The effects of B4C addition on the microstructure and mechanical properties of SiC prepared using powders recovered from kerf loss sludge

Abstract In this study, high purity SiC powders (~ 99.3%), which were recycled from the kerf loss sludge using hydro-cyclone, classifier and direct carbonization and which have purity similar to the commercial SiC powders used to fabricate structural components, were used to investigate the effect of B 4 C addition on the microstructure and mechanical properties of the sintered SiC. B 4 C phase and graphite were observed on the grain boundaries between SiC grains, and the amount of B 4 C phase at the grain boundaries was increased with increasing B 4 C contents. Both the phases on the grain boundaries impeded the growth of SiC grains and led to the high porosity, which resulted in the decrease in density and hardness. The addition of B 4 C was found to have negative effect on the density and hardness of SiC. The fracture toughness, however, was enhanced with the increase in the B 4 C content. The impediment of crack propagation by the B 4 C phase was found to be related to the improvement of fracture toughness as the amount of B 4 C content was increased