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

Si3N4-TiN-SiC composites were prepared from TiSi2 and SiC by combustion synthesis under a nitrogen pressure of 130 MPa. The nitridation of TiSi2 initially produced TiN and Si, with Si3N4 forming by nitridation of Si. The molten eutectic phase and its agglomeration between Si and TiSi2 formed a core-shell structure which affected the nitridation process. The nitridation reaction was complete under high nitrogen pressure, giving relatively dense composites. TEM studies showed an inhomogeneous Si3N4 grain size, an amorphous phase, cavities, microcracks and dislocations, and graphite from the nitridation of SiC. 11 refs.