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M. Brieseck, I. Hünsche, B. Caspers, B. Szesny, W. Lengauer:
"Optimised Sintering and Grain-Growth Inhibition of Ultrafine and Near-Nano Hardmetals";
Talk: "Euro PM2009" International Powder Metallurgy Congress & Exhibition, Copenhagen; 10-12-2009 - 10-14-2009; in: "Euro PM2009", European Powder Metallurgy Association, Shrewsbury UK (2009).

The sintering behaviour of two different grades (one ultrafine grade and one nanosized development product) of WC powders was investigated mainly for WC-8 wt.% Co hardmetals. By optimising the sintering profile, based on outgassing reactions and shrinkage behaviour, almost full density could be reached within relatively short sintering time. Interrupted sintering, including rapid cooling from the sintering temperatures and inspection by FE-SEM microscopy was employed to characterise the densification behaviour. In addition, an examination of the WC grain size as a function of the sintering temperature and of the type of grain-growth inhibitors was performed. By use of various grain-growth-inhibiting carbides and nitrides (VC, Cr₃C₂, TaC, Cr₂N and combinations) the grain growth could be reduced to a large extent in sintering. As a result the nanoscaled hardmetals (with grain sizes in the range of 100 nm) obtained with the nanosized WC powder exhibit a high potential for increasing hardness without significant loss in fracture toughness compared to ultrafine hardmetal grades with identical binder content.

WC-Co, hardmetal, sintering, grain-growth inhibition, ultrafine, nano, mechanical properties