High Titanium Research Articles

Unravelling camphor mediated synthesis of TiO2 nanorods over shape memory alloy for efficient energy harvesting

We demonstrated a cost-effective and scalablechemical vapor deposition(CVD) process for the production of high quality and dense rutile titanium dioxide nanorods (R-TiO2 NR) based on camphor (Cinnamomum camphora) decomposition overshape memory alloy (nitinol). The topography of the camphor-based R-TiO2 NR was studied underfield emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) which revealed high coverage of R-TiO2 NR over the substrate. The phase purity of R-TiO2 NR was established by X-ray diffraction measurements performed at different camphor concentrations and substrate temperatures. Raman spectroscopy and X-ray photoelectron spectroscopyconfirmed the chemical and the elemental composition of the nanorods grown over nitinol, which suggest the formation of high-quality R-TiO2 NR. Further, R-TiO2 NR was used as photoanode in 1 M KOH solution for efficient energy harvesting application by indicating a high photocurrent density of 550 µA/cm2 at 1.23 V vs RHE (reversible hydrogen electrode), indicating excellent light trapping mechanism with efficient charge separation and extraction. The proposed CVD process is a suitable method for large scale production of R-TiO2 NR over nitinol, which can be potentially employed in sensors and various other biomedical applications.

Modeling Viscosity of High Titania Slag

TiO2-FeO-Ti2O3 slag system is the dominant system for industrial high-titania slag production. In the present work, viscosities of TiO2-FeO and TiO2-FeO-Ti2O3 systems were experimentally determined using the concentric rotating cylinder method under argon atmosphere. A viscosity model suitable for the TiO2-FeO-Ti2O3 slag system was then established based on the modification of the Vogel-Fulcher-Tammann (VFT) equation. The experimental results indicate that completely melted high-titania slags exhibit very low viscosity of around 0.8 dPa s with negligible dependence on temperature and compositions. However, it increases dramatically with decreasing temperature slightly below the critical temperature. Besides, the increase in FeO content was found to remarkably lower the critical temperature, while the addition of Ti2O3 increases it. The developed model can predict the viscosities of the TiO2-FeO-Ti2O3 and TiO2-FeO systems over wide ranges of compositions and temperatures within experimental uncertainties. The average relative error for the present model calculation is < 18.82 pct, which is better than the previously developed models for silicate slags reported in the literature. An iso-viscosity distribution diagram was made for the TiO2-FeO-Ti2O3 slag system, which can serve as a roadmap for the Ilmenite smelting reduction process as well as the high titania slags tapping process.

Hot Gas Pressure Forming of Ti-55 High Temperature Titanium Alloy Tubular Component.

In this paper, hot gas pressure forming (HGPF) of Ti-55 high temperature titanium alloy was studied. The hot deformation behavior was studied by uniaxial tensile tests at temperatures ranging from 750 to 900 °C with strain rates ranging from 0.001 to 0.05 s−1, and the microstructure evolution during tensile tests was characterized by electron backscatter diffraction. Finite element (FE) simulation of HGPF was carried out to study the effect of axial feeding on thickness distribution. Forming tests were performed to validate this process for Ti-55 alloy. Results show that when the temperature was higher than 750 °C, the elongation was large enough for HGPF of Ti-55 alloy. Dynamic recrystallization (DRX) occurred during the tensile deformation, which could refine the microstructure. The thickness uniformity of the formed part could be improved by increasing feeding length. The maximum thinning ratio decreased from 27.7% to 11.5% with the feeding length increasing from 0 to 20 mm. A qualified Ti-55 alloy component was successfully formed at 850 °C, the microstructure was slightly refined after forming, and the average post-form yield strength and peak strength were increased by 8.7% and 6.9%, respectively. Pre-heat treatment at 950 °C before HGPF could obtain Ti-55 alloy tubular component with bimodal microstructure and further improve the post-form strength.

