Preparation And Characterization Of Microarc Oxidation/Aminated Hydroxyethyl Cellulose Coating On AZ31 Magnesium Alloy

In recent years,medical magnesium alloys have been widely studied for their excellent mechanical properties and biodegradability.However,magnesium alloys degrade easily.In addition,a large amount of hydrogen gas generated during the rapid degradation of medical magnesium alloys,which leads to the formation of emphysema and also cause the implant to loosen.All these factors limit the clinical application of medical magnesium alloys.Enhancing the corrosion resistance of magnesium alloys has become the focus of research.Research purpose:An AHEC+MAO composite coating was prepared on the surface of AZ31 magnesium alloy.The corrosion resistance and biocompatibility of the modified magnesium alloy were studied.Materials and methods:The samples were divided into three groups(AZ31 group,MAO+AZ31 group and AHEC+MAO+AZ31 group).Using the electrolyte with sodium hexametaphosphate as the main salt,MAO coating was prepared on the surface of AZ31 magnesium alloy.AHEC coating was prepared on the MAO layer by sol-gel spin method.The composition and surface morphology of the samples were characterized by Fourier infrared spectroscopy(FT-IR),Energy dispersive spectroscopy(EDS),X-ray diffractometer(XRD)and Scanning electron microscope(SEM).The corrosion resistance was studied through the Potential polarization test,the Hydrogen evolution experiment and the Long-term immersion experiment.The biocompatibility was studied in vitro through Cytotoxicity test(CCK-8)and Cell morphology observation.Results:The AHEC+MAO composite coating was successfully prepared on the surface of AZ31 magnesium alloy.SEM result showed that the composite coating had a uniform texture and was denser than the MAO coating.The pores and cracks were disappeared.The Potentiodynamic polarization test showed that the corrosion potential of composite coating was more positive with 450m V and the corrosion current density was reduced by 10~4times compared to the AZ31 Magnesium alloy.The high corrosion potential and low corrosion current density means low corrosion rate and high corrosion resistance.CCK-8 experiment and cell morphology observation experiment found that the cell proliferation rate of the experimental group was significantly better than that of the MAO+AZ31 group.This showed that with the addition of AHEC,the biocompatibility of the samples were improved.Conclusion:AHEC+MAO composite coating was successfully prepared on the surface of AZ31 magnesium alloy.The corrosion resistance and cell compatibility of the modified AZ31 magnesium alloy were better than those of simple micro-arc oxidation AZ31 magnesium alloy.This provides theoretical data support for the subsequent practical application of AZ31 magnesium alloy in clinical practice.