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Showing papers on "Titanium published in 2011"


Journal ArticleDOI
TL;DR: Based on the microstructure of titanium alloys, it can be divided into α-type titanium alloy, β-type alloy, and α+β-type alloys.

549 citations


Journal ArticleDOI
TL;DR: Effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications are discussed.
Abstract: β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants.

488 citations


Journal ArticleDOI
TL;DR: Clear evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems is provided and a methodological framework for collecting and analyzing titanium-based nanomaterials in complex wastewater matrices is offered.
Abstract: Titanium dioxide nanoparticles increasingly will be used in commercial products and have a high likelihood of entering municipal sewage that flows to centralized wastewater treatment plants (WWTPs). Treated water (effluent) from WWTPs flows into rivers and lakes where nanoparticles may pose an ecological risk. To provide exposure data for risk assessment, titanium concentrations in raw sewage and treated effluent were determined for 10 representative WWTPs that use a range of unit processes. Raw sewage titanium concentrations ranged from 181 to 1233 µg L−1 (median of 26 samples was 321 µg L−1). The WWTPs removed more than 96% of the influent titanium, and all WWTPs had effluent titanium concentrations of less than 25 µg L−1. To characterize the morphology and presence of titanium oxide nanoparticles in the effluent, colloidal materials were isolated via rota-evaporation, dialysis and lyophilization. High resolution transmission electron microscopy and energy dispersive X-ray analysis indicated the presence of spherical titanium oxide nanoparticles (crystalline and amorphous) on the order of 4 to 30 nm in diameter in WWTP effluents. This research provides clear evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems and offers a methodological framework for collecting and analyzing titanium-based nanomaterials in complex wastewater matrices.

374 citations


Journal ArticleDOI
02 Feb 2011-Langmuir
TL;DR: Two-tier micro- and nanoscale quasi-periodic self-organized structures, mimicking the surface of a lotus Nelumbo nucifera leaf, were fabricated on titanium surfaces using femtosecond laser ablation, revealing a highly selective retention pattern for two pathogenic bacteria.
Abstract: Two-tier micro- and nanoscale quasi-periodic self-organized structures, mimicking the surface of a lotus Nelumbo nucifera leaf, were fabricated on titanium surfaces using femtosecond laser ablation. The first tier consisted of large grainlike convex features between 10 and 20 μm in size. The second tier existed on the surface of these grains, where 200 nm (or less) wide irregular undulations were present. The introduction of the biomimetic surface patterns significantly transformed the surface wettabilty of the titanium surface. The original surface possessed a water contact angle of θW 73 ± 3°, whereas the laser-treated titanium surface became superhydrophobic, with a water contact angle of θW 166 ± 4°. Investigations of the interaction of S. aureus and P. aeruginosa with these superhydrophobic surfaces at the surface−liquid interface revealed a highly selective retention pattern for two pathogenic bacteria. While S. aureus cells were able to successfully colonize the superhydrophobic titanium surfaces, ...

360 citations


Journal ArticleDOI
TL;DR: In this article, the authors reviewed and compared various metallurgical processes for titanium dioxide and titanium metal, mainly focusing on the future development of hydrometallurgical process for titanium metal.

350 citations


Journal ArticleDOI
TL;DR: In this study the necessary SLM processing conditions to obtain a dense product were investigated using a Ti powder of less than 45 μm particle size, showing that a fully dense plate thinner than 1.8 mm was obtained when the laser power to scanning speed ratio was greater than 0.5.

311 citations


Journal ArticleDOI
TL;DR: The results show that the physico-chemical properties of the Ag NPs are important in the control of the cytotoxicity and this study opens a new window for the design of nanostructured surfaces on which the biological actions of theAg NPs can be accurately tailored.

305 citations


Journal ArticleDOI
TL;DR: Zirconia dental implants have the potential to become alternative dental implants to titanium dental implants, but they are not yet in routine clinical use, and information on zirconian dental implant osseointegration and mechanical strength is provided.
Abstract: Titanium and titanium alloys are widely used for fabrication of dental implants. Because of potential immunologic and possible esthetic compromises with titanium implants, novel implant te...

