Effects of pelletization of reactants and diluents on the combustion synthesis of Si3N4 powder

Reactants were pelletized, and then combustion synthesis of Si₃N₄ powder was achieved under the N₂ pressure of 3.0 MPa. Effects of the pelletization of reactants and Si₃N₄ diluents on the combustion process parameters and the characteristics of products were studied. The combustion mode of single reactant pellet was preliminarily discussed. The results indicated that the combustion reaction of single pellet was layer-by-layer from the surface to the core, which led to two peaks on the combustion temperature variation waves. With increasing the diluents content, the morphologies of Si₃N₄ particles changed from short rods into equiaxed grains, and residual Si in the final products obviously decreased. Single phase β-Si₃N₄ powder mainly contained equiaxed grains was prepared when 58 wt.% diluents was added.