Effect of Mg2+, La3+ and Ce4+ on property of mullite ceramics enhanced by andalusite

Mullite ceramic was prepared via solid reaction by fine grinding, isostatic pressing and introducing Mg2+, La3+ and Ce4+with natural andalusite and active alumina as raw materials. The effects of Mg2+, La3+ and Ce4+ on the sintering and thermal shock of mullite ceramic shaped by different methods were investigated. The crystalline phase composition, lattice parameters and microstructure of ceramics were characterized by X-ray diffraction and scanning electron microscopy, respectively. The results indicate that the mullite ceramic with a high density and a good thermal shock resistance can be prepared by doping a certain amount of Mg2+, La3+ and Ce4+, using isostatic pressure, and sintering at 1500℃ for 2 h. The compactness and retention rate of cold compressive strength of mullite ceramic after thermal shock can be improved when MgO of >4% (in mass) is added. The sintering property can be promoted due to La3+ doping. The sintering property and thermal shock resistance of mullite ceramic can be improved due to the doping of a small amount of Ce4+.