Phase composition and morphology of products of combustion of ferrosilicon in nitrogen

The results of a study of silicon nitride phase formation in combustion of ferrosilicon in gaseous nitrogen are reported. It was shown that formation of α-or β-modifications of silicon nitride is basically determined by the composition of the batch for self-propagating high-temperature synthesis. When ammonium chloride was added to the initial ferrosilicon, a combustion product with a high (up to 80%) α-Si3N4 content is formed, while dilution with the final product and magnesium fluoride results in predominant (more than 95%) formation of β-Si3N4. The particle size and shape are a function of the conditions of synthesis and are primarily determined by the temperature and the additives incorporated in the initial alloy.