Efficiency of anodising of Al-Cu alloy in sulphuric acid at low potentials

The effect of copper on anodising of aluminium in sulphuric acid at low potentials has been examined for a sputtering-deposited Al-0.75 at.-%Cu alloy, using ion beam analysis and transmission electron microscopy. The aim was to determine the relationship between the potential and oxygen generation, with copper in the anodic film in either a metallic or oxidised form. The findings revealed that similar to 30 to 40% of the cell charge is used in oxygen generation at potentials between 2 and 8 V( SCE). The charge of Al3+ ions in the film indicated overall efficiencies of film growth that increased from 23 to 41% over the potential range.