Effect of submicron spinel powders on the microstructure evolution and properties of alumina‐based refractory castables

Abstract The physical properties, including flow value, apparent porosity, and mechanical strength, increased significantly with submicron spinel contents in this study. The excellent physical properties can be attributed to the close‐packed microstructure and high bonding strength between spinel and aggregates/matrix. Additionally, the submicron spinel powders promoted the formation of tabular CA ₆ grains that generated a cross‐linked structure and enhanced the mechanical properties. The microstructures of corroded castables suggested that submicron spinel powders contributed to the formation of a continuous and thick spinel layer at the slag–refractory interface and subsequently improved the slag resistance of the castables.