Sample records for vanadium alloy structure

  1. Electronic structure of lead telluride-based alloys, doped with vanadium

    NASA Astrophysics Data System (ADS)

    Skipetrov, E. P.; Golovanov, A. N.; Slynko, E. I.; Slynko, V. E.

    2013-01-01

    The crystal structure, composition, galvanomagnetic properties in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T), and the Shubnikov-de Haas effect (T = 4.2 K, B ≤ 7 T) are studied in Pb1-x-ySnxVyTe (x = 0, 0.05-0.18) alloys synthesized by the Bridgman technique with variable vanadium impurity concentrations. It is shown that increasing the vanadium content leads to the formation of regions enriched in vanadium and of microscopic inclusions of compounds with compositions close to V3Te4. In Pb1-yVyTe stabilization of the Fermi level by a deep vanadium level, an insulator-metal transition, and a rise in the free electron concentration are observed as the vanadium content is increased. The variation in the free charge carrier concentration with increasing vanadium concentration in Pb1-yVyTe and Pb1-x-ySnxVyTe (x = 0.05-0.18) alloys is compared. Possible models for rearrangement of the electronic structure in Pb1-x-ySnxVyTe alloys with vanadium doping are discussed.

  2. VANADIUM ALLOYS

    DOEpatents

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  3. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  4. Recent progress on gas tungsten arc welding of vanadium alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    King, J.F.; Grossbeck, M.L.; Goodwin, G.M.

    1997-04-01

    This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that themore » atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates.« less

  5. THE COLORIMETRIC DETERMINATION OF VANADIUM IN NIOBIUM-VANADIUM ALLOYS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Articolo, O.J.

    1959-06-26

    A procedure is described for the analysis of vanadium in niobium-- vanadium alloys in the range >0.1% vanadium with an accuracy of better than 3%. The method was applied to the analysis of niobium alloys in which the nominal per cent vanadium varied between 0.3 to 4.6%. The sample is dissolved in a mixture of nitric and hydrofluoric acid and then evaporated to fumes with sulfuric acid. The niobium is hydrolyzed with sulfurous acid and separated from the vanadium by filtration. Hydrogen peroxide is added to the filtrate to form a reddish brown complex with the vanadium. The optical densitymore » of the resulting solution is obtained at 450 m mu on a model B Beckman spectrophotometer. (auth)« less

  6. Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

    NASA Astrophysics Data System (ADS)

    Nechaykina, Tatyana A.; Nikulin, Sergey A.; Rozhnov, Andrey B.; Khatkevich, Vladimir M.; Rogachev, Stanislav O.

    2017-03-01

    The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of "transition" area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22- µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

  7. A vanadium alloy for the application in a liquid metal blanket of a fusion reactor

    NASA Astrophysics Data System (ADS)

    Borgstedt, H. U.; Grundmann, M.; Konys, J.; Perić, Z.

    1988-07-01

    The vanadium alloy V3Ti1Si has been corrosion tested in liquid lithium and the eutectic alloy Pb-17Li at 550°C. This alloy has a comparable corrosion resistance to the alloy V15Cr5Ti in lithium. In this molten metal it is superior to stainless steel AISI 316. In the Pb-17Li melt it is even superior to martensitic steels. The alloy has only a weak tendency to be dissolved. It is sensitive to an exchange of non-metallic elements, which causes the formation of a hardened surface layer. These chemical effects are influenced by the mass and surface ratios of the vanadium alloy to the molten metals and other structural materials. These ratios are unfavorable in the two test loops. The effects might be less pronounced in a vanadium alloy/liquid metal fusion reactor blanket.

  8. Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1975-01-01

    Tensile and creep properties of experimental beta-titanium alloys were determined. Titanium-vanadium alloys had substantially greater tensile and creep strength than the titanium-niobium and titanium-molybdenum alloys tested. Specific tensile strengths of several titanium-vanadium-aluminum-silicon alloys were equivalent or superior to those of commercial titanium alloys to temperatures of 650 C. The Ti-50V-3Al-1Si alloy had the best balance of tensile strength, creep strength, and metallurgical stability. Its 500 C creep strength was far superior to that of a widely used commercial titanium alloy, Ti-6Al-4V, and almost equivalent to that of newly developed commercial titanium alloys.

  9. Proving the viability of manufacturing of multi-layer steel/vanadium alloy/steel composite tubes by numerical simulations and experiment

    NASA Astrophysics Data System (ADS)

    Nechaykina, T.; Nikulin, S.; Rozhnov, A.; Molotnikov, A.; Zavodchikov, S.; Estrin, Y.

    2018-05-01

    Vanadium alloys are promising structural materials for fuel cladding tubes for fast-neutron reactors. However, high solubility of oxygen and nitrogen in vanadium alloys at operating temperatures of 700 °C limits their application. In this work, we present a novel composite structure consisting of vanadium alloy V-4Ti-4Cr (provides high long-term strength of the material) and stainless steel Fe-0.2C-13Cr (as a corrosion resistant protective layer). It is produced by co-extrusion of these materials forming a three-layered tube. Finite element simulations were utilised to explore the influence of the various co-extrusion parameters on manufacturability of multi-layered tubes. Experimental verification of the numerical modelling was performed using co-extrusion with the process parameters suggested by the numerical simulations. Scanning electron microscopy and microhardness measurements revealed a defect-free diffusion layer at the interfaces between both materials indicating a good quality bonding for these co-extrusion conditions.

  10. TEM investigation of ductile iron alloyed with vanadium.

    PubMed

    Dymek, S; Blicharski, M; Morgiel, J; Fraś, E

    2010-03-01

    This article presents results of the processing and microstructure evolution of ductile cast iron, modified by an addition of vanadium. The ductile iron was austenitized closed to the solidus (1095 degrees C) for 100 h, cooled down to 640 degrees C and held on at this temperature for 16 h. The heat treatment led to the dissolution of primary vanadium-rich carbides and their subsequent re-precipitation in a more dispersed form. The result of mechanical tests indicated that addition of vanadium and an appropriate heat treatment makes age hardening of ductile iron feasible. The precipitation processes as well as the effect of Si content on the alloy microstructure were examined by scanning and transmission electron microscopy. It was shown that adjacent to uniformly spread out vanadium-rich carbides with an average size of 50 nm, a dispersoid composed of extremely small approximately 1 nm precipitates was also revealed.

  11. Effect of Vanadium and Sodium Compounds on Accelerated Oxidation of Nickel-Base Alloys.

    DTIC Science & Technology

    The product of the reaction between V2O5 and the substrates is dependent upon the alloying elements present in the alloy. In the absence of alloying...reaction appears to be a glass . The study is related to corrosion inhibitions in vanadium containing fuels in gas turbines. (Modified author abstract)

  12. Fusion materials: Technical evaluation of the technology of vandium alloys for use as blanket structural materials in fusion power systems

    NASA Astrophysics Data System (ADS)

    1993-08-01

    The Committee's evaluation of vanadium alloys as a structural material for fusion reactors was constrained by limited data and time. The design of the International Thermonuclear Experimental Reactor is still in the concept stage, so meaningful design requirements were not available. The data on the effect of environment and irradiation on vanadium alloys were sparse, and interpolation of these data were made to select the V-5Cr-5Ti alloy. With an aggressive, fully funded program it is possible to qualify a vanadium alloy as the principal structural material for the ITER blanket in the available 5 to 8-year window. However, the data base for V-5Cr-5Ti is limited and will require an extensive development and test program. Because of the chemical reactivity of vanadium the alloy will be less tolerant of system failures, accidents, and off-normal events than most other candidate blanket structural materials and will require more careful handling during fabrication of hardware. Because of the cost of the material more stringent requirements on processes, and minimal historical working experience, it will cost an order of magnitude to qualify a vanadium alloy for ITER blanket structures than other candidate materials. The use of vanadium is difficult and uncertain; therefore, other options should be explored more thoroughly before a final selection of vanadium is confirmed. The Committee views the risk as being too high to rely solely on vanadium alloys. In viewing the state and nature of the design of the ITER blanket as presented to the Committee, it is obvious that there is a need to move toward integrating fabrication, welding, and materials engineers into the ITER design team. If the vanadium alloy option is to be pursued, a large program needs to be started immediately. The commitment of funding and other resources needs to be firm and consistent with a realistic program plan.

  13. Vanadium release in whole blood, serum and urine of patients implanted with a titanium alloy hip prosthesis.

    PubMed

    Catalani, S; Stea, S; Beraudi, A; Gilberti, M E; Bordini, B; Toni, A; Apostoli, P

    2013-08-01

    Vanadium (V) is a minor constituent of the Titanium-Aluminum-Vanadium (TiAlV) alloy currently used in cementless hip prostheses. Present study aimed at verifying the correlation of vanadium levels among different matrices and assessing reference levels of the ion in a population of patients wearing a well-functioning hip prosthesis. Vanadium was measured using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) in whole blood, serum and urine of 129 patients implanted with a TiAlV-alloy hip prosthesis. The values in the serum were above the upper limit of the reference values in 42% of patients (29% in urine and 13% in whole blood). A good correlation among matrices was observed (p < 0.001). The cohort of patients (N = 32) complaining of pain or in which a loosening or damage to the prosthesis was assessed showed a significantly higher excretion of vanadium in urine as compared with the remaining asymptomatic patients (p = 0.001). The 95th percentile distribution of vanadium in the cohort of patients with a well-functioning prosthesis was 0.3 μg/L in whole blood, 0.5 μg/L in serum and 2.8 μg/L in urine, higher that in the unexposed population, especially for urine. The presence of a prosthesis, even though well-functioning, may cause a possible release of vanadium into the blood and a significant urinary excretion. The reference values of vanadium of the asymptomatic patients with titanium alloy hip prostheses supplied information regarding the background exposure level of the ions and their lower and upper limits.

  14. Corrosion resistance investigation of vanadium alloys in liquid lithium

    NASA Astrophysics Data System (ADS)

    Borovitskaya, I. V.; Lyublinskiy, I. E.; Bondarenko, G. G.; Paramonova, V. V.; Korshunov, S. N.; Mansurova, A. N.; Lyakhovitskiy, M. M.; Zharkov, M. Yu.

    2016-12-01

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10-3 wt %) of vanadium and vanadium alloys (V-1.86Ga, V-3.4Ga-0.62Si, V-4.81Ti-4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 1022 m-2 at an irradiation temperature of 400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  15. Blistering behavior and deuterium retention in tungsten vanadium alloys exposed to deuterium plasma in the linear plasma device STEP

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Cheng, Long; Yuan, Yue; Qin, Shao-Yang; Arshad, Kameel; Guo, Wang-Guo; Wang, Zheng; Zhou, Zhang-Jian; Lu, Guang-Hong

    2018-03-01

    The behavior of tungsten-vanadium (W-V) alloys fabricated by powder metallurgy as a plasma facing material has been studied. W-V alloys with different vanadium concentrations (5 and 10 wt %) manufactured by hot pressing (HP) were exposed to deuterium plasma (flux ∼4.6 × 1021 m-2s-1, fluence ∼5.6 × 1025 m-2, ion energy ∼60 eV, target temperature ∼450 K) in the linear plasma device STEP at Beihang University. Three typical grains are observed on HP sintered W-V alloys and exhibit a significant effect on its performance under deuterium plasma irradiation. Surface blistering only occurs at W-enriched grains and is significantly mitigated in W-V alloys, especially in W-10 V, blistering is completely suppressed. On the other hand, deuterium retention dramatically increases in the W-V alloys due to vanadium addition. The deuterium retention in W-5 wt. % V is about 6.2 times more than that in rolled pure W, and this factor further increases to 6.9 when the V concentration rises to 10 wt %. We ascribe these phenomena to the changes of microstructures and components caused by vanadium addition.

  16. Corrosion resistance investigation of vanadium alloys in liquid lithium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borovitskaya, I. V., E-mail: symp@imet.ac.ru; Lyublinskiy, I. E.; Bondarenko, G. G.

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10{sup –3} wt %) of vanadium and vanadium alloys (V–1.86Ga, V–3.4Ga–0.62Si, V–4.81Ti–4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 10{sup 22} m{sup –2} at an irradiation temperature of ~400°C. The degree of corrosion was estimated by measuring the changesmore » in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.« less

  17. Method for preparing high purity vanadium

    DOEpatents

    Schmidt, Frederick; Carlson, O. Norman

    1986-09-09

    A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

  18. Method for preparing high purity vanadium

    DOEpatents

    Schmidt, F.; Carlson, O.N.

    1984-05-16

    A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

  19. Effect of hydrogen on fatigue crack propagation in vanadium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chung, D.W.; Stoloff, N.S.

    The influence of hydrogen on fatigue crack propagation in unalloyed vanadium and several hydrogen-charged vanadium alloys has been investigated. The Paris--Erdogan equation, da/dN = C(..delta..K)/sup m/, was approximately obeyed for all alloys. Crack growth rates were lowest in vanadium and dilute vanadium-hydrogen alloys, and were not very sensitive to volume fraction of hydrides in more concentrated alloys. The crack growth exponent, m, is inversely proportional to the cyclic strain hardening rate, n', and the rate constant C is inversely proportional to the square of the ultimate tensile stress, sigma/sub UTS/: metallographic examination showed hydride reorientation and growth in the originallymore » hydrided alloys. No stress-induced hydrides were observed in V-H solid-solution alloys. Fractures in hydrided materials exhibited cleavage-like features, while striations were noted in unalloyed vanadium and dilute solid-solution alloys.« less

  20. Effect of hydrogen on fatigue crack propagation in vanadium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chung, D.W.; Stoloff, N.S.

    The influence of hydrogen on fatigue crack propagation in unalloyed vanadium and several hydrogen-charged vanadium alloys has been investigated. The Paris--Erdogan equation, da/dN = C(..delta..K)/sup m/, was approximately obeyed for all alloys. Crack growth rates were lowest in vanadium and dilute vanadium--hydrogen alloys, and were not very sensitive to volume fraction of hydrides in more concentrated alloys. The crack growth exponent, m, is inversely proportional to the cyclic strain hardening rate, n', and the rate constant C is inversely proportional to the square of the ultimate tensile stress, sigma/sub UTS/: metallographic examination showed hydride reorientation and growth in the originallymore » hydrided alloys. No stress-induced hydrides were observed in V--H solid-solution alloys. Fractures in hydrided materials exhibited cleavage-like features, while striations were noted in unalloyed vanadium and dilute solid-solution alloys.« less

  1. Vanadium Oxide Thin Films Alloyed with Ti, Zr, Nb, and Mo for Uncooled Infrared Imaging Applications

    NASA Astrophysics Data System (ADS)

    Ozcelik, Adem; Cabarcos, Orlando; Allara, David L.; Horn, Mark W.

    2013-05-01

    Microbolometer-grade vanadium oxide (VO x ) thin films with 1.3 < x < 2.0 were prepared by pulsed direct-current (DC) sputtering using substrate bias in a controlled oxygen and argon environment. These films were systematically alloyed with Ti, Nb, Mo, and Zr using a second gun and radiofrequency (RF) reactive co-sputtering to probe the effects of the transition metals on the film charge transport characteristics. The results reveal that the temperature coefficient of resistance (TCR) and resistivity are unexpectedly similar for alloyed and unalloyed films up to alloy compositions in the ˜20 at.% range. Analysis of the film structures for the case of the 17% Nb-alloyed film by glancing-angle x-ray diffraction and transmission electron microscopy shows that the microstructure remains even with the addition of high concentrations of alloy metal, demonstrating the robust character of the VO x films to maintain favorable electrical transport properties for bolometer applications. Postdeposition thermal annealing of the alloyed VO x films further reveals improvement of electrical properties compared with unalloyed films, indicating a direction for further improvements in the materials.

  2. Vanadium recycling in the United States in 2004

    USGS Publications Warehouse

    Goonan, Thomas G.

    2011-01-01

    As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

  3. Allergic reaction to vanadium causes a diffuse eczematous eruption and titanium alloy orthopedic implant failure.

    PubMed

    Engelhart, Sally; Segal, Robert J

    2017-04-01

    Allergy as a cause of adverse outcomes in patients with implanted orthopedic hardware is controversial. Allergy to titanium-based implants has not been well researched, as titanium is traditionally thought to be inert. We highlight the case of a patient who developed systemic dermatitis and implant failure after surgical placement of a titanium alloy (Ti6Al4V) plate in the left foot. The hardware was removed and the eruption cleared in the following weeks. The plate and screws were submitted for metal analysis. The elemental composition of both the plate and screws included 3 major elements-titanium, aluminum, and vanadium-as well as trace elements. Metal analysis revealed that the plate and screws had different microstructures, and electrochemical studies demonstrated that galvanic corrosion could have occurred between the plate and screws due to their different microstructures, contributing to the release of vanadium in vivo. The patient was patch tested with several metals including components of the implant and had a positive patch test reaction only to vanadium trichloride. These findings support a diagnosis of vanadium allergy and suggests that clinicians should consider including vanadium when patch testing patients with a suspected allergic reaction to vanadium-containing implants.

  4. Formation Energies and Electronic Properties of Vanadium Carbides Found in High Strength Steel Alloys

    NASA Astrophysics Data System (ADS)

    Limmer, Krista; Medvedeva, Julia

    2013-03-01

    Carbide formation and stabilization in steels is of great interest owing to its effect on the microstructure and properties of the Fe-based alloys. The appearance of carbides with different metal/C ratios strongly depends on the carbon concentration, alloy composition as well as the heat treatment. Strong carbide-forming elements such as Ti, V, and Nb have been used in microalloyed steels; with VC showing an increased solubility in the iron matrix as compared with TiC and NbC. This allows for dissolution of the VC into the steel during heating and fine precipitation during cooling. In addition to VC, the primary vanadium carbide with cubic structure, a wide range of non-stoichiometric compositions VCy with y varying from 0.72 to 0.88, has been observed. This range includes two ordered compounds, V8C7 and V6C5. In this study, first-principles density functional theory (DFT) is employed to examine the stability of the binary carbides by calculating their formation energies. We compare the local structures (atomic coordination, bond distances and angles) and the density of states in optimized geometries of the carbides. Further, the effect of alloying additions, such as niobium and titanium, on the carbide stabilization is investigated. We determine the energetically preferable substitutional atom location in each carbide and study the impurity distribution as well as its role in the carbide formation energy and electronic structure.

  5. Effects of irradiation to 4 dpa at 390 C on the fracture toughness of vanadium alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gruber, E.E.; Galvin, T.M.; Chopra, O.K.

    Fracture toughness J-R curve tests were conducted at room temperature on disk-shaped compact-tension DC(T) specimens of three vanadium alloys having a nominal composition of V-4Cr-4Ti. The alloys in the nonirradiated condition showed high fracture toughness; J{sub IC} could not be determined but is expected to be above 600 kJ/m{sup 2}. The alloys showed very poor fracture toughness after irradiation to 4 dpa at 390 C, e.g., J{sub IC} values of {approx}10 kJ/m{sup 2} or lower.

  6. Features of radiation damage of vanadium and its alloys at a temperature of 330-340°C

    NASA Astrophysics Data System (ADS)

    Kazakov, V. A.; Ostrovsky, Z.; Goncharenko, Yu; Chakin, V.

    2000-12-01

    Microstructural changes of vanadium alloys after irradiation at 340°C to 12 dpa in the BOR-60 reactor in 7Li environment is analyzed. Materials are vanadium and its alloys V-3Ti, V-3Fe, V-6Cr, V-4Cr-4Ti, V-5Cr-10Ti, V-6Cr-1Zr-0.1C. Void formation was observed in the binary alloys V-3Fe, V-3Ti and V-6Cr. It is shown that three-four-fold increase in V-4Cr-4Ti yield stress is produced by the formation of dislocation loops (DLs) and fine radiation-induced precipitates (RIPs) with a density of 1.7×1017 cm-3. It is expected that embrittlement of the welds will be worse because density of DLs and RIPs is 1.4-1.6 times higher. Besides, invisible coherent or semi-coherent RIPs are formed in the fusion zone. Elemental maps of the rupture surface of irradiated V-4Cr-4Ti are presented.

  7. On the interdiffusion in multilayered silicide coatings for the vanadium-based alloy V-4Cr-4Ti

    NASA Astrophysics Data System (ADS)

    Chaia, N.; Portebois, L.; Mathieu, S.; David, N.; Vilasi, M.

    2017-02-01

    To provide protection against corrosion at high temperatures, silicide diffusion coatings were developed for the V-4Cr-4Ti alloy, which can be used as the fuel cladding in next-generation sodium-cooled fast breeder reactors. The multilayered coatings were prepared by halide-activated pack cementation using MgF2 as the transport agent and pure silicon (high activity) as the master alloy. Coated pure vanadium and coated V-4Cr-4Ti alloy were studied and compared as substrates. In both cases, the growth of the silicide layers (V3Si, V5Si3, V6Si5 and VSi2) was controlled exclusively by solid-state diffusion, and the growth kinetics followed a parabolic law. Wagner's analysis was adopted to calculate the integrated diffusion coefficients for all silicides. The estimated values of the integrated diffusion coefficients range from approximately 10-9 to 10-13 cm2 s-1. Then, a diffusion-based numerical approach was used to evaluate the growth and consumption of the layers when the coated substrates were exposed at critical temperatures. The estimated lifetimes of the upper VSi2 layer were 400 h and 280 h for pure vanadium and the V-4Cr-4Ti alloy, respectively. The result from the numeric simulation was in good agreement with the layer thicknesses measured after aging the coated samples at 1150 °C under vacuum.

  8. Mineral resource of the month: vanadium

    USGS Publications Warehouse

    Magyar, Michael J.

    2007-01-01

    Vanadium, the name of which comes from Vanadis, a goddess in Scandinavian mythology, is one of the most important ferrous metals. Vanadium has many uses, but the metal’s metallurgical applications, such as an alloying element in iron and steel, account for more than 85 percent of U.S. consumption. The dominant nonmetallurgical use of the metal is as a catalyst for the production of maleic anhydride and sulfuric acid, ceramics, vanadium chemicals and electronics.

  9. The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

    NASA Astrophysics Data System (ADS)

    Madhu, A.; Eraiah, B.

