B. Mingo

Recent advances in energy efficient PEO processing of aluminium alloys

Abstract Plasma electrolytic oxidation (PEO) coatings developed under voltage-controlled mode on various commercial wrought, gravity cast and rheocast aluminium alloys were discussed with respect to enhancement of their tribological and corrosion performance and minimization of the PEO energy consumption. It is demonstrated that use of conventional porous anodic film precursors reduces the PEO energy consumption by up to 50%. The wear of 6082 alloy with PEO coatings with added α-Al2O3 particles is two times lower compared with electrolytic hard chrome. The long-term corrosion resistance of the PEO-coated A356 rheocast alloy is enhanced via use of a precursor and hydrophobic post-treatment.

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.