Effect of TiC Content on Microstructure and Properties of Pressureless SinteredTiC-Al₂O₃ Conductive Ceramic Composites

Taking Al₂O₃ and TiC powders as raw materials, TiC-Al₂O₃ conductive ceramic composites were prepared by pressureless sintering technique. The effects of TiC content on the microstructure and properties of ceramic composites were investigated. The results show that TiC-Al₂O₃ conductive ceramic composites mainly consisted of Al₂O₃ phase and TiC phase. With increasing content of TiC, the relative density decreased, and the open porosity increased; when the TiC volume fraction was 30%, the ceramic composites had the maximum relative density of 95.5% and the minimum open porosity of 3.0%. The conductive phase TiC in ceramic composites was connected as a network structure; with increasing TiC content, the network structure formed by TiC became more complete,the hardness of ceramic composites increased first and then decreased, the resistivity and fracture toughness decreased, and the bending strength increased. When the TiC volume fraction was 45%, the bending strength was the highest and the conductivity was the lowest, which were 361 MPa, 6.95×10^-6 Ω·m, respectively.