    2018-05-01

    The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

  10. Low activation ferritic alloys

    DOEpatents

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  11. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  12. Self-repairing vanadium-zirconium composite conversion coating for aluminum alloys

    NASA Astrophysics Data System (ADS)

    Zhong, Xin; Wu, Xiaosong; Jia, Yuyu; Liu, Yali

    2013-09-01

    In this paper, new self-repairing vanadium-zirconium composite conversion coating was prepared and investigated by Electrochemical impedance spectra (EIS), Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. EIS results showed that V-Zr conversion coating with hydrogen peroxide modified (VZO) revealed an increasing corrosion resistance in corrosive media which meant a certain self-repairing effect. SEM comparison photos also disclosed that VZO treated with scratches was gradually ameliorated from the initial cracked configuration to fewer cracks and more fillers through an immersion of 3.5% NaCl solution. XPS results demonstrated that the content of vanadium on VZO increased and zirconium declined when immersed in the corrosive solution. This explained further that the self-repairing ability could be related to vanadium. From the above results, we inferred possible structures of VZO and proposed that self-repairing effect was achieved through a hydrolysis condensation polymerization process of vanadate in the localized corrosion area.

  13. Ab initio Investigation of Helium in Vanadium Oxide Nanoclusters

    NASA Astrophysics Data System (ADS)

    Danielson, Thomas; Tea, Eric; Hin, Celine

    Nanostructured ferritic alloys (NFAs) are strong candidate materials for the next generation of fission reactors and future fusion reactors. They are characterized by a large number density of oxide nanoclusters dispersed throughout a BCC iron matrix, where current oxide nanoclusters are primarily comprised of Y-Ti-O compounds. The oxide nanoclusters provide the alloy with high resistance to neutron irradiation, high yield strength and high creep strength at the elevated temperatures of a reactor environment. In addition, the oxide nanoclusters serve as trapping sites for transmutation product helium providing substantially increased resistance to catastrophic cracking and embrittlement. Although the mechanical properties and radiation resistance of the existing NFAs is promising, the problem of forming large scale reactor components continues to present a formidable challenge due to the high hardness and unpredictable fracture behavior of the alloys. An alternative alloy has been previously proposed and fabricated where vanadium is added in order to form vanadium oxide nanoclusters that serve as deflection sites for crack propagation. Although experiments have shown evidence that the fracture behavior of the alloys is improved, it is unknown whether or not the vanadium oxide nanoclusters are effective trapping sites for helium. We present results obtained using density functional theory investigating the thermodynamic stability of helium with the vanadium oxide matrix to make a comparison of trapping effectiveness to traditional Y-Ti-O compounds.

  14. A novel method for vanadium slag comprehensive utilization to synthesize Zn-Mn ferrite and Fe-V-Cr alloy.

    PubMed

    Liu, Shi-Yuan; Li, Shu-Jin; Wu, Shun; Wang, Li-Jun; Chou, Kuo-Chih

    2018-07-15

    Vanadium slag is a by-product from steelmaking process of vanadium-titanium magnetite, which mainly contains FeO, MnO, V 2 O 3 , and Cr 2 O 3 , The elements Fe and Mn are major components of Mn-Zn ferrite. The elements V and Cr are major components of V-Cr alloy. In view of the potential application in these study, a Mn 0.8 Zn 0.2 Fe 2 O 4 of high saturation magnetization (Ms = 68.6 emu/g) and low coercivity (Hc = 3.3 Oe) was successfully synthesized from the leaching solutions of vanadium slag by adding appropriate chemical reagents, ZnCl 2 and MnCl 2 ·4H 2 O, via roasting at 1300 °C for 1 h. The minor components (CaO and SiO 2 ) in the leaching solution of vanadium slag segregated to the grain boundaries resulting in increasing the resistivity of ferrite. The value of DC resistivity of Mn 0.8 Zn 0.2 Fe 2 O 4 at 25 °C reached 1230.7Ω m. The residue containing Fe, V and Cr was chlorinated by AlCl 3 and the Fe 3+ , V 3+ , and Cr 3+ ions were released into the NaCl-KCl eutectic. The current-time curve for the electrolysis of molten salt was investigated. Alloy (Fe, V, and Cr) of granular shape was obtained. The residue can be used to produce the mulite. This process provided a new approach to utilize slag from steelmaking. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Multiplier, moderator, and reflector materials for advanced lithium?vanadium fusion blankets

    NASA Astrophysics Data System (ADS)

    Gohar, Y.; Smith, D. L.

    2000-12-01

    The self-cooled lithium-vanadium fusion blanket concept has several attractive operational and environmental features. In this concept, liquid lithium works as the tritium breeder and coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because of its superior performance relative to other alloys for this application. However, this concept has poor attenuation characteristics and energy multiplication for the DT neutrons. An advanced self-cooled lithium-vanadium fusion blanket concept has been developed to eliminate these drawbacks while maintaining all the attractive features of the conventional concept. An electrical insulator coating for the coolant channels, spectral shifter (multiplier, and moderator) and reflector were utilized in the blanket design to enhance the blanket performance. In addition, the blanket was designed to have the capability to operate at average loading conditions of 2 MW/m 2 surface heat flux and 10 MW/m 2 neutron wall loading. This paper assesses the spectral shifter and the reflector materials and it defines the technological requirements of this advanced blanket concept.

  16. Multiplier, moderator, and reflector materials for lithium-vanadium fusion blankets.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gohar, Y.; Smith, D. L.

    1999-10-07

    The self-cooled lithium-vanadium fusion blanket concept has several attractive operational and environmental features. In this concept, liquid lithium works as the tritium breeder and coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because of its superior performance relative to other alloys for this application. However, this concept has poor attenuation characteristics and energy multiplication for the DT neutrons. An advanced self-cooled lithium-vanadium fusion blanket concept has been developed to eliminate these drawbacks while maintaining all the attractive features of the conventional concept. An electrical insulator coating for the coolantmore » channels, spectral shifter (multiplier, and moderator) and reflector were utilized in the blanket design to enhance the blanket performance. In addition, the blanket was designed to have the capability to operate at high loading conditions of 2 MW/m{sup 2} surface heat flux and 10 MW/m{sup 2} neutron wall loading. This paper assesses the spectral shifter and the reflector materials and it defines the technological requirements of this advanced blanket concept.« less

  17. Vanadium

    USGS Publications Warehouse

    Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Vanadium is used primarily in the production of steel alloys; as a catalyst for the chemical industry; in the making of ceramics, glasses, and pigments; and in vanadium redox-flow batteries (VRBs) for large-scale storage of electricity. World vanadium resources in 2012 were estimated to be 63 million metric tons, which include about 14 million metric tons of reserves. The majority of the vanadium produced in 2012 was from China, Russia, and South Africa.Vanadium is extracted from several different types of mineral deposits and from fossil fuels. These deposits include vanadiferous titanomagnetite (VTM) deposits, sandstone-hosted vanadium (with or without uranium) deposits (SSV deposits), and vanadium-rich black shales. VTM deposits are the principal source of vanadium and consist of magmatic accumulations of ilmenite and magnetite containing 0.2 to 1 weight percent vanadium pentoxide (V2O5). SSV deposits are another important source; these deposits have average ore grades that range from 0.1 to greater than 1 weight percent V2O5. The United States has been and is currently the main producer of vanadium from SSV deposits, particularly those on the Colorado Plateau. Vanadium-rich black shales occur in marine successions that were deposited in epeiric (inland) seas and on continental margins. Concentrations in these shales regularly exceed 0.18 weight percent V2O5 and can be as high as 1.7 weight percent V2O5. Small amounts of vanadium have been produced from the Alum Shale in Sweden and from ferrophosphorus slag generated during the reduction of phosphate to elemental phosphorus in ore from shales of the Phosphoria Formation in Idaho and Wyoming. Because vanadium enrichment occurs in beds that are typically only a few meters thick, most of the vanadiferous black shales are not currently economic, although they may become an important resource in the future. Significant amounts of vanadium are recovered as byproducts of petroleum refining, and processing of coal, tar

  18. Structural and silver/vanadium ratio effects on silver vanadium phosphorous oxide solution formation kinetics: impact on battery electrochemistry.

    PubMed

    Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

    2015-01-21

    The detailed understanding of non-faradaic parasitic reactions which diminish battery calendar life is essential to the development of effective batteries for use in long life applications. The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a battery failure mechanism, yet detailed dissolution studies including kinetic analysis are absent from the literature. The results presented here provide a framework for the quantitative and kinetic analyses of the dissolution of cathode materials which will aid the broader community in more fully understanding this battery failure mechanism. In this study, the dissolution of silver vanadium oxide, representing the primary battery powering implantable cardioverter defibrillators (ICD), is compared with the dissolution of silver vanadium phosphorous oxide (Ag(w)VxPyOz) materials which were targeted as alternatives to minimize solubility. This study contains the first kinetic analyses of silver and vanadium solution formation from Ag0.48VOPO4·1.9H2O and Ag2VP2O8, in a non-aqueous battery electrolyte. The kinetic results are compared with those of Ag2VO2PO4 and Ag2V4O11 to probe the relationships among crystal structure, stoichiometry, and solubility. For vanadium, significant dissolution was observed for Ag2V4O11 as well as for the phosphate oxide Ag0.49VOPO4·1.9H2O, which may involve structural water or the existence of multiple vanadium oxidation states. Notably, the materials from the SVPO family with the lowest vanadium solubility are Ag2VO2PO4 and Ag2VP2O8. The low concentrations and solution rates coupled with their electrochemical performance make these materials interesting alternatives to Ag2V4O11 for the ICD application.

  19. Consolidation and fabrication techniques for vanadium-20 w/o titanium /TV-20/

    NASA Technical Reports Server (NTRS)

    Burt, W. R.; Karasek, F. J.; Kramer, W. C.; Mayfield, R. M.; Mc Gowan, R. D.

    1968-01-01

    Tests of the mechanical properties, fuel compatibility, sodium corrosion and irradiation behavior were made for vanadium and vanadium alloy. Improved methods for consolidation and fabrication of bar, rod, sheet, and high-quality, small diameter, thin-wall tubing of vanadium-20 without titanium are reported.

  20. Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage.

    PubMed

    Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine; Neuefeind, Joerg; Xu, Wenqian; Teng, Xiaowei

    2017-05-23

    Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because the large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate of 5 mV s -1 , corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full cells after 5,000 cycles at 10 C). The promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.

  1. Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage

    DOE PAGES

    Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine; ...

    2017-05-23

    Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate ofmore » 5 mV s -1, corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full-cells after 5,000 cycles at 10 C). Finally, the promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.« less

  2. Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine

    Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate ofmore » 5 mV s -1, corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full-cells after 5,000 cycles at 10 C). Finally, the promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.« less

  3. Growth, Structure, and Photocatalytic Properties of Hierarchical V₂O₅-TiO₂ Nanotube Arrays Obtained from the One-step Anodic Oxidation of Ti-V Alloys.

    PubMed

    Nevárez-Martínez, María C; Mazierski, Paweł; Kobylański, Marek P; Szczepańska, Grażyna; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

    2017-04-05

    V₂O₅-TiO₂ mixed oxide nanotube (NT) layers were successfully prepared via the one-step anodization of Ti-V alloys. The obtained samples were characterized by scanning electron microscopy (SEM), UV-Vis absorption, photoluminescence spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (DRX), and micro-Raman spectroscopy. The effect of the applied voltage (30-50 V), vanadium content (5-15 wt %) in the alloy, and water content (2-10 vol %) in an ethylene glycol-based electrolyte was studied systematically to determine their influence on the morphology, and for the first-time, on the photocatalytic properties of these nanomaterials. The morphology of the samples varied from sponge-like to highly-organized nanotubular structures. The vanadium content in the alloy was found to have the highest influence on the morphology and the sample with the lowest vanadium content (5 wt %) exhibited the best auto-alignment and self-organization (length = 1 μm, diameter = 86 nm and wall thickness = 11 nm). Additionally, a probable growth mechanism of V₂O₅-TiO₂ nanotubes (NTs) over the Ti-V alloys was presented. Toluene, in the gas phase, was effectively removed through photodegradation under visible light (LEDs, λ max = 465 nm) in the presence of the modified TiO₂ nanostructures. The highest degradation value was 35% after 60 min of irradiation. V₂O₅ species were ascribed as the main structures responsible for the generation of photoactive e - and h⁺ under Vis light and a possible excitation mechanism was proposed.

  4. Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

    PubMed

    Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

    2016-02-01

    Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Amorphous Mixed-Valence Vanadium Oxide/Exfoliated Carbon Cloth Structure Shows a Record High Cycling Stability.

    PubMed

    Song, Yu; Liu, Tian-Yu; Yao, Bin; Kou, Tian-Yi; Feng, Dong-Yang; Liu, Xiao-Xia; Li, Yat

    2017-04-01

    Previous studies show that vanadium oxides suffer from severe capacity loss during cycling in the liquid electrolyte, which has hindered their applications in electrochemical energy storage. The electrochemical instability is mainly due to chemical dissolution and structural pulverization of vanadium oxides during charge/discharge cyclings. In this study the authors demonstrate that amorphous mixed-valence vanadium oxide deposited on exfoliated carbon cloth (CC) can address these two limitations simultaneously. The results suggest that tuning the V 4+ /V 5+ ratio of vanadium oxide can efficiently suppress the dissolution of the active materials. The oxygen-functionalized carbon shell on exfoliated CC can bind strongly with VO x via the formation of COV bonding, which retains the electrode integrity and suppresses the structural degradation of the oxide during charging/discharging. The uptake of structural water during charging and discharging processes also plays an important role in activating the electrode material. The amorphous mixed-valence vanadium oxide without any protective coating exhibits record-high cycling stability in the aqueous electrolyte with no capacitive decay in 100 000 cycles. This work provides new insights on stabilizing vanadium oxide, which is critical for the development of vanadium oxide based energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Vanadium-based Ohmic contacts to n-AlGaN in the entire alloy composition

    NASA Astrophysics Data System (ADS)

    France, Ryan; Xu, Tao; Chen, Papo; Chandrasekaran, R.; Moustakas, T. D.

    2007-02-01

    The authors report on the formation and evaluation of V-based Ohmic contacts to n-AlGaN films in the entire alloy composition. The films were produced by plasma assisted molecular beam epitaxy and doped n-type with Si. The conductivity of the films was determined to vary from 103to10-2(Ωcm )-1 as the AlN mole fraction increases from 0% to 100%. Ohmic contacts were formed by e-beam evaporation of V(15nm )/Al(80nm)/V(20nm)/Au(100nm). These contacts were rapid thermal annealed in N2 for 30s at various temperatures. The optimum annealing temperature for this contact scheme to n-GaN is about 650°C and increases monotonically to about 1000°C for 95%-100% AlN mole fraction. The specific contact resistivity was found to be about 10-6Ωcm2 for all films up to 70% AlN mole fraction and then increases to 0.1-1Ωcm2 for films from 95%-100% AlN mole fraction. These results were accounted for by hypothesizing that vanadium, upon annealing, interacts with the nitride film and forms vanadium nitride, which is consistent with reports that it is a metal with low work function.

  7. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

    2015-10-01

    A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  8. Structural and thermal properties of vanadium tellurite glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Rajinder; Kaur, Ramandeep; Khanna, Atul; González, Fernando

    2018-04-01

    V2O5-TeO2 glasses containing 10 to 50 mol% V2O5 were prepared by melt quenching and characterized by X-ray diffraction (XRD), density, Differential Scanning Calorimetry (DSC) and Raman studies.XRD confirmed the amorphous nature of vanadium tellurite samples. The density of the glasses decreases and the molar volume increases on increasing the concentration of V2O5. The thermal properties, such as glass transition temperature Tg, crystallization temperature Tc, and the melting temperature Tm were measured. Tg decreases from a value of 288°C to 232°C. The changes in Tg were correlated with the number of bonds per unit volume, and the average stretching force constant. Raman spectra were used to elucidate the short-range structure of vanadium tellurite glasses.

  9. Vanadium Microalloyed High Strength Martensitic Steel Sheet for Hot-Dip Coating

    NASA Astrophysics Data System (ADS)

    Hutchinson, Bevis; Komenda, Jacek; Martin, David

    Cold rolled steels with various vanadium and nitrogen levels have been treated to simulate the application of galvanizing and galvannealing to hardened martensitic microstructures. Strength levels were raised 100-150MPa by alloying with vanadium, which mitigates the effect of tempering. This opens the way for new ultra-high strength steels with corrosion resistant coatings produced by hot dip galvanising.

  10. Hydrothermal synthesis, crystal structure, and magnetic properties of a new inorganic vanadium(III) phosphate with a chain structure.

    PubMed

    Ferdov, Stanislav; Reis, Mario S; Lin, Zhi; Ferreira, Rute A Sá

    2008-11-03

    A new vanadium(III) phosphate, Na3V(OH)(HPO4)(PO4), has been synthesized by using mild hydrothermal conditions under autogeneous pressure. This material represents a very rare example of sodium vanadium(III) phosphate with a chain structure. The crystal structure has been determined by refinement of powder X-ray diffraction data, starting from the atomic coordinates of an isotypic compound, Na3Al(OH)(HPO4)(PO4), which was obtained under high temperature and high pressure. The phase crystallizes in monoclinic space group C2/m (No. 12) with lattice parameters a = 15.423(9) A, b = 7.280(0) A, c = 7.070(9) A, beta = 96.79(7) degrees, V = 788.3(9) A(3), and Z = 4. The structure consists of one-dimensional chains composed of corner-sharing VO5(OH) octahedra running along the b direction. They are decorated by isolated PO4 and HPO4 tetrahedra sharing two of their corners with the ones of the vanadium octahedra. The interconnection between the chains is assured by three crystallographically distinct Na(+) cations. Magnetic investigation confirms the 3+ oxidation state of the vanadium ions and reveals an antiferromagnetic arrangement between those ions through the chain.

  11. Vanadium—lithium in-pile loop for comprehensive tests of vanadium alloys and multipurpose coatings

    NASA Astrophysics Data System (ADS)

    Lyublinski, I. E.; Evtikhin, V. A.; Ivanov, V. B.; Kazakov, V. A.; Korjavin, V. M.; Markovchev, V. K.; Melder, R. R.; Revyakin, Y. L.; Shpolyanskiy, V. N.

    1996-10-01

    The reliable information on design and material properties of self-cooled Li sbnd Li blanket and liquid metal divertor under neutron radiation conditions can be obtained using the concept of combined technological and material in-pile tests in a vanadium—lithium loop. The method of in-pile loop tests includes studies of vanadium—base alloys resistance, weld resistance under mechanical stress, multipurpose coating formation processes and coatings' resistance under the following conditions: high temperature (600-700°C), lithium velocities up to 10 m/s, lithium with controlled concentration of impurities and technological additions, a neutron load of 0.4-0.5 MW/m 2 and level of irradiation doses up to 5 dpa. The design of such an in-pile loop is considered. The experimental data on corrosion and compatibility with lithium, mechanical properties and welding technology of the vanadium alloys, methods of coatings formation and its radiation tests in lithium environment in the BOR-60 reactor (fast neutron fluence up to 10 26 m -2, irradiation temperature range of 500-523°C) are presented and analyzed as a basis for such loop development.

  12. Controlled coordination in vanadium(V) dimethylhydrazido compounds.

    PubMed

    Sakuramoto, Takashi; Moriuchi, Toshiyuki; Hirao, Toshikazu

    2016-11-01

    The vanadium(V) dimethylhydrazido compounds were structurally characterized to elucidate the effect of the alkoxide ligands in the coordination environment of vanadium(V) hydrazido center. The single-crystal X-ray structure determination of the vanadium(V) dimethylhydrazido compound with isopropoxide ligands revealed a dimeric structure with the V(1)-N(1) distance of 1.680(5)Å, in which each vanadium atom is coordinated in a distorted trigonal-bipyramidal geometry (τ 5 =0.81) with the hydrazido and bridging isopropoxide ligands in the apical positions. On the contrary, nearly tetrahedral arrangement around the vanadium metal center (τ 4 =0.06) with the V(1)-N(1) distance of 1.660(2)Å was observed in the vanadium(V) dimethylhydrazido compound with tert-butoxide ligands. The introduction of the 2,2',2″-nitrilotriethoxide ligand led to a pseudo-trigonal-bipyramidal geometry (τ 5 =0.92) at the vanadium center with the V(1)-N(1) distance of 1.691(5)Å, wherein vanadium atom is pulled out of the plane formed by the nitrilotriethoxide oxygen atoms in the direction of the hydrazido nitrogen. The coordination from the apical ligand in the vanadium(V) dimethylhydrazido compound was found to result in the longer V(1)-N(1) distance. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Structural investigation of phosphate - bismuth glasses with vanadium

    NASA Astrophysics Data System (ADS)

    Stǎnescu, R.; Vedeanu, N.; Cozar, I. B.; Mǎgdaş, A.

    2013-11-01

    The xV2O5(1-dx)[0.5P2O5ṡ0.5Bi2O3] glass system with 0 ≤ x ≤ 50 mol% is investigated by IR and Raman spectroscopy. Both P2O5 and Bi2O3 oxides are known as network formers, but Bi2O3 is an unconventional one. At low content of vanadium oxide (x ≤ 5 mol%), both IR and Raman spectra are dominated by vibration bands characteristics to structural groups of phosphate and bismuthate lattices. Due to the network modifier role, vanadium oxide acts mainly on the Bi2O3 network allowing the phosphate groups to impose their characteristics absorption bands in spectra. These bands are strongly reduced for x ≥ 20 mol% due to the phosphate network depolymerization and the appearance of new vibrations characteristic to P-O-V, Bi-O-V and V-O-V groups showing the network former role of V2O5.

