Investigation of wear, corrosion and tribocorrosion properties of AZ91 Mg alloy coated by micro arc oxidation process in the different electrolyte solutions

Micro arc oxidation (MAO) is an effective technique to improve the surface properties of light materials by forming ceramic films on the surface. A number of studies have been carried out regarding depositing on Mg and Mg alloys. However, only a few have focused on wear, corrosion or tribocorrosion properties. In this study, the MAO process was carried out on AZ91 Mg alloy in two different electrolyte solutions; namely phosphate–silicate and potassium stannate. The microstructures, morphology and crystallographic structure were analysed using SEM and XRD. The wear, corrosion and tribocorrosion properties of the coatings were investigated using the pin-on-disc wear test, potentiodynamic polarisation test and combining the tribocorrosion test unit, respectively. The results showed that the type of solution has an important role on the wear, corrosion and tribocorrosion resistance of the MAO coating.

► AZ91 Mg Alloys were coated by Micro Arc Oxidation process.
► Two different solutions were used as an electrolyte.
► MAO coating modified the wear, corrosion and tribocorrosion properties of AZ91.