Effect of Al₂O₃ and TiO₂ Addition Amount on Properties of MgO-based Ceramics by Coprecipitation Method

MgO particles coated with Al₂O₃ and TiO₂ precursors, respectively, were prepared by coprecipitation method and sintered at 1 450℃ for 2 h, and then the MgO-based ceramics were obtained. The effects of the addition amount of Al₂O₃ and TiO₂ on the phase composition, sintering performance and thermal shock resistance of the ceramics were investigated. The results show that the ceramics added with Al₂O₃ mainly consisted of periclase and MgAl₂O₄ phases. With increasing Al₂O₃ addition amount, the MgAl₂O₄ phase content increased, the linear shrinkage rate and the number of thermal shock cycles first increased and then decreased, and the bulk density increased. The ceramics added with TiO₂ was mainly composed of periclase, Mg₂TiO₄ and MgTiO₃ phases. With increasing TiO₂ addition amount, the content of Mg₂TiO₄ phase and MgTiO₃ phase increased, the linear shrinkage rate and bulk density first increased and then decreased, and the number of thermal shock cycles first increased and then remained stable. When the mass fractions of Al₂O₃ and TiO₂ were 6%, 4%, respectively, both the sintering performance and thermal shock resistance of the ceramics were the best.