  14. Attachment of Porphyromonas gingivalis to corroded commercially pure titanium and titanium-aluminum-vanadium alloy.

    PubMed

    Barão, Valentim A R; Yoon, Cheon Joo; Mathew, Mathew T; Yuan, Judy Chia-Chun; Wu, Christine D; Sukotjo, Cortino

    2014-09-01

    Titanium dental material can become corroded because of electrochemical interaction in the oral environment. The corrosion process may result in surface modification. It was hypothesized that a titanium surface modified by corrosion may enhance the attachment of periodontal pathogens. This study evaluates the effects of corroded titanium surfaces on the attachment of Porphyromonas gingivalis. Commercially pure titanium (cp-Ti) and titanium-aluminum-vanadium alloy (Ti-6Al-4V) disks were used. Disks were anodically polarized in a standard three-electrode setting in a simulated oral environment with artificial saliva at pH levels of 3.0, 6.5, or 9.0. Non-corroded disks were used as controls. Surface roughness was measured before and after corrosion. Disks were inoculated with P. gingivalis and incubated anaerobically at 37°C. After 6 hours, the disks with attached P. gingivalis were stained with crystal violet, and attachment was expressed based on dye absorption at optical density of 550 nm. All assays were performed independently three times in triplicate. Data were analyzed by two-way analysis of variance, the Tukey honestly significant difference test, t test, and Pearson's correlation test (α = 0.05). Both cp-Ti and Ti-6Al-4V alloy-corroded disks promoted significantly more bacterial attachment (11.02% and 41.78%, respectively; P <0.0001) than did the non-corroded controls. Significantly more (11.8%) P. gingivalis attached to the cp-Ti disks than to the Ti-6Al-4V alloy disks (P <0.05). No significant difference in P. gingivalis attachment was noted among the corroded groups for both cp-Ti and Ti-6Al-4V alloy (P >0.05). There was no significant correlation between surface roughness and P. gingivalis attachment. A higher degree of corrosion on the titanium surface may promote increased bacterial attachment by oral pathogens.

  15. Evaluating transition state structures of vanadium-phosphatase protein complexes using shape analysis.

    PubMed

    Sánchez-Lombardo, Irma; Alvarez, Santiago; McLauchlan, Craig C; Crans, Debbie C

    2015-06-01

    Shape analysis of coordination complexes is well-suited to evaluate the subtle distortions in the trigonal bipyramidal (TBPY-5) geometry of vanadium coordinated in the active site of phosphatases and characterized by X-ray crystallography. Recent studies using the tau (τ) analysis support the assertion that vanadium is best described as a trigonal bipyramid, because this geometry is the ideal transition state geometry of the phosphate ester substrate hydrolysis (C.C. McLauchlan, B.J. Peters, G.R. Willsky, D.C. Crans, Coord. Chem. Rev. http://dx.doi.org/10.1016/j.ccr.2014.12.012 ; D.C. Crans, M.L. Tarlton, C.C. McLauchlan, Eur. J. Inorg. Chem. 2014, 4450-4468). Here we use continuous shape measures (CShM) analysis to investigate the structural space of the five-coordinate vanadium-phosphatase complexes associated with mechanistic transformations between the tetrahedral geometry and the five-coordinate high energy TBPY-5 geometry was discussed focusing on the protein tyrosine phosphatase 1B (PTP1B) enzyme. No evidence for square pyramidal geometries was observed in any vanadium-protein complexes. The shape analysis positioned the metal ion and the ligands in the active site reflecting the mechanism of the cleavage of the organic phosphate in a phosphatase. We identified the umbrella distortions to be directly on the reaction path between tetrahedral phosphate and the TBPY-5-types of high-energy species. The umbrella distortions of the trigonal bipyramid are therefore identified as being the most relevant types of transition state structures for the phosphoryl group transfer reactions for phosphatases and this may be related to the possibility that vanadium is an inhibitor for enzymes that support both exploded and five-coordinate transition states. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Selected fretting-wear-resistant coatings for titanium - 6-percent-aluminum - 4-percent-vanadium alloy

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1976-01-01

    A titanium - 6-percent-aluminum - 4-percent-vanadium alloy (Ti-6Al-4V) was subjected to fretting-wear exposures against uncoated Ti-6Al-4V as a baseline and against various coatings and surface treatments applied to Ti-6Al-4V. The coatings evaluated included plasma-sprayed tungsten carbide with 12 percent cobalt, aluminum oxide with 13 percent titanium oxide, chromium oxide, and aluminum bronze with 10 percent aromatic polyester; polymer-bonded polyimide, polyimide with graphite fluoride, polyimide with molybdenum disulfide (MoS2), and methyl phenyl silicone bonded MoS2, preoxidation surface treatment, a nitride surface treatment, and a sputtered MoS2 coating. Results of wear measurements on both the coated and uncoated surfaces after 300,000 fretting cycles indicated that the polyimide coating was the most wear resistant and caused the least wear to the uncoated mating surface.

  17. Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

    NASA Astrophysics Data System (ADS)

    Mousavi, M.; Khorrami, Gh. H.; Kompany, A.; Yazdi, Sh. Tabatabai

    2017-12-01

    In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V2O5 phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V2O5 phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger.

  18. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  19. Atomic site preferences and structural evolution in vanadium-doped ZrSiO4 from multinuclear solid-state NMR

    NASA Astrophysics Data System (ADS)

    Dajda, N.; Dixon, J. M.; Smith, M. E.; Carthey, N.; Bishop, P. T.

    2003-01-01

    Solid state NMR spectra of 29Si are reported from pure and vanadium-doped zircon (V-ZrSiO4) samples. The vanadium concentration is varied up to ˜1-mol % V4+ by using both conventional-firing and sol-gel routes, and 51V NMR data are also recorded. 17O NMR of 17O isotopically enriched samples shows that the initial gel is completely amorphous with the whole range of possible M-O-M' linkages detected, and that this structure evolves into a fully ordered ZrSiO4 structure with calcination. Static 91Zr NMR data is reported from a pure zircon sample. The NMR data are used to quantify the amount of vanadium entering the zircon structure, and to elucidate its site preference within the lattice. Two contact shifted peaks with very different T1 relaxation from the main zircon peak but attributable to the zircon lattice are observed in the 29Si NMR spectra for all samples. These spectra are consistent with vanadium substitution on both the tetrahedral and dodecahedral sites, with a slight preference for the silicon site. The data show that the relative occupation of these two sites is almost independent of the preparation method and vanadium concentration. At a higher vanadium concentration a third additional peak is observed which may indicate another substitution site. Variable temperature NMR and susceptibility measurements indicate the hyperfine nature of the interactions influencing silicon from V4+ ions in the different sites.

  20. Effect of heat treatment on the structure and hardness of high-entropy alloys CoCrFeNiMnV x ( x = 0.25, 0.5, 0.75, 1)

    NASA Astrophysics Data System (ADS)

    Shaysultanov, D. G.; Stepanov, N. D.; Salishchev, G. A.; Tikhonovsky, M. A.

    2017-06-01

    High-entropy alloys CoCrFeNiMnVKharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 (Kharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 = 0.25, 0.5, 0.75, 1) were prepared by vacuum arc melting. The structure and microhardness of the alloys have been studied in the cast state and after annealing at temperatures of 700-1100°C. It has been found that the alloys consist of the fcc (γ) solid solution and intermetallic sigma (σ) phase. The volume fraction of the σ phase increases with increasing vanadium content. As a result of annealing, phase transformations occur, including the precipitation of σ particles from the γ phase and, vice versa, the precipitation of γ particles from the σ phase. It has been shown that the change in the volume fraction of the σ phase upon annealing occurs due to the changes in the total content of σ-forming elements, chromium and vanadium, in accordance with the lever rule. With increasing temperature, the volume fraction of the σ phase varies nonmonotonically; first, it increases, then it decreases. The microhardness of the alloys correlates well with the change in the volume fraction of the σ phase. The mechanisms of the phase transformations and quantitative relationships between chemical and phase compositions of the alloys and their hardness are discussed.

  1. Homology of vanadium oxide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vasyutinskii, N.A.

    1987-05-01

    The authors examine the homology of vanadium oxide and note that data on the existence of phases and homogeneity limits in the V-O system are very contradictory. A graphical illustration shows the homologous series of vanadium oxides. The predominant part of the discrete formations in the system V-O is characterized by integral stoichiometry and forms six homologous series. It is found that homologous series of vanadium oxides are not only a basis for systematization of such oxides, but also may serve as a means for predicting the composition of new phases, limits of homogeneity, their structure, and properties.

  2. Cellular uptake of titanium and vanadium from addition of salts or fretting corrosion in vitro

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Maurer, A.M.; Merritt, K.; Brown, S.A.

    1994-02-01

    The use of titanium and titanium-6% aluminum-4% vanadium alloy for dental and orthopedic implants has increased in the last decade. The implants are presumed to be compatible because oseointegration, bony apposition, and cell attachment are known. However, the cellular association of titanium and vanadium have remained unknown. This study examined the uptake of salts or fretting corrosion products. Titanium was not observed to be toxic to the cells. Vanadium was toxic at levels greater than 10[mu]g/mL. The percentage of cellular association of titanium was shown to be about 10 times that of vanadium. The percentage of cellular association of eithermore » element was greater from fretting corrosion than from the addition of salts. The presence of vanadium did not affect the cellular uptake of titanium. The presence of titanium decreased the cell association of vanadium.« less

  3. Synthesis of vanadium-doped palladium nanoparticles for hydrogen storage materials

    NASA Astrophysics Data System (ADS)

    Yamamoto, Yuki; Miyachi, Mariko; Yamanoi, Yoshinori; Minoda, Ai; Maekawa, Shunsuke; Oshima, Shinji; Kobori, Yoshihiro; Nishihara, Hiroshi

    2011-12-01

    Palladium-vanadium (Pd/V) alloy nanoparticles stabilized with n-pentyl isocyanide were prepared as new hydrogen storage materials by a facile polyol-based synthetic route with tetraethylene glycol and NaOH at 250 °C. The size distribution of the nanoparticles thus obtained featured two peaks at 4.0 ± 1.1 and 1.4 ± 0.3 nm in diameter, which were the mixture of Pd/V alloy and Pd nanoparticles. The ratio between the number of Pd/V and that of Pd nanoparticles was 51:49, and the Pd:V ratio of the overall product was 9:1 in wt%, indicating that the 4.0 nm Pd/V nanoparticles were composed of 81% Pd and 19% V. The inclusion of vanadium caused the increase in the d-spacing and thus expansion of lattice constant. A rapid increase in hydrogen content at low H2 pressures was observed for the Pd/V nanoparticles, and a 0.47 wt% H2 adsorption capacity was achieved under a H2 pressure of 10 MPa at 303 K. Hydrogen storage performances of Pd/V alloy nanoparticles was superior compared with Pd nanoparticles.

  4. Tensile properties of vanadium-base alloys irradiated in the Fusion-1 low-temperature experiment in the BOR-60 reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tsai, H.; Gazda, J.; Nowicki, L.J.

    The irradiation has been completed and the test specimens have been retrieved from the lithium-bonded capsule at the Research Institute of Atomic Reactors (RIAR) in Russia. During this reporting period, the Argonne National Laboratory (ANL) tensile specimens were received from RIAR and initial testing and examination of these specimens at ANL has been completed. The results, corroborating previous findings showed a significant loss of work hardening capability in the materials. There appears to be no significant difference in behavior among the various heats of vanadium-base alloys in the V-(4-5)Cr-(4-5)Ti composition range. The variations in the preirradiation annealing conditions also producedmore » no notable differences.« less

  5. Nanocrystalline ordered vanadium carbide: Superlattice and nanostructure

    NASA Astrophysics Data System (ADS)

    Kurlov, A. S.; Gusev, A. I.; Gerasimov, E. Yu.; Bobrikov, I. A.; Balagurov, A. M.; Rempel, A. A.

    2016-02-01

    The crystal structure, micro- and nanostructure of coarse- and nanocrystalline powders of ordered vanadium carbide V8C7 have been examined by X-ray and neutron diffraction and electron microscopy methods. The synthesized coarse-crystalline powder of ordered vanadium carbide has flower-like morphology. It was established that the real ordered phase has the composition V8C7-δ (δ ≅ 0.03) deviating from perfect stoichiometric composition V8C7. The vanadium atoms forming the octahedral environment □V6 of vacant sites in V8C7-δ are displaced towards the vacancy □. The presence of carbon onion-like structures was found in the vanadium carbide powders with a small content of free (uncombined) carbon. The nanopowders of V8C7-δ carbide with average particle size of 20-30 nm produced by high-energy milling of coarse-crystalline powder retain the crystal structure of the initial powder, but differ in the lattice deformation distortion anisotropy.

  6. Ordering-separation phase transitions in a Co3V alloy

    NASA Astrophysics Data System (ADS)

    Ustinovshchikov, Yu. I.

    2017-01-01

    The microstructure of the Co3V alloy formed by heat treatment at various temperatures is studied by transmission electron microscopy. Two ordering-separation phase transitions are revealed at temperatures of 400-450 and 800°C. At the high-temperature phase separation, the microstructure consists of bcc vanadium particles and an fcc solid solution; at the low-temperature phase separation, the microstructure is cellular. In the ordering range, the microstructure consists of chemical compound Co3V particles chaotically arranged in the solid solution. The structure of the Co3V alloy is shown not to correspond to the structures indicated in the Co-V phase diagram at any temperatures.

  7. Bioleaching of vanadium from barren stone coal and its effect on the transition of vanadium speciation and mineral phase

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Lin, Hai; Dong, Ying-bo; Li, Gan-yu

    2018-03-01

    This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including the initial pH value, initial Fe2+ concentration, solid load, and inoculum quantity were examined. The results revealed that 48.92wt% of the vanadium was extracted through bioleaching under optimal conditions. Comparatively, the chemical leaching yield (H2SO4, pH 2.0) showed a slower and milder increase in vanadium yield. The vanadium bioleaching yield was 35.11wt% greater than the chemical leaching yield. The Community Bureau of Reference (BCR) sequential extraction results revealed that 88.62wt% of vanadium existed in the residual fraction. The bacteria substantially changed the distribution of the vanadium speciation during the leaching process, and the residual fraction decreased to 48.44wt%. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) results provided evidence that the crystal lattice structure of muscovite was destroyed by the bacteria.

  8. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, Claudette G.; Liu, Chain T.

    1990-01-01

    An improved iron aluminide alloy of the DO.sub.3 type that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy corrosion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26-30 at. % aluminum, 0.5-10 at. % chromium, 0.02-0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron.

  9. Iron aluminide alloys with improved properties for high temperature applications

    DOEpatents

    McKamey, C.G.; Liu, C.T.

    1990-10-09

    An improved iron aluminide alloy of the DO[sub 3] type is described that has increased room temperature ductility and improved high elevated temperature strength. The alloy system further is resistant to corrosive attack in the environments of advanced energy conversion systems such as those using fossil fuels. The resultant alloy is relatively inexpensive as contrasted to nickel based and high nickel steels currently utilized for structural components. The alloy system consists essentially of 26--30 at. % aluminum, 0.5--10 at. % chromium, 0.02--0.3 at. % boron plus carbon, up to 2 at. % molybdenum, up to 1 at. % niobium, up to 0.5 at. % zirconium, up to 0.1 at. % yttrium, up to 0.5 at. % vanadium and the balance iron. 3 figs.

  10. A comparison of implantation-driven permeation characteristics of fusion reactor structural materials

    NASA Astrophysics Data System (ADS)

    Longhurst, G. R.; Anderl, R. A.; Struttmann, D. A.

    1986-11-01

    Implantation-driven permeation experiments have been conducted on samples of the ferritic steel HT-9, the austenitic Primary Candidate Alloy (PCA) and the vanadium alloy V-15Cr-5Ti using D 3+ ions under conditions that simulate charge-exchange neutral loading on a fusion reactor first wall. The steels all exhibited an initially intense permeation "spike" followed by an exponential decrease to low steady-state values. That spike was not evident in the V-15Cr-5Ti experiments. Steady-state permeation was highest in the vanadium alloy and lowest in the austenitic steel. Though permeation rates in the HT-9 were lower than those in V-15Cr-5Ti, permeation transients were much faster in HT-9 than in other materials tested. Sputtering of the steel surface resulted in enhanced reemission, whereas in the vanadium tests, recombination and diffusivity both appeared to diminish as the deuterium concentration rose. We conclude that for conditions comparable to those of these experiments, tritium retention and permeation loss in first wall structures made of steels will be less than in structures made of V-15Cr-5Ti.

  11. Molecular geometry of vanadium dichloride and vanadium trichloride: a gas-phase electron diffraction and computational study.

    PubMed

    Varga, Zoltán; Vest, Brian; Schwerdtfeger, Peter; Hargittai, Magdolna

    2010-03-15

    The molecular geometries of VCl2 and VCl3 have been determined by computations and gas-phase electron diffraction (ED). The ED study is a reinvestigation of the previously published analysis for VCl2. The structure of the vanadium dichloride dimer has also been calculated. According to our joint ED and computational study, the evaporation of a solid sample of VCl2 resulted in about 66% vanadium trichloride and 34% vanadium dichloride in the vapor. Vanadium dichloride is unambiguously linear in its 4Sigma(g)+ ground electronic state. For VCl3, all computations yielded a Jahn-Teller-distorted ground-state structure of C(2v) symmetry. However, it lies merely less than 3 kJ/mol lower than the 3E'' state (D(3h) symmetry). Due to the dynamic nature of the Jahn-Teller effect in this case, rigorous distinction cannot be made between the planar models of either D(3h) symmetry or C(2v) symmetry for the equilibrium structure of VCl3. Furthermore, the presence of several low-lying excited electronic states of VCl3 is expected in the high-temperature vapor. To our knowledge, this is the first experimental and computational study of the VCl3 molecule.

  12. Hyperfine Structure Constants of Energetically High-lying Levels of Odd Parity of Atomic Vanadium

    NASA Astrophysics Data System (ADS)

    Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü.

    2014-09-01

    High-resolution Fourier transform spectra of a vanadium-argon plasma have been recorded in the wavelength range of 365-670 nm (15,000-27,400 cm-1). Optical bandpass filters were used in the experimental setup to enhance the sensitivity of the Fourier transform spectrometer. In total, 138 atomic vanadium spectral lines showing resolved or partially resolved hyperfine structure have been analyzed to determine the magnetic dipole hyperfine structure constants A of the involved energy levels. One of the investigated lines has not been previously classified. As a result, the magnetic dipole hyperfine structure constants A for 90 energy levels are presented: 35 of them belong to the configuration 3d 34s4p and 55 to the configuration 3d 44p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d 34s4p and 44 to 3d 44p.

  13. Formation, structure and bond dissociation thresholds of gas-phase vanadium oxide cluster ions

    NASA Astrophysics Data System (ADS)

    Bell, R. C.; Zemski, K. A.; Justes, D. R.; Castleman, A. W.

    2001-01-01

    The formation and structure of gas-phase vanadium oxide cluster anions are examined using a guided ion beam mass spectrometer coupled with a laser vaporization source. The dominant peaks in the anion total mass distribution correspond to clusters having stoichiometries of the form (VO2)n(VO3)m(O2)q-. Collision-induced dissociation studies of the vanadium oxide species V2O4-6-, V3O6-9-, V4O8-10-, V5O11-13-, V6O13-15-, and V7O16-18- indicate that VO2, VO3, and V2O5 units are the main building blocks of these clusters. There are many similarities between the anion mass distribution and that of the cation distribution studied previously. The principal difference is a shift to higher oxygen content by one additional oxygen atom for the stoichiometric anions (VxOy-) as compared to the cations with the same number of vanadium atoms, which is attributed to the extra pair of electrons of the anionic species. The oxygen-rich clusters, VxOy(O2)-, are shown to more tightly adsorb molecular oxygen than those of the corresponding cationic clusters. In addition, the bond dissociation thresholds for the vanadium oxide clusters ΔE(V+-O)=6.09±0.28 eV, ΔE(OV+-O)=3.51±0.36 eV, and ΔE(O2V--O)=5.43±0.31 eV are determined from the energy-dependent collision-induced dissociation cross sections with Xe as the collision partner. To the best of our knowledge, this is the first bond dissociation energy reported for the breaking of the V-O bond of a vanadium oxide anion.

  14. Laser Weldability of High-Strength Al-Zn Alloys and Its Improvement by the Use of an Appropriate Filler Material

    NASA Astrophysics Data System (ADS)

    Enz, Josephin; Riekehr, Stefan; Ventzke, Volker; Huber, Norbert; Kashaev, Nikolai

    2016-06-01

    Heat-treatable Al-Zn alloys are promising candidates for use as structural lightweight materials in automotive and aircraft applications. This is mainly due to their high strength-to-density ratio in comparison to conventionally employed Al alloys. Laser beam welding is an efficient method for producing joints with high weld quality and has been established in the industry for many years. However, it is well known that aluminum alloys with a high Zn content or, more precisely, with a high (Zn + Mg + Cu) content are difficult to fusion weld due to the formation of porosity and hot cracks. The present study concerns the laser weldability of these hard-to-weld Al-Zn alloys. In order to improve weldability, it was first necessary to understand the reasons for weldability problems and to identify crucial influencing factors. Based on this knowledge, it was finally possible to develop an appropriate approach. For this purpose, vanadium was selected as additional filler material. Vanadium exhibits favorable thermophysical properties and, thereby, can improve the weldability of Al-Zn alloys. The effectiveness of the approach was verified by its application to several Al-Zn alloys with differing amounts of (Zn + Mg + Cu).

  15. Photocatalytic Activity of Vanadium-Substituted ETS-10

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nash,M.; Rykov, S.; Lobo, R.