273 citations


Journal ArticleDOI
TL;DR: This work uses quantum mechanics to understand how titanium, zirconium, silicon, or germanium n-type doping affects the electron transport mechanism in hematite and suggests that use of n- type dopants that easily ionize completely or promote covalent bonds to oxygen can provide more charge carriers while not inhibiting transport.
Abstract: Hematite (α-Fe2O3) is a promising candidate for photoelectrochemical splitting of water. However, its intrinsically poor conductivity is a major drawback. Doping hematite to make it either p-type or n-type enhances its measured conductivity. We use quantum mechanics to understand how titanium, zirconium, silicon, or germanium n-type doping affects the electron transport mechanism in hematite. Our results suggest that zirconium, silicon, or germanium doping is superior to titanium doping because the former dopants do not act as electron trapping sites due to the higher instability of Zr(III) compared to Ti(III) and the more covalent interactions between silicon (germanium) and oxygen. This suggests that use of n-type dopants that easily ionize completely or promote covalent bonds to oxygen can provide more charge carriers while not inhibiting transport.

266 citations


Journal ArticleDOI
TL;DR: In this article, a tridoped TiO2 was synthesized using a facile, cost-effective and easily scaled-up sol-gel method with titanium butoxide (Ti(OC4H9)4) as titanium precursor and thiourea as the dopant source.
Abstract: C–N–S tridoped TiO2 was synthesized using a facile, cost-effective and easily scaled-up sol–gel method with titanium butoxide (Ti(OC4H9)4) as titanium precursor and thiourea as the dopant source. It was found that thiourea could suppress the crystal growth of the anatase TiO2 and inhibit its transformation from anatase to rutile phase. X-ray photoelectron spectroscopy (XPS) analysis revealed that carbon substituted some of the oxygen to form Ti–C bonds, nitrogen was interstitially and substitutionally doped into the TiO2 lattices to form Ti–N–O, Ti–O–N and O–Ti–N, and S6+ substituted for the lattice Ti4+ to result in cationic sulfur doping. The photocatalyst with the thiourea-to-Ti molar ratio of 0.05:1 and calcined at 450 °C (T0.05–450) possessed the optimum surface elemental contents of C (12.56 at.%, excluded adventitious carbon at 284.8 eV), N (0.54 at.%) and S (1.60 at.%) based on the XPS analysis, and exhibited the highest photocatalytic degradation efficiency of tetracycline (TC) under visible-light irradiation. This was attributed to the synergistic effects of TC adsorption on T0.05–450 due to its high specific surface area, band gap narrowing resulting from C–N–S tridoping, presence of carbonaceous species serving as photosensitizer, and well-formed anatase phase. The slightly alkaline pH condition and solar irradiation were more favorable for both the photocatalytic degradation and mineralization of TC. Microtox assay indicated that the extended solar photocatalysis was efficient in the detoxification of TC solution.

259 citations


Journal ArticleDOI
TL;DR: In this article, surface modification of titanium and titanium alloys by ion beam implantation is described, where surface treatment that would elicit favorable response from tissues can be applied to enhance the usefulness of the implants.

Journal ArticleDOI
J. M. Wang1, Ning Du1, Hui Zhang1, Jingxue Yu1, Deren Yang1 
TL;DR: In this article, a large-scale synthesis of SnO2 nanotube arrays on titanium substrate via ZnO nanowire arrays as sacrificial templates is presented, which feature the large surface area, good electronic conductivity, and adhesion with the current collector, leading to the enhanced performance in lithium-ion batteries.
Abstract: This paper presents the large-scale synthesis of SnO2 nanotube arrays on titanium substrate via ZnO nanowire arrays as sacrificial templates. The SnO2 nanotube arrays on titanium substrate feature the large surface area, good electronic conductivity, and adhesion with the current collector, leading to the enhanced performance in lithium-ion batteries.

