Effect of Molar Ratio of MgO/Al₂O₃ on the Performance of MgO-Al₂O₃-Fe₂O₃ Composite

The MgO-Al₂O₃-Fe₂O₃ composite was prepared at 1600°C for 3h with magnesia powder and alumina powder as raw materials and with ferric oxide powder as additive. The effect of the molar ratio of MgO/Al₂O₃ on the sintering and thermal shock resistance of the composite materials was studied. The results showed that increasing the molar ratio of MgO/Al₂O₃ could improve the densification of the Al₂O₃-Fe₂O₃ composites, with the molar ratio of MgO/Al₂O₃ increased from 3 to 5, densification of the composites didn't increased but decreased. The optimum molar ratio of MgO/Al₂O₃ of the Al₂O₃-Fe₂O₃ composite is equal to 3, the sample MA-3 exhibits better sintering densification and thermal shock resistance. Its primary crystal phases are spinel and periclase, and less amount of sosoloid 20MgO·19Al₂O₃·Fe₂O_3. So, the MgO-Al₂O₃-Fe₂O₃ composite is acceptable for application in cement rotary kiln linings and high temperature gas filter support.