    2007-01-01

    Various amounts of vanadium have been isomorphously substituted for titanium in ETS-10, creating samples with V/(V+Ti) ratios of 0.13, 0.33, 0.43, and 1.00 and characterized experimentally using Raman, near-edge X-ray absorption fine structure (NEXAFS), X-ray powder diffraction, N{sub 2} adsorption, scanning electron microscopy (SEM), UV/vis spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Raman spectra reveal a disordered chain structure that contains different V-O bonds along with the presence of a V-O-Ti peak. The UV/vis spectra of the vanadium samples have three new absorption features in the visible region at 450, 594, and 850 nm, suggesting both V{sup 4+}more » and V{sup 5+} are present in the samples. NEXAFS results confirm the presence of both V{sup 5+} and V{sup 4+} in the vanadium samples, with a fraction of V{sup 4+} within the range of 0.2-0.4. The addition of vanadium lowers the band gap energy of ETS-10 from 4.32 eV to a minimum of 3.58 eV for the 0.43ETVS-10 sample. Studies of the photocatalytic polymerization of ethylene show that the 594 nm transition has no photocatalytic activity. The visible transition around 450 nm in the vanadium-incorporated samples is photocatalytically active, and the lower-concentration vanadium samples have higher photocatalytic activity than that of ETS-10 and AM-6, the all-vanadium analogue of ETS-10.« less

  16. Reduction and Smelting of Vanadium Titanomagnetite Metallized Pellets

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Chen, Mao; Guo, Yufeng; Jiang, Tao; Zhao, Baojun

    2018-04-01

    Reduction and smelting of the vanadium titanomagnetite metallized pellets have been experimentally investigated in this study. By using the high-temperature smelting, rapid quenching, and electron probe x-ray microanalysis (EPMA) technique, the effects of basicity, reaction time, and graphite reductant amount were investigated. The vanadium contents in iron alloys increase with increasing basicity, reaction time, and graphite amount, whereas the FeO and V2O3 concentrations in the liquid phase decrease with the increase of graphite amount and reaction time. Increasing the reaction time and reductant content promotes the reduction of titanium oxide, whereas the reduction of titanium oxides can be suppressed with increasing the slag basicity. Titanium carbide (TiC) was not observed in all the quenched samples under the present conditions. The experimental results and the FactSage calculations are also compared in the present study.

  17. Vanadium As a Potential Membrane Material for Carbon Capture: Effects of Minor Flue Gas Species.

    PubMed

    Yuan, Mengyao; Liguori, Simona; Lee, Kyoungjin; Van Campen, Douglas G; Toney, Michael F; Wilcox, Jennifer

    2017-10-03

    Vanadium and its surface oxides were studied as a potential nitrogen-selective membrane material for indirect carbon capture from coal or natural gas power plants. The effects of minor flue gas components (SO 2 , NO, NO 2 , H 2 O, and O 2 ) on vanadium at 500-600 °C were investigated by thermochemical exposure in combination with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and in situ X-ray diffraction (XRD). The results showed that SO 2 , NO, and NO 2 are unlikely to have adsorbed on the surface vanadium oxides at 600 °C after exposure for up to 10 h, although NO and NO 2 may have exhibited oxidizing effects (e.g., exposure to 250 ppmv NO/N 2 resulted in an 2.4 times increase in surface V 2 O 5 compared to exposure to just N 2 ). We hypothesize that decomposition of surface vanadium oxides and diffusion of surface oxygen into the metal bulk are both important mechanisms affecting the composition and morphology of the vanadium membrane. The results and hypothesis suggest that the carbon capture performance of the vanadium membrane can potentially be strengthened by material and process improvements such as alloying, operating temperature reduction, and flue gas treatment.

  18. Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

    2017-04-01

    Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

  19. Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review.

    PubMed

    Skyllas-Kazacos, Maria; Cao, Liuyue; Kazacos, Michael; Kausar, Nadeem; Mousa, Asem

    2016-07-07

    The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Optical modulation in silicon-vanadium dioxide photonic structures

    NASA Astrophysics Data System (ADS)

    Miller, Kevin J.; Hallman, Kent A.; Haglund, Richard F.; Weiss, Sharon M.

    2017-08-01

    All-optical modulators are likely to play an important role in future chip-scale information processing systems. In this work, through simulations, we investigate the potential of a recently reported vanadium dioxide (VO2) embedded silicon waveguide structure for ultrafast all-optical signal modulation. With a VO2 length of only 200 nm, finite-differencetime- domain simulations suggest broadband (200 nm) operation with a modulation greater than 12 dB and an insertion loss of less than 3 dB. Predicted performance metrics, including modulation speed, modulation depth, optical bandwidth, insertion loss, device footprint, and energy consumption of the proposed Si-VO2 all-optical modulator are benchmarked against those of current state-of-the-art all-optical modulators with in-plane optical excitation.

  1. Structure-property relationships in NOx sensor materials composed of arrays of vanadium oxide nanoclusters

    NASA Astrophysics Data System (ADS)

    Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.; Ganegoda, Hasitha; Khan, M. Ishaque

    2017-12-01

    The mixed-valent vanadium oxide based three-dimensional framework structure species [Cd3(H2O)12V16IVV2VO36(OH)6 (AO4)]·24H2O, (A = V,S) (Cd3(VO)o) represents a rare example of an interesting sensor material which exhibits NOx {NO + NO2} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd3(VO)o decreases in air. Combined characterization studies revealed that the building block, {V18O42(AO4)} cluster, of 3-D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadium which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd3(VO)o. Based on these results we propose that the changes in semiconducting properties of Cd3(VO)o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.

  2. Imaging of Vanadium in Microfossils: A New Potential Biosignature

    NASA Astrophysics Data System (ADS)

    Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.; Lai, Barry; Vogt, Stefan; Breuer, Pierre; Steemans, Philippe; Lay, Peter A.

    2017-11-01

    The inability to unambiguously distinguish the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from nonbiological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This, too, is important for the search for life on Mars by in situ analyses via rovers or sample return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biological origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagenesis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. We propose that, taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenicity of putative microfossil-like structures.

  3. Design of new face-centered cubic high entropy alloys by thermodynamic calculation

    NASA Astrophysics Data System (ADS)

    Choi, Won-Mi; Jung, Seungmun; Jo, Yong Hee; Lee, Sunghak; Lee, Byeong-Joo

    2017-09-01

    A new face-centered cubic (fcc) high entropy alloy system with non-equiatomic compositions has been designed by utilizing a CALculation of PHAse Diagram (CALPHAD) - type thermodynamic calculation technique. The new alloy system is based on the representative fcc high entropy alloy, the Cantor alloy which is an equiatomic Co- Cr-Fe-Mn-Ni five-component alloy, but fully or partly replace the cobalt by vanadium and is of non-equiatomic compositions. Alloy compositions expected to have an fcc single-phase structure between 700 °C and melting temperatures are proposed. All the proposed alloys are experimentally confirmed to have the fcc single-phase during materials processes (> 800 °C), through an X-ray diffraction analysis. It is shown that there are more chances to find fcc single-phase high entropy alloys if paying attention to non-equiatomic composition regions and that the CALPHAD thermodynamic calculation can be an efficient tool for it. An alloy design technique based on thermodynamic calculation is demonstrated and the applicability and limitation of the approach as a design tool for high entropy alloys is discussed.

  4. Vanadium K-edge XAS studies on the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis.

    PubMed

    Renirie, Rokus; Charnock, John M; Garner, C David; Wever, Ron

    2010-06-01

    Vanadium K-edge X-ray Absorption Spectra have been recorded for the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis at pH 6.0. The Extended X-ray Absorption Fine Structure (EXAFS) regions provide a refinement of previously reported crystallographic data; one short V=O bond (1.54A) is present in both forms. For the native enzyme, the vanadium is coordinated to two other oxygen atoms at 1.69A, another oxygen atom at 1.93A and the nitrogen of an imidazole group at 2.02A. In the peroxo-form, the vanadium is coordinated to two other oxygen atoms at 1.67A, another oxygen atom at 1.88A and the nitrogen of an imidazole group at 1.93A. When combined with the available crystallographic and kinetic data, a likely interpretation of the EXAFS distances is a side-on bound peroxide involving V-O bonds of 1.67 and 1.88A; thus, the latter oxygen would be 'activated' for transfer. The shorter V-N bond observed in the peroxo-form is in line with the previously reported stronger binding of the cofactor in this form of the enzyme. Reduction of the enzyme with dithionite has a clear influence on the spectrum, showing a change from vanadium(V) to vanadium(IV).

  5. Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures

    NASA Astrophysics Data System (ADS)

    Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G.; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-Ju; Jang, Won Ick; Yu, Han Young

    2012-02-01

    Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm-3 and 40-80 m2 g-1, respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

  6. Production of large-scale, freestanding vanadium pentoxide nanobelt porous structures.

    PubMed

    Yun, Yong Ju; Kim, Byung Hoon; Hong, Won G; Kim, Chang Hee; Kim, Yark Yeon; Jeong, Eun-ju; Jang, Won Ick; Yu, Han Young

    2012-03-07

    Large-scale, freestanding, porous structures of vanadium pentoxide nanobelts (VPNs) were successfully prepared using the template-free freeze-drying method. The porous and multi-layered VPN macrostructures are composed of randomly oriented long nanobelts (over 100 μm) and their side length can be controlled up to a few tens of centimetres. Also, the bulk density and surface area of these macrostructures are 3-5 mg cm(-3) and 40-80 m(2) g(-1), respectively, which are similar to those of the excellent adsorbents. In addition, the removal efficiency measurements of ammonia molecules revealed that the VPN porous structures can adsorb the ammonia molecules with the combinations of van der Waals forces and strong chemical bonding by functional groups on the VPN surface.

  7. A well-defined terminal vanadium(III) oxo complex.

    PubMed

    King, Amanda E; Nippe, Michael; Atanasov, Mihail; Chantarojsiri, Teera; Wray, Curtis A; Bill, Eckhard; Neese, Frank; Long, Jeffrey R; Chang, Christopher J

    2014-11-03

    The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.

  8. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    DOEpatents

    Brady, Michael P [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  9. Positron lifetime in vanadium oxide bronzes

    NASA Astrophysics Data System (ADS)

    Dryzek, J.; Dryzek, E.

    2003-09-01

    The positron lifetime (PL) and Doppler broadening (DB) of annihilation line measurements have been performed in vanadium oxide bronzes MxV2O5. The dependence of these annihilation characteristics on the kind and concentration of the metal M donor has been observed. In the PL spectrum only one lifetime component has been detected in all studied bronzes. The results indicate the positron localization in the structural tunnels present in the crystalline lattice of the vanadium oxide bronzes. (

  10. Insulating phases of vanadium dioxide are Mott-Hubbard insulators

    DOE PAGES

    Huffman, T. J.; Hendriks, C.; Walter, E. J.; ...

    2017-02-15

    Here, we present comprehensive broadband optical spectroscopy data on two insulating phases of vanadium dioxide (VO 2): monoclinic M 2 and triclinic. The main result of our work is that the energy gap and the electronic structure are essentially unaltered by the first-order structural phase transition between the M 2 and triclinic phases. Moreover, the optical interband features in the M 2 and triclinic phases are remarkably similar to those observed in the well-studied monoclinic M 1 insulating phase of VO 2. As the energy gap is insensitive to the different lattice structures of the three insulating phases, we rulemore » out vanadium-vanadium pairing (the Peierls component) as the dominant contributor to the opening of the gap. Rather, the energy gap arises primarily from intra-atomic Coulomb correlations.« less

  11. Vanadium Respiration by Geobacter metallireducens: Novel Strategy for In Situ Removal of Vanadium from Groundwater

    PubMed Central

    Ortiz-Bernad, Irene; Anderson, Robert T.; Vrionis, Helen A.; Lovley, Derek R.

    2004-01-01

    Vanadium can be an important contaminant in groundwaters impacted by mining activities. In order to determine if microorganisms of the Geobacteraceae, the predominant dissimilatory metal reducers in many subsurface environments, were capable of reducing vanadium(V), Geobacter metallireducens was inoculated into a medium in which acetate was the electron donor and vanadium(V) was the sole electron acceptor. Reduction of vanadium(V) resulted in the production of vanadium(IV), which subsequently precipitated. Reduction of vanadium(V) was associated with cell growth with a generation time of 15 h. No vanadium(V) was reduced and no precipitate was formed in heat-killed or abiotic controls. Acetate was the most effective of all the electron donors evaluated. When acetate was injected into the subsurface to enhance the growth and activity of Geobacteraceae in an aquifer contaminated with uranium and vanadium, vanadium was removed from the groundwater even more effectively than uranium. These studies demonstrate that G. metallireducens can grow via vanadium(V) respiration and that stimulating the activity of Geobacteraceae, and hence vanadium(V) reduction, can be an effective strategy for in situ immobilization of vanadium in contaminated subsurface environments. PMID:15128571

  12. Imaging of Vanadium in Microfossils: A New Potential Biosignature

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.

    Being able to distinguish unambiguously the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from non-biological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This too, is important for the search for life on Mars; either by in situ analyses via rovers, or sample return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biologicalmore » origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature, that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagensis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. Here, we propose that taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenecity of putative microfossil-like structures.« less

  13. Imaging of Vanadium in Microfossils: A New Potential Biosignature

    DOE PAGES

    Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.; ...

    2017-11-01

    Being able to distinguish unambiguously the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from non-biological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This too, is important for the search for life on Mars; either by in situ analyses via rovers, or sample return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biologicalmore » origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature, that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagensis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. Here, we propose that taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenecity of putative microfossil-like structures.« less

  14. Structure and stability of hexa-aqua V(III) cations in vanadium redox flow battery electrolytes.

    PubMed

    Vijayakumar, M; Li, Liyu; Nie, Zimin; Yang, Zhenguo; Hu, JianZhi

    2012-08-07

    The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by (17)O and (35/37)Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction.

  15. Syntheses, structures and characterizations of three novel vanadium selenites with organically bonded copper/nickel complex

    NASA Astrophysics Data System (ADS)

    Qian, Cheng; Kong, Fang; Mao, Jiang-Gao

    2016-06-01

    A series of vanadium selenites covalently bonded with metal-organic complex, namely, Ni(2,2-bipy)2V2O4(SeO3)2 (1), Cu(2,2-bipy)V2O4(SeO3)2·0.5H2O (2) and Cu2(2,2-bipy)2V5O12(SeO3)2 (3) (2,2-bipy=2,2-bipyridine) have been hydrothermally synthesized and structurally characterized. They exhibit three different structural dimensions, from 0D cluster, 1D chain to 2D layer. Compound 1 features a 0D {Ni(2,2-bipy)2V2O4(SeO3)2}2 dimeric cluster composed of two {Ni(2,2-bipy)2}2+ moieties connected by the {V4O8(SeO3)4}4- cluster. Compound 2 shows a 1D {Cu(2,2-bipy)V2O4(SeO3)2}n chain in which the {Cu2(2,2-bipy)2}4+ moieties are bridged by the {V4O8(SeO3)4}4- clusters. Compound 3 displays a 2D structure consisted of mixed valence vanadium selenites layers {VIVVV4SeIV2O18}n4- and {Cu(2,2-bipy)}2+ complex moieties. The adjacent layers are further interconnected via π-π interactions between the 2,2-bipy ligands exhibiting an interesting 3D supramolecular architecture. Both compound 1 and 2 contain a new {V4O8(SeO3)4}4- cluster and compound 3 exhibits the first 2D vanadate polyhedral layer in vanadium selenites/tellurites with organic moieties.

  16. Electrical resistivity of V-Cr-Ti alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

    1997-04-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

  17. Microstructure and mechanical properties of diamond films on titanium-aluminum-vanadium alloy

    NASA Astrophysics Data System (ADS)

    Catledge, Shane Aaron

    The primary focus of this dissertation is the investigation of the processing-structure-property relationships of diamond films deposited on Ti-6Al-4V alloy by microwave plasma chemical vapor deposition (MPCVD). By depositing a well-adhered protective layer of diamond on an alloy component, its hardness, wear-resistance, performance, and overall lifetime could be significantly increased. However, due to the large thermal expansion mismatch between the diamond film and metal (and the corresponding residual stress induced in the film), film adhesion is typically unsatisfactory and often results in immediate delamination after processing. Therefore, it is a major goal of this research to improve adhesion of the diamond film to the alloy substrate. Through the use of innovative processing techniques involving MPCVD deposition conditions and methane (CH4), nitrogen (N2), and hydrogen (H2) chemistry, we have achieved diamond films which consistently adhere to the alloy substrate. In addition, we have discovered that, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well-faceted diamond to nanocrystalline diamond with extremely low surface roughness (as low as 27 nm). The relationship between processing and structure was studied using in-situ optical emission spectroscopy, micro-Raman spectroscopy, surface profilometry, glancing-angle x-ray diffraction, and scanning electron microscopy. We observe that when nitrogen is added to the H2/CH4 feedgas mixture, a carbon-nitrogen (CN) emission band arises and its relative abundance to the carbon dimer (C2) gas species is shown to have a pronounced influence on the diamond film structure. By appropriate choice of deposition chemistry and conditions, we can tailor the diamond film structure and its corresponding properties. The mechanical properties of interest in this thesis are those relating to the integrity of the film/substrate interface, as well as the

  18. Additive Manufacturing of Metastable Beta Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Yannetta, Christopher J.

    Additive manufacturing processes of many alloys are known to develop texture during the deposition process due to the rapid reheating and the directionality of the dissipation of heat. Titanium alloys and with respect to this study beta titanium alloys are especially susceptible to these effects. This work examines Ti-20wt%V and Ti-12wt%Mo deposited under normal additive manufacturing process parameters to examine the texture of these beta-stabilized alloys. Both microstructures contained columnar prior beta grains 1-2 mm in length beginning at the substrate with no visible equiaxed grains. This microstructure remained constant in the vanadium system throughout the build. The microstructure of the alloy containing molybdenum changed from a columnar to an equiaxed structure as the build height increased. Eighteen additional samples of the Ti-Mo system were created under different processing parameters to identify what role laser power and travel speed have on the microstructure. There appears to be a correlation in alpha lath size and power density. The two binary alloys were again deposited under the same conditions with the addition of 0.5wt% boron to investigate the effects an insoluble interstitial alloying element would have on the microstructure. The size of the prior beta grains in these two alloys were reduced with the addition of boron by approximately 50 (V) and 100 (Mo) times.

  19. Leaching characteristics of vanadium in mine tailings and soils near a vanadium titanomagnetite mining site.

    PubMed

    Yang, Jinyan; Tang, Ya; Yang, Kai; Rouff, Ashaki A; Elzinga, Evert J; Huang, Jen-How

    2014-01-15

    A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with <1% of the total vanadium readily mobilised. Column experiments revealed that only <0.1% of vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20μgL(-1) to 50-90μgL(-1), indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johnson, W.R.; Smith, J.P.; Trester, P.W.

    1997-04-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy, and processing into final sheet and rod product forms suitable for components of the DIII-D Radiative Divertor structure, has been completed at Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RD Program, and research into several joining methods for fabrication of the RD components, including resistance seam, friction, and electron beam welding,more » is continuing. Preliminary trials have been successful in the joining of V-alloy to itself by electron beam, resistance, and friction welding processes, and to Inconel 625 by friction welding. An effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625 has also been initiated, and results have been encouraging. In addition, preliminary tests have been completed to evaluate the susceptibility of V-4Cr-4Ti alloy to stress corrosion cracking in DIII-D cooling water, and the effects of exposure to DIII-D bakeout conditions on the tensile and fracture behavior of V-4Cr-4Ti alloy.« less

  1. Structural investigation of new vanadium-bismuth-phosphate glasses by IR and ESR spectroscopy

    NASA Astrophysics Data System (ADS)

    Vedeanu, N.; Cozar, O.; Stanescu, R.; Cozar, I. B.; Ardelean, I.

    2013-07-01

    IR spectra changes of the xV2O5(1 - x)[0.8P2O5ṡ0.2Bi2O3] glass system with 0 ⩽ x ⩽ 50 mol% show that vanadium oxide acts as a network modifier at low concentration (x ⩽ 5 mol%), affecting especially the Bi2O3 network. In the same time the phosphate groups (structures) impose their presence by themselves, fact which is illustrated by the increasing of the intensity of characteristic 910, 1040, 1230 cm-1 bands. The IR bands belonging to the phosphate groups are strongly reduced for x ⩾ 10 mol% due to the phosphate network depolymerization and to the appearance of new vibrations characteristic for POV and VOV linkages, showing the network former role of V2O5. In the same time the changes observed in the ESR spectra of these glasses are explained supposing the superposition of two signals, one with a well-resolved hyperfine structure typical for isolated V4+ ions and a broad line characteristic for clustered ions. The line width dependence versus V2O5 content shows that dipole-dipole interactions exist between vanadium ions until x = 5 mol% and the superexchange interactions prevail at high content (x ⩾ 10 mol%).

  2. Alloy and structural optimization of a directionally solidified lamellar eutectic alloy

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.

    1976-01-01

    Mechanical property characterization tests of a directionally solidified Ni-20 percent Cb-2.5 percent Al-6 percent Cr cellular eutectic turbine blade alloy demonstrated excellent long time creep stability and indicated intermediate temperature transverse tensile ductility and shear strength to be somewhat low for turbine blade applications. Alloy and structural optimization significantly improves these off-axis properties with no loss of longitudinal creep strength or stability. The optimized alloy-structure combination is a carbon modified Ni-20.1 percent Cb-2.5 percent Al-6.0 percent Cr-0.06 percent C composition processed under conditions producing plane front solidification and a fully-lamellar microstructure. With current processing technology, this alloy exhibits a creep-rupture advantage of 39 C over the best available nickel base superalloy, directionally solidified MAR M200+ Hf. While improved by about 20 percent, shear strength of the optimized alloy remains well below typical superalloy values.

  3. Aluminum Alloy and Article Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2003-01-01

    A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

  4. Mechanical property changes induced in structural alloys by neutron irradiations with different helium to displacement ratios*1

    NASA Astrophysics Data System (ADS)

    Mansur, L. K.; Grossbeck, M. L.

    1988-07-01

    Effects of helium on mechanical properties of irradiated structural materials are reviewed. In particular, variations in response to the ratio of helium to displacement damage serve as the focus. Ductility in creep and tensile tests is emphasized. A variety of early work has led to the current concentration on helium effects for fusion reactor materials applications. A battery of techniques has been developed by which the helium to displacement ratio can be varied. Our main discussion is devoted to the techniques of spectral tailoring and isotopic alloying currently of interest for mixed-spectrum reactors. Theoretical models of physical mechanisms by which helium interacts with displacement damage have been developed in terms of hardening to dislocation motion and grain boundary cavitation. Austenitic stainless steels, ferritic/martensitic steels and vanadium alloys are considered. In each case, work at low strain rates, where the main problems may lie, at the helium to displacement ratios appropriate to fusion reactor materials is lacking. Recent experimental evidence suggests that both in-reactor and high helium results may differ substantially from post-irradiation or low helium results. It is suggested that work in these areas is especially needed.