Light emission of flame-generated TiO2 nanoparticles: Effect of IR laser irradiation

The aim of this work is the analysis of the evolution of titania nanoparticles based on their light emission spectra. Measurements are performed during the synthesis of the nanoparticles in a flame spray, which is irradiated by a pulsed IR laser. Due to the relatively high energy band gap of titania of about 3 eV, the observed substantial light absorption at the laser wavelength of 1.064 μm, i.e. within the region of titania transparency, makes our study novel and interesting.Laser-induced light emission at different laser fluences is compared with spontaneous light emission from titania nanoparticles in flame. For signal processing, Wien plot is introduced to obtain the particle temperature. A peculiar feature of the temperature difference of the irradiated and nonirradiated particles versus laser fluence is obtained. Three well-defined regions of this fluence curve are observed and discussed with a particular attention on the plateau-like behavior at very low laser fluence, followed by a linear increase. An anomalously high titania absorption is inferred in the linear region.The increase of the Urbach energy is speculated to account for the change in the optical properties of titania nanoparticles. It is related to structural defects, and, therefore, the presence of energy levels in the forbidden band due to the particular synthesis condition and/or induced by laser irradiation.

The geochemistry and Sr-Nd-Pb isotopic ratios of high 3He/4He Afar and MER basalts indicate a significant role of the African Superplume in EARS magmatism

Basaltic rocks from the Afar Depression and Main Ethiopian Rift at the northern end of the East African Rift System with 3He/4He from 6 to 17 times the atmospheric value (3He/4HeAir or RA) define two geographically and, to a lesser extent, geochemically distinct groups. These groups are inconsistent with the commonly held view that there is a distinct Afar mantle plume at the northern end of the rift system, and that the plume influence systematically decreases away from its center in Lake Abhe. The high (>9 RA) 3He/4He Afar and Ethiopian rift basaltic suites possess a common, high 3He/4He component. The ca. 30 Ma very high titanium transitional basalts and picrites from the Ethiopian-Yemeni plateau with the highest 3He/4He (ca. 20 RA) closely represent the common component. Combined with their OIB-like compositional features, the high 3He/4He basalts indicate a metasomatized or anomalous upper mantle sensu lato and African Superplume source. Similar to the mantle source of ocean island basalts, the superplume is heterogeneous as it consists of various enriched end-components with low 3He/4He (≤8 RA) and the common, depleted ‘focus zone’ component with high 3He/4He (>9 RA). Northern rift magmas are mainly pseudo-binary mixtures between the anomalous upper mantle and currently upwelling plumes from the superplume.

The Most Metal-poor Stars in the Inner Bulge*

Abstract The bulge is the oldest component of the Milky Way. Since numerous simulations of Milky Way formation have predicted that the oldest stars at a given metallicity are found on tightly bound orbits, the Galaxy’s oldest stars are likely metal-poor stars in the inner bulge with small apocenters (i.e., R apo ≲ 4 kpc). In the past, stars with these properties have been impossible to find due to extreme reddening and extinction along the line of sight to the inner bulge. We have used the mid-infrared metal-poor star selection of Schlaufman &amp; Casey (2014) on Spitzer/Galactic Legacy Infrared Mid-Plane Survey Extraordinaire data to overcome these problems and target candidate inner bulge metal-poor giants for moderate-resolution spectroscopy with Anglo-Australian Telescope/AAOmega. We used those data to select three confirmed metal-poor giants ([Fe/H] = −3.15, −2.56, −2.03) for follow-up high-resolution Magellan/Magellan Inamori Kyocera Echelle spectroscopy. A comprehensive orbit analysis using Gaia DR2 astrometry and our measured radial velocities confirms that these stars are tightly bound inner bulge stars. We determine the elemental abundances of each star and find high titanium and iron-peak abundances relative to iron in our most metal-poor star. We propose that the distinct abundance signature we detect is a product of nucleosynthesis in the Chandrasekhar-mass thermonuclear supernova of a CO white dwarf accreting from a helium star with a delay time of about 10 Myr. Even though chemical evolution is expected to occur quickly in the bulge, the intense star formation in the core of the nascent Milky Way was apparently able to produce at least one Chandrasekhar-mass thermonuclear supernova progenitor before chemical evolution advanced beyond .

