Effect of Plasma Electrolytic Oxidation Process on Corrosion Resistance of Al-Coated AZ61 Magnesium Alloy

Magnesium alloys are extensively utilized in aerospace, aviation, and automotive sectors due to their low density and high specific strength, which offer significant advantages for lightweight structural applications. Their low density especially directs the attention of the aviation sector, where lightness is necessary, to these alloys. However, one of the disadvantages that restricts their use in the industry is their low corrosion resistance. In this study, the Plasma Electrolytic Oxidation (PEO) process was applied in a silicate-based electrolyte to AZ61 magnesium alloy pre-coated with aluminum using the electric arc spraying technique. To examine the characteristics of the fabricated coatings, their phase structures, surface features, and elemental compositions were investigated through XRD, SEM, and EDS analyses. Corrosion performances of coatings were investigated by potentiodynamic polarization test in 3.5% NaCl solution. As a result of electrochemical tests, corrosion current density values for the base sample (AZ61) and PEO coating (AZ61-PEO) were determined as 36,29 μA. cm−2 and 6,53 μA. cm−2, respectively. The findings highlight that the Al₂O₃ layer formed following PEO treatment significantly enhanced the corrosion resistance compared to the base sample.