Synthesis of SiC from rice husks catalysed by iron, cobalt or nickel

Abstract

The synthesis of SiC (both powder and whiskers) was carried out from rice husks with and without the use of catalysts (iron, cobalt and nickel). The introduction of the catalyst increased the reaction rate, the yield becoming up to three times that for the uncatalysed reaction, and increased the proportion of β-phase from 95% to 99%. The general behaviour of the three catalysts was very similar, although nickel was the most effective from the point of view of reaction rate, and cobalt in producing larger crystal size. Analysis of the evolution of reaction rate, morphology of the whisker formed, evolution of gases during reaction, crystal size and intermetallic phases, led to a reaction mechanism based on the formation of an M-Si-C liquid phase which is essential for the nucleation and growth of the SiC whiskers.