Papers by Keyword: Titania

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Authors: Ming Chang, Juti Rani Deka, Chia Hung Lin, Chin Chung Chung
Abstract: One-dimensional (1D) nanostructure such as nanowires (NWs), nanobelts and nanorods have attracted tremendous attention in recent years due to their exceptional micro-structural properties and novel potential applications. In the present investigation, titania (TiO2) nanowires are synthesized by microwave hydrothermal process (MHP) treating TiO2 nano powder with NaOH inside a microwave oven for 5h at 210°C and 350W. The mechanical properties of as synthesized TiO2 nanowires are determined by bending it with a nanomanipulator inside a scanning electron microscope (SEM). Young’s moduli of the nanowires are measured to be approximately 11.870.923GPa.
Authors: Chi Sheng Chien, Yu Sheng Ko, Tsung Yuan Kuo, Tze Yuan Liao, Ting Fu Hong, Tzer Min Lee
Abstract: Hydroxyapatite (HA) is a frequently used bioactive coating material. However, when HA coating is soaked in the simulated body fluid (SBF), it is usually detached from substrate material due to its high dissolution rate in the solution. Recently, it is found that Fluorapatite (FA) has a better anti-dissolution ability than HA. In this study, Fluorapatite was mixed with TiO2 powder (either Anatase phase (A) or Rutile phase (R)) as a coating material precursor, and then be deposited on Ti-6Al-4V substrate to form the coating layer by using Nd-YAG laser cladding process. After soaking in SBF for various days, it is observed that dense ball-like apatite grew faster on the surface of the FA+R coating layer than that on the surface of the FA+A specimens. The corresponding Ca/P ratios of FA+R specimens also dropped faster than FA+A ones.
Authors: Sandrine Coste, Ghislaine Bertrand, Christian Coddet, Eric Gaffet, Horst Hahn, H. Sieger, M.A. Rodriguez, Cathy Meunier, Serge Vives
Abstract: Superior properties of nanostructured Al2O3 based materials, such as higher hardness and fracture toughness, have been evidenced. In order to optimize their manufacturing, the mechanical activation of the starting powders (Al2O3-TiO2 and Al2O3-ZrO2) was studied. In the present work, Al2O3 powders blended with 13wt% and 44wt% of titania or 20wt% and 80wt% of yttria partially stabilized zirconia have been high-energy ball-milled using a planetary mill, P4 (Fritsch) with steel vials and balls. The effect of the milling time and operating parameters, such as shock energy and friction to total energy ratio, on the powder structural and microstructural evolutions has been determined by SEM, XRD and BET. The transformation of the metastable anatase TiO2 phase into the high pressure TiO2 II phase and rutile phase was evidenced, simultaneously to the decrease of the alumina crystallite size, in the Al2O3-TiO2 system. In the Al2O3-ZrO2 system, the transformation of the monoclinic phase and the decrease of the alumina and tetragonal zirconia crystallite size have been observed.
Authors: Cavus Falamaki, Jamileh Veysizadeh
Abstract: The fabrication of thin nanoporous TiO2 layers (thickness < 2 μm) on functionally graded porous alumina (thickness = 2 mm) is reported for the first time. The membrane is produced by dip coating TiO2 sols on the alumina support. The alumina porous support is produced using centrifugal casting with an acceleration of 3000g .The average pore size of the support is ca. 0.5 μm while its upper surface on which the membrane layer is deposited has an average pore diameter of 0.38 μm and average porosity of 10.7 %. The sol is produced by the peptization technique using tetrapropylorthotitanate as precursor. For the first time, a synthesis procedure has been implemented which allows the production of TiO2 sols with average particle sizes from12 to 22 nm. Using the BET technique, the average pore size and meso-porosity of the unsupported sintered TiO2 membranes as a function of sintering temperature and ZrO2 impurity concentration (0.0, 0.2, 0.6 and 1.0 wt. % of ZrO2) have been determined. The kinetics of the membrane layer anatase to rutile transformation reaction has been investigated as a function of ZrO2 impurity concentration introduced to the TiO2 sol during its preparation. The lack of macrocraks in the ultrafilter layer of the sintered composite was confirmed using the gas permeability and SEM techniques. The main outcome of this work is that the support has an outstanding low surface roughness (< 0.4 μm) allowing deposition of a defect free single layer of TiO2 in one step
Authors: Bang Cheng Yang, Qi Feng Yu, Ji Yong Chen, Xing Dong Zhang
Abstract: The bioactivity of a composite of titania and hydroxyapatite was studied in vitro in this paper. After the titania ceramics was added 10% HA, it could induce apatite formation in simulated body fluid in 2d, while the pure titania ceramics could not induced apatite formation even after 14d. After the composite of titania and HA was subjected to alkali-heat treatment, it has a faster speed for apatite formation in SBF than the composite without treatment. When the osteoblast was cultured on the materials, the amount of osteoblasts attaching on the composite was more than that on the pure titania ceramics. It has the most osteoblasts cells on the composite subjected to alkali-heat treatment. These results showed that the composite of titania and HA is a bioactive materials, while the alkali-heat treatment could improved the bioactivity of this composite.
