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EDITORIAL REVIEW COMMITTEE P.W. Taubenblat, Chairman I.E. Anderson, FAPMI T. Ando S.G. Caldwell S.C. Deevi J.J. Dunkley W.B. Eisen Z. Fang B.L. Ferguson W. Frazier K. Kulkarni, FAPMI K.S. Kumar T.F. Murphy P.D. Nurthen J.H. Perepezko P.K. Samal H.I. Sanderow D.W. Smith, FAPMI J.E. Smugeresky 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
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powder metallurgy Contents 2 5 7 9 11
43/6 November/December 2007
Editor's Note Newsmaker Alexander Litvintsev PM Industry News in Review PMT Spotlight On … Maryann Wright PM Metallography Competition Research & Development, Product/Process Control and Artistic Categories
25 Outstanding Poster Awards Y.I. Seo, D.H. Shin, K.H. Min, Y.D. Yoon, S-Y Chang, K.H. Lee, and Y.D. Kim; C. McClimon, J.J. Williams and N. Chawla 27 Consultants’ Corner J.T. Strauss
35 Axel Madsen/CPMT Scholar Reports P. Lapointe, C. McClimon, D. Sampson and M. Sexton
ENGINEERING & TECHNOLOGY 39 Lubricants for High-Density Compaction at Moderate Temperatures L. Azzi, Y. Thomas and S. St-Laurent RESEARCH & DEVELOPMENT 47 R&D in Support of Powder Injection Molding: Status and Projections R.M. German 59 Sintering Response & Microstructural Evolution of an Al-Cu-Mg-Si Premix J.M. Martin and F. Castro 71 72 75 77 79 80
DEPARTMENTS Meetings and Conferences APMI Membership Application Instructions for Authors Table of Contents: Volume 43, Numbers 1–6, 2007 PM Bookshelf Advertisers’ Index Cover: Metallography Competition Winner. Photo courtesy: Bruce Lindsley, Hoeganaes Corporation, Cinnaminson, New Jersey
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 © 2007 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $90.00 individuals, $210.00 institutions; overseas: additional $35.00 postage; single issues $45.00. 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:
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EDITOR’S NOTE
D
iversity characterizes the content of this concluding issue of the Journal for 2007. In-depth technical articles focus on new lubricants for achieving high density via compaction at moderate temperatures; the status and future of the powder injection molding industry, based on supporting R&D; and microstructural evolution of an aluminum alloy premix during sintering. Joe Strauss is back in the “Consultants’ Corner,” and addresses the vexing problem of variability in the flow of inert-gas-atomized powders. He also discusses heat-transfer mechanisms in sintering as a function of furnace type, and expresses a poignant viewpoint on nanomaterials. I encourage you to read the reports prepared by the four 2007 CPMT/Axel Madsen Conference Grant recipients, based on their attendance at PowderMet2007. These are frank and incisive, and demonstrate the value of the program, both to students and the PM industry. Winning entries in the APMI 2007 PM Metallography Competition are recognized (Research & Development, Product/Process Control, and Artistic categories). In the first two categories, the content provides compelling examples of problem solving in PM via metallography. The front cover, titled “Feathers,” is illustrative of the artistic/aesthetic attributes of PM materials. Also recognized are the two Outstanding Posters from PowderMet2007.
Alan Lawley Editor-in-Chief
I always look forward to reading the September issue of R&D magazine since it includes the Annual R&D 100 Awards, recognizing the world’s best innovations from academe, government, and industry. Awards were given in 19 categories, including “Life Science/Materials” and “Materials & Metals.” Of the 12 awards in these two categories, three caught my eye: A new method (The Armstrong Process) for producing titanium powder on a continuous basis, with significant cost reduction (International Titanium Powder, Inc., www.itponline.com) A glass-forming overlay steel welding wire that does not require a metal binder phase, with superior properties and a price advantage over carbide wire in shielded and open arc applications (The NanoSteel Co. Inc., www.nanosteelco.com). Nickel aluminide intermetallic furnace rolls exhibiting superior yield strength, creep-rupture strength, and oxidation resistance compared with conventional austenitic stainless steel hot rolls (Duraloy Technologies Inc., www.duraloy.com). It is encouraging to note that the national laboratories continue to play an important role in the development of these new innovative processes and materials, in cooperation with industry—reflecting a wise allocation of tax dollars. Rewind to the evening of Tuesday, May 15, 2007. On that occasion, PowderMet2007 registrants participating in the conference social event attended a seemingly innocuous baseball game at Coors Field in Denver between the Colorado Rockies and the Arizona Diamondbacks. Who would have predicted that these two teams would battle for the National League Championship? I have a hunch that the Rockies season turned around when our very own Jean Lynn, enjoying a rare moment of stardom, caught a vicious foul ball!
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Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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Photo Ronnie Nilsson
You buy more than metal powder – you buy knowledge!
NAH 2004/04
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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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NEWSMAKER
ALEXANDER LITVINTSEV By Peter K. Johnson* Alexander Ivanovich Litvintsev, general director of Alspors Technology Ltd., Moscow, known for his work on aluminum powder metallurgy (PM), grew up in a scientific atmosphere. Born in Vladivostok, in the Far East region of Russia, he spent his early years in Aleksandrovsk-Sakhalinskiy, a small city on Sakhalin Island in the Sea of Japan. His father, a chemical engineer, managed the municipal chemistry laboratory there. In 1947, at the age of 18, he left home to attend the Moscow Railway Institute on a scholarship with lodging in a student hostel. “My main goal was to become a scientist,” he says. “I loved physics and chemistry. My father and mother wanted me to study in Moscow.” Having completed three years at the Railway Institute, Litvintsev hoped for a transfer to the Moscow Institute of Steel and Alloys to study at the new physical chemistry facility. However, rigid government regulations made this a difficult move. He was accepted initially for the 3rd course of the technological faculty. During the first semester in 1950 he completed all his examinations and was admitted to the 3rd course of the physical chemistry faculty. This resulted in the loss of his scholarship and residency in a student hostel. “My parents helped me to pay my living expenses for food and a rented room,” he says. The main condition of his move to the Moscow Institute of Steel and Alloys was achieving a first-class category in skiing. His athletic skills finally won over the institute’s director when he achieved a Master of Sport (first-class category) in skiing in 1949. He graduated from the institute with honors in 1954, receiving the equivalent of an MS in the physics of metals. Postgraduate studies on the Xray diffraction and electron microscopy of metals
followed. His interest in PM developed under the guidance of Professor Y. S. Umansky. Litvintsev received a PhD in 1958, concentrating on hightemperature tungsten carbide and titanium carbide. The title of his thesis was, “The Study of a Debye Characteristic Temperature for TiC-Based Carbides with Refractory Metals, Cr, Mo, and W.” After completing his education, he joined the light alloys plant in Kuntsevo, near Moscow, as head of the Xray laboratory. The plant was the first in Russia, he claims, that began producing hightemperature SAP (sintered aluminum powder) material.** “In 1958 I developed a method of mass spectrometric analysis of the kinetics of degassing aluminum powders during heating up to 600°C (1,112°F) in a vacuum and in argon,” he says. “Subsequently I developed a theory for aluminum powder degassing and an experimental process for degassing and producing semi-finished SAP products.” In 1961 he transferred to a branch of the AllUnion Institute of Aviation Materials at the Kuibyshev metallurgical plant. Using his degassing process, he designed a new technology for degassing cold-compacted aluminum powders in reusable cans in inert-gas flow. These results led to the commercial production of hot-extruded semi-finished products via the direct extrusion of aluminum PM alloys. During this time his interest in PM blossomed. He specialized in developing new PM aluminum materials such as high-strength, high-silicon alloys, metal matrix composites (MMC), and production processes. He recognizes the scientific guidance of academician I.N. Fridlaynder in this work. “Using X-ray methods I studied the processes of aluminum powder oxida-
*Managing editor and consultant ijpm **SAP, a fine dispersion of aluminum oxide in an aluminum matrix, was developed by researchers in Switzerland during the 1940s.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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NEWSMAKER: ALEXANDER LITVINTSEV
tion and examined the phase composition of oxide films of various aluminum base melts,” he says. Litvintsev’s next career step was joining the Kuibyshev Polytechnic Institute in 1970 as assistant professor in the general physics department where he taught physics and materials science. He stayed there two years until returning to Moscow as deputy head of the aluminum powder laboratory and head of the aluminum powder section of the All-Union Institute of Light Alloys (VILS). “I concentrated on the development of technological processes for manufacturing semi-finished products from SAP alloys,” he says. “We used VILS pilot plant equipment: horizontal hydraulic presses and hydraulic cold compacting.” His work opened the way to make SAP bars and shapes for nuclear applications as well as sheet, strip, and bar for the aviation industry. “I paid special attention to developing a process for producing thinwalled SAP tubing including capillary tubes. I also developed a magnetic separation process for aluminum powders at one of the Ural powder shops.” His magnetic separation method led to the Russian standard for aluminum powders (1009676). Some additional accomplishments while working for VILS included the development of various aluminum alloys with zinc, copper, and magnesium, and an aluminum–silicon system for extruding semi-finished products and forged pistons for a tank engine. In 1991 he left VILS because of a management disagreement and formed his own company, Alspors Technology Ltd., to manufacture aluminum PM products. He collaborated with the joint stock company Nadvoitsky Aluminum Smelter in Korelia to make PM aluminum oil-pump bearings and a diesel engine camshaft support.
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His company produced 600,000 parts in 1994. “This was the first large-scale production of aluminum PM parts in Russia,” he notes. Leveraging his experience in manufacturing aluminum PM products, he developed a new process for making hot-extruded flat strip for the subsequent rolling of foamable precursors. He received a Russian patent (RU 2121904) for “A Method for Production of Porous Semiproducts from Aluminum Alloy Powder” in 1998. The method was based on the direct extrusion of an aluminum powder mixture with TiH2, a foaming agent. In this process he combined hot compaction and hot extrusion of the mixture of aluminum powder with TiH2, to make foamable precursors such as sheet, plate, strip, and rod. He received another patent (RU 2200647) in 2001 and a U.S. Patent Application in 2002 for producing foamable precursors via direct powder rolling. This patent opened the way for designing a continuous line for producing precursors via direct powder rolling with clad aluminum, titanium, and stainless steel, and without cladding. Several companies in the U.S. and Europe are interested in his foamed aluminum process. An APMI member for more than 10 years, he has 37 inventions and patents and has authored about 80 scientific papers, as well as one monograph, “Physical and Chemical Background of the Manufacture of Semi-Finished SAP Material.” Litvintsev has received numerous awards and medals for his research and commercial production processes. At the age of 78 he is still not only a creative engineer but an avid sportsman as well, walking 5 to 10 km daily at a steady pace of 6 km/h. ijpm
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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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.”
Miba Sells PM Plant Miba AG, Laakirchen, Austria, has sold its PM parts subsidiary in Barcelona, Spain, Miba Sinter S.A., to Allegra Capital GmbH, Munich, Germany. The purchase price was not disclosed. Market Share Blues Automotive News editors speculated on the further erosion of the Detroit 3’s U.S. market share to well below 50 percent. In July the market share of GM, Ford, and Chrysler slipped to 48.1 percent. PSM Industries Acquires Tungsten Carbide Firm PSM Industries, Inc., Los Angeles, Calif., has purchased Yillik Precision Industries, Inc. (YPI), Ontario, Calif., its fifth acquisition since 2000. YPI makes tungsten carbide PM products such as bushings, bearings, rollers, sizing dies, seal rings, and tooling guides. Chinese Company Buys Metal Flake Technology Nonfermet, Shenzhen, China, will install equipment developed and marketed by Zoz GmbH, Wenden, Germany, to produce nanosize ductile metal flakes in high volumes. Production is expected to begin by the end of 2007.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Domfer Explores Options Domfer Metal Powders Inc., LaSalle, Québec, filed a Notice of Intention with the Office of the Superintendent of Bankruptcy Canada, on August 14. The legal notice, similar to a Chapter 11 filing in the U.S., allows the company to explore various proposals with its creditors. PM Parts Maker Opens Office in Japan Chicago Powdered Metal Products Co., Schiller Park, Ill., has opened an engineering and sales service office in Nagoya, Japan. The office will mainly service North American OEM transplant companies, such as Toyota and Honda, in developing new PM parts applications. Spanish PM Parts Maker Expands Ames S.A., Barcelona, Spain, has opened its fifth powder metallurgy (PM) parts plant in the Aragón region of Spain. The new facility began production in June and is currently producing almost three million parts monthly. Tungsten Company Gains North American Tungsten Corporation Ltd., Vancouver, British Columbia, reported rising sales and earnings for the fiscal third quarter. Production at its Cantung mine increased to 80,357 metric ton units.
Nanofiber Market Surge The international market for nanofibers is forecast to exceed $800 million by 2017, reports BCC Research, Wellesley, Mass. The most important applications of nanofibers are mechanical/ chemical, energy, and electronics. PM Growing in Japan The Japan Powder Metallurgy Association, Tokyo, reports that automotive applications accounted for 92 percent of 2006 PM parts production in Japan. Production increased 4.2 percent to 116,925 short tons, while production of PM bearings declined slightly to 8,776 short tons. Sumitomo Electric Buys Cloyes Europe In a surprise move, Sumitomo Electric Industries, Ltd., and its wholly owned subsidiary Sumitomo Electric Sintered Alloys, Ltd., based in Japan, will acquire Cloyes Europe GmbH. Located in Zittau, Germany, the automotive PM parts operation is owned by Cloyes Gear & Products, Inc., Fort Smith, Ark., and its minority partner, Sumitomo Corporation Group. German Furnace Builder Opens New Business Sarnes ingenieure OHG, Ostfildern, Germany, has stablished SIT Sintertechnik GmbH, in Thale, eastern ijpm
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PM INDUSTRY NEWS IN REVIEW
Germany, to develop sintering technologies. The new company, a partner with PulverMetallurgisches Kompetenz-Centrum, a think tank for PM companies, has sintering and heat-treating capabilities for PM aluminum, PM steel, and metal injection molding. Nanomaterial Earns R&D Award NanoSteel Company, Providence, R.I., has received its third R&D 100 Award from R&D magazine for developing Hardmetal Alternative Technology: Super Hard Steel 9192 Weld Wire. The patented material has a very fine sub-micron microstructure that provides exceptional wear resistance, the company reports. Compacting Press Maker Moves SMS Meer Service Inc., owned by SMS Meer GmbH, Mönchengladbach, Germany, has moved its Pittsburgh office to Cranberry Township, Pa. The company’s broad line of steel products and services includes hydraulic compacting presses. PM Parts Maker Registers Sales Increase Miba AG, Laarkirchen, Austria, reported a four percent sales increase to 196.3 million euros (about $278 million) for the first half of its fiscal year. The company’s Sinter Group (PM parts) generated the largest share of sales at 44.8 percent or 87.9 million euros (about $125 million).
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Industry Leaders Meet PM industry leaders are gathered in Scottsdale, Ariz., for the Metal Powder Industries Federation’s (MPIF) Fall Management Conference and 63rd Annual Meeting. In his address to the delegates, MPIF President Ed Daver discussed the need to grow the global PM marketplace. PM Conference in India The Powder Metallurgy Association of India will sponsor the PM08 International Conference & Exhibition in Chennai, February 20–21, 2008. The technical program committee invites abstracts for oral and poster presentations which must be received by November 15, 2007. New MPIF Officers Mark C. Paullin, president and CEO of Capstan, Torrance, Calif., officially began serving a two-year term as president of the Metal Powder Industries Federation at the close of MPIF’s 63rd Annual Meeting in Scottsdale, Ariz. William A. Heath, PMT, vice president– marketing & business development, Metal Powder Products Corp., Westfield, Ind., began a two-year term as president of the Powder Metallurgy Parts Association. PM Design Competition Opens MPIF has opened the 2008 International PM Design Excellence Awards Competition, which recognizes outstanding achievements in the commercial production of powder metallurgy components. Entries must be received by January 31, 2008.
Hoeganaes Expands Annealing Capacity at Romanian Plant Hoeganaes Corporation, Cinnaminson, N.J., will install a second continuous annealing furnace at its Buz˘au, Romania, iron powder atomization plant. Scheduled to be operating in the second quarter of 2008, the furnace expansion follows the recent installation of a 20-ton blending unit. United States Bronze Powders Opens Distribution Center United States Bronze Powders, Inc., Flemington, N.J., has opened a distribution warehouse for the western Pennsylvania PM market at Jet Metals, Inc., in St. Marys. Jet Metals will stock all powder grades previously held at another location. MIM Business Growing Worldwide The Metal Injection Molding Association estimates that the international metal injection molding (MIM) parts market surged more than 25 percent in 2006 to about $550 million. MIM markets in Europe and Asia experienced the most growth. Arburg Opens Midwest Technology Center Arburg GmbH + Co KG, Lossburg, Germany, has opened a new technology center in Elgin, Ill., about 30 minutes from O’Hare International Airport. The company reports making a significant investment to serve its growing customer base in the Midwest. ijpm
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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SPOTLIGHT ON ...
MARYANN WRIGHT Education: Siena College, BS Chemistry, 1979 Rensselaer Polytechnic Institute, MS Materials Engineering, 1982 Why did you study powder metallurgy/particulate materials? My introduction to powder metallurgy (PM) occurred in the first job after graduating from college. I was working as a chemist at Homogeneous Metals (HMI), a nickel-base superalloy powder producer. Subsequently, I took an introductory course in metallurgy at a local community college, and found the subject matter of sufficient interest that I applied to RPI’s master’s degree program in Materials Engineering, and was accepted. After obtaining my graduate degree from RPI, my career path tur ned to Materials Engineering. When did your interest in engineering/science begin? I have had an interest in chemistry, physics, and biology since I was in elementary school, and this interest continued through high school and college. I was considering a career in the health professions, but, after my first real job at HMI, I became hooked on materials engineering. What was your first job in PM? What did you do? In my first job at a PM company (HMI) I worked as an analytical chemist and trained as a process engineer. After graduate school, I worked as a powder metallurgist at Remington Arms Company on their metal and ceramic injection molding program. My first responsibilities included characterizing raw materials and assisting our suppliers in developing material specifications for metal injection molding (MIM). I also worked in the area of metal and ceramic injection molding feedstock development, together with scientists at DuPont.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Describe your career path, companies worked for, and responsibilities. I have been with the Powder Metal Products Division (PMPD) of Remington Arms Company for approximately 25 years. I started as a materials engineer and, through the years, remained with the MIM program from the early phases of development to where it is now. During my career in PMPD, I have worked in the areas of materials characterization, debinding and sintering, and many other aspects of MIM processing and component qualification. I currently work as the engineering supervisor of the division. What gives you the most satisfaction in your career? I find the equipment and process troubleshooting aspects of my job to be challenging and rewarding. I also enjoy working with our commercial customers on a variety of MIM applications. I am still learning about this process, even after 25 years. So, I like the continuing challenges and learning opportunities that my job provides. List your MPIF/APMI activities. Currently, I am a member of the Program Committee for the upcoming PM2008 World Congress, I also participate as a member of the Editorial Review Committee of the International Journal of Powder Metallurgy. What major changes/trend(s) in the PM industry have you seen? Because I have been in the MIM and PM industries for a number of years, I have been privileged to witness Engineering Supervisor Powder Metal Products Division Remington Arms Company 14 Hoefler Avenue Ilion, New York 13357 Telephone: (315) 895-3516 Fax: (315) 895-3227 E-mail:
[email protected]
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SPOTLIGHT ON ...MARYANN WRIGHT
THE WORLDWIDE LEADER IN GRAPHITE AND CARBON POWDER FOR THE POWDERED METAL INDUSTRY
Enhance Your Powdered Metal Parts And Mixtures With Asbury Graphite NATURAL GRAPHITE
their growth, and, in particular, the MIM industry, from a fledgling technology to a viable, soughtafter metals manufacturing process. I have seen expansion of the applications for both technologies, and acceptance of the technologies, and the consolidation and assimilation of small parts producers into larger companies. Why did you choose to pursue PMT certification? I chose to use certification as a vehicle for training engineers and technicians new to PM and MIM, and, in the process, decided to obtain certification myself. I believe that having professional certification that is recognized by the industry demonstrates a high level of competency to colleagues and customers. For me, it was not only a training tool but also a marketing and career development tool. How have you benefited from PMT certification in your career? Certification helps to convince customers that they are working with an experienced, knowledgeable technical staff member. All of the engineers in PMPD have obtained their PMT Level I certification.
SYNTHETIC GRAPHITE GRAPHITE LUBRICANTS
What are your current interests, hobbies, and activities outside of work? I train at the gym, am active with a local running club, and practice yoga. I just completed my first Boilermaker 15K Road Race in Utica, New York. My husband, Michael, and I are in the process of renovating our summer home, and also spend time with our Little Brother, Nick, through the Big Brothers, Big Sisters Program. ijpm
ISO 9001 - 2000 CERTIFIED
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PM METALLOGRAPHY COMPETITION
WINNING ENTRIES: 2007 APMI INTERNATIONAL PM METALLOGRAPHY COMPETITION, PART II RESEARCH & DEVELOPMENT 1st Place Bruce Lindsley & Gerard J. Golin Hoeganaes Corporation Cinnaminson, New Jersey
Introduction: Graphite, copper, and nickel are the most commonly used additives in ferrous PM. They are added to the base iron or low-alloy steel powders to enhance physical and mechanical properties. Their behavior and benefits are well known and reasonably well understood, but their effect on the pore structure remains more of a mystery. To shed light on this situation, an automated image analysis study was undertaken to help explain the effects of the individual additives and some of their interactions on the pore network.
graphite, 2 w/o Cu or 2 w/o Ni, 2 w/o Cu and 2 w/o Ni, and were copper free or nickel free. In all, eight compositions were selected for testing. The bars were prepared using standard metallographic techniques, backfilled with epoxy using vacuum impregnation, and re-prepared using optimal grinding and polishing practices. This preparation sequence was used to ensure the most faithful appearance of the pore structure. The samples were then analyzed using an automated image analysis system where pore sizes and shapes were measured and calculated. A total area of 4.86 mm2 was examined on each sample at a resolution of 0.36 mm/pixel. In looking at the individual pores, the total population was separated into two groups; small pores <6 mm in maximum length, and all pores >6 mm. The shape analysis is the reason for the split by size because measuring shape on the smallest features skews the distribution toward higher values, thus giving misleading information on the sintering response of the material.
