Convenient preparation of calcium hexaluminate based castables with low thermal conductivity and sufficient strength

Calcium hexaaluminate (CA 6 ) based castables with low thermal conductivity and sufficient strength were conveniently prepared by foaming and incorporating alumina bubbles. The pores are derived from stabilizing the liquid foams by the surfactant (air‐entraining agent) and hollow structure of alumina bubbles. The thermal and physical properties of CA 6 based castables depended on the approaches producing pores as well as their quantity, morphology, and distribution. CA 6 based castables with the thermal conductivity of .384–.491 W/(m∙K) tested at 800°C and the cold crushing strength of 49.4–99.5 MPa after firing at 1 300°C, exhibited promising application prospects as insulation linings used for the skid post and beam in the reheating furnace.