Magnesium (Mg) alloys are potential lightweight structural materials for automotive, aerospace, electronics, and biomedical applications. However, their commercial application is restricted due to their low aqueous corrosion resistance owing to the formation of a less protective surface oxide layer with an exterior porous hydroxide layer. Optimized plasma electrolytic oxidation (PEO) has been successfully used to apply protective surface coatings with improved coating thickness, adhesion, mechanical properties and corrosion resistance. PEO is an electrochemical conversion approach that primarily relies on the local plasma discharges at the metal/electrolyte interface at high voltages. Plasma is generated by the electric breakdown under anodic polarization, where the substrate is converted to a compound comprised of oxygen and component elements of the substrate/electrolyte. The intense interim discharges lead to surface melting and the

reformation of the oxide layer. Research conducted by IRC-AM members led by Dr. Saji Viswanathan has achieved superior PEO coatings by combined in-situ incorporation of hexagonal boron nitride (BN) nanosheets, organo-modified nanoclays (NC) and stannate (ST) corrosion inhibitor into the PEO layer.  Their study discloses that hard nanoparticles with a high melting point, such as BN, could be more effectively incorporated into the PEO layer with the co-deposition of low-melting NC. Nanoclays help in liquid phase sintering and developing a more homogenous and thicker PEO layer with improved bonding strength, whereas BN nanosheets enhance mechanical properties and corrosion resistance. The study also found that simultaneous incorporation of an inhibitor such as ST can make an effective protective conversion layer, providing an additional protective effect without significantly interfering with the PEO layer formation. This method of fabrication of PEO coatings with improved characteristics could be used for applications of lightweight materials.