Journal ArticleDOI
TL;DR: In this paper, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical applications were assessed in terms of their surface properties electrochemical corrosion in simulated body fluid and cytotoxicity.
Abstract: In the present study, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical applications were assessed in terms of their surface properties electrochemical corrosion in simulated body fluid and cytotoxicity. Layers of TiN, TiON and TiAlN were deposited onto CP–Ti substrates by DC reactive magnetron sputtering method using a combination of a Ti, Ti–Al targets and an Ar–N 2 mixture discharge gas. The presence of different phases was identified by XRD analysis. The morphology was determined through atomic force microscopy (AFM) imaging. The XPS survey spectra on the etched surfaces of TiN film exhibited the characteristic Ti2p, N1s, O1s peaks at the corresponding binding energies 454.5, 397.0, and 530.6 eV respectively. The characteristic Raman peaks were observed from the Laser Raman spectrometer. Platelet adhesion experiments were done to examine the interaction between blood and the materials in vitro. On Control samples (CP Ti), platelets were seen as aggregates, whereas on coated samples, platelets were seen as singles, without any significant spreading. Cytocompatibility studies of coated samples were carried out with bare titanium (CP Ti — ASTM B 348) as controls. L-929 mouse fibroblast cells were used for samples. All materials showed good cytocompatbility with cell lines used.

Journal ArticleDOI
TL;DR: Preparation of a highly crystalline nano hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray and their in vitro and in vivo biological response are reported.
Abstract: This paper reports preparation of a highly crystalline nano hydroxyapatite (HA) coating on commercially pure titanium (Cp-Ti) using inductively coupled radio frequency (RF) plasma spray and their in vitro and in vivo biological response. HA coatings were prepared on Ti using normal and supersonic plasma nozzles at different plate powers and working distances. X-ray diffraction (XRD) and Fourier transformed infrared spectroscopic (FTIR) analysis show that the normal plasma nozzle lead to increased phase decomposition, high amorphous calcium phosphate (ACP) phase formation, and severe dehydroxylation of HA. In contrast, coatings prepared using supersonic nozzle retained the crystallinity and phase purity of HA due to relatively short exposure time of HA particles in the plasma. In addition, these coatings exhibited a microstructure that varied from porous and glassy structure at the coating-substrate interface to dense HA at the top surface. The microstructural analysis showed that the coating was made of multigrain HA particles of ~200 nm in size, which consisted of recrystallized HA grains in the size range of 15- 20 nm. Apart from the type of nozzle, working distance was also found to have a strong influence on the HA phase decomposition, while plate power had little influence. Depending on the plasma processing conditions, a coating thickness between 300 and 400 μm was achieved where the adhesive bond strengths were found to be between 4.8 MPa to 24 MPa. The cytotoxicity of HA coatings was examined by culturing human fetal osteoblast cells (hFOB) on coated surfaces. In vivo studies, using the cortical defect model in rat femur, evaluated the histological response of the HA coatings prepared with supersonic nozzle. After 2 weeks of implantation, osteoid formation was evident on the HA coated implant surface, which could indicate early implant- tissue integration in vivo.

Journal ArticleDOI
02 Sep 2011-Wear
TL;DR: In this article, the wear mechanisms of tungsten carbide (WC) and polycrystalline diamond (PCD) drills when drilling carbon fiber reinforced plastics (CFRP) stacked on top of titanium (Ti) were investigated.

Journal ArticleDOI
TL;DR: In this article, a high thermal conductivity of 493 Wm−m−1 K−1 was achieved in the Cu/Ti-coated diamond composites, attributed to the 285nm thick Ti coating.

Journal ArticleDOI
TL;DR: This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.
Abstract: Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.

