Electrical percolation and mechanical properties of Si ₃ N ₄ –TiC _0.5 N _0.5 composite ceramics

Abstract In recent years, the application of Si 3 N 4 ceramics has been developing in the direction of structural and functional integration. In this work, highly densified Si 3 N 4 –TiC 0.5 N 0.5 composites were fabricated by hot pressing with Y 2 O 3 –MgO sintering additives, and the effects of TiC 0.5 N 0.5 content on phase composition, microstructure, mechanical properties, and electrical properties were studied. When the content was higher than 20 vol%, the TiC 0.5 N 0.5 conductive network was constructed. The resistivity decreased with the increase of TiC 0.5 N 0.5 content, and the percolation threshold was 20 vol%, where the resistivity dropped sharply by six orders of magnitude. The addition of TiC 0.5 N 0.5 with PTC characteristic neutralized the temperature sensitivity of the resistivity of Si 3 N 4 ceramic with NTC characteristic. Si 3 N 4 –30vol%TiC 0.5 N 0.5 composites showed good electrical conductivity, as well as good temperature resistance stability characteristic at RT–400°C with a resistivity of 15.5 ± 2.4 Ω cm. The Si 3 N 4 –TiC 0.5 N 0.5 composites showed relatively high mechanical properties, the flexural strength, elastic modulus, fracture toughness, and hardness of Si 3 N 4 –30vol%TiC 0.5 N 0.5 composites were 750 MPa, 340 GPa, 6.94 MPa m 1/2 , and 14.8 GPa, respectively. The Si 3 N 4 ‐based ceramics with integrated structural and functional properties have been obtained in this work, which is expected to be applied to sophisticated electrical devices such as electrostatic chuck, wafer heater, and infrared light source.