Influence of TiO2 on the viscosity of the molten slag and the confirmation of the acid–base property on TiO2

ABSTRACT The viscosities of high titanium containing slag with TiO2 ranging from 23 to 43 mass%, Al2O3 9 mass% and CaO/SiO2 ranging from 0.3 to 0.7 were experimentally determined by the rotating cylinder method. Experiments were conducted in the temperature range of 1573–1873 K. The effects of TiO2, basicity, and temperature on viscosity were studied. The experimental results indicated that above the liquidus temperatures, the viscosities decrease with TiO2 and basicity increasing. And increasing on CaO content should be more effective in depolymerizing slag structure and lowering viscosity compared to TiO2 addition. Moreover TiO2 behaved as a weak acid oxide in the experiment slags by XPS analysis. Based on the experimental data of CaO–SiO2–Al2O3–TiO2 quaternary system, the activation energy of viscous flow was calculated between 115 and 141 kJ mol−1 depending on the slag composition.

Effect of Impact Toughness Anisotropy on Brittle Fracture Resistance Characteristics of High-Strength Steels Subjected to Thermomechanical Treatment

The structure and mechanical properties under tension and impact bending of eleven batches of high-strength manganese-containing steels (Mn-steels) containing 0.09 to 0.14 wt.% Ti subjected to thermomechanical rolling were studied in the temperature range from –60 to +20 °С. It was found that the values of the coefficient of impact toughness anisotropy in the range of Ka = 2.0–4.9 increase at higher titanium content and decrease at higher aluminum content. The difference between ductile-to-brittle transition temperatures T50 and T34 for longitudinal and transverse KCV samples increases at higher contents of titanium, aluminum, sulfur, and carbon. This effect is caused by an earlier nucleation and growth of large dimples of ductile fracture around sizable inclusions preferentially located in the direction of rolling.

Raman Fingerprint of Pressure-Induced Phase Transitions in TiS3 Nanoribbons: Implications for Thermal Measurements under Extreme Stress Conditions

Two-dimensional layered trichalcogenide materials have recently attracted the attention of the scientific community because of its robust mechanical, thermal properties and applications in opto and nanoelectronics devices. We report the pressure dependence of out-of plane Ag Raman modes in high quality few-layers titanium trisulfide (TiS3) nanoribbons grown using a direct solid-gas reaction method and infer their cross-plane thermal expansion coefficient.Both mechanical stability and thermal properties of the TiS3 nanoribbons are elucidated using phonon-spectrum analyses. Raman spectroscopic studies at high pressure (up to 34 GPa) using a diamond anvil cell identify four prominent Ag Raman bands; a band at 557 cm-1 softens under compression, and others at 175, 300, and 370 cm-1 show normal hardening. Anomalies in phonon mode frequencies and excessive broadening in line-width of the soft phonon about ~ 13 GPa are attributed to the possible onset of a reversible structural transition. A complete structural phase transition at 43 GPa is inferred from Ag soft mode frequency (557 cm-1) versus pressure extrapolation curve, consistent with recent reported theoretical predictions. Using the experimental mode Gr\"uneisen parameters i of Raman modes, the cross-plane thermal expansion coefficient Cv of the TiS3 nanoribbons at ambient phase is estimated to be1.32110-6K-1. The observed results are expected to be useful in calibration and performance of next generation nano-electronics and optical devices under extreme stress conditions.

Stress-based fatigue behavior of Ti–6Al–4V alloy with a discontinuous lamellar microstructure fabricated by thermomechanical powder consolidation

