Enhanced corrosion resistance of AZ31 Mg alloy by one-step formation of PEO/Mg-Al LDH composite coating

In the present work, a novel one-step plasma electrolytic oxidation (PEO) method is developed for the formation of PEO/Mg-Al layered double hydroxide (LDH) composite coating on AZ31 Mg alloy. Through the control of electrolyte concentration, a Mg-Al LDH layer was formed on the surface of the resultant PEO coating. The corrosion properties of the composite coating were evaluated by electrochemical analysis, hydrogen evolution measurement and salt spraying testing, which exhibited improved corrosion resistance due to the presence of the Mg-Al LDH layer. This work provides a new strategy to take advantage of alloying elements in Mg alloys in PEO treatment to enhance corrosion resistance. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of Institute of Metal Research, Chinese Academy of Sciences. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )