Influence of the Gas Atmosphere on the Formation of SiC Fibers upon the Siliconization of Carbon Felt

Experimental data on the effect of the ambient atmosphere (a vacuum or argon) on the phase composition of silicon carbide fibers formed upon the siliconization of carbon felt are presented. The major phases produced in the siliconization of carbon felt are β-SiC (3C) in vacuo and α-SiC (6H) in the argon atmosphere. When carbon felt is siliconized in vacuo, residual silicon is present on the surface of the silicon carbide felt fibers. The ambient atmosphere determines the nature of the siliconization process at 1650°C: in vacuo, SiC is formed due to the reaction of carbon fibers with the silicon melt wetting them, while in argon, it is formed due mainly to the reaction with vaporous silicon.