Preparation of Anorthite Ceramic Coatings from Purified Aluminum Dross

This investigation details the utilization of aluminum dross as a primary precursor for the synthesis of slag-based anorthite (CaAl2Si2O8) ceramic. To mitigate the deleterious effects of salts and impurities contained in the dross on the final mechanical and chemical properties, a multi-step hydrothermal purification (washing) process was employed. This resulted in a refined Al2O3-MgO-SiO2 oxide system. The synthesized anorthite was applied as a protective layer on commercial mullite substrates to enhance resistance against degradation by molten aluminum–magnesium alloys. This study characterizes the chemical, mineralogical, and thermodynamic interactions at the interface, demonstrating that this coating provides a robust barrier through the formation of stable reaction products.