Experimental Procedure: A set of experiments was performed to compare the physical and mechanical properties of FL-4400 (prealloyed 0.85 w/o Mo) base powder with various additions of graphite, copper, and nickel. Transverse rupture (TR) bars were pressed at 690 MPa (50 tsi) and sintered at 1,120°C for 15 min at temperature in a 90 v/o nitrogen/10 v/o hydrogen atmosphere. Sintered densities ranged from 7.05 to 7.09 g/cm3 for the copper-containing materials and 7.09 to 7.18 g/cm3 for the copper-free materials. From these experiments, broken TR bars were selected for metallographic characterization of the pore structure. The bars contained 0.6 or 0.9 w/o
Results: Numbers of pores and the size and shape distributions were measured on each sample. Figure 1 shows the location of the copper particles and the areas where large pores will be located after the melting of the copper. The numbers of pores by mix composition and size group are shown in Figure 2. The 2 w/o Cu/0 w/o Ni samples clearly show a reduction in the total number of pores, especially in the number of pores in the small category. The other three groups show similar results. The number of large pores, defined as features >2,000 mm2 in area, are shown in Figure 3. All copper-containing samples show a large number of the countable pores
THE EFFECT OF ALLOYING ADDITIVES ON PORE MORPHOLOGY—A QUANTITATIVE STUDY
Presented at PowderMet2007 in Denver, Colorado. Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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PM METALLOGRAPHY COMPETITION
with a range of 17 to 22 in the total test area. The copper-free samples showed significantly fewer large pores, five or less for all four compositions. Figures 4 and 5 show the size and shape distribu-
tions using the results from the 0.6 w/o graphite samples. One graphite content is displayed in each case because of the similarity in results to the higher carbon level. In Figure 4, the size distribution for the copper-containing mixes show the presence of larger pores compared with the copper-free materials. The graph is a cumulative plot of the total area occupied by pores of a given size. Therefore, the copper-containing materials show pores >4,000 mm2 while the largest area in the copper -free bars was <3,000 mm 2. Shape analysis (Figure 5) is a cumulative percent plot of the shape measured using the expression 4πA/P2. The value for this expression increases with a smoothing of the pore surface, to a maximum of 1 for a circular shape. Three of the curves are similar with the orange curve, the 2 w/o Cu/0 w/o Ni
Figure 1. Low-temperature-sintered 2 w/o Cu material. Areas occupied by copper particles will be large pores upon melting
Figure 4. Pore-size analysis shown as cumulative percent area occupied
Figure 2. Number of pores separated into large and small sizes
Figure 3. Number of large pores by area (>2,000 mm2)
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Figure 5. Pore-shape analysis. Curves toward the right indicate smoother, rounder pores
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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PM METALLOGRAPHY COMPETITION
(a)
(b)
Figure 6. Backscattered electron images: (a) alloying of copper, (b) copper–nickel. Bright regions indicate the presence of higher atomic number elements. In (a), copper is seen as thin areas between particles or blocky areas filling small pores. In (b), copper appears primarily in large concentrated regions
sample, shifted to the right, indicative of smoother pore surfaces. Discussion: Little difference was seen when comparing the copper-free materials in all categories measured. This is probably due to the fact that all diffusion occurs in the solid state. The two copper-containing materials were similar in relation to the number of large pores and the overall size distribution because of the particle size of the copper powder and the open space remaining as the copper particles melt. However, the total number of pores, both large and small, and the shape distribution show distinct differences. The number of small pores in Figure 2 is reduced by as much as 40% when comparing the copper– graphite sample with the copper–nickel–graphite, and the copper-free samples. A smaller reduction is seen in the larger pores shown in Figure 2, namely 10%–15%. Additionally, a major difference in pore shape is seen in the copper–graphite samples compared with the other three sets. A smoothing of the pore surfaces is seen due to the
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
liquid copper traveling along the particle surfaces (pore edges) and filling in asperities and small pores. This is not the case in the copper–nickel sample where the liquid copper runs along the boundaries until it encounters an area rich in nickel and alloying occurs with the nickel and copper (Figure 6). Alloying prevents the flow of copper along the pores, and therefore the loss in the pore numbers and the smoothing of the pore edges is not seen. Summary: Graphite and nickel appear to have similar effects on the size and shape of the pore structure due to solid state diffusion during sintering. However, the presence of liquid copper during sintering has a major effect on the number of large pores, and on the pore size distribution in all the copper-containing materials. The presence of nickel appears to interfere with the distribution of liquid copper and, consequently, reduces the effect on the reduction in the number of pores and the pore shape.
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RESEARCH & DEVELOPMENT 2nd Place Louis G. Campbell Metallurgical Engineer Eaton Electrical 200 Westinghouse Circle Horseheads, New York 14845 GRAVITATIONAL EFFECTS ON LIQUID-PHASE MICROSTRUCTURES IN TUNGSTEN– NICKEL–IRON
93 w/o W/NiFe: Microgravity sintered 120 min at 1,500°C. Slip lines in liquid phase
SAMPLES: 35 w/o W/NiFe, 78 w/o W/NiFe, and 93 w/o W/NiFe alloys with 7:3 Ni:Fe weight ratio Liquid-phase sintered at 1,500°C for varying times under vacuum in orbital microgravity and on Earth PREPARATION: Section with precision wafering saw (Struers Accutom-5, alumina blade)
78 w/o W/NiFe: Earth sintered 180 min at 1,500°C. Slip lines in liquid phase
35 w/o W/NiFe: Earth sintered 180 min at 1,500°C. Slip lines in liquid phase. Anisotropy of indent on grain boundary 35 w/o W/NiFe: Microgravity sintered 600 min at 1,500°C. Immersion etched 90 s with 60 mL methanol, 15 mL HCI, 5 g FeCl3
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Hot compression mount, transparent acrylic (Struers Specifast) Wet hand grind, 320 grit SiC paper to unmask/ plane Wet hand grind, 600 grit equivalent Trizact (Leco Corp) Autopolish (Struers RotoPol-4 using Struers cloths): 9 µm polycrystalline diamond, MD-Plan, 2 min, 25N/sample 9 µm polycrystalline diamond, MD-Dac, 2 min, 25N/sample
35 w/o W/NiFe: Ground sintered 600 min at 1,500°C. Immersion etched 90 s with 60 mL methanol 15 mL HCI, 5 g FeCl3
3 µm polycrystalline diamond, MD-Dac, 2 min, 25N/sample 0.04 µm silica (Struers OP-S), MD-Chem, 4-6 min, 25N (only samples not used for hardness testing) HARDNESS TESTING: 10 kgf Vickers (Leco V-100C) Diagonal lengths by image analysis
35 w/o W/NiFe: Microgravity sintered 600 min, 1,500°C. Immersion etched 90 s with 60 mL methanol, 15 mL HCI, 5 g FeCl3
35 w/o W/NiFe: Earth sintered 180 min at 1,500°C 180 min at 1,500°C
35 w/o W/NiFe: Microgravity sintered. 180 min at 1,500°C
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35 w/o W/NiFe: Earth sintered 180 min at 1,500°C. Vickers hardness indents
35 w/o W/NiFe: Microgravity sintered 180 min at 1,500°C. Vickers hardness indents
During a study of the effects of gravity on the mechanical properties of liquid-phase sintered tungsten–nickel–iron alloys, the hardness of the segregated liquid phase in 35 w/o W/NiFe sintered in the Earth’s gravity was found to be significantly higher than either the settled tungsten-grain region of the same sample, or the sample sintered in microgravity with evenly dispersed tungsten grains. The increase in hardness in the settled region can be explained by the higher contiguity of the settled region formed by gravity. The increase in hardness in the segregated liquid-phase region could not be explained by tungsten continuity. Examination of the hardness indents revealed slip lines generated by the indents in the liquid phase for all three alloy compositions studied. The slip line pattern, plus anisotropy, on a hardness indent near a matrix grain boundary away from the gravitationally settled region, indicated a difference in grain-to-grain liquid-phase properties. Etching revealed a lamellar microstructure in the Earth-sintered 35 w/o W/NiFe liquid phase, away from the settled-grain region. Identical etching of microgravity sintered 35 w/o W/NiFe found
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little occurrence of the lamellar structure. SEM/EDS of the etched Eearth-sintered liquid phase found smooth grains free of lamellae, typically bordered by tungsten precipitates or near tungsten grains, as well as the tungsten-rich lamellar regions. The smooth matrix microstructures were formed by heterogeneous nucleation during solidification, and the harder lamellar region was for med by homogeneous nucleation in the absence of heterogeneous sites such as tungsten grains or high-angle grain boundaries. The even distribution of tungsten grains in the microgravity-sintered sample prevents formation of these lamellar matrix microstructures, resulting in a lower hardness in the matrix phase.
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RESEARCH & DEVELOPMENT 3rd Place Professor Carl Blais & Maude Larouche Laval University Department of Mining, Metallurgical and Materials Engineering 1728 Pavillon Adrien-Pouliot Québec G1K 7P4 Canada
TABLE I. COMPOSITION OF MIXES
Mix A Mix B Mix C
C (w/o)
Si (w/o)
Cr (w/o)
Nb (w/o)
Fe (w/o)
4.5 4.5 4.5
3.0 3.0 3.0
30.0 30.0 30.0
-----5.0 10.0
Bal. Bal. Bal.
IRON-BASE WEAR-RESISTANT COATINGS WITH CHROMIUM CARBIDES VIA LIQUIDPHASE REACTIVE SINTERING INTRODUCTION Hardfacing refers to the deposition of hard, wear-resistant coatings on the surface of a component using welding processes (FCAW, SMAW, SAW).1 The attendant surface modification leads to reduced loss of material by erosion, abrasion, impact, etc. Nevertheless, many alloys containing chromium carbides check-crack during cooling. Such cracks are the result of high stresses induced by the contraction of weld metal as it cools. They typically propagate through the thickness of the weld bead and generally stop at the parent metal, provided it is not brittle. The presence of a high density of cracks leads to premature degradation of wear resistance. METHODOLOGY Table I presents the composition of the three different alloys studied. Niobium was added to mixes 2 and 3 in the hope that it could pin the primary chromium carbides in order to minimize their growth and retain their mean diameter under 50 µm. The chemistries presented in Table 1 were obtained using different amounts of powders of ferrochromium, ferroniobium, ferrosilicon, graphite, and iron. Samples were pressed using transverse rupture (TR) tooling to obtain bars with a density equivalent to 90% of the pore-free level of the alloy, and a thickness of 5 mm. Sintering was carried out in a tube furnace at a temperature of 1,225°C for 1 h under an atmosphere of argon. Each sintering test consisted of placing two TR bars from the same mix on an 18-gage sheet of low carbon steel (AISI/SAE 1005). A 5 mm space was initially left between the two TR bars prior to sintering. Figure 1 presents a plan view of the coating after sintering. Note that liquid formation has filled the space between the TR bars so that
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Figure 1. Plan view of coating obtained after sintering. Morphology of the initial TR bars can no longer be distinguished
they can no longer be distinguished. Finally, a series of samples from mix C were quenched after sintering to characterize the effect of rapid cooling on the final hardness of the coating, as well as its propensity to cracking. OBJECTIVE Develop a wear-resistant coating that could be obtained by liquid-phase reactive sintering. Specific goals: • Develop a microstructure consisting of chromium carbides and niobium carbides dispersed in an iron matrix using a water-atomized iron powder and particulate ferroalloys • Control the reactive sintering process to obtain a pore-free microstructure and a carbide size <50 µm • Prevent crack formation upon cooling • Obtain an adherent coating over a substrate of low-carbon steel RESULTS AND DISCUSSION Figure 2 illustrates a cross section (optical microscopy) of a typical coating (mix A). The volume fraction of porosity is small and a small fraction of dendrites is visible. Moreover, the interface between the coating and the substrate is pore
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Figure 2. Optical micrograph of cross section of coating obtained with mix A. (Etchant: Murakami)
free, as highlighted in Figure 3. Figure 4 presents optical micrographs of the typical microstructure of the coating obtained with mix A. It consists of Cr7C3 (colored areas in Figure 4(a)), as characterized by EDS, in a matrix of pearlite (visible as bright areas in Figure 4(b)). Figure 5 presents typical micrographs of the coating obtained with mix B. The wear-resistant layer consists of Cr7C3 (colored areas in Figure 5(a) and 5(b)), a matrix of pearlite (Figure 5(b)), and clusters of small spherical NbC, arrowed in Figure 5(b) and shown at a higher magnification in Figure 5(c). Figure 6 presents typical micrographs of the coating obtained with mix C. These show basically the same microstructure as mix B, namely Cr7C3 in a matrix of fine pearlite with an increased amount of clusters of NbC (Figure 6(a) and 6(c)). Moreover, mix C also contains acicular NbC, highlighted in Figure 6(b) and 6(d). Although Peev2 has shown that such acicular NbC forms when the
Figure 3. Optical micrograph showing the quality of the interface between hard coating (obtained with mix A) and steel substrate. (Etchants: Nital-2 v/o & Murakami)
niobium concentration is larger than 2.5 w/o in white cast iron, our results indicate that, for the conditions studied, the niobium concentration has to be higher than 5 w/o for this phase to form. Finally, a sample was prepared using mix C; it was sintered and quenched in oil. Table II presents the hardness values measured on the top surface of each coating studied. These values
Figure 4. Optical micrographs of coating obtained with mix A showing Cr7C3 formed during liquid-phase reactive sintering, (a) typical microstructure at low magnification; colored areas correspond to Cr7C3, (b) same microstructure as in (a) at higher magnification showing fine colonies of pearlite in matrix. (Etchant: Murakami)
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Figure 5. Optical micrographs of coating obtained with mix B. (a) typical microstructure at low magnification, (b) same microstructure as in (a) at higher magnification showing fine colonies of pearlite in matrix and clusters of NbC (arrow), and (c) high magnification of area arrowed in (b) showing fine NbC. (Etchant: Murakami)
Figure 6. Optical micrographs of coating obtained with mix C. (a) typical microstructure at low magnification, (b) microstructure at higher magnification showing acicular NbC, (c) high magnification of area arrowed in (a) showing fine NbC, and (d) higher-magnification micrograph showing acicular NbC. Etchant: Figures (a) to (c), Murakami, Figure (d), unetched
indicate that there is a small increase in hardness with increasing concentration of niobium in the powder mix. The microstructures show clearly that this effect is directly related to the volume fraction of NbC formed during sintering (compare Figures 5(b) with Figure 6(a)). This is particularly Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
significant since the average size of the Cr 7C 3 (typically 65 µm) does not vary significantly from one mix to the other (compare Figures 4(a), 5(a) and 6(a)). Nevertheless, it seems that quenching has the primary effect on achieving hardness values that fall well within the typical range of hard-
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TABLE II. APPARENT HARDNESS MEASURED ON SAMPLE SURFACE Samples ID
Apparent hardness (HRC)
Mix A : as sintered Mix B : as sintered Mix C : as sintered Mix C : quenched
28 33 39 55
nesses obtained via welding processes (40 to 60 HRC)3. CONCLUSION The main conclusions of this study are summarized as follows: • It is possible to form adherent, pore-free and, most important, crack-free wear -resistant coatings containing Cr7C3 and NbC by liquidphase reactive sintering. • The pining action of the NbC on the primary Cr7C3 does not appear to be effective under the conditions followed in this study. • Although the hardness values obtained are relatively high, it seems that oil quenching cannot be eliminated if hardness values typical of welded coatings are the goal. FUTURE WORK • Characterize the wear resistance of the coatings developed following ASTM standard G35 • Evaluate the possibility of using sinter hardening as a mean of increasing the overall hardness of the coatings REFERENCES 1. ASM, Metals Handbook—Desk Ed., ASM International, Materials Park, OH, USA, 1985, pp. 30–59. 2. K. Peev, Développement de Fontes Blanches à Haut Chrome Contenant du Niobium, MSc Thesis, Université Laval, 1993, pp. 48–68. 3. www.thefabricator.com
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RESEARCH & DEVELOPMENT Honorable Mention Barbara Maroli & Robert Frykholm Höganäs AB Höganäs 263 82 Sweden EFFECT OF NICKEL ADDITION ON MICROSTRUCTURE
When nickel is added to a PM material, the microstructure is affected. In this example, 2 w/o Ni was added to a 0.85 w/o Mo steel with 0.8 w/o graphite. The materials were sintered at 1,120°C for 30 min. The initial structure of essentially randomly mixed coarse and fine bainite was shifted to a fine bainitic structure, with a thin layer of coarse bainite in the border between the base powder and nickel additive. The nickel-rich regions are austenitic or martensitic. Diffusion of nickel is relatively slow and, therefore, steep composition gradients are formed. Even though the diffusion distance for nickel is
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
small, all the material is affected. It can be shown that this is due to thermodynamic coupling between nickel and carbon, and it is an inhomogeneous distribution of carbon that is partly responsible for the microstructure obtained when nickel is added. The graphs show results from calculations on the Fe-Mo-Ni-C system. A constant carbon activity, corresponding to Fe-0.85 w/o Mo-0.8 w/o C, was assumed for each temperature and was used to calculate the equilibrium carbon content in an FCC structure with a nickel gradient. The results show a strong thermodynamic coupling between
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carbon and nickel over the entire temperature range, implying that the nickel gradients formed during sintering create opposite gradients in the carbon. In a real material this means that carbon will diffuse from nickel-rich regions to regions low in nickel. This is observed in the micrographs cited. With nickel additions, there is an increase in carbon content in the interior of the base-powder particles, resulting in fine bainite, while a decrease in carbon on the particle surfaces, due to presence of nickel, gives a coarse bainite. In the other graph, a 20 µm thick layer of nickel between two 100 µm thick layers of Fe-0.8 w/o
C was considered. The system was held at 1,120°C for 30 min, after which it was cooled to 700°C at a rate of 0.8°C/s. The graph shows the short diffusion distance of nickel, and the significant decrease in carbon content coupled with the nickel gradient. The calculations were performed using Thermo-Calc and DICTRA software. In the second (high magnification) micrograph, the results of the calculation are verified experimentally. The variations in microstructure over the border between the nickel addition and the base powder particles clearly confirm the composition gradients. All specimens were etched using picral.
HOT ISOSTATIC PROCESSING SERVICES FOR PRODUCTION AND RESEARCH PROGRAMS ISO 9001, AS9100 REGISTERED
• CASTING DENSIFICATION • Improved Properties • Reduced Rejection Rate • Reduced Scrape Rate
• POWDER CONSOLIDATION • PRESSURE BRAZING • DIFFUSION BONDING • CERAMICS
KITTYHAWK PRODUCTS
11651 MONARCH ST. • GARDEN GROVE, CA 92841 Tel. (714) 895-5024 Fax (714) 893-8709 www.kittyhawkinc.com E-mail:
[email protected]
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PRODUCT/PROCESS CONTROL 2nd Place Rajendra M. Kelkar, PMT Materials Engineer SSI Technologies, Inc. Janesville, Wisconsin D-2 TOOL STEEL OBJECTIVE: To establish a sintering window to achieve “nearly fully dense material” and microstructures for the purpose of process control of this alloy. PROCESS: Ring samples were pressed to 6.3 g/cm3 green density. A vacuum furnace with a partial pressure of nitrogen was used to sinter all the samples with a 45 min hold time.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
OBSERVATIONS: As sintering temperature increases, grain and carbide coarsening is evident. Rapid densification is observed over a narrow temperature range of 1,232°C–1,238°C (2,250°F–2,260°F), which is normal in liquid-phase sintering alloys. Microstructures at 1,227°C, 1,238°C, and 1,246°C (2,240°F, 2,260°F, and 2,275°F) are undersintered, “nearly fully dense,” and oversintered, respectively. A density drop of 0.9 g/cm3 can be observed at 1,246°C (2,275°F) compared with 1,238°C (2,260°F). This is explained by the pore and carbide formation and growth at the grain boundaries. A continuous grain-boundary carbide network can be seen in the microstructure sintered at 1,246°C (2,275°F).
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ARTISTIC 1st Place CREEPY CRAWLIES Christopher T. Schade Manager–Pilot Plants Hoeganaes Corporation Cinnaminson, New Jersey
ARTISTIC 2nd Place FEATHERS Gerard J. Golin Metallographer Hoeganaes Corporation Cinnaminson, New Jersey
ARTISTIC 3rd Place Bruce Lindsley Manager of Product Development Hoeganaes Corporation Cinnaminson, New Jersey
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OUTSTANDING POSTER AWARDS
Presented at PowderMet2007 in Denver, Colorado. Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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CONSULTANTS’ CORNER
JOSEPH TUNICK STRAUSS* Q
We make powder by inert-gas atomization. Sometimes the powder appears “sticky” in that it does not flow well, or even appears to clump together. What could be the cause? There are many potential causes of this problem, some of them alloy dependent, and others related to the process. I will try to address this question to cover most of the obvious causes. In addition, your question includes the word “sometimes,” which implies that most times the powder is not sticky and flows properly. This means that you have some condition that is changing over time, perhaps by the run or maybe even seasonally. “Stickiness” is indicative of particle-to-particle interactions that impact the bulk flow of the powder. This interaction could be from interparticle friction, actual metallic bonding between particles, or electrostatic attraction. 1) Particle-Size Distribution and Morphology: In general, the wider the particle-size distribution, the better the powder packs, which leads to more difficulty in flowing. An excessive amount of fines (material <10 µm) in a wide distribution will definitely slow things up with respect to flow due to packing and interparticle friction. Have you checked the powder, either by screen analysis or by laser diffraction methods? Has your atomization process been producing more fines in the runs that are problematic? The flow properties of the powder will also change as the powder particle morphology deviates from sphericity. Most inert-gas atomizers produce relatively spherical powder. However, satellites essentially make the powder irregular in shape and the powder will not flow as well. Satellite formation is the result of impact between particles before solidification is complete. Usually this occurs when the powder-laden environment inside the atomization chamber is entrained into the
A
plume of newly forming droplets. Vessel pressure and total gas flux within the vessel will influence the formation of satellites and the problem is amplified by higher pouring temperatures and higher melt flow rates. Again, has anything changed with respect to these two parameters for the runs that yielded “sticky” powder? Satelliting is easy to evaluate by microscopy. 2) Particle Bonding: Particles can bond metallurgically to each other resulting in “sticky” powder. Particles can tack sinter, spot sinter, or weld at their contact points. This phenomenon is not as severe as satelliting in that this bonding can be somewhat reversed by mechanical forces (sieving or mechanical agitation is usually sufficient). Tack sintering occurs when the particles contact each other while at temperatures high enough to allow for metallurgical bonding. This can occur during atomization or, more likely, while the powder accumulates in the collection canister of the vessel. This problem is exacerbated by an increase in fines. Has the operating temperature of the atomization system increased due to higher melt temperatures, increased melt flow rates, or decreased gas flow rates? Does your atomizer use a secondary source of cooling gas? If so, is this system operating correctly? Tack sintering is also amplified when the powder surface is extremely clean. Most atomization systems operate with a finite pressure of oxygen, either from the atomization-gas source or from inherent leakage in the equipment. This oxygen combines with the alloy to form a thin film of oxide on the particle surfaces and prevents tack sintering. A reduction in the background-oxygen content of the system, or changes in a oxygen-sensitive
*Engineer/President, HJE Company, Inc., 820 Quaker Road, Queensbury, New York 12804, Phone: 518-792-8733; Fax: 518-792-8735; E-mail:
[email protected]
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alloy component (silicon, manganese, phosphorus, boron, etc.), could be likely causes. Tack sintering may not be apparent by microscopy. 3) Moisture Content: Sometimes moisture in the powder will reduce flowability and make the powder feel “sticky.” Moisture can come from the ambient atmosphere or from a leaky atomizer chamber (if the chamber is water cooled). In some cases, if the powder is brought to sub-ambient temperature (via cold cooling gas or water-cooled chambers) and then exposed to the ambient atmosphere while still cold, then moisture can condense on it. Stickiness due to moisture is usually reversible once the powder dries out, unless it causes oxidation of the powder, which results in an entirely different problem. In any event, the fresh powder can be evaluated for the presence of moisture by a weight-loss test. This works best for powder that does not readily oxidize. Copper, tin, and zinc, among others, may show a weight gain during heating due to oxidation so this test is not foolproof. Moisture problems can be seasonal with more problems occurring in the spring and summer when moisture levels are high. 4) Static Charges: Static charging, to the extent that it affects the bulk powder, is rare in metallic powder systems but it can still happen. Usually it manifests itself as powder attraction within the bulk and also to containers, especially those that are not grounded. All atomization systems, chambers, transfer lines, and collection vessels should be well grounded regardless of the alloy system. It is imperative for pyrophoric powders such as aluminum, magnesium, and titanium. In this case, some moisture in the ambient atmosphere can reduce the static problem. Static problems can be seasonal and more prevalent in dry months (winter).