A powder metallurgy (PM) Ti–6Al–4V alloy with a novel discontinuous lamellar microstructure and a high relative density was fabricated by thermomechanical powder consolidation (TMC) of TiH2–Al60V40 powder and subsequent heat treatment. It was found that the PM Ti–6Al–4V alloy exhibited a high fatigue performance relative to that of the Ti–6Al–4V alloy fabricated using the traditional powder metallurgy process of pressing and sintering. The fatigue cracks initiated at grain boundary α phase along the near-basal planes instead of pores due to their small sizes. The TMC defects enlarged and induced secondary cracks under low-stress cyclic loading, leading to stress redistribution at the crack tip. The discontinuous lamellar microstructure caused an increase of fatigue crack deflection frequency and easier crack closure relative to the fully-lamellar microstructure, owing to the increase of the number density of the α/β interfaces and the random distribution of the crystallographic orientations of the fine domains of α/β lamellar structure. The high plasticity of the crack tip makes the crack blunt due to the strain mismatch between the α and β phases of the discontinuous lamellar microstructure. Consequently, the factors associated with microstructures and defects for limiting the fatigue performance of powder metallurgy titanium alloys were identified, and a meaningful route to enhance the fatigue properties was proposed for fabrication of low cost and high performance PM titanium alloys.

High-Temperature Deformation Behavior and Microstructural Characterization of Ti-35421 Titanium Alloy.

A self-designed Ti-35421 (Ti-3Al-5Mo-4Cr-2Zr-1Fe wt%) titanium alloy is a new type of low-cost high strength titanium alloy. In order to understand the hot deformation behavior of Ti-35421 alloy, isothermal compression tests were carried out under a deformation temperature range of 750–930 °C with a strain rate range of 0.01–10 s−1 in this study. Electron backscatter diffraction (EBSD) was used to characterize the microstructure prior to and post hot deformation. The results show that the stress–strain curves have obvious yielding behavior at a high strain rate (>0.1 s−1). As the deformation temperature increases and the strain rate decreases, the α phase content gradually decreases in the α + β phase region. Meanwhile, spheroidization and precipitation of α phase are prone to occur in the α + β phase region. From the EBSD analysis, the volume fraction of recrystallized grains was very low, so dynamic recovery (DRV) is the dominant deformation mechanism of Ti-35421 alloy. In addition to DRV, Ti-35421 alloy is more likely to occur in continuous dynamic recrystallization (CDRX) than discontinuous dynamic recrystallization (DDRX).

Bacteria Remediate the Effects of Food Additives on Intestinal Function in an in vitro Model of the Gastrointestinal Tract.

As the site of nutrient absorption, the small intestine is continuously exposed to preservatives and additives present in consumed food. While the effects of diet on the lower gastrointestinal tract are widely studied, the effects of food additives on the small intestinal epithelium and microbiota are less clearly understood. The goal of this work was to develop and establish a physiologically relevant model of the upper gastrointestinal tract to study the complex interactions between food additives, individual bacterial species, and intestinal function. To achieve this, an in vitro model incorporating simulated digestion, human intestinal epithelial cells, and the commensal, Gram-positive Lactobacillus rhamnosus, or the opportunistic, Gram-negative Escherichia coli was developed. This model was used to assess intestinal permeability and alkaline phosphatase activity following exposure to high glucose (HG), salt, emulsifier (TWEEN 20), food (milk chocolate candies) or chemical grade titanium dioxide nanoparticles (TiO2-NP), and food (whole wheat bread) or chemical grade gluten. It was found that HG increased intestinal permeability, the presence of bacteria remediated the negative effects of HG on intestinal permeability, and a decrease in permeability and IAP activity was observed with increasing concentration of TWEEN 20 both in the presence and absence of bacteria. While L. rhamnosus influenced the activity of intestinal alkaline phosphatase and tight junction protein distribution, E. coli produced indole to reinstate intestinal permeability. The source of TiO2 and gluten led to altered impacts on permeability and IAP activity. The growth of E. coli and L. rhamnosus was found to depend on the type of food additive used. Overall, the presence of bacteria in the in vitro model influenced the effects of food additives on intestinal function, suggesting a complex association between diet and upper GI microbiota. This model provides a method to study small intestinal function and host-microbe interactions in vitro in both healthy and diseased conditions.

