A new look on the corrosion mechanism of magnesium: An EIS investigation at different pH

This study investigates the electrochemical impedance diagrams obtained for a Mg electrode in a sodium sul-phate solution at different pHs. A comprehensive model, independent of the pH range, with the presence of two adsorbed intermediates accounting for the anodic dissolution and the cathodic reaction was proposed to explain the singular behaviour of Mg at low pH values. It was also shown that, in acidic media, the contribution of the double layer as well as the cathodic partial reaction must be considered, whereas at higher pH values the oxide/ hydroxide layer plays a significant role and slows down the magnesium corrosion rate.

Automated summary

This study investigates the electrochemical impedance diagrams of a Mg electrode in a sodium sulfate solution at different pH values. A comprehensive model, independent of the pH range, is proposed to explain the singular behavior of Mg at low pH values, taking into account the presence of two adsorbed intermediates. The study also reveals that in acidic media, both the double layer and cathodic partial reaction should be considered, while at higher pH values, the oxide/hydroxide layer significantly slows down the magnesium corrosion rate.