Anodizing of 2024-T3 Aluminum Alloy In Sulfuric Acid Electrolyte Modified By Boric And Phosphoric Acid And Study Of Corrosion Behavior

摘要

Corrosion resistance of 2024-T3 Aluminum alloy was improved by anodizing in mixed electrolyte containing 10 wt% sulfuric acid, 5 wt% boric acid and 2 wt% phosphoric acid. Anodizing process was performed for 20 minutes under current density of 1 mA/Cm2 followed by sealing treatment which carried out in boiling water for 30 minutes. Samples were dipped in aqueous media containing 3.5 wt% of NaCI for different periods of time to investigate durability. Electrochemical impedance spectroscopy technique was used to study the corrosion behavior of the anodized alloy. Electrochemical parameters of the barrier and porous layers were determined separately using an appropriate equivalent circuit. Tafel plot examination was also used for verification of the results. It was revealed that the anodizing treatment of 2024-T3 Aluminum alloy in sulfuric/boric/phosphoric acid provides better corrosion resistance and durability in comparison with the anodizing treatment in phosphoric acid or su If uric/boric acid solutions. This electrolyte can be a suitable replacement for chromate baths which are generally used in anodizing of Aluminum alloys.