Corrosion Behavior of Micro-arc Oxidation-Coated AZ80 Magnesium Alloy in Simulated Body Fluid at Different Flow Rates

A self-sealing coating was prepared on the surface of basic magnesium alloy material (BM) by micro-arc oxidation (MAO) technique. The corrosion behavior of BM and MAO samples in a simulated body fluid (SBF) at different flow rates (0, 0.5, and 1.5 ml/s) was studied by immersion test. The electrochemical impedance spectrum (EIS) of the samples was measured at 0, 2, 12, 16 and 24 h during the immersion process to analyze the evolution of the electrochemical corrosion resistance. The corrosion morphology and element composition of the samples were characterized by scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The results showed that the corrosion resistance of BM and MAO samples gradually decreases with increasing flow rate. At higher flow rates, the MAO coating is more effective in improving the corrosion resistance of magnesium alloys. Based on the experimental results, the corrosion mechanism of BM and MAO samples at different flow rates was clarified.