Q
There is much press, frequent technical workshops, and significant government funding focused on nanomaterials. Are the claims of earth-shattering breakthroughs really true? What are the caveats and known limitations for a PM company considering developing products in this area? What are the current applications for nanopowders? Will nanopowders ever be used for structural parts? When people ask me if they should invest in “nano” materials I tell them that investing in “nano” is as ambiguous as investing in the color
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red. There are just too many areas covered by the term “nano” and picking the right one is a crapshoot. With the risk of further insulting the nano community, it is my judgment that, “nano” has been hyped out of proportion by commercial operators, national laboratories, academic institutions, and their associated marketing machines. There are nanomaterials, nanostructures, nanomachinery, nanobiology, nanoelectronics, etc. Trying to figure out what is really new and what has potential is obscured by the use of the term “nano” while describing traditional materials and processes; or worse, in describing things that are not nano at all. For example, filled plastics have been around for over 50 years and have used fumed silica, carbon black, and natural clays as the fillers, all of which are nanopowders. But now filled plastics fall under the term “nanocomposites” and R&D efforts appear to be investigating the “same old.” Cosmetics, sunscreens, and paints now flaunt “nano” additives, which are nothing more than the same old zinc oxide, titania, and other synthesized or ground pigments. But now that environmentalists are on the bandwagon flaunting the potential new dangers of nanomaterials it is interesting to note that those using the “nano” term in FDA-sanctioned products are backpedaling. The confusion and concern within the PM community is that our mindset hears “nano” and immediately considers nanoparticulates, which is only one small segment of the “nano” world. We work with powders of a finite particle size generally >1 µm and nano to us means finer powders— much finer. Nano, in strict terms, refers to entities of one billionth of a meter (10-9 m), which is on the order of atomic clusters and molecules (thus organic chemistry and molecular synthesis have always involved nanoprocesses). Based on ASTM Standard E2456-06, metallurgists have extended the nano term a few orders of magnitude up to the submicron scale, a relatively large regime. When reviewing information containing the term “nano” it is important to understand that nanoparticulate, nanocrystalline, and nanostructure are entirely different terms. A nanoparticulate material is a powder whose individual entities (particles) are sized in the nano regime (10-9 m to 10-6 m). Nanocrystalline materials are materials: powder, bulk, coatings, etc., whose grain size is in the nano regime. Nanostructures can be any entity in the material, such as precipitates, dislocation
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cells, surfaces, even pores, that have a size scale in the nano regime. Heavily cold-worked material that goes through a heat treatment to recrystallize first passes through a nanocrystalline phase before grain growth yields micron-sized grains that are most common in conventional mill products. Nanostructures have been around for longer than we have fully understood them: Guinier-Preston zones (and what they evolve into), the nanosized structures responsible for precipitation hardening, were named in 1938 although they were surmised to exist almost 20 years earlier (Meica, Waltenberg, and Scott, 1919). Many other hardening mechanisms in metals, such as substitutional strengthening and strain hardening that invovle impeding dislocation motion, are based on entities on the nanostructure size scale and always have been. Dislocation cell structures that result from high levels of plastic deformation are nanoscaled structures. Pearlitic and bainitic structures in steels have spacings that are in the nanoscale regime. Redefining these traditional entities under the term “nano” does not make them new or different. One of the aspects that confuse the “nano” term with respect to PM is the “bait and switch” practice used by some researchers. They start by measuring the powder particle size in terms of microns (usually by Microtrac or some other device using laser diffraction). This “macro” powder is subjected to a high-energy process (milling, plastic deformation, etc.). The processed powder is then examined by TEM or X-ray diffraction to show the existence of a nanostructure. Finally, the size of the nanostructure is compared with that of the initial powder particle size to show the effect of the process in producing nanopowders. This is absolutely incorrect. Certainly a milling or deformation process is capable of reducing the particle size of the powder but reporting the size of an internal nanostructure is not the same as the powder particle size per se. Referring to nanoparticulates, which I think was the way this question was directed, we have all heard the accolades afforded nanopowders in PM: much lower sintering temperatures while yielding high densities and with strengths and ductility greater than conventional materials. From first principles this is all possible. The driving force for sintering increases with decreasing particle size, thus nanosized powders will sinter at lower temperatures with respect to the same alloy whose
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
particles are in the micron-scale regime. The HallPetch relationship certainly verifies that yield strength increases with decreasing grain size (assuming that the grain size of the material that starts off as a nanopowder remains smaller than that of conventional PM materials). The fine grain size may enable superplastic properties. But what about creep strength? Resistance to creep is decreased with a smaller grain size; but no one seems to address this when extolling the advantages of “nano” materials. The PM community is overwhelmingly based and focused on metals. PM also applies to ceramic and other covalent materials made from powder, but this is a minor application of PM. So, where are we with metal nanopowders? I have addressed this in previous Consultants’ Corners as to their availability and applicability to PM. To summarize: 1) Nanopowders of metals (specifically iron) are only available in vacuo as they are made. Until a way to transport and handle nanopowders without spontaneous exother mical events results in nanocovalent powders (oxides), they will remain largely uncommercialized. There are nanopowder systems that produce metal nanopowders but subsequent consolidation and sintering are performed within the system to eliminate exposure to the atmosphere. These systems are capable of production rates ~g/day. Nanosized iron and nickel powders can be produced by the traditional carbonyl method, but at the upper range of the nanoscale (submicron) regime. Nanosized powders of other metals (such as refractory metals and precious metals) have been available for decades and are made by chemical reduction or precipitation, electrochemical methods, and gas reaction methods. In all cases the powder particles are actually stable agglomerates of the nanoparticles. The powder particles do not exist as individual nanoentities. 2) Nanometal powders show some promise but one of the major challenges is keeping the microstructure at the nanoscale. The driving force for grain growth is high so that the consolidated and sintered nanopowders rapidly become materials with micron-sized grains. One must sinter to high density to achieve the ultimate in mechanical properties, but in so doing, grain growth into the microscale appears inevitable. Rapid grain growth causes decoupling of the pores from the grain boundaries, which makes further densification more difficult.
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3) If iron and steel nanopowders were available and handleable, the low tap density would present major challenges in press and tooling strokes, and from powder working its way into clearances between tooling members. 4) MIM of nanopowders presents a special challenge in that the amount of binder needed to accommodate the high surface area would result in an extremely low solids loading. 5) The current cost and availability of metal nanopowders is orders of magnitude removed from compatibility with supply and production in commercial industrial ferrous PM processes. What is the current status of nonmetal nanopowders? To summarize: 1) Nanopowders of ceramic and other covalent materials are readily available and have been, even before the term “nano” applied. However, processes such as sol-gel, hydrothermal, gas reaction, and evaporation/condensation methods allow the synthesis of more materials at higher rates, produced under improved process control than in the past. 2) Cemented Carbides: Submicron carbides have been around for decades and submicron fits in the high end of the metallurgist’s nanoscale. In addition, the synthesis of WC from the reduction of tungstates to tungsten and then carburizing to produce WC is all done at the nanoscale. If one looks at WC (prior to liquid-phase sintering), you do not see discrete micron-sized particles. Rather, WC particles are stable agglomerates of submicron nanosized crystals. 3) Submicron oxides and other ceramics have been processed by press-and-sinter, and by MIM, for years. Ceramists have been processing nanoparticulates for decades on a commercial scale. 4) Dispersion-strengthened alloys (typically ODS or those using ceramic dispersants) depend on nanoscale entities. The availability of more nanoparticulates enables new or enhanced ODS alloys to be made via PM. 5) New applications such as catalytic substrates made from nano zirconia and nano alumina are in production. The powder is processed to provide a permeable bulk material with a high internal specific surface area (>100 m2/g). This material is then coated with a catalyst (nickel, palladium, platinum, etc.) by precipitation or electrochemical methods. At PowderMet2007 there were three sessions devoted to nanomaterials plus nine other nanorelated papers and three nano-related posters.
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There is a lot of “nano” going on with some of it renaming the old and traditional, some new and with exciting potential. The challenge is to separate the wheat from the chaff. Is the term “nano” applied correctly? Is “nano” specific to PM, or is it a natural and common artifact of materials in general? It is time to use some macro critical thinking. So, if you are an engineer in a conventional ferrous press-and-sinter shop and your customers, or your management or marketing staff, are pushing you to do something nano, tell them nano is in the future of PM—and is likely to remain so!
Q A
What are the main heat-transfer mechanisms in sintering and their effects in different furnace types? In general, there are only three heat-transfer mechanisms, whether we are talking about a sintering furnace or the backyard grill. Heat transfer occurs from a hot entity to a cooler one by: (1) conduction, (2) convection, and (3) radiation. Heat transfer is actually the transfer of thermal (kinetic) energy from hot material (rapidly moving atoms or molecules) to cooler material (lower-energy atoms and molecules). Conduction is the transfer of thermal energy by direct contact between the hot and cold entities. Heat transfer occurs through the contacting interface. The rate of heat transfer is generally considered to be proportional to the temperature difference between the two entities. However, the rate is also dependent on the material properties (thermal conductivity), the amount of interface involved in the heat transfer, and the contact efficiency of the interface. Convection is heat transfer between bodies through a fluid (or within a fluid), such as the atmosphere in the furnace. As the temperature of the fluid changes, its density changes with respect to the surrounding furnace atmosphere. This causes gravity-induced flow, which allows continued thermal transfer to, or from, the fluid. To increase the heat-transfer rate, the motion of the fluid can be enhanced by forced circulation. Again, the rate of heat transfer is generally considered to be proportional to the temperature difference between the two entities. However, the rate is also dependent on the material properties of the solid and the fluid (thermal conductivity, heat capacity, and viscosity) and fluid velocity. In general, the more conducting the fluid, and the higher the velocity of the conducting fluid, the greater the Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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NEXT 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: GAYLORD NATIONAL RESORT & CONVENTION CENTER National Harbor on the Potomac
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CONSULTANTS’ CORNER
heat-transfer rate. The fluid can also be a liquid such as the molten salt in a salt bath, which is common in heat-treating applications. Radiation is the heat transfer of thermal energy by photons. All bodies radiate photons whose energy is related to the temperature of the body. The rate of heat transfer is proportional to (Th4Tc4), where Th and Tc are the temperatures of the hot and cold bodies, respectively. The rate of heat transfer is influenced by the emissivities of the bodies, which are essentially the efficiencies with which the bodies radiate and absorb photons (dark rough surfaces have high emissivities, shiny reflective smooth surfaces have low emissivities). Photons do not need a medium such as a gas or solid to travel, thus they can travel through a vacuum. Also, photons do not actually go around corners so heat transfer is considered “line-of-sight.” This means that only the portion of the surfaces in sight of each other can exchange thermal energy. One can see that any type of furnace or heating device will rely on all three heat-transfer mechanisms, but to different degrees. Sintering furnaces are usually either atmosphere furnaces or vacuum furnaces. Atmosphere furnaces can be batch or continuous. High-vacuum furnaces are of the batch configuration. No sintering furnace relies directly on heat transfer through conduction since PM parts do not contact the heating elements. Heat transfer is achieved through convection and radiation. But conduction still plays a part. Sintering furnaces have some form of heating element or hot surface. Heating elements are usually heated by electrical resistance. Fuel-heated furnaces employ the heat of combustion to heat a muffle, which becomes a hot surface, or use heated combusted gases as the heat source to convect directly with the parts (usually kilns for ceramics rather than metallic parts). For most metal-partsintering applications, a muffle is used to contain the parts and the protective or reducing sintering atmosphere. Thermal energy is convected from the hot muffle to the cold parts by circulation of the gas atmosphere. The heating rate is dependent on the magnitude of the gas flow rate. Continuous furnaces generally use much higher rates of gas flow, thus they are able to heat parts more rapidly. Batch furnaces use lower atmosphere flow rates. At low flow rates heat transfer is predominantly by natural convection. Forced convection, and the attendant higher heat-transfer rate, is achieved at higher gas flow rates. Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Higher gas flow rates also produce a more uniform temperature environment in the furnace as the kinetics of heat transfer are higher and thermal equilibrium is approached more rapidly. Forced convection can be achieved by high gas flow rates, or by the use of a fan. Temperature uniformity is generally considered to be optimal in a continuous furnace. This is also a result of the relatively small area cross section of the muffle (measured perpendicular to the direction of movement of the parts). Although convection is greater in a continuous furnace, the high heating rate is also primarily a result of the existence of a preheated muffle. Batch furnaces start cold and the furnace must expend energy and time to bring the furnace and parts up to temperature. Thus, the area under the time–temperature curve can be much greater for a batch vs. a continuous furnace. While it is true that convection is important in atmosphere furnaces, so is radiation heat transfer. Heating elements radiate thermal energy to the muffle, which in turn radiates thermal energy to the parts; thus radiation is essential to heating the muffle and the parts. Heat transfer to the parts is shared by radiation and convection. The exact amount of each mechanism is dependent on the design of the furnace, the atmosphere flux through the furnace, and the operating parameters (heating rate). Continuous furnaces may rely on >50% convective heat transfer, while batch furnaces may rely on >50% radiative heat transfer. Setters and other furnace furniture also play a big part in heat transfer. Ideally they should be made of a material of high emissivity and thermal conductivity. Graphite setters are often used for this reason. But many material applications cannot use graphite and ceramics are used instead. These compromise the heat transfer from conductivity and radiation. This is more of a factor in continuous furnaces where high heating rates are produced. The thermal lag caused by a setter is essentially a temperature gradient. Vacuum furnaces rely primarily on heat transfer by radiation. The higher the vacuum, the greater the contribution to heating by radiation heat transfer. Most vacuum furnaces use a shield around the heating elements. This shield, by virtue of being made from a material with a high thermal conductivity, smoothes out the hot spots produced by the heating elements to provide a more uniform radiating surface to the parts. But the heating is still line-of-sight,
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TRUST must be earned For 90 years, ACuPowder has been delivering the finest quality powders and the most conscientious service. Our customers know that serving their needs and solving their problems is our highest priority. Bring us your toughest assignments. We want to earn your trust, too. The finest powders are from ACuPowder: Copper, Tin, Bronze, Brass, Copper Infiltrant, Bronze Premixes, Antimony, Bismuth, Chromium, Manganese, MnS+, Nickel, Silicon, Graphite and P/M Lubricants.
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which is why placement of the parts is more critical than in other furnaces. Parts can block other parts and setters can also shield parts. In some cases the setters may heat first and then the parts are heated by both radiation from the setter and conduction from the setter. The amount of convective heat transfer is essentially negligible in high vacuum. Once at thermal equilibrium (sintering temperature) the temperature gradients smooth out as all parts, setters, and furnace hardware radiate and absorb equally. It is the time to achieve the equilibrium temperature that produces the temperature gradients. And with temperature gradients there are sintering gradients, which can lead to density and property gradients and distortion in PM parts. In any furnace the objective is to produce an environment with a high degree of temperature and atmosphere uniformity and control. The more heat-transfer mechanisms that are active the greater the temperature uniformity in the furnace. Convection plays a major role in temperature uniformity, which may imply that a continuous furnace is best. However, better atmosphere control is achievable with batch or vacuum furnaces, and some materials require this. Two last items. First, the thermal properties of the part are also important in heat transfer. The green PM part is usually matte and porous and the sintered part can be shiny and dense. This implies that its emissivity is higher and its thermal conductivity lower when in the green state. Thus, the mechanisms of heat transfer within the part change during sintering, which can lead to temperature gradients within the part, especially in large parts. This can contribute to density gradients and distortion. Second, parts subjected to microwave or induction sintering are heated by joule heating. Thermal energy is produced internally in the part by resistive heating. Microwave or induction energy transfer is material dependent. Microwaves are transferred efficiently to a lowdensity green part and can be reflected by a highdensity sintered part. Induction energy couples best with a dense part and may not couple well to a green part. Thus, these two alternative heating methods are also not without challenges. ijpm
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] Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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PERSONAL INSIGHTS
AXEL MADSEN/CPMT SCHOLAR REPORTS PHILIPPE LAPOINTE Laval University Quebec, Canada PowderMet2007 was the first professional conference I ever attended. I have to admit that before the conference, I was slightly nervous and thrilled, considering the importance of the occasion. However, the first few events made me realize there was nothing to be worried about. Indeed, the friendly mind-set surrounding the conference was astonishing. I knew few people attending the conference before my arrival at the convention center, but my advising professor introduced me to his peers. In this way, I had the opportunity to meet some of the pioneers in the PM community. Also, the city in which the convention took place was amazing. Even though Denver stole the Quebec Nordiques, it is still a gorgeous city! The breathtaking view of the natural marvel that the Rocky Mountains constitute, and the cleanliness of the city, are just a few reasons that make Denver so beautiful. I would like to say that I am deeply thankful to the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology for giving me the opportunity to enjoy this rewarding experience. One of the things that impressed me the most about PowderMet2007 was the overall structure of the conference. It started with social events such as the golf tournament and the welcoming reception in order to develop a friendly atmosphere. Then a wide array of technical sessions allowed everyone to find the subjects of primary interest. In my case, many of the sessions were closely related to my thesis project. The sessions on nanoscale powders enlightened me about ways to
produce nanoscale powders and the economic issues related to their use, while the sessions on sintering taught me about new sintering techniques such as microwave sintering. The convenient schedule of the conference allowed everyone to maximize attendance at presentations without having to run from one end of the conference hall to the other. Another surprising aspect of this event was the open-mindedness of everyone. No matter if you were a ”regular” or attending for the first time, no matter where you came from, as long as you spoke English (or tried to!), everyone was pleased to meet one another. It was also a great opportunity for people from academe to meet PM industry practitioners and vice versa. The social activities such as the night at Coors Field certainly enhanced the high level of networking opportunities. In the end, attending PowderMet2007 was a great opportunity for me to improve my knowledge of PM and particulate materials. I hope that eventually I will have the chance to renew this experience. It was a perfect occasion to meet people in the PM industry and colleagues in research, and to create new bonds or just reinforce existing ones. CASEY MCCLIMON Arizona State University Tempe, Arizona Before my advising professor approached me about the CPMT/Axel Madsen Conference Grant, I had only a vague idea about technical conferences. When I found out that I had been selected to attend PowderMet2007 in Denver I was really excited and could not wait to go. With the grant I would be able to experience the full conference,
Axel Madsen/CPMT Grants are awarded to deserving students with a serious interest in PM. The recipients were recognized at the Industry Recognition Luncheon during PowderMet2007.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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including taking part in the poster session. The conference was unforgettable and I would like to share some of my experiences with you. I would like to thank Professor Nik Chawla for nominating me, and the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology for giving me the opportunity to attend. On Sunday I flew to Denver and began my conference experience. The conference was held in downtown Denver which gave visitors the opportunity to experience some of the downtown culture. I stayed at the hotel across the street from the convention center so it was easy to get to and from the conference. Coming from Arizona where there was currently a heat advisory, the cool weather in Denver was literally a breath of fresh air. That evening I attended the welcoming reception, the first social event of the conference. The reception allowed for old and new colleagues to gather and relax with a drink and catch up with each other. There were many people there and I looked forward to meeting some of them. This was my first technical conference and one of my biggest PM experiences. I had little knowledge of the PM industry, aside from the research I had been doing under the guidance of my professor at Arizona State University. I think that the reception would have been a better first experience if I had had someone to shadow and introduce me to people they knew. I enjoy speaking to new people, but no one seemed to want to interact with me. I came to the conference without any of my peers and I felt alone, somewhat rejected and slightly uncomfortable. So I left the reception early and headed back to the hotel to get some sleep and prepare for a full day of sessions. On Monday I attended the opening general session which was my first look into what MPIF and APMI are all about. The keynote speaker was Clyde Fessler, the former VP of business development for Harley-Davidson Motor Company. Everyone has heard of Harley-Davidson motorcycles so it was interesting to hear him talk about the ups and downs the company went through and what he learned from all of those experiences. His talk presented the four P’s of marketing; product, price, promotion, and place. Another P that he mentioned that is, if not, more important, was people. Mr. Fessler was an animated speaker and it was enjoyable to listen to him. His motivation and techniques were both inspiring and doable. I think that everyone benefited from listening to his
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speech. After the opening session, I headed off in search of some of the other presentations that were offered that day. The first session I attended was on fatigue. It so happened that my advisor, Professor Chawla, was the first speaker. He spoke about how cracks due to fatigue could actually show preferential cracking due to the large amount of porosity within PM steels. This topic was close to what I was studying for my poster project. After his talk I stayed in the fatigue session listening to the remaining speakers. At the Industry Recognition Luncheon, as a CPMT/Axel Madsen Conference Grant recipient, I was pointed toward a reserved seat near the front of the room. Soon after I arrived I had the privilege of meeting the chairman of the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology. After a while more people began to arrive and I soon met the other three grant winners. The lunch was great and I was able to socialize with many people in the PM industry and I got to see the results of the metallography contest. I love microscopic images, so seeing all of the artistic and natural images captured under a microscope was really interesting to me. It would be cool to enter the competition in the future because it is amazing how beautiful even the most basic things are when you get down to the atomic and microscopic level. After lunch the Exhibition Hall opened for conference attendees. Many different companies set up booths in the hall promoting their services relating to the PM industry. Not knowing a whole lot about the PM industry I knew even less about the companies involved, so as I walked through the exhibits it was interesting to see all of the different companies. Also in the exhibit hall, the design excellence awards were on display. I have not had much experience with PM so I was surprised at the many different applications covered. The items displayed ranged from all kinds of applications such as handcuffs, dental braces, hearing aids, and automotive parts. After my first day I was feeling a little better about being in a new place. It was easier to be at the conference after having met the other grant winners because they were more my age and shared more of my interests. On Tuesday, I attended the speaker meet-andgreet and enjoyed a bagel and coffee with the other grant winners. While there, the new president of APMI approached me and let me know Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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that my poster had been given one of the “outstanding poster” awards in the poster competition! I did not expect to get any sort of recognition so I was very excited. Later I attended the PM Design Excellence Awards Luncheon which highlighted the winners in the 2007 competition. And after lunch it was time to stand with my poster and answer questions from onlookers. Almost everyone who came by was impressed. It was really satisfying to have other people excited about something I was doing. Tuesday night was the main social event of the conference, “An Evening at Coors Field.” The accommodations we were given at the game were unbelievable. A baseball game will never be the same. We were served an amazing dinner in a luxury suite and the night got even better when I found out that the Colorado Rockies were playing the Arizona Diamondbacks. It almost felt like home! Unfortunately for the home team, the D’backs won! I met a lot of new people and I had a great time. It was one of the highlights of the conference for me. On the last day I attended more sessions and finally took down my poster and headed back to Phoenix. The experience I had in Denver was unforgettable. I was a CPMT/Axel Madsen Conference Grant recipient, I was able to attend this amazing conference in a great city, and to top it all off, I was one of two recipients of the “Outstanding Poster” award. I am so glad I was able to go to PowderMet2007 and I would definitely encourage anyone in the PM industry to attend the 2008 World Congress on Powder Metallurgy & Particulate Materials in Washington, D.C. DONALD SAMPSON Pennsylvania State University University Park, Pennsylvania I will be the first to admit that I was very skeptical at the thought of attending PowderMet2007. Having never been to a conference before, I was intimidated by a lack of experience. Day-to-day, I wasn’t sure what sort of functions I would be attending, and what would be expected of me. Also, having to present a poster covering my own research and the kinds of questions or criticisms I might endure was a frightening prospect. Finally, the simple fact that beyond my advisor and one other student I did not really know anyone attending the conference put me ill at ease. Upon arriving at PowderMet2007, all these fears were Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
quickly laid to rest. In the end, PowderMet2007 proved to be a most enjoyable and rewarding experience that was worthwhile professionally, academically, and socially. Arriving at the Hyatt Regency I was awed by the luxuriousness and elegance of our accommodations. This spectacular hotel provided excellent service and location adjacent to the Colorado Convention Center. In addition, the downtown location made for easy access to any number of Denver’s numerous attractions. It did not take long after the conference began for me to become comfortable with this new experience. The opening general session was nothing short of spectacular, inspiring the desire to strive for excellence in the field of powder metallurgy (PM). The keynote speaker, Clyde Fessler, formerly of the Harley Davidson Corporation, was charismatic, interesting, and funny during his presentation titled “The Rise and All of Harley-Davidson: The Building of a Brand.” From this point on, and to the conclusion of the conference, all my worries were allayed as I realized what a tight-knit community the PM industry really is. During the technical sessions, lunches, and conference events I met with former students from my own program, other students who participated in an international research experience with me, and professionals whose interests brought them in and out of my laboratory from time to time. In addition, I met numerous other people from a variety of backgrounds who, along with my fellow CPMT/Axel Madsen Conference Grant recipients, made the trip to Denver rewarding. This was particularly enjoyable as we took time to sample many of Denver’s best microbrews, steaks, and attended the conference’s main social event, “An Evening at Coor’s Field.” The professional and academic significance of attending the conference should not be undervalued. The technical sessions allowed me to broaden my horizons as to the cutting-edge technology on the forefront of the PM industry. Also, visiting the booths at the exhibit allowed me to talk with representatives from some of the finest companies in the PM industry. Finally, I would like to thank the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology for selecting me for this wonderful experience, and my advisor Dr. Ivica Smid for nominating me. After all the uncertainty, the only disappointing part of PowderMet2007
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was when I had to finally leave the wonderful city of Denver. MIKE SEXTON Drexel University Philadelphia, Pennsylvania I would first like to thank the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology for awarding me the funds to attend PowderMet2007 and my advisor, Professor Zavaliangos, for my nomination. Having been introduced to powder metallurgy (PM) last summer, it seemed like a niche process that only a few places performed. Consequently, it was surprising to see such a large number of attendees. Being a motorcycle owner and enthusiast, I found the keynote presentation by Clyde Fessler particularly interesting. I think he opened a lot of minds to creative ways of thinking for increasing the use and awareness of PM. Looking through the session schedule I noted that not only educational institutions but researchers from companies played a large part in the technical presentations. It was confusing to see companies sharing their efforts with their competitors, but as the day went on I realized that the PM industry is one that prefers to grow as a family rather than as cutthroat competitors. This realization was even more apparent as I attended the luncheons and other social events and began talking with other attendees. At the opening luncheon I spoke with two brothers, both with their own PM businesses. Listening to their perspective on the PM industry and how it has provided them with a rewarding career added newfound depth to my purpose at this event. Eager to learn as much as possible about ongoing research in powders, I was disappointed to realize that many presentations occurred concurrently. Fortunately, only on two occasions did I feel torn between any two. The breadth and diver-
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sity of topics presented offered something for everyone. Between modeling, sintering, atomization, and property enhancement, you would have had to tie me down to keep me in one room. Ever since I witnessed the atomization of a superalloy showering the cryogenic bath in the belly of a pilot gas atomizer, I cannot get enough of the new and interesting ways materials are being disintegrated into powders. Naturally, the sessions on centrifugal and close-coupled atomization methods provided grist for my curiosity mill. Not only were the technical sessions informative, but I learned a lot from discussing the products and services of the companies at their booths in the exhibit hall. I was intrigued by the use of coupled vibration and sonic energy resonance to increase the efficiency of sifting powders. I also enjoyed discussing the mechanics of spark plasma sintering and where research efforts are being directed in the companies that provide this service. I had an inkling that attendees would have little interest in my research on pharmaceutical powders and even though I was only asked one question, I relished the opportunity to speak with the other CPMT/Axel Madsen Conference Grant recipients and poster authors about their research and their involvement in PM. And now, as I am sure the other recipients have noted, I will reiterate the importance of an open forum amongst academe and industry to foster advancement and fuel progression. Well aware of the knowledge and experience gap between myself and the majority of the attendees, I never once felt anything less than a peer. I was even mistaken twice for a business owner while en route to Coors Field. I hope I get the chance to see everyone again in Washington, D.C. next year at the World Congress. Again, I extend my infinite gratitude to the Scholarships & Grants Committee of the Center for Powder Metallurgy Technology for granting me the opportunity to participate in PowderMet2007. ijpm
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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ENGINEERING & TECHNOLOGY
LUBRICANTS FOR HIGHDENSITY COMPACTION AT MODERATE TEMPERATURES Lhoucine Azzi,* Yannig Thomas** and Sylvain St-Laurent***
INTRODUCTION The quest for parts with high density fabricated by inexpensive shaping processes is a constant focus of the PM industry. Cost effective compaction processes available to the PM industry in the production of high-green-density components are die-wall lubrication, warm compaction, and cold compaction using specialty lubricants. Warm pressing,1 which involves pressing a preheated powder mix in a heated die (~100°C to 180°C), enables the fabrication of parts with high density and green strength by increasing the ductility of the ferrous powder particles. The gain in green density achieved by warm compaction compared with conventional cold compaction generally ranges between 0.12 and 0.30 g/cm3. The main drawbacks to this technology are the need for specialty presses and tooling to heat both the powder mix and the die. The need for internal lubricants to provide adequate lubrication at the die walls during both the compaction and ejection steps adds to the complexity of this process. Die-wall lubrication2 is also a promising route to promote high green density when high compacting pressures are used. The benefit of this technique is the possibility of significantly reducing the internal lubricant level in the powder mix, while maintaining good lubrication at the die walls during compaction and ejection of the parts. This technique is not widely used on a mass production scale because of concerns regarding its reliability. Recent improvements appear to have addressed most of these concerns.3 Cold compaction using conventional lubricants, such as metallic stearates or amide-based waxes, does not generally yield high-greendensity parts. Recently, more effective lubricants have been developed for conventional compaction at room temperature. Hammond 4 describes a lubricant system which is solid at ambient conditions, but which transforms to a liquid phase upon the application of pressure. It is claimed that this lubricant can be used at a reduced concentration due to the efficiency of lubrication arising from the transformation from solid to liquid. Because less lubricant is used, the green density
The nature of the lubricant and the conditions of compaction, in particular the temperature and pressure, affect the densification of powder metallurgy (PM) powder mixes. While the effect of pressure on densification is straightforward, the effect of temperature is more complex. Depending on the lubricant, an increase in the compaction temperature can significantly affect the level of friction at the die walls, as well as the lubricant distribution in the compact, and therefore affect the compressibility of powder mixes. In this study, the compressibility and lubrication behavior of PM powder mixes containing conventional and new lubricants for high-density applications are reviewed. The effect of temperature on the pressing response of powder mixes containing the new lubricants is assessed.
