In-situ synthesis of Si₃N₄TiN nanocomposite powders in cryogenic solution

A new method of Si₃N₄/TiN nanocomposite powders through reaction at low temperatures was proposed and tested. The reduction of titanium chloride and silicon chloride by sodium was conducted in liquid ammonia at the temperature range of -40°C- 50°C, and titanium nitride and silicon nitride nanopowders were obtained. Based on these reactions, in-situ coating and co-precipitation were conducted. The TiN nano-particles deposited on the surface of Si₃N₄ particles as the nuclei in the in-situ coating and in the co-precipitation two or more source of ions were reduced uniformly in the liquid ammonia. Si₃N₄TiN nanocomposite powders were prepared by both the routes and were characterized with X-ray diffraction, transmission electron microscopy. The effects of in-situ treatment and the particle size on the morphology of the composite were discussed.