| Sandblasted,large-grit,acid etched(SLA) and anodic-oxidation was used toconstructing hierarchical micro-nano porous topography on titanium surface. Then thebioactivity of the coatings were improved by the thermal treatment and hydrothermaltreatment. The microstructures, chemical and physical properties of titanium surfacewith different methods treated were studied by the scanning electronicmicroscope(SEM),confocal laser scanning microscopy(CLSM),x-ray diffraction(XRD)，x-ray photoelectronic spectroscopy(XPS),contact angle analizer, BET surface areameasurement and electrochemical workstation. After soaking in the SBF, the coatingswith different method treatment was investigated by SEM,EDS,XRD and Fouriertransform-Infrared spectra (FT-IR) to evaluated their bioactivity in vitro.The sandblasted improved the roughness of titanium surface with the maincomposition of it unchanged. Then, the specimens after sandblasted,large-grittreatment(SAN) were soaked in the49%wt sulfuric acid for1h at60°C to form themicro-porous topography of titanium surface. The average roughness of SAN wasfurther improved after SLA treatment. And the roughness values of them are all higherthan the specimen only through acid etched(ACT).The anodic-oxidation was used to create nano-structures based on the micro poroustitanium surface. The effect of the processing time, electrolyte concentration and voltageon the nanotubes forming were investigated in this research. Then the paper choose themost applicable parameters of anodic-oxidation to form the ideal micro-nano porousstructure on titanium surface. The progress is conducted at20V for1h in a glycerolelectrolyte containing50%H2O and10g/L NH4F. The nanotubes mainly consist ofamorphous titanium dioxide.X-ray photoelectronic spectroscopy(XPS) patterns of theANO sample shows that there are two different states of Ti which areTi2+corresponding to TiO and Ti4+corresponding to TiO2in the amorphous titaniumdioxide. The average roughness of ANO samples is lower than that of SLA samples,however, the surface area of the former is larger than that of the latter. Moreover, thenitrogen adsorption-desorption techniques indicates that the pore diameter of thecoatings on ANO samples is about20and500.The thermal treatment (THER)did not change the morphology of ANO samples when making the amorphous titanium dioxide crystallize into anatase. Then, the hydrothermaltreatment(HYDR) after thermal treatment turned the nanotubes into randomly arrangednanosticks with the mainly compositions of it remaining The EDS and XPS patternsshows that the HYDR samples mainly contain Ti,O and minute quantity of Ca and Pelements.Before the anodic-oxidation, the hydrophily and roughness of samples have the sametendency of changes with respect to treating processes, that is, the much higher theroughness value is, the smaller the contact angle is. Whereas, after anodic-oxidation, thenanostructure forming on the micro porous titanium surface improved the hydrophily ofit dramatically perhaps because it increased the surface area of samples significantly.Besides, the corrosion resistance of anatase is superior to that of amorphous titaniumdioxide.Four types of specimens were immersed in SBF to evaluated their bioactivity in vitro.SEM and XRD patterns indicates that SLA and ANO samples have no apatite formationability. After3days immersing, a few apatite spheres appeared on THER and after14days immersing, the apatite coatings cover all the surface of THER. Only through3days immersing, HYDR were covered with a film of apatite. According to FT-IRspectrogram, the induced apatite by all types of coatings contain Therefore, the apatiteformation ability of HYDR excels the other kinds of coatings. To conclude, themicro-nano porous coatings has much higher roughness, larger surface area and betterhydrophily than untreated titanium surface. With modification of thermal andhydrothermal treatment, the coatings maintain those character above-mentioned andhave superior bioactivity. |
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