Abstract: To overcome the harsh operating environment of refractories used in RH refining furnaces,magnesia-zirconia spinel was pre-synthesized using high-grade magnesite,desilicated zirconia,and MgAl₂O₄ as raw materials.Then MgO-ZrO₂-MgAl₂O₄ refractories were prepared by mixing the pre-synthesized spinel with fused magnesia of different particle sizes,molding,drying,and calcining.The effect of the pre-synthesized magnesia-zirconia spinel addition (10%,20%,and 30%,by mass) on the properties of the MgO-ZrO₂-MgAl₂O₄ refractories was studied.The results show that:(1)with the increase of the pre-synthesized magnesia-zirconia spinel addition,the bulk density of MgO-ZrO₂-MgAl₂O₄ refractories gradually increases,the apparent porosity,the linear shrinkage rate,and the cold modulus of rupture decrease gradually,the permeation resistance is improved gradually,and the corrosion resistance slightly decreases;(2)when the pre-synthesized magnesia-zirconia spinel addition is 20%,MgO-ZrO₂-MgAl₂O₄ refractories have a lower linear expansion coefficient and exhibit optimal fracture toughness and thermal shock resistance.Overall,the optimal addition of the pre-synthesized magnesia-zirconia spinel is 20%.

Key words: RH refining furnaces, MgO-ZrO₂-MgAl₂O₄, pre-synthesized magnesia-zirconia spinel, thermal shock resistance, linear expansion coefficient

摘要： 为了克服RH精炼炉用耐火材料苛刻的使用环境,以特级菱镁矿、脱硅锆和镁铝尖晶石为原料预合成镁锆尖晶石,然后与不同粒级的电熔镁砂混合、成型、烘干、煅烧制备出MgO-ZrO₂-MgAl₂O₄质耐火材料。研究了预合成镁锆尖晶石加入量(加入质量分数分别为10%、20%、30%)对MgO-ZrO₂-MgAl₂O₄质耐火材料性能的影响。结果表明:1)随着预合成镁锆尖晶石加入量的增加,MgO-ZrO₂-MgAl₂O₄质耐火材料的体积密度逐渐增大,显气孔率、线收缩率和常温抗折强度逐渐减小,抗渗透性逐渐提高,而抗侵蚀性略微降低。2)当预合成镁锆尖晶石加入量(w)为20%时,MgO-ZrO₂-MgAl₂O₄质耐火材料具有较低的线膨胀系数,并表现出最优的断裂韧性和抗热震性。综合来看,预合成镁锆尖晶石的最佳加入量(w)为20%。

关键词: RH精炼炉, MgO-ZrO₂-MgAl₂O₄, 预合成镁锆尖晶石, 抗热震性, 线膨胀系数