The plasma arc production of Si-based ceramic whiskers

Abstract

Silicon-based ceramic whiskers, such as silicon carbide and silicon nitride, were produced in a plasma arc reactor. Silicon monoxide gas was generated by reacting briquettes of silica and carbon according to the following reaction: SiO2(s or l) + C(s) = SiO(g) + CO(g). The effects of operating variables on the production of silicon monoxide are discussed. The silicon monoxide gas was then back-reacted with carbon monoxide to produce silicon carbide whiskers according to the following reaction: SiO(g) + 3CO(g) = SiC(s) + 2CO2(g). In the presence of nitrogen, the product contained some silicon nitride and silicon oxynitride whiskers. The effects of gas composition and flow rate, crucible mass, and alkali additions on the amount and morphology of the whiskers were determined. It is concluded that the whiskers grew by a vapor-liquid-solid mechanism.