Microstructural design of sliding-wear-resistant liquid-phase-sintered SiC: An overview

We have reviewed the effect of microstructure – content of intergranular phase, grain size, and grain shape – on the lubricated, sliding-wear of pressureless liquid-phase-sintered (LPS) SiC ceramics. The sliding-wear resistance in LPS SiC decreases with an increase in the content of the intergranular phase or an increase in the equiaxed-grain coarsening. However, the sliding-wear resistance is dramatically improved with anisotropic-grain coarsening. Based on these results we suggest two strategies for the microstructural design of low-cost, sliding-wear resistant SiC-based ceramics: (1) grain refinement, and (2) grain elongation. The latter strategy allows the materials to be simultaneously in situ toughened, and we describe its optimization by judicious selection of the SiC starting powder.