Effects of BaO on the Viscosity and Structure of a New Fluorine-Free CaO-Al2O3-TiO2-Based Mold Flux for High Titanium Steel

Herein, the effects of BaO (i.e. 5, 10, 15 and 20 pct) on the viscosity and structures of a new fluorine-free CaO-Al2O3-TiO2-based mold flux with w(CaO pct)/w(Al2O3 pct) ratio of 1.0 are investigated using a rotary viscometer, molecular dynamics (MD) simulations, and Raman spectroscopy. The viscosity of the samples (the testing temperature is 1300 °C) decrease from 0.46 to 0.21 Pa·s as the BaO content increased from 5 to 20 pct, and the activation energy decreases from 150.7 to 119.7 kJ·mol−1, the break temperature (Tbr) decreases from 1475 K to 1429 K which are achieved as the initial testing temperature of 1300 °C decreased under the furnace cooling. With the addition of BaO, the MD simulation results suggest that the coordination numbers (CNs) of Al (Ti)-O are reduced, while Q3, Q4, and Q5 are depolymerized into Q0, Q1, and Q2. The Raman spectroscopy results illustrate that the bridge oxygens (BOs) originating from the Ti-O-Ti (Al) linkages and Q2 (Al-O−) are depolymerized into Q1 (Si-O−) and Q0 (Al-O−) as the BaO content is increased. The Raman spectroscopy results agree well with those of the MD simulation. Therefore, BaO can simplify the structure of melts and decrease the viscosity of such systems. This work not only presents a new fluorine-free CaO-Al2O3-TiO2-based mold flux, but also deepens the understandings of the role of BaO in this system.

Isoprene polymerizations catalyzed by TiCl4/MgCl2 type Ziegler-Natta catalysts with different titanium contents

The isoprene polymerization kinetics by using TiCl4/MgCl2 type Ziegler-Natta catalysts (TMC) with different titanium contents were studied for better understanding the possible active-specie structures of heterogeneous Ziegler-Natta (Z-N) catalysts for conjugated diene polymerizations. The catalytic features including the catalytic activity (CA), number of active centers ([C*]/[Ti]), rate constant for polymerization (kp), stereoregularity of these TMC catalysts were studied. The low titanium content catalyst TMC-1 (Ti = 0.09 wt.%) with more isolated mononuclear titanium species showed higher CA and yielded cis-1,4-/trans-1,4- mixed microstructure polyisoprene with low molecular weight (Mw) in the initial polymerization stage. The medium high titanium content catalyst TMC-2 (Ti = 2.38 wt.%) with more clustered mononuclear titanium species showed lower CA and yielded cis-1,4-/trans-1,4- mixed microstructure polyisoprene with high Mw in the early stage of polymerization. The high titanium content catalyst TMC-3 (Ti = 3.76 wt.%) presented lowest CA and yielded high trans-1,4- polyisoprene with higher Mw.

Formation of intermediate phases and their influences on the microstructure of high strength near-β titanium alloy

The influences of heating rate to aging temperature on intermediate phase transformation and final microstructures of near βTi alloy Ti–5Al–3Mo–3V–2Cr–2Zr–1Nb–1Fe (wt.%) have been studied in this work. The results showed that three nano-scaled intermediate phases, i. e. O′, ωiso and O″ phases, were subsequently formed before α precipitation when heating by slow (10 °C/min) and fast (~100 °C/min) rates, depending on heating rate. The ωiso and O″ phases become unstable and will dissolve before arriving the aging temperature, while plenty of O′ domains can always be observed accompanying with the precipitation of needle-like α phase. Whereas upon rapid heating (~400 °C/min), only O′ phase can be observed during continuous heating to target aging temperature. We suggest that the uniform and dense distribution of fine α precipitates formed even at fast heating rate ascribes for the precipitation of a large number of O′ precursors assist α nucleation. The slow and fast heating rates result in similar yield strength of the aged samples, however, the slow heating rate can obtain better ductility due to the formation of discontinuous grain boundary α colonies instead of continuous α layers.

