Showing papers on "Titanium published in 2007"
9,432 citations
TL;DR: In this article, a self-standing 720 μm-thick TiO2 nanotubular membrane was constructed by double-sided electrochemical oxidation of titanium in an electrolyte comprised of water, NH4F, and ethylene glycol.
Abstract: We report on the anodic formation of a self-standing 720 μm thick TiO2 nanotubular membrane by complete consumption of a 250 μm thick titanium foil sample. By employing double sided electrochemical oxidation of titanium in an electrolyte comprised of water, NH4F, and ethylene glycol, we obtain two highly ordered, hexagonal close-packed titania nanotube arrays 360 μm in length that are separated by a thin compact oxide layer; the individual nanotubes in each array have an aspect ratio of ∼2200. The potentiostatic anodization of titanium in an ethylene glycol, NH4F, and water electrolyte dramatically increases the rate of nanotube array growth to approximately 15 μm/h, representing a growth rate ∼750−6000% greater than that seen, respectively, in other polar organic or aqueous based electrolytes previously used to form TiO2 nanotube arrays. We consider the effects of electrolyte composition, applied potential, and anodization duration on the length and diameter of the resulting nanotubes in terms of a growt...
584 citations
TL;DR: In this article, a self-aligned hexagonally closed-packed titania nanotube arrays of over 1000 μm in length and aspect ratio ≈10,000 by potentiostatic anodization of titanium were fabricated.
Abstract: We report for the first time fabrication of self-aligned hexagonally closed-packed titania nanotube arrays of over 1000 μm in length and aspect ratio ≈10 000 by potentiostatic anodization of titanium. We describe a process by which such thick nanotube array films can be transformed into self-standing, flat or cylindrical, mechanically robust, polycrystalline TiO2 membranes of precisely controlled nanoscale porosity. The self-standing membranes are characterized using Brunauer−Emmett−Teller surface area measurements, glancing angle X-ray diffraction, and transmission electron microscopy. In initial application, such membranes are used to control the diffusion of phenol red.
477 citations
TL;DR: Anatase, rutile and especially brookite nanocrystals have been selectively synthesized in this article via a redox route under mild hydrothermal conditions (180 °C, 3 h), employing trichloride as the titanium source and ammonium peroxodisulfate (APS), hydrogen peroxide, nitric acid, or perchloric acid as the oxidant.
Abstract: Anatase, rutile, and especially brookite nanocrystals have been selectively synthesized in this work via a redox route under mild hydrothermal conditions (180 °C, 3 h), employing trichloride as the titanium source and ammonium peroxodisulfate (APS), hydrogen peroxide, nitric acid, or perchloric acid as the oxidant. Characterizations of the three pure phases were achieved by XRD, Raman spectroscopy, FTIR, TG, HRTEM, UV−vis, and BET. The use of APS consistently yields anatase, but the particle morphology can be tuned from wormhole-structured agglomerates to more dispersed nanocrystallites. The use of other oxidants yields almost identical results, and phase selection can be attained in this case by controlling the reactant concentration and solution pH. The three phases show their distinctive crystal shapes: rounded nanocrystals for anatase, nanoplates for brookite, and nanorods for rutile. Both the optical band gap (3.11 eV) and the indirect band gap (2.85 eV) of brookite were found to lie in between thos...
382 citations
TL;DR: The Ti-Fe oxide nanotube array films are utilized in solar spectrum water photoelectrolysis, demonstrating 2 mA/cm2 under AM 1.5 illumination with a sustained, time-energy normalized hydrogen evolution rate by water splitting of 7.1 mL/W.
