Preparation Mechanism And Properties Of SiC Matrix Composite Ceramics Powders By Rice Husk Ash

This paper was carried out on a base of industrial waste rice husk ash’s(RHA) multipurpose use. At present, some of the Biomass power plants generate electricity by the use of rice husk’s combustion, from which large amounts of RHA are produced. Therefore, how to make the best use of RHA, reduce its pollution and form the recycling economy industrial chain of Biomass-Generate electricity-Raw materials gradually becomes a serious problem to the electric power plant.Using carbon black and RHA from the plant as raw materials, Sialon/SiC and Si3N4/SiC ceramic composite powder were made by the carbon thermal reduction. By the means of DTA-TG, XRD and SEM, the influence of different ratios of raw materials and synthesis temperature on composite powder’s phase composition and microstructure were studied, and then the reaction mechanism was analyzed. In addition, the resistance to oxidation of composite powder was tested. At last, the influence of impurity elements(Al, Fe, Ca) on composite powder’s phase composition and microstructure were also researched, which included Al2O3, Fe2O3and CaO, unlike the before, this composite powder was prepared by man-made RHA. The main conclusions are as follows:(1) As to Sialon/SiC and Si3N4/SiC composite powder prepared by the carbon thermal reduction with carbon black and RHA, they could be made when the synthesis temperature was between1500℃to1580℃and SiO2:C mole ratio between1:1with1:6. The synthetical β-Si3N4was short columnar, with the length of about4-7μ m, and the phase of SiC has irregular form of long strip. The phases’growth was interpenetrating and interlaced. The synthesis composite powder was susceptible to temperature and carbon content.(2) Sialon/SiC composite powder, which was synthesized by carbon black and RHA at high temperature, was going to oxidation at1118℃in the air and the weight increment13.68%; Si3N4/SiC composite powder’s was going to oxidation at603℃in the air and the weight increment13.2%.(3) As to the composite powder synthesized by man-made RHA, when the content of Al2O3was between1.12%and26.62%, the synthesis temperature was1500℃, we found that the phase of Sialon generated, and disappeared when the temperature raised to1550℃; when the content of Fe2O3was between0.67%and10.5%, the temperature was1500℃and1550℃, we found that the forming temperature of SiC reduced greatly, and had irregular form of long strip; when the content of CaO was between1.06%and15.1%, the temperature was1500℃, we found that the CaO had few effects on composite powder’s phase, and the Si3N4’s shape was short columnar.