Silicon-silicon carbide (Si-SiC) composite powders were produced by in-situ magnesiothermic self-combustion synthesis in a static argon atmosphere, using precursors of carbon, magnesium and either rice husk ash (RHA) or natural sand. The description of the reaction involves initial the combustion reaction, the phase conversion through the product, and the cooling rate. The adiabatic temperature (Tad), the enthalpy of the reaction (ΔH) and the equilibrium composition of the reacting species were calculated. Pure Si-SiC powders were obtained by leaching with a solution of HCl: CH3COOH followed by HF : H2O solution. Both the experimental results and the thermodynamic analysis indicated that the exothermic effect on the conversion of Mg2SiO4 had a large influence on the resultant Si-SiC composite.

Keywords: Combustion synthesis, Si-SiC composite, RHA, Natural sand, Silica, leaching