SYNTHESIS OF SIALONE FROM SHS SYSTEM IN THE MODE OF SOLID-FLAME COMBUSTION

Abstract

The study objective is to synthesize sialon powder in the mode of solid-flame combustion of silicon dioxide (sand) - sodium azide – silicon and aluminum halogenide systems. The task to which the paper is devoted is to find out the initial charge composition (choosing from several sand samples the best in terms of the amount of impurities and the gradation factor), which synthesis gives Si3Al3O3N5 sialon in the mode of solid-flame combustion. Research methods used to obtain and analyze the synthesized product in SHS-Az mode: self-propagating high-temperature synthesis using sodium azide and halogenides in SHS-Az laboratory reactor, X-ray fractional analysis on ARL X'trA-138 diffractometer and the study of microstructure by a scanning electron microscope JSM-6390A. The novelty of the work is in the fact that for the first time SHS-Az method is applied to conduct research on the synthesis of sialon from systems which use bank sand as silicon dioxide. The study results on the synthesis of sialon in the mode of solid-flame combustion show that the final product, in addition to β-Si3Al3O3N5 consists of some more phases such as Si3N4: AlN, Si, naf and Na3AlF6. It is found out that during combustion the formed uniform particles of the product are combined into agglomerate. The average size of the particles that make up the product is 180-230 nm. Conclusions: it is found out that Si3Al3O3N5 sialon is obtained in the mode of solid-flame combustion of silicon dioxide (sand) - sodium azide – silicon and aluminum halogenide systems.