Enhanced corrosion protection of MgO coatings on magnesium alloy deposited by an anodic electrodeposition process

MgO coatings were prepared on magnesium alloy surface by an anodic electrodeposition process in concentrated KOH solution followed by heat treatment in air. The phase composition and microstructure of the as-formed MgO coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behavior of the MgO-coated samples was evaluated by electrochemical measurements and immersion tests in Hanks’ solution. The results showed that the MgO-coated Mg alloy exhibited a much superior stability and lower corrosion rate, and thus enabled to improve the corrosion resistance, whereas the bare Mg alloy suffered from severely localized corrosion attack.

Research highlights► Dense MgO coatings with a thickness of 25 μm on magnesium alloy substrate are produced by an anodic electrodeposition process in KOH alkaline solution and subsequent thermal treatment ► Both electrochemical measurements and immersion tests in Hanks’ solution show that MgO coatings could suppress the corrosion process by preventing the corrosive ions from transferring or diffusing to the magnesium alloy substrate, and thus improve the corrosion resistance ► The anodic electrodeposition process might be an alternative method to PEO to produce layers that could provide better corrosion protection to magnesium alloys