  5. Irradiation effects on 17-7 PH stainless steel, A-201 carbon steel, and titanium-6-percent-aluminum-4-percent-vanadium alloy

    NASA Technical Reports Server (NTRS)

    Hasse, R. A.; Hartley, C. B.

    1972-01-01

    Irradiation effects on three materials from the NASA Plum Brook Reactor Surveillance Program were determined. An increase of 105 K in the nil-ductility temperature for A-201 steel was observed at a fluence of approximately 3.1 x 10 to the 18th power neutrons/sq cm (neutron energy E sub n greater than 1.0 MeV). Only minor changes in the mechanical properties of 17-7 PH stainless steel were observed up to a fluence of 2 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV). The titanium-6-percent-aluminum-4-percent-vanadium alloy maintained its notch toughness up to a fluence of 1 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV).

  6. Modification of surface properties of copper-refractory metal alloys

    DOEpatents

    Verhoeven, John D.; Gibson, Edwin D.

    1993-10-12

    The surface properties of copper-refractory metal (CU-RF) alloy bodies are modified by heat treatments which cause the refractory metal to form a coating on the exterior surfaces of the alloy body. The alloys have a copper matrix with particles or dendrites of the refractory metal dispersed therein, which may be niobium, vanadium, tantalum, chromium, molybdenum, or tungsten. The surface properties of the bodies are changed from those of copper to that of the refractory metal.

  7. Vanadium K-edge X-ray absorption spectroscopy of bromoperoxidase from Ascophyllum nodosum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Arber, J.M.; de Boer, E.; Garner, C.D.

    Bromoperoxidase from Ascophyllum nodusum was the first vanadium-containing enzyme to be isolated. X-ray absorption spectra have now been collected in order to investigate the coordination of vanadium in the native, native plus bromide, native plus hydrogen peroxide, and dithionite-reduced forms of the enzyme. The edge and X-ray absorption near-edge structures show that, in the four samples studied, it is only on reduction of the native enzyme that the metal site is substantially altered. In addition, these data are consistent with the presence of vanadium(IV) in the reduced enzyme and vanadium(V) in the other samples. Extended X-ray absorption fine structure datamore » confirm that there are structural changes at the metal site on reduction of the native enzyme, notably a lengthening of the average inner-shell distance, and the presence of terminal oxygen together with histidine and oxygen-donating residues.« less

  8. Bioaccumulation of Vanadium by Vanadium-Resistant Bacteria Isolated from the Intestine of Ascidia sydneiensis samea.

    PubMed

    Romaidi; Ueki, Tatsuya

    2016-06-01

    Isolation of naturally occurring bacterial strains from metal-rich environments has gained popularity due to the growing need for bioremediation technologies. In this study, we found that the vanadium concentration in the intestine of the vanadium-rich ascidian Ascidia sydneiensis samea could reach 0.67 mM, and thus, we isolated vanadium-resistant bacteria from the intestinal contents and determined the ability of each bacterial strain to accumulate vanadium and other heavy metals. Nine strains of vanadium-resistant bacteria were successfully isolated, of which two strains, V-RA-4 and S-RA-6, accumulated vanadium at a higher rate than did the other strains. The maximum vanadium absorption by these bacteria was achieved at pH 3, and intracellular accumulation was the predominant mechanism. Each strain strongly accumulated copper and cobalt ions, but accumulation of nickel and molybdate ions was relatively low. These bacterial strains can be applied to protocols for bioremediation of vanadium and heavy metal toxicity.

  9. Simultaneous increase in the strength, plasticity, and corrosion resistance of an ultrafine-grained Ti-4Al-2V pseudo-alpha-titanium alloy

    NASA Astrophysics Data System (ADS)

    Chuvil'deev, V. N.; Kopylov, V. I.; Nokhrin, A. V.; Bakhmet'ev, A. M.; Sandler, N. G.; Kozlova, N. A.; Tryaev, P. V.; Tabachkova, N. Yu.; Mikhailov, A. S.; Ershova, A. V.; Gryaznov, M. Yu.; Chegurov, M. K.; Sysoev, A. N.; Smirnova, E. S.

    2017-05-01

    The influence of severe plastic deformation on the structural-phase state of grain boundaries in a Ti-4Al-2V (commercial PT3V grade) pseudo-alpha-titanium alloy has been studied. It is established that increase in the strength, plasticity, and corrosion resistance of this alloy is related to the formation of an ultrafine- grained structure. In particular, it is shown that an increase in the resistance to hot-salt intergranular corrosion is due to diffusion-controlled redistribution of aluminum and vanadium atoms at the grain boundaries of titanium formed during thermal severe plastic deformation.

  10. X-ray absorption near-edge structure micro-spectroscopy study of vanadium speciation in Phycomyces blakesleeanus mycelium.

    PubMed

    Žižić, Milan; Dučić, Tanja; Grolimund, Daniel; Bajuk-Bogdanović, Danica; Nikolic, Miroslav; Stanić, Marina; Križak, Strahinja; Zakrzewska, Joanna

    2015-09-01

    Vanadium speciation in the fungus Phycomyces blakesleeanus was examined by X-ray absorption near-edge structure (XANES) spectroscopy, enabling assessment of oxidation states and related molecular symmetries of this transition element in the fungus. The exposure of P. blakesleeanus to two physiologically important vanadium species (V(5+) and V(4+)) resulted in the accumulation of this metal in central compartments of 24 h old mycelia, most probably in vacuoles. Tetrahedral V(5+), octahedral V(4+), and proposed intracellular complexes of V(5+) were detected simultaneously after addition of a physiologically relevant concentration of V(5+) to the mycelium. A substantial fraction of the externally added V(4+) remained mostly in its original form. However, observable variations in the pre-edge-peak intensities in the XANES spectra indicated intracellular complexation and corresponding changes in the molecular coordination symmetry. Vanadate complexation was confirmed by (51)V NMR and Raman spectroscopy, and potential binding compounds including cell-wall constituents (chitosan and/or chitin), (poly)phosphates, DNA, and proteins are proposed. The evidenced vanadate complexation and reduction could also explain the resistance of P. blakesleeanus to high extracellular concentrations of vanadium.

  11. Thirty years through vanadium chemistry.

    PubMed

    Costa Pessoa, J

    2015-06-01

    The relevance of vanadium in biological systems is known for many years and vanadium-based catalysts have important industrial applications, however, till the beginning of the 80s research on vanadium chemistry and biochemistry did not receive much attention from the scientific community. The understanding of the broad bioinorganic implications resulting from the similarities between phosphate and vanadate(V) and the discovery of vanadium dependent enzymes gave rise to an enormous increase in interest in the chemistry and biological relevance of vanadium. Thereupon the last 30years corresponded to a period of enormous research effort in these fields, as well as in medicinal applications of vanadium and in the development of catalysts for use in fine-chemical synthesis, some of these inspired by enzymatic active sites. Since the 80s my group in collaboration with others made contributions, described throughout this text, namely in the understanding of the speciation of vanadium compounds in aqueous solution and in biological fluids, and to the transport of vanadium compounds in blood plasma and their uptake by cells. Several new types of vanadium compounds were also synthesized and characterized, with applications either as prospective therapeutic drugs or as homogeneous or heterogenized catalysts for the production of fine chemicals. The developments made are described also considering the international context of the evolution of the knowledge in the chemistry and bioinorganic chemistry of vanadium compounds during the last 30years. This article was compiled based on the Vanadis Award presentation at the 9th International Vanadium Symposium. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Structure, hydrolysis, and diffusion of aqueous vanadium ions from Car-Parrinello molecular dynamics

    NASA Astrophysics Data System (ADS)

    Jiang, Zhen; Klyukin, Konstantin; Alexandrov, Vitaly

    2016-09-01

    A molecular level understanding of the properties of electroactive vanadium species in aqueous solution is crucial for enhancing the performance of vanadium redox flow batteries. Here, we employ Car-Parrinello molecular dynamics simulations based on density functional theory to investigate the hydration structures, first hydrolysis reaction, and diffusion of aqueous V2+, V3+, VO2+, and VO 2+ ions at 300 K. The results indicate that the first hydration shell of both V2+ and V3+ contains six water molecules, while VO2+ is coordinated to five and VO 2+ to three water ligands. The first acidity constants (pKa) estimated using metadynamics simulations are 2.47, 3.06, and 5.38 for aqueous V3+, VO 2+ , and VO2+, respectively, while V2+ is predicted to be a fairly weak acid in aqueous solution with a pKa value of 6.22. We also show that the presence of chloride ions in the first coordination sphere of the aqueous VO 2+ ion has a significant impact on water hydrolysis leading to a much higher pKa value of 4.8. This should result in a lower propensity of aqueous VO 2+ for oxide precipitation reaction in agreement with experimental observations for chloride-based electrolyte solutions. The computed diffusion coefficients of vanadium species in water at room temperature are found to increase as V 3 + < VO 2 + < V O 2 + < V 2 + and thus correlate with the simulated hydrolysis constants, namely, the higher the pKa value, the greater the diffusion coefficient.

  13. Reactive Spark Plasma Sintering (SPS) of Nitride Reinforced Titanium Alloy Composites (Postprint)

    DTIC Science & Technology

    2014-08-15

    AFRL-RX-WP-JA-2014-0177 REACTIVE SPARK PLASMA SINTERING (SPS) OF NITRIDE REINFORCED TITANIUM ALLOY COMPOSITES (POSTPRINT) Jaimie S...titanium–vanadium alloys, has been achieved by introducing reactive nitrogen gas during the spark plasma sintering (SPS) of blended titanium and...lcomReactive spark plasma sintering (SPS) of nitride reinforced titanium alloy compositeshttp://dx.doi.org/10.1016/j.jallcom.2014.08.049 0925-8388

  14. Dynamic structural colour using vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Wilson, K.; Marocico, C. A.; Bradley, A. L.

    2018-06-01

    A thin film stack consisting of layers of indium tin oxide (ITO) with an intermediate vanadium oxide (VO2) layer on an optically thick silver film has been investigated for dynamic structural colour. The structure benefits from the phase change properties of VO2. Compared with other phase change materials, such as germanium antimony telluride (GST), VO2 can be offered as a lower power consumption alternative. It has been overlooked in the visible spectral range due to its smaller refractive index change below 700 nm. We demonstrate that the sensitivity of the visible reflectance spectrum to the change in phase of a 30 nm VO2 layer is increased after it is incorporated in a thin film stack, with performance comparable to other phase change materials. The extent to which dynamic tuning of the reflectance spectra of ITO–VO2–ITO–Ag thin film stacks can be exploited for colour switching is reported, with approximately 25% change in reflectance demonstrated at 550 nm. Inclusion of a top ITO layer is also shown to improve the chromaticity change on phase transition.

  15. Effect of vanadium doping on structural and magnetic properties of defective nano-nickel ferrite

    NASA Astrophysics Data System (ADS)

    Heiba, Zein K.; Mohamed, Mohamed Bakr; Wahba, Adel Maher; Almalowi, M. I.

    2018-04-01

    Nano-nickel ferrites defected by vanadium doping (NiV x Fe2-1.67 x O4, 0 ≤ x ≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values ( x = 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content ( x ≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ˜ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization ( M S) or coercivity (H C) with the content of nonmagnetic V5+. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V5+, making present samples potential electrodes for Li- or Na-ion batteries.

  16. DNA damage induction in human cells exposed to vanadium oxides in vitro.

    PubMed

    Rodríguez-Mercado, Juan J; Mateos-Nava, Rodrigo A; Altamirano-Lozano, Mario A

    2011-12-01

    Vanadium and vanadium salts cause genotoxicity and elicit variable biological effects depending on several factors. In the present study, we analyzed and compared the DNA damage and repair processes induced by vanadium in three oxidation states. We used human blood leukocytes in vitro and in a single cell gel electrophoresis assay at two pH values. We observed that vanadium(III) trioxide and vanadium(V) pentoxide produced DNA single-strand breaks at all of the concentrations (1, 2, 4, or 8 μg/ml) and treatment times (2, 4, or 6 h) tested. Vanadium(IV) tetraoxide treatment significantly increased DNA damage at all concentrations for 4 or 6 h of treatment but not for 2 h of treatment. The DNA repair kinetics indicated that most of the cells exposed to vanadium III and V for 4 h recovered within the repair incubation time of 90 min; however, those exposed to vanadium(IV) repaired their DNA within 120 min. The data at pH 9 indicated that vanadium(IV) tetraoxide induced DNA double-strand breaks. Our results show that the genotoxic effect of vanadium can be produced by any of its three oxidation states. However, vanadium(IV) induces double-strand breaks, and it is known that these lesions are linked with forming structural chromosomal aberrations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    NASA Astrophysics Data System (ADS)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

    2016-03-01

    The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks' solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

  18. Structure of dental gallium alloys.

    PubMed

    Herø, H; Simensen, C J; Jørgensen, R B

    1996-07-01

    The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram.

  19. Vanadium exposure-induced striatal learning and memory alterations in rats.

    PubMed

    Sun, Liping; Wang, Keyue; Li, Yan; Fan, Qiyuan; Zheng, Wei; Li, Hong

    2017-09-01

    Occupational and environmental exposure to vanadium has been associated with toxicities in reproductive, respiratory, and cardiovascular systems. The knowledge on whether and how vanadium exposure caused neurobehavioral changes remains incomplete. This study was designed to investigate the changes in learning and memory following drinking water exposure to vanadium, and to conduct the preliminary study on underlying mechanisms. Male Sprague-Dawley rats were exposed to vanadium dissolved in drinking water at the concentration of 0.0, 0.5, 1.0 and 2.0g/L, as the control, low-, medium-, and high- dose groups, respectively, for 12 weeks. The results by the Morris water maze test showed that the time for the testing animal to find the platform in the high exposed group was increased by 82.9% and 49.7%, as compared to animals in control and low-dose groups (p<0.05). There were significantly fewer rats in the medium- and high- dose groups than in the control group who were capable of crossing the platform (p<0.05). Quantitation of vanadium by atomic absorption spectrophotometry revealed a significant dose-dependent accumulation of vanadium in striatum (r=0.931, p<0.01). Histopathological examination further demonstrated a degenerative damage in vanadium-exposed striatum. Interestingly, with the increase of the dose of vanadium, the contents of neurotransmitter ACh, 5-HT and GABA in the striatum increased; however, the levels of Syn1 was significantly reduced in the exposed groups compared with controls (p<0.05). These data suggest that vanadium exposure apparently reduces the animals' learning ability. This could be due partly to vanadium's accumulation in striatum and the ensuing toxicity to striatal structure and synaptic plasticity. Further research is warranted for mechanistic understanding of vanadium-induced neurotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Pharmacokinetics of vanadium in humans after intravenous administration of a vanadium containing albumin solution

    PubMed Central

    Heinemann, Günter; Fichtl, Burckhard; Vogt, Wolfgang

    2003-01-01

    Aims Vanadium is currently undergoing clinical trials as an oral drug in patients with noninsulin-dependent diabetes mellitus. Furthermore, vanadium occurs in elevated concentrations in the blood of patients receiving intravenous albumin solutions containing large amounts of the metal ion as an impurity. The present study was performed to examine the pharmacokinetics of vanadium in humans following a single intravenous (i.v.) dose of a commercial albumin solution containing a high amount of vanadium. Methods The study was conducted in five healthy volunteer subjects who received intravenously 90 ml of a commercial 20% albumin infusion solution containing 47.6 µg vanadium as an impurity. Vanadium concentrations in serum and urine were determined by electrothermal atomic absorption spectrometry. Results Vanadium serum concentrations after i.v. administration were measured for 31 days. The data could be fitted by a triexponential function corresponding formally to a three-compartment model. There was an initial rapid decrease in serum concentrations with half-lives of 1.2 and 26 h. This was followed by a long-terminal half-life time of 10 days. The terminal phase accounted for about 80% of the total area under the serum concentration-time curve (AUC). The mean apparent volume of distribution of the central compartment was found to be 10 l. The volume of distribution at steady state was 54 l, and total clearance was 0.15 l h−1. Vanadium was mainly excreted by the kidneys. About 52% of the dose was recovered in the urine after 12 days. Conclusions This study provides data on vanadium pharmacokinetics in healthy humans. PMID:12630973

  1. An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite.

    PubMed

    Chen, Desheng; Zhao, Hongxin; Hu, Guoping; Qi, Tao; Yu, Hongdong; Zhang, Guozhi; Wang, Lina; Wang, Weijing

    2015-08-30

    An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30-40°C for 10min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0-0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H2SO4 as the stripping agent and under optimal stripping conditions (i.e., 20% H2SO4 concentration, 5:1 phase ratio (O/A), 20min stripping time, and 40°C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16g/LV2O5,0.691g/L Fe, 0.007g/L TiO2, 0.006g/L SiO2 and 0.247g/L CaO. A V2O5 product with a purity of 99.12% V2O5 and only 0.026% Fe was obtained after the oxidation, precipitation, and calcination processes. The total vanadium recovered from the hydrochloric acid leaching solution was 85.5%. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

    NASA Astrophysics Data System (ADS)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-01-01

    Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

  3. An Ultrastable Heterobimetallic Uranium(IV)/Vanadium(III) Solid Compound Protected by a Redox-Active Phosphite Ligand: Crystal Structure, Oxidative Dissolution, and First-Principles Simulation.

    PubMed

    Gui, Daxiang; Dai, Xing; Zheng, Tao; Wang, Xiangxiang; Silver, Mark A; Chen, Lanhua; Zhang, Chao; Diwu, Juan; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

    2018-02-05

    The first heterobimetallic uranium(IV)/vanadium(III) phosphite compound, Na 2 UV 2 (HPO 3 ) 6 (denoted as UVP), was synthesized via an in situ redox-active hydrothermal reaction. It exhibits superior hydrolytic and antioxidant stability compared to the majority of structures containing low-valent uranium or vanadium, further elucidated by first-principles simulations, and therefore shows potential applications in nuclear waste management.

  4. The effect of nitrogen on precipitation and transformation kinetics in vanadium steels

    NASA Astrophysics Data System (ADS)

    Balliger, N. K.; Honeycombe, R. W. K.

    1980-03-01

    The isothermal decomposition of austenite has been studied in a series of vanadium steels containing varying amounts of carbon and nitrogen, (in approximately stoichio-metric proportions), in the temperature range 700 to 850°C. In the basic alloy, Fe-0.27V-0.05C (composition in wt pct), below 810°C the austenite to polygonal ferrite trans-formation is accompanied by interphase precipitation of vanadium carbide, the finer dis-persions being associated with the lower transformation temperatures. However, below 760°C there is an additional precipitation reaction where dislocation precipitation of vanadium carbide predominates; this is shown to occur in association with Widmanstätten ferrite. Above 810° C, a proeutectoid ferrite reaction results, the ferrite being void of precipitates; evidence is provided to show that partitioning of vanadium from ferrite to austenite occurs during the transformation. In the two steels containing nitrogen, namely Fe-0.26V-0.022N-0.020C and Fe-0.29V-0.032 N the basic interphase precipitation re-action is unchanged, but the resultant precipitate dispersions are finer at a given trans-formation temperature. The temperature range over which interphase precipitation oc-curs is expanded by the presence of nitrogen, since the Widmanstätten start tempera-ture is depressed and the proeutectoid ferrite reaction is inhibited. Precipitation in austenite prior to transformation and twin formation during transformation are both en-couraged by the presence of nitrogen.

  5. Novel hybrid materials based on the vanadium oxide nanobelts

    NASA Astrophysics Data System (ADS)

    Zabrodina, G. S.; Makarov, S. G.; Kremlev, K. V.; Yunin, P. A.; Gusev, S. A.; Kaverin, B. S.; Kaverina, L. B.; Ketkov, S. Yu.

