Electrochemical corrosion properties of CeO2-containing coatings on AZ31 magnesium alloys prepared by plasma electrolytic oxidation

[Display omitted] ► Plasma electrolytic oxidation of AZ31 Mg alloy was conducted in CeO2 particle-containing electrolyte. ► Corrosion properties of CeO2-containing PEO were evaluated by potentiodynamic and EIS tests. ► Corrosion resistance of AZ31 Mg alloy was significantly improved by CeO2 incorporation. ► CeO2-containing PEO coating was more protective against Cl− ion penetration during immersion test. Plasma electrolytic oxidation (PEO) of AZ31 Mg alloys was performed in CeO2 particle-containing Na2SiO3-based electrolytes, and electrochemical corrosion properties of CeO2-incorporated PEO coatings were investigated. The CeO2 particles were incorporated into the coatings at early stage and were preferentially located in the outer porous layer filling the defects such as pores. The potentiodynamic and electrochemical impedance spectroscopy tests in 3.5wt% NaCl solution indicated that the corrosion resistance of AZ31 Mg alloy was significantly improved by CeO2 incorporation. The high impedance of CeO2-containing PEO coated Mg alloy was still maintained after 40h immersion in 3.5wt% NaCl solution.