*Research Associate, Materials and Processes/Powder Forming, **Research Officer Industrial Materials Institute/National Research Council Canada, 75 de Mortagne, Boucherville, Québec, Canada J4B 6Y4; E-mail:
[email protected], ***Director, Product Development, Quebec Metal Powders Limited, 1655 Marie Victorin, Tracy, Québec, Canada, J3R 4R4
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is increased. Compaction processes in which a nonheated powder is compacted in a heated die have also been developed. 5 The temperatures involved are ~60°C; thus presses with specialty tooling are not required. In addition, the flowability of the powder mixes is less of a concern than in warm compaction in which the powder mix is heated. In this study, the compressibility and lubrication behavior of PM powder mixes containing conventional and new lubricants for high-density applications are reviewed. The effect of the compacting temperature on PM powder mixes containing the new lubricants is evaluated. BACKGROUND Several factors affect the green density of PM parts. Among these factors are friction at the die walls, the intrinsic compressibility of the powder, and springback after ejection.6 Friction at the die walls can be described by the sliding coefficient, η.7,8 For a cylindrical part of dia. D, compacted in a single-action press, the sliding coefficient at the completion of compaction can be calculated from the relation: η = (Pt/Pa)
AF [—— SH ]
(1)
where Pa is the pressure applied to the punch, Pt is the pressure transmitted to the stationary punch and H is the height of the cylinder. F is the cross-section area and S is the cross-section perimeter. Numerical values of η vary from 0 to 1: the higher the sliding coefficient, the lower the friction at the die walls, and the more uniform the density through the compact. The intrinsic compressibility of the powder is a measure of the densification of a powder mix, in the absence of friction at the die walls, i.e., the pressure transmitted to the powder compact is equal to the applied pressure. This pressure can be evaluated by the relation between the average IN die density (the density of the part under pressure) and the average pressure seen by the compact. It has been shown7,8 that, for a cylindrical compact of dia. D, the average pressure (net pressure) PNET can be evaluated utilizing the relationship: PNET = Pa*η
H (—— 2D ) = (P *P )1/2 a t
(2)
The green density of a PM compact is usually
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described in terms of the percentage of its porefree density (i.e., the density of a pore-free powder compact). In practice, the maximum green density attainable is ~98% of the pore-free density. The pore-free density is a function of the composition of the powder mix. Alloying additions such as copper and nickel increase the pore-free density of iron-base powder compacts while graphite and lubricant lower the pore-free density. The lubricant, with a density ~1 g/cm3, is the additive that has the largest effect on the pore-free density of a PM compact. For example, the effect of the concentration of an admixed lubricant (density 1 g/cm3) on an FC0205 powder mix containing 2 w/o copper and 0.6 w/o graphite is shown on Figure 1. A way to increase the pore-free density and green density is to reduce the lubricant concentration in the powder mix. However, this can prove to be difficult from a practical point of view. Indeed, lowering the lubricant content can dramatically increase friction at the die walls and impede compaction. Another strategy to increase the green density of a PM compact is to use alternative lubricants and processing conditions that favor expulsion of the lubricant from the green compacts during compaction. For a given lubricant concentration, this should increase the pore-free density and, as a result, the green density. It was shown9 that the compressibility of stearate/steel mixes could be improved by increasing the compacting temperature. However, this was not attributed to the higher amount of lubricant expelled from the green compact at a higher temperature, but rather to
Figure 1. Effect of lubricant content (density 1 g/cm3) on the pore-free density of a FC0208 powder mix
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LUBRICANTS FOR HIGH-DENSITY COMPACTION AT MODERATE TEMPERATURES
enhanced plastic deformation of the metallic particles during compaction. Moreover, the green density improvement was limited because of the significant increase in friction at the die walls as the compacting temperature was raised. For certain stearate/steel mixes, this gave rise to “stick and slip” during ejection. Friction at the die walls increased by as much as 15% when the compacting temperature was raised from room temperature to the softening points of the lubricants. This was attributed to the low viscosity of the lubricant under these compacting conditions. In a study on lithium stearate/steel mixes,10 it was confirmed that the higher green density measured at the higher temperature was not due to expulsion of the lubricant from the compact. A study of the lubricant distribution in the compacts showed that the lubricant had a tendency to flow towards the die-wall surface, but under the compacting conditions used, a limited amount of lubricant was expelled from the compact. It must be emphasized that in both studies, the compacting pressure was limited to 620 MPa (45 tsi) due to insufficient lubrication on the die walls that prevented the application of higher pressures. This could explain the small quantity of lubricant that was expelled from the green compacts. Lubricant systems that exhibit compatible rheological behavior at moderate compacting temperatures (50°C to 100°C) result in lubricant expulsion from green compacts, while maintaining good lubrication at the die walls at pressures >760 MPa (55 tsi), have been developed. As a result, PM parts with improved green density can be obtained. EXPERIMENTAL PROCEDURE The compaction and ejection characteristics of FC0205 and FC0208 powder mixes made with ATOMET 1001 atomized steel powder were characterized at different compaction temperatures. These two mixes contain 2 w/o Cu (ACuPowder 165) and 0.6 w/o and 0.8 w/o natural graphite (Southwestern 1651), respectively. These powder mixes were admixed with conventional ethylene bis-stearamide (EBS) lubricant, and with two proprietary lubricants coded Lube A and Lube B, which were developed for high-density applications. Lube A and Lube B have a similar chemical structure but with softening points of 60°C and 80°C, respectively. The compaction and ejection characteristics of the FC0208 powder mix were Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
evaluated on an instrumented laboratory singleaction press (Powder Testing Center (PTC)11). Cylindrical specimens with a height of 15 mm and an aspect ratio of 6.3 (4.5 times the aspect ratio of rectangular bars (TR bar: 31.75 mm × 12.7 mm × 6.35 mm), were pressed in a WC-Co die having a 9.525 mm dia., at a compacting speed of 1 mm/s. The PTC press permits continuous recording of the moving punch displacement, the forces applied to the moving punch and transmitted to the stationary punch, and the IN die density, during the entire compaction and ejection processes. This allows for the determination of the intrinsic compressibility, the sliding coefficient, and the ejection forces. The stripping pressure (which corresponds to the force needed to start the ejection process divided by the friction area) and the ejection unit energy were estimated from the ejection curve in order to compare the lubricating performance. The ejection unit energy is evaluated from the area under the ejection curve (force vs. displacement) divided by the displacement and the friction area. The lubricant losses during compaction and after ejection were also measured on the FC0208 powder mix. TR bars were compacted at 760 MPa at 65°C to green densities of 6.8 g/cm 3 , 7.0 g/cm3, and 7.3 g/cm3, using a floating die and a 100 st hydraulic press. The specimens were lightly polished to eliminate the lubricant on the sample surface and then sintered at 1,120°C for 30 min in dissociated ammonia to remove lubricant. Compact weights before and after sintering were measured. The behavior of the FC0205 powder mix was evaluated on an industrial 150 st Gasbarre mechanical press. Straight gears (15 teeth), 25.4 mm thick, with an aspect ratio of 4.7, were pressed in a CPM15V tool steel die preheated to a temperature of 70°C. The steady-state temperature of the parts was ~80°C. The compacting pressure was varied from 415 to 830 MPa (30 to 60 tsi). Compressibility curves were monitored and ejection forces were recorded. RESULTS AND DISCUSSION Effect of Temperature on Compressibility and Ejection Forces Figure 2 shows the effect of temperature on the green density of two FC0208 powder mixes, compacted on the PTC press, containing 0.75 w/o EBS and Lube A, respectively. At room tempera-
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Figure 2. Effect of temperature on the green density of FC0208 powder mixes, compacted at 760 MPa, containing 0.75 w/o EBS or Lube A
Figure 4. Intrinsic compressibility of FC0208 powder mixes, containing 0.75 w/o EBS or Lube A at 55°C
ture, the green density of the two powder mixes is similar. However, for compacting temperatures near and above the softening point of Lube A (60°C), the green density of the mix containing Lube A experiences a significant jump, while that of the other mix remains essentially constant. At a compacting pressure of 760 MPa (55 tsi) and a temperature of 65°C, the green density of the mix containing Lube A is approximately 0.2 g/cm3 higher than that of the mix containing the EBS lubricant, and about 99.1% of the pore-free density. As shown in Figures 3 to 5, this increase in green density can be related, in part, to the increase of the intrinsic compressibility and the decrease of the springback after ejection when the compacting temperature is near or above the soft-
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Figure 3. Intrinsic compressibility of FC0208 powder mixes, containing 0.75 w/o EBS or Lube A at room temperature
Figure 5. Effect of temperature on the axial springback of FC0208 powder mixes containing 0.75 w/o EBS or Lube A
ening point of Lube A. This significant increase in the intrinsic compressibility can be explained by the improvement in internal lubrication, and by the expulsion of a portion of the lubricant from the green compacts. In the compacting temperature range used in this study, the effect of temperature on the ductility of the metallic powders should have limited effect. Another factor explaining this green density increase is the behavior of the sliding coefficient as a function of the compacting temperature (Figures 6 and 7). The sliding coefficient of the mix containing Lube A is maintained, or even improved, at a compacting temperature near or above the softening point of Lube A. This is a major difference compared with the warm compaction of stearate/steel mixes near the Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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LUBRICANTS FOR HIGH-DENSITY COMPACTION AT MODERATE TEMPERATURES
Figure 6. Effect of applied pressure on the sliding coefficient of FC0208 powder mixes, containing 0.75 w/o EBS or Lube A, compacted at room temperature
Figure 7. Effect of applied pressure on the sliding coefficient of FC0208 powder mixes containing 0.75 w/o EBS or Lube A, compacted at 55°C
Figure 8. Effect of temperature on the stripping pressures of FC0208 powder mixes containing 0.75 w/o EBS or Lube A
Figure 9. Effect of temperature on the stripping pressures of FC0208 powder mixes containing 0.75 w/o EBS or Lube A
melting points of the stearate lubricants, in which a sharp decline in the sliding coefficient is observed. 9 The increase in green density with temperature observed in this study can be explained by the improvement of the intrinsic compactability, the decrease of the springback after ejection, and by the ability of the lubricant (Lube A) to maintain good lubrication at the die walls during compaction. Figures 8 and 9 show the variation of the stripping pressure and ejection energy, for the two powder mixes containing EBS and Lube A lubricants, with the compacting temperature. Again, in sharp contrast to warm compaction of stearate/ steel mixes,9 the ejection performances of the mix containing Lube A are maintained, even though Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
the compacting temperature is near to the softening point of Lube A. This property allows highdensity, high-aspect-ratio PM compacts fabricated without damaging the tooling dies. Effect of Temperature on Lubricant Loss During Compaction Figure 10 shows that no lubricant was expelled from the powder compacts pressed from the mix containing the EBS lubricant. Similar behavior was recorded for the mix containing Lube A for green densities <6.8 g/cm3. However, for higher densities, the lubricant loss increased rapidly with green density. For a compacting pressure of 760 MPa (green density 7.3 g/cm3), more than 25% of the initial quantity of lubricant was
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LUBRICANTS FOR HIGH-DENSITY COMPACTION AT MODERATE TEMPERATURES
Figure 10. Total lubricant loss during compaction at 65°C and after ejection of FC0208 powder mixes containing 0.75 w/o EBS or Lube A
expelled from the green compact. This represents an increase in the pore-free density ~0.1 g/cm3, or 1.2%. A green density of 7.3 g/cm3 represents 99.1% of the initial pore-free density, or 98% after the lubricant loss is taken into account. Expulsion of the lubricant from the compact decreases the amount of lubricant present in the pores. This delays the inhibition of compaction at higher densities; thus, higher green densities can be achieved. The variation of the pore-free density as a function of the compacting temperature may also have an impact. The mechanisms by which the lubricant is expelled from the green compact are complex. If we consider the case in which the lubricant is in a liquid or a semi-liquid state, we can assume that the lubricant flows into the porous compact by pressure-assisted capillary flow. A simple model describing the kinetics of penetration of a liquid into a porous medium was developed by Washburn.12 The model gives the relation: σDcos(θ) L2 = ———— t 4µ
(
)
(3)
where L is the depth of penetration of the liquid, t is the time, σ is the surface tension of the liquid, θ is the contact angle between the solid and the liquid, D is the average pore diameter, and µ is the dynamic viscosity of the liquid. As compaction proceeds, both pore volume and pore size decrease, and from Equation (3) it becomes more and more difficult to move the lubricant through the pores towards the die walls. As the pressure is increased, the lubricant fills
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the pores. Once the pores are filled, the lubricant will eventually exit the compact, if it reaches the die walls before the pores are closed. From Equation (3), this will depend primarily on the viscosity of the liquid. The viscosity must be sufficiently low to allow for the rapid movement of the liquid and, at the same time, sufficiently high to provide adequate lubrication at the die walls. Lubricant expulsion towards the die walls will continue as long as the applied pressure is higher than the capillary pressure required to move the liquid lubricant. It was observed experimentally that expulsion of the lubricant could continue, even after ejection of the green parts from the die. After ejection, the pressure is relaxed in the solid phase, but not in the liquid phase. This induces a backward pressure, promoting expulsion of the lubricant. The total lubricant loss includes the expulsion of the lubricant during compaction and after ejection. Expulsion of the lubricant after ejection can be controlled easily by controlling the viscosity and the concentration of the lubricant. In this study, green density is improved, even at low compacting pressures where the pores can readily accommodate the lubricant. At a low compacting pressure, the green density improvement is related to the fact that the good lubrication properties of Lube A enable a reduction in friction, and therefore an increase in density. At higher compaction pressures, the excellent lubrication properties and the properties of the lubricant itself (viscosity) allow the application of sufficient pressure to expel the lubricant from the compact. Therefore, the increase in intrinsic compressibility, while maintaining low friction at die walls, explains the increase in density at high compaction pressure. Validation on an Industrial Press Expulsion of lubricant towards the die walls is a kinetics-driven phenomenon and, as such, it depends on the compaction rate. The compaction rates of laboratory presses are significantly lower than those that exist under industrial conditions. In order to validate the results observed on the laboratory presses, gears (15 teeth) were pressed on an industrial press at a stroke rate of 10 parts/min. FC0205 powder mixes containing 0.6 w/o EBS or Lube B were compacted. The porefree density of these mixes is 7.47 g/cm3. Lube B is a lubricant designed for high-density applications requiring excellent lubrication properties. Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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Figure 11. Compressibility of FC0205 powder mixes containing 0.6 w/o EBS or Lube B. Results for the EBS lubricant correspond to 12.7 mm (0.5 in.)-thick gears compacted at 60°C, while results for Lube B refer to 25.4 mm (1 in.)-thick gears compacted at 80°C
The compaction temperature was near to that of the softening point of Lube B (80°C) for the mix containing Lube B. It had to be set at a lower temperature for the mix containing the EBS lubricant (60°C) because of lubrication difficulties. Even at this compacting temperature, lubrication with this mix was insufficient to press gears with heights >12.7 mm. Figure 11 shows the compressibility of the two powder mixes. At 830 MPa (60 tsi), the green densities of the mixes containing Lube B and EBS were 7.3 g/cm3 and 7.23 g/cm3, respectively, or 97.7% and 96.6%, respectively, of the pore-free density. It must be emphasized that the surface of friction of the gear compacted with Lube B (6,452 mm2) was twice as high as that for a gear made using the EBS lubricant. As shown in Figure 12, the ejection performances of the mix containing Lube B were still better than those of the mix containing the EBS lubricant. CONCLUSIONS Lubricant systems designed for pressing at moderate temperature (<100°C) were developed. The compressibility and lubrication behavior of powder mixes containing conventional and these newly developed lubricants were evaluated as a function of the compacting temperature. It was shown that significantly higher green densities could be obtained with these lubricants. This was attributed to their ability to migrate and exit green compacts at compacting temperatures near their Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Figure 12. Ejection behavior of FC0205 powder mixes containing 0.6 w/o EBS or Lube B. Results for the EBS lubricants correspond to 12.7 mm (0.5 in.)-thick gears, while results for the other lubricants refer to 25.4 mm (1 in.)-thick gears
softening point. Capillary flow, assisted by pressure, was proposed as the mechanism for explaining lubricant expulsion during compaction. The amount of lubricant expelled from the green compacts depends on the viscosity and chemical nature of the lubricant. The viscosity must be sufficiently low and the pressure sufficiently high to allow the lubricant to reach the die walls before pore closure. Concurrently, the viscosity of the lubricant must be sufficiently high to provide adequate lubrication at the die walls. When these conditions are fulfilled, high-density PM parts with high aspect ratios can be compacted with these lubricants. The density gains are similar to those achieved in warm compaction. However, the compacting temperatures are significantly lower. This approach is a viable alternative to warm compaction. REFERENCES: 1. H.G. Rutz and F.G. Hanejko , “High Density Processing of High Performance Ferrous Materials”, Advances in Powder Metallurgy & Particulate Materials, compiled by C. Lall and A.J. Neupaver, Metal Powder Industries Federation, Princeton, NJ, 1994, vol. 5, pp. 117–134. 2. P.E. Mongeon, S. Pelletier and A. Ziani, “Die Wall Lubrication Method and Apparatus”, U.S. Patent # 6,299,690, October 9, 2001. 3. IMFINE technical data sheet, www.imfine.ca;
[email protected]. 4. D. Hammond, “Lubricant System for Use in Powdered Metals”, U.S. Patent # 6,679, 935, January 20, 2004. 5. D. Milligan, P. Hofecker, U. Engström, M. Larsson and S. Berg , “A Comparison of Methods of Reaching High Green Densities Using Elevated Temperatures”, Advances in Powder Metallurgy & Particulate Materials, compiled by W.B. James and R.A. Chernenkoff, Metal Powder Industries
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Federation, Princeton, NJ, 2004, part 10, pp. 28–34. 6. S. St-Laurent, F. Chagnon and Y. Thomas, “Study of Compaction and Ejection Properties of Powder Mixes Processed by Warm Compaction”, Advances in Powder Metallurgy & Particulate Materials, compiled by H. Ferguson and D.T. Whychell, Metal Powder Industries Federation, Princeton, NJ, 2000, part 3, pp. 79–91. 7. Z. Korcsack, S.Gasiorek and K.K. Kaminski, “Compacting Lubrication for Metal Powders”, Adv. Powder Technol., Brill Academic Publishers, Leiden, Holland, 1990, Vol.1, pp. 279–286. 8. S. Gasiorek, Z. Korcsack and K.K. Kaminski, “Compressibility of Metal Powders”, Advances in Powder Metallurgy, compiled by T.G. Gasbarre and W.F. Jandeska, Jr., Metal Powder Industries Federation,
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Princeton, NJ, 1989, Vol. 1, pp. 53–62. 9. Y. Thomas, S. Pelletier and J.M. McCall, “Effect of Compaction Temperature on the Lubrication Behavior of Dif ferent Lubricant/Steel Powder Compositions”, Advances in Powder Metallurgy & Particulate Materials, compiled by J.J. Oakes and J.H. Reinshagen, Metal Powder Industries Federation, Princeton, NJ, 1998, part 11, pp. 25–38. 10. M. Gagné, Y. Thomas and L.P. Lefebvre, “Effect of Compaction Temperature on the Lubrication Distribution in Powder Metal Parts”, ibid reference no. 9, pp. 39–53. 11. Powder Testing Center, model PTC-03DT, manufactured by KZK Powder Technologies Corp., Cleveland, Ohio. 12. E.W. Washburn, “The Dynamic of Capillary Flow”, Phys. Rev., 1921, vol. 17, pp. 273–283. ijpm
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RESEARCH & DEVELOPMENT
R&D IN SUPPORT OF POWDER INJECTION MOLDING: STATUS AND PROJECTIONS Randall M. German*
INTRODUCTION There is a natural history to how a technology develops and reaches maturation, and it is often mapped into the product life cycle.1 In this regard, powder injection molding is similar to many other fields, passing through a series of stages. At first there is a period of empirical discovery resulting in “secret recipes” followed by a plateau during market development. The most exciting stage is the period of rapid growth when both profits and R&D investments peak. However, there is an inflection point where growth tapers off as sales approach maturation. Finally, without new vitality, a long period of decline occurs with symptoms of increased competition, excess capacity, and falling profits. This behavior is evident in most technical areas and has been documented for a wide range of products and even basic materials. (Note this does not relate to “brands” such as one feedstock versus another, but with the overall field of PIM which is reflective of the “product”.) Technologies that are initially underfunded share the characteristics of being empirical and dependent on licensing for growth. This was the case for PIM in its early days. But as scientific principles were discovered and applied, PIM moved into a sustained growth phase. PIM, like so many technologies, follows a natural curve that can be traced via quantitative measures. Since the typical growth curve is understood, it is relevant to document the current status, realizing that trends in PIM R&D are critical to commercial developments. A statistical profile has been created for PIM R&D. The profile was used to understand the current status and future research trajectory. The findings show that innovations are still emerging, but R&D in general, 2 and specifically PIM R&D, is moving to low-cost regions. Competition in PIM production is having a significant impact on where PIM R&D is performed, which indirectly has an influence on future profits and other financial measures.3
Since for most technologies there is a close coupling between research and market success, it is possible to monitor a few key technological parameters to predict market trends. Powder injection molding (PIM) is following a fairly classic development cycle where research and development (R&D) leads sales and profits. Detailed figures on R&D expenditures in support of PIM are elusive, so this paper relies on other measures, such as publications, patents, presentations, equipment investment, and staffing, to track PIM R&D. From this analysis emerges a sense of the future directions for PIM such as geographic and market shifts. PIM R&D is growing rapidly in Asia with a focus on developing standard materials, design, and applications. Meanwhile, in North America and Europe the transformation in PIM R&D is toward more computer simulations, titanium and tungsten, and smaller devices. At the same time industry needs for process optimization R&D and cost reduction R&D are being internalized.