The effect of T-atom ratio and TPAOH concentration on the pore structure and titanium position in MFI-Type titanosilicate during dissolution-recrystallization process

In this work, titanosilicate MFI (TS-1) crystals with different Si/Ti ratio were treated with tetrapropylamonium hydroxide (TPAOH) solution of different concentrations. The results showed that the properties – crystal structure, titanium position, secondary pore structure and volume – of the treated samples strongly depend on the Si/Ti ratio of the parent TS-1 sample and the TPAOH concentration. For instance, high TPAOH concentration is necessary to induce titanium re-insertion into framework position and to create inter-connected open meso/macropore in TS-1 with low Si/Ti ratio. On the contrary, TPAOH treatment even at high concentration was found to be ineffective in the post-synthesis treatment of low titanium containing TS-1 samples and result in a phase change from orthorhombic to monoclinic. The post-treated high titanium containing and inter-connected secondary pore TS-1 samples exhibited higher activity for cyclohexene epoxidation than the parent TS-1 sample with similar Si/Ti. This technique provides a controlled way of mesopore creation in TS-1 materials, which may be extended to other titanium base microporous materials.

High Temperature Reduced Granulite-Facies Nature of Garnetites in the Khabarny Mafic–Ultramafic Massif, Southern Urals: Evidence from Fluid and Mineral Analyses

Abstract High-grade metamorphic rocks underlying the intrusive layered dunite–pyroxenite–gabbronorite East-Khabarny Complex (EKC) are integrated in the complex Khabarny mafic–ultramafic Massif in the Sakmara Allochthon zone in the Southern Urals. These rocks are associated with high-temperature shear zones. Garnetites from the upper part of the metamorphic unit close to the contact with EKC gabbronorite are chemically and texturally analysed to estimate their formation conditions and fluid regime. Fluids provide crucial information of formation conditions and evolution of these garnetites during high-grade metamorphism, and are preserved in channel positions within Si6O1812- rings of cordierite, and in fluid inclusions in quartz and garnet. Minerals and fluid inclusions of the garnetites are studied with X-ray fluorescence spectrometry, electron microprobe analyses, Raman spectroscopy, and microthermometry. The garnetites mainly consist of garnet (up to 80 vol. %), cordierite and quartz. Accessory minerals are rutile, ilmenite, graphite, magnetite and cristobalite. Granulite-facies metamorphic conditions of the garnetites are estimated with the garnet–cordierite–sillimanite–quartz geothermobarometer: temperatures of 740 to 830 ˚C and pressures of 770–845 MPa. The average garnet composition in end-member concentrations is 48·5 mole % almandine (±3·9), 34·7 mole % pyrope (±3·3), 10·3 mole % spessartine (±1·1), 1·8 mole % grossular (±1·5), and 1·5 mole % andradite (±1·5). The cordierite electron microprobe analyses reveal an average Mg2+ fraction of 0·79 ± 0·01 in the octahedral site. Relicts of a strong positive temperature anomaly (up to 1000 ˚C) are evidenced by the preservation of cristobalite crystals in garnet and the high titanium content of quartz (0·031 ± 0·008 mass % TiO2) and garnet (0·31 ± 0·16 mole % end-member Schorlomite-Al). The fluid components H2O, CO2, N2 and H2S are detected in cordierite, which correspond to a relatively oxidized fluid environment that is common in granulites. In contrast, a highly reduced fluid environment is preserved in fluid inclusions in quartz nodules, which are mono-fluid phase at room temperature and composed of CH4 (&amp;gt;96 mole %) with locally minor amounts of C2H6, N2, H2S and graphite. The fluid inclusions occur in homogeneous assemblages with a density of 0·349 to 0·367 g·cm-3. The CH4-rich fluid may represent peak-temperature metamorphic conditions, and is consistent with temperature estimation (∼1000 ˚C) from Ti-in-garnet and Ti-in-quartz geothermometry. Tiny CH4-rich fluid inclusions (diameter 0·5 to 2 µm) are also detected by careful optical analyses in garnet and at the surface of quartz crystals that are included in garnet grains. Graphite in fluid inclusions precipitated at retrograde metamorphic conditions around 300–310 ± 27 ˚C. Aragonite was trapped simultaneously with CH4-rich fluids and is assumed to have crystallized at metastable conditions. The initial granulite facies conditions that led to the formation of a cordierite and garnet mineral assemblage must have occurred in a relative oxidized environment (QFM-buffered) with H2O–CO2-rich fluids. Abundant intrusions or tectonic emplacement of mafic to ultramafic melts from the upper mantle that were internally buffered at a WI-buffered (wüstite–iron) level must have released abundant hot CH4-rich fluids that flooded and subsequently dominated the system. The origin of the granulite-facies conditions is similar to peak-metamorphic conditions in the Salda complex (Central Urals) and the Ivrea–Verbano zone (Italian Alps) as a result of magmatic underplating that provided an appearance of a positive thermal anomaly, and further joint emplacement (magmatic and metamorphic rocks together) into upper crustal level as a high temperature plastic body (diapir).

