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Uneven shrinkage causes problems for cheaper hardmetal tooling

 
: Simchi, A.; Petzoldt, F.; Hartwig, T.; Veltl, G.

:

Metal Powder Report 66 (2011), Nr.5, S.29-32
ISSN: 0026-0657
Englisch
Zeitschriftenaufsatz
Fraunhofer IFAM ()

Abstract
Researchers in Germany and Iran have looked at methods of manufacturing wear parts using nanostructured hardmetal combined with a cheaper stainless steel component in pursuit of cost effectiveness. Nanostructured WC-10%Co-0.9%VC and 316L SS powders were used as starting materials. A polymer-wax binder composed of polyethylene copolymer-ethylene vinyl acetate, carnauba wax, paraffin and stearic acid was used to prepare the hardmetal feedstock in a laboratory kneader with z-mixing blades at a temperature of 120°C. The assembled PIM parts were sintered in a laboratory sintering furnace under nitrogen according to different sintering cycles in the temperature range of 1320-1360°C with a heating rate of 10-20 K/min. The density of the sintered samples was measured by the water displacement method. The team found that reactions occur between the hardmetal and stainless steel at high temperatures, which eventually distort the shape of PIM parts due to excess melt formation eve n at temperatures as low as 1250°C.

: http://publica.fraunhofer.de/dokumente/N-209005.html