Microstructure and mechanical properties of WC-SiC composites

Abstract

Tungsten carbide-silicon carbide (WC-SiC) composites were pressure-sintered with a resistance-heated hot-pressing machine at a sintering temperature of 1600°C. The dense sintered bodies were obtained by the SiC addition ranging from 2-10 mol%. Below 4.85 mol% SiC, WC grains grew abnormally, exhibiting high aspect ratios and intersecting one another. There were no preferential orientations for the abnormal WC grains, which had an irregular plate-like morphology with a thickness of about 3 mm and lengths ranging from 50-100 mm. The Vickers hardness decreased with increasing SiC up to 4.85 mol% and increased above this concentration. The Vickers hardness in the range of 2-4.85 mol% SiC was much lower than that of pure WC, 25.3 GPa, and had a constant value of 20.5 GPa above 7.5 mol% SiC. The fracture toughness increased with the addition of SiC, but large amounts of SiC decreased the fracture toughness. The fracture toughness of the WC-SiC composites was higher than that of the pure WC. © 2011 The Japan Institute of Metals.