Green Sealants for the Anodic Oxidation of AlSi Alloys

Abstract The manuscript investigates the use of new sealants in the anodizing process of Aluminium-Silicon (AlSi) alloys with a different content of alloying elements. Particular attention is devoted to sealants with a low environmental impact and reduced health hazards including heavy-metal-free and nontoxic reagents. Metallographic analysis, oxide thickness evaluation, electrochemical noise measurements (ENMs) and neutral salt spray (NSS) tests allow to unveil the complex interplay between the chemical nature of the sealant agent and the corrosion resistance of the obtained anodic layers. It is shown that, depending on the considered AlSi alloy, the different sealing processes can strongly modulate the corrosion resistance of the anodic layers. Overall, new green sealants demonstrate the capability of outperforming conventional toxic reagents. Also, a good accordance between ENMs and NSS tests is observed in the evaluation of corrosion resistance of the investigated materials.