Titanium Metal Sheet Research Articles

Synthesis and Characterization of TiO2 Nanotubes for High-Performance Gas Sensor Applications

In this study, we investigated the fabrication, properties, and sensing applications of TiO2 nanotubes. A pure titanium metal sheet was used to demonstrate how titanium dioxide nanotubes can be used for gas-sensing applications through the electrochemical anodization method. Subsequently, X-ray diffraction indicated the crystallization of the titanium dioxide layer. Scanning electron microscopy and transmission electron microscopy then revealed the average diameter of the TiO2 nanotubes to be approximately 100 nm, with tube lengths ranging between 3 and 9 µm and the thickness of the nanotube walls being about 25 nm. This type of TiO2 nanotube was found to be suitable for NO2 gas sensor applications. With an oxidation time of 15 min, its detection of NO2 gas showed a good result at 250 °C, especially when exposed to a NO2 gas flow of 100 ppm, where a maximum NO2 gas response of 96% was obtained. The NO2 sensors based on the TiO2 nanotube arrays all exhibited a high level of stability, good reproducibility, and high sensitivity.

Coupled cellular automata-crystal plasticity modeling of microstructure-sensitive damage and fracture behaviors in deformation of α-titanium sheets affected by grain size

Concerning the micro-scale deformation of titanium metal sheets, the number of grains in the sheet thickness direction decreases, and their formability exhibits a strong grain size sensitivity. Meanwhile, the twinning-induced dynamic recrystallization (TDRX) associated with grain size significantly affects the fracture behavior in the microforming of titanium sheets. Therefore, an accurate prediction of formability to improve manufacturing reliability remains challenging in the microforming of miniaturized titanium components. To address this issue, an in-depth understanding of the grain size-dependent TDRX behavior and its role in damage and fracture development in the microforming of α-titanium sheets is critical, and a coupled cellular automata-crystal plasticity (CA-CP) modeling framework was thus developed as an approach providing efficient solutions and insightful comprehensions of the issue. For the proposed modeling framework, a kinematic model for TDRX was established and integrated into the CP model by the CA algorithm. As a result, the microstructure evolution caused by TDRX was regarded as an intrinsic part of the constitutive behavior to connect heterogeneous plastic deformation and damage evolution through data transmission between the CP model and the CA algorithm. Additionally, the coupled CA-CP modeling framework was validated with the internal defect morphologies and deformation microstructures characterized by X-ray computed tomography (X-CT) and electron backscattered diffraction (EBSD). Experiment and simulation results demonstrated that the fine recrystallized (DRXed) grains were generated after the twin fragmentation when the dislocation density at twin boundaries reached a threshold of 9.2 × 1013 /m2. After TDRX, the dislocation density and the stress concentration intensity in recrystallization regions were revealed to decrease, accounting for the ductility improvement. Nevertheless, the dislocation density at twin boundaries was determined to decrease with the increase of grain size, leading to less twin fragmentation and the absence of TDRX. The uncoordinated deformation between fine DRXed grains motivated defects to grow spherically into microvoids, thereby preventing premature intergranular cracks along twins/grain boundaries. Ultimately, the deformation microstructures resulting from TDRX with the decrease of grain size were confirmed to control the brittle to ductile fracture transition of α-titanium sheets. The presented modeling framework and simulation procedure were validated to be able to predict the material integrity affected by crystalline microstructure in the deformation of titanium metal sheets.

