Synthesis of Si 3N 4–TiN–SiC composites by combustion reaction under high nitrogen pressures

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Abstract Si 3 N 4 –TiN–SiC composites were synthesized from TiSi 2 and SiC mixtures via the combustion reaction under high nitrogen pressure. The nitridation mechanism of TiSi 2 was analyzed. The results show that the nitridation of TiSi 2 produced TiN and Si firstly, and Si 3 N 4 phase was formed by the further nitriding of Si. The molten eutectic phase and its agglomeration between Si and TiSi 2 formed one core-shell structure and affected the nitridation process. Under higher nitrogen pressure, the nitridation reaction was complete and the relatively dense Si 3 N 4 –TiN–SiC composites obtained. TEM observation revealed inhomogeneous Si 3 N 4 grain size, amorphous phase, cavities, microcracks and dislocations, and graphite from the nitridation of SiC in the microstructure.