Authors: Satoshi Hayakawa, Keita Uetsuki, Akinori Kochi, Yuki Shirosaki, Akiyoshi Osaka
Abstract: A recently developed “GRAPE® technology” provides titanium or titanium alloy implants with spontaneous apatite-forming ability in vitro, which requires properly designed gaps and optimum heat treatment in air. In this study, pure titanium pieces were thermally oxidized in air and pre-irradiated by UV-light under different environmental conditions such as in air or in ultra-pure water before aligning pairs of specimens in the GRAPE® set-up, i.e., two pieces of titanium substrates were aligned parallel to each other with optimum gap width (spatial design). Then, they were soaked in Kokubo’s simulated body fluid (SBF, pH7.4, 36.5°C) for 1-2 days to clarify how the UV-light pre-irradiation affects the in vitro apatite nucleation on the substrates under the specific spatial design. UV-light pre-irradiation in water led to the deposition of a large number of apatite particles within 1 day, and showed apatite X-ray diffraction, although UV-light pre-irradiation in air and non-pretreated specimens gave the deposition of a few apatite particles and did not show any apatite X-ray diffraction. These results indicated that the rate of primary heterogeneous nucleation of apatite increased by UV-light pre-irradiation in ultra-pure water. TF-XRD patterns of the surface of the substrates thermally oxidized in air at 500°C showed the peak at 2θ = 27º assignable to the 110 diffraction of rutile phase of titanium dioxide (ICDD-JCPDS data #21-1276). Previous studies reported that the primary heterogeneous nucleation must be induced by Ti-OH groups on titanium oxide layer. Probably, the UV-light pre-irradiation in ultra-pure water can increase the number of Ti-OH groups on the surface, resulting in accelerated primary heterogeneous nucleation of apatite.
Authors: Xiang Ju Meng, Tatsuo Kimura, Tatsuki Ohji, Kazumi Kato
Abstract: Semi-crystalline mesoporous titania films were prepared by the reactions of titanium isopropoxide (TTIP) in acidic aqueous solutions containing EO106PO70EO106 triblock copolymer (F127) and 1,3,5-triisopropylbenzene (TIPBz). Adsorption experiments of dye molecules over the mesoporous films calcined at different temperatures and prepared with different TTIP/F127 molar ratios showed that adsorption property of the dye molecules would be related to the crystallinity of the frameworks and the macroporosity at the surfaces.
Authors: Guo Liang Shen, Gui Ling Ning
Abstract: A much simpler and more straightforward method, alcohol interchange for the synthesis of titanium glycolate has been suggested. The method implied the reaction of tetraethyl orthosilicate with ethylene glycol on heating in air. The thermal property of titanium glycolate was characterized by thermal gravimetric (TG) and Differencial Thermal Analysis (DTA) analysis. X-ray diffraction (XRD) was used to confirm the conversion of crystalline phase of titanium glycolate from anatase to rutile. The characterization of titanium glycolate and products of its pyrolysis was conducted using scanning electron microscopes.
Authors: Myoung Ryul Ok, Eun Young Kang, Ji Hye Kim, Young Su Ji, Chang Woo Lee, Young Joo Oh, Kyung Tae Hong
Abstract: Plasma electrolytic oxidation (PEO) has drawn attention and been studied intensively all through the world. The thick ceramic coatings fabricated by the technique exhibit excellent properties, including hardness and wear resistance, thermal and electrical insulation, and corrosion resistance, due to the characteristic phase composition and microstructure of the coating layers. However, most of the studies have dealt with manufacturing process itself and the apparent properties of coating layers and researches on the microstructural basis including transmission electron microscopy analysis are limited so far. In this investigation, a basic approach to PEO process was tried, adapting time-potential behavior analysis under constant current mode (galvanostatic) oxidation, and microstructural analysis on the coating structure, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The time-potential behavior analysis under constant current DC was carried out, and the resultant evolution of the microstructure was characterized..
Authors: Su Jun Yuan, Yao Gang Li, Qing Hong Zhang, Hong Zhi Wang
Abstract: The highly dispersed TiO2 sols composed of anatase crystallites (ca.5 nm) were prepared by peptization of amorphous precipitates with trifluoroactic acid (TFA) during the synthesis. The size and crystallinity of the particles were tuned by the subsequent hydrothermal treatment. The prepared TiO2 nanocrystals were characterized by X-ray diffraction and transmission electron microscopy (TEM). The TEM results indicated that the growth of the crystallites could be inhibited by the increasing addition of TFA and the average sizes of TiO2 nanocrystals were all ultrafine. The degradation of phenol over the nanocrystals after calcination at 500 °C was investigated. The photocatalytic results showed that the sample with a high addition of TFA obtained a better photocatalytic property than that of the commercial TiO2
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