Abstract: In an effort to obtain a material architecture suitable for high-efficiency visible spectrum water photoelectrolysis, herein we report on the fabrication and visible spectrum (380-650 nm) photoelectrochemical properties of self-aligned, vertically oriented Ti-Fe-O nanotube array films. Ti-Fe metal films of variable composition, iron content ranging from 69% to 3.5%, co-sputtered onto FTO-coated glass are anodized in an ethylene glycol + NH4F electrolyte. The resulting amorphous samples are annealed in oxygen at 500 degrees C, resulting in nanotubes composed of a mixed Ti-Fe-O oxide. Some of the iron goes into the titanium lattice substituting titanium ions, and the rest either forms alpha-Fe2O3 crystallites or remains in the amorphous state. Depending upon the Fe content, the band gap of the resulting films ranges from about 380 to 570 nm. The Ti-Fe oxide nanotube array films are utilized in solar spectrum water photoelectrolysis, demonstrating 2 mA/cm2 under AM 1.5 illumination with a sustained, time-energy normalized hydrogen evolution rate by water splitting of 7.1 mL/W.hr in a 1 M KOH solution with a platinum counter electrode under an applied bias of 0.7 V. The surface morphology, structure, elemental analysis, optical, and photoelectrochemical properties of the Ti-Fe oxide nanotube array films are considered.
369 citations
TL;DR: In vivo results showed that increase of porosity and pore size, and thus increase of permeability of titanium alloy implants positively influenced their osteoconductive properties.
343 citations
TL;DR: In this article, the femtosecond laser surface treatment of titanium was performed in order to determine the potential of this technology for surface structuring of titanium implants, and they found that the femto-cond laser produces a large variety of nanostructures (nanopores, nanoprotrusions) with a size down to 20nm, multiple parallel grooved surface patterns with a period on the sub-micron level, microroughness in the range of 1-15μm with various configurations, smooth surface with smooth micro-inhomogeneities,
265 citations
TL;DR: In this paper, carbon-doped TiO2 microspheres and nanotubes have been synthesized via a single source chemical vapor deposition in an inert atmosphere and the effect of the temperature, substrate, and the flow rate of the carrier gas is investigated.
Abstract: Carbon-doped TiO2 micro-/nanospheres and nanotubes have been synthesized via a single source chemical vapor deposition in an inert atmosphere. Organic compound Ti(OC4H9)4 was used as the titanium, oxygen, and carbon source, while argon served as the carrier gas. The effect of the temperature, substrate, and the flow rate of the carrier gas is investigated. The diameter of the formed carbon-doped TiO2 spheres can be adjusted from 100 nm to several micrometers by varying the flow rate of the carrier gas. The as-prepared TiO2 nanotubes are highly ordered with a diameter of about 100 nm and a wall thickness of around 15 nm. The estimated optical band gap is 2.78 eV for the formed carbon-doped TiO2 microspheres and 2.72 eV for the synthesized carbon-doped TiO2 nanotubes, both of which are much smaller than that of bulk anatase TiO2 (3.20 eV). The photocurrent of the carbon-doped TiO2 spheres is much higher than that of commercial P-25, which is currently considered as one of the best TiO2 photocatalysts, espec...
263 citations
TL;DR: In this paper, a nanostructured porous TiO 2 interlayer was prepared on the aluminium alloy surface by controllable hydrolysis of titanium alkoxide in the presence of template agent.
262 citations
TL;DR: In this article, anatase TiO 2 nanotubes with diameters of about 10nm and lengths of 200-400nm were synthesized by a hydrothermal process, and the phase structure and morphology were analyzed by X-ray diffraction, Raman scattering, and transmission electron microscopy.
TL;DR: Corrosion performance of currently used metallic materials has been assessed and threat to the biocompatibility from corrosion products/metal ions is discussed and the possible preventive measures to improve corrosion resistance by surface modification and to increase the bioactivity of the metallic surfaces have been discussed.
Abstract: Metals, in addition to ceramics and polymers, are important class of materials considered for replacement of non-functional parts in the body. Stainless steel 316, titanium and titanium alloys, Co-Cr, and nitinol shape memory alloys are the most frequently used metallic materials. These alloys are prone to corrosion in various extents. This review briefly discusses the important biomaterials, their properties, and the physiological environment to which these materials are exposed. Corrosion performance of currently used metallic materials has been assessed and threat to the biocompatibility from corrosion products/metal ions is discussed. The possible preventive measures to improve corrosion resistance by surface modification and to increase the bioactivity of the metallic surfaces have also been discussed. Importance of the formation of oxide layers on the metal surface, another aspect of corrosion process, has been correlated with the host response. The gap areas and future direction of research are also outlined in the paper.
TL;DR: An overview of recent activities in this evolving area of Ti-TiB composites, covering processing, properties and potential applications, can be found in this paper, where the authors also provide an overview of the TiBw in-situ whisker reinforcements.
Abstract: Although titanium (Ti) alloys possess desirable properties such as specific strength, corrosion resistance and low density, their low specific stiffness and wear resistance have restricted their widespread application. Recently, composite strategies have provided means for overcoming these limitations. Titanium boride (TiBw) in-situ whisker reinforcements are currently recognized as one of the most compatible and effective reinforcements for Ti. This paper provides an overview of recent activities in this evolving area of Ti–TiB composites, covering processing, properties and potential applications.
TL;DR: In this article, the production of titanium foams using magnesium powders as spacer particles has been investigated and the resultant yield strength and elastic moduli values were observed to vary in the range 15-116 MPa and 0.42-8.8 GPa, respectively.
TL;DR: In this paper, an energetic model was proposed to explain the different growth behaviors with different precursors and density functional theory (DFT) calculation was made to find the intermediate product stability.
Abstract: Atomic layer deposition (ALD) of TiO2 thin films using Ti isopropoxide and tetrakis-dimethyl-amido titanium (TDMAT) as two kinds of Ti precursors and water as another reactant was investigated. TiO2 films with high purity can be grown in a self-limited ALD growth mode by using either Ti isopropoxide or TDMAT as Ti precursors. Different growth behaviors as a function of deposition temperature were observed. A typical growth rate curve-increased growth rate per cycle (GPC) with increasing temperatures was observed for the TiO2 film deposited by Ti isopropoxide and H2O, while surprisingly high GPC was observed at low temperatures for the TiO2 film deposited by TDMAT and H2O. An energetic model was proposed to explain the different growth behaviors with different precursors. Density functional theory (DFT) calculation was made. The GPC in the low temperature region is determined by the reaction energy barrier. From the experimental results and DFT calculation, we found that the intermediate product stability ...
TL;DR: Coating thickness, however, increased with time up to 2h of anodization, at which point an equilibrium thickness was established, and progressively higher values of elastic modulus were obtained for thinner films consistent with increasing effects of the Ti substrate.
TL;DR: In this article, anodic oxide films produced on commercially pure Ti by anodic oxidation with different voltages were analyzed and it was observed that porous titanium layers formed at all voltage values but morphological differences were observed.
TL;DR: In this article, the effects of titanium anodic oxidation in a sulphuric acid electrolyte on the crystallinity of the oxide layer and adjust the process parameters, in order to maximize the TiO2 crystalline phase, specially for what concerns the anatase form.
TL;DR: In this paper, it was found that the catalytic activity for the ORR of the Ti oxide catalysts increased with the increase in the specific crystalline structure, such as the TiO 2 (rutile) (1/1/0) plane and the work function.
TL;DR: This plasma polymer-functionalization of titanium is advantageous concerning osteoblastic focal adhesion formation as vinculin and paxillin, actin cytoskeleton development and, in consequence in differentiated cell functions, compared to a pure titanium surface-but similar such as the collagen I bonded surface via a polyethylenglycol-diacid (PEG DA)-spacer.
TL;DR: The use of titanium and titanium alloys for use in biomedical applications is reviewed, finding titanium exhibits superior corrosion resistance and tissue acceptance when compared with stainless steels and Cr-Co-based alloys.
