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

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