Transformation of polysilicon cutting waste into SiC/α-Si3N4 composite powders via electromagnetic induction heating

Abstract In order to use polysilicon cutting waste more efficiently, SiC/α-Si3N4 composite powders were prepared via electromagnetic induction heating at ambient pressure. Factors affecting synthesis and reaction mechanisms of the SiC/α-Si3N4 composite powders were investigated. Results show that the morphology of obtained α-Si3N4 consists of particles equiaxed with diameter in the micron range and one-dimensional Si3N4 nanowires with diameter of tens to hundreds of nanometers and length of up to tens of microns. It was found that the addition of NH4Cl can promote nitridation by controlling reaction temperature and participating in the reaction. In addition, the existence of Fe2O3 impurities was found to be beneficial to the formation of α-Si3N4 in reaction process by removing the SiO2 film from silicon and providing FeSi2 liquid phase as effective pass for vapor phase. Mechanisms used to grow Si3N4-NWs were vapor-solid (VS) and vapor-liquid-solid (VLS) depositions.