Fabrication of Ti3SiC2/SiCp multiport minichannel plates for high-temperature applications

An innovative method for fabricating ceramic multiport minichannel plates (MMP) has been developed. The essence of the method is the combustion synthesis of Ti3SiC2/SiCp ceramic matrix composite using sandwich assembly of titanium metal items, viz. rods and sheets, and tape-cast rubber films filled with SiC particles and TiC additive. The fabrication route consists of hot pressing of starting materials at 100 °C under 60 MPa in air into a single integrated unit followed by heat treatment at 1400 °C in a vacuum hot press furnace under small uniaxial load of 80 N. It is shown that the one-dimensional titanium metal items act as both reactants and channel-forming templates. The MMP prepared by the proposed method contains primarily of 45 vol.% Ti3SiC2 and 44 vol.% SiC, as well 11 vol.% TiSi2 minor component. The material exhibits a composite microstructure consisting of a dense Ti3SiC2-based matrix and SiC particles uniformly embedded in it. The sample contains parallel-aligned hollow cylindrical channels of 0.8 mm in diameter distributed with a center-to-center spacing of 1.3 mm. The volume fracture of the channels is estimated to be about 19%.

Nitrogen and Transition-Metal Codoped Titania Nanotube Arrays for Visible-Light-Sensitive Photoelectrochemical Water Oxidation

The anodization of a titanium metal sheet to form aligned titanium dioxide nanotubes (TNTs) is of considerable research interest in fields such as photocatalysts, solar cells, and sensors due to their aligned nanostructure and high surface area [1]. Owing to wide band gap (3.2 eV) of TiO2, TNTs can utilize only UV, which is 3-4 % of solar light energy. It is an important issue to develop new TNTs with enhanced photocatalytic activities under visible-light irradiation. In the research field of TiO2 particles, impurity doping such as nitrogen is one of typical approaches to extend spectral response of TiO2 to visible light region [2]. Moreover, codoping of nitrogen and metal ion possesses potential to induce formation of new states which are close to the valence band and conduction band edges, respectively [3, 4]. The codoping approach is an efficient way to absorb wider spectrum of solar irradiation by TiO2 for photoelectrochemical water splitting for solar hydrogen generation and CO2 reduction reaction [5, 6]. In this work, we report on fabrication of novel TNT arrays codoped with nitrogen (N) and earth-abundant 3d-transition metals (TM) for visible-light-driven photoelectrochemical water oxidation. The fabrication method for N and TM (TM: Fe, V, Cr, or Co) codoped TNT [(N, TM)-TNT] arrays were via an anodization process using low concentration transition metal (0.05-0.13 at%)-Ti alloys and a subsequent nitridation process. Vertically aligned N and TM (TM: Fe, V, Cr, or Co) codoped TMT (N, M-TNT) with external diameter of ca. 100 nm and length of ca.3000 nm were successfully fabricated. XRD patterns of all (N, TM)-TNT samples have broad peaks assignable to the typical anatase phase. Photoelectrochemical measurements were performed in a 3-electrode cell containing 0.1 M KOH with a (N, TM)-TNT photoanode, a platinum cathode, and a Ag/AgCl reference electrode. The codoping of N and TM substantially improved the photocurrent of the TNT photoanode under visible light irradiation due to the formation of impurity levels by N and TM. The rate of increase in the photocurrent was dependent on transition metal species and it was found that codoping of iron showed the greatestest enhancement. N, Fe(0.13at%) codoped TNT [(N, Fe0.13)-TNT] photoanode modified with cobalt borate (Co-Bi) co-catalyst yielded a visible-light-induced water oxidation with a photocurrent density of 0.76 mA/cm2 at +0.6 V (vs. Ag/AgCl) under visible light irradiation, which was 13 times and 5 times higher than that of Fe0.13-TNT and N-TNT, respectively. In addition, O2 generation and the photocurrent were confirmed repeatedly during visible-light irradiation with high current efficiency (≥95%) and these results indicate that the observed photocurrent originated from water-splitting reaction [7]. The photoelectrochemical water oxidation activity of codoped TNT could be further improved by optimizing the amount of doping, kind of dopant, and nanotube structure. This scalable method for codoping to TNT can also be extended to other metal oxide nanotubes. [References] [1] P. Roy, et. al., Angew. Chem. Int. Ed., 50(2011) 2904. [2] R. Asahi, T. Morikawa, et al., Science, 293(2001) 269. [3] Y. Gai, J. Li, et al., Phys. Rev. Lett., 102(2009) 036402. [4] W. Zhu, et al., Phys. Rev. Lett., 103(2009) 226401. [5] S. Sato, T. Arai, et al., J. Am. Chem. Soc., 133(2011) 15240. [6] T. Arai, et al., Energy Environ. Sci., 6(2013) 1274. [7] T. M. Suzuki, et al., Chem. Commun., 50 (2014) 7614.

