composites of varying content from 0 to 52 vol.% were prepared by pressureless sintering. When these composites were sintered at the mechanical properties such as elastic modulus, strength and toughness increased with increasing content. On the other hand, at a sintering temperature of , the mechanical properties reduced gradually with increasing content. The main reason was deduced from the onset of spontaneous microcracking and the critical particle size for microcracking was calculated approximately 5.6 .

The effect of SiC addition on sintering behaviors and microstructures of TiB2 ceramics were studied. The sintering of TiB2 was limited due to the surface diffusion and rapid grain growth at high temperature. However the addition of SiC to TiB2 ceramics improved the densification to above 99% of the theoretical density. The sintering of TiB2-SiC composite starts at 120 with the melting of the oxides in particle surface as impurities. After the reduction of the oxide by additional cabon at above 140, the grain boundary diffusion through the interface of TiB2-SiC play an important role. TEM observation showed neither chemical reactions nor other phases formed at the TiB2-SiC interfaces but the microcracks were observed due to the mismatch of thermal expansion between TiB2-SiC.