Anodising of 2024-T3 aluminium alloy in electrolyte of sulphuric- boric-phosphoric mixed acid containing cerium salt as corrosion inhibitor
(Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Street, Shiraz 7134851154, Iran)
Abstract: The effect of cerium salt as an inhibitor in anodising of the 2024-T3 aluminium alloy was studied. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy was used to study the surface composition of the alloy before and after surface preparation. A mixed electrolyte of 10% sulphuric acid, 5% boric acid and 2% phosphoric acid containing 0.1 mol/L cerium sulphate salt was used as the anodising electrolyte. Sealing treatment was also done in boiling water and molten stearic acid. Electrochemical impedance spectroscopy and salt spray techniques were performed in order to investigate the corrosion behaviour and durability of the oxide films, respectively. It was concluded that the presence of cerium ions in anodising electrolyte resulted in the increase in homogeneity, the rate of oxide film growth and also the thickness of the oxide layer, owing to the high oxidising power of cerium ion.
Key words: aluminium alloy; anodising; mixed acid; cerium salt; inhibitor