In Situ Preparation Of Bio-functional Films On Titanium Materials By Hydrothermal Method

Titanium based alloys have many advantages as implant materials, such as low density, high strength, low elastic modulus, excellent Bio compatibility and so on. However, it has poor ability of interfacial bonding with human tissue, which lead to infection easily when implanted into the human body, so that its application is subject to many restrictions. Surface modification is beneficial to improve osseointegration properties and antimicrobial properties of titanium material and expand its application.. In many modification methods, hydrothermal method has the advantages of simple process and low cost and can be used to implant with complex shapes. In this paper, We study the process and mechanism about situ preparation of bio-functional films on titanium materials by hydrothermal method.Firstly, the process about hydrothermal synthesis of hydroxyapatite coating on TLM(Ti-25Nb-3Zr-2Sn-3M) was studied. Heated at 200℃ for 16 h in 3.3mmol/L Ca3(PO4)2, 10mmol/L CaHPO4 and 10mmol/L Ca(H2PO4)2 solution as the hydrothermal medium respectively. Three kinds of samples all synthesized anatase, only CaHPO4 and Ca(H2PO4)2 generated Hydroxyapatite nanoparticles, Hydroxyapatite nanoparticles in CaHPO4 was the most intensive; SEM and EDS showed that nano-particles in the film was Ca and P elements and XPS confirmed the Ca and P was combined with hydroxyapatite. After soaking test in the simulated body fluid for 15 days, Hydroxyapatite was detected for the sample hydrothermally treated in CaHPO4 solution. Which shows the biological activity of TLM. The electrochemical testing also showed that the corrosion current density of TLM was decreased from 7.75nA/cm2 to 7.35nA/cm2, and the corrosion resistance of TLM was enhanced.Secondly, the method and the properties about the hydrothermal synthesis of silver-containing titanium dioxide film on TLM alloy was studied. TLM samples was heated at 200℃ for 12 h, 24 h respectively in 10mmol/L silver nitrate as hydrothermal medium. Silver-containing anatase film were formed on the TLM; Titanium and niobium transformed for TiO2 and Nb2O5, silver existed in the form of metal state; After sample was irradiated 30 min under a 253 nm wavelength of ultraviolet light, its water contact angle reduced from 108° to 10°. The result indicated that the film had a good photo-induced hydrophilicity; After cultured 24 h in the medium with E. coli and Staphylococcus aureus, samples appeared significant inhibition zones, especially Staphylococcus aureus inhibition zone was wider, which showed better antibacterial properties for Staphylococcus aureus.Finally, it was studied of that the sol-gel-hydrothermal method for preparation of nanostructured hydroxyapatite coating on titanium surface. Twice gel film was prepared on the substrate by dip-coating method with prefabricated bioactive glass sol, after was calcined and appeared bioglass film; The specimen was heated at 200℃ for 12 h in 10mmol/L CaHPO4 as reaction medium. SEM showed the samples surface formed nanorods and nano-sheet structure. EDS showed that the film mainly containing Ca and P, and XPS showed that Ca and P elements combined with hydroxyapatite, however, XRD detected the hydroxyapatite diffraction peaks. Electrochemical tests show that the hydroxyapatite coatings prepared by sol-gel-hydrothermal hydrothermal improve the corrosion resistance of titanium substrate.