Anodizing of Mg alloys in alkaline solutions

The electrochemical behaviors of 99.95 mass% magnesium and its alloys, i.e. AZ31 and AZ91, were investigated in NaOH alkaline solution. Mg and Mg alloy specimens were anodized for 10 min at 3, 10 and 80 V in 1 mol/dm3 NaOH alkaline solution. The films anodized at 3 V on Mg and Mg alloys had the best effective corrosion resistance and these films consisted of comparatively thick magnesium hydroxide. Corrosion resistances of the films anodized at 80 V on Mg and Mg alloys were higher than those at 10 V and lower than those at 3 V, from results of the anodic polarization measurement in 0.1 mass% NaCl solution.