    2016-04-01

    Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V2O5·nH2O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB - cetyltrimethylammonium bromide, TBAB - tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA)0.33V2O5 flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA)0.33V2O5, (TBA)0.16V2O5 nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

  6. Rough titanium alloys regulate osteoblast production of angiogenic factors.

    PubMed

    Olivares-Navarrete, Rene; Hyzy, Sharon L; Gittens, Rolando A; Schneider, Jennifer M; Haithcock, David A; Ullrich, Peter F; Slosar, Paul J; Schwartz, Zvi; Boyan, Barbara D

    2013-11-01

    Polyether-ether-ketone (PEEK) and titanium-aluminum-vanadium (titanium alloy) are used frequently in lumbar spine interbody fusion. Osteoblasts cultured on microstructured titanium generate an environment characterized by increased angiogenic factors and factors that inhibit osteoclast activity mediated by integrin α2β1 signaling. It is not known if this is also true of osteoblasts on titanium alloy or PEEK. The purpose of this study was to determine if osteoblasts generate an environment that supports angiogenesis and reduces osteoclastic activity when grown on smooth titanium alloy, rough titanium alloy, or PEEK. This in vitro study compared angiogenic factor production and integrin gene expression of human osteoblast-like MG63 cells cultured on PEEK or titanium-aluminum-vanadium (titanium alloy). MG63 cells were grown on PEEK, smooth titanium alloy, or rough titanium alloy. Osteogenic microenvironment was characterized by secretion of osteoprotegerin and transforming growth factor beta-1 (TGF-β1), which inhibit osteoclast activity and angiogenic factors including vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2), and angiopoietin-1 (ANG-1). Expression of integrins, transmembrane extracellular matrix recognition proteins, was measured by real-time polymerase chain reaction. Culture on titanium alloy stimulated osteoprotegerin, TGF-β1, VEGF-A, FGF-2, and angiopoietin-1 production, and levels were greater on rough titanium alloy than on smooth titanium alloy. All factors measured were significantly lower on PEEK than on smooth or rough titanium alloy. Culture on titanium alloy stimulated expression of messenger RNA for integrins that recognize Type I collagen in comparison with PEEK. Rough titanium alloy stimulated cells to create an osteogenic-angiogenic microenvironment. The osteogenic-angiogenic responses to titanium alloy were greater than PEEK and greater on rough titanium alloy than on smooth titanium alloy. Surface

  7. Vanadium exposure-induced striatal learning and memory alterations in rats

    PubMed Central

    Sun, Liping; Wang, Keyue; Li, Yan; Fan, Qiyuan; Zheng, Wei; Li, Hong

    2017-01-01

    Occupational and environmental exposure to vanadium has been associated with toxicities in reproductive, respiratory, and cardiovascular systems. The knowledge on whether and how vanadium exposure caused neurobehavioral changes remains incomplete. This study was designed to investigate the changes in learning and memory following drinking water exposure to vanadium, and to conduct the preliminary study on underlying mechanisms. Male Sprague-Dawley rats were exposed to vanadium dissolved in drinking water at the concentration of 0.0, 0.5, 1.0 and 2.0 g/L, as the control, low-, medium-, and high- dose groups, respectively, for 12 weeks. The results by the Morris water maze test showed that the time for the testing animal to find the platform in the high exposed group was increased by 82.9% and 49.7%, as compared to animals in control and low-dose groups (p <0.05). There were significantly fewer rats in the medium- and high- dose groups than in the control group who were capable of crossing the platform (p <0.05). Quantitation of vanadium by atomic absorption spectrophotometry revealed a significant dose-dependent accumulation of vanadium in striatum (r = 0.931, p <0.01). Histopathological examination further demonstrated a degenerative damage in vanadium-exposed striatum. Interestingly, with the increase of the dose of vanadium, the contents of neurotransmitter ACh, 5-HT and GABA in the striatum increased; however, the levels of Syn1 was significantly reduced in the exposed groups compared with controls (p <0.05). These data suggest that vanadium exposure apparently reduces the animals’ learning ability. This could be due partly to vanadium’s accumulation in striatum and the ensuing toxicity to striatal structure and synaptic plasticity. Further research is warranted for mechanistic understanding of vanadium-induced neurotoxicity. PMID:28625925

  8. Doping of vanadium to nanocrystalline diamond films by hot filament chemical vapor deposition

    PubMed Central

    2012-01-01

    Doping an impure element with a larger atomic volume into crystalline structure of buck crystals is normally blocked because the rigid crystalline structure could not tolerate a larger distortion. However, this difficulty may be weakened for nanocrystalline structures. Diamonds, as well as many semiconductors, have a difficulty in effective doping. Theoretical calculations carried out by DFT indicate that vanadium (V) is a dopant element for the n-type diamond semiconductor, and their several donor state levels are distributed between the conduction band and middle bandgap position in the V-doped band structure of diamond. Experimental investigation of doping vanadium into nanocrystalline diamond films (NDFs) was first attempted by hot filament chemical vapor deposition technique. Acetone/H2 gas mixtures and vanadium oxytripropoxide (VO(OCH2CH2CH3)3) solutions of acetone with V and C elemental ratios of 1:5,000, 1:2,000, and 1:1,000 were used as carbon and vanadium sources, respectively. The resistivity of the V-doped NDFs decreased two orders with the increasing V/C ratios. PMID:22873631

  9. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    NASA Astrophysics Data System (ADS)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-05-01

    The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V2O5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V2O5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V2O5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/VxOx composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V2O5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing aid, such as the two cysteine-constrained peptides on the phage surface, and has potential for use in nanotechnology applications.

  10. Transformation and precipitation in vanadium treated steels

    NASA Astrophysics Data System (ADS)

    Vassiliou, Andreas D.

    A series of carbon manganese steels containing varying amounts of carbon, vanadium and nitrogen was investigated in relation to the solubility of VC and VN in austenite, the grain coarsening characteristics of austenite, the tempering of martensite and other structures, the transformation during continuous cooling, the effect of vanadium addition and increasing nitrogen content on the thermo-mechanical processing of austenite, and the transformation of various morphologies of austenite to ferrite.The sites for preferential nucleation and growth of ferrite were identified and the effect of ferrite grain size inhomogeneity was investigated with a view to minimising it.The C/N ratio in the V(CN) precipitates was largely controlled by C/N ratio in the steel and it was also influenced by the austenitising treatment. As expected, the solubility of VN was less than that of VC.A systematic investigation of austenitising time and temperature on the grain coarsening characteristics was carried out showing the effects of vanadium, carbon and nitrogen. It was tentatively suggested that C-C and N-N clustering in the vanadium free steels controlled the grain growth whereas in the presence of vanadium, it was shown that VN and VC pinned the austenite grain boundaries and restricted grain growth. However coarsening or solution of VC and VN allowed the grain bondaries to migrate and grain coarsening occurred. The grain coarsening temperature was controlled predominantly by VN, whilst the VC dissolved frequently below the grain coarsening temperature.In the as quenched martensite, increasing nitrogen progressively increased the as quenched hardness, and the hardness also greatly increased with increasing carbon and vanadium added together. Examining the precipitation strengthening in tempered martensite showed that in the absence of vanadium, martensite softened progressively with increasing temperature and time. Vanadium additions increased the hardness level during low temperature

  11. Syntheses, structures and characterizations of three novel vanadium selenites with organically bonded copper/nickel complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qian, Cheng; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002; Kong, Fang

    2016-06-15

    A series of vanadium selenites covalently bonded with metal-organic complex, namely, Ni(2,2-bipy){sub 2}V{sub 2}O{sub 4}(SeO{sub 3}){sub 2} (1), Cu(2,2-bipy)V{sub 2}O{sub 4}(SeO{sub 3}){sub 2}·0.5H{sub 2}O (2) and Cu{sub 2}(2,2-bipy){sub 2}V{sub 5}O{sub 12}(SeO{sub 3}){sub 2} (3) (2,2-bipy=2,2-bipyridine) have been hydrothermally synthesized and structurally characterized. They exhibit three different structural dimensions, from 0D cluster, 1D chain to 2D layer. Compound 1 features a 0D {Ni(2,2-bipy)_2V_2O_4(SeO_3)_2}{sub 2} dimeric cluster composed of two {Ni(2,2-bipy)_2}{sup 2+} moieties connected by the {V_4O_8(SeO_3)_4}{sup 4-} cluster. Compound 2 shows a 1D {Cu(2,2-bipy)V_2O_4(SeO_3)_2}{sub n} chain in which the {Cu_2(2,2-bipy)_2}{sup 4+} moieties are bridged by the {V_4O_8(SeO_3)_4}{sup 4−} clusters. Compound 3more » displays a 2D structure consisted of mixed valence vanadium selenites layers {V"I"VV"V_4Se"I"V_2O_1_8}{sub n}{sup 4−} and {Cu(2,2-bipy)}{sup 2+} complex moieties. The adjacent layers are further interconnected via π-π interactions between the 2,2-bipy ligands exhibiting an interesting 3D supramolecular architecture. Both compound 1 and 2 contain a new {V_4O_8(SeO_3)_4}{sup 4−} cluster and compound 3 exhibits the first 2D vanadate polyhedral layer in vanadium selenites/tellurites with organic moieties. - Graphical abstract: We got three new vanadium selenites with organically linked copper/nickel complex, namely, Ni(2,2-bipy){sub 2}V{sub 2}O{sub 4}(SeO{sub 3}){sub 2} (1), Cu(2,2-bipy)V{sub 2}O{sub 4}(SeO{sub 3}){sub 2}·0.5H{sub 2}O (2) and Cu{sub 2}(2,2-bipy){sub 2}V{sub 5}O{sub 12}(SeO{sub 3}){sub 2} (3) by hydrothermally syntheses. They display three different structural dimensions, from 0D cluster, to 1D chain and 2D layer. Display Omitted - Highlights: • Three new compounds display three different structural dimensions, from 0D cluster, to 1D chain and 2D layer. • The Tetranuclear {V_4O_8(SeO_3)_4}{sup 4−} cluster and the

  12. Structure-property relationship of cast Ti-Nb alloys.

    PubMed

    Lee, C M; Ju, C P; Chern Lin, J H

    2002-04-01

    The present work is a study of the microstructure, mechanical properties and corrosion behaviour of a series of binary Ti-Nb alloys with Nb contents up to 35 wt%, with emphasis placed on the structure-property relationship of the alloys. The results indicate that crystal structure and morphology of the Ti-Nb alloys are sensitive to the Nb content. The cast c.p. Ti has a hexagonal alpha phase with a lath type morphology. The alloys containing 15 wt% or less Nb are dominated by a hexagonal alpha' phase with an acicular, martensitic structure. When containing 17.5-25 wt% Nb, the alloys are primarily comprised of an orthorhombic alpha" phase. With 27.5 wt% Nb, metastable beta phase starts to be retained. With Nb contents higher than 30 wt%, the equi-axed beta phase is almost entirely retained. Small amounts of omega phase are detected in alloys containing 27.5 and 30 wt% Nb. Among all present alloys, Ti-10Nb and Ti-27.5Nb exhibit the highest strengths, while the alpha"-dominated (17.5 and 20Nb) and beta-dominated (> 30Nb) alloys have the lowest moduli. All Ti-Nb alloys show excellent corrosion resistance in Hank's solution at 37 degrees C. From the present data, the microhardness, bending strength and modulus of the various phases in Ti-Nb alloys are compared and tentatively summarized as follows: Microhardness: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending strength: omega > alpha' > alpha" > beta > alpha (c.p. Ti) Bending modulus: omega > alpha (c.p. Ti) > alpha' > alpha" > beta

  13. Effectively suppressing vanadium permeation in vanadium redox flow battery application with modified Nafion membrane with nacre-like nanoarchitectures

    NASA Astrophysics Data System (ADS)

    Zhang, Lesi; Ling, Ling; Xiao, Min; Han, Dongmei; Wang, Shuanjin; Meng, Yuezhong

    2017-06-01

    A novel self-assembled composite membrane, Nafion-[PDDA/ZrP]n with nacre-like nanostructures was successfully fabricated by a layer-by-layer (LbL) method and used as proton exchange membrane for vanadium redox flow battery applications. Poly(diallyldimethylammonium chloride) (PDDA) with positive charges and zirconium phosphate (ZrP) nanosheets with negative charges can form ultra-thin nacre-like nanostructure on the surface of Nafion membrane via the ionic crosslinking of tightly folded macromolecules. The lamellar structure of ZrP nanosheets and Donnan exclusion effect of PDDA can greatly decrease the vanadium ion permeability and improve the selectivity of proton conductivity. The fabricated Nafion-[PDDA/ZrP]4 membrane shows two orders of magnitude lower vanadium ion permeability (1.05 × 10-6 cm2 min-1) and 12 times higher ion selectivity than those of pristine Nafion membrane at room temperature. Consequently, the performance of vanadium redox flow batteries (VRFBs) assembled with Nafion-[PDDA/ZrP]3 membrane achieved a highly coulombic efficiency (CE) and energy efficiency (EE) together with a very slow self-discharge rate. When comparing with pristine Nafion VRFB, the CE and EE values of Nafion-[PDDA/ZrP]3 VRFB are 10% and 7% higher at 30 mA cm-2, respectively.

  14. Electrochemical cell structure including an ionomeric barrier

    DOEpatents

    Lambert, Timothy N.; Hibbs, Michael

    2017-06-20

    An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

  15. Effect of Sulfuric and Triflic Acids on the Hydration of Vanadium Cations: An ab Initio Study.

    PubMed

    Sepehr, Fatemeh; Paddison, Stephen J

    2015-06-04

    Vanadium redox flow batteries (VRFBs) may be a promising solution for large-scale energy storage applications, but the crossover of any of the redox active species V(2+), V(3+), VO(2+), and VO2(+) through the ion exchange membrane will result in self-discharge of the battery. Hence, a molecular level understanding of the states of vanadium cations in the highly acidic environment of a VRFB is needed. We examine the effects of sulfuric and triflic (CF3SO3H) acids on the hydration of vanadium species as they mimic the electrolyte and functional group of perfluorosulfonic acid (PFSA) membranes. Hybrid density functional theory in conjunction with a continuum solvation model was utilized to obtain the local structures of the hydrated vanadium cations in proximity to H2SO4, CF3SO3H, and their conjugate anions. The results indicate that none of these species covalently bond to the vanadium cations. The hydration structure of V(3+) is more distorted than that of V(2+) in an acidic medium. The oxo-group of VO2(+) is protonated by either acid, in contrast to VO(2+) which is not protonated. The atomic partial charge of the four oxidation states of vanadium varies from +1.7 to +2.0. These results provide the local solvation structures of vanadium cations in the VRFBs environment that are directly related to the electrolytes stability and diffusion of vanadium ions into the membrane.

  16. Subtask 12B1: Welding development for V-Cr-Ti alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    King, J.F.; Goodwin, G.M.; Grossbeck, M.L.

    1995-03-01

    Development of the metallurgical and technological basis for the welding of thick sections of V-Cr-Ti alloys. The weldability and weldment properties of the V-5Cr-5Ti alloy have been evaluated. Results for the Sigmajig test of the vanadium alloy were similar to the cracking resistance of stainless steels, and indicates hot-cracking is unlikely to be a problem. Subsize Charpy test results for GTA weld metal in the as-welded condition have shown a significant reduction in toughness compared to the base metal. The weld metal toughness properties were restored to approximately that of the base metal after exposure to a PWHT 950{degrees}C. Themore » subsize Charpy toughness results for the EB weld metal from this same heat of vanadium alloy has shown significant improvement in properties compared to the GTA weld metal and the base metal. Further testing and analysis will be conducted to more fully characterize the properties of weld metal for each welding process and develop a basic understanding of the cause of the toughness decrease in the GTA welds. 5 figs., 1 tab.« less

  17. Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

    PubMed

    Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

    2008-11-01

    Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

  18. A method for recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-min; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

    2018-02-01

    An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

  19. Key structure-activity relationships in the vanadium phosphorus oxide catalyst system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thompson, M.R.; Ebner, J.R.

    1990-04-01

    The crystal structure of vanadyl pyrophosphate has been redetermined using single crystals obtained from a near solidified melt of a microcrystalline catalyst sample. Crystals that index as vanadyl pyrophosphate obtained from this melt are variable in color. Crystallographic refinement of the single crystal x-ray diffraction data indicates that structural differences among these materials can be described in terms of crystal defects associated with linear disorder of the vanadium atoms. The importance of the disorder is outlined in the context of its effect on the proposed surface topology parallel to (1,0,0). Models of the surface topology simply and intuitively account formore » the non-stoichometric surface atomic P/V ratio exhibited by selective catalysts of this phase. These models also point to the possible role of the excess phosphorus in providing site isolation of reactive centers at the surface. 33 refs., 7 figs.« less

  20. The fabrication and visible-near-infrared optical modulation of vanadium dioxide/silicon dioxide composite photonic crystal structure

    NASA Astrophysics Data System (ADS)

    Liang, Jiran; Li, Peng; Song, Xiaolong; Zhou, Liwei

    2017-12-01

    We demonstrated a visible and near-infrared light tunable photonic nanostructure, which is composed of vanadium dioxide (VO2) thin film and silicon dioxide (SiO2) ordered nanosphere arrays. The vanadium films were sputtered on two-dimensional (2D) SiO2 sphere arrays. VO2 thin films were prepared by rapid thermal annealing (RTA) method with different oxygen flow rates. The close-packed VO2 shell formed a continuous surface, the composition of VO2 films in the structure changed when the oxygen flow rates increased. The 2D VO2/SiO2 composite photonic crystal structure exhibited transmittance trough tunability and near-infrared (NIR) transmittance modulation. When the oxygen flow rate increased from 3 slpm to 4 slpm, the largest transmittance trough can be regulated from 904 to 929 nm at low temperature, the transmittance troughs also appear blue shift when the VO2 phase changes from insulator to metal. The composite nanostructure based on VO2 films showed visible transmittance tunability, which would provide insights into the glass color changing in smart windows.

  1. Effect of transition metal impurities on the strength of grain boundaries in vanadium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Xuebang; Kong, Xiang-Shan; You, Yu-Wei

    2016-09-07

    Effects of 3d (Ti-Ni), 4d (Zr-Pd), and 5d (Hf-Pt) transition metal impurities on strength of two representative vanadium grain boundaries (GBs), symmetric Σ3(111) and asymmetric Σ5(210), were studied by first-principles calculations within the framework of the Rice-Wang thermodynamic model and within the computational tensile test. The desirable elements to increase the GB cohesion were predicted based on their segregation and strengthening behaviors across the different GB sites. It reveals that the elements Ti, Zr, Hf, Nb, and Ta are good choices for the GB cohesion enhancers. In addition, the GB strengthening by solutes is sensitive to the GB structures. Themore » elements Cr, Mn, Fe, Co, and Ni decrease the GB strength of the Σ3(111) GB but they can increase the cohesion of the Σ5(210) GB. Furthermore, the origin of Ti-induced change of the GB strength was uncovered by analyzing the atomic bonds and electronic structures as well as the tensile strength. This work provides a theoretical guidance to screen promising alloying elements in V-based materials with improved resistance to GB decohesion and also helps us to understand the formation mechanism of Ti-rich precipitates in the V-Cr-Ti alloys under neutron or ion irradiation environments.« less

  2. Nickel aluminide alloy suitable for structural applications

    DOEpatents

    Liu, Chain T.

    1998-01-01

    Alloys for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1.+-.0.8%)Al--(1.0.+-.0.8%)Mo--(0.7.+-.0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques.

  3. [Oxidative Stress Level of Vanadium-exposed Workers].

    PubMed

    Wei, Teng-da; Li, Shun-pin; Liu, Yun-xing; Tan, Chun-ping; Li, Juan; Zhang, Zu-hui; Lan, Ya-jia; Zhang, Qin

    2015-11-01

    To determine the oxidative stress level in peripheral blood of vanadium-exposed workers, as an indication of population health effect of vanadium on human neurobehavioral system. 86 vanadium-exposed workers and 65 non-exposed workers were recruited by cluster sampling. A questionnaire was administered to collect demographic and occupational exposure information. Serum activity of superoxide dismutase (SOD), inducible nitric oxide synthase (iNOS) and malonaldehyde (MDA) contents were detected by kit assay. The differences in oxidative stress level between vanadium-exposed and non-exposed workers were compared. Vanadium-exposed workers had higher levels of MDA contents than the controls. The total superoxide dismutase(T-SOD) activity in vanadium-exposed workers was significantly lower than that in the controls, which was associated with lowered levels of manganese superoxide dismutase (Mn-SOD) activity. No changes in serum levels of cupro-zinc superoxide dismutase (CuZn-SOD) was found in vanadium-exposed workers. No difference in iNOS activity was found between vanadium-exposed workers and controls. Vanadium exposure increases free radical production in serum and reduces antioxidant capacity. But the relationship between vanadium exposure and iNOS damage remains uncertain.

  4. Electrical and Infrared Optical Properties of Vanadium Oxide Semiconducting Thin-Film Thermometers

    NASA Astrophysics Data System (ADS)

    Zia, Muhammad Fakhar; Abdel-Rahman, Mohamed; Alduraibi, Mohammad; Ilahi, Bouraoui; Awad, Ehab; Majzoub, Sohaib

    2017-10-01

    A synthesis method has been developed for preparation of vanadium oxide thermometer thin film for microbolometer application. The structure presented is a 95-nm thin film prepared by sputter-depositing nine alternating multilayer thin films of vanadium pentoxide (V2O5) with thickness of 15 nm and vanadium with thickness of 5 nm followed by postdeposition annealing at 300°C in nitrogen (N2) and oxygen (O2) atmospheres. The resulting vanadium oxide (V x O y ) thermometer thin films exhibited temperature coefficient of resistance (TCR) of -3.55%/°C with room-temperature resistivity of 2.68 Ω cm for structures annealed in N2 atmosphere, and TCR of -3.06%/°C with room-temperature resistivity of 0.84 Ω cm for structures annealed in O2 atmosphere. Furthermore, optical measurements of N2- and O2-annealed samples were performed by Fourier-transform infrared ellipsometry to determine their dispersion curves, refractive index ( n), and extinction coefficient ( k) at wavelength from 7000 nm to 14,000 nm. The results indicate the possibility of applying the developed materials in thermometers for microbolometers.

  5. Vanadium distribution in rats and DNA cleavage by vanadyl complex: implication for vanadium toxicity and biological effects.

    PubMed Central

    Sakurai, H

    1994-01-01

    Vanadium ion is toxic to animals. However, vanadium is also an agent used for chemoprotection against cancers in animals. To understand both the toxic and beneficial effects we studied vanadium distribution in rats. Accumulation of vanadium in the liver nuclei of rats given low doses of compounds in the +4 or +5 oxidation state was greater than in the liver nuclei of rats given high doses of vanadium compounds or the vanadate (+5 oxidation state) compound. Vanadium was incorporated exclusively in the vanadyl (+4 oxidation state) form. We also investigated the reactions of vanadyl ion and found that incubation of DNA with vanadyl ion and hydrogen peroxide (H2O2) led to intense DNA cleavage. ESR spin trapping demonstrated that hydroxyl radicals are generated during the reactions of vanadyl ion and H2O2. Thus, we propose that the mechanism for vanadium-dependent toxicity and antineoplastic action is due to DNA cleavage by hydroxyl radicals generated in living systems. PMID:7843133

  6. Synthesis, characterization, X-ray crystal structure, DFT calculation and antibacterial activities of new vanadium(IV, V) complexes containing chelidamic acid and novel thiourea derivatives.