CAPTURING PIM R&D DATA Besides published literature, several key trends were identified based on presentations given at various conferences that cover PIM. *CAVS Chair Professor of Mechanical Engineering, Director, Center for Advanced Vehicular Systems, Mississippi State University, 200 Research Boulevard, Starkville, Mississippi 39759, USA, E-mail:
[email protected]
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R&D IN SUPPORT OF POWDER INJECTION MOLDING: STATUS AND PROJECTIONS
For this study, key information sources were from 30 citations.4–33 These data were supplemented by a large number of survey responses. Thus, the inputs largely clustered around the following five areas: 1. Financial performance—several prior market and performance studies 2. Patent activity— accessed directly form the U.S. Patent and Trademark Office 3. Publications activity—Web searches, literature databases, publication archives 4. Expert opinions—survey of 175 R&D leaders identified by publications and presentations; these individuals also provided updated publication data 5. Nonarchival data—analysis of reports, unpublished manuscripts, case studies, telephone contacts, pending patent applications, and other data These resources were used to understand PIM and the maturation of its R&D base. Through these resources, trends were extracted and timebased changes were accumulated to identify future directions. Today, efforts to monitor knowledge accumulation are assisted significantly by computer search tools. Several of these were employed here, including citation indexes, journal Web sites, patent listings, traditional search engines, and proprietary databases. Key emphasis was put on journal articles and patents. Special care was taken to capture these activities without duplication. To identify the most important publications, an impact factor (the h-factor) was employed. The h-factor relies on ranking the number of citations by other publications.34 A high h-factor reflects important contributions; the highest h-factors in physics and the life sciences are >100. To avoid ambiguity, in the following discussion, both “molding” and “moulding” were used to form composite searches, with corrections for those publications that used both terms. Searches of patent databases and publications revealed that the search terms must be properly selected to identify relevant articles. For example, “powder” + “molding” generated 46,414 patent citations, far in excess of the expected number. As listed in Table I, the most significant search term was “powder injection molding.” More than 40 search word combinations were tested and many proved to be fruitless. The highest frequency of valid citations in patent and publication searches
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TABLE I. PHRASES AND KEYWORDS ASSOCIATED WITH PIM R&D, RANKED BY IMPACT FACTOR (INCLUDES MOLDING AND MOULDING) Phrase “Powder injection molding” “Ceramic injection molding” “Metal injection molding” “Debinding” “Metal powder injection molding” “Debind” “Carbide injection molding” “Debound”
h-Factor 33 25 16 11 8 5 2 2
resulted from word combinations such as “binder” + “powder injection molding” and variants on the first word such as “metal,” “ceramic,” or “carbide.” Searches based on the term “metal injection molding” produced 1,810 publications, but about 30% were on thixomolding, metal tooling for injection molding, rapid prototyping, bonded magnets, and other topics. Searches using “MIM” gave 89,900 publications, many of which were associated with tumors, linguistics, immunodeficiency, and other distant concepts. Thus, use of “powder injection molding” or “metal powder injection molding” was the most fruitful. Table I lists the most significant search terms based on impact factors. At the end of 2006, the estimated PIM publication count was 3,120 and the estimated U.S. Patent count was about 400. However, probably only 83 patents were specific to PIM technology in the past 20 years. Unpublished conference papers were included in the tabulation, including 744 presentations where handouts were distributed in lieu of proceedings. Besides presentations, patents, and publications, 175 senior researchers were identified via various databases and publications. They were contacted and asked to respond to a brief survey on past, current, and future activities. About 10% of the respondents said they had discontinued R&D efforts in PIM. About 20% had moved, retired, were no longer living, found new employment, or were otherwise no longer involved in PIM. Over 30% provided full data and a few provided only partial data; thus, the survey achieved more than a 60% response, with half of the responses in the form of full participation. SCALE OF PIM R&D Early in a new technology statistics from the product life-cycle analysis show upwards of 10% Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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Figure 1. Product life cycle in terms of sales with overlaid plot of appropriate R&D investment. Typically, when a technology is young, sales are small but up to 10% of sales are invested in R&D, usually for product development. As sales finally grow, the total R&D commitment peaks at the sales inflection point, usually averaging about 5% of sales. When the peak in sales is approached, the focus is on R&D for process improvements and cost reductions. Here the R&D investment drops to 1% of sales. When sales go into a prolonged decline, then R&D investment falls below 0.5% of sales
of sales devoted to R&D. As sales grow, a typical R&D investment strategy is shown in Figure 1. The absolute peak in R&D investment is at the inflection point in sales. Since products are at many different stages on the product life-cycle curve, in the U.S. the overall industrial R&D investment averages 2.7% of sales, but it is smaller at 2.3% globally.3 There are several ways to capture the total R&D investment in PIM. From various studies,4–33 the cumulative global sales for PIM since inception passed $8.7 billion in 2006. Profits are more difficult to assess, but the same sources suggest that up to 1991, the total loss for PIM was about $45 million, while the profit during the 1990s was upwards of $500 million (before interest and taxes). With reduced business and increased competition in recent years, cumulative profit from 2000 to 2006 is calculated at $100 million. For these estimates, an inflation of 5% was assumed. These and other data provide the following parameters for PIM R&D investment to date: Sales: Based on cumulative industry sales since inception to 2006 of $8.7 billion and an average investment of 2.5% of sales in R&D, with leveraging (10% industry R&D on average allocated to academe or government laboratories, which then leverage this by a factor of five), the total is Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
$326 million, with a probable error of $35 million. Profits: Based on cumulative estimated profits from PIM of $555 million, a typical allocation of 40% of profits to R&D, and with the government, academic, and foundation leveraging levels cited for sales, the total R&D investment is $330 million, with an error of $50 million. Publications: Based on 3,120 published papers (~45% in journals, 45% in conference proceedings, and 10% in magazines), a journal article on average results from $150,000 in R&D expenses, a conference publication results from $50,000, and a magazine article results from $20,000. This gives a total value of $287 million, with an estimated error of $45 million. Patents: Global patent activity is focused on the U.S. which accounts for nearly 200,000 new patents per year at an average R&D cost of $5 million per patent in industry and $43 million per patent in academe. Although 400 patents were identified, 25% were issued prior to the emergence of a PIM industry (early ceramic molding ideas), and about half of the remaining patents relate to bonded magnets, filled polymers, and related peripheral fields. This leaves 83 patents (mostly industrial) that are clearly the result of PIM R&D, for an investment of $415 million, but with a large error of $200 million. Researchers: Based on an average of 255 researchers over the past 20 years (the peak was 325 in 1996), with about 65% employed at universities, with a current expenditure per investigator of $200,000 per year in industry in the U.S. and $125,000 per year in academe, and with discounts for lower-cost portions of the world (further realizing that many investigators are not full time on PIM; for example, graduate students are only half time), gives a $428 million cumulative investment with an error of $200 million. The large error arises because costs at sites such as China, Korea, and India are not well documented. Capital Expense: It is recognized that industry invests on average 10.3% of sales in combined capital expense and R&D. Since previous reports on cumulative capital expense are published, the residual can be assigned to PIM R&D activities, giving $276 million, with an error ~$100 million. These five approaches are combined in Table II, giving an estimate of the cumulative PIM R&D investment at about $344 million, a standard deviation of $64 million, but with a realistic error of $105 million.
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TABLE II. ESTIMATES OF GLOBAL R&D INVESTMENT IN PIM Basis Cumulative industry sales Cumulative industry profits Cumulative publications Patent activity Research personnel Capital expense
PIM R&D ($ million)
Error ($ million)
326 330 287 415 428 276
35 50 45 200 200 100
TABLE III. SOME SUMMARY STATISTICS ON PIM AND PIM R&D Measure
$ Million
Cumulative global PIM industry sales Cumulative global PIM industry profits Cumulative global PIM industry capital investment Cumulative global PIM R&D expenditures (all sources) Cumulative global PIM industry R&D expenditure Cumulative global PIM expenditures (academe, government laboratories & independent research centers)
8,700 555 620 344 230 114
As summarized in Table III, of the cumulative R&D investment in PIM, industry has provided about $230 million, the balance being derived from government, academe, and foundation sources. A good example of leveraging was the development of an aqueous binder system for PIM that was 50% subsidized over 15 years by several government programs. METRICS OF R&D GROWTH Knowledge is a critical factor in relation to commercial progress in a technical field. To assess the situation in PIM, the global publication database was assessed. Over 2,800 of the 3,120 publications were collected and categorized. The resulting partition, based on subject, materials, sources, topics, and other attributes, provides a clear indication of the situation in PIM. Geography The geographic trends in PIM R&D help predict locations for future activity concentration. In this study, the distribution was based on where the research was performed. If an investigator performed the study while in another country, then the host country is credited. In terms of publications, the U.S. is the largest with nearly 46% of the publications, followed by Japan with 14%. Third ranking goes to Germany with 9%, followed by the U.K., China, Taiwan, and Korea. Additional research publications were identified from
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Figure 2. Geographic distribution (%) of publications on PIM R&D
Australia, Austria, Belgium, Brazil, Canada, Columbia, the Czech Republic, Denmark, Egypt, Finland, France, India, Iran, Ireland, Israel, Italy, Latvia, Malaysia, Norway, Portugal, Romania, Russia, Singapore, Slovenia, South Africa, Spain, Sweden, Switzerland, Thailand, Turkey, and the Ukraine. In total, these countries account for only 16% of the total. Figure 2 illustrates the geographic information in the form of a pie chart grouped as Asia, Europe, and North America. The remaining large geographic regions of Africa, Australia, the Middle East, and South America constitute <6% of the PIM R&D publications. A time-based trend analysis helps to understand the geographic shift in recent times. For the past 20 years the publication rate in the U.S. has been fairly constant, while publications from the U.K. have been in decline since 2000. On the other hand, publications from Germany and Japan ramped up in the late 1990s, while more recently Korea and Taiwan exhibited significant increases in activity. In the past five years there has been a dramatic increase in publications from China. Since publications are coupled to government and industry investments in R&D, these trends predict a major shift in PIM activity to China, Korea, and Taiwan. Other new actors include Brazil, France, Singapore, and Turkey. Topic The theme for each publication was assessed via searches on keywords. Six broad categories were used in the sorting process, as shown in Figure 3; Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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Small (nanoscale) powders targeted at microminiature components Indeed, one direction seems to be toward the fabrication of microminiature devices using nanoscale powders. Other opportunities cited were in biomaterials. Interestingly, 60% of the PIM R&D groups have some form of international collaboration. A few R&D topics were frequently noted as being in decline, examples being binder development, large components, and improved process control. Figure 3. Topical focus distribution in the PIM literature, with an apparent shortfall on process and design data
Materials (tending to show that a certain material is possible) Process (typically focused on the effect of independent parameters on the product) Science (efforts to explain behavior and characterize products or processes) Credibility (primarily associated with documentation of final properties) Design (information on component size, shape, complexity, tolerances, or performance) Market (primarily data on sales, profits, costs, applications, or successes) These categories reflect maturation toward commercialization. The largest body of work has been focused on determining the attendant scientific principles: for example, the kinetics of binder burnout. Such articles account for 23% of the publications. On the other hand, process descriptions constitute the smallest topical coverage, accounting for only 11% of the papers. Design information at 12% also appears guarded, while contributions focused on materials, markets, and overall credibility are prevalent at 17% to 20%. The data show a reluctance to share process information; however, the low level of design information is not favorable. Novel designs, processes, and features are emerging, but the technology is not being aggressively promoted. More attention is needed on design data such as tolerances, sizes, and shapes, similar to that presented in recent publications.35,36 The PIM R&D community is moving in several directions, of which a few stand out as receiving the greatest attention: Modeling and simulation Processing refinements (cost reductions, improved tolerances, reduced pollution) Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Publications A survey of the R&D community showed a recent average publication rate of 0.9 papers per senior investigator per year. With a current population of 148 identified active senior researchers, this suggests 133 publications per year, which is close to the 128 papers identified in 2006. Note that the peak publication years were in the 1995 to 2000 span, over which one-third of the total literature was generated. Figure 4 plots the recorded publication rate (percent of total in two-year increments to level the effects of large meetings such as the Powder Metallurgy World Congress) to illustrate how PIM has fallen out of favor with the R&D community in recent times. Publications in PIM occur in a broad array of forums, with about 45% in conference proceedings. Based on the forum for the publication, it is possible to identify the intended audience. The results show that over 50% of the publications are
Figure 4. PIM publication rate in two-year increments, showing a decline since ~1996
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TABLE IV. RANK LISTING OF INFORMATION SOURCES FOR PIM R&D BASED ON H-FACTOR CITATIONS (ACCOUNTING FOR 50% OF ALL PUBLICATIONS) 1. International Conference Proceedings (such as World Congress of Powder Metallurgy) 2. Journal of the Japan Society of Powder and Powder Metallurgy 3. Metal Powder Report 4. Powder Metallurgy 5. International Journal of Powder Metallurgy 6. Journal of the American Ceramic Society 7. Journal of Materials Science 8. Microsystems Technology 9. Journal of the European Ceramic Society directed at the powder metallurgy (PM) community; 20% are in traditional materials science publications (including ceramics); and 30% are in general engineering forums. Over 50% of the published information on PIM is found in the few sources identified in Table IV. This is a rank listing based on h-factor citations. A plateau in the publication rate in North America is evident. More recently, a rapid growth has taken place from Asian scientists as is evident from the position of the Japanese PM journal. In the survey of the PIM R&D community, the preferred publication forums were generally these same journals. Conferences There are three main forums for presentations emanating from PIM R&D. The main forum tends to be topical PIM meetings, including variants on the PIM Symposium and the subsequent PIM Conference that ran from 1990 to 2006 (Albany, San Francisco, Boulder, State College, Orlando, and San Diego). Similar meetings have been held with less frequency in Europe, Korea, Japan, and Taiwan. These tend to embrace an average of 35 papers at each meeting. The second major conference for the PIM R&D community has been the biannual PM World Congress (San Francisco, Paris, Washington, Granada, Kyoto, Orlando, Vienna, and Busan). This meeting averages 30 presentations on PIM. Finally, the regional PM or ceramics meetings (Europe, Japan, U.S.) tend to be highly variable in PIM content. It appears that many of the papers at the regional PM meetings are repeats of the presentations from the other meetings. This survey of the PIM R&D industry showed that the PIM Conferences and regional materials
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meetings were the most common forums for presentations, followed by the biannual PM World Congresses. STATUS Groups and Centers From the survey responses, PIM R&D is clearly distributed on a global basis, and the larger efforts are migrating to lower-cost regions. Table V lists some of the current PIM R&D effort, including contacts. Reports were provided from 20 different TABLE V. SOME ACTORS IN PIM R&D Universities and University-Based Centers Ajou University, Suwon, Korea, Professor Byung-Ohk Rhee,
[email protected]. Expertise on process control, computer simulation, and new PIM technologies. Central South University, Key State Laboratory for Powder Metallurgy, Changsha, China, Professor Jinglian Fan,
[email protected]. Large PIM R&D group with outstanding output of publications, patents, and students with current focus on cemented carbides and tungsten alloys. Chalmers University of Technology, Gothenburg, Sweden, Professor Lars Nyborg,
[email protected]. Rheology and feedstock development for new materials. Far East University, Tainan, Taiwan, Professor Jenn Shing Wang, jswang@ cc.feu.edu.tw. Focus on debinding and sintering processes for ferrous systems. Istanbul Technical University, Istanbul, Turkey, Professor Burak Ozkal,
[email protected]. Investigating tungsten and aluminum processing. Karadeniz Technical University, Trabzon, Turkey, Professor Fazli Arslan,
[email protected]. PIM manufacturing techniques, use of larger powders, and common materials. Kyushu University, Fukuoka, Japan, Professor Hideshi Miura, miura@mech. kyushu-u.ac.jp. Leading PIM program in Japan focused on high-performance materials, titanium and maraging steels, and microminiature components. Marmara University, Istanbul, Turkey, Dr. H. Ozkan Gulsoy, ogulsoy@ marmara.edu.tr. Program covers both metallic and ceramic materials. Mississippi State University, Center for Advanced Vehicular Systems, Starkville, MS, U.S., Professor Seong Jin Park,
[email protected]. Developing software to integrate molding, debinding, and sintering simulations as applied to microminiature components in titanium. Musashi Institute of Technology, Tokyo, Japan, Professor Ken-ichi Takagi, ktakagi @sc.musashi-tech.ac.jp. Newer program looking at hard boride cermets for automotive components. Nanyang Technological University, Singapore, Professor Ngiap Hiang Loh (processing)
[email protected] and Professor Yee Cheong Lam,
[email protected]. Teams focused on precision, process optimization, microminiature molding, and numerical modeling. National Taiwan University, Taipei, Taiwan, Professor Keun Shyang Hwang (metallic)
[email protected] and Professor Wen-Cheng J. Wei (ceramic)
[email protected]. Complementary groups providing academic support in both metals and ceramics; work includes some very high-strength materials supported by computer simulations. National Taiwan University of Science and Technology, Taipei, Taiwan, Professor Shun-Tian Lin,
[email protected]. Academic program focused on industry support.
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TABLE V. SOME ACTORS IN PIM R&D continued Universities and University-Based Centers Oregon State University, Oregon Nanoscience and Microtechnologies Institute, Corvallis, OR, U.S., Professor Sundar V. Atre,
[email protected]. Focus on models and techniques for the fabrication of microminiature components from nanoscale ceramic powders. Pennsylvania State University, Center for Innovative Sintered Products, State College, PA, U.S., Dr. Donald Heaney,
[email protected]. Hybrid company– university effort involved in military-funded R&D. Pohang University of Science and Technology, Pohang, Korea, Professor Tai Hun Kwon,
[email protected]. Focus on simulations, cemented carbides, and microminiature components. San Diego State University, San Diego, CA, U.S., Professor Eugene Olevsky,
[email protected]. Process simulation with focus on constitutive model of sintering densification and component warpage. Sakarya University, Adapazari, Turkey, Professor Fehim Findik, findik@ sakarya.edu.tr. General metallic program that supports light metals research. Sharif University of Technology, Tehran, Iran, Professor Abdolreza Simchi,
[email protected]. Efforts in stainless steel and zirconia, including two-material molding and sintering. TOBB Economics and Technology University, Ankara, Turkey, Professor Süleyman Saritas¸ ,
[email protected]. Examining developments in molding and rheology with emphasis on stainless steel. Tomas Bata University in Zlin, Polymer Center, Zlin, Czech Republic, Dr. Berenika Hausnerova,
[email protected]. Rheological properties and medical applications, especially using composites. Tsinghua University, Beijing, China, Professor Yunzin Wu, yxwu@mail. tsinghua.edu.cn. Working on titanium, intermetallics, stainless steel, and process simulations. Universidad Carlos III de Madrid, Leganés, Spain, Professor Jose M. Torralba,
[email protected]. Current work on stainless, titanium, superalloys, and bronze. Universidad de los Andes, Bogotá, Columbia, Professor Jairo A. Escobar Gutiérrez,
[email protected]. Emphasis on plasma processing of titanium, cemented carbides, and stainless steels. Univesité de Franche-Comte, ENSMM, Besançon, France, Professor JeanClaude Gelin,
[email protected] and Dr. Thierry Barrière,
[email protected]. Simulation of PIM processes with attention to medical implants. University of Limerick, Limerick, Ireland, Maurice Collins, Maurice.collins@ulie. Use of cyanoacrylates as an alternative binder for medical and automotive applications. University of Science and Technology Beijing, Beijing, China, Professor Xuanhui Qu,
[email protected]. Broad activities in support of advanced materials. University of Technology PETRONAS, Bandar Seri Iskandar, Perak, Malaysia, Professor Faiz Ahmad,
[email protected]. Working on PIM composites. Yeungnam University, Gyeongsan, Korea, Professor Eung Ryul Baek,
[email protected],kr. PIM of stainless steels with supporting simulation software. Centers Advanced Materials Research Center, Kulim, Malaysia, Dr. Rosdi Ibrahim,
[email protected]. Metallic materials with focus on all aspects of PIM process.
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
AET, Tolmin, Slovenia, Stojana Veskovi˘c,
[email protected]. Ceramic injection molding with focus on feedstock development. Agency for Defense Development, Daejeon, Korea, Dr. Sung Ho Lee,
[email protected]. Agency with focus on military developments. Austrian Research Centers, Seibersdof, Austria, Dr. Rudolf Zauner,
[email protected]. Collaborative program funded by government and industry. Central Mechanical Engineering Research Institute, Durgapur, India, Sudip Kumar Samanta,
[email protected]. Supports simulation and process development needs such as in titanium. Forschungszentrum Karlsruhe, Eggenstein-Leopoldshafen, Germany, Dr. Volker Piotter,
[email protected]. Leading program in microminiature PIM R&D. Jozef Stefan Institute, Ljubljana, Solvenia, Dr. Drago Torkar, drago.torkar@ ijs.si. Focus on low-pressure molding of ceramics. Korea Institute of Machinery and Materials, Changwon, Korea, Dr. Jae-Ho Jeon,
[email protected]. Industry–government laboratory focused on piezoceramics and microminiature components. National Metal and Materials Technology Center, Pathumthani, Thailand, Dr. Anchalee Manonukul,
[email protected]. Extending casting computer models to PIM . Pacific Northwest National Laboratory (Battelle), Richland, WA, U.S., Eric Nyberg,
[email protected]. Focus on processing of titanium and tungsten. Tubitak Marmara Research Center, Kocaeli, Turkey, Dr. Halil I. Bakan,
[email protected]. Government program on wide variety of materials with attention to microminiature components. Industry (some companies requested not to be cited in tabulation) Acelent Technologies, Singapore, Lye King Tan,
[email protected]. Support of high-volume production for electronic and medical fields. BASF Aktiengesellschaft, Luwdigshafen, Germany, Dr. Martin Bloemacher,
[email protected]. Feedstock supplier focused on developing new applications in PIM. Bestner, Sungnam-city, Korea, Dr. Tae Shik Yoon,
[email protected] Focus on developing novel piezoelectric components for lighting industry. CM Furnaces, Bloomfield, NJ, U.S., Donald Whychell, dwhychell@ cmfurnaces.com. Contract R&D with focus on thermal cycles and sintering furnaces. CetaTech, Sacheon, Korea, Dr. Young-Sam Kwon,
[email protected]. Software for PIM with maturation into production of novel materials and devices. CoorsTek, Golden, CO, U.S., Holt Simmons,
[email protected]. Ceramic injection molding with emphasis on alumina and zirconia. DSH Technologies, Cedar Grove, NJ, U.S., Dr. Satyajit Banerjee, sbanerjee@ dshtech.com. Contract R&D in support of thermal cycle (debind, sinter, heat treat) development. Porite Taiwan, Chunan, Miaoli, Taiwan, Simon Shong,
[email protected]. Program supports one of the larger PIM houses with core focus on metals. SolidMicron Technologies, Dr. Dunstan Peiris,
[email protected]. Multiple materials, assembly in sintering, and microminiature components. Taiwan Powder Technologies, Taoyuan, Taiwan, Y. C. Lu,
[email protected]. Converting R&D into applications in vehicles, especially stainless steels.
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countries. Each group’s confidential productivity report was used to determine the relative contributions to the field. This showed that the top 20% of the sites contributed half of the output, and the top 40% contributed 70% of the output; Figure 5 plots the distribution in outputs. Statistical analysis showed no difference in productivity with respect to academe, research centers, or industrial laboratories (correlation coefficient 0.0001).
