Effect of potassium permanganate on corrosion performance of the anodized coating on 2024-T3 aluminum alloy

Effects of different concentrations of potassium permanganate, as a corrosion inhibitor, on morphology, composition, thickness and corrosion behavior of anodic film of 2024-T3 aluminum alloy formed in 17% sulfuric acid were investigated. Surface morphology and chemical composition of oxide film were studied using field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. Potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were conducted to assess the corrosion performance of the coatings. These analyses have shown that presence and addition of potassium permanganate during anodizing process results in more compact and thicker anodic film with smaller pore size. In addition Corrosion results have shown that using permanganate ions increased corrosion resistance of the anodic layer, increasing the potassium permanganate in anodize solution, would caused a coating with higher corrosion resistance. The quantity of the corrosion improvement was about 25% and 85% for 0.01 and 0.1M, respectively.