| Ti6A14V titanium alloy has become the preferred material for medical implants owing to its excellent comprehensive properties in corrosion resistance,wear resistance,biocompatibility,and mechanical properties.However,with the increase in service time,the corrosive action of human body fluids on Ti6A14V would make it release toxic metal ions such as Al3+,V2+,which may lead to adverse reactions of the host.Moreover,the weak wear resistance of Ti6A14V titanium alloy may cause aseptic loosening and even failure of the implant.In this paper,based on the problems existing in the clinical application of Ti6Al4V,the Ta2O5/Ta2O5-Ti/Ti composite coating was prepared on the surface of Ti6A14V by magnetron sputtering.The research on its design,preparation,residual thermal stress,microstructure,bonding strength,wear resistance,and corrosion behavior was carried out systematically.According to the gradient material theory,Ta2O5/Ti double coating,Ta2O5/Ta2O5-Ti/Ti composite coating,and Ta2O5-Ti gradient coating were designed on the surface of Ti6A14V titanium alloy.The residual thermal stress characteristics of the coatings were analyzed by ANSYS software,and the influence of the number and thickness of the intermediate layers and deposition temperature on the residual thermal stress of the coatings were investigated.The results showed that the maximum residual thermal stress of the coating decreased with the increase of the number of intermediate layers,but increased linearly with the increase of the deposition temperature.The maximum residual thermal stress of Ta2O5Ta2O5-Ti/Ti composite coating and Ta2O5-Ti gradient coating was decreased with the thickness of the intermediate layers.Ta2O5 monolayer coating,Ta2O5/Ti bilayer coating,and Ta2O5/Ta2O5-Ti/Ti composite coating(code ZD1,ZD2,ZD3)were prepared on the surface of Ti6Al4V by magnetron sputtering.The microstructure,bonding strength,mechanical properties,wear resistance,and corrosion resistance of the coating samples were investigated.The results showed that the Ta2O5 film exhibited an amorphous structure,and the chemical valence state of Ta was Ta5+.The order of surface roughness of coating samples from large to small is ZD 1>ZD2>ZD3.Ta,Ti,and O elements were distributed throughout the coating and diffuse to the substrate,indicating the visible element diffusion phenomenon.Ti and Ta2O5-Ti/Ti intermediate layer significantly improved the bonding strength of the Ta2O5 coating to the Ti6Al4V substrate.The bonding strength of the ZD3 samples was 299.4%and 171.4%higher than that of ZD1 and ZD2 samples.Compared with the ZD1 sample,the surface hardness,elastic modulus,and H3/E2 ratio of the ZD3 sample increased by 63.9%,66.5%,and 58.8%respectively.The three coatings improved the wear resistance of Ti6A14V titanium alloy,and the wear rate of ZD3 was 55.3%and 80.4%lower than that of the ZD1 and ZD2,respectively.All coatings improved the corrosion resistance of Ti6A14V titanium alloy.The coating sample with thicker Ta2O5 film showed better corrosion resistance,and the order of corrosion resistance of coating samples from high to low was ZD1>ZD2>ZD3. |
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