加入脱硅ZrO_2微粉对MgO-Cr_2O_3材料性能的影响

Effect of desiliconized ZrO_2 micropowder on properties of MgO-Cr_2O_3 refractories

为了提高MgO-Cr2O3材料的性能,以质量分数为60%的电熔镁铬砂、27%的南非铬矿粉、13%的烧结镁砂为基础配比,外加脱硅ZrO2微粉(其质量分数分别为1.5%、2%、2.5%和3%)制备了MgO-Cr2O3材料。研究引入ZrO2对MgO-Cr2O3材料体积密度、显气孔率、耐压强度、高温抗折强度和抗RH精炼渣侵蚀性的影响。结果表明:1)引入ZrO2显著提高了MgO-Cr2O3材料的体积密度、常温耐压强度和高温抗折强度。2)ZrO2与熔渣中的CaO发生反应,生成高熔点的化合物CaZrO3,堵塞气孔,阻止熔渣进一步渗透,提高了MgO-Cr2O3材料的抗渣性;同时反应吸收CaO,使熔渣的碱度降低,黏度增大,这也有利于提高镁铬砖的抗渣侵蚀性。综合考虑MgO-Cr2O3材料的各项性能,脱硅ZrO2微粉的最佳外加量为2.5%(w)。

MgO-Cr2O3 refractories were prepared based on the formulation of 60% （in mass, the same hereinafter） fused magnesia chrome sand,27% chrome ore powder from South Africa,13% sintered mag- nesia,extra adding 1.5% ,2% ,2.5% ,and 3% desiliconized ZrO2 micropowder,respectively,to improve the properties of MgO-Cr2O3 refractories. Effects of the ZrO2 additions on bulk density, apparent porosity, crushing strength,hot modulus of rupture,and resistance to RH degasser slag were investigated. The results show that：（1）introduction of ZrO2 improves the bulk density, cold crushing strength and hot modulus of rupture of the MgO-Cr2O3 refractories obviously; （2） ZrO2 reacts with CaO in the slag forming CaZrO3 with high density and high melting point, blocking pores and preventing the further slag penetration;mean- while, the reaction consumes CaO, decreasing the basicity and increasing the viscosity of molten slag ,thus increasing the slag resistance of the refractories. Therefore, take all properties into account, the optimal ZrO2 addition is 2.5%.