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November 24, 1999

3 Min Read
Materials for IMMC:  MIM powders and feedstocks

Nickel. Electronic and automotive components are being metal injection molded with a new nickel powder from Novamet. According to the company, the high purity level and smooth spherical shape of Type 4SP improve processing and product quality. It can be used in alloy compositions such as simple 2 and 8 percent nickel steels, and also in 50/50 nickel-iron alloys, which have a low coefficient of thermal expansion—a critical property in high-temperature applications.

Novamet offers four sizes of Type 4SP: <37 µm, <20 µm, <20 to >10 µm , and <10 µm. However, the finest grade has proved to be the preferred choice for MIM. Its shape and particle size mirror that of the carbonyl iron powder used in MIM, and therefore allow for its uniform distribution throughout alloy composition. Typical properties include 99.8 percent nickel, 500 ppm of oxygen, 500 ppm of carbon, less than 100 ppm of iron, and 2 ppm of sulfur.

Novamet Specialty Products Corp.
Wyckoff, NJ
Phone: (201) 891-7976
Fax: (201) 891-9467
Web: www.novametcorp.com

Molybdenum. Although it was developed more than 10 years ago and has few current applications, CSM Industries’ MIMP molybdenum powder shouldn’t be counted out from the pool of MIM materials. Originally developed for use by the military in missiles, MIMP has also proved to be a useful element for blending with stainless steel or other metal powders when additional strength and hardness are required.

Engineers at CSM encountered flow problems with traditional molybdenum because of its angular shape and agglomerated nature. The spongelike particles would soak up high concentrations of the binder, resulting in a poor loading ratio. To solve this problem, the molybdenum was deagglomerated (without atomization), changing its angular, crystalline composition to that resembling a smooth, semispherical stone. Flow improved, and loadings of 60 vol-% are now the norm.

MIMP has been used in heat-sink applications, microwave housings, and missile thrust vector control veins. Average agglomerate size ranges from 2.5 to 8 µm. Company sources report pricing at around $25 to $30/lb.

CSM Industries, Coldwater, MI
Phone: (517) 278-8325
Fax: (517) 278-7814

Tungsten carbide. MIM fabricator and feedstock formulator Osprey Metals now offers tungsten carbide powders in addition to its existing line of alloy powders for MIM applications. The company touts the spherical particle morphology as a plus when formulating into feedstock, enhancing rheological properties. Particle sizes are <22 µm.

The grade currently available contains 88 percent tungsten carbide and 12 percent cobalt; the company reports that two more grades will follow, with compositions of 94/6 and 83/17. Custom feedstocks will also be available in the future, Osprey reports.

Other products in the company’s portfolio of 100 alloy compositions include those in the microfine range. Among these are stainless steel-, cobalt-, copper-, and nickel-based alloys that can be blended with carbonyl iron. All alloys are atomized with nitrogen or argon as opposed to water, resulting in lower oxygen content and higher tap densities. Particle sizes start as low as 90 wt-%, <5 µm.

Osprey Metals Ltd.
Neath, U.K.
Phone: +44 (1639) 634121
Fax: +44 (1639) 630100
Web: www.ospreymetals.co.uk

Use this link to see separate article on nickle-free stainless steel.

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