Microstructure and electrical properties of Si3N4–TiN composites sintered by hot pressing and spark plasma sintering

Electroconductive Si3N4–TiN composites were fabricated from micron-sized Si3N4 and nano-sized TiN powders by powder processing routes. The specimens were consolidated by hot pressing (HP) and spark plasma sintering (SPS). High densities (>98%) were obtained by sintering at temperatures ≥1500 °C using both sintering methods. The TiN phase grows rapidly during the liquid phase sintering, and its grain size increases with sintering temperature, leading to the increase in electrical resistivity. Dense materials produced by SPS possess significantly higher resistivity than the hot-pressed materials due to the larger TiN grain size and the presence of crystallized grain boundary phase.