Influence of plasma electrolytic oxidation coatings on fatigue performance of AZ31 Mg alloy


Magnesium and its alloys are attractive for lightweight construction, but suffer often from poor corrosion resistance. Plasma electrolytic oxidation is a promising surface treatment to overcome these limitations. Recently, introduction of particles to the PEO electrolyte has been explored as new strategy to provide a wider range of compositions and new functionalities for PEO coatings. However, this surface treatment can have negative impact on the fatigue strength. In the present study, the influence of PEO coatings with and without particle addition on the corrosion fatigue behavior of AZ31 Mg alloy is investigated. The corrosion fatigue behavior is investigated in load increase tests and constant amplitude tests in 0.5% NaCl solutions. Results are correlated with the corrosion behavior evaluated in polarization and electrochemical impedance spectroscopy measurements. Corrosion tests show significant improvement of the corrosion resistances of PEO-coated specimens. However, the uncoated material exhibits the highest corrosion fatigue strength, whereas a reduction of 7% for the PEO-coated specimen without particles and 27% for the PEO-coated specimen with particles is found.
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