Papers by Keyword: Titanium Oxide

Abstract: The corrosion behavior of pre-treated Fe–Al alloy in a sulfuric acid solution and chloride-containing solution was studied. Alumina layer formed at 1073–1173 K on the surface of Fe–Al alloy improves the corrosion resistance of the alloy, whereas that at 1273 K does not improve it. This was explained by the defects of Al2O3 layer, the fraction of Al2O3 in the oxides, crystallity of Al2O3, and residual stress in the oxide layer. On the other hand, TiO2 layer produced by dip coating and subsequent annealing at 523–773 K slightly improved the corrosion resistance of the alloy. The effect of the oxide layer on the aqueous corrosion was discussed focusing on the quality of the oxide.

Abstract: The bioactivities of titanium oxide film on titanium surface received from different chemical treatment methods were studied in SBF in vitro and mechanically and histologically investigated in vivo. Three groups of titanium specimens were prepared: untreated titanium(S), acid-alkali treated titanium (H), and acid-alkali and heat-treated titanium(X). The oxide film of X surface resulted in more apatite formation and significantly higher strength of the interface between the samples and bone than those of the other titanium groups. The surface of the acid-alkali treated titanium and that further treated by heat treatment had higher bioactivity and stronger bone-bonding ability.

Abstract: Macrophages play a critical role in inflammatory response to implanted biomaterials and formation of restenosis. Macrophage adhesion may lead to macrophage activation and smooth muscle cell proliferation. Titanium oxide films on stainless steel are potential biomaterials for application to vascular stents. They have different influences on smooth muscle cell proliferation in in vivo tests, which could be the main reason for restenosis, but the mechanism is not clear. In this study we show that titanium oxide films can reduce inflammatory reaction with macrophages. Unstimulated macrophages release small amounts of chemical substance such as NO and give slight effect on smooth muscle cell proliferation.

Abstract: The titanium oxide layer with nano–micro hybrid structure on the titanium substrate was formed by grit-blasting and anodic oxidation treatment. A micro rough surface can be formed by grit-blasting and nanotube arrays can be formed by anodic oxidation or NaOH treatment after anodic oxidation. We investigated the surface characterization on titanium and the response of the osteoblast like cell (MG-63) to the surfaces made by different treatments. Surface structure (morphology), wettability characterized by SEM, contact angle. The attachment and proliferation behavior of MG-63 cells on the titanium surface by different surface treatments were characterized by SEM observation and MTT assay.The attachment and proliferation of osteoblast cells is accelerated by the topography of the nano structure like a nanotube, the nano surface acts as an attachment point for the filopodia of growing cells. Nano structure increases surface area and nano-micro structure significantly increases surface area. Such nano–micro hybrid structure on the titanium substrate can be useful for a well-adhered bioactive surface layer on Ti implant used metals for orthopedic and dental implants.

Abstract: Highly crystalline titania nano-particles were synthesized by hydrothermal method using novel stable water-soluble titanium complexes. It was confirmed that single phase anatase, rutile and brookite, which can be rarely synthesized as a single phase, can be obtained by varying the ligand in the complex and pH of the aqueous solution. TEM observations and BET specific surface area measurements had shown that these samples consisted of nanosized particles of 5~200 nm and had high specific surface areas of 25~150 m2/g. According to UV-visible diffuse reflectance spectra, these titania samples absorbed light in the visible region (λ > 400 nm). Photocatalytic activities in NO oxidation reaction exhibited by synthesized titania powders under the irradiation by UV- visible light were higher than the activity of the commercial TiO2 photocatalyst P25 (Degussa). Especially, under illumination by only visible light of above 510 nm wavelength, photocatalytic activity of the obtained specimens exceeded that of P25 more than four times. We also clearly demonstrated that single phase brookite had high photocatalytic activity for NO oxidation.

Abstract: Nano-scaled particle of anatase phase titanium oxide was obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment in oxygen. The crystal of ammonium oxofluorotitanate was grown on glass at 40oC with an aqueous solution of ammonium hexafluorotitanate and boric acid. The titanium oxide was obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment in oxygen. The size of nano-scaled anatase titanium oxide increases with the temperature of thermal treatment, and the size distribution is from 10 to 30 nm corresponding to the thermal temperature from 300 to 1000oC. The photocatalytic activity of the nano-scaled titanium oxide was demonstrated by the photo-deposition of copper in the solution of copper nitrate and sodium oxalate. The photocatalytic activity for the sample treated thermally at 800 oC is 1.3 times higher than that of commercial P-25.

Abstract: TiO2 coatings on ceramic substrate were prepared using TiOSO4 and silica sol. Coatings were then heat-treated respectively at 300°C, 400°C or 500°C for 30mins. Degradation of the solution of chlorinated methane by UV light and TiO2 coating were investigated. It can be concluded from the results that the coating with composition of 80wt%TiO2-20wt%SiO2 heated at 500°C display better degradation effect than the other coatings. As the initial concentration of chloromethane goes up, the degradation rate increases; while as the degree of substitution by chlorine goes up, the catalytic effects decreases.

Abstract: Sol-gel coatings of mixed TiO2-SiO2 had been deposited on ceramic substrates by spraycoating technique to study their hydrophilic and photocatalytic behavior on exposure to sunlight or ultraviolet illumination. The range of the films heat-treatment temperature is from 300°C to 500°C. AFM and XRD analysis were used to characterize the crystal structure and surface morphology of these coatings. Hydrophilic property was evaluated by water contact angle measurement under sunlight illumination condition, and photocatalytic activity by decomposition rate of aniline blue under ultraviolet illumination. Attrition resistance experiment was also carried out to test the hardness and adherence strength of these films. The experimental results demonstrate that this coating possesses high photo-activity and excellent adhesion to ceramic substrates.

Abstract: A co-precipitation preparation method and the properties of an ultraviolet (UV)-attenuating agent are described in this paper. The composite particles of ultra-fine zinc oxide and titanium oxide are used to attenuate UV radiation. Preparation of TiOSO4, ZnCl2 solution and the co-precipitation of the composite particles by alkali are included during the process. Various types of surfactants have been used to modify the composite particles. Particle sizes are determined by laser particle analyzer, and reflectance and absorption coefficient are determined by UV-VIS spectrophotometer. Results show that particle size of the composite particles as well as total reflectance and absorption coefficient depend on the surfactants, pH value, and carline temperature. The average sizes of zinc oxide and titanium oxide ultra-fine particles range from39 to 65 nm. Attenuation capability of ultraviolet radiation becomes stronger when the particle average sizes becomes smaller. Composites less than 40 nm with titanium oxide of rutile phase attenuate most effectively the ultraviolet radiation ranging from 280 nm to 390 nm.