Abstract
Propagation of a combustion wave during self-propagating high-temperature synthesis of TiC with gas formation was observed in-situ with a high-speed CCD camera. According to this experiment, combustion wave behavior and its relationship with the developed microstructures of products was evaluated. Combustion wave did not propagate uniformly in any of the cases at a microscopic level. Lack of uniformity increased with increasing the size of raw Ti powders and the amount of TiC as a diluent additive, but decreased with the amount of SiC. Heat-treated carbon black results in further degradation of uniformity in wave propagation for the Ti-C, Ti-C-TiC, and Ti-C-SiC systems. Layered structures of the products were strongly affected by such a lack of uniformity. However, the particle diameter of Ti did not strongly affect combustion wave propagation in the Ti-C-Si system, thus, no significant formation of layered structure occured in the products as compared with the Ti-C, Ti-C-TiC or Ti-C-SiC systems. TiC additive decreased the thickness of the reaction zone, while SiC addition increased it. Heterogeneity formation of melt (s) during the synthesis resulted in a more layered structure and brittle products.
