Synthesis of Si3N4–TiN–SiC composites by combustion reaction under high nitrogen pressures

Si3N4–TiN–SiC composites were synthesized from TiSi2 and SiC mixtures via the combustion reaction under high nitrogen pressure. The nitridation mechanism of TiSi2 was analyzed. The results show that the nitridation of TiSi2 produced TiN and Si firstly, and Si3N4 phase was formed by the further nitriding of Si. The molten eutectic phase and its agglomeration between Si and TiSi2 formed one core-shell structure and affected the nitridation process. Under higher nitrogen pressure, the nitridation reaction was complete and the relatively dense Si3N4–TiN–SiC composites obtained. TEM observation revealed inhomogeneous Si3N4 grain size, amorphous phase, cavities, microcracks and dislocations, and graphite from the nitridation of SiC in the microstructure.