Factors affecting film thickness of ac anodized aluminium in sulphuric acid

Summary

The anodizing of commercial purity aluminium using alternating current and sulphuric acid electrolyte has been studied and film thicknesses measured at various applied currents and voltages. Using voltages below ∼50V to avoid burning, anodic film thicknesses up to 60μm have been obtained in 120min. Using oxidant anions of the ferric ion type, thicknesses up to 100μm could be obtained in 30 min. Evidence is given to show that ferric ion added as chloride gives the greatest effect and that some other common oxidants which are iron-free have little effect.

Additional information

Notes on contributors

J. A. Kneeshaw

Jonathan Kneeshaw is a graduate in Materials Engineering of the Loughborough University of Technology. He is now at the EEC Joint Research Centre in Petten, Netherlands, working in the field of high temperature corrosion of alloy steels.

D. R. Gabe

Dr David Gabe is a graduate of the Universities of Wales and Sheffield. His industrial experience includes tinplate research with the Steel Co of Wales and he is at present at Loughborough University of Technology where he directs the substantial research effort into metal finishing.