Development and strategy of Al2O3-MgO castables with high thermal-mechanical stability and insulation ability

Abstract

In this study, alumina bubbles and micro-pore-forming agents were used for the lightweight design of Al₂O₃-MgO castables. The microstructure, phase composition, and physical properties of the castables were analyzed. The results show that the addition of two pore-forming materials could improve the thermal insulation performance and thermal shock stability of the castables. The micro-pore-forming agent modified castable exhibits superior mechanical properties and a minimum thermal conductivity of 0.203 W/(m·K) under the testing temperature of 1000 °C. The appropriate porous structure helps the castable to maintain a certain mechanical strength, reduce its thermal conductivity, disperse thermal stress, and improve the thermal shock resistance. Meanwhile, the multi-channel capillary force from evenly distributed micro-pores could delay the penetration and diffusion of slag. However, the excessive addition of pore-forming materials leads to exorbitant porosity with poor pore structure and distribution uniformity due to the floating of alumina bubbles and the merging of pores, resulting in deleterious effects on the mechanical, thermal, and service properties of the castables. This study contributes to expanding the design and development of Al₂O₃-MgO castable and extending its service life, as well as reducing energy consumption.