Development and characterization of electroconductive Si₃N₄-TiN composites

Dense Si₃N₄-TiN composites, with the second phase ranging from 20 to 40 vol.%, were produced by hot pressing, gas-pressure sintering and pressureless sintering under nitrogen gas atmosphere. The influence of densification technique and parameters and of amount and grain size of TiN particles on microstructure, mechanical properties, electrical resistivity and oxidation resistance was evaluated. The addition of TiN particles increases the stiffness and the fracture toughness of the base material. For TiN content higher than 30 vol.% the electrical resistivity of the composites is less than 10^-3 ωcm. An evident effect of the grain size distribution of TiN powders on some mechanical properties was ascertained. The thermal stability of the composites is strongly affected by the amount of the second phase.