Fast Energy Relaxation by Trap States Decreases Electron Mobility in TiO2 Nanotubes: Time-Domain Ab Initio Analysis.

Highly ordered TiO2 nanotube arrays can be grown by simple electrochemical anodization of a titanium metal sheet, stimulating intense research and applications to solar cells and fuels. TiO2 nanotubes were expected to exhibit better electron transport than nanocrystal films. However, experiments showed that nanotubes provided little advantage over nanoparticles. Using nonadiabatic molecular dynamics, we demonstrate that oxygen vacancies, which are common in TiO2, accelerate nonradiative energy losses by an order of magnitude. Oxygen vacancies produce localized Ti(3+) states hundreds of millielectronvolts below the TiO2 conduction band. The states lower the nanotube band gap, trap excited electrons, induce stronger electron-phonon couplings, and facilitate the relaxation. Our results rationalize the unforeseen experimental observations and provide the atomistic basis for improving the structure and charge transport by TiO2 nanotubes.

Radiation grafting of acrylamide onto surface of dopamine functionalised titanium

Acrylamide (AAm) was grafted onto the surface of dopamine coated titanium metal sheet by the 60Co-γ irradiation method. The structure of the Ti surfaces was examined by Fourier transform infrared spectroscopy before and after grafting. Scanning electronic microscopy was employed to observe the surface morphologies, and hydrophilicity of the modified Ti surface was measured by water contact angle. Results showed that AAm was successfully grafted on the dopamine coated Ti sheet surface, and the complexed hydrophilic layer was firmly anchored on the Ti surface.

Effect of the compact Ti layer on the efficiency of dye-sensitized solar cells assembled using stainless steel sheets

Titanium films have been deposited on stainless steel metal sheets using dc magnetron sputtering technique at different substrate temperatures. The structure of the titanium films strongly depend on the substrate temperature. The titanium film deposited at the substrate temperature lower than 300°C has a loose flat sheet grains structure and the titanium film prepared at the substrate temperature higher than 500°C has a dense nubby grains structure. The DSSC assembled using stainless steel sheet coated with titanium film deposited at high substrate temperature has a low charge transfer resistance in the TiO2/Ti interface and results in a high conversion efficiency. The DSSC assembled using stainless steel sheet coated with titanium film deposited at temperature higher than 500°C has higher conversion efficiency than that assembled using titanium metal sheet as the substrate. The maximum conversion efficiency, 2.26% is obtained for DSSC assembled using stainless steel sheet coated with titanium film deposited at 700°C substrate temperature, which is about 70% of the conversion efficiency of the FTO reference cell used in this study.

Embedded Palladium Activation as a Facile Method for TiO2‐Nanotube Nanoparticle Decoration: Cu2O‐Induced Visible‐Light Photoactivity

Embedded Palladium Activation as a Facile Method for TiO₂‐Nanotube Nanoparticle Decoration: Cu₂O‐Induced Visible‐Light Photoactivity

Evaluation of microwave plasma oxidation treatments for the fabrication of photoactive un-doped and carbon-doped TiO2 coatings

