Improved wear and corrosion resistance of MoS2/MgO/MgAl2O4 composite layer in-situ prepared by one-step micro-arc oxidation

In this study, a MoS2/MgO/MgAl2O4 composite layer was prepared on AZ31 magnesium alloy via a one-step insitu plasma electrolytic oxidation (PEO) method to enhance its wear and corrosion resistance. Results indicated that the addition of Na2MoO4 and Na2S significantly increased the critical and final voltages during the PEO process, and gradually reduced the layer porosity. When 2.5 g/L Na2MoO4 and 5 g/L Na2S were added, the layer exhibited optimal wear resistance, with an average coefficient of friction (COF) of 0.1521+0.007 and a wear volume of 0.0193+0.001 mm3. Additionally, when 1.5 g/L Na2MoO4 and 3 g/L Na2S were added, the layer exhibited optimal corrosion resistance, with a corrosion current density of 1.466x10- 9 A/cm2 and a corrosion potential of -0.351 V. Compared to the AZ31 substrate and the single PEO layer, the corrosion current density improved by 4 and 2 orders of magnitude, respectively, and the corrosion potential shifted positively by 0.968 V and 0.182 V, respectively. Elemental analysis showed that S and Mo were primarily distributed at the interface between the layer and the substrate, with their concentration decreasing from the inner to the outer layers of the layer, indicating their involvement in the layer formation process. MoS2 was mainly distributed within the interior of the layer.