Formation of silicon carbide in the reaction of reduction of silica by carbon

Abstract

In the initial stages of heat treatment of H2SiO3 and sucrose a mixture of highly dispersed defective SiO2 particles and carbon material is formed. Then as the result of contact interparticle interaction of a radical character disintegration (activation) of the carbon particles and envelopment of them by a layer of SiO2 accompanied by deformation of the Si-O-Si bonds occur. Filling of the pores of the carbon material with silicon oxide creates in subsequent higher temperature treatment favorable conditions for formation of SiC. The particles formed as the result of the relatively low-temperature solid-state reaction are non-uniform in composition. Their core consists of uninteracted carbon and after it follow a layer of silicon carbide and an outer layer of SiO2. A switch to the area of high synthesis temperature makes it possible to approach a stoichiometric composition of the silicon carbide.