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

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 3.5.wt% 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 40 h immersion in 3.5 wt% NaCl solution. (C) 2012 Elsevier Ltd. All rights reserved.