Effects of flow velocity and different corrosion media on the in vitro bio-corrosion behaviors of AZ31 magnesium alloy

The bio-corrosion behaviors of AZ31B magnesium alloy under the dynamic conditions with different flow velocities and immersion media including normal saline (NS), phosphate buffered solution (PBS), and simulated body fluid (SBF) are studied in this work. The results indicated that the corrosion of the magnesium alloy was accelerated in three solutions as the increase of flow velocity. The flow-induced bio-corrosion tended to be uniform in PBS and SBF while the localized corrosion became more serious in NS compared with static conditions. During the predetermined 48 h, the relationships of corrosion rates of AZ31B in three media are NS > SBF > PBS for the first 10 h, and then turned to NS > PBS > SBF after 12 h. The corrosion current density (icorr) of magnesium alloys and the flow velocity (v) matched a relationship of icorr−1 ∼ v−1/2 well at first but started to deviate at 1 h, 4 h, and 8 h in NS, PBS, and SBF respectively. The influence of flow velocity and corrosion medium on the flow-induced bio-corrosion behavior of magnesium alloy was systematically discussed as well, which will provide a theoretical reference for the future practical applications of biomedical Mg alloy.