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Volume 2018, Article ID 6268579, 9 pages
https://doi.org/10.1155/2018/6268579
Research Article

In Vitro Degradation Behaviors of Manganese-Calcium Phosphate Coatings on an Mg-Ca-Zn Alloy

1Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun 130025, China
2School of Engineering, RMIT University, Melbourne, VIC 3001, Australia

Correspondence should be addressed to Guangyu Li; nc.ude.ulj@uygnaug and Cuie Wen; ua.ude.timr@new.eiuc

Received 9 June 2017; Revised 8 October 2017; Accepted 31 October 2017; Published 13 February 2018

Academic Editor: Daniele Passeri

Copyright © 2018 Yichang Su et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In order to decrease the degradation rate of magnesium (Mg) alloys for the potential orthopedic applications, manganese-calcium phosphate coatings were prepared on an Mg-Ca-Zn alloy in calcium phosphating solutions with different addition of Mn2+. Influence of Mn content on degradation behaviors of phosphate coatings in the simulated body fluid was investigated to obtain the optimum coating. With the increasing Mn addition, the corrosion resistance of the manganese-calcium phosphate coatings was gradually improved. The optimum coating prepared in solution containing 0.05 mol/L Mn2+ had a uniform and compact microstructure and was composed of MnHPO4·3H2O, CaHPO4·2H2O, and Ca3(PO4)2. The electrochemical corrosion test in simulated body fluid revealed that polarization resistance of the optimum coating is 36273 Ωcm2, which is about 11 times higher than that of phosphate coating without Mn addition. The optimum coating also showed the most stable surface structure and lowest hydrogen release in the immersion test in simulated body fluid.