Journal ArticleDOI
TL;DR: The surface modification of two kinds of TiO2 particles with highly dispersed iron oxides by the CCC technique gives rise to a high level of visible-light-induced activity and greatly heightens the activity under UV-light irradiation.
Abstract: TiO2 has three polymorphic forms: anatase, rutile, and brookite. Anatase usually has the highest photocatalytic activity under illumination of UV light; the activity can further be improved by coupling with rutile. The development of a general method for endowing commercial anatase and anatase–rutile composite TiO2 with visible-light response and concomitantly increasing their UV-light activity should dramatically expand their viability. To this end, doping of various transition metals and anions has been extensively studied. In particular iron, which is harmless and abundant in nature is an ideal candidate; however, the positive doping effect is only limited to TiO2 particles smaller than 10 nm in diameter. This limit mainly arises because the doping generates impurity and/or vacancy levels in the bulk, which act as the recombination centers. As an alternative, Kisch et al. have devised the photosensitization of TiO2 by surface modification with platinum(IV) chloride. This approach is attractive in that the visible-light response can be induced by the simple procedure without introduction of the impurity/ vacancy levels. Recently, the research groups of Ohno and Hashimoto have shown that the surface modification of rutile TiO2 with Fe 3+ by the impregnation method leads to high visible-light activities for the decomposition of model organic pollutants. However, the effect is small for anatase TiO2. On the other hand, we have developed the chemisorption–calcination cycle (CCC) technique, in which metal complexes are adsorbed by chemical bonds and the organic (ligand) part is oxidized by post-heating to prepare metal oxide clusters and ultrathin films at a molecular scale. Herein we show that the surface modification of two kinds of TiO2 particles (see the Experimental Section) with highly dispersed iron oxides by the CCC technique ((FeOx)m/TiO2) gives rise to a high level of visible-light-induced activity and greatly heightens the activity under UV-light irradiation. [Fe(acac)3] was adsorbed on the TiO2 surface by a partial ligand exchange between the acetylacetonate and surface OH groups [Equation (1)]

Journal ArticleDOI
TL;DR: It was revealed by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopic characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.
Abstract: In this study, titanium nitride-vanadium nitride fibers of core–shell structures were prepared by the coaxial electrospinning, and subsequently annealed in the ammonia for supercapacitor applications. These core–shell (TiN-VN) fibers incorporated mesoporous structure into high electronic conducting transition nitride hybrids, which combined higher specific capacitance of VN and better rate capability of TiN. These hybrids exhibited higher specific capacitance (2 mV s–1, 247.5 F g–1) and better rate capability (50 mV s–1, 160.8 F g–1), which promise a good candidate for high-performance supercapacitors. It was also revealed by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) characterization that the minor capacitance fade originated from the surface oxidation of VN and TiN.

Journal ArticleDOI
TL;DR: In this paper, hole quality/integrity following drilling of titanium/CFRP/aluminium stacks under flood cutting fluid and spray mist environments was investigated. But the results showed that the CFRP layer typically produced dusty black composite particles suspended in the soluble oil of the coolant emulsion, while delamination was significantly reduced when machining CFRP in the stack configuration.
Abstract: The use of material stacks comprising titanium, carbon fibre reinforced plastics (CFRPs) and aluminium is expanding for structural aerospace applications, especially where high mechanical loads exist such as for aircraft wing and tail-plane components. Here, the production of bolt/fixation holes is essential to the manufacturing process in order to facilitate part assembly. The paper outlines an analysis of hole quality/integrity following drilling of titanium/CFRP/aluminium stacks under flood cutting fluid and spray mist environments. Uncoated and coated (CVD diamond and hardmetal) tungsten carbide drill performance is evaluated against key response measures including hole size, out of roundness, cylindricity, burr height, hole edge quality, average surface roughness (Ra), microhardness (of the metallic elements) and swarf morphology. Burr height (up to 0.5 mm) was observed to be greater at the hole exit (aluminium) compared to hole entry (titanium) while delamination was significantly reduced when machining CFRP in the stack configuration as opposed to a standalone arrangement. Spiral shaped continuous aluminium swarf was prevalent while both short and long helical chips were found with the titanium material when cutting wet. In contrast, the CFRP layer typically produced dusty black composite particles suspended in the soluble oil of the coolant emulsion.

