Biocorrosion resistance of coated magnesium alloy by microarc oxidation in electrolyte containing zirconium and calcium salts

Abstract

The key to use magnesium alloys as suitable biodegradable implants is how to adjust their degradation rates. We report a strategy to prepare biocompatible ceramic coating with improved biocorrosion resistance property on AZ91D alloy by microarc oxidation (MAO) in a silicate--K₂ZrF₆ solution with and without Ca(H₂PO₄)₂ additives. The microstructure and biocorrosion of coatings were characterized by XRD and SEM, as well as electrochemical and immersion tests in simulated body fluid (SBF). The results show that the coatings are mainly composed of MgO, Mg₂SiO₄, m-ZrO₂ phases, further Ca containing compounds involve the coating by Ca(H₂PO₄)₂ addition in the silicate--K₂ZrF₆ solution. The corrosion resistance of coated AZ91D alloy is significantly improved compared with the bare one. After immersing in SBF for 28 d, the Si--Zr5--Ca0 coating indicates a best corrosion resistance performance.

Keywords

magnesium alloy / coating / microstructure / biocorrosion

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Acknowledgements

The partial supports from the National Natural Science Foundation of China (NSFC; Grant Nos. 51371071, 51321061 and 51275555), the National Basic Science Research Program (Grant No. 2012CB933900), the Fundamental Research Funds for the Central Universities (HIT.BRETIII.201202) and the Program for New Century Excellent Talents in University of China (NCET-08-0166) are gratefully acknowledged.

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg