Study on mullitization of sillimanite group minerals and its effect on properties of the Al2O3‐SiC‐C gunning material

Abstract

AbstractThis study aimed to compare and summarize the mullitization mechanism of the sillimanite group minerals and investigated its effect on the mechanical properties of Al2O3‐SiC‐C gunning materials. By comparing the phase composition and microstructure of kyanite, andalusite, and sillimanite at different temperatures, the mullitization mechanism of sillimanite group minerals was clarified. Furthermore, the Al2O3‐SiC‐C gunning materials with sillimanite group minerals addition were prepared by bauxite and fused brown corundum as aggregates, fused white corundum (≤0.045 mm), SiC (≤0.075 mm), α‐Al2O3 (≤10 µm), pitch sphere, SiO2 micropowder (≤2 µm) as a matrix, and silica sol as a binder. Then, the effect of the addition of sillimanite group minerals on the mechanical properties of Al2O3‐SiC‐C gunning materials was characterized. The results indicate that kyanite requires the lowest temperature for mullitization compared to andalusite and sillimanite. The mullitization process involves the migration of Al3+ and Si4+, resulting in a decrease in the lattice constant of sillimanite group minerals followed by the production of mullite and SiO2. Incorporating sillimanite group minerals into Al2O3‐SiC‐C gunning materials effectively controls their linear change rate after firing while enhancing their mechanical properties. Notably, the addition of kyanite yields superior performance in Al2O3‐SiC‐C gunning materials.