    PubMed

    Farzanfar, Javad; Ghasemi, Khaled; Rezvani, Ali Reza; Delarami, Hojat Samareh; Ebrahimi, Ali; Hosseinpoor, Hona; Eskandari, Amir; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2015-06-01

    Three new thiourea ligands derived from the condensation of aroyl- and aryl-isothiocyanate derivatives with 2,6-diaminopyridine, named 1,1'-(pyridine-2,6-diyl)bis(3-(benzoyl)thiourea) (L1), 1,1'-(pyridine-2,6-diyl)bis(3-(2-chlorobenzoyl)thiourea) (L2) and 1,1'-(pyridine-2,6-diyl)bis(3-(4-chlorophenyl)thiourea) (L3), their oxido-vanadium(IV) complexes, namely [VO(L1('))(H2O)] (C1), [VO(L2('))(H2O)] (C2) and [VO(L3('))(H2O)] (C3), and also, dioxo-vanadium(V) complex containing 4-hydroxy-2,6-pyridine dicarboxylic acid (chelidamic acid, H2dipic-OH) and metformin (N,N-dimethylbiguanide, Met), named [H2Met][VO2(dipic-OH)]2·H2O (C4), were synthesized and characterized by elemental analysis, FTIR and (1)H NMR and UV-visible spectroscopies. Proposed structures for free thiourea ligands and their vanadium complexes were corroborated by applying geometry optimization and conformational analysis. Solid state structure of complex [H2Met][VO2(dipic-OH)]2·H2O (triclinic, Pī) was fully determined by single crystal X-ray diffraction analysis. In this complex, metformin is double protonated and acted as counter ion. The antibacterial properties of these compounds were investigated in vitro against standard Gram-positive and Gram-negative bacterial strains. The experiments showed that vanadium(IV) complexes had the superior antibacterial activities than novel thiourea derivatives and vanadium(V) complex against all Gram-positive and Gram-negative bacterial strains. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

    NASA Astrophysics Data System (ADS)

    de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

    2006-12-01

    HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

  8. Nickel aluminide alloy suitable for structural applications

    DOEpatents

    Liu, C.T.

    1998-03-10

    Alloys are disclosed for use in structural applications based upon NiAl to which are added selected elements to enhance room temperature ductility and high temperature strength. Specifically, small additions of molybdenum produce a beneficial alloy, while further additions of boron, carbon, iron, niobium, tantalum, zirconium and hafnium further improve performance of alloys at both room temperature and high temperatures. A preferred alloy system composition is Ni--(49.1{+-}0.8%)Al--(1.0{+-}0.8%)Mo--(0.7 + 0.5%)Nb/Ta/Zr/Hf--(nearly zero to 0.03%)B/C, where the % is at. % in each of the concentrations. All alloys demonstrated good oxidation resistance at the elevated temperatures. The alloys can be fabricated into components using conventional techniques. 4 figs.

  9. Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching

    NASA Astrophysics Data System (ADS)

    Li, Meng; Du, Hao; Zheng, Shili; Wang, Shaona; Zhang, Yang; Liu, Biao; Dreisinger, David Bruce; Zhang, Yi

    2017-10-01

    A clean method featuring non-salt roasting followed by (NH4)2C2O4 leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr6+ compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH4)2C2O4 solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH4)2C2O4 at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined.

  10. Effect of S-doping on structural, optical and electrochemical properties of vanadium oxide thin films prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Mousavi, M.; Kompany, A.; Shahtahmasebi, N.; Bagheri-Mohagheghi, M.-M.

    2013-12-01

    In this research, S-doped vanadium oxide thin films, with doping levels from 0 to 40 at.%, are prepared by spray pyrolysis technique on glass substrates. For electrochemical measurements, the films were deposited on florin-tin oxide coated glass substrates. The effect of S-doping on structural, electrical, optical and electrochemical properties of vanadium oxide thin films was studied. The x-ray diffractometer analysis indicated that most of the samples have cubic β-V2O5 phase structure with preferred orientation along [200]. With increase in the doping levels, the structure of the samples tends to be amorphous. The scanning electron microscopy images show that the structure of the samples is nanobelt-shaped and the width of the nanobelts decreases from nearly 100 to 40 nm with increase in the S concentration. With increase in the S-doping level, the sheet resistance and the optical band gap increase from 940 to 4015 kΩ/square and 2.41 to 2.7 eV, respectively. The cyclic voltammogram results obtained for different samples show that the undoped sample is expanded and the sample prepared at 20 at.% S-doping level has sharper anodic and cathodic peaks.

  11. Periodic Cellular Structure Technology for Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Chen, Edward Y.

    2015-01-01

    Shape memory alloys are being considered for a wide variety of adaptive components for engine and airframe applications because they can undergo large amounts of strain and then revert to their original shape upon heating or unloading. Transition45 Technologies, Inc., has developed an innovative periodic cellular structure (PCS) technology for shape memory alloys that enables fabrication of complex bulk configurations, such as lattice block structures. These innovative structures are manufactured using an advanced reactive metal casting technology that offers a relatively low cost and established approach for constructing near-net shape aerospace components. Transition45 is continuing to characterize these structures to determine how best to design a PCS to better exploit the use of shape memory alloys in aerospace applications.

  12. Computing elastic anisotropy to discover gum-metal-like structural alloys

    NASA Astrophysics Data System (ADS)

    Winter, I. S.; de Jong, M.; Asta, M.; Chrzan, D. C.

    2017-08-01

    The computer aided discovery of structural alloys is a burgeoning but still challenging area of research. A primary challenge in the field is to identify computable screening parameters that embody key structural alloy properties. Here, an elastic anisotropy parameter that captures a material's susceptibility to solute solution strengthening is identified. The parameter has many applications in the discovery and optimization of structural materials. As a first example, the parameter is used to identify alloys that might display the super elasticity, super strength, and high ductility of the class of TiNb alloys known as gum metals. In addition, it is noted that the parameter can be used to screen candidate alloys for shape memory response, and potentially aid in the optimization of the mechanical properties of high-entropy alloys.

  13. Structural transformations of heat treated Co-less high entropy alloys

    NASA Astrophysics Data System (ADS)

    Mitrica, D.; Tudor, A.; Rinaldi, A.; Soare, V.; Predescu, C.; Berbecaru, A.; Stoiciu, F.; Badilita, V.

    2018-03-01

    Co is considered to be one of the main ingredients in superalloys. Co is considered a critical element and its substitution is difficult due to its unique ability to form high temperature stable structures with high mechanical and corrosion/oxidation resistance. High entropy alloys (HEA) represent a relatively new concept in material design. HEA are characterised by a high number of alloying elements, in unusually high proportion. Due to their specific particularities, high entropy alloys tend to form predominant solid solution structures that develop potentially high chemical, physical and mechanical properties. Present paper is studying Co-less high entropy alloys with high potential in severe environment applications. The high entropy alloys based on Al-Cr-Fe-Mn-Ni system were prepared by induction melting and casting under protective atmosphere. The as-cast specimens were heat treated at various temperatures to determine the structure and property behaviour. Samples taken before and after heat treatment were investigated for chemical, physical, structural and mechanical characteristics. Sigma phase composition and heat treatment parameters had major influence over the resulted alloy structure and properties.

  14. Effects of dietary vanadium in mallard ducks

    USGS Publications Warehouse

    White, D.H.; Dieter, M.P.

    1978-01-01

    Adult mallard ducks fed 0, 1, 10, or 100 ppm vanadyl sulfate in the diet were sacrificed after 12 wk on treatment; tissues were analyzed for vanadium. No birds died during the study and body weights did not change. Vanadium accumulated to higher concentrations in the bone and liver than in other tissues. Concentrations in bones of hens were five times those in bones of drakes, suggesting an interaction between vanadium and calcium mobilization in laying hens. Vanadium concentrations in most tissues were significantly correlated and increased with treatment level. Lipid metabolism was altered in laying hens fed 100 ppm vanadium. Very little vanadium accumulated in the eggs of laying hens.

  15. Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

    NASA Astrophysics Data System (ADS)

    Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

    2013-09-01

    We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

  16. Spatial distribution of vanadium and microbial community responses in surface soil of Panzhihua mining and smelting area, China.

    PubMed

    Cao, Xuelong; Diao, Muhe; Zhang, Baogang; Liu, Hui; Wang, Song; Yang, Meng

    2017-09-01

    Spatial distribution of vanadium in surface soils from different processing stages of vanadium-bearing titanomagnetite in Panzhihua mining and smelting area (China) as well as responses of microbial communities including bacteria and fungi to vanadium were investigated by fieldwork and laboratory incubation experiment. The vanadium contents in this region ranged from 149.3 to 4793.6 mg kg -1 , exceeding the soil background value of vanadium in China (82 mg kg -1 ) largely. High-throughput DNA sequencing results showed bacterial communities from different manufacturing locations were quite diverse, but Bacteroidetes and Proteobacteria were abundant in all samples. The contents of organic matter, available P, available S and vanadium had great influences on the structures of bacterial communities in soils. Bacterial communities converged to similar structure after long-term (240 d) cultivation with vanadium containing medium, dominating by bacteria which can tolerate or reduce toxicities of heavy metals. Fungal diversities decreased after cultivation, but Ascomycota and Ciliophora were still the most abundant phyla as in the original soil samples. Results in this study emphasize the urgency of investigating vanadium contaminations in soils and provide valuable information on how vanadium contamination influences bacterial and fungal communities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Release kinetics of vanadium from vanadium (III, IV and V) oxides: Effect of pH, temperature and oxide dose.

    PubMed

    Hu, Xingyun; Yue, Yuyan; Peng, Xianjia

    2018-05-01

    Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium (III, IV and V) oxides at pH 3.1-10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V 2 O 5 and vanadium(III, IV) oxides. In the first 2hr, the release rates of vanadium from V 2 O 3 were r=1.14·([H + ]) 0.269 at pH 3.0-6.0 and r=0.016·([H + ]) -0.048 at pH 6.0-10.0; the release rates from VO 2 were r=0.362·([H + ]) 0.129 at pH 3.0-6.0 and r=0.017·([H + ]) -0.097 at pH 6.0-10.0; and the release rates from V 2 O 5 were r=0.131·([H + ]) -0.104 at pH 3.1-10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium (III, IV and V) oxides (33.4-87.5kJ/mol) were determined at pH 3.8, pH6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose, albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment. Copyright © 2017. Published by Elsevier B.V.

  18. Speciation of vanadium in Chinese cabbage (Brassica rapa L.) and soils in response to different levels of vanadium in soils and cabbage growth.

    PubMed

    Tian, Liyan; Yang, Jinyan; Alewell, Christine; Huang, Jen-How

    2014-09-01

    This study highlights the accumulation and speciation of vanadium in Chinese cabbage (Brassica rapa L.) in relation to the speciation of soil vanadium with pot experiments at 122-622mgVkg(-1) by spiking NH4VO3. Cabbage planting decreased the bioavailable and residual vanadium based on sequential extraction, leading to enrichment of oxalate-extractable vanadium in soils. The biomass production increased with increasing concentrations of soil vanadium from 122 to 372mgVkg(-1), probably due to the increasing nitrogen availability and low vanadium availability in our soils with a consequent low vanadium toxicity. Although the concentrations of root vanadium (14.4-24.9mgVkg(-1)) related positively with soil vanadium, the bio-dilution alleviated the increase of leaf vanadium (2.1-2.7mgVkg(-1)). The predominance of vanadium(IV) in leaves (∼60-80% of total vanadium) indicates bio-reduction of vanadium in Chinese cabbage, since the mobile vanadium in oxic soils was usually pentavalent. Approximately 15-20% of the leaf vanadium was associated with recalcitrant leaf tissues. The majority of leaf vanadium was water and ethanol extractable, which is considered mobile and may cause more toxic effects on Chinese cabbage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Structural direction of hybrid organic-inorganic materials: Synthesis of vanadium oxyfluoride, copper vanadate, and copper molybdate solid state materials through solvuthermal and solution methods

    NASA Astrophysics Data System (ADS)

    Deburgomaster, Paul

    The vast structural complexity of inorganic oxides with structure directing organocations, nitrogen containing ligands and organophosphonate ligands was explored. The hydrothermal reaction conditions utilized herein include the variables of temperature, pH, fill volume and stoichiometry. The systems studied included: (1) the complex materials rendered from reactions of organoamine cations on the structure of vanadium oxides, oxyfluorides and fluorides. As with other systems, the influence of the mineralizer HF was not limited to pH as fluorine incorporation was not uncommon. In specific cases this coincided with reduction of vanadium sites. (2) The copper-organonitrogen ligand/vanadium oxide/aromatic phosphonate system has been studied. The rigid aromatic di- and tri-phosphonate tethers have provided a series of materials which are structurally distinct from the previously investigated aliphatic series. The inclusion of copper-coordinated nitrogen bi- and tri-dentate ligands also provided structural diversity. Product composition was highly influenced by the HF/V ratio. A similar study was conducted with the ligand 1,4-carboxy-phenylphosphonic acid. (3) The preparation of a series of bimetallic organic-inorganic hybrid materials of the M(II)/VxOy/organonitrogen ligand class was further evidence of the utility of thermodynamically driven hydrothermal synthesis. (4) While decomposition of the spherical Keplerate molybdenum clusters is encountered under hydrothermal conditions, this highly soluble form of molybdate was investigated for the development of hybrid organic-inorganic room temperature solution synthesis.

  20. Influence of vanadium on serum lipid and lipoprotein profiles: a population-based study among vanadium exposed workers

    PubMed Central

    2014-01-01

    Background Some experimental animal studies reported that vanadium had beneficial effects on blood total cholesterol (TC) and triglyceride (TG). However, the relationship between vanadium exposure and lipid, lipoprotein profiles in human subjects remains uncertain. This study aimed to compare the serum lipid and lipoprotein profiles of occupational vanadium exposed and non-exposed workers, and to provide human evidence on serum lipid, lipoprotein profiles and atherogenic indexes changes in relation to vanadium exposure. Methods This cross-sectional study recruited 533 vanadium exposed workers and 241 non-exposed workers from a Steel and Iron Group in Sichuan, China. Demographic characteristics and occupational information were collected through questionnaires. Serum lipid and lipoprotein levels were measured for all participants. The ratios of total cholesterol to high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) to HDL-C and apoB to apoA-I were used as atherogenic indexes. A general linear model was applied to compare outcomes of the two groups while controlling possible confounders and multivariate logistic regression was performed to evaluate the relationship between low HDL-C level, abnormal atherogenic index and vanadium exposure. Results Higher levels of HDL-C and apoA-I could be observed in the vanadium exposed group compared with the control group (P < 0.05). Furthermore, atherogenic indexes (TC/HDL-C, LDL-C/HDL-C, and apoB/apoA-I ratios) were found statistically lower in the vanadium exposed workers (P < 0.05). Changes in HDL-C, TC/HDL-C, and LDL-C/HDL-C were more pronounced in male workers than that in female workers. In male workers, after adjusting for potential confounding variables as age, habits of smoking and drinking, occupational vanadium exposure was still associated with lower HDL-C (OR 0.41; 95% CI, 0.27-0.62) and abnormal atherogenic index (OR 0.38; 95% CI, 0.20-0.70). Conclusion Occupational

  1. Development of hydrogen resistant structural alloy NASA-23

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.; Mcpherson, W. B.; Kuruvilla, A. K.; Chen, P. S.; Panda, B.

    1993-01-01

    Hydrogen-resistant alloy NASA-23 was developed specifically as a structural alloy for application in liquid propulsion systems that use hydrogen fuel. NASA-23 was designed to be similar to Alloy 718 in strength, ductility, and corrosion resistance, but with superior resistance to hydrogen environment embrittlement. The alloy is readily processed; it can be both hot and cold worked and is castable and weldable. A material property data base is being generated for both cast and wrought NASA-23. This paper will present the status of alloy development and discuss potential applications in propulsion systems.

  2. Solution XAS Analysis for Exploring the Active Species in Homogeneous Vanadium Complex Catalysis

    NASA Astrophysics Data System (ADS)

    Nomura, Kotohiro; Mitsudome, Takato; Tsutsumi, Ken; Yamazoe, Seiji

    2018-06-01

    Selected examples in V K-edge X-ray Absorption Near Edge Structure (XANES) analysis of a series of vanadium complexes containing imido ligands (possessing metal-nitrogen double bond) in toluene solution have been introduced, and their pre-edge and the edge were affected by their structures and nature of ligands. Selected results in exploring the oxidation states of the active species in ethylene dimerization/polymerization using homogeneous vanadium catalysts [consisting of (imido)vanadium(V) complexes and Al cocatalysts] by X-ray absorption spectroscopy (XAS) analyses have been introduced. It has been demonstrated that the method should provide more clear information concerning the active species in situ, especially by combination with the other methods (NMR and ESR spectra, X-ray crystallographic analysis, and reaction chemistry), and should be powerful tool for study of catalysis mechanism as well as for the structural analysis in solution.

  3. Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

    NASA Astrophysics Data System (ADS)

    Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

    2018-06-01

    Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

  4. Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

    NASA Astrophysics Data System (ADS)

    Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

    2018-04-01

    Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

  5. Commercialization of the Chevron FCC vanadium trap

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kennedy, J.V.; Kuehler, C.W.; Krishna, A.S.

    1995-09-01

    Vanadium, present to varying degrees in FCC feed, deposits on the catalyst virtually quantitatively in the cracking process. In resid operations, vanadium levels on catalyst can reach 10,000 ppm at typical catalyst make-up rates. Once on the catalyst, vanadium destroys the zeolite and restricts access to active sites. This reduces catalyst activity. A vanadium trap is a material that when introduced into the catalyst inventory selectively reacts with migrating vanadium, thus protecting the zeolite and other active components of the catalyst. The trap may be incorporated into the catalyst, or introduced as a separate particle. Only a limited amount ofmore » trap can be incorporated into the catalyst without limiting the amount of zeolite that can be included. Gulf began development of a vanadium trap during the early 1980`s. The work produced a variety of promising materials whose use as vanadium traps was subsequently patented. The work ultimately led to a formulation with a phase very active for trapping vanadium while still quite sulfur tolerant. Based on these results, an extensive pilot plant evaluation was undertaken by Chevron after the Chevron-Gulf merger to better simulate commercial operation. The paper describes pilot plant tests as well as 3 commercial tests of this vanadium trap.« less

  6. Vanadium-Binding Ability of Nucleoside Diphosphate Kinase from the Vanadium-Rich Fan Worm, Pseudopotamilla occelata.

    PubMed

    Yamaguchi, Nobuo; Yoshinaga, Masafumi; Kamino, Kei; Ueki, Tatsuya

    2016-06-01

    Polychaete fan worms and ascidians accumulate high levels of vanadium ions. Several vanadiumbinding proteins, known as vanabins, have been found in ascidians. However, no vanadium-binding factors have been isolated from the fan worm. In the present study, we sought to identify vanadiumbinding proteins in the branchial crown of the fan worm using immobilized metal ion affinity chromatography. A nucleoside diphosphate kinase (NDK) homolog was isolated and determined to be a vanadium-binding protein. Kinase activity of the NDK homologue, PoNDK, was suppressed by the addition of V(IV), but was unaffected by V(V). The effect of V(IV) on PoNDK precedes its activation by Mg(II). This is the first report to describe the relationship between NDK and V(IV). PoNDK is located in the epidermis of the branchial crown, and its distribution is very similar to that of vanadium. These results suggest that PoNDK is associated with vanadium accumulation and metabolism in P. occelata.

  7. Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

    NASA Astrophysics Data System (ADS)

    Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

    2018-02-01

    Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

  8. Assessment of Titanium Aluminide Alloys for High-Temperature Nuclear Structural Applications

    NASA Astrophysics Data System (ADS)

    Zhu, Hanliang; Wei, Tao; Carr, David; Harrison, Robert; Edwards, Lyndon; Hoffelner, Wolfgang; Seo, Dongyi; Maruyama, Kouichi

    2012-12-01

    Titanium aluminide (TiAl) alloys exhibit high specific strength, low density, good oxidation, corrosion, and creep resistance at elevated temperatures, making them good candidate materials for aerospace and automotive applications. TiAl alloys also show excellent radiation resistance and low neutron activation, and they can be developed to have various microstructures, allowing different combinations of properties for various extreme environments. Hence, TiAl alloys may be used in advanced nuclear systems as high-temperature structural materials. Moreover, TiAl alloys are good materials to be used for fundamental studies on microstructural effects on irradiation behavior of advanced nuclear structural materials. This article reviews the microstructure, creep, radiation, and oxidation properties of TiAl alloys in comparison with other nuclear structural materials to assess the potential of TiAl alloys as candidate structural materials for future nuclear applications.

  9. [The vanadium compounds: chemistry, synthesis, insulinomimetic properties].

    PubMed

    Fedorova, E V; Buriakina, A V; Vorob'eva, N M; Baranova, N I

    2014-01-01

    The review considers the biological role of vanadium, its participation in various processes in humans and other mammals, and the anti-diabetic effect of its compounds. Vanadium salts have persistent hypoglycemic and antihyperlipidemic effects and reduce the probability of secondary complications in animals with experimental diabetes. The review contains a detailed description of all major synthesized vanadium complexes having antidiabetic activity. Currently, vanadium complexes with organic ligands are more effective and safer than the inorganic salts. Despite the proven efficacy of these compounds as the anti-diabetic agents in animal models, only one organic complex of vanadium is currently under the second phase of clinical trials. All of the considered data suggest that vanadium compound are a new promising class of drugs in modern pharmacotherapy of diabetes.

  10. Effects of thermomechanical processing on strength and toughness of iron - 12-percent-nickel - reactive metal alloys at -196 C

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1978-01-01

    Thermomechanical processing (TMP) was evaluated as a method of strengthening normally tough iron-12-nickel-reactive metal alloys at cryogenic temperatures. Five iron-12 nickel alloys with reactive metal additions of aluminum, niobium, titanium, vanadium, and aluminum plus niobium were investigated. Primary evaluation was based on the yield strength and fracture toughness of the thermomechanically processed alloys at -196 C.

  11. The effect of thermomechanical treatment regimes on microstructure and mechanical properties of V–Me(Cr, W)–Zr–C alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tyumentsev, A. N., E-mail: tyuments@phys.tsu.ru; Ditenberg, I. A.; Grinyaev, K. V.

    2015-12-15

    The regularities of the formation of a heterophase structure in dispersion-strengthened vanadium V–Me(Cr, W)–Zr–C alloys are studied as a function of the regimes of their thermomechanical treatment. The regimes of treatment providing a substantial increase in the dispersity and homogeneity of spatial distribution of ZrC particles, temperature of recrystallization, and high-temperature (at T = 800°C) short-time strength are found in comparison to conventional treatment regimes.

  12. NASA-UVA light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Stoner, Glenn E.; Swanson, Robert E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1990-01-01

    The objective of the Light Aerospace Alloy and Structures Technology Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. Individual technical objectives are established for each project. Efforts aim to produce basic understanding of material behavior, monolithic and composite alloys, processing methods, solid and mechanics analyses, measurement advances, and a pool of educated graduate students. Progress is reported for 11 areas of study.

  13. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice.