Journal ArticleDOI
TL;DR: In this article, a stable superhydrophobic film was prepared on the electrochemical oxidized titania/titanium substrate by a simple immersion technique into a methanol solution of hydrolyzed 1 H,1 H,2 H,2 H -perfluorooctyltriethoxysilane [CF 3 (CF 2 ) 5 (CH 2 ) 2 Si(OCH 2 CH 3 ) 3, PTES] for 1-h at room temperature followed by a short annealing at 140-°C in air for 1 -h

Journal ArticleDOI
TL;DR: It is suggested that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest and it is plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblast.
Abstract: This work considers the adhesion of cells to a nanorough titanium implant surface with sharp edges. The basic assumption was that the attraction between the negatively charged titanium surface and a negatively charged osteoblast is mediated by charged proteins with a distinctive quadrupolar internal charge distribution. Similarly, cation-mediated attraction between fibronectin molecules and the titanium surface is expected to be more efficient for a high surface charge density, resulting in facilitated integrin mediated osteoblast adhesion. We suggest that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest. It is therefore plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblasts.

Journal ArticleDOI
TL;DR: A facile process to prepare well-defined anatase TiO2 crystals with predominantly exposed high-index {105} facets, which have never been realized experimentally before are reported.
Abstract: Put your best face forward: The performance of TiO2 anatase crystals in energy and environmental applications is normally correlated with the TiO2 crystal facets exposed, and increasing the percentage of highly reactive surfaces is extremely important. A new gas-phase oxidation process using TiCl4 as precursor now yields anatase TiO2 single crystals with primarily high-index {105} facets, which can cleave water photocatalytically. Inorganic functional materials with tailor-made crystal facets have attracted great research interest owing to their applications in catalysis, sensors, batteries, and environmental remediation.1–6 Unfortunately, the surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. Thus, increasing the percentage of known highly reactive surfaces or creating new favorable surfaces is highly desirable. Crystalline titanium dioxide (TiO2) in the anatase phase is one of the most important semiconducting metal oxides, owing to its many promising energy and environmental applications.7–9 Conventionally, anatase TiO2 crystals are dominated by the thermodynamically stable {101} facets (ca. 94 percent, according to the Wulff construction) and a minority of {001} facets.10 Recently, we developed a new strategy to synthesize anatase TiO2 crystals with a large percentage of highly reactive {001} facets using fluorine-containing compounds, such as hydrofluoric acid, as capping agents, which made {001} energetically preferable to {101}.4 Gas-phase reactions with rapid heating and quenching were also reported recently to generate {001}-faceted decahedral anatase TiO2 crystals.11 Most recently, photocatalytically active {100} facets of anatase TiO2 crystals were synthesized using solid sodium titanates as the titanium source under hydrothermal conditions.12 However, all these breakthroughs contribute to the increase of the percentage of known low-index {001} or {100} facets only, which are the basic crystal surfaces in the Wulff construction model of anatase in a thermodynamically stable state and have been evidenced theoretically and experimentally.13 Because they usually have unique surface atomic structures, such as a high density of atomic steps, dangling bonds, kinks, and ledges, that can act as active sites, high-index planes of anatase may have the capability to be used in clean-energy and environmental applications. Unfortunately, owing to the high surface energies, which can lead to the elimination of high-index crystal planes, it is still an open challenge to synthesize tailor-made anatase TiO2 crystals bounded by high-index facets. Herein we report a facile process to prepare well-defined anatase TiO2 crystals with predominantly exposed high-index {105} facets, which have never been realized experimentally before. The anatase TiO2 crystals with exposed high-index {105} facets were prepared by a modified hightemperature gas-phase oxidation route using titanium tetrachloride (TiCl4) as the Ti source.11 A schematic reaction apparatus is given in Figure S1 in the Supporting Information. A straight static furnace pipe and a thin spiral tube were used as reactor and reactant feeder, respectively. In a typical experiment, the vapor-phase TiCl4 was liberated by bubbling oxygen (0.2 L min−1) into TiCl4 liquid at 98 °C and then passed through the furnace pipe at a temperature of 1000 °C. The experimental process was shown to be quite robust, and the reproducible synthesis of the anatase TiO2 crystals with exposed high-index {105} facets was also confirmed. Moreover, key synthesis conditions such as concentration of titanium precursor, reaction temperature, and oxygen flow were also explored extensively. In all experiments, the final white products were collected downstream by a bag filter and washed with deionized water three times to remove the adsorbed chlorine-containing species on the surface. Gram-scale production can be easily achieved if a furnace pipe with a diameter of about 5 cm is used (Figure S2 in the Supporting Information for digital camera images of the final white powder). Figure 1 shows the X-ray diffraction (XRD) pattern of the as-synthesized TiO2 crystals with exposed high-index {105} facets. All the main diffraction peaks can be indexed to the anatase crystal phase (space group I41/amd, JCPDS No. 21-1272), and only a very small amount of rutile impurity can be detected. Moreover, the peak indexed to {105} facets exhibits a higher intensity than in the calculated diffraction pattern of bulk anatase, which indicates that more {105} facets have been exposed (the corresponding peak has been marked with an asterisk (*) in Figure 1). Scanning electron microscopy (SEM) images in Figure 2 a–c show that the synthesized anatase TiO2 crystals display bipyramidal morphology with an average length of 2.42 μm (Figure S3 for the size distribution of these TiO2 crystals). The 3D schematic shape of a typical anatase TiO2 bipyramidal crystal with only high-index {105} facets exposed is shown in Figure 2 d. Statistically, the average interfacial angle indicated in Figure 2 d is 26.67°, which is close to that of {105} and {001} facets. The surfaces of all the crystals are very smooth, and some minority {101} facets can also be found occasionally, as indicated in Figure 2 b and Figure S4 in the Supporting Information. According to the symmetries of anatase TiO2, it can be concluded that the eight triangular surfaces in the bipyramidal crystals must be the high-index (105) facets. A transmission electron microscopy (TEM) image of a free-standing anatase TiO2 bipyramidal crystal and its corresponding selectedarea electron diffraction (SAED) pattern (Figure 3 a, b) demonstrate the single-crystal characteristics. The high-magnification TEM image in Figure 3 c clearly shows the (200) and (020) atomic planes with a lattice spacing of 0.189 nm. It should be noted that both the SAED pattern and the high-magnification TEM image were indexed along the [001] crystallographic direction of

