Study Of Corrosion Resistance About Magnesium Alloys And Its Micro-Arc Oxidation Coating In Simulation Body Fluid

Magnesium alloys is one of the most important biodegradable materials in 21th Century because of its similar density with bone and which is a necessary trace element for human body.Magnesium alloy has high strength and low modulus of elasticitys.The lively chemical properties of magnesium alloy make it easier to be corroded in application environment which limits the applycation of magnesium alloys.Micro-arc oxidation is a new type of surface modification method to improve the corrosion resistance of materials which can be grown in-situ ceramic oxidation layer on the surface.This paper mainly studies the corrosion resistance of magnesium alloy and its micro-arc oxidation coating in SBF solution,and at the same time explores the effect of hydrothermal treatment on micro-arc oxidation coating.The corrosion resistance of magnesium alloy and micro-arc oxidation coating were investigated by immersion test,polarization curve and electrochemical impedance spectroscopy.The composition,structure,morphology of magnesium alloy and micro-arc oxidation coating were characterized by energy dispersive spectrometer,X-ray diffraction and scanning electron microscope,respectively.The main contents are as follows:1.Compared the corrosion resistance and biocompatibility of several common commercial magnesium alloys such as ZK60,AM60,AZ91D and AZ31 in SBF solution. After soaking in SBF solution,Ca and P elements are deposited on magnesium alloy. AZ91D magnesium alloy has the best corrosion resistance.2.The formation of oxidation layer was studied by morphology,composition and corrosion resistance at various micro-arc oxidation times.There was hydroxyapatite deposition on the surface of the oxidation layer which is proved that the oxidation layer has the ability to induce the growth of bone.The oxidation layer has the best corrosion resistance when the oxidation time reaches 10min.3.Hydrothermal technique was used to handle the oxidation layer.The temperature and composition of hydrothermal solution were researched to improve the corrosion resistance and biocompatibility of oxidation layer.The corrosion resistance of oxidation layer was improved at higher hydrothermal temperature.The composition and concentration of hydrothermal solution also have a certain effect on the properties of the oxidation layer.