Preparation and microstructure of MAO/CS composite coatings on Mg alloy

[Display omitted] •The composite coating is formed on Mg alloy by a microarc oxidation and chitosan.•The composite coating improved the corrosion resistance of MAO coating.•The dipping times effects on the properties of MAO coatings. Micro-arc oxidation (MAO)/chitosan (CS) composite coatings were fabricated via MAO processing and subsequent sealing with CS solution at different dipping times. The effect of dipping times on the surface morphologies, chemical compositions and corrosion resistance of the coatings was investigated in this study. The results indicated that the MAO coating was efficiently sealed by the CS film. The potentiodynamic polarization tests show that the MAO/CS coatings enhanced the corrosion resistance of the MAO coating. The corrosion resistance of MAO coating dipping in chitosan solution for three times was improved significantly compared to other composite coatings due to its fewer microcracks and greater thickness.