Abstract

The goal of designing a lightweight wear lining refractory for industrial furnaces has attracted increased attention in the field of refractory materials because a high-porosity lightweight wear lining could produce better heating insulation and thermal spalling resistance. In order to achieve guaranteed slag resistance of prepared lightweight wear lining, fabrication of refractory aggregates with high closed porosity, especially intracrystalline pores, has attracted increasing attention. In the present work, nano-alumina sol had been introduced to form a pile-up of nano–micro double-scale, and its effects on the properties and microstructure of prepared lightweight alumina was investigated. The introduction of nano-alumina sol led to the abnormal grain growth of prepared lightweight microporous alumina, and numerous straight line-distributed intracrystalline pores were observed inside of the abnormally-grew grains. Therefore, resulting in an increase in the closed porosity and decrease in bulk density. A mathematical model was proposed to investigate the formation and microstructure evolution of intracrystalline pores in lightweight microporous alumina. Calculation results showed that the nano–micro double-scale effect created partial regions in which the alumina sol collected, which showed a larger surface stress than other regions. Shrinkage occurred in the partial region simultaneously with grain growth, which led to the formation of intracrystalline cylindrical pores. Moreover, the introduction of nano-alumina sol resulted in a decrease in the closure time of cylindrical pores, then numerous straight line-distributed intracrystalline pores were formed.