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

Abstract

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 ∼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.

Keywords:

• Aluminium
• Copper
• Anodising sulphuric acid
• Anodic films
• Ion beam analysis

Acknowledgements

The authors are grateful to the Engineering and Physical Sciences Research Council (UK) for the support of the LATEST2 Programme Grant and to The British Spanish Society for provision of a scholarship to Beatriz Mingo. They also thank the European Community for financial assistance within the Integrating Activity ‘Support of Public and Industrial Research Using Ion Beam Technology (SPIRIT)’, under EC contract no. 227012. E. Matykina also wishes to acknowledge the support from a Ramon y Cajal Fellowship (RYC-2010-06749).