Study On Fabrication And Properties Of Mg-Based Amorphous Alloy And Its Hydroxyapatite Coatings

As the most promising temporary medical implant material at present,magnesium alloy has many advantages such as biodegradability and mechanical properties similar to human bone,but its degradation rate in vivo is too fast,and H₂precipitation in the degradation process and other problems limit its clinical application.Amorphous magnesium alloy has high strength and excellent corrosion resistance due to its special structure,and Mg-Zn-Ca based amorphous alloy has broad application prospect as a biological material because its elements are degradable and its biocompatibility is good.Since the Mg-Zn-Ca critical dimension of amorphous alloy is limited,the degradation speed still can not meet the clinical needs.As a common element of grain refinement of magnesium alloy,Nd element has good biocompatibility.Therefore,trace Nd elements were added to Mg-Zn-Ca amorphous alloy.Firstly,Mg-Zn-Ca base amorphous alloy was prepared by copper injection casting,and then XRD,DSC and SEM were used to analyze the properties of the material,through electrochemical test and simulate fluid immersion test,study Nd elements for Mg-Zn-Ca amorphous alloy amorphous formation ability and corrosion resistance.The results show that the addition of Nd can reduce the amorphous forming ability of Mg-Zn-Ca amorphous alloy and improve the corrosion resistance of Mg-Zn-Ca amorphous alloy.Since the addition of Nd element will reduce the glass forming ability of Mg-Zn-Ca alloy,it is considered to increase the corrosion resistance of Mg-Zn-Ca alloy by means of surface modification.As we all known,hydroxyapatite coating has excellent biological activity and excellent corrosion resistance.Hydroxyapatite coating was prepared on the surface of Mg-Zn-Ca amorphous alloy by hydrothermal method in this paper,and the optimal process scheme for the preparation of HA coating by hydrothermal method was determined.The phase composition and structure of the coating were analyzed by XRD,SEM and EDS.The outer coating is rough Ca/P compound with a certain porosity,the middle layer is acicular nano hydroxyapatite,and the inner layer is ZnO and some Ca/P compounds.Corrosion test results show that the corrosion resistance of the amorphous alloy with HA/ZnO coating is better than that without coating.In vitro antibacterial experiments showed that the coating had excellent antibacterial properties.