| Biocompatibility is one of the most considerable problems in the study of Ti matrix biomedical material. In order to improve titanium alloy's biocompatibility, the titanium dioxide coating was fabricated on Ti matrix. Besides, the surface of titanium alloys was directly disposed by alkali to make it possess bioactivity. Biocompatibility and bioactivity of the material after surface modification were evaluated through the simulated body fluid (SBF) cultivation and cell cultivation experiment. Surface morphology, phase constitution and biocompatibility of the material were analyzed and evaluated in this paper.Titanium alloys were prepared by non-consumable vacuum arc smelting furnace. And the microstructures and the properties of titanium alloys were investigated. The structure character of cast titanium alloys was studied. The alloy elements selected in this experiment were Mo, Nb, Zr and Fe, which were β stable elements.The excellent resist erosion and biocompatibility of pure titanium and titanium alloys are attributed to the TiO2 film on the surface. So the titanium dioxide coatings were fabricated by cladding substrates to sinter in different work mediums, which included normal pressure and vacuum conditions. The surface morphology and phase constitution of coatings were analyzed. The results indicated that the crystal particles in coatings were mostly rutile, and the size of the rutile was in a micrometer grade. The surface roughness of coatings was different.Surface roughness of coatings affects the bioacitivity of materials, In order to change the roughness of coatings, the granularity of coating powders was changed firstly. Nanometeral anatase titanium dioxide powders were prepared by hydrolysis of titanium-tetrabutoxide with ethanol in this paper. The main particle size is between 5nm and 10nm, while the size of ordinary titanium dioxide powders is about 100nm. The nanoparticles coating was fabricated by cladding titanium alloys with nano-TiO2 powders, and its surface roughness was 2.1-2.3 μ m which was smaller than that of ordinary titanium dioxide coatings. The diameter of crystal particle in nano-coatings is mainly between 50nm and 100nm, and sometimes less than 50nm.In addition to fabricate coatings on the surface of titanium alloys, the bioactivities on thesurface of titanium alloy substrates were done by alkali solution. Making use of statistical principle, the different Ti substrates were dealt with in different temperatures(60℃~100℃) by different concentrations(5M~10 M) NaOH solutions so that we can confirm the most appropriate technique.Biocompatibility and bioactivity of the material after surface modification were evaluated through the simulated body fluid cultivation experiment. After cultivated for same days, the capability of Ca phosphates deposition of nano-TiO2/Ti alloys was the best. The SBF cultivation results by different surface modification methods were: nano-TiO2 coating > alkali solution treatment > TiO2 coatings sintered in normal pressure > TiO2 coatings sintered in vacuum.The nano-TiO2/Ti alloys possessed favorable cell compatibility testified by the cell cultivation experiment.
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