The photoactivity of both un-doped and carbon-doped titanium dioxide (TiO2) coatings has been widely reported. In this paper, the use of a microwave plasma as a novel oxidation treatment for the fabrication of these coatings is evaluated. The photoactivity performance of the microwave plasma-formed coatings is benchmarked against those fabricated through air furnace oxidation as well as those deposited using reactive magnetron sputtering. The un-doped and carbon-doped TiO2 coatings were prepared respectively by microwave plasma-oxidizing titanium metal sheets and sputter deposited titanium carbide thin films. The resulting oxides were characterized using XPS, XRD, FEG-SEM, and optical profilometry. The oxide layer thicknesses achieved over the 15 to 45minute oxidation times were in the range of 0.15 to 3.44μm. These coatings were considerably thicker than those obtained by air furnace oxidation. The microwave plasma-formed oxides also exhibited significantly higher surface roughness values compared with the magnetron-sputtered coatings. The photoactivity performance of both un-doped and carbon-doped coatings was assessed using photocurrent density measurements. Comparing the un-doped TiO2 coatings, it was observed that those obtained using the microwave plasma oxidation route yielded photocurrent density measurements that were 4.3 times higher than the TiO2 coatings of the same thickness that were deposited by sputtering. The microwave plasma-oxidized titanium carbide coatings did not perform as well as the un-doped TiO2 probably due to the presence of un-oxidized carbide in the coatings, which reduced their photoactivity.

Thermal formation of silicon-doped TiO2 thin films with enhanced visible light photoelectrochemical response

Silicon-doped TiO2 thin films were fabricated by annealing titanium metal sheet embedded in SiO2 powders and characterized by X-ray photoemission spectroscopy and photoelectrochemical measurements. The results showed that the content of silicon in the doped TiO2 thin films was proportional to the annealing time and temperature. Enhanced visible light response, more negative flat band potential and higher carrier density were demonstrated by the electrochemical measurement. The technique proposed in this paper can be also applicable to fabricate other doped TiO2 thin films based on the corresponding oxide bath.

TiO2 Nanotubes: Synthesis and Applications

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

Non‐destructive investigation of fibronectin adsorption on titanium surfaces using PM‐RAIRS: effect of surface hydroxylation

AbstractPolarisation‐modulation reflection‐absorption infrared spectroscopy (PM‐RAIRS) is a useful non‐destructive technique to study semi‐quantitatively the adsorption of proteins on metal surfaces. In this work, we employed PM‐RAIRS to study the effect of the degree of hydroxylation of the surface of titanium metal sheets, obtained by specific acidic or basic treatments, on the adsorption of fibronectin, a model plasma adhesion protein. Our results seem to indicate that the degree of hydroxylation does not influence significantly the adhesion properties of fibronectin, which is one of the main steps in titanium osseointegration process. Copyright © 2010 John Wiley & Sons, Ltd.

광전기촉매 공정과 전기/UV 공정을 이용한 Rhodamine B의 색 제거

The feasibility study of the application of the photoelectrocatalytic and electrolytic/UV decolorization of Rhodamine B (RhB) was investigated in the photoelectrocatalytic and electrolytic/UV process with photoelectrode and DSA (dimensionally stable anode) electrode. Three types of photoelectrode were used. Thermal oxidation electrode (Th-) was made by oxidation of titanium metal sheet; sol-gel electrode (5G-) and powder electrode (P-) were made by coating and then heating a layer of titania sol-gel and slurry on titanium sheet. DSA electrodes were Ti and Ru/Ti electrode. The relative performance for RhB decolorization of each of the photoelecoodes and DSA electrodes is: Ru/Ti > Ti > SG- > Th-. It was observed that photoelectrocatalytic decolorization of RhB is similar to the sum of the photocatalytic and electrolytic decolorization. Therefore the synergetic effect was not showed in pthotoelectrocatalytic reaction. and NaCl showed different decolorization effect between pthotoelectrocatalytic and electrolytic/UV reaction. In the presence of the NaCl, RhB decolorization of Ru/Ti DSA electrode was higher than that of the other photoelectrode and Ti electrode. Optimum current, NaCl dosage and UV lamp power of the electrolytic/UV process (using Ru/Ti electrode) were 0.75 A, 0.5 g/L and 16 W, respectively.