Abstract: Titanium may be considered a relatively new engineering material. It was discovered much later than the other commonly used metals, its commercial application starting in the late 1940s. Its usage as an implant material began in the 1960s, despite the fact that titanium exhibits superior corrosion resistance and tissue acceptance when compared with stainless steels and Cr-Co-based alloys. This paper reviews the use of titanium and titanium alloys for use in biomedical applications.
TL;DR: The analyzed foams are found to be anisotropic due to the use of nonspherical space holder particles which rearrange during the compaction of the powder mixture.
Abstract: Open-pore titanium foams are produced using the so-called space holder method The mechanical properties of titanium foams with porosities of 50-80% are studied The stiffness and yield strength of the foams are found to encompass the property range between cancellous bone and cortical bone The analyzed foams are found to be anisotropic due to the use of nonspherical space holder particles which rearrange during the compaction of the powder mixture The titanium foams are stronger perpendicular to the compaction direction and weaker along the compaction axis In view of the application as an implant material in the lumbar spine, an intermediate porosity of 60-65% is analyzed more in detail The typical yield strength of titanium foam with 625% porosity is above 60 MPa in compression, bending, and tension Stiffness values vary with the testing method from 7-14 GPa
TL;DR: In this article, the authors evaluated the intergranular corrosion behavior of 316Ti and 321 austenitic stainless steels in relation to the influence exerted by modification of Ti, C and N concentrations.
TL;DR: These findings demonstrate the advantages of HPT-processed titanium over the conventional and coated titanium implants, as both mechanical properties and cellular response are improved.
TL;DR: In this paper, the authors investigated the response of titanium to oxidation at various temperatures and timings, in terms of layer thickness, phase evolution, surface morphology, oxide layer-substrate adhesion, hardness and tribological characteristics.
TL;DR: In this article, Nanocrystalline mesoporous N-doped titania films have been prepared for the first time and the introduction of nitrogen into the anatase structure starts at 500 °C, with N bonding to titanium via oxygen substitution.
Abstract: Nanocrystalline mesoporous N-doped titania films have been prepared for the first time. The introduction of nitrogen into the anatase structure starts at 500 °C, with N bonding to titanium via oxygen substitution. Increasing the treatment temperature leads to the formation of TiN (TiN 1-x O x ) and N-doped rutile showing mixed-valence Ti states. Microstructural characterization shows that the ordered mesoporosity is maintained until 700 °C, where TiN (TiN 1-x O x ) begins to form. Optical characterization shows that the discrete introduction of N is able to shift the titania absorption edge. The photocatalytic tests give the best results under visible light excitation for the film nitrided at 500 °C. At this temperature the concentration of nitrogen in the structure is optimal since oxygen vacancies are still not important enough to promote the recombination of the photogenerated electrons and holes.
TL;DR: In this paper, the effectiveness of polycrystalline diamond inserts (PCD) has been compared to that of uncoated tungsten carbide-cobalt inserts in machining titanium alloy Ti-6Al-4V, with respect to the applicable cutting speed ranges, metal removal per tool life and tool wear rates, tool wear morphology, surface finish, chip segmentation and chatter phenomena.
TL;DR: Catalytic dehydrogenation of R(2)NHBH(3) (R = Me, H) promoted by a family of bis(cyclopentadienyl)titanium and bis(indenyl)zirconium compounds is reported; structure-reactivity relationships as a function of cyclopentadiensyl and indenyl substituents have been examined.
25 Sep 2007-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a new type of wear resistant low carbon Fe-B cast steel with granular borides can be obtained by alloying with titanium and cerium rare earth (RE).
Abstract: A new type of wear resistant low carbon Fe–B cast steel with granular borides can be obtained by alloying with titanium and cerium rare earth (RE). As a result, the as-cast eutectic boride structures of Fe–B cast steel are greatly refined and a blocky, less interconnected boride network is obtained from continuous ledeburite. After heat treatment, the boride eutectic in the modified Fe–B cast steel is in the form of a granular boride structure that appears to be isolated particles The guide rollers made of modified low carbon Fe–B cast steel show excellent wear resistance and thermal fatigue resistance in high speed wire mills.