镁砂细粉对尖晶石轻质耐火材料结构与性能的影响

Influences of magnesia powder on the structure and properties o f light-weight spinel refractories

以电熔尖晶石细粉、烧结镁砂细粉和镁铝尖晶石空心球为主要原料,采用固相烧结法制备了尖晶石轻质耐火材料。借助XRD、SEM等测试手段研究了镁砂细粉和空心球对材料物相组成、显微结构、耐压强度、导热系数等方面的影响。结果表明:少量镁砂细粉(小于5%)的引入,部分固溶于尖晶石中,部分在空心球与尖晶石粉末颗粒之间产生二次尖晶石,促进了空心球与周围粉末颗粒间的结合,减小了材料的孔隙尺寸,降低了导热系数;增加镁砂细粉引入量,有利于促进烧结、提高材料的致密性与耐压强度;控制镁砂细粉引入量小于5%,可制备得到体积密度为1.85~1.98 g/cm^(3)、耐压强度为22.8~27.3 MPa、导热系数为0.256~0.524 W/(m·K)(200~1 000℃)的尖晶石轻质耐火材料。

Light-weight spinel refractories were prepared by solid phase sintering method with fused spinel fine powder,sintered magnesia powder and hollow magnesia alumina spinel balls as main raw materials.The effects of magnesia powder and hollow magnesia spinel balls on phase composition,microstructure,compressive strength and thermal conductivity of refractories were studied.The results showed that the introduction of magnesia powder(less than 5%)promoted the cambination of hollow balls and surrounding particals due to the solid dissolve in spinel and the formation of secondary spinel between hollow ball and spinel powder particles.Increasing the content of magnesia powder promoted the sintering,compactness and compressive strength of refractories.Addition of magnesia powder below 5%was conductive to obtain light-weight spinel refractories with the enhanced compressive strength(22.8~27.3 MPa),the decreased size of pores and thermal conductivity[200~1000℃,0.256~0.524 W/(m•K)].