α-SiC Nanowires Synthesized by Vapor-Phase Siliconization of Carbon Felt

Abstract

This study examines the synthesis of α-SiC nanowires from the gas phase during the siliconization of carbon felt in an inert argon atmosphere. It is shown that the siliconization of carbon felt without the use of a metallic catalyst is accompanied by a series of sequential and parallel redox reactions, including the formation of gaseous SiO, the formation of silicon dioxide (SiO₂) in the free volume of the felt, and the growth of α-SiC nanowires on the resulting β-SiC fibers. It was established that the intermediate formation of silicon dioxide plays a key role in the growth of α-SiC nanowires. Silicon dioxide forms through the interaction of gaseous SiO with residual oxygen and through the local oxidation of the surface of β-SiC fibers in the silicon carbide felt. Subsequently, SiO₂ is reduced by carbon and/or carbon monoxide to form SiC, which promotes nanowire growth and the formation of a cotton-like three-dimensional structure. The obtained results indicate that the formation of α-SiC nanowires in porous carbon matrices such as carbon felt is governed not only by the direct carbothermal conversion of silicon dioxide, but also by complex redox reactions occurring in the gas phase.