TiN coated SiC composite powders produced by controlled hydrolysis

TiN coated SiC powders were prepared by the method of controlled hydrolysis and subsequent nitridation with NH3 gas. The effects of the type of TiO₂ precursor, the way of precipitation, the amount of water on particle size and the dispersibility of hydrolysis product of TiO₂ were investigated. The structural evolution of the TiO₂ coated layer under varied nitridation temperature was analyzed. The main focus was put on the mechanisms of controlled hydrolysis and subsequent nitridation and the characterization of the morphology, phase constitution and thermal stability of the obtained TiN coated SiC powders. The results indicate that hydrolysis of the uniform coating of TiO₂ layer can be easily achieved by controlled hydrolysis than the precipitation method. The amount of the added water is the key factor to reduce the aggregation of TiO₂. TiO₂ film can be transformed completely to TiN after nitridation at the temperature of 1000°C. The obtained TiN film is uniform and continuous. The sizes of TiN particles covering SiC powder are 30-70 nm. When the temperature is higher than 546°C, TiN film is easily oxidized in air and lost its stability.