Crystal Growth in the Combustion Synthesis of α‐Si 3 N 4 Using Si with Different Particle Sizes

In this present work, Si 3 N 4 powders with high α‐phase contents and distinct crystal morphologies were prepared via a promising approach of combustion synthesis (CS), using Si powders with different particle sizes as reactants. The influence of Si particle size on phase composition and crystal morphologies in the products was systematically investigated. Two unique crystal morphologies, radial‐spheroidal‐cluster and flowerlike, were observed in the Si 3 N 4 products. The crystal growth mechanisms of Si 3 N 4 granules in the CS system with disparate Si have been proposed based on experiments and thermokinetic calculations. As conclusion, the α‐phase content in the final product was synergetically dominated by the vaporization process of Si particles and the α–β phase transformation of Si 3 N 4 during the after‐burn period. Si 3 N 4 powders with high α‐phase content can be obtained from Si powders with an appropriate particle size.