Recent advances in protective coatings and surface modifications for corrosion protection of Mg alloys

Magnesium (Mg) and its alloys possess many outstanding properties, showing great potential to be extensively applied in different fields. Unfortunately, they are highly susceptible to corrosion, especially to corrosive chloride ions. This causes huge economic loss and has restricted their applications in industry. Among different strategies, protective coatings/surface modifications attract considerable attention because they can reduce or even restrain corrosion by preventing contact with the external environment. This review focuses on the recent advances in various protective coating/surface modification technologies pertinent to Mg alloys to offer a clear picture for researchers and engineers in the relevant research area. The topics covered include anodic oxidation, plasma electrolytic oxidation, chemical conversion coating, sol-gel coating, laser cladding, cold spray, electrophoretic deposited coating, layered double hydroxide coating and superhydrophobic coating. In addition, the industrial applications of electrochemical (anodic oxidation and plasma electrolytic oxidation) and chemical conversion coatings are briefly presented. The existing issues and future perspectives are discussed to accelerate the broad applications of Mg alloys.