Effect of the diluent on combustion synthesis of silicon nitride

SiN powders were prepared by combustion synthesis with 1- and 3-μm α-SiN, β-SiN diluent and BN inert diluent. The maximum temperatures of samples with boron nitride (BN) as a diluent are about 1500–1600°C lower than that of samples with α-SiN and β-SiN as diluents are about 1600–1800°C. Moreover, the newly formed α-SiN contents in the synthesized products with BN as diluent over 90 wt% are much higher than those with α-SiN and β-SiN as diluent about 20–40 wt%. The strip-like α-SiN, rod-like β-SiN grains, and radiative shaped grains can be observed in the synthesized products. Finally, the effect of the diluent on the α-phase content of combustion synthesized SiN is discussed, which provides key guidance for preparing SiN powders with high α-phase content.