Journal ArticleDOI
TL;DR: A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed.
Abstract: A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed. The method using passive surface oxide film on titanium takes advantage of the fact that the surface film on Ti consists mainly of amorphous or low-crystalline and non-stoichiometric TiO2. In another method, the reconstruction of passive films, calcium phosphate naturally forms on Ti and its alloys, which is characteristic of Ti. A third method uses the surface active hydroxyl group. The oxide surface immediately reacts with water molecules and hydroxyl groups are formed. The hydroxyl groups dissociate in aqueous solutions and show acidic and basic properties. Several additional methods are also possible, including surface modification techniques, immobilization of poly(ethylene glycol), and immobilization of biomolecules such as bone morphogenetic protein, peptide, collagen, hydrogel, and gelatin.

Journal ArticleDOI
TL;DR: In this paper, the effect of propellant gas, helium, and nitrogen during cold spraying of titanium coatings was investigated, and the results showed that for the same particle velocity, DE and coating density are also a function of substrate temperature.
Abstract: This study investigates the effect of propellant gas, helium, and nitrogen during cold spraying of titanium coatings. Coatings were characterized by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated in which for each condition, the propelling gases’ temperature and pressure were attuned to attain similar particle velocities for each gas. Observations show that loosely bonded particles can be detached by high-pressure supersonic gas stream. Selected coatings were characterized by XPS to analyze the occurrence of oxidation and nitridation. Although generally accepted that coating characteristics can be affected by particle temperature, results show that for the same particle velocity, DE and coating density are also a function of substrate temperature. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimized spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s.

