Effect of the Superfine SiO<sub>2</sub> Powder Content on the Properties of SiC Composites

Abstract

In this paper, silicon carbide materials bonded with superfine SiO2 powder were produced using silicon powder, superfine SiO2 powder and different grain grade silicon carbide as raw materials. At the condition of the same content of silicon powder, the effect of the superfine SiO2 powder content on properties of silicon carbide materials after sintered at 1450°C for 3 h in air atmosphere was studied by means of SEM and other analysis methods. The results showed that silicon powder contributes to both sintering by liquid state and plastic phase combination to improve the strength of samples. When the superfine SiO2 powder content is lower than 3.5%, the density and strength of samples increase and porosity decrease with increasing superfine SiO2 powder content. However when the superfine SiO2 powder content is higher than 3.5%, the density and strength of samples decrease and porosity increase with increasing superfine SiO2 powder content. At the same time, sample with 3.5% superfine SiO2 powder has the best oxidation resistance property at 1100°C.