Abstract: In order to improve the service life of MgO-MgAl₂O₄ refractories for RH refining,MgO-MgAl₂O₄ refractories were prepared using the sintered magnesia,fused magnesia,fused magnesium aluminate spinel,sintered magnesium aluminate spinel and desilicated zirconia as raw materials,and the calcium lignosulfonate solution as the binder,pressing,drying at 120 ℃ for 72 h,and heat-treating at 1 600 or 1 700 ℃ for 6 h.The effects of desilicated zirconia additions (0,2%,and 4%,by mass) on the phase composition,microstructure and properties of the MgO-MgAl₂O₄ refractories were mainly investigated.The results show that:(1)desilicated zirconia promotes the in-situ formation of CaZrO₃ and (Mg,Zr)(Al,Zr)₂O₄ solid solution in the material.The former hinders the further penetration of molten slag,while the latter enhances the corrosion resistance of MgAl₂O₄ to FeO;(2)with the desilicated zirconia addition increasing from 0 to 4%,the apparent porosity of the material decreases,the bulk density increases and the thermal shock resistance improves.Moreover,with the increase of the heat treatment temperature,the diffusion of Zr element accelerates and the CaZrO₃ formation amount increases;(3)after adding 4% desilicated zirconia and heat-treating at 1 700 ℃,the comprehensive performance of the material is the best,the apparent porosity is 12.2%,the bulk density is 3.14 g·cm^-3,the cold crushing strength is 128 MPa,the thermal shock resistance (1 100 ℃,water quenching) is 12 cycles,and the refractoriness under load is above 1 700 ℃.

Key words: MgO-MgAl₂O₄, desilicated zirconia, (Mg,Zr)(Al,Zr)₂O₄ solid solution, CaZrO₃, thermal shock resistance

摘要： 为提高RH精炼用MgO-MgAl₂O₄质耐火材料的使用寿命,以烧结镁砂、电熔镁砂、电熔镁铝尖晶石、烧结镁铝尖晶石、脱硅锆为原料,以木质素磺酸钙溶液为结合剂,经压制成型、在120 ℃干燥72 h后,再经1 600、1 700 ℃保温6 h热处理,制得MgO-MgAl₂O₄质耐火材料。主要研究脱硅锆加入量(质量分数分别为0、2%、4%)对MgO-MgAl₂O₄质耐火材料物相组成、显微结构及性能的影响。结果表明:1)脱硅锆可促使材料内原位生成CaZrO₃和(Mg,Zr)(Al,Zr)₂O₄固溶体,前者可阻碍熔渣进一步渗透,后者可增强MgAl₂O₄对FeO的抗侵蚀能力;2)随着脱硅锆加入量从0增加至4%(w),材料的显气孔率降低、体积密度增大、抗热震性增强,且随热处理温度的升高,Zr元素扩散加速,CaZrO₃生成量增加;3)当加入4%(w)的脱硅锆,经1 700 ℃热处理后,材料的综合性能最优,此时的显气孔率为12.2%,体积密度为3.14 g·cm^-3,常温耐压强度为128 MPa,抗热震性(1 100 ℃,水冷)为12次,荷重软化温度＞1 700 ℃。

关键词: MgO-MgAl₂O₄, 脱硅锆, (Mg,Zr)(Al,Zr)₂O₄固溶体, CaZrO₃, 抗热震性