Preparation And Properies Y-Doped Microarc Oxidation Coating On AZ31 Magnesium Alloys

Background:The development,research and clinical application of biomedical implant materials are more and more widely used in various fields of medicine,especially in the field of organ tissue repair.Because of its good biomechanical properties,especially its elastic modulus,which is close to the elastic modulus of human bone tissue,and can be degraded in vivo,magnesium alloys have become the key research objects of implant materials.However,magnesium alloys are easily corroded in vivo,and the characteristics of rapid degradation also limit their clinical applications.So,the surface modification of magnesium alloys to improve their properties and ensure their biocompatibility has become the focus of current research.Research purposes:Yttrium-doped micro-arc oxidation coating was prepared on the surface of AZ31 magnesium alloy,and the surface morphology,hydrophilicity,coating adhesion,modified corrosion resistance and in vitro cytotoxicity of the coating were studied,providing new ideas for clinical application of AZ31 magnesium alloy.Materials and methods:In order to explore the modification effect of micro-arc oxidation on magnesium alloy and the change trend of modification effect with yttrium concentration,and to determine the optimum concentration of modification,this experiment is divided into six groups(AZ31,Y0,Y0.002,Y0.003,Y0.0035,Y0.004),using silicate electrolyte system,adding different concentrations of yttrium acetate((CH3COO)3Y)on magnesium alloys by Micro arc oxidation(MAO)to prepare yttrium-doped coatings,by scanning electron microscopy(SEM),X-ray diffractometer(XRD),energy dispersive spectroscopy(EDS),Fourier transform infrared spectroscopy(FT-IR),water contact angle Measuring instrument,scratch instrument,etc.to characterize the physical properties of the sample.The corrosion resistance of the samples was studied by hydrogen collection experiments,potentiodynamic polarization tests.Preliminary in vitro studies of sample biocompatibility were performed by cytotoxicity assay(CCK-8).Results:Micro-arc oxidation coatings with different yttrium-doped contents were successfully prepared on the surface of AZ31 magnesium alloy.With the increase of yttrium acetate concentration in the electrolyte,EDS showed that the yttrium content in the coating first increased and then decreased slightly.SEM showed that the pore size and apparent pores on the coating surface first decreased and then increased.When the yttrium acetate concentration was 0.0035mol/L,the pore size and porosity are the smallest;the peak of magnesium silicate in XRD is gradually significant,and the peak of Y₂O₃appears when the concentration of yttrium acetate is 0.0035mol/L;When the yttrium concentration is 0.0035mol/L,the film layer is the thickest;the scratch test shows that the coating has the strongest binding force when the yttrium concentration is 0.0035mol/L;the water contact angle is the smallest when the yttrium concentration is 0.0035mol/L,indicating that the hydrophilicity is the largest at this time;The corrosion resistance study shows that with the increase of yttrium acetate content,the polarization potential first increases and then decreases,indicating that the corrosion resistance first increases and then decreases.The corrosion resistance is the strongest when the yttrium concentration is 0.0035mol/L;CCK-8 test results show that with the addition of yttrium element,it will promote cell growth,indicating that the coating is basically non-cytotoxic,and the yttrium concentration of 0.0035mol/L significantly promotes cell growth.Conclusion:With the increase of yttrium acetate content,the corrosion resistance of AZ31 magnesium alloy yttrium-doped coating first enhanced and then weakened,and the cell compatibility was good.When the yttrium concentration was 0.0035mol/L,the surface morphology,hydrophilicity,coating adhesion,the modified corrosion resistance and cytotoxicity were better than other groups,which provided a new solution for the selection of implant materials and magnesium alloy modification.