Phase composition of the products of combustion of ferrosilicon in nitrogen with fluorine-containing additives present

Abstract

The influence of fluorine-containing additives (ammonium fluoride and topaz concentrate) on the phase composition of the products of combustion of ferrosilicon in nitrogen and the morphology of the silicon nitride particles formed is investigated. It is shown that the introduction of 0.5% topaz concentrate into ferrosilicon transfers the autowave combustion regime characteristic for nitriding of ferrosilicon without additives into a layerwise regime. It is established that the high-temperature â modification of silicon nitride â-Si3N4 forms in the presence of ammonium fluoride and a â-Si3N4-based solid solution of the type SiAlON forms in the presence of the topaz concentrate. Self-propagating high-temperature synthesis (SHS) is still a promising method for synthesizing silicon nitride, since the method is characterized by low energy-intensiveness and high productivity. The technology for obtaining silicon nitride was developed by Professor I. P. Borovinskaya and her coworkers [1, 2]. Semiconductor silicon is used as the initial material to synthesize Si3N4. In the SHS process silicon interacts with nitrogen according to the reaction