Thermal conductance at nanoscale amorphous boron nitride/metal interfaces

To combat the ever-increasing challenge of thermal management in nanoelectronic devices and reduce the risk of overheating during operation, material interfaces near the active region of a device must be designed for efficient thermal transport. In this study, metal contacts on amorphous boron nitride (a-BN) thin films, a promising dielectric material in two-dimensional systems, are evaluated for the relative thermal transport efficiency. Metals with small atomic masses and high Debye temperatures, aluminum and titanium, reveal as much as a six times improvement in interface thermal conductance, as measured by time domain thermoreflectance, compared to metals of larger atomic masses and low Debye temperatures such as gold and tantalum. The interface transport between a-BN and higher Debye temperature metals prove to depend on the growth conditions, and good initial film wettability was crucial for ensuring a quality metal contact. Interfacial bonding was evaluated by x-ray photoelectronic spectroscopy and the impact on a-BN chemistry and oxidation potential contributed to the understanding of phonon transport across the interface. The study described herein reinforces the crucial requirement to design effective thermal contacts in high-power electronic devices where Joule heating is a concern.

Microstructure and texture variations in high temperature titanium alloy Ti65 sheets with different rolling modes and heat treatments.

Ti65 alloy (Ti-5.8Al-4.0Sn-3.5Zr-0.5Mo-0.4Si-0.3Nb-1.0Ta-0.8W-0.05C) is the newly developed high temperature titanium alloy optimized from Ti60 alloys. The long-term service temperature of the alloy is as high as 650 °C, which is unattainable with the previous high temperature titanium alloy. It has excellent strength and excellent creep resistance, and has great application prospects in the aerospace industry. In the current study, the evolution of microstructure and texture of Ti65 alloy sheets developed by unidirectional rolling (UDR) and cross rolling (CR) followed by solution and aging treatment was investigated. The microstructure of the UDR sample consists of equiaxed , lamellar and few elongated , and the texture is the combination of minor B-type and major T-type texture, with the main component of basal {0001} fiber texture and , respectively. Due to more active slip system resulted by transformed direction, the microstructure of the CR sample consists of more elongated , and the <0001> texture characterized as R-type texture forms in addition to B/T-type texture. With aging temperature increasing, the microstructures for both transform to duplex microstructure, and the thicknesses of lamellar increase. B-type texture becomes stronger, while T/R-type texture are weakened, which is caused by the combination of recrystallization, spheroidization, and variant selection. An abnormal increasing of T/R-type texture but constant B-type texture happens in the CR-600 sample, which is related to high recrystallization fraction. It is expected that the research results can provide useful references for the rolling of high temperature titanium alloy sheets and the precise control of microstructure/texture.

Effect of titanium suboxide on the formation of anatase and rutile phases during annealing of C-Doped Ti–O thin film deposited by DC magnetron sputtering

C-doped Ti–O films with different titanium suboxide contents are prepared by DC magnetron sputtering deposition at different sputtering powers. The films with different phases are formed after annealing at 873[Formula: see text]K in air. The structure of the films is characterized by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The optical properties and surface roughness of the films are investigated by UV–vis spectroscopy and atomic force microscopy, respectively. Photocatalytic activity of the thin films is studied by degrading the methyl orange solution under xenon lamp (300[Formula: see text]W) irradiation. The results show that the C-doped Ti–O thin films with higher titanium suboxide contents ([Formula: see text]%) tend to form the rutile phase after annealing, whereas the films with a lower titanate content ([Formula: see text]%) are easy to form anatase phase by annealing.