Growth of silicon carbide whiskers in FexSiy flux

A novel method to synthesize SiC whiskers by heating FexSiy (FeSi, FeSi2 and Fe5Si3) in graphite crucible without using catalyst is presented. The SiC whiskers grew on the inner wall of the crucible above the top level of melted FeSi and FeSi2 (not for Fe5Si3) after heating at 1600 °C for 3 h under stationary argon of 0.11 MPa and fast cooling. The formation of SiC whiskers is attributed to the reaction of Si in FeSi and FeSi2 melt films wetting and spreading on the inner wall of the crucible with C dissolved from the graphite crucible (LS process). Besides SiC whiskers, Fe5Si3 was also found in the final product in FeSi2–C system, based on which a reaction equation is assumed and no whiskers formation in Fe5Si3–C system is explained. The explanation takes into consideration the carbon solubility in FexSiy melts, and high carbon solubility in Fe5Si3 melt is believed the reason why SiC whiskers did not come up in Fe5Si3–C system.