Effect of catalyst and process parameters on the production of silicon carbide from rice hulls

Several routes for the production of SiC by pyrolysis of rice hulls have been examined. Under reducing and proper reaction conditions, four distinct processes have been identified; these are, decomposition of silica and cellulose and the formation of SiC particles and whiskers. The effectiveness of sodium silicate as a catalyst on maximisation of SiC yield has been discussed. The dependence of SiC yield on the pyrolysis temperature and atmosphere has been described. The reaction products were investigated by XRD, EDS, and SEM. Optimum conditions for the highest SiC yield were determined, and mechanisms for the nucleation and growth of SiC whiskers were discussed. (C) 1998 Elsevier Science Limited and Techna S.r.l. All rights reserved.