Advancements in enhancing corrosion protection of Mg alloys: A comprehensive review on the synergistic effects of combining inhibitors with PEO coating

Magnesium (Mg) alloys are lightweight materials with excellent mechanical properties, making them attractive for various applications, including aerospace, automotive, and biomedical industries. However, the practical application of Mg alloys is limited due to their high susceptibility to corrosion. Plasma electrolytic oxidation (PEO), or micro-arc oxidation (MAO), is a coating method that boosts Mg alloys’ corrosion resistance. However, despite the benefits of PEO coatings, they can still exhibit certain limitations, such as failing to maintain long-term protection as a result of their inherent porosity. To address these challenges, researchers have suggested the use of inhibitors in combination with PEO coatings on Mg alloys. Inhibitors are chemical compounds that can be incorporated into the coating or applied as a post-treatment to further boost the corrosion resistance of the PEO-coated Mg alloys. Corrosion inhibitors, whether organic or inorganic, can act by forming a protective barrier, hindering the corrosion process, or modifying the surface properties to reduce susceptibility to corrosion. Containers can be made of various materials, including polyelectrolyte shells, layered double hydroxides, polymer shells, and mesoporous inorganic materials. Encapsulating corrosion inhibitors in containers fully compatible with the coating matrix and substrate is a promising approach for their incorporation. Laboratory studies of the combination of inhibitors with PEO coatings on Mg alloys have shown promising results, demonstrating significant corrosion mitigation, extending the service life of Mg alloy components in aggressive environments, and providing self-healing properties. In general, this review presents available information on the incorporation of inhibitors with PEO coatings, which can lead to improved performance of Mg alloy components in demanding environments.