The influence of surface treatment on the anodizing of magnesium in alkaline solution

The mechanism of magnesium anodizing after mechanical polishing or HF pickling was studied. X-ray Photoelectron Spectroscopy and Photocurrent Spectroscopy were employed to characterize both the initial films formed on Mg soon after surface treatments and the anodic films grown in strongly alkaline solutions. Electrochemical and capacitance measurements were performed in order to study the oxidation process and to check if the kinetic of growth fits the Mott–Cabrera high field model. From Tafel plots it was possible to estimate the activation distance, while the simulation of the barrier layer growth as a function of the potential at high scan rate allowed to estimate the other kinetic parameters of Mott–Cabrera model. An influence of the initial layer composition on such parameters was evidenced.