–July 1 Las Vegas, NV MPIF* THERMEC 2009: SIXTH INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS AND PROCESSES August 25–29 Berlin, Germany

SDMA 2009/ICSF VII—4TH INTERNATIONAL CONFERENCE ON SPRAY DEPOSITION AND MELT ATOMIZATION/7TH INTERNATIONAL CONFERENCE ON SPRAY FORMING September 7–9 Bremen, Germany www.sdma-conference.de/

2010 PM2010 WORLD CONGRESS October 10–14 Florence, Italy

*Metal Powder Industries Federation 105 College Road East, Princeton, New Jersey 08540-6692 USA (609) 452-7700 Fax (609) 987-8523 Visit www.mpif.org for updates and registration. Dates and locations may change Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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MAYBE NOW’S THE TIME TO JOIN APMI INTERNATIONAL… Here’s just a sample of the benefits you receive as an APMI member International Journal of Powder Metallurgy

Publications Receive discounts on PM publications covering every aspect of powder metallurgy processing and production.

Published bi-monthly, the International Journal of Powder Metallurgy is the world’s leading and most authoritative journal covering scientific, technical, business and marketing information on the PM and advanced particulate industries. In each issue you will find expert reports on:

Employment Opportunities APMI PM Industry News Online and our Web site carry classified employment listings from companies seeking experienced PM professionals. Members seeking employment may place Position Wanted listings free of charge.

• Research and Development • Engineering and Technology • New Products • Profiles & Newsmakers • Consultants Corner • Book Reviews • Meeting Reviews

Chapter Affiliation 13 chapters throughout North America provide networking and contacts within the industry.

Annual Conference An international technical conference and exhibition co-sponsored with MPIF is held each spring. Every sixth year this is expanded into a World Congress. These important global industry events provide the best opportunity to learn first-hand about current state-of-theindustry developments. APMI members can attend at reduced rates.

Who’s Who in PM Published annually, the Who’s Who is the most widely used directory in the PM industry. It lists members of APMI International and the Metal Powder Industries Federation alphabetically and by company.

Seminars and Short Courses Industry/Technology News Receive weekly access to complete news stories published online in PM NEWSBYTES, the world’s only weekly source for breaking industry news. Full access limited to APMI members. Receive PM Industry News Online monthly featuring industry news, people in the news, classified listings, patents, meetings information, new books, courses and seminars. Plus APMI news, local chapter activities, certification, educational programs, awards and student activities are covered.

Yes, I want to be an APMI Member

Members are invited to participate in professional and educational seminars and courses covering specific areas of PM and particulate technology. Members may participate in educational activities at reduced rates.

PMT Certification The Powder Metallurgy Technologist (PMT) Certification Program was created by APMI International to recognize individuals who have demonstrated a comprehension of a specified body of knowledge encompassing the broad field of powder metallurgy and particulate materials. Members are awarded PMT certification by fulfilling specified criteria and successfully completing the required exam. Members may apply for certification at reduced rates.

Visit our Web sites: apmiinternational.org or mpif.org

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Return To: APMI International

105 College Road East Princeton, NJ 08540-6692 Tel: 609-452-7700 Fax: 609-987-8523

INTERNATIONAL

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ADVERTISERS’ INDEX

ADVERTISER

FAX

WEB SITE

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ACE IRON & METAL CO. INC. ________________(269) 342-0185 ______________________________________________6 ACUPOWDER INTERNATIONAL, LLC ___________(908) 851-4597______www.acupowder.com______________________20 AMETEK SPECIALTY METAL PRODUCTS ________(724) 225-6622______www.ametekmetals.com ____________________8 ARBURG GmbH + Co KG ____________________(860) 667-6522______www.arburg.com __________________________4 BÖHLER UDDEHOLM _______________________(603) 883-3101______www.bucorp.com _________________________11 CM FURNACES, INC. _______________________(973) 338-1625______www.cmfurnaces.com _____________________10 ELNIK SYSTEMS ___________________________(973) 239-6066______www.elnik.com___________________________12 HOEGANAES CORPORATION _________________(856) 786-2574______www.hoeganaes.com______INSIDE FRONT COVER INTERNATIONAL POWDER METAL DIRECTORY __+44 1743 369660 ____www.ipmd.net ___________________________14 NORTH AMERICAN HÖGANÄS INC. ____________(814) 479-2003______www.nah.com_____________INSIDE BACK COVER QMP ____________________________________(734) 953-0082______www.qmp-powders.com ___________BACK COVER SCM METAL PRODUCTS, INC.________________(919) 544-7996______www.scmmetals.com_______________________3 UNION PROCESS __________________________(330) 929-3034______www.unionprocess.com____________________21

ADVERTISER’S REQUEST FOR INFORMATION FAX FORM Need more information on products or services seen in this issue? Complete the form below and fax to the advertiser(s) of your choice. Fax numbers are listed in the advertisers’ index above.

international journal of

powder metallurgy

To:___________________________________ Fax #: ____________________________________________________________________ Company: _______________________________________________________________________________________________________ Please send me more information on: __________________________________________________________________________ __________________________________________________________________________________________________________________ as advertised in the __________ issue of the International Journal of Powder Metallurgy. Please send information to: Name: Title:______________________________________________________________________________________________________ Company: _______________________________________________________________________________________________________ Address: _________________________________________________________________________________________________________ City:____________________________ State:_______________ Postal Code: ____________________________________________ Country: _________________________________________________________________________________________________________ Phone:___________________ Fax:___________________ E-Mail: ______________________________________________________

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Volume 44, Issue 1, 2008 International Journal of Powder Metallurgy

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Photo Ronnie Nilsson

You buy more than metal powder – you buy knowledge!

NAH 2004/02

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RHAPSODY, Copenhagen

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Metal powders open up new possibilities for creative technical solutions. Powder components require little or no subsequent machining, achieve nearly 100% material utilization, and deliver numerous performance benefits – including the lowest total unit cost for the manufacturer. These are just some of the reasons why over 40 million powder components are produced every single day. Actually, you find more and more of them in cars, computers, household machines and electrical tools. Have the advantage on your side, contact North American Höganäs, Inc. today.

North American Höganäs Inc., 111 Höganäs Way, Hollsopple, PA 15935-6416, USA, Phone +1 8144793500, Fax +1 8144792003, www.nah.com

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