Figure 5. Productivity for the global PIM R&D community. Productivity is based on number of patents, number of papers in 2006, average publication rate over the previous five years, number of presentations (divided by 5), conference publications (divided by 3), and number of full-time personnel
TABLE VI. STATISTICAL PROFILE OF INDUSTRY, RESEARCH CENTER, AND UNIVERSITY PIM R&D CLUSTERS Typical PIM R&D Group
Industry
Center
University
Number of senior researchers Number of students Installed equipment value ($)
3 1 1,800,000
4 3 410,000
2 3 450,000
2 1 6 1 4
1 1 14 3 5
1 3 15 3 4
550,000 310,000 48* 21
600,000 290,000 40 10
250,000 165,000 22 16
Typical Output Metrics Number of patents per year Number of journal papers (2006) Number of publications (past 5 years) Number of conference papers (2006) Number of presentations per year Plans for 2007 Capital equipment budget ($) Operating budget ($) Portion of budget from companies (%) Planned growth versus 2006 (%)
*Excludes self-funded PIM R&D for “industry” category
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The planned PIM R&D budgets for 2007 totaled $26 million, about a $2 million increase over 2006. There are geographic differences based on labor costs, yet Table VI shows what a typical PIM R&D cluster looks like. The standard deviation in these attributes is large, often about the size of the mean value. For example, a few centers have capital budgets over $1 million for 2007 which distorts the average. Some of the groups are growing and others are in decline! The individual planned growth rates ranged from -5% to 50%. Key Researchers The PIM literature is dominated by about a dozen groups. Some of the early efforts were productive and contributed significantly to development of the field. Table VII lists key participants, based on publications and their current countries, if they are still active. Of the publications through 2006, this group of 22 researchers provided nearly 30% of the total output. As with many technical fields, the movement of researchers leads to some confusion on affiliation (for example, Zhang was born and raised in China, worked in Singapore, and is currently employed in the U.S.). Even so, the profile on top researchers is consistent with the other statistics reported in this study. TABLE VII. ALPHABETICAL LISTING OF KEY RESEARCHERS IN PIM R&D, BASED ON PUBLICATIONS Atre, Sundar V. Bose, Animesh Chung, Chan I. Edirsinghe, Mohammed J Evans, James G.R. Gelin, Jean-Claude German, Randall M. Heaney, Donald Hens, Karl F. Hwang, Kuen Shyang Lee, Deyoung Lin, Shun-Tian Loh, Ngiap Hiang Miura, Hideshi Mutsuddy, Beebus C. Petzoldt, Frank Piotter, Volker Rhee, Byung O. Tan, Lye King Torralba, Jose Manuel Zauner, Rudolf Zhang, Haorong
U.S. U.S. U.S. U.K. U.K. France U.S. U.S. U.S. Taiwan U.S. Taiwan Singapore Japan U.S. Germany Germany Korea Singapore Spain Austria U.S.
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R&D IN SUPPORT OF POWDER INJECTION MOLDING: STATUS AND PROJECTIONS
Impact Factor The academic community has moved beyond simple counting of publications and now uses impact factors to monitor if a publication is relevant. Accordingly, most publishers seek papers that will be cited frequently to improve their impact rating. With respect to PIM, the largest impact is from the early books. The highest impact publications are listed in Table VIII in decreasing frequency of citations. Note that several of these publications reflect the same list of authors as given in Table VII. Materials The same database and survey resources were used to identify the most studied materials. By far, stainless steels dominate the PIM field, with 28% of all publications including information on these alloys. Indeed, ferrous materials (stainless steels, steels, pure iron, and tool steels) account for 60% of the PIM output. Table IX lists materials in order of decreasing emphasis. At the bottom of the list the activity is only 5% of that corresponding to the top. Alumina is the most important ceramic, followed by silicon nitride. Other materials of recent emphasis are composites, copper, hydroxyapatite, molybdenum, nickel, and silicon carbide. The most intense current research is still on stainless steels, followed, in order, by titanium and titanium alloys, tungsten alloys, alumina, cemented carbides and related cermets, iron and steel, and zirconia. Also, a few groups cited efforts on aluminum, silicon carbide, silicon nitride, soft magnetic materials, tool steels, and zirconia. Based on these research trends, significant commercial growth will occur in titanium and tungsten alloys. CURRENT PROFILE OF PIM R&D Although the PIM R&D community is largely upbeat, with overall average growth in equipment and operating budgets at 15% for 2007 compared with 2006, about a third of the research leaders were pessimistic for 2007. Plots of PIM R&D paper production show a plateau for the past several years following a rapid climb 20 years ago. Statistical analysis of the survey results shows some obvious facts—groups that have more researchers have higher budgets and produce more publications, conference presentations, and patents. More interesting is the fact that a higher level of industry support correlates with more Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
TABLE VIII. IMPACT FACTOR PUBLICATIONS IN PIM, IN DECREASING FREQUENCY OF CITATIONS 1. R.M. German, Powder Injection Molding, Metal Powder Industries Federation, Princeton, NJ, 1990. 2. R.M. German, “Theory of Thermal Debinding,” International Journal of Powder Metallurgy, 1987, vol. 23, pp. 237–245. 3. O.O. Omatete, M.A. Janney and R.H. Strehlow, “Gelcasting—A New Ceramic Forming Process,” Ceramic Bulletin, 1991, vol. 70, pp. 1,641–1,649. 4. R.M. German and A. Bose, Injection Molding of Metals and Ceramics, Metal Powder Industries Federation, Princeton, NJ, 1997. 5. R. M. German, K.F. Hens and S.T. Lin, “Key Issues in Powder Injection Molding,” Ceramic Bulletin, 1991, vol. 70, pp. 1,294–1,302. 6. A.J. Fanelli, R.D. Silvers, W.S. Frei, J.V. Burlew and G.B. Marsh, “New Aqueous Injection Molding Process for Ceramic Powders,” Journal American Ceramic Society, 1989, vol. 72, pp. 1,833–1,836. 7. B. Yang and R.M. German, “Powder Injection Molding and Infiltration Sintering of Superfine Grain W-Cu,” International Journal of Powder Metallurgy, 1997, vol. 33, no. 4, pp. 55–63. 8. B.C. Mutsuddy, “Ceramic Injection Moulding,” Industrial Ceramics, 1989, no. 839, pp. 436–441. 9. R. Knitter, D. Goehring, P. Risthaus and J. Hausselt, “Microfabrication of Ceramic Microreactors,” Microsystem Technologies, 2001, vol. 7, no. 3, pp. 85–90. 10. L.A. Najmi and D. Lee, “Modeling of Mold Filling Process for Powder Injection Molding”, Polymer Engineering and Science, 1991, vol. 31, pp. 1,137–1,148. 11. J.C. Kim, S.S. Ryu, H. Lee and I.H. Moon, “Metal Injection Molding of Nanostructured W-Cu Composite Powder,” International Journal of Powder Metallurgy, 1999, vol. 35, no. 4, pp. 47–55. TABLE IX. COMPARISON OF MATERIALS IN PIM R&D IN TERMS OF PAST PUBLICATIONS AND CURRENT ACTIVITIES Material Stainless steel Steel Iron, nickel–iron Alumina Tungsten alloys Silicon nitride Titanium Tool steel Cemented carbide and cermet Zirconia Others
Publications (%) Current Activity (%) 28 15 13 12 5 4 4 4 4 4 7
25 7 7 10 10 2 17 2 8 6 6
publications and presentations. One can debate the cause–effect relation here, since groups that publish and present more frequently are probably easier for industry to identify. Curiously, the only factor that correlates with R&D funding growth is the number of conference papers; again, the visible programs are growing.
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FUTURE ACTIVITIES The high cost of training experts in a field such as PIM discourages expansion of the R&D workforce. In the U.S. it takes over $400,000 in support to graduate a PhD in engineering. The university education model links graduate education and research, so any downturn in R&D funding reduces the future labor pool. There is a problem arising with outsourcing2,37 and from the statistics gathered here it is clear PIM R&D is undergoing the same trend. A decrease in the manufacturing base in the U.S. is coupled to a migration of PIM R&D to Asia. With respect to the product life cycle, the highest R&D investment is at the inflection point in the sales curve. Since traditional PIM has passed through this inflection, R&D funds are more difficult to secure for traditional topics such as stainless steels. The good news is that academic researchers are adept at leveraging their funds, but with commercial migration to low-cost regions industrial R&D funding is also moving to new geographic regions. The PIM R&D community is sensitive to commercial trends. As PIM has shifted to Asia, likewise PIM R&D has moved to Asia. Due to a surge in growth, a few large PIM R&D programs have emerged in China, Japan, Korea, Singapore, and Taiwan. However, several strong actors remain in Austria, France, Germany, and the U.S. Digging into the activity profile shows a trend toward three topics: (1) computer simulation, (2) smaller powders, and (3) microminiature components. Some favorite materials are stainless steel and titanium. The most frequently cited applications are in medical or biomedical systems and electronics or computer components. The typical PIM R&D group consists of two to four senior researchers, complimented by a few support staff and students. In the U.S., funding for academic R&D is shifting to leading-edge topics—the three “o’s” of bio, nano, and info. Because of such shifts, academic support for PIM R&D is likewise being refocused to integrate nano and bio into PIM, providing some of the best research funding opportunities. CONCLUSIONS This effort is focused on providing a first tracking of the PIM R&D effort. The data captured provide an important benchmark for the research community by showing current topics, materials,
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equipment acquisitions, and some emerging opportunities. The future directions for PIM R&D have been assembled from several inputs. Cost reduction and process optimization are dominant issues in industrial PIM R&D. Typically these topics are best handled in a production environment, so they are addressed by university-based research programs. On the other hand, PIM R&D is moving into the bio, nano, and info fields. Accordingly, the new directions for PIM R&D will be associated with intersections of four topics: Computer simulations Medical devices Microminiature structures Titanium and biocompatibility ACKNOWLEDGMENTS This study relied on input from a large number of collaborators and my deep appreciation is extended to the nearly 100 peers who provided written comments and input. Special thanks go to Professors Fehim Findik, Kuen Shyang Hwang, Hideshi Miura, and Seong Jin Park for their personal involvement in the data collection. Additionally, many researchers provided data profiles on the PIM R&D community; without them the report would be of limited scope. REFERENCES 1. G.A. Moore, Crossing the Chasm, Harper Collins, New York, NY, 1991. 2. J. Duga and T. Studt, “2007 Global R&D Report”, R&D Magazine, 2006, vol. 48, no. 9, pp. G1–G10. 3. P.S. Seoerstrom, T.C.A. Anant and E. Dinopoulios, “A Schumperterian Model of the Product Life Cycle”, American Economic Review, 1990, vol. 80, pp. 1,077–1,091. 4. L.F. Pease, “A Perspective on the Markets and Technology for Injection Molded Metal Powder and Ceramic Parts”, Int. J. Powder Metall., 1986, vol. 22, no.3, pp. 177–184. 5. A. Nyce, Injection Molded Metal, Ceramic, Cermet, and Cemented Carbide Powders, Gorham Advanced Materials Institute, Gorham, ME, 1988. 6. L.F. Pease, “Metal Injection Molding: The Incubation is Over”, Int. J. Powder Metall., 1988, vol. 24, no. 2, pp. 123–127. 7. B.C. Mutsuddy, “An Overview of the Markets and Technology for Injection Molded Ceramics and Cemented Carbide”, Proc. Third International Conference on Injection Molding of Ceramics, Cemented Carbides and Metals, Gorham Advanced Materials Institute, Gorham, ME, 1988. 8. L.F. Pease, “Overview of MIM in North America, World Market Size and Forecast”, Development and Applications of Advanced Ceramics & P/M Materials, Proc. International New Business and High-Tech Research Conference, 1989, Jyvaskyla, Finland, pp. 1–56.
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9. A.C. Nyce, “Markets, Forecasts, Business Opportunities and Applications for MIM, CIM and CCIM”, Proc. Business Opportunities in the Emerging Markets for Injection Molded Metal, Ceramic, and Cemented Carbide Parts Conference, Gorham Advanced Materials Institute, Gorham, ME, 1989. 10. G. Will, “MIM and CCIM Injection Molding Markets in Europe”, ibid. reference no. 9. 11. L.F. Pease, “Overview of MIM in North America, World Market Size and Forecast,” Metal Powder Report, 1990, vol. 45, no. 5, pp. 345–354. 12. Powder Injection Molding Symposium—1992, Edited by P.H. Booker, J. Gaspervich and R.M. German, Metal Powder Industries Federation, Princeton, NJ, 1992. 13. Proc. of 1993 Powder Metallurgy World Congress, edited by Y. Bando and K. Kosuge, Japan Society of Powder and Powder Metallurgy, Kyoto, Japan, 1993. 14. E.R. Andreotti, L. Pease and A.C. Nyce, “Present Status and Future Prospects for MIM”, Proc. Markets for Injection Molded Metal, Ceramic, and Hardmetal Parts Conference, Gorham Advanced Materials Institute, Gorham, ME, 1994. 15. Proceedings PM’94, Powder Metallurgy World Congress, European Powder Metallurgy Association, Shrewsbury, U.K., 1994. 16. R.M. Ger man, “Growth and Industry Structure in Injection Molding Metal Powders”, Proc. World Powder Metallurgy Markets 1997 Conference, Gorham Advanced Materials, Gorham, ME, 1997. 17. R.P. Reed, “MIM in the 21st Century”, ibid. reference no. 16. 18. Powder Injection Moulding, Proc. First European Symposium on Powder Injection Moulding, European Powder Metallurgy Association, Shrewsbury, U.K., 1997. 19. R.M. German and R.G. Cornwall, The Powder Injection Molding Industry, an Industry and Market Report, Innovative Material Solutions, State College, PA, 1997. 20. First Japan-Korea Workshop on PIM, edited by S. Ahn and N.J. Kim, Research Institute of Industrial Science and Technology, Pohang, Kyungbuk, Korea, 1997. 21. R.M. German and R.G. Cornwall, “Worldwide Market and Technology for Powder Injection Molding”, Int. J. Powder Metall., 1997, vol. 33, no. 4, pp. 23–27. 22. Proc. 1998 PM World Congress, European Powder Metallurgy Association, Shrewsbury, UK, 1998. 23. C. Christensen and B. Baird, Vallourec’s Venture into Metal Injection Molding, Case 9-697-001, Harvard Business School, Harvard University, Boston, MA, 1998. 24. R.M. German and R.G. Cornwall, Powder Injection Molding
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25.
26.
27.
28. 29.
30.
31. 32.
33.
34.
35.
36.
37.
in the Year 2000, an Industry and Market Report, Innovative Material Solutions, State College, PA, 2000. R. Howells, “The Metal Injection Moulding Market from the Viewpoint of the Powder Producer”, Second European Symposium on Powder Injection Moulding, European Powder Metallurgy Association, Shrewsbury, UK, 2000, pp. 3–9. Proc. 2000 Powder Metallurgy World Congress, edited by K. Kosuge and H. Nagai, Japan Society of Powder and Powder Metallurgy, Kyoto, Japan, 2000. R.G. Cornwall and R.M. German, “An Analysis of the Powder Injection Molding Industry Global Market”, Advances in Powder Metallurgy and Particulate Materials— 2001, compiled by W.B. Eisen and S. Kassam, Metal Powder Industries Federation, Princeton, NJ, 2001, part 4, pp. 11–16. B. Williams, “A $2 Billion Business?”, Metal Powder Report, 2002, vol. 57, no. 3, pp. 6–7. Proc. PM2004 Powder Metallurgy World Congress, European Powder Metallurgy Association, Shrewsbury, UK, 2004. R.G. Cornwall and R.M. German, “Think Bigger! The Future is Bright for MIM”, Metal Powder Report, 2004, vol. 59, no. 11, pp. 8–11. M. Rajan, Metal Injection Molding, Report RGB-306, Business Communications Co., Norwalk, CT, 2005. R.G. Cornwall and R.M. German, “World Markets and Technologies—PIM Status Update”, Proc. PIM 2005 International Conference on the Powder Injection Molding of Metals, Ceramics, and Carbides, Innovative Material Solutions, State College, PA, 2005. B. Williams, “PM Growth in Asia Becomes Clear at Busan”, Metal Powder Report, 2006, vol. 61, no. 10, pp. 6–10. J.E. Hirsch, “An Index to Quantify an Individual’s Scientific Research Output”, Proc. National Academy of Sciences of the United States of America, 2005, vol. 102, pp. 16,569–16,572. B. Smarslok and R.M. German, “Identification of Design Parameters in Metal Powder Injection Molding”, Journal of Advanced Materials, 2005, vol. 37, no. 4, pp. 3–11. R.M. German, User’s Guide to Powder Injection Molding— Designs and Applications, Innovative Material Solutions, State College, PA, 2003. Rising above the Gathering Storm, Committee on Science, Engineering & Public Policy, (N.R. Augustine, chair), National Academies of Science, Engineering & Medicine, Washington, DC, 2005. ijpm
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RESEARCH & DEVELOPMENT
SINTERING RESPONSE & MICROSTRUCTURAL EVOLUTION OF AN Al-Cu-Mg-Si PREMIX José M. Martín* and Francisco Castro**
INTRODUCTION Aluminum alloys exhibit an attractive combination of properties for the production of lightweight powder metallurgy (PM) components in a wide range of applications.1–10 In aerospace, several aluminum alloys have been processed by PM, followed by mechanical working.6–9,11 The economic production of aluminum parts by conventional pressing and sintering is gaining interest relative to the automotive industry.6,12–18 Due to the thermodynamic stability of the thin oxide layer covering the aluminum particles, any reducing atmosphere cannot remove it at normal sintering temperatures. This oxide layer acts as a diffusion barrier and successful sintering leading to the formation of strong, metallic contact areas can only be achieved by using liquid phases to penetrate the oxide film via the discontinuities created during cold pressing,19–23 thus promoting material transport. Other possibilities for the formation of additional discontinuities during the sintering cycle have been described.23–24 Extensive research has been conducted on the sinterability of binary19–21,24–29 and more complex22,28,30–38 aluminum alloys. These studies embrace the influence of sintering parameters (such as atmosphere, temperature, heating rate, particle size, and the type of metallic additions) on the mechanical properties and dimensional stability of the compacts. Liquids in these systems may form by melting of the additives, or through a eutectic reaction between aluminum and the added metallic powders. Although there are differing viewpoints on the optimal way to introduce alloying elements, the use of prealloyed powders represents an obvious alternative and more research is needed in this area. At present, its utilization has been considered unattractive because of difficulties in compaction,22 notwithstanding the advantages related to the dimensional stability of the compacts.21 Other authors, working primarily on binary alloys,19–20,23,28–29,39 have performed metallographic analyses on PM alloys subjected to different sintering conditions. A limited number of studies have focused on microstructural events occurring during the sintering cycle in more complex alloys.32,34,36
The sintering behavior of a powder premix (Al-4.4 w/o Cu-0.5 w/o Mg-0.7 w/o Si) has been studied. Reactions occurring during liquid-phase sintering of this alloy have been identified by means of differential scanning calorimetry (DSC), dilatometry, sintering experiments, and microstructural analysis, including energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). The first reaction observed is the formation of aluminum– magnesium liquid at ~450°C. This reaction is followed by other reactions at 505°C and 550°C which are related to the incorporation of copper into the liquid phase at the same time that magnesium, silicon, and copper diffuse into the solid aluminum particles. Swelling of the powder compact during the initial sintering stage is related to chemical homogenization of the alloy, and to spreading of the liquid phase. Following a complex sintering cycle with a slow heating rate after de-waxing (2°C/min), a first holding step for 20 min at 570°C in vacuum, and a second holding step at 590°C for 20 min in nitrogen, a final density ~98% of the pore-free level was obtained. Tensile properties and hardness of the alloy were determined in the assintered and heat-treated (T4 and T6) conditions. Optimal results were: ultimate tensile strength 388 ± 26 MPa and elongation to fracture 0.26%–0.73% in the T6 condition.
*Staff researcher, **Head of the Powder Consolidation Group, Department of Materials, CEIT and TECNUN, P° de Manuel Lardizabal 15, 20018, San Sebastián, Spain; E-mail:
[email protected]
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We present the results of an investigation that focused on microstructural evolution during sintering using a commercially available heat-treatable 2xxx series aluminum alloy premix. The role of each element in the powder premix has been assessed. Specimens were quenched at specific stages of the sintering cycle, based on changes recorded by DSC and dilatometry. The objective of the study was to monitor the microstructural changes produced during development of the alloy from the powder constituents . Particular attention was given to the formation of liquids, their transition from a transient to a persistent entity, and to their effects on both the final microstructure of the alloy and attendant dimensional changes. EXPERIMENTAL PROCEDURE Commercially available aluminum powder was used in the present study. The characteristics of the premix, in the as-received condition, are summarized in Table I, based on the technical data sheet provided by the supplier. Green compacts were fabricated by the uniaxial cold pressing of powder samples of a fixed mass in a rigid steel die. A compaction curve relating green density to the applied pressure (up to 600 MPa) was established using cylindrical compacts 16 mm dia. × ~5 mm high. Changes taking place in the compact during the heating cycle were monitored by means of dilatometry and DSC experiments carried out under a nitrogen atmosphere. The compacts were previously dewaxed at 410°C for 20 min. Dilatometry was used to record dimensional changes of the green compacts up to a temperature of 600°C and at heating rates of 5, 10, and 20°C/min. DSC results provided information on the internal energy changes taking place at temperatures up to 680°C for heating rates from 2°C to 20°C/min.
