Corrosion Challenges and Surface Protection Strategies for Magnesium Alloys
Magnesium alloys, with a density of approximately 1.74 g/cm³ (two-thirds that of aluminum and one-quarter that of steel), offer high specific strength and excellent damping capacity, making them attractive for automotive, aerospace, and consumer electronics applications. However, their standard electrode potential of −2.37 V versus the standard hydrogen electrode renders them highly susceptible to corrosion in humid atmospheres, chloride-containing media, and mild acidic conditions. This review systematically examines the corrosion mechanisms of magnesium alloys, categorizes corrosion types across different environments, and evaluates surface modification technologies including chemical conversion, electroplating and electroless plating, anodizing and micro-arc oxidation, laser surface treatment, thermal spraying, cold spraying, and organic coatings. These techniques form dense protective layers that isolate corrosive media and enhance corrosion resistance. Key findings from the literature demonstrate that laser surface melting with alternating magnetic fields reduces wear and corrosion rates, while laser-clad Al-Cu coatings on AZ91HP improve surface hardness and corrosion potential. Electroless nickel plating on AZ61 and anodizing treatments provide barrier protection, though coating adhesion and porosity remain challenges. The review also discusses current limitations such as long-term durability, cost-effectiveness, and scalability, and outlines future directions including multi-layer composite coatings and environmentally friendly processes. This work provides a reference for advancing magnesium alloy applications in engineering.