The Influence Of Strontium-substituted Hydroxyapatite Coatings On The Corrosion Behavior And Cell Behavior Of Mg-4Zn Alloy

Magnesium(Mg)alloys for biomedical applications exhibit good biocompatiability,relatively low density and comparable mechanical properties as that of bone,so they are considered as promising implant materials.However,the high corrosion rate of the Mg alloys limits their clinical applications.The surface modification on these alloys with biochemical-stable and bioactive materials,e.g.Hydroxyapatite(HA)can significantly improve the corrosion propertites and biocompatiability of the Mg alloys as biomaterials.Besides,since strontium(Sr)can stimulate bone matrix formation,and inhibit bone resorption.The addition of Sr into the coatings can significantly improve the osseointegration of the Mg alloys.In this work,HA coatings with different Sr content were deposited on the Mg-4Zn alloy using electrochemical deposition.Fourier Transform Infrared Spectroscopy(FTIR),X-ray Diffraction(XRD),Field Emission Scanning Electron Microscope(FESEM)and Energy-Dispersive X-ray Spectrometer(EDS)techniques were applied for the crystal structure,phase constitution,characterization of surface morphology and chemical composition.The corrosion properties of the samples were measured by immersion corrosion and electrochemical polarization curves.The biocompatibility of samples was analyzed by cell adhesion,cell proliferation and differentiation.The results demonstrated that the Sr-substituted HA coatings showed finer microstructure,better corrosion resistance and improved biocompatibility with increasing Sr:(Ca+Sr)atomic ratio.