Improvement in corrosion resistance of WE43 magnesium alloy by the electrophoretic formation of a ZnO surface coating
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A highly active Mg alloy, WE43, was electrophoretically coated by ZnO nanoparticles followed by heat treatment with the aim of decreasing its initial corrosion resistance for possible applications as biodegradable body implants. The investigation of the corrosion behavior of the coated WE43 surface was performed by electrochemical impedance spectroscopy in a phosphate-buffered saline solution (PBS). It was found that the highest corrosion protection resistance was achieved when the coating was formed at a cell voltage of 3 V during a 210 min deposition time. The corrosion protection efficiency of this coating was excellent, above 99.9% during a 6 h of immersion in PBS. The coating was found to be polycrystalline with a preferential growth direction along the c-axis, and the outer layer was composed of complex compounds containing oxides, carbonates, and hydroxides of Zn and Mg. The deposited ZnO nanoparticles were observed to be fused to an integral coating by heat treatment and thus provided excellent physical barrier against transport of corrosion species.
KeywordsWE43 magnesium alloy Electrophoretic deposition ZnO nanoparticles Corrosion Coatings
The authors would like to acknowledge the financial support from China Scholarship Council (201208420627), from State Key Laboratory of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology (Grant No. 2019-021), from the National Science and Engineering Research Council of Canada, and from Opening Project of Engineering Research Center of Nano-Geo Materials of Ministry of Education of China University of Geosciences (NGM2018KF015).
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