Interrupted sintering experiments involving direct water quenching from specific temperatures in a heating ramp were performed to follow the microstructural development of the alloy during sintering. Cylindrical compacts (16 mm dia. × ~5 mm high) pressed at 400 MPa and having a green density of 2.62 ± 0.01 g/cm3 (94.2 ± 0.5% porefree density), were dewaxed at 410°C for 20 min and sintered under a nitrogen atmosphere utilizing heating rates of 2°C/min and 10°C/min. The sintered compacts were subsequently removed from the furnace at temperatures between 410°C and 590°C, and allowed to fall into the quenching media in <2 s. Compacts of the same geometry, pressed and dewaxed under identical conditions, were sintered at high temperature in a controlled-atmosphere furnace following the thermal regime illustrated in Figure 1. Sintering was carried out under vacuum until the end of the first holding step, and subsequently in a nitrogen atmosphere. The sintering temperature for the second holding step (T s ) ranged from 590°C to 630°C. A minimum of three specimens were sintered per cycle. After sintering, some of the compacts were subjected to T4 or T6 aging treatments in order to develop their full mechanical properties. In both cases the solution treatment was carried out at 505°C for 30 min in nitrogen, followed by water quenching. To complete the T4 treatment, the compacts were naturally aged for 4 days. For the T6 condition the compacts were aged at 160ºC for 16 h. For microstructural analysis specimens were polished (0.04 µm finish) using colloidal silica and observed directly in a scanning electron micro-
TABLE I. PREMIX CHARACTERISTICS (ECKA ALUMIX 123) Chemical Composition (w/o) Al-4.4 w/o Cu-0.5 w/o Mg-0.7 w/o Si-1.5 w/o Microwax C. Particle-Size Distribution by Sieve Analysis (w/o) <45 µm 45–63 µm 63–100 µm 100–200 µm >200 µm 10 15 43 30 2 Apparent Density (g/cm3) 0.95–1.05
Tap Density (g/cm3) 1.25–1.35
* At a green density of 2.56 g/cm3
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Flow Rate Green Strength (s/50 g; 5.0 mm) (N/mm2)* <30 >8.0 Figure 1. Unconventional sintering cycle used in this study
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scope (SEM) or optical microscope (OM) without etching or any other additional surface preparation. Identification of the major intergranular phase was carried out utilizing XRD. Room-temperature mechanical properties of the alloys were evaluated in the as-sintered and in the T4 and T6 conditions. Hardness tests (HRF) and tensile tests (MPIF Standard No. 10)40 were performed on flat unmachined specimens,40 three specimens for each condition were used in the tensile tests. The density of the green compacts was determined from mass and geometry, while the density of the sintered samples was measured by the immersion method. RESULTS AND DISCUSSION As seen in Table I, the premix contains 1.5 w/o Microwax C to aid in compaction. Therefore, the green density reported in Figure 2 includes the influence of this organic binder (the pore-free density of the powder mixture is 2.78 g/cm 3 ). As observed in Figure 2, the curve shows the expected behavior with densities above 90% of the pore-free level for compaction pressures >250 MPa. Based on experimental observations on debinding and final density after sintering, 400 MPa was selected as the optimum pressure for the remainder of the study. At this pressure, a compaction ratio of about 2.62 was measured, since the average apparent density of the powder (Table I), is ~1.0 g/cm3. It is observed that between 400 MPa and 600 MPa minor increases in density occur. This is
Figure 2. Compaction curve for Ecka Alumix 123 premix compared with supplier’s data (Eckart-Dörn) and literature 30
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in qualitative disagreement with the compressibility curves obtained in previous work, which are used in Figure 2 for comparison purposes. Since the premix consisted of aluminum particles with other additions, lightly polished powder compacts were examined by OM and SEM, in order to derive a visual appreciation for the distribution of the different elements/compounds in the premix prior to sintering. In general, the green compact can be considered to be homogeneous, as seen by the distribution of the copper particles, Figure 3(a). However, local heterogeneities are expected at the location of the added particles containing the differing elements required to achieve the intended overall composition of the alloy (Figure 3(b)). From these observations it is seen that, apart from the electrolytic copper particles (~3 to 60 µm), silicon appears to have been added as an atomized aluminum–silicon alloy. In contrast, magnesium is present as a master alloy, or an intermetallic compound, in the form of angular and cracked particles as a result of mechanical grinding. As observed in Figure 3(c) these particles have sizes between 20 µm and 60µm. Figure 3(c) also shows that the interdendritic space inside the aluminum particles contains a relatively high concentration of a segregated impurity with an atomic number higher than that of aluminum. It is thought that this impurity is iron, which is commonly found in airatomized aluminum powders in amounts up to 1,500 ppm.2,14 EDS analyses carried out on these particles gave approximate compositions of Al12.5 w/o Si and Al-50 w/o Mg, respectively. Several DSC and dilatometry experiments were carried out in order to arrive at an improved insight into the events occurring as a function of time and temperature. Figure 4 shows a representative DSC trace up to 600°C in a nitrogen atmosphere; this reveals the complexity of this alloy system, as evidenced by the large number of endothermic and exothermic “peaks” over the temperature range of interest. The most relevant information obtained is the temperature at which several reactions take place. The earliest events, evidenced by the region of the two peaks below 460°C in Figure 4, are related to a reaction starting at 449°C, followed by a second endothermic reaction at about 457°C. These reactions appear to be associated with the melting of magnesium-containing compounds. However, in light of the phase diagram and uncer-
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first “peak” at ~449°C, possibilities are fusion of the β-phase (Mg2Al3 or Mg5Al8) or, alternatively, formation of aluminum–magnesium eutectic liquid on the aluminum-rich side of the diagram. As heating continues, there is a tendency for the system to reach its equilibrium composition by diffusion of magnesium toward the liquid, and also into neighboring solid aluminum particles. In this way the composition of the liquid evolves along the liquidus line. Melting of the γ-phase (Al12Mg17) takes place and is responsible for the second “peak” at about 457°C, and “pure” solid aluminum reaches a composition within the solid-solution field accompanied by enrichment in magnesium towards the interface. Based on Figure 5, the cited arguments are
Figure 4. DSC trace at a heating rate of 10°C/min up to 600°C in nitrogen atmosphere
Figure 3. Representative microstructures of green compact pressed at 400 MPa. (a) SEM backscattered electron image showing general distribution of copper particles (white), (b) OM image showing different alloying particles, and (c) SEM backscattered electron image showing different particles and impurities at interdendritic boundaries inside alumimum particles
tainty in the determination of the exact temperatures in the calorimeter, these “peaks” are most likely associated to the formation of the first aluminum–magnesium liquids. Therefore, for the
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Figure 5. Diffusion profile at interface between aluminum and Al-50 w/o Mg particles after debinding at 410°C for 20 min in nitrogen atmosphere
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supported by the diffusion profile at the interface between an aluminum and an Al-50 w/o Mg particle quenched after dewaxing. This figure confirms that the interdiffusion of aluminum and magnesium atoms is limited across neighboring particle interfaces; it extends for a maximum distance ~2 µm on each side of the inter face. However, this may lead to the formation of the AlMg β-phase, or similar compositions, in the vicinity of the aluminum side of the interface, and finally to the formation of Al12Mg17 on the side of the magnesium-rich particle. Alternatively, these phases may have formed during atomization of the Al-50 w/o Mg powder. As observed in Figure 6, which shows the dilatometry trace obtained up to 600°C, the aforementioned reactions occur, accompanied by swelling starting at ~445°C– 450°C. This may be due to the preferential dissolution of magnesium into the aluminum in neighboring particles. 22,29,41 This argument finds support in relation to the microstructural observations, as illustrated in Figure 7, which corresponds to a specimen quenched from 475°C. This micrograph shows an Al-50 w/o Mg particle which appears to be leaving a pore in its place as migration of magnesium atoms takes place into one of the aluminum particles next to it. The formation of this aluminum–magnesium solid solution, together with the creation of porosity at the original place occupied by the Al-50 w/o Mg particle, is responsible for the swelling. This argument is also consistent with previous observations by Savitskii41 on the sintering behavior of the aluminum–magnesium alloy system. Additionally,
Figure 6. Dilatometer trace at a heating rate of 5°C/min up to 600°C in nitrogen atmosphere
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
and based on EDS measurements carried out on the specimen of Figure 7, the diffusion of magnesium has taken place over a distance ~30 µm into the aluminum particle; the latter appears to exhibit an adequate contact interface with the magnesium particle. In contrast, no magnesium was found in the aluminum particle at the left of the micrograph. As heating continues toward the sintering temperature, the DSC trace in Figure 4 shows exothermic behavior, along with several endothermic and exothermic peaks between 457°C and ~505°C. This effect is related to reactions taking place within this temperature range, and may include: (a) the formation of additional amounts of liquid by the melting of magnesium-containing aluminum particles; (b) the dissolution of aluminum, copper, and silicon in this liquid; and (c) the diffusion of magnesium and copper atoms into neighboring solid aluminum particles, plus the for mation of inter metallic compounds. Subsequently, as indicated by the DSC trace in Figure 4, at ~505ºC an endothermic reaction occurs, attributed to the formation of a liquid phase, following the reaction: Al + CuAl2 + CuMgAl2 → Liq. (507°C)
(1)
Alternatively, when silicon is present, the reaction is: Al + CuAl2 + CuMgAl2 + Mg2Si → Liq. (500°C) (2) Al + CuAl2 + Si + Cu2Mg8Si6Al5 → Liq. (507°C) (3) As reported in the literature1 these reactions take place at 507°C, 500°C, and 507°C, respec-
Figure 7. Representative microstructure of compact water quenched from 475°C after heating at 2°C/min in nitrogen atmosphere. SEM secondary electron image. EDS analyses on marked spots: (a) ~100 w/o Al, (b) ~74 w/o Al-4 w/o Cu-22 w/o Mg, and (c) ~90 w/o Al-10 w/o Mg
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tively, which are in excellent agreement with the temperatures indicated by the DSC trace. These reactions, starting at ~505°C, continue up to ~550°C. Microstructural observations on the specimens quenched from 525°C (Figures 8 and 9) identified the active role played by copper, silicon, and magnesium in these events. Firstly, some Al-12.5 w/o Si particles have dissolved in the transient liquid and the solid aluminum and then reacted to form Mg 2Si and Cu 2Mg 8Si 6Al 5 compounds. Secondly, the remaining magnesium particles have, most likely, formed CuMgAl2 with the copper particles in contact with them. These intermetallic compounds intervene in the formation of transient liquids after reactions (1) to (3). Thirdly, elements contained in the liquids may
Figure 8. Representative microstructure of sample quenched in water from 525°C after heating at 2°C/min in nitrogen atmosphere. SEM backscattered image. EDS analyses on marked spots: (a) ~95 w/o (Al+Mg)-5 w/o Cu and (b) ~100 w/o (Al+Mg)
Figure 9. Representative microstructure of sample quenched in water from 525°C after heating at 2°C/min in nitrogen atmosphere. SEM backscattered image. Arrows delineate unaltered copper particles
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diffuse into the surrounding aluminum matrix, leaving behind large pores, which are evident in Figure 8, resulting in swelling starting at ~500°C–505°C, as confirmed by the dilatometer trace (Figure 6). Finally, since silicon and magnesium have similar diffusion coefficients in solid aluminum, and are correspondingly higher than the diffusion coefficient of copper in aluminum,42 these elements are more evenly distributed in the microstructure while copper is distributed heterogeneously, as evidenced by the appearance of the white areas in the micrographs of Figure 8. It is also seen that not all the copper particles have participated in this process since several remain unaltered. Only those particles in contact with, or close to, the magnesium-rich liquid are dissolved, leading to the diffusion of copper atoms from the liquid. This observation is more evident in Figure 9, taken at a higher magnification, where unaffected copper particles are delineated. A similar situation is observed for the Al-12 w/o Si particles. From the microstructures it is concluded that the particles in contact with the liquid have dissolved, thus allowing for the incorporation of silicon. However, as illustrated by Figure 10, the particles located away from the liquid areas are present at 525°C and have become globularized during heating. It is apparent that, after reaching a temperature ~570°C, when the amount of liquid is important, these particles are no longer observed. In summary, although the individual reactions described take place over specific temperature ranges, the overall behavior of the alloy during heating from ~500°C is endothermic. This means that this part of the process is governed by the presence of a liquid whose composition and volume fraction evolve with temperature, until complete melting of the alloy occurs if the temperature is >646°C (based on DSC measurements) or 642°C (based on Thermo-Calc43 calculations performed with the COST 507 database44–46). Since general melting is not of interest during sintering, a description of the microstructural progress between 550°C and the sintering temperature is necessary in order to understand how the final microstructure of the alloy evolves. Figure 4 shows another important endothermic reaction at ~549°C; this reaction corresponds to:1 Al + CuAl2 → Liq. (548ºC)
(4)
This reaction occurs at locations where the copVolume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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per particles far removed from the magnesium particles did not interfere with reactions (1) to (3) due to insufficient concentration of magnesium. This reaction does not appear to result in swelling of the compact, since the amount of liquid present in the system is sufficient to produce shrinkage by normal liquid-phase sintering (LPS) mecha-
nisms. Figure 6 confirms this effect in the form of a change of slope in the dilatometer trace at ~540°C–555°C. At this stage, chemical homogenization of the alloy may be monitored in terms of the microstructures corresponding to specimens quenched from 570°C and 590°C. As observed in Figure 11(a), essentially all the
Figure 10. Representative microstructure showing microstructural evolution of Al-12 w/o Si particles while heating in nitrogen atmosphere to the sintering temperature. OM. (a) green compact, (b) after debinding for 20 min at 410°C, (c) quenched in water from 475°C after heating at 2°C/min, and (d) quenched in water from 525°C after heating at 2°C/min
Figure 11. Representative microstructure corresponding to samples quenched in water after heating at 2°C/min in nitrogen atmosphere. (a) 570°C and (b) 590°C. SEM backscattered images
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copper in the alloy has been incorporated in the microstructure, according to reaction (4), to form permanent aluminum/copper liquid which also contains small amounts of magnesium and silicon. This liquid appears to surround the aluminum grains after quenching. At this point compositional gradients have been smoothed out and the constitution of the alloy is nearing equilibrium. It is noted that intragranular CuAl2 precipitates may also form upon rapid cooling. At 590°C the microstructure contains the same constituents, but with an increasing volume of liquid as the temperature is increased, Figure 11(b). A higher heating rate to 590°C (from 2°C/min to 10°C/min) results in slower homogenization of the alloy, as observed in Figure 12. The cited reactions still take place at the same temperatures but the liquids formed have less time to spread. Also, the alloying elements have less time to diffuse into the aluminum and, in these microstructures, copper is not distributed homogeneously under these conditions (Figure 12). Some of the copper particles are either unaltered or tend to form a liquid (Figure 13). The behavior of this alloy following a conventional sintering cycle under varying conditions of temperature, time, and atmosphere was reported previously.47 Under a nitrogen atmosphere, an optimal combination of sintered density and hardness (2.59 g/cm3 (93% pore-free density) and 60 HRF) was obtained at 590°C for 20 min. Raising the sintering temperature to >590°C led to a small increase in density, but without any increase in hardness, due to grain growth. In contrast, sinter-
Figure 12. Representative microstructure of sample quenched in water from 590°C after heating at 10°C/min in nitrogen atmosphere. SEM backscattered image. EDS analyses on marked spots: (a) ~92 w/o Al-2 w/o Cu-4 w/o Mg-2 w/o Si, and (b) ~100 w/o AL
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ing at 590°C under vacuum resulted in a density of 2.66 g/cm3 (95.7% pore-free density) and a hardness of 69 HRF. This constitutes an attractive improvement in both properties in the as-sintered state. The improvement in sintered density is attributed to the prevention of gas entrapment from the sintering atmosphere.48–49 As a further exploration of the effect of the sintering schedule and atmosphere on properties, the sintering regime illustrated in Figure 1 was utilized. This cycle represents an attempt to minimize distortion of the samples during sintering, assuming the distortion to be associated with the manner in which the liquid appears and spreads between the aluminum particles. Under these conditions, a sintering cycle with a slow heating rate and various holding steps should allow for uniform spreading of the liquid, and hence result in a uniform densification of the sample. The first step is carried out under vacuum in order to prevent gas entrapping in the pores.48–49 Table II presents a summary of the sintered density and hardness values as a function of sintering temperature at the upper holding step (T s ) in Figure 1. It is observed that the final sintered density is the same in all cases, but the hardness drops significantly at 630°C, due to grain growth.47 A set of tensile specimens with a green density of 2.61 ± 0.02 g/cm3 (93.9 ± 0.7% pore-free density) were sintered following this cycle at a temperature Ts of 590°C. After sintering, these samples exhibited a density of 2.745 ± 0.006 g/cm3 (98.7 ± 0.2% pore-free density). Some of these specimens were heat treated to the T4 or T6 condition. The effects of this additional heat treatment on tensile properties are summarized in Table III. These
Figure 13. Representative microstructure of sample quenched in water from 590°C after heating at 10°C/min in nitrogen atmosphere. SEM backscattered image
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property levels are considerably higher than those reported in the technical literature for this alloy14,16,30–31 and are comparable with recently reported values obtained after introducing slight modifications in chemical composition.34 A set of components pressed under industrial conditions (Figure 14) were sintered following the TABLE II. AS-SINTERED DENSITY AND HARDNESS AS A FUNCTION OF SINTERING TEMPERATURE (SINTERING CYCLE IN FIGURE 1) Ts (°C) 590 610 630
Sintered Density (g/cm3) Pore-Free Density (%) 2.72 ± 0.02 2.71 ± 0.02 2.717 ± 0.008
97.8 ± 0.6 97.5 ± 0.6 97.7 ± 0.3
HRF 73.9 ± 8.6 70.0 ± 12.4 59.8 ± 13.5
TABLE III. TENSILE PROPERTIES,YOUNG’S MODULUS AND HARDNESS OF ALLOYS SINTERED AT 590°C (SINTERING CYCLE IN FIGURE 1) Condition As-sintered T4 T6
UTS 0.2% Offset Yield (MPa) (MPa) 225 ± 20 318 ± 11 388 ± 26
152 ± 4 231 ± 6 370 ± 13
Elongation (%)
E (GPa)
HRF
2.9 ± 1.2 4.5 ± 0.6 0.26/0.73
61 ± 18 69 ± 3 71 ± 10
80 ± 4 92 ± 4 97 ± 4
cycle shown in Figure 1. The components were pressed to a green density of 2.52 g/cm3 (90.5% pore-free density) with a uniform external dia. 26.30 ± 0.02 mm from top to bottom. After sintering at 590°C for 20 min, the density increased to 2.66 g/cm3 (95.6% pore-free density) with an assintered hardness of 73 ± 5 HRF. Although the components exhibited a uniform contraction pattern, the as-sintered top and bottom diameter differed from 25.89 ± 0.14 to 25.97 ± 0.12 mm, respectively. These differences could be corrected after a sizing operation that also contributed to a slight increase in the surface hardness, and an improved surface finish. Figure 15 shows a representative microstructure of these components after sintering. As expected,1 and after verification by XRD (Figure 16), the intergranular phase is primarily CuAl2.
Figure 15. Representative microstructure of components in as-sintered state. SEM backscattered image
Figure 14. Component for shock absorbers: green (left) and as-sintered (right)
Figure 16. XRD trace of as-sintered alloy
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
Figure 17. Representative microstructure of components in T4 condition. EDS spot analyses on arrowed particles revealed the presence of iron. SEM backscattered image
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Figure 17 shows the microstructure of the components in the T4 condition. The microstructure consists of an aluminum solid solution and a dispersion of CuAl2 that formed during cooling, or which did not dissolve completely during the solution treatment. Additionally, EDS analyses revealed the presence of a few iron-containing particles which confir ms that the impurity observed in the interdendritic spaces within the original aluminum particles (Figure 3(c)) is iron. Upon sintering, the iron segregates to the liquid phase, forming an intermetallic phase which cannot be dissolved during the solution treatment. This iron-containing phase is present in the assintered compact, but the presence of CuAl2 tends to mask its identification in Figure 15. The presence of this type of particle is unavoidable and limits the final ductility of the alloy. CONCLUSIONS 1. When heating to the sintering temperature, several transient liquids form as a result of reactions between the elemental aluminum, elemental copper, Al-50 w/o Mg, and Al-12 w/o Si particles. 2. Concurrent with the generation and spreading of these transient liquids, alloying elements diffuse to the aluminum particles, leading to the formation of the alloy. 3. Spreading of the transient liquids, and chemical homogenization, result in swelling of the powder compact and the generation of porosity. 4. A permanent liquid (that promotes densification of the alloy by conventional liquid-phase sintering mechanisms) appears in the system at temperatures ≥590°C when alloying is complete. 5. A complex sintering cycle with a slow heating rate after dewaxing (2°C/min), a first holding step for 20 min at 570°C in vacuum, and a second holding step at 590°C for 20 min in nitrogen minimizes distortion and improves density. 6. Samples sintered via this cycle attain a density of 98% of the pore-free density and exhibit attractive mechanical properties in the as-sintered, T4, and T6 conditions. ACKNOWLEDGEMENT The authors gratefully acknowledge the Departamento de Educación, Universidades e Investigación of the Basque Government for financial support of this work. Special thanks are due Polmetasa, Sinterstahl Group, for their collaboration in fabricating the shock absorber components.
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REFERENCES 1. L.F. Mondolfo, Aluminum Alloys: Structure and Properties, 1976, Butterworth & Co. Ltd., London, UK. 2. Aluminum and Aluminum Alloys, ASM Specialty Handbook, edited by J.R. Davis, 1993, ASM International, Materials Park, OH. 3. E.J. Lavernia, J.D. Ayers and T.S. Srivatsan, “Rapid Solidification Processing with Specific Application to Aluminum Alloys”, Int. Mater. Rev., 1992, vol. 37, no. 1, pp. 1–44. 4. A. Greasley and H.Y. Shi, “Microstructural Development during Hot Working of Powdered Aluminum Alloy”, Powder Metall., 1993, vol. 36, no. 4, pp. 288–292. 5. Z. Ishijima, H. Shikata, H. Urata and S. Kawase, “Development of P/M Forged Al-Si Alloy for Connecting Rod”, Advances in Powder Metallurgy and Particulate Materials, compiled by T.M. Cadle and K.S. Narasimhan, Metal Powder Industries Federation, Princeton, NJ, 1996, vol. 4, part 14, pp. 3–14. 6. J.R. Pickens, “Aluminum Powder Metallurgy Technology for High-Strength Applications”, J. Mater. Sci., 1981, vol. 16, pp. 1,437–1,457. 7. M. Hull, “AMC: Leading Edge MMCs and Powder Materials”, Powder Metall., 1997, vol. 40, no. 2, pp. 102–103. 8. M.J. Couper, M. Nauer, R. Baumann and R.F. Singer, ”On the Break-Up and Redistribution of Oxides Following Powder Degassing and Consolidation of Elevated Temperature PM Aluminum Alloys”, Proc. International Conference on PM Aerospace Materials, MPR Publishing Services Ltd., Shrewsbury, England, 1988, paper 28, pp. 1–11. 9. A.D. Jatkar and R.R. Sawtell, “Aluminum PM Alloys for Aerospace Applications”, Proc. of International Conference on PM Aerospace Materials, MPR Publishing Services Ltd., Shrewsbury, England, 1992, paper 15, pp. 1–14. 10. F.V. Beaumont, “Aluminum P/M: Past, Present and Future”, Int. J. Powder Metall., 2000, vol. 36, no. 6, pp. 41–43. 11. P.S. Gilman, “Light High Temperature Aluminum Alloys for Aerospace Applications”, Proc. International Conference on PM Aerospace Materials, ibid. reference no. 9, paper 16, pp. 1–11. 12. “Part Winners Represent New Markets for PM”, Metal Powder Report, 1998, vol. 53, no. 7/8, pp. 12–15. 13. G.B. Schaffer and S.H. Huo, “High Strength Aluminum Alloys”, ibid. reference no. 5, vol. 4, part 14, pp. 27–39. 14. W.J. Ullrich, "Practical Considerations for Fabricating Aluminum P/M Parts", Progress in Powder Metallurgy, Metal Powder Industries Federation, Princeton, NJ, 1986, vol. 42, pp. 535–556. 15. G. Jangg, H. Danninger, K. Schröder, K. Abhari, H.C. Neubing and J. Seyrkammer, “PM Aluminum Camshaft Belt Pulleys for Automotive engines”, Mat.-wiss., u. Werkstofftech, 1996, vol. 27, pp. 179–189. 16. W.J. Huppmann, H. Kirschsieper, W. Häde and G. Schlieper, “Sintered Aluminum Parts for Automotive Applications”, Proc. 7th International Conference on Light Metals, Ver Metallwerke Ranshofen-Berndorf, BraunauRanshofen, Austria, 1981, pp. 236–237. 17. D. Apelian and D. Saha, “Aluminum P/M Processed Components—Challenges and Opportunities”, Proc. Second International Conference on Powder Metallurgy Aluminum and Light Alloys for Automotive Applications, edited by R.A. Chernenkoff and W. F. Jandeska, Jr., Metal
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Powder Industries Federation, Princeton, NJ, pp. 1–10. 18. P. Delarbre and M. Krehl, “Applications of P/M Aluminum Parts—Materials and Processing Schemes”, ibid. reference no. 17, pp. 33–39. 19. R.N. Lumley and G.B. Schaffer, “The Effect of Solubility and Particle Size on Liquid Phase Sintering”, Scripta Materialia, 1996, vol. 35, no. 5, pp. 589–595. 20. R.N. Lumley and G.B. Schaffer, “The Effect of Additive Particle Size on the Mechanical Properties of Sintered Aluminum-Copper Alloys”, Scripta Materialia, 1998, vol. 39, no. 8, pp. 1,089–1,094. 21. T. Wantanabe and K. Yamada, “Effects of Methods of Adding Copper on the Strength of Sintered Aluminum Copper Alloys”, Int. J. Powder Metall., 1968, vol. 4, no. 3, pp. 37–47. 22. H. Danninger, H.C. Neubing and J. Gradl, “Sintering of High Strength Al-Zn-Mg-Cu Alloys to Controlled Dimensions”, Proc. 1998 Powder Metallurgy World Congress and Exhibition, European Powder Metallurgy Association, Shrewsbury, UK, 1998, vol. 5, pp. 272–277. 23. R.N. Lumley, T.B. Sercombe and G.B. Schaffer, “Surface Oxide and the Role of Magnesium during the Sintering of Aluminum”, Metallurgical and Materials Transactions A, 1999, vol. 30A, pp. 457–463. 24. G.B. Schaffer and B.J. Hall, “Sintering of Aluminum in Argon and Nitrogen”, Advances in Powder Metallurgy and Particulate Materials, edited by V. Arnhold, C.L. Chu, W.F. Jandeska, Jr. and H.I. Sanderow, Metal Powder Industries Federation, Princeton, NJ, 2002, part 13, pp. 139–149. 25. I.A. Shibli and D.E. Davies, “Effect of Oxidation on Sintering Characteristics of Al Powder and Effect of some Minor Metallic Additions”, Powder Metall., 1987, vol. 30, no. 2, pp. 97–102. 26. W. Kehl and H. Fischmeister, “Observations on Dimensional Changes during Sintering of Al-Cu Compacts”, Sintering—Theory and Practice, Proc.5th International Round Table Conference on Sintering, edited by D. Kolar, S. Pejovnik and M.M. Ristic, Material Science Monographs, 1982, vol. 14, pp. 269–274. 27. A.P. Savitskii, G.N. Romanov and L.S. Martsunova, “Optimization of the Process from the Standpoint of the New Theory of Liquid Phase Sintering”, Proc.1997 European Conference on Advances in Structural PM Component Production, European Powder Metallurgy Association, Shrewsbury, UK, pp. 150–156. 28. F.F. Nia and B.L. Davies, “Production of Al-Cu and Al-CuSi Alloys by PM Methods”, Powder Metall., 1982, vol. 25, no. 4, pp. 209–215. 29. J.M. Martín, B. Navarcorena, I. Arribas, T. Gómez-Acebo and F. Castro, “Dimensional Changes and Secondary Porosity in Liquid Phase Sintered Al Alloys”, Proc. Powder Metallurgy World Congress and Exhibition (PM2004), edited by H. Danninger and R. Ratzi, EPMA Shrewsbury, UK, 2004, vol. 4, pp. 45–52. 30. H.C. Neubing and G. Jangg, “Sintering of Aluminum Parts: The State-of-the-Art”, Metal Powder Report, 1987, vol. 42, no. 5, pp. 354–358. 31. J.H. Dudas and C.B. Thompson, “Improved Sintering Procedures for Aluminum P/M Parts”, Moder n Developments in Powder Metallurgy, edited by H.H. Hausner, New York, Plenum Press, 1971, vol. 5, pp. 19–36. 32. M. Mühlburger and P. Paschen, “Flüssigphasensintern von AlZnMgCu-Legierungen”, Z. Metallkd., 1993, vol. 84, no. 5, pp. 346–350.
