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

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