Synthesis of a Perpendicular TiO2 Nanosheet Film with the Superhydrophilic Property without UV Irradiation

A method was developed for preparing perpendicular TiO2 nanosheet films from titanate nanosheet films produced on a titanium metal sheet by hydrothermal treatment with aqueous urea. The method is based on the consideration of some important points relating to the thermodynamics of nucleation and crystal growth. The resulting anatase TiO2 nanosheet films showed a specific superhydrophilicity without the need for any prior UV irradiation.

Texture Evolution during Diffusional Heat Treatment from Roll-Bonded Ti/Ni Laminates to TiNi Shape Memory Alloy Sheets

TiNi shape memory alloy thin sheets were produced from titanium and nickel metal sheets by a new processing consisting of repetitive roll-bonding and diffusional heat treatment. TiNi sheets after heat treatment at a relatively low temperature for a long time exhibited fairly isotropic and high shape-recoverable strain, because a near {111} B2-phase texture such as {223}<110> and {332}<113> was developed through reactive diffusion during heat treatment. In the early stage of reactive diffusion, intermetallic layers of Ti2Ni, TiNi and Ni3Ti were formed at once at the Ti/Ni interfaces of the roll-bonded laminate and then growth of a TiNi phase took place with the progress of interdiffusion. Texture of the final TiNi thin sheets, therefore, is derived from that of TiNi layers generated at the Ti/Ni interfaces, which is considered to have inherited rolling textures of Ni and Ti layers in the Ti/Ni laminate prior to reactive diffusion under orientation relationships on close-packed plane and direction between parent and product phases.

Photo-electrochemical properties of oxide semiconductors on porous titanium metal electrodes

Abstract For the purpose of producing hydrogen using solar energy, we investigated the potential of porous titanium metal sheet (PTMS) with high surface area for use as the basal plates for various types of oxide semiconductor photo-electrodes. The TiO 2 photoelectrodes were prepared by oxidation of PTMS and flat titanium metal sheet (FTMS). The photocurrents of the TiO 2 /PTMS electrodes were always higher than TiO 2 /FTMS under the same oxidation conditions. The reflectance of PTMS was lower than FTMS over the entire wavelength spectrum, suggesting that the scattered light was absorbed more effectively on the former. A nanocrystalline WO 3 layer-loaded PTMS electrode (WO 3 /PTMS) showed a high photocurrent compared to WO 3 /FTMS, suggesting that PTMS is highly suitable as basal plates for semiconductor photoelectrodes.

Photoelectrocatalytic destruction of organics using TiO 2 as photoanode with simultaneous production of H 2O 2 at the cathode

Research on the photoelectrocatalytic (PEC) oxidation of organic contaminants, the role of cathodes during photocatalysis has usually been disregarded. This paper reports a study of the PEC decomposition of aniline and salicylic acid with simultaneous production of hydrogen peroxide in a divided reactor using TiO 2 as a photoanode. Two types of TiO 2 electrode were used. Thermal oxidation electrodes (TO–TiO 2) were made by oxidation of titanium metal sheet; sol–gel electrodes (SG–TiO 2) were made by coating and then heating a layer of titania gel on titanium sheet. Saturated photocurrent was used to carry out an initial characterization and optimization of both electrode types. The best TO–TiO 2 electrodes were prepared by heating titanium at 600–700 °C in air. For the SG–TiO 2 electrodes, optimum performance was obtained by heating at 500 °C. These electrodes were then used to photodegrade aniline and salicylate. The SG–TiO 2 electrodes turned out to be superior to the TO–TiO 2 electrodes in terms of PEC rate under the same conditions but the difference in rate between the two electrodes was comparable under a high enough bias potential. The most important factors affecting the production of H 2O 2 in the cathode compartment are presented. The current efficiencies for the accumulation of H 2O 2 were remarkably affected by the cathode used, pH value, current density, and metal cations such as copper and iron ions. An expected H 2O 2 concentration could be obtained by controlling either the magnitude of the photocurrent or illumination time. The maximum current efficiency for the cathodic reduction of oxygen to H 2O 2 was as high as 90.1% when graphite was used as the cathode. Compared to the SG–TiO 2 electrode, the TO–TiO 2 electrode had a higher light to electricity conversion efficiency, thus it turned out to be more suitable for the production of H 2O 2. Furthermore, the role of in-situ reduced oxygen species in the PEC decomposition of aniline was evaluated.

