Effect of sand-blasting stripping and sol-gel sealing on the performance of Tartaric-Sulphuric Acid anodizing layers formed on clad and bare AA2024

摘要

AA2024 T3 aluminium alloy is widely used in the aircraft industry due to its high specific strength and light weight. High mechanical properties are due to enrichment of aluminium matrix in copper which reduces the corrosion protection by forming microscopic galvanic couples. In order to improve its corrosion resistance, AA2024 is protected by cladding pure aluminium layer and/or anodizing. The anodizing traditionally performed in chromic acid bath and sealed in aqueous potassium dichromate solution provides layers affording excellent corrosion protection. Nevertheless, because of toxicological and environmental concerns related to Cr~Ⅳ use, it will be forbidden for aeronautical applications in 2017. New alternatives, such as tartaric-sulphuric acid anodizing (TSA), have already been used at an industrial level.