Composite coatings on a Mg–Li alloy prepared by combined plasma electrolytic oxidation and sol–gel techniques

We present a facile procedure by combining plasma electrolytic oxidation (PEO) technique with sol–gel method to improve the corrosion resistance of magnesium–lithium alloy. A further deposition of a titanium sol–gel layer on the PEO film improves the compactness and anti-corrosion properties. X-ray photoelectron spectroscopy and X-ray diffraction measurements reveal that the PEO coating is composed of MgO and Mg2SiO4, while after sol–gel treatment, the coating contains titania and some low valence titanium compounds. Long-term immersion testing show that the PEO/sol–gel composite coating with better compactness and fewer defects exhibits a superior anti-corrosion property in comparison with PEO alone.

► We fabricate PEO/sol–gel composite coatings on Mg–Li alloy.
► We examine the properties of PEO and PEO/sol–gel coatings.
► The composite coatings can effectively suppress the corrosion of Mg–Li alloy.