Stress corrosion crack propagation behaviour of MAO ceramic coating on Mg alloy

This study investigates the impact of static tensile loads on magnesium (Mg) alloys with and without ceramic coatings in simulated body fluids (SBF) using a combination of numerical simulation and experimental methods. The surface of an AZ31B Mg alloy was treated with a ceramic coating via micro-arc oxidation (MAO). Subsequently, bare Mg-alloy and MAO ceramic-coated specimens were subjected to static tensile stress testing using a tensiometer. After immersion for 12 h in SBF, the surface morphology and electrochemical corrosion of the stressed specimens were analysed. Notably, under the same tensile stress, the Mg alloy in the SBF exhibited more severe corrosion damage than the ceramic-coated specimen. Furthermore, there was a direct correlation between the corrosion rate of the ceramic coating and the magnitude of the applied tensile stress. Overall, the MAO ceramic coating exhibited superior corrosion resistance compared to the bare Mg alloy, even after undergoing static tensile stresses. The study demonstrates that MAO ceramic coatings can enhance the corrosion resistance of biodegradable Mg implants by protecting them from the combined effects of bodily stresses and fluids.