Synthesis of β-SiC Using Nanofibrous Carbon

Abstract

The synthesis and study of the characteristics of β-phase silicon carbide powder is carried out. The compound is obtained by combining endothermic and exothermic reactions (carbothermic reduction of silicon dioxide and synthesis from simple substances) in an induction furnace in an atmosphere of nitrogen and carbon monoxide (CO). Nanofibrous carbon (NFC) is used as the reducing agent and carbide-forming reagent. This carbon agent is obtained as a result of the decomposition of light hydrocarbons. NFC is characterized by a high specific surface area (~150 m²/g) in comparison, for example, with carbon black (~50 m²/g). NFC is a fairly pure material and the impurity content in it does not exceed 1 wt %. Optimization of the synthesis conditions made it possible to obtain a single-phase product: cubic silicon carbide β-SiC. The powder had an average particle size of ~4 μm and a specific surface area of 7.7–8.4 m²/g. The resulting silicon carbide barely oxidizes when heated to 1000°C. Completion of the synthesis reaction is achieved for samples whose charge contained NFC, silicon oxide, and silicon powder in a molar ratio of 4 : 1 : 1, respectively. The optimal synthesis temperature is 1700–1900°C.