Preparation Of Mg-4.0Zn-0.4Sr Alloy Anodic Film And Phosphating Coating And They Degradation And Biocompatibility

With the development of biomedical materials,more and more materials were developed for medical devices.magnesium alloy because of its similar density with human bone,and essential trace elements?excellent mechanical properties?self-degradation?biocompatibility was concerned by reserchers.However,the rapid corrosion rate of magnesium alloys has hindered the development of magnesium alloys,and has been widely studied to improve the corrosion resistance of magnesium alloys.In this paper,on the basis of the self-designed alloy composition Mg-4.0Zn-0.4Sr,we prepared anodic oxidation coating on the surface of the alloy,and researched the effect of electrolyte,loading voltage and time on the corrosion resistance.The corrosion resistance and biological compatibility of phosphating is also studied,and evaluated materials corrosion resistant by vitro degradation test and cell proliferation rate and cytotoxicity test,obtained the following conclusions:1.The elastic modulus of Mg-4.0Zn-0.4Sr alloy is 39.4 MPa;yield strength is 85.98 MPa;the tensile strength of alloy 132.35 MPa,the mechanical properties in the range of mechanical properties of bone,bone can be used as material to reduce the stress shielding effection.2.Through the electrochemical workstation tests of coating corrosion resistance,we get several conclusions:Under same coating time,the corrosion potential of film increases with the increase of voltage,the most corrosion potential was-1.440 V and the smallest corrosion current density achieve was 8.4732×10-7 A/cm2 at 85 V.at the same time,it can be sure that the layer of adding glucose electrolyte was more compact and less porosity,the most corrosion potential was-1.2041 V,the smallest corrosion current density achieve was 5.59258×10-8 A/cm2.Corrosion potential positive shifted 370 mV,and corrosion current density reduced.So we can get that the best preparation technology of anodic oxidation coating was 85 V and 60 min and the corrosion resistance of the coating can be optimized by the addition of glucose.4.Phosphating sample morphology analysis,the phosphating coating surface is CaHPO4·H2O of column arrangement distribution and a little HA.The electrochemi-cal tests show that the corrosion potential of phosphating coating pattern was-1.306 V and corrosion current density was 3.12 E-7 A/cm2.Corrosion potential of uncoating specimens was-1.57 V and corrosion current density was 1.11 E-6 A/cm2,positive shifted 270 mV,the current density is reduced by one order of magnitude.Obviously the phosphating coat can effectively enhance the resistance of magnesium alloy corrosive.4.Through the test of cell proliferation rate and cell growth status,we get conclusions:compared with the control group,the cell proliferation rate followed by anodic oxidation coating>phosphating coating>uncoated magnesium alloy.Cell toxicity test showed that the cytotoxicity of the uncoated sample,the anodic oxide coating sample and the phosphate coating sample are less than 5%of the International Pharmacopoeia positive standard,In turn,anodic oxidation coating(2%)<phosphating coating(3%)<uncoated magnesium alloy(3.3%)<5%.Three kinds of samples showed good biocompatibility.All three samples showed good biocompatibility.