SiC-TiC and SiC-TiB2 composites densified by liquid-phase sintering

Particle-reinforced SiC composites with the addition of TiC or TiB2 were fabricated at 1850 degrees C by hot-pressing. Densification was accomplished by utilizing a liquid phase formed with added Al2O3, Y2O3, and surface SiO2 on SiC. Their mechanical and electrical properties were measured as a function of TiC or TiB2 content. Adding TiC or TiB2 to the SIC matrix increased the toughness, and decreased the strength and electrical resistivity. The fracture toughnesses of SiC-50 wt % TiC and SiC-50 wt % TiB2 composites were approximately 60% and 50%, respectively, higher than that of monolithic SiC ceramics. Microstructural analysis showed that the toughening was due to crack deflection, with some possible contribution from microcracking in the vicinity of TiC or TiB2 particles.