    PubMed

    Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

    2016-01-01

    Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

  14. NASA-UVa light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Stoner, Glenn E.; Swanson, Robert E.; Thornton, Earl A.; Wawner, Franklin E., Jr.

    1991-01-01

    The general objective of the NASA-UVa Light Aerospace Alloy and Structures Technology Program was to conduct research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures. The following research areas were actively investigated: (1) mechanical and environmental degradation mechanisms in advanced light metals and composites; (2) aerospace materials science; (3) mechanics of materials and composites for aerospace structures; and (4) thermal gradient structures.

  15. Effective band structure of random III-V alloys

    NASA Astrophysics Data System (ADS)

    Popescu, Voicu; Zunger, Alex

    2010-03-01

    Random substitutional alloys have no long range order (LRO) or translational symmetry so rigorously speaking they have no E(k) band structure or manifestations thereof. Yet, many experiments on alloys are interpreted using the language of band theory, e.g. inferring Van Hove singularities, band dispersion and effective masses. Many standard alloy theories (VCA- or CPA-based) have the LRO imposed on the alloy Hamiltonian, assuming only on-site disorder, so they can not be used to judge the extent of LRO that really exists. We adopt the opposite way, by using large (thousand atom) randomly generated supercells in which chemically identical alloy atoms are allowed to have different local environments (a polymorphous representation). This then drives site-dependent atomic relaxation as well as potential fluctuations. The eigenstates from such supercells are then mapped onto the Brillouin zone (BZ) of the primitive cell, producing effective band dispersion. Results for (In,Ga)X show band-like behaviour only near the centre and faces of the BZ but rapidly lose such characteristics away from γ or for higher bands. We further analyse the effects of stoichiometry variation, internal relaxation, and short-range order on the alloy band structure.

  16. NASA-UVA light aerospace alloy and structures technology program

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Thornton, Earl A.; Stoner, Glenn E.; Swanson, Robert E.; Wawner, Franklin E., Jr.; Wert, John A.

    1989-01-01

    The report on progress achieved in accomplishing of the NASA-UVA Light Aerospace Alloy and Structures Technology Program is presented. The objective is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys and associated thermal gradient structures in close collaboration with researchers. The efforts will produce basic understanding of material behavior, new monolithic and composite alloys, processing methods, solid and fluid mechanics analyses, measurement advances, and a pool of educated graduate students. The presented accomplishments include: research on corrosion fatigue of Al-Li-Cu alloy 2090; research on the strengthening effect of small In additions to Al-Li-Cu alloys; research on localized corrosion of Al-Li alloys; research on stress corrosion cracking of Al-Li-Cu alloys; research on fiber-matrix reaction studies (Ti-1100 and Ti-15-3 matrices containing SCS-6, SCS-9, and SCS-10 fibers); and research on methods for quantifying non-random particle distribution in materials that has led to generation of a set of computer programs that can detect and characterize clusters in particles.

  17. Electron Beam Freeform Fabrication of Titanium Alloy Gradient Structures

    NASA Technical Reports Server (NTRS)

    Brice, Craig A.; Newman, John A.; Bird, Richard Keith; Shenoy, Ravi N.; Baughman, James M.; Gupta, Vipul K.

    2014-01-01

    Historically, the structural optimization of aerospace components has been done through geometric methods. A monolithic material is chosen based on the best compromise between the competing design limiting criteria. Then the structure is geometrically optimized to give the best overall performance using the single material chosen. Functionally graded materials offer the potential to further improve structural efficiency by allowing the material composition and/or microstructural features to spatially vary within a single structure. Thus, local properties could be tailored to the local design limiting criteria. Additive manufacturing techniques enable the fabrication of such graded materials and structures. This paper presents the results of a graded material study using two titanium alloys processed using electron beam freeform fabrication, an additive manufacturing process. The results show that the two alloys uniformly mix at various ratios and the resultant static tensile properties of the mixed alloys behave according to rule-of-mixtures. Additionally, the crack growth behavior across an abrupt change from one alloy to the other shows no discontinuity and the crack smoothly transitions from one crack growth regime into another.

  18. Methods for making lithium vanadium oxide electrode materials

    DOEpatents

    Schutts, Scott M.; Kinney, Robert J.

    2000-01-01

    A method of making vanadium oxide formulations is presented. In one method of preparing lithium vanadium oxide for use as an electrode material, the method involves: admixing a particulate form of a lithium compound and a particulate form of a vanadium compound; jet milling the particulate admixture of the lithium and vanadium compounds; and heating the jet milled particulate admixture at a temperature below the melting temperature of the admixture to form lithium vanadium oxide.

  19. Effect of the chemical composition and the structural and phases states of materials on hydrogen retention

    NASA Astrophysics Data System (ADS)

    Chernov, I. I.; Stal'tsov, M. S.; Kalin, B. A.; Bogachev, I. A.; Guseva, L. Yu.; Korshunov, S. N.

    2017-07-01

    The results of investigation of the effect of chemical composition and structural and phase states of reactor steels and vanadium alloys on their capture and retention of hydrogen introduced into the materials in various ways are presented. It is shown that, in the case of identical conditions of hydrogen introduction, the amount of hydrogen captured by austenitic steels is substantially higher than that captured by ferritic/ martensitic steels. At the same time, the EP450 ODS ferritic/martensitic steel dispersion-strengthened with nanosized yttrium oxide particles retains a substantially higher amount of hydrogen as compared to that retained in the EP450 matrix steel. The alloying of vanadium with tungsten, zirconium, and titanium leads to an increase in the amount of retained hydrogen. The effect of titanium content on hydrogen retention is found to be nonmonotonic; the phenomenon is explained from a physical view point.

  20. Structural studies of liquid Co–Sn alloys

    PubMed Central

    Yakymovych, A.; Shtablavyi, I.; Mudry, S.

    2014-01-01

    An analysis of the structure features of liquid Co–Sn alloys has been performed by means of X-ray diffraction method, viscosity coefficient analysis and computer simulation method. The X-ray diffraction investigations were carried out over a wide concentration range at the temperature 1473 K. It was found that the structure of these alloys can be described in the frame of independent X-ray scattering model. The viscosity coefficient was calculated by an excess entropy scaling and compared with experimental data. PMID:25328282

  1. Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

    NASA Astrophysics Data System (ADS)

    Natalio, Filipe; André, Rute; Hartog, Aloysius F.; Stoll, Brigitte; Jochum, Klaus Peter; Wever, Ron; Tremel, Wolfgang

    2012-08-01

    Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling. However, these materials can damage the environment through metal leaching (for example, of copper and zinc) and bacteria resistance. Here, we show that vanadium pentoxide nanowires act like naturally occurring vanadium haloperoxidases to prevent marine biofouling. In the presence of bromide ions and hydrogen peroxide, the nanowires catalyse the oxidation of bromide ions to hypobromous acid (HOBr). Singlet molecular oxygen (1O2) is formed and this exerts strong antibacterial activity, which prevents marine biofouling without being toxic to marine biota. Vanadium pentoxide nanowires have the potential to be an alternative approach to conventional anti-biofouling agents.

  2. Effects of as-cast and wrought Cobalt-Chrome-Molybdenum and Titanium-Aluminium-Vanadium alloys on cytokine gene expression and protein secretion in J774A.1 macrophages.

    PubMed

    Jakobsen, Stig S; Larsen, A; Stoltenberg, M; Bruun, J M; Soballe, K

    2007-09-11

    Insertion of metal implants is associated with a possible change in the delicate balance between pro- and anti-inflammatory proteins, probably leading to an unfavourable predominantly pro-inflammatory milieu. The most likely cause is an inappropriate activation of macrophages in close relation to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines (TNF-alpha, IL-6, IL-alpha, IL-1beta, IL-10) and proteins known to induce proliferation (M-CSF), chemotaxis (MCP-1) and osteogenesis (TGF-beta, OPG) were determined by ELISA and Real Time reverse transcriptase - PCR (Real Time rt-PCR). Lactate dehydrogenase (LDH) was measured in the medium to asses the cell viability. Surface properties of the discs were characterised with a profilometer and with energy dispersive X-ray spectroscopy. We here report, for the first time, that the prosthetic material surface (non-phagocytable) of as-cast high carbon CoCrMo reduces the pro-inflammatory cytokine IL-6 transcription, the chemokine MCP-1 secretion, and M-CSF secretion by 77%, 36%, and 62%, respectively. Furthermore, we found that reducing surface roughness did not affect this reduction. The results suggest that as-cast CoCrMo alloy is more inert than wrought CoCrMo and wrought TiAlV alloys and could prove to be a superior implant material generating less inflammation which might result in less osteolysis.

  3. Structure-property relationships in NO x sensor materials composed of arrays of vanadium oxide nanoclusters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.

    The mixed-valent vanadium oxide based three-dimensional framework structure species [Cd 3(H 2O) 12V 16 IVV 2 VO 36(OH) 6(AO 4)]∙24H 2O, (A=V,S) (Cd 3(VO) o) represents a rare example of an interesting sensor material which exhibits NO x {NO+NO 2} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd 3(VO) o decreases in air. Combined characterization studies revealed that the building block, {V 18O 42(AO 4)} cluster, of 3-D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadiummore » which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd 3(VO) o. Based on these results we propose that the changes in semiconducting properties of Cd 3(VO) o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.« less

  4. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

    PubMed Central

    Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

    2016-01-01

    Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal. PMID:26962395

  5. Evolution of Nano-structured Quasicrystals from Amorphous alloys

    NASA Astrophysics Data System (ADS)

    Xing, L. Q.; Kelton, K. F.

    2002-03-01

    Ta shows a significant effect on the precipitation of quasicrystals in (Zr_1-xTa_x)_64Cu_18Ni_8Al_10 amorphous alloys. The amorphous alloy made without Ta forms precipitates of tetragonal Zr_2Cu primary phases upon annealing. The addition of a small amount of Ta ( ~ 3 at%) to the alloy initiates the precipitation of primary icosahedral quasicrystal phases. Moreover, as the Ta concentration increases, the size of the precipitates decreases dramatically. To study the effect of Ta in this alloy system and to understand the mechanism for the precipitation of nano-structured quasicrystals, we have investigated the crystallization characteristics of the alloys made with different Ta concentration using DSC, checked the structures of the annealed samples with TEM and X-ray diffraction, and analyzed the kinetics of the crystallization processes. The kinetic parameter and the measured crystal size distribution will be compared with theoretical predictions from conventional nucleation and growth model and from a new model for nucleation that couples the long-range diffusion flux with the interfacial attachment processes.

  6. Structural phase transition, electronic structure and optical properties of half Heusler alloys LiBeZ (Z = As, Sb)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amudhavalli, A.; Rajeswarapalanichamy, R., E-mail: rajeswarapalanichamy@gmail.com

    2016-05-23

    Ab initio calculations are performed to investigate the structural stability, electronic structure, mechanical properties and optical properties of half Heusler alloys (LiBeAs and LiBeSb) for three different phases of zinc blende crystal structure. Among the considered phases, α- phase is found to be the most stable phase for these alloys at normal pressure. A pressure induced structural phase transition from α-phase to β- phase is observed for LiBeAs. The electronic structure reveals that these alloys are semiconductors. The optical properties confirm that these alloys are semiconductor in nature.

  7. One-step hydrothermal synthesis of hexangular starfruit-like vanadium oxide for high power aqueous supercapacitors

    NASA Astrophysics Data System (ADS)

    Shao, Jie; Li, Xinyong; Qu, Qunting; Zheng, Honghe

    2012-12-01

    Homogenous hexangular starfruit-like vanadium oxide was prepared for the first time by a one-step hydrothermal method. The assembly process of hexangular starfruit-like structure was observed from TEM images. The electrochemical performance of starfruit-like vanadium oxide was examined by cyclic voltammetry and galvanostatic charge/discharge. The obtained starfruit-like vanadium oxide exhibits a high power capability (19 Wh kg-1 at the specific power of 3.4 kW kg-1) and good cycling stability for supercapacitors application.

  8. The solubility of metals in Pb17Li liquid alloy

    NASA Astrophysics Data System (ADS)

    Borgstedt, H. U.; Feuerstein, H.

    1992-09-01

    The solubility data of iron in the eutectic alloy Pb17Li which were evaluated from corrosion tests in a turbulent flow of the molten alloy are discussed in the frame of solubilities of the transition metals in liquid lead. It is shown that the solubility of iron in the alloy is close to that in lead. This is also the fact for several other alloying elements of steels.A comparison of all known data shows that they are in agreement with generally shown trends for the solubility of the transition metals in low melting metals. These trends indicate comparably high solubilities of nickel and manganese in the liquid metals, lower saturation concentrations of vanadium, chromium, iron, and cobalt, and extremely low solubility of molybdenum.

  9. Vanadium in landscape components of western Transbaikalia

    NASA Astrophysics Data System (ADS)

    Kashin, V. K.

    2017-10-01

    Vanadium in soil-forming rocks, soils, and vegetation of forest-steppe, steppe, and dry-steppe landscapes of Transbaikalia has been studied. The mean element contents in rocks and soils are equal to its mean natural abundances (clarke values). The content of vanadium in soils is strictly determined by its content in parent materials; its dependence on the vanadium concentration in plants and on the soil pH and humus is less pronounced. With respect to the coefficient of biological uptake by plants, vanadium is assigned to the group of elements of slight accumulation (0.10-0.33) on mineral soils and of moderate accumulation (1.1-1.5) on peat bog soils. The mean vanadium concentration in steppe, meadow, and cultivated vegetation exceeds the norm for animals by 1.7-2.6 times but does not rich toxic levels. Vanadium uptake by plants is most intensive in meadow cenoses and is less intensive in dry-steppe cenoses.

  10. The role of vanadium in biology.

    PubMed

    Rehder, Dieter

    2015-05-01

    Vanadium is special in at least two respects: on the one hand, the tetrahedral anion vanadate(v) is similar to the phosphate anion; vanadate can thus interact with various physiological substrates that are otherwise functionalized by phosphate. On the other hand, the transition metal vanadium can easily expand its sphere beyond tetrahedral coordination, and switch between the oxidation states +v, +iv and +iii in a physiological environment. The similarity between vanadate and phosphate may account for the antidiabetic potential of vanadium compounds with carrier ligands such as maltolate and picolinate, and also for vanadium's mediation in cardiovascular and neuronal defects. Other potential medicinal applications of more complex vanadium coordination compounds, for example in the treatment of parasitic tropical diseases, may also be rooted in the specific properties of the ligand sphere. The ease of the change in the oxidation state of vanadium is employed by prokarya (bacteria and cyanobacteria) as well as by eukarya (algae and fungi) in respiratory and enzymatic functions. Macroalgae (seaweeds), fungi, lichens and Streptomyces bacteria have available haloperoxidases, and hence enzymes that enable the 2-electron oxidation of halide X(-) with peroxide, catalyzed by a Lewis-acidic V(V) center. The X(+) species thus formed can be employed to oxidatively halogenate organic substrates, a fact with implications also for the chemical processes in the atmosphere. Vanadium-dependent nitrogenases in bacteria (Azotobacter) and cyanobacteria (Anabaena) convert N2 + H(+) to NH4(+) + H2, but are also receptive for alternative substrates such as CO and C2H2. Among the enigmas to be solved with respect to the utilization of vanadium in nature is the accumulation of V(III) by some sea squirts and fan worms, as well as the purport of the nonoxido V(IV) compound amavadin in the fly agaric.

  11. Microwave assisted growth of nanorods vanadium dioxide VO2 (R): structural and electrical properties

    NASA Astrophysics Data System (ADS)

    Derkaoui, I.; Khenfouch, M.; Mothudi, B. M.; Moloi, S. J.; Zorkani, I.; Jorio, A.; Maaza, M.

    2018-03-01

    Nanostructured metal oxides have attracted a lot of attention recently owning to their unique structural advantages and demonstrated promising chemical and physical properties for various applications. In this study, we report the structural and electrical properties of vanadium dioxide VO2 (R) prepared via a single reaction microwave (SRC) synthesis. Our results are revealing that the components of VO2 (R) films have a rod-like shape with a uniform size distribution. The nanorods with very smooth and flat surfaces have a typical length of up to 2μm and a width of about several nanometers. The structural investigations reveal the high crystallinity of VO2 (R) ensuring good electrical contact and showing a high conductivity as a function of temperature. This synthesis method provides a new simple route to fabricate one-dimensional nanostructured metal oxides which is suitable for a large field of applications especially for smart windows.

  12. Rare-earth metals in nickel aluminide-based alloys: III. Structure and properties of multicomponent Ni3Al-based alloys

    NASA Astrophysics Data System (ADS)

    Bazyleva, O. A.; Povarova, K. B.; Kazanskaya, N. K.; Drozdov, A. A.

    2009-04-01

    The possibility of increasing the life of heterophase cast light Ni3Al-based superalloys at temperatures higher than 0.8 T m of Ni3Al is studied when their directional structure is additionally stabilized by nanoprecipitates, which form upon additional alloying of these alloys by refractory and active metals, and using special methods for preparing and melting of an alloy charge. The effect of the method of introducing the main components and refractory reaction-active and surface-active alloying elements into Ni3Al-based cast superalloys, which are thermally stable natural composite materials of the eutectic type, on the structure-phase state and the life of these alloys is studied. When these alloys are melted, it is necessary to perform a set of measures to form particles of refractory oxide cores covered with the β-NiAl phase and, then, γ'prim-Ni3Al phase precipitates during solidification. The latter phase forms the outer shell of grain nuclei, which provides high thermal stability and hot strength of an intermetallic compound-based alloy. As a result, a modified structure that is stabilized by the nanoprecipitates of nickel and aluminum lanthanides and the nanoprecipitates of phases containing refractory metals is formed. This structure enhances the life of the alloy at 1000 °C by a factor of 1.8-2.5.

  13. The role of phosphate additive in stabilization of sulphuric-acid-based vanadium(V) electrolyte for all-vanadium redox-flow batteries

    NASA Astrophysics Data System (ADS)

    Roznyatovskaya, Nataliya V.; Roznyatovsky, Vitaly A.; Höhne, Carl-Christoph; Fühl, Matthias; Gerber, Tobias; Küttinger, Michael; Noack, Jens; Fischer, Peter; Pinkwart, Karsten; Tübke, Jens

    2017-09-01

    Catholyte in all-vanadium redox-flow battery (VRFB) which consists of vanadium salts dissolved in sulphuric acid is known to be stabilized by phosphoric acid to slow down the thermal aging at temperatures higher than 40 °C. To reveal the role of phosphoric acid, the thermally-induced aggregation is investigated using variable-temperature 51V, 31P, 17O, 1H nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). The results indicate that the thermal stabilization of vanadium(V) electrolyte is attained by the involvement of monomeric and dimeric vanadium(V) species in the reaction with phosphoric acid which is concurrent to the formation of neutral hydroxo-aqua vanadium(V) precipitation precursor. The dimers are stabilized by counter ions due to association reaction or if such stabilization is not possible, precipitation of vanadium pentoxide is favored. The evolution of particles size distributions at 50 °C in electrolyte samples containing 1.6 M vanadium and 4.0 M total sulphate and the pathways of precipitate formation are discussed. The optimal total phosphate concentration is found to be of 0.15 M. However, the induction time is assumed to be dependent not only on the total phosphate concentrations, but also on the ratio of total vanadium(V) to sulphate concentrations.

  14. Investigation of Silica-Supported Vanadium Oxide Catalysts by High-Field 51 V Magic-Angle Spinning NMR

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jaegers, Nicholas R.; Wan, Chuan; Hu, Mary Y.

    Supported V2O5/SiO2 catalysts were studied using solid state 51V MAS NMR at a sample spinning rate of 36 kHz and at a magnetic field of 19.975 T for a better understanding of the coordination of the vanadium oxide as a function of environmental conditions . Structural transformations of the supported vanadium oxide species between the catalyst in the dehydrated state and hydrated state under an ambient environment were revisited to examine the degree of oligomerization and the effect of water. The experimental results indicate the existence of a single dehydrated surface vanadium oxide species that resonates at -675 ppm andmore » two vanadium oxide species under ambient conditions that resonate at -566 and -610 ppm, respectively. No detectable structural difference was found as a function of vanadium oxide loading on SiO2 (3% V2O5/SiO2 and 8% V2O5/SiO2). Quantum chemistry simulations of the 51V NMR chemical shifts on predicted surface structures were used as an aide in understanding potential surface vanadium oxide species on the silica support. The results suggest the formation of isolated surface VO4 units for the dehydrated catalysts with the possibility of dimer and cyclic trimer presence. The absence of bridging V-O-V vibrations (~200-300 cm-1) in the Raman spectra [Gao et al. J. Phys. Chem. B 1998, 102, 10842-10852], however, indicates that the isolated surface VO4 sites are the dominant dehydrated surface vanadia species on silica. Upon exposure to water, hydrolysis of the bridging V-O-Si bonds is most likely responsible for the decreased electron shielding experienced by vanadium. No indicators for the presence of hydrated decavanadate clusters or hydrated vanadia gels previously proposed in the literature were detected in this study.« less

  15. Process for making a martensitic steel alloy fuel cladding product

    DOEpatents

    Johnson, Gerald D.; Lobsinger, Ralph J.; Hamilton, Margaret L.; Gelles, David S.

    1990-01-01

    This is a very narrowly defined martensitic steel alloy fuel cladding material for liquid metal cooled reactors, and a process for making such a martensitic steel alloy material. The alloy contains about 10.6 wt. % chromium, about 1.5 wt. % molybdenum, about 0.85 wt. % manganese, about 0.2 wt. % niobium, about 0.37 wt. % silicon, about 0.2 wt. % carbon, about 0.2 wt. % vanadium, 0.05 maximum wt. % nickel, about 0.015 wt. % nitrogen, about 0.015 wt. % sulfur, about 0.05 wt. % copper, about 0.007 wt. % boron, about 0.007 wt. % phosphorous, and with the remainder being essentially iron. The process utilizes preparing such an alloy and homogenizing said alloy at about 1000.degree. C. for 16 hours; annealing said homogenized alloy at 1150.degree. C. for 15 minutes; and tempering said annealed alloy at 700.degree. C. for 2 hours. The material exhibits good