Effect of particle size and shape of diluent on the reaction process of combustion synthesis of α‐Si3N4 powder

Abstract

Abstractα‐Si3N4 powder was prepared by combustion synthesis using different particle sizes and shapes of Si3N4 diluent. The effects of different diluents on combustion temperature, phase composition, and microstructure of the product were investigated. The role of diluents in combustion synthesis is discussed. When no ammonium salt was added, because of the higher reaction temperature, the phase transformation of the fine particle diluent with the best barrier effect was also enhanced, and the α content of the product was the lowest. When the ammonium salt is added, the liquid phase Si content decreases at high temperatures, the lower reaction temperature and the Si3N4 generated before Si melting make the barrier effect of the diluent fully play. Finally, Si3N4 powder with 86% α content was synthesized by combustion with 2 μm Si3N4 diluent.