Suppression of abnormal grain growth in WC–Co via pre-sintering treatment

When 92WC–8Co (wt%) samples with WC powder of 0.4 μm size were sintered by conventional liquid phase sintering at 1400 °C, densification to more than 99% of the relative density was obtained after only 1 h of sintering and abnormal grain growth occurred. However, when similar samples were pre-sintered in a solid state before liquid phase sintering, the samples were densified to more than 99% of the relative density without the formation of any abnormal grains within 30 min of liquid phase sintering. As the grain growth behavior during liquid phase sintering was similar for the two kinds of samples, these findings show that pre-sintering in the solid state is an effective means of avoiding abnormal grain growth in submicron-sized WC–Co cemented carbides. As a result of the suppression of abnormal grain growth with full densification, the Vickers hardness of the samples pre-sintered and sintered for 30 min was higher than that of conventionally sintered samples.