Study of the possibility of obtaining sialon powder in the mode of self-propagating high-temperature synthesis using SiO2 of different fractions

10.25712/ASTU.1811-1416.2025.03.006

Abstract

The article presents the results of studies of the possibility of obtaining sialon powder using the azide technology of self-propagating high-temperature synthesis. Sialon was obtained by burning a reaction mixture consisting of sodium azide NaN₃, aluminum fluoride AlF₃ and silicon oxide SiO₂. Silicon oxide was used in the form of quartz sand of two fractions (0.8-1.2 mm and 0.1-0.3 mm) and aerosil. The use of quartz sand of the 0.1-0.3 mm fraction resulted in obtaining a product with the highest amount of the sialon phase (55%). In addition, sialon of the composition Si_1.96Al_0.04O_1.04N_1.96 was synthesized already at a temperature of 1200ºС, which is several hundred degrees lower than the temperature of obtaining sialons using other technologies. The microstructure of the target product, when using quartz sand with a particle size of 0.1-0.3 mm in the SiO₂-NaN₃-AlF₃ charge, consisted of equiaxed particles of sialon Si_1.96Al_0.04O_1.04N_1.96, sodium hexafluoroaluminate Na₃AlF₆ and silicon oxide SiO₂. The average particle size of sialon was in the range from 100 to 150 nm. In the product synthesized from the batch containing aerosil, sialon phases of a different composition were found: Si_1.6Al_0.4O_1.4N_1.6 (8%) and SiAlON (12%). This indicates that different fractions of SiO₂ in the initial batch affect the phase composition of not only the entire final product, but also the composition of sialon.