Biocorrosion behavior of micro-arc-oxidized AZ31 magnesium alloy in different simulated dynamic physiological environments

• Published in: Surface & coatings technology 2019-03, Vol.361, p.240-248
• Main Authors: Han, Linyuan, Li, Xuan, Xue, Feng, Chu, Chenglin, Bai, Jing
• Format: Article
• Language: English
• Subjects: Bacterial corrosion; Biocompatibility; Biocorrosion; Biomedical materials; Body fluids; Coating effects; Corrosion; Corrosion currents; Corrosion effects; Corrosion rate; Flow field; Flow velocity; In vitro methods and tests; Magnesium alloy; Magnesium alloys; Magnesium base alloys; Micro-arc oxidization; Polynomials; Protective coatings; Simulation; Surface coating; Surgical implants
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.01.052

The micro-arc-oxidization (MAO) technique was used to form the protective coating on the surface of AZ31 magnesium alloy and the corrosion performance of the coated magnesium alloy in static and different dynamic flow environments with three flow rates in simulated body fluid (SBF) were systematically studied in this paper. The results suggested that the protective effect of MAO coating was relatively weakened in simulated dynamic environments than that in static solution and the corrosion rate was accelerated when the flow rate arose. It is noticed that the corrosion current density (icorr) of coated Mg alloy and the flow rate (v) matches the linear relationship of icorr−1 ~ v-1/2, and the relationships between log(icorr) and corrosion time (t) at different v were polynomial fitted based on the electrochemical results. The calculated threshold of t when the coating and products layer lost their protective effects became earlier as the v increased. The influence of the flow field on the biocorrosion behavior of MAO coated magnesium alloy and the evolution of the protective effect of the coating during the corrosion process was also discussed. Our work provides a novel theoretical reference for studying the biocorrosion performance of coated magnesium alloys for future biomedical applications. •Dynamic physiological environment was simulated by self-designed biocorrosion test bench in vitro.•Influence of dynamic flow field on the protective effect of micro-arc-oxidized coating was reported.•Quantitative relationships between corrosion rates and flow velocities as well as corrosion time were determined.•Effect of flow environment on the corrosion mechanism and performance of coated Mg alloy was discussed.