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

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 (i(corr)) of coated Mg alloy and the flow rate (v) matches the linear relationship of i(corr)(-1) similar to v(-1/2), and the relationships between log(i(corr)) 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.