电熔镁砂加入量对钢包用铝镁质透气砖性能的影响

为了实现钢包用透气砖的无铬化,以板状刚玉(6～3、3～1、≤1mm)为骨料,板状刚玉细粉(≤0.044mm)、α-Al2O3微粉(≤5μm,d50=2.01μm)、镁铝尖晶石细粉(≤0.044mm)、电熔镁砂细粉(≤0.044mm)为基质,以纯铝酸盐水泥为结合剂,将骨料和基质的质量比固定为70:30,通过研究电熔镁砂细粉加入量(其质量分数1％、2％、3％、4％、5％)对铝镁质透气砖性能的影响,研制了铝镁质透气砖,与铬刚玉质透气砖的性能进行了对比.结果表明:加入质量分数2％的电熔镁砂细粉,试样的力学性能提高,抗热震性增强；进一步增大电熔镁砂细粉的加入量,由于原位镁铝尖晶石的生成量过多,微裂纹发展成为破坏性裂纹,试样的强度急剧降低,体积密度下降,试样的加热永久线变化增大,抗热震性先增强后减小,高温抗折强度下降.通过铬刚玉质透气砖和铝镁质透气砖性能及现场试用情况的对比,认为铝镁质透气砖可代替铬刚玉质透气砖使用,实现透气砖的无铬化.

Effect of fused magnesia addition on properties of alumina-magnesia purging plugs for ladle

In order to replace the chrome-containing purging plugs for ladle,alumina-magnesia purging plugs were prepared using tabular corundum(6-3,3-1 and ≤1 mm) as aggregates,tabular alumina powder(≤0.044 mm),α-Al2O3 micropowder(≤5 μm,d50=2.01 μm),spinel(≤0.044 mm) and fused magnesia powder(≤0.044 mm) as matrix,and calcium aluminate cement as binder,and keeping the mass ratio of aggregate and matrix at 70:30.Effects of fused magnesia powder additions(1%,2%,3%,4% and 5% in mass) on properties of purging plugs were researched.The properties of produced alumina-magnesia purging plugs were compared with those of chrome corundum purging plugs.The results show that:(1)adding 2% of fused magnesia powder can improve the mechanical properties and thermal shock resistance;(2)when further increasing the addition of fused magnesia powder,because of excessive formation of in-situ spinel,microcracks become destructive cracks,the strength of the specimen decreases drastically,bulk density and hot modulus of rupture decrease,permanent change in dimensions on heating increases,thermal shock resistance enhances firstly and then declines.By comparing the properties and on-site trials of chrome corundum and alumina-magnesia purging plugs,it is regarded that the latter can replace the former chrome-containing purging plugs.