Effect of the diluent on combustion synthesis of silicon nitride.

Si3N4 powders were prepared by combustion synthesis with 1‐ and 3‐μm α‐Si3N4, β‐Si3N4 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‐Si3N4 and β‐Si3N4 as diluents are about 1600–1800°C. Moreover, the newly formed α‐Si3N4 contents in the synthesized products with BN as diluent over 90 wt% are much higher than those with α‐Si3N4 and β‐Si3N4 as diluent about 20–40 wt%. The strip‐like α‐Si3N4, rod‐like β‐Si3N4 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 Si3N4 is discussed, which provides key guidance for preparing Si3N4 powders with high α‐phase content. [ABSTRACT FROM AUTHOR]