Alumina-magnesia castables with 1 5％ ,2.5％, and 3.5％ magnesia, respectively were prepared with fused corundum,sintered corundum,corundum fines,spinel micro powder ( ＜ 5 μm ) ,alumina micro powder ( ＜2 μm) ,calcium aluminate cement ( Secar 71 ) ,and fused magnesia fines as starting materials The bulk density,apparent porosity,strength,permanent linear change on heating after heat treatment at 1 500 ℃ for 3 h were determined,the resistance to blast furnace slag was also investigated at 1 500 ℃ for 3 h.The results indicate that with the increase of magnesia addition ,the apparent porosity of the specimen after firing increases ,the strength and the slag resistance decrease It is resulted from the overall volume expansion caused by the formation of spinel when magnesia reacts with alumina at elevated temperatures Thus,the appropriate addition of magnesia is about 2 5％.%以电熔刚玉、烧结刚玉、刚玉细粉、尖晶石微粉(<5μm)、氧化铝微粉(<2μm)、铝酸钙水泥(Secar 71)、电熔镁砂细粉为主要原料,制备了镁砂加入质量分数分别为1.5%、2.5%、3.5%的铝镁浇注料.测定1 500℃3 h处理后试样的体积密度、显气孔率、强度和加热永久线变化率,并在1 500℃3 h条件下进行抗高炉渣侵蚀试验.结果表明:随着镁砂加入量的增加,材料烧后的显气孔率增大,强度降低,抗高炉渣侵蚀性能下降.这主要是电熔镁砂在高温下与氧化铝反应生成尖晶石产生体积膨胀所至,因此,镁砂的加入质量分数以2.5%为宜.
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