Journal ArticleDOI
TL;DR: In this paper, the phase transformations of TiO2 nanotubes on a Ti substrate and that of freestanding TiO 2 membranes during the calcinations process were studied by scanning electron microscopy and X-ray diffraction microscopy.

Journal ArticleDOI
TL;DR: In this article, the effectiveness of carbon dioxide snow (CO2) as a coolant for turning Ti-10V-2Fe-3Al was analyzed and compared to flood emulsion cooling the flank wear was uniform spreaded and tool life was increased by a factor of two even at higher cutting speeds.

Journal ArticleDOI
TL;DR: In this paper, a low-cost, new material, eco-friendly and reproducible microbes Bacillus subtilis mediated biosynthesis of TiO2 nanoparticles was reported.

Journal ArticleDOI
TL;DR: In this article, a ligand-assisted assembly approach is demonstrated for the synthesis of thermally stable and large-pore ordered mesoporous titanium dioxide with a highly crystalline framework by using diblock copolymer poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template and titanium isopropoxide (TIPO) as precursor.
Abstract: A novel ligand-assisted assembly approach is demonstrated for the synthesis of thermally stable and large-pore ordered mesoporous titanium dioxide with a highly crystalline framework by using diblock copolymer poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template and titanium isopropoxide (TIPO) as a precursor. Small-angle X-ray scattering, X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution scanning electron microscopy, and N2-sorption measurements indicate that the obtained TiO2 materials possess an ordered primary cubic mesostructure with large, uniform pore diameters of about 16.0 nm, and high Brunauer–Emmett–Teller surface areas of ∼112 m2 g−1, as well as high thermal stability (∼700 °C). High resolution TEM and wide-angle XRD measurements clearly illustrate the high crystallinity of the mesoporous titania with an anatase structure in the pore walls. It is worth mentioning that, in this process, in addition to tetrahydrofuran as a solvent, acetylacetone was employed as a coordination agent to avoid rapid hydrolysis of the titanium precursor. Additionally, stepped evaporation and heating processes were adopted to control the condensation rate and facilitate the assembly of the ordered mesostructure, and ensure the formation of fully polycrystalline anatase titania frameworks without collapse of the mesostructure. By employing the obtained mesoporous and crystallized TiO2 as the photoanode in a dye-sensitized solar cell, a high power-conversion efficiency (5.45%) can be achieved in combination with the N719 dye, which shows that this mesoprous titania is a great potential candidate as a catalyst support for photonic-conversion applications.

Journal ArticleDOI
TL;DR: In this article, the photoanodes were measured as a function of titanium concentration and the incident photon-to-current conversion efficiency (IPCE) to hydrogen was measured in alkaline electrolyte.
Abstract: To improve the optoelectronic properties of iron oxide as a photoelectrode, hematite (α-Fe2O3) thin films were doped with titanium using atmospheric pressure chemical vapor deposition (APCVD) for synthesis. The films were prepared by pyrolysis of Fe(CO)5 and TiCl4 precursors on fluorine-doped tin oxide (FTO) substrates and found to have a polycrystalline morphology with faceted particulates ∼20 to 50 nm in size with a preferred crystallographic growth along the [110] direction. The performance of the photoanodes was measured as a function of titanium concentration. A maximum efficiency was observed at ∼0.8 atom% Ti in hematite. The Incident Photon-to-current Conversion Efficiency (IPCE) to hydrogen was measured in alkaline electrolyte. Under an applied bias of 0.6 V vs.Ag/AgCl at 400 nm the IPCE for water splitting in alkaline solution was found to be 27.2%, the highest efficiency reported for Ti doped hematite photoanodes. The IPCEs of the photoanode thin films at lower applied bias were further increased by calcination at 500 °C and by use of glucose as an anolyte.