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33. E.M. Daver, W.J. Ullrich and K.B. Patel, “Aluminum P/M Parts—Materials, Production and Properties”, Key Engineering Materials, 1989, vol. 29-31, pp. 401–428. 34. T.B. Sercombe and G.B. Schaffer, “On the Use of Trace Additions of Sn to Enhance Sintered 2xxx Series Al Powder Alloy”, Mater. Sci. Eng. A, 1999, vol. A268, pp. 32–39. 35. H.C. Neubing, J. Gradl and H. Danninger, “Sintering and Microstructure of Al-Si P/M Components”, ibid. reference no. 24, part 13, pp. 128–138. 36. J.M. Martín, T. Gómez-Acebo and F. Castro, “Sintering Behaviour and Mechanical Properties of PM Al-Zn-Mg-Cu Alloy Containing Elemental Mg Additions”, Powder Metall., 2002, vol. 45, no. 2, pp. 173–180. 37. G.B. Schaffer and S.H. Huo, “On Development of Sintered 7xxx Series Aluminum Alloys”, Powder Metall., 1999, vol. 42, no. 3, pp. 219–226. 38. G.B. Schaffer, B.J. Hall, S.J. Bonner, S.H. Huo and T.B. Sercombe, “The Effect of the Atmosphere and the Role of Pore Filling on the Sintering of Aluminum”, Acta Materialia, 2006, vol. 54, no. 1, pp. 131–138. 39. W. Kehl and H.F. Fischmeister, “Liquid Phase Sintering of Al-Cu Compacts”, Powder Metall., 1980, vol. 23, no. 3, pp. 113–119. 40. “MPIF Standard No. 10, Preparing and Evaluating Tensile Specimens of Powder Metallurgy Materials”, Standard Test Methods for Metal Powders and Powder Metallurgy Products, Metal Powder Industries Federation, Princeton, New Jersey, USA, 1998. 41. A.P. Savitskii: Liquid Phase Sintering of the Systems with Interacting Components, 1993, Russian Academy of Sciences, Tomsk. 42. Diffusion in Solid Metals and Alloys, edited by H. Mehrer, Landolt-Börnstein, Numerical Data and Functional Relationships in Science and Technology, New Series, Group III, vol. 26, 1990, Springer-Verlag, Germany. 43. B. Sundman, B. Jansson and J.-O. Andersson, “The Thermo-Calc Databank System”, Calphad, 1985, vol. 9, no. 2, pp. 153–190. 44. “COST 507, Definition of Thermochemical and Thermophysical Properties to Provide a Database for the Development of New Light Alloys”, Proc. Final Workshop, edited by COST Secretariat, European Communities, Brussels, Belgium, 1998, vol. 1. 45. “COST 507, Definition of Thermochemical and Thermophysical Properties to Provide a Database for the Development of New Light Alloys, Thermochemical Database for Light Metal Alloys”, edited by I. Ansara, A.T. Dinsdale and M.H. Rand, European Communities, Brussels, Belgium, 1998, vol. 2. 46. “COST 507, Definition of Ther mochemical and Thermophysical Properties to Provide a Database for the Development of New Light Alloys, Critical Evaluation of Ternary Systems”, edited by G. Effenberg, European Communities, Brussels, Belgium, 1998, vol. 3. 47. J.M. Martín and F. Castro, “Liquid Phase Sintering of P/M Aluminum Alloys: Effect of Processing Conditions”, Journal of Materials Processing Technology, 2003, vol. 143–144, pp. 814–821. 48. R.M. German, Liquid Phase Sintering, 1985, Plenum Press, New York, USA. 49. H.H. Park, S.J. Cho and D.N. Yoon, “Pore Filling Process in Liquid Phase Sintering”, Metall. Trans. A, 1984, vol. 15A, pp. 1,075–1,080. ijpm
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NEW MPIF STANDARD 35, MATERIALS STANDARDS FOR PM STRUCTURAL PARTS 2007 EDITION
The most comprehensively revised Standard in almost 15 years, the new Standard 35, Materials Standards for PM Structural Parts—2007 Edition has just been published. Order enough for your own company use and for free distribution to your existing and potential customers. Keep a supply handy for future trade shows, plant visits, etc. Make sure that your quality assurance/laboratory staff and your sales and marketing personnel/representatives have the latest edition of this standard. Please note that publication of the 2007 Edition of this standard renders the 2003 Edition (and prior editions) obsolete. Previous editions should no longer be distributed but destroyed. The 2007 Edition contains: • Guidelines for specifying a PM Part • New and revised verbiage/data throughout the standard • Alphabetical index listing & guide to materials/designation codes in the family of MPIF Standard 35 publications • New information, revisions and/or re-designation of several material codes, chemical compositions and property data in the standard • 11 new materials, chemical compositions and mechanical property data • New—Steam Oxidation of Ferrous PM Materials • New material sections in the standard This standard is a must-have document for every engineering professional.
Price Item # 1026 Softcover Item # 1026cd CD-ROM Item # 1026e Electronic (pdf)
List $50 $50 $50
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For Quantity Discounts, Please Contact the MPIF Publications Department To Order: FAX:609-987-8523, Phone: 609-945-0009, E-mail:
[email protected] or visit www.mpif.org METAL POWDER INDUSTRIES FEDERATION 105 College Road East, Princeton, NJ 08549-6692
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MEETINGS AND CONFERENCES
2007 5TH INTERNATIONAL CONFERENCE ON MATERIALS PROCESSING FOR PROPERTIES AND PERFORMANCE December 11–15 Singapore www.iommp3.org
2008 AUTOUKRAINE 2008 January 29 Kiev, Ukraine www.wbr.co.uk/autoukraine 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*
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
2008 INTERNATIONAL CONFERENCE ON TUNGSTEN, REFRACTORY & HARDMATERIALS VII June 8–12 Gaylord National Hotel Washington, DC MPIF* BASIC PM SHORT COURSE July 21–23 State College, PA MPIF* PM SINTERING SEMINAR September TBA MPIF* SUPERALLOYS 2008 September 14–18 Champion, PA www.tms.org/Meetings/specialty/ superalloys2008/home.html
2009 POWDERMET2009: MPIF/APMI INTERNATIONAL CONFERENCE ON POWDER METALLURGY & PARTICULATE MATERIALS June 28–July 1 Las Vegas, NV MPIF*
2010 PM2010 WORLD CONGRESS October 10–14 Florence, Italy
INTERNATIONAL CONFERENCE ON ALUMINUM ALLOYS September 22–26 Aachen, Germany www.dgm.de PMP III THIRD INTERNATIONAL CONFERENCE—PROCESSING MATERIALS FOR PROPERTIES December 7–10 Bangkok, Thailand www.tms.org/meetings/ specialty/pmp08
*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
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INSTRUCTIONS FOR AUTHORS International Journal of Powder Metallurgy Instructions for Authors The Journal reports on scientific and technological developments worldwide in the powder metallurgy and particulate materials industries. Articles cover both the scientific/theoretical and practical aspects of the technology. Subjects addressed include: powder production and characterization; compaction; sintering; consolidation to full density; powder injection molding; consolidation to full density; and hybrid particulate processes such as spray forming and thermal spraying. The Journal also embraces review articles, PM industry news, company profiles, a consultants’ corner, newsmakers, conference reports and book reviews. The Journal’s audience includes: powder metallurgists, engineers, researchers, educators, students, technical managers, and users of powders, PM parts and particulate materials. Manuscript Requirements 1. The primary author should be a member of APMI International. 2. a. All manuscripts must be typewritten, double spaced and on one side of the paper only. Authors should limit manuscripts to 10 printed pages in the Journal—including text, references, figures and tables. For guidance, this is roughly 30 double-spaced pages—including text, references, figures and tables. b. Three copies of the manuscript are required. Each should contain original line drawings, photographs and/or micrographs mounted and labeled. Alternatively, digital images will be accepted provided they are in jpg or tif format (at least 4x6 inches at 300 dpi). c. Authors must submit the text portion of their manuscript on disk/CD in Microsoft Word or ASCII format, in addition to the hard copies of the manuscript. Digital images must be in separate files. d. Micrographs must include a magnification marker in the lower right-hand corner. e. Tables and figures must include complete descriptive captions. f. Equations, tables, references and figures should be numbered separately and consecutively throughout the text. g. Papers must be in English, be original and not be published elsewhere. Translated papers published in other languages will be considered provided the author receives permission and submits a copyright release from the publication involved. Particular attention should be given to grammar/syntax; the Journal is not in a position to assist foreign authors in technical writing. 3. Authors and co-authors must provide complete Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
names, mailing addresses, job titles and affiliations, as they wish them to appear in the Journal. A letter accompanying the manuscript should give the name, complete address, telephone number, fax number and e-mail address of the author to whom correspondence should be sent. 4. Each paper must include an abstract of approximately 100 words that summarizes concisely the paper’s objectives, methods, results, observations, mode of analysis and conclusions. 5. Système International (SI) units are mandatory. If industrial practice dictates the use of other systems of units, such units must be included in parentheses. As a guide for authors, frequently used SI units and the corresponding conversion factors are provided overleaf. 6. Weight percent, atomic percent and volume percent should be given as w/o, a/o and v/o, respectively. 7. References must be numbered, placed at the end of the paper, and must adhere to the following format: Journal T. Le, R. Stefaniuk, H. Henein and J-Y. Huôt, “Measurement and Analysis of Melt Flowrate in Gas Atomization”, Int. J. Powder Metall., 1999, vol. 35, no. 1, pp. 51–60. Book R.M. German, Powder Metallurgy Science, Second Edition, 1994, Metal Powder Industries Federation, Princeton, NJ. Article in Book/Conference Proceedings S.H. Luk, F.Y. Chau and V. Kuzmicz, “Higher Green Strength and Improved Density by Conventional Compaction”, Advances in Powder Metallurgy & Particulate Materials, compiled by J.J. Oakes and J.H. Reinshagen, Metal Powder Industries Federation, Princeton, NJ, 1998, vol. 3, part 11, pp. 81–99. Patent I.L. Kamel, A. Lawley and M-H. Kim, “Method of Molding Metal Particles”, U.S. Patent No. 5,328,657, July 12, 1994. Thesis D.J. Schaeffler, “High-Strength Low-Carbon Powder Metallurgy Steels: Alloy Development with Transition Metal Additions”, 1991, Ph.D. Thesis, Drexel University, Philadelphia, PA. Technical Report T.M. Cimino, A.H. Graham and T.F. Murphy, “The Effect of Microstructure and Pore Morphology on Mechanical and Dynamic Properties of Ferrous P/M Materials”, 1998, Hoeganaes Technical
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INSTRUCTIONS FOR AUTHORS
Data, Hoeganaes Corporation, Cinnaminson, NJ. Web Site Content J.R. Dale, “Connecting Rod Evaluation”, Metal Powder Industries Federation, http://www.mpif. org/design/conrod.pdf Private Communication P.W. Taubenblat, 1999, Promet Associates, Highland Park, NJ, private communication. The author(s) will be sent a copyright form, which must be returned before the paper can be published. A reprint order form will also be sent to the author(s). All manuscripts submitted to the Journal should be sent to the Editor-in-Chief, who will make an initial
decision on the paper’s suitability for external review. Papers are then subject to review by two members of the Editorial Review Committee. Papers are accepted with the understanding that they may be returned to the author(s) for revision, based on the reviewer’s recommendations. They may also be edited by the Journal’s staff for clarity and conciseness. Articles should be submitted to: Dr. Alan Lawley Editor-in-Chief International Journal of Powder Metallurgy 105 College Road East Princeton, NJ 08540-6692 USA
SYSTÈME INTERNATIONAL UNITS (SI) AND CONVERSION FACTORS Source: R.M. German, Powder Metallurgy Science, Second Edition, Metal Powder Industries Federation, Princeton, NJ 1994 Length Conversions: 1 m = 39.4 in. (inch) 1 m = 3.28 ft. (foot) 1 m = 1.09 yd. (yard) 1 cm = 0.394 in. (inch) 1 mm = 0.0394 in. (inch) 1 µm = 39.4 µin (microinch) 1 nm = 10 Å (angstrom) Area and Volume Conversions: 1 cm2 = 0.155 in.2 (square inch) 1 m2 = 1,550 in.2 (square inch) 1 cm3 = 0.061 in.3 (cubic inch) 1 m3 = 35 ft.3 (cubic foot) 1 L = 1,000 cm3 (cubic centimeter) 1 L = 0.264 gal. (gallons) 1 L = 1.06 qt. (quart) Amount of Substance Conversion: 1 mol = 6.022·1023 molecules Density Conversions: 1 Mg/m3 = 1 g/cm3 1 g/cm3 = 0.0361 lb./in.3 (pound per cubic inch) 1 kg/m3 = 10-3 g/cm3 Temperature Conversion: to convert K to °F (fahrenheit), multiply by 1.8 then subtract 459.4°F to convert °C to °F (fahrenheit), multiply by 1.8 then add 32°F Heating and Cooling Rate Conversions: 1 K/s = 1°C/s = 1.8°F/s 1 K/min = 1.8°F/min Mass Conversions: 1 g = 0.035 oz. (ounce) 1 kg = 2.2 lb. (pound) 1 Mg = 1.1 ton (ton = 2,000 pounds) Force Conversions: 1 N = 105 dyne 1 N = 0.225 lb. force (pound force) Pressure, Stress and Strength Conversions: 1 Pa = 0.0075 torr (millimeter of mercury)
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1 Pa = 10 dyne/cm2 (dyne per centimeter square) 1 kPa = 0.145 psi (pounds per square inch) 1 MPa = 9.87 bar (atmosphere) 1 MPa = 145 psi (pounds per square inch) 1 MPa = 0.145 kpsi (thousand pounds per square inch) 1 Gpa = 145 kpsi (thousand pounds per square inch) Energy Conversions: 1 J = 9.48 ·10-4 btu (British thermal unit) 1 J = 0.737 ft.·lb. (foot pound) 1 J = 0.239 cal (calorie) 1 J = 107 erg 1 J = 2.8 ·10-7 kw ·h (kilowatt hour) 1 J = 6.24 ·1018 eV (electron volt) 1 J = 4.83 hp · h (horsepower · hour) 1 J = 1 W· s (watt second) 1 J = 1 V· C (volt coulomb) 1 kJ = 0.239 kcal (kilocalorie) Power Conversions: 1 W = 0.737 ft.· lb./s (foot pound per second) 1 W = 1.34 ·10-3 hp (horsepower) Thermal Conversions: 1 J/(kg · K) = 2.39 ·10-4 btu/(lb .·°F) (British thermal unit per pound per degree fahrenheit) 1 J/(kg · K) = 2.39 ·10-4 cal/(g ·°C) (calorie per gram per degree celsius) 1 W/(m · K) = 0.578 btu/(ft.· h · °F) (British thermal unit per foot per hour per degree fahrenheit) 1 W/(m · K) = 2.39 · 10-3 cal/(cm · s · °C) (calorie per centimeter per second per degree celsius) Viscosity Conversions: 1 Pa· s = 1 kg/(m · s) 1 Pa· s = 10 P (poise) 1 Pa· s = 103 cP (centipoise) Stress Intensity Conversion: 1 MPa · m1/2 = 0.91 kpsi · in.1/2 (kilopounds per square inch times square root inch) Magnetic Conversions: 1 T = 104 G (gauss) 1 A/m = 1.257· 10-2 Oe (oersted) 1 Wb = 108 Maxwell Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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YEARLY CONTENTS INTERNATIONAL JOURNAL OF POWDER METALLURGY TABLE OF CONTENTS FOR VOLUME 43, NUMBERS 1–6, 2007 43/1 JANUARY/ FEBRUARY 2007 3 5 7 9 13 15
Editor’s Note Newsmaker John F. Sweet, PMT PM Industry News in Review Company Profile Hawk MIM PMT Spotlight On …Denis Christopherson Consultants’ Corner James G. Marsden, FAPMI
OUTSTANDING TECHNICAL PAPER FROM POWDERMET2006 17 Dimensional Control In Copper/Nickel-Containing Ferrous Powder Metallurgy Alloys B. Lindsley and T. Murphy ARCHAEOTECHNOLOGY 27 About the Pre-Hispanic Au-Pt “Sintering” Technique for Making Alloys M. Noguez, R. Garcia, G. Salas, T. Robert and J. Ramirez RESEARCH & DEVELOPMENT 35 Production of Nanometric Tungsten Carbide Powders by Planetary Milling B.G. Butler, J. Lu, Z.Z. Fang and R.K. Rajamani 45 48 49 64
DEPARTMENTS Conference Report Meetings and Conferences Web Site Directory Advertisers’ Index
43/2 MARCH/APRIL 2007 3 4 7 11 13
FOCUS: HARDMETALS 17 Hardmetals: Past, Present, and Future A. Bose 21 Magnetic Saturation and Coercivity Measurements on Chromium-Doped Cemented Carbides G.K. Schwenke and J.V. Sturdevant 33 Recent Advances in Tungsten-Based Hardmetals P.K. Mehrotra, K.P. Mizgalski and A.T. Santhanam 41 Early-Stage Sintering Densification and Grain Growth of Nanosized WC-Co Powders P. Maheshwari, Z. Fang and H.Y. Sohn 49 Microwave Sintering of Submicron Cemented Carbides L. Chen, T. Dennis, P. Gigl and B. Hampshire 60 61 63 64
ENGINEERING & TECHNOLOGY 41 Evaluation of Global PM Oil-Impregnated Bearings H.I. Sanderow, FAPMI and L.F. Pease III, FAPMI, PMTII 49 Chip Reclamation in Green Machining for HighPerformance PM Components E. Robert-Perron, C. Blais, S. Pelletier, Y. Thomas and S. St-Laurent RESEARCH & DEVELOPMENT 57 Kinetics of Cobalt Gradient Formation During Liquid-Phase Sintering of Functionally Graded WC-Co O. Eso, Z.Z. Fang and A. Griffo 65 66 69 71 72
DEPARTMENTS Meetings and Conferences APMI Membership Application Instructions for Authors PM Bookshelf Advertisers’ Index
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
DEPARTMENTS Meetings and Conferences Instructions for Authors PM Bookshelf Advertisers’ Index
43/4 JULY/AUGUST 2007
43/3 MAY/JUNE 2007 3 Editor's Note 7 PM Industry News in Review 9 Growth Opportunities for PM in India Peter K. Johnson 15 PMT Spotlight On … Timothy J. Hokkanen 17 Consultants’ Corner Howard I. Sanderow, FAPMI 21 New Technology Drives PM’s Future Peter K. Johnson 29 Exhibitor Showcase: PowderMet2007
Editor’s Note PM Industry News in Review Company Profile Korea Sintered Metals PMT Spotlight On …Charles B. Wood Consultants’ Corner Brian H. Pittenger
3 5 9 11 15
Editor's Note PM Industry News in Review PMT Spotlight On … Patricia A. Ditson Consultants’ Corner Myron I. Jaffe APMI Fellow Awards Thomas F. Murphy and Howard I. Sanderow 17 2007 PM Design Excellence Awards Winners P.K. Johnson HEALTH & ENVIRONMENT 27 The New European REACH Regulation: A Major Challenge to Manufacturers and Importers P. Brewin ENGINEERING & TECHNOLOGY 33 State of the PM Industry in North America—2007 E. Daver and C.J. Trombino RESEARCH & DEVELOPMENT 39 High-Performance PM Steels Utilizing Extra-Fine Nickel L. Azzi, T. Stephenson, S. Pelletier and S. St-Laurent 51 Precipitation Hardening PM Stainless Steels C. Schade, P. Stears, A. Lawley and R.D. Doherty 60 61 63 64
DEPARTMENTS Meetings and Conferences APMI Membership Application PM Bookshelf Advertisers’ Index
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YEARLY CONTENTS 43/5 SEPTEMBER/OCTOBER 2007 2 3 7 9 11 17
23 31 43 55
Editor's Note Newsmaker Chaman Lall PM Industry News in Review PMT Spotlight On … Ken Watson Consultants’ Corner Olle Grinder PM Metallography Competition Grand Prize FOCUS: COPPER PM—NEW DEVELOPMENT & APPLICATIONS Expanding the Market for PM Copper: Beyond Self-Lubricating Bearings P. Taubenblat Electronic Applications for Copper Powder J.A. Shields, Jr. and I. Smid Copper-Base PM—Past, Present & Future W. Ullrich Metal Powder Injection Molding of Copper and Copper Alloys for Microelectronic Heat Dissipation R.M. German and J.L. Johnson
64 Advertisers’ Index
43/6 NOVEMBER/DECEMBER 2007 2 5 7 9 11
Editor's Note Newsmaker Alexander Litvintsev PM Industry News in Review PMT Spotlight On … Maryann Wright PM Metallography Competition Research & Development, Product/Process Control and Artistic Categories 25 Outstanding Poster Awards Y.I. Seo, D.H. Shin, K.H. Min, Y.D. Yoon, S-Y Chang, K.H. Lee, and Y.D. Kim; C. McClimon, J.J. Williams and N. Chawla 27 Consultants’ Corner J.T. Strauss 35 Axel Madsen/CPMT Scholar Reports P. Lapointe, C. McClimon, D. Sampson and M. Sexton ENGINEERING & TECHNOLOGY 39 Lubricants for High-Density Compaction at Moderate Temperatures L. Azzi, Y. Thomas and S. St-Laurent RESEARCH & DEVELOPMENT 47 R&D in Support of Powder Injection Molding: Status and Projections R.M. German 59 Sintering Response & Microstructural Evolution of an Al-Cu-Mg-Si Premix J.M. Martin and F. Castro 71 72 75 77 79 80
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DEPARTMENTS Meetings and Conferences APMI Membership Application Instructions for Authors Table of Contents: Volume 43, Numbers 1–6, 2007 PM Bookshelf Advertisers’ Index
Volume 43, Issue 6, 2007 International Journal of Powder Metallurgy
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ADVERTISERS’ INDEX
ADVERTISER
FAX
WEB SITE
PAGE
ABBOTT FURNACE COMPANY __________________(814) 781-7334_______www.abbottfurnace.com______________________58 ACUPOWDER INTERNATIONAL, LLC _____________(908) 851-4597_______www.acupowder.com ________________________34 ASBURY CARBONS ___________________________(908) 537-2908_______www.asbury.com ___________________________10 ELNIK SYSTEMS _____________________________(973) 239-6066_______www.elnik.com _____________________________20 HOEGANAES CORPORATION ___________________(856) 786-2574_______www.hoeganaes.com ________INSIDE FRONT COVER KITTYHAWK PRODUCTS _______________________(714) 895-5024_______www.kittyhawkinc.com_______________________22 NORILSK NICKEL ____________________________(+ 7 495) 785 58 08 ___www.norilsknickel.com _______________________4 NORTH AMERICAN HÖGANÄS INC. ______________(814) 479-2003_______www.nah.com _______________________________3 PRINCETON ONE_____________________________(440) 243-4868_______www.princetonone.com ______________________31 QMP ______________________________________(734) 953-0082_______www.qmp-powders.com _____________BACK COVER SCM METAL PRODUCTS, INC. __________________(919) 544-7996_______www.scmmetals.com _________INSIDE BACK COVER
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
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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 43, Issue 6, 2007 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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