Investigation of SnO 2 thin film evolution by thermoanalytical and spectroscopic methods

The thermal evolution process of a SnO 2 thin film from SnCl 2·2H 2O precursor dissolved in ethanol was followed by thermogravimetry combined with mass spectrometry (TG-MS), diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) and infrared emission spectrometry (IRES). The precursor salt solution was deposited on a titanium metal sheet. After evaporation of the solvent, the gel-like film was heated in a thermobalance in an oxidative environment to 600 °C. Mass spectrometric ion intensity curves showed the liberation of chlorinated species, alcoholic fragments and CO 2 as combustion product and from the decomposition of surface carbonyls, carboxylates and carbonates. The presence of O H, C H and C O bands in the infrared spectra was confirmed and their assignment was made by the deconvolution of the recorded curves as a function of the firing temperature.

Surface characterisation of plasma-nitrided titanium: an XPS study

DC plasma nitriding was applied to titanium metal sheets in a commercial cell using Ar + NH 3 as the admixture and the nitrided surface investigated by means of XPS. As a comparison, in situ nitriding of a chemically pure Ti surface at room temperature was performed by N 2 + ion bombardment (1–5 keV) in the electron spectrometer. Synthesis of the complex Ti2p envelope was accomplished using two sets of loss peaks, separated by 1.6 and 3.0 eV from the major TiN-type Ti2p 3 2 and Ti2p 1 2 components. A doublet at 458.8 and 464.5 eV was also included to account for a TiO 2-type oxide. The sum of the main Ti TiN peak and the two loss peaks were taken to be representative of nearly stoichiometric TiN x with x ranging from 0.85 to 1.15. Further components derived from the peak synthesis were assigned to TiN x O y and Ti 2O 3. The stoichiometric nitride is represented by a Ti2p doublet at binding energies of 454.7 and 460.6 eV and a single sharp N 1s peak at 396.7 ± 0.1 eV. On the superstoichiometric samples, especially after N 2 + bombardment, a second peak appears at about 395.8 eV with a positive correlation between this peak concentration and the relative amounts of species (TiN x O y , Ti 2O 3, TiO 2) derived from Ti2p components and the surface O and N content. Consecutive Ar +, N 2 + and (N 2 + + O 2 +) bombardment leads to significant changes in composition together with rearrangement of short-range chemical structure which is reflected in peak-shape changes of the Ti2p and N 1s lines.

Supported metal model catalyst surfaces examined by scanning tunnelling microscopy

SUMMARYTopographic and/or barrier‐height images of ultrafine Pt and Au metal particles supported on a vacuum‐deposited carbon film or titanium oxide thin films grown on titanium metal sheets were obtained. The topographic images of colloidal Au particles (5‐nm diameter) adsorbed on a titanium oxide thin film showed a structure elongated in the direction normal to the x scan, indicating their weak interaction with the support surface. The topographic images of Pt vacuum‐deposited on a carbon film showed c. 4‐nm diameter particles, larger than those observed in electron microscopy. The problems inherent to the STM observation of such dispersed metal systems are identified. In the case of Pt particles vacuum‐deposited on titanium oxide film, its barrier‐height image gave better indication of different phases on the surface than its topographic image. The significance of obtaining barrier‐height images along with topographic images for such sample systems is demonstrated.