| Titanium(Ti)has been widely used as the biomedical material,but its hardness is low,is easy to been scratched,and its corrosion resistance is also poor.Titanium nitride(TiN)coatings are expected to be used in the field of medical implants due to its high strength,appropriate elastic modulus,high corrosion resistance,and the ability to suppress the release of harmful metal ions from implants.However,the osseointegration ability of the TiN coating with the human bone is insufficient for biofixation,and its biocompatibility needs to be improved.The surface hydrothermal oxidation treatment of TiN coating can effectively enhance its osseointegration ability,nevertheless,as the implant material,other properties also need to be evaluated in profoundly.In view of this,this paper adopted multi-arc ion plating technology to prepare TiN coating on the surface of pure titanium substrate,and used the hydrothermal oxidation method to oxidize the TiN coating to study the effect of hydrothermal oxidation on the performance of TiN ceramic layer.Scanning electron microscope(SEM),energy dispersive spectroscopy(EDS),laser confocal microscope,X-ray diffractometer(XRD),X-ray photoelectron spectroscopy(XPS),nanoindenter,polarization curve,electrochemical AC impedance test(EIS),friction and multi function tribometer,etc.were used to characterize the physical and chemical properties,corrosion resistance,mechanical properties and friction wear properties of TiN coatings treated at different hydrothermal temperatures.The main research results and conclusions are as follows:Using multi-arc ion coating technology to prepare TiN coating on the surface of pure titanium substrate can significantly improve the hardness and elastic modulus of the substrate.The TiN coating has uniform texture and its thickness is about 2.43?m.When the hydrothermal oxidation temperature exceeds 150°C,anatase titanium dioxide(Ti O2)nanoparticles will be formed on the TiN surface,and a dense oxide layer will be formed when the temperature reaches 200°C.The oxide film can improve the wettability of the TiN coating,and the roughness of the coating also increased after the hydrothermal oxidation,thereby improving the biocompatibility of the TiN coating.After the hydrothermal oxidation treatment,the corrosion resistance of the TiN coating was improved.The higher hydrothermal temperature was,the better corrosion resistance was.Even with the presence of fluoride ions(F-),the corrosion resistance of TiN has been greatly improved.The immersion results showed that the Ti O2 layer on the hydrothermally treated TiN coating was intact after 5 weeks of immersion in the F-containing solution and provided good protection for the underlying TiN.Although the hydrothermal oxidation will slightly reduce the hardness of the TiN coating,it could still provide sufficient protection to the substrate.And the hydrothermal oxidation could reduce the friction coefficient of TiN coating,which had the effect of reducing wear.Studies showed that hydrothermal treatment at 200-250°C could comprehensively improve the properties of TiN coating necessary as biomedical materials. |
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