Preparation And Properties Of HA Coating Of AZ31 Magnesium Alloy Induced By Ti Ion Implantation Combined With PDA

Magnesium alloys are widely used in bone planting due to their low density,inherent biocompatibility and good mechanical properties.Magnesium alloy of the elastic modulus of about 40-45 gpa,and the human body bone elastic modulus（10 to40 gpa）is very close,as a result,it can minimize the current metal implants caused by the phenomenon of stress shielding.Magnesium is also one of the most important bivalent ions in the formation of bioapatite,which is an important element of bone metabolism.However,magnesium,as a kind of electronegative metal,corrodes faster than other metal materials,which limits its clinical application.Based on AZ31magnesium alloy as the research object,through titanium ion implantation pretreatment,combined with dopamine induced biomimetic mineralization law construction of hydroxyapatite coating on the corrosion of magnesium alloys in biomimetic mineralization process,further improve the corrosion resistance of AZ31magnesium alloy and cell compatibility.The main research contents and main research results are as follows:1.Preparation and characterization of Ti ion implanted pretreatment layer.Objective:to investigate the effect of different doses of titanium ion implantation on the corrosion resistance of AZ31 magnesium alloy and select the optimal ion implantation dose.Methods:AZ31 base material after grinding and polishing in vacuum target chamber,set leads to voltage is about 40 kv,the injection dose respectively set to 1 x10¹77 ions/cm²,2 x 10¹77 ions/cm²,3 x 10¹77 ions/cm²,4 x 10¹77 ions/cm²,5 x 10¹⁷ions/cm²,by XRD analysis into the change of crystal structure,XPS analysis layer surface components,rf pulse glow discharge spectrometry depth and elements of injecting into the relationship between the atomic percentage.The corrosion resistance of ion-implanted magnesium alloys was studied by the dynamic potential polarization curve.Results:AZ31 magnesium alloy was prepared by ion implantation technique.XRD results show that the surface crystal phase structure of titanium AZ31magnesium alloy has not changed.The glow results show that Ti element can be detected in all five samples,and the thickness of titanium injection layer is about 100-500nm.The dynamic potential polarization curve showed that when the injection dose was 3 x 10¹⁷ions/cm²,the corrosion resistance of ti AZ31 magnesium alloy was the most obvious.Combined with the above results,we will draw a voltage of 40KV and inject the ion implantation of 3 x 10¹⁷ions/cm² as the pretreatment of magnesium alloy.2.Titanium ion implantation pretreatment AZ31 magnesium alloy and graft dopamine-induced AZ31 magnesium alloy surface deposition hydroxyapatite coating.Objective:to improve the corrosion resistance and cell compatibility of AZ31magnesium alloys by using titanium ion implantation to pretreat AZ31 magnesium alloy and grafting dopamine to induce hydroxyapatite coating on the surface of AZ31magnesium alloy.Methods:titanium ion implantation AZ31 magnesium alloy surface by ion implantation,preprocessing of AZ31 magnesium alloy AZ31 magnesium alloy surface grafting dopamine in pretreatment after soaking in calcium phosphate solution biomimetic mineralization formation of hydroxyapatite coating.The surface morphology,element composition and crystal phase structure of AZ31 magnesium alloys were characterized by scanning electron microscopy and X-ray diffraction.The corrosion resistance of AZ31 magnesium alloy was studied by means of dynamic potential polarization curve and hydrogen analysis.The cell compatibility of modified magnesium alloys was investigated using Mc3t3-e1 cells.Results:titanium/dopamine/hydroxyapatite composite coating was successfully prepared on the surface of AZ31 magnesium alloy.When titanium ion implantation dose for 3 x 10¹77 ions/cm²,the petals point under the scanning electron microscopy（sem）composite coating surface can present sample structure,EDS results show that the composite coating calcium phosphorus ratio 1.65,a separate titanium ion implantation of coating layer and dopamine induced calcium phosphate coating is closer to hydroxyapatite 1.67 as a percentage of the theory of cross-sectional results show that the thickness of the composite coating,the thickest about 416.67 microns.The results show that the corrosion potential of the composite coating is the highest,which is-1210mvs.ag/AgCl,with the lowest corrosion current density,3.341x 10^-6.The results showed that the hydrogen precipitation of the composite layer was the most slowly.Determined by MTT experiment,according to the results of MC3T3E1 cells present dendritic structure,seedless mitotic figures,three groups of processing sample had no cytotoxicity and can promote cell proliferation,composite coating group 7 d cell increment rate is higher than other groups.The results of alizarin red staining showed that the calcium nodules in the composite coating group were darker and more numerous.AKP test results showed that the Alp activity was stronger than the control group.Conclusion:titanium ion implantation pretreatment of AZ31 magnesium alloy and grafted PDA,successful induction of AZ31 magnesium alloy surface forming hydroxyapatite composite coating,generate composite coating of magnesium alloy corrosion resistance and cellular compatibility were significantly enhanced.