The effect of the addition of TiO2 in the preparation of Al2O3-SiC composite powder by SHS Process

Abstract

<TEX>$Al_2O_3-SiC$</TEX> and <TEX>$Al_2O_3-SiC$</TEX>-TiC composite powders were prepared by SHS process using <TEX>$SiO_2,\;TiO_2$</TEX>, Al and C as raw materials. Aluminum powder was used as reducing agent of <TEX>$SiO_2,\;TiO_2$</TEX> and activated charcoal was used as carbon source. In the preparations of <TEX>$Al_2O_3-SiC$</TEX>, the effect of the molar ratio in raw materials, compaction pressure, preheating temperature and atmosphere were investigated. The most important variable affecting the synthesis of <TEX>$Al_2O_3-SiC$</TEX> was the molar ratio of carbon. Unreactants remained in the product among all conditions without compaction. The optimum condition in this reaction was <TEX>$SiO_2$</TEX>: Al: C=3: 5: 5.5, 80MPa compaction pressure under Preheating of <TEX>$400^{\circ}C$</TEX> with Ar atmosphere. However there remains cabon in the optimum condition. The effect of <TEX>$TiO_2$</TEX> as additive was investigated in the preparations of <TEX>$Al_2O_3-SiC$</TEX>. As a result of <TEX>$TiO_2$</TEX> addition, <TEX>$Al_2O_3-SiC$</TEX>-TiC composite powder was prepared. The <TEX>$Al_2O_3$</TEX> powder showed an angular type with 8 to <TEX>$15{\mu}m$</TEX>, and the particle size of SiC powder were 5~<TEX>$10{\mu}m$</TEX> and TiC powder were 2 to <TEX>$5{\mu}m$</TEX>.