Abstract:

Magnesium aluminate spinel hollow sphere heat insulation refractories were prepared by the foaming method using magnesium aluminate spinel hollow spheres (0.6-0.9 and 0.5-0.6 mm) and alumina micropowder (d₅₀=2.38 μm) as main starting materials,alumina sol as the binder,sodium lauryl sulfate as the foaming agent,sodium carboxymethyl cellulose and lauryl alcohol as the foam stabilizer.The effects of the particle size distribution of magnesium aluminate spinel hollow spheres and the alumina sol addition on the bulk density,the strength,the linear change after heating,the linear change on reheating,the thermal conductivity,the phase composition and the microstructure of the specimens were mainly studied.The results show that:(1)with the increasing addition of the 0.5-0.6 mm hollow spheres,the apparent porosity and the linear shrinkage after heating of the specimens gradually decrease,the bulk density,the linear change on reheating,the cold crushing strength and the thermal conductivity gradually increase;(2)when the 0.6-0.9 mm hollow spheres addition is 0,the 0.5-0.6 mm hollow spheres addition is 60 mass% and alumina sol addition is 13.972 7 g per 100 g of the main starting materials,the bulk density of the specimen is 1.13 g·cm^-3,the cold crushing strength is 19.3 MPa,and the linear change on reheating (1 600 ℃×3 h) is 0.22%,the thermal conductivity at 1 200 ℃ is 0.517 W·m^-1·K^-1;(3) with the increase of the alumina sol addition,the apparent porosity and the linear shrinkage after heating of the specimens gradually increase,and the bulk density,the linear change on reheating and the cold crushing strength gradually decrease;(4)when the 0.5-0.6 mm hollow spheres addition is 60 mass% and the alumina sol addition is 16.188 7 g per 100 g of the main starting materials,the apparent porosity is 69.7%,the cold crushing strength is 7.1 MPa,and the linear change on reheating (1 600 ℃×3 h) is 0.05%.

Key words: foaming method, heat insulation refractories, porous materials, magnesium aluminate spinel, hollow sphere

摘要：

以粒度分别为0.6~0.9和0.5~0.6 mm的镁铝尖晶石空心球以及d ₅₀=2.38 μm 的Al₂O₃微粉为主要原料,氧化铝溶胶为结合剂,十二烷基硫酸钠为发泡剂,十二醇和羧甲基纤维素钠为稳泡剂,采用发泡法制备镁铝尖晶石空心球隔热材料,主要研究了镁铝尖晶石空心球粒度级配和氧化铝溶胶加入量对烧后试样致密度、强度、烧后线收缩率、重烧线变化、热导率、物相组成和显微结构等的影响。结果表明:1)随着0.5~0.6 mm空心球加入比例的增大,试样的显气孔率和烧后线收缩率逐渐减小,体积密度、重烧线变化、常温耐压强度和热导率逐渐增大。2)0.6~0.9 mm空心球加入量为0,0.5~0.6 mm空心球加入量为60%(w),每100 g主料中氧化铝溶胶加入量为13.972 7 g时,试样的体积密度为1.13 g·cm^-3,常温耐压强度为19.3 MPa,1 600 ℃保温3 h重烧线变化率为0.22%,1 200 ℃的热导率为0.517 W·m^-1·K^-1。3)随着氧化铝溶胶加入量的增加,试样的显气孔率和烧后线收缩率逐渐增大,体积密度、重烧线变化和常温耐压强度逐渐减小。4)0.5~0.6 mm空心球加入量为60%(w),每100 g主料中氧化铝溶胶加入量为16.188 7 g时,试样的显气孔率为69.7%,常温耐压强度为7.1 MPa,1 600 ℃保温3 h条件下的重烧线变化率为0.05%。

关键词: 发泡法, 隔热材料, 多孔材料, 镁铝尖晶石, 空心球