Abstract: In order to improve the service life of medium frequency furnaces,the alumina-magnesia dry ramming mix was prepared using fused corundum and fused magnesia as main raw materials and CaO as the sintering additive.The effects of the CaO addition (0,0.5%,1%,1.5%,and 2%,by mass) on the phase composition,sintering properties and microstructure of the ramming mix after heat treatment at 1 600 ℃ for 3 h were studied.The results show that an appropriate amount of CaO can promote the sintering of the alumina-magnesia dry ramming mix,and the cold compressive strength is significantly improved.The reason is that CaO reacts with Al₂O₃ to form hexaluminate (CA₆),interposing between corundum and spinel.When the CaO addition is 1%,the ramming mix after heat treatment at 1 600 ℃ has the best comprehensive properties,with the linear expansion rate of 1.38%,bulk density of 2.86 g·cm^-3,apparent porosity of 21.3% and cold compressive strength of 15.2 MPa.

Key words: medium frequency furnace, alumina-magnesia dry ramming mix, sintering properties, compressive strength

摘要： 为提高中频感应炉的使用寿命,以电熔刚玉、电熔镁砂为主要原料,CaO为烧结添加剂,采用捣打成型的方式制备了铝镁质干式捣打料。研究CaO添加量(加入质量分数分别为0、0.5%、1%、1.5%、2%)对铝镁质干式捣打料经1 600 ℃热处理3 h后的物相组成、烧结性能及显微结构的影响。结果表明:适量的CaO能促进铝镁质干式捣打料的烧结,常温耐压强度得到了明显的改善,其原因在于CaO与Al₂O₃反应生成六铝酸钙(CA₆),CA₆穿插于刚玉相与尖晶石相之间,提高了捣打料的强度;当CaO添加量为1%(w)时,经1 600 ℃热处理后的捣打料综合性能最好,其线膨胀率为1.38%,体积密度为2.86 g·cm^-3,显气孔率为21.3%,常温耐压强度为15.2 MPa。

关键词: 中频炉, 铝镁质干式捣打料, 烧结性能, 耐压强度