Effect of Sintering Additive Al₂O₃-Y₂O₃ Addition on Structure and Properties ofTiC Ceramics by Pressureless Liquid Phase Sintering

TiC ceramics were prepared by pressureless liquid phase sintering at 1 850 ℃. The effect of the mass fraction (0,6%, 8%,10%) of sintering additive Al₂O₃-Y₂O₃ (Al₂O₃ to Y₂O₃ molar ratio of 1.5) on the microstructure and properties of TiC ceramics was investigated. The results show that TiC phase, YAM (Y₄Al₂O₉) phase and YAG (Y₃Al₅O₁₂) phase existed in TiC ceramics after adding sintering additive. With increasing mass fraction of sintering additive from 0 to 10%, the relative density of ceramics increased from 94.50% to 97.86%, the open porosity decreased from 0.77% to 0.21%, the YAM and YAG phases increased and gradually aggregated, and the fracture toughness, Vickers hardness and flexural strength all increased first and then decreased. When the mass fraction of sintering additive was 6%, the fracture toughness and Vickers hardness reached the maximum value of 6.2 MPa·m^1/2 and 19 GPa, respectively. When the mass fraction of sintering additive was 8%, the flexural strength reached the maximum value of 524 MPa. The resistivity of ceramics was between 1.00×10^-6-2.00×10^-6 Ω·m, and the addition of sintering additives affected the electrical conductivity little.