Combustion synthesis of α-Si3N4 powders using in-situ nano-SiO2 coated Si and Si3N4 reactants

Alpha phase silicon nitride (alpha-Si3N4) powders were synthesized by combustion reaction of the in-situ nano-SiO2 coated Si and Si3N4 reactants with pressurized nitrogen. The combustion temperature profile as well as the product phase composition and morphology were investigated. Regardless of the combustion temperature reached as high as 1800 degrees C, up to 86 wt% alpha-Si3N4 was obtained in the combustion-synthesized product from the reactants with only 6 wt% SiO2 addition, which is three times higher than that of without SiO2 coating, meanwhile, the morphology of Si3N4 grains changed from rod-like to equiaxed grain , indicating the in-situ coated SiO2 tailored the nitridation reaction path of Si successfully by enhancing the silicon monoxide (SiO) gas phase formation.

Automated summary

By in-situ coating SiO2, the formation of silicon monoxide (SiO) gas phase was enhanced, successfully regulating the nitridation reaction path of silicon, resulting in increased yield and purity of alpha-Si3N4.