Abstract: To optimize the phase composition and microstructure of porous anorthite-spinel thermal insulation refractories,thereby enhancing their physical properties,porous anorthite-spinel thermal insulation refractories were prepared via a direct foaming method at 1 200 ℃ for 3 h,using corundum dust,quartz sand,limestone powder and fused magnesia as the main raw materials.The effects of the fused magnesia addition (0,2%,4% and 7%,by mass,respectively) on the microstructure and properties of the resultant materials were investigated.The results show that:(1)the addition of fused magnesia significantly optimizes the phase composition and pore structure of the anorthite-spinel thermal insulation refractories;fused magnesia reacts in-situ with Al₂O₃ to form spinel,thus constructing a ternary composite pore-wall structure composed of anorthite,corundum and spinel;benefiting from the pinning effect of spinel,the pore-wall morphology transforms from an isolated island-like structure into a uniform network structure;(2)with the fused magnesia addition increasing from 2% to 7%,the bulk density of the samples first increases and then decreases,the total porosity first decreases slightly and then increases sharply;the linear expansion rate increases continuously;the cold compressive strength remains basically unchanged at first and then increases sharply,and the thermal conductivity decreases gradually;(3)the sample with 7% fused magnesia exhibits the optimal comprehensive performance.

Key words: porous insulation refractories, anorthite-spinel, direct foaming method, microstructure, compressive strength, thermal conductivity

摘要： 为了优化多孔钙长石-尖晶石隔热耐火材料的物相组成与显微结构,从而提升其物理性能,以刚玉粉尘、石英砂、石灰石粉和电熔镁砂为主要原料,采用直接发泡法经1 200 ℃保温3 h热处理制备了多孔钙长石-尖晶石隔热耐火材料。研究了电熔镁砂添加量(添加质量分数分别为0、2%、4%、7%)对该材料显微结构和性能的影响。结果表明:1)电熔镁砂的引入显著优化了钙长石-尖晶石隔热耐火材料的物相组成及气孔结构,其与Al₂O₃原位反应生成尖晶石,形成了钙长石-刚玉-尖晶石三相复合孔壁结构,尖晶石的“钉扎”效应使孔壁结构由孤岛状转变为均匀网状。2)随着电熔镁砂添加量(w)从2%增至7%,试样的体积密度先升后降,总气孔率先略降低后急剧升高,线膨胀率持续增加,常温耐压强度先基本不变后急剧升高,热导率逐步降低。3)当电熔镁砂加入量为7%(w)时,试样的综合性能最好。

关键词: 多孔隔热耐火材料, 钙长石-尖晶石, 直接发泡法, 显微结构, 耐压强度, 热导率