| In recent years,?-titanium alloy has become an important research dirction of biomedical materials due to its good biocompatibility,high specific strength and low elastic modulus.But the medical titanium as a bio-inert material,it can not be fast to achieve bony bonding between the ?-titanium alloy and the new bone tissue.At the same time,its long-term use in the human body environment still has the possibility of corrosion of the surface.Therefore,the surface modification of the ?-titanium alloy is current an important methods for improving the performance of materials biomedical and the performance of long-term servicet.In order to further improve the coating adhesion and the corrosion resistance,this thesis mainly studies the preparation of the?-titanium alloy nanocrystalline,and the effect of nano-crystalline structure on the preparation of surface micro-arc oxidation coating,coating biological activity and corrosion resistance,and lays a theoretical reference for the clinical application of ?titanium alloy.Micro-arc oxidation(MAO)is a kind of easy operation and obvious effects of titanium alloy surface treatment technology,the porous coating can enhance bone induction and thus improve the biological inertia of ?-titanium alloy,but the single MAO coating has the disadvantages of high porosity and low interfacial bonding strength.Actually,the matrix organizational structure affect the quality of the Micro-arc oxidation coating.Therefore,the surface of Ti3Zr2Sn3Mo25Nb(TLM)titanium alloy was nano-treated by sliding friction treatment(SFT)to study the effect of grain refinement on the physical and chemical properties and biological properties of the coating,which can provide a new idea for the surface modification technology of titanium alloy and the development of device.The 100?m-thick deformed layer was successfully prepared on the surface of a?-titanium alloy with a small amount of ?-phase by SFT technology,and the surface grain size was refined to nanocrystalline(NC),and the surface layer was a single?-phase.Electrochemical corrosion test results show that sliding friction technique can improve the corrosion resistance of TLM titanium alloy.The surface microstructure and chemical composition of the NC-MAO coating prepared by the combination of sliding friction treatment and micro-arc oxidation technology are not significantly different from the CG-MAO coating that prepared on the original coarse crystal TLM matrix,but the fine-grained microstructure reduces the pore density of the NC-MAO coating and improves the surface hydrophilicity of the coating.The results of electrochemical test and immersion experiment show that the nanocrystalline micro-arc oxidation coating has better corrosion resistance than the coarse crystal micro-arc oxidation coating,indicating that the sliding friction pretreatment technology can improve the quality of the coating and enhance the corrosion protection effect on the substrate.The biomedical performance evaluation of the coarse crystal micro-arc oxidation coating and the nanocrystalline micro-arc oxidation coating samples were studied by cell adhension,Cell morphology,cell proliferation and protein adhesion tests.The cell adhesion results showed that the nanocrystalline micro-arc oxidation coating samples has better biological activity.The results of cell morphology and proliferation test indicated that nanocrystalline micro-arc oxidation coating could better promote differentiation of MC3T3-E1 osteoblasts than those of coarse crystal micro-arc oxidation coating samples.In addition,the results of protein test showed that nanocrystalline micro-arc oxidation coating has better protein adsorption ability and was beneficial to cell adhesion.The improvement of biocompatibility of nanocrystalline micro-arc oxidation coating samples is mainly attributed to the excellent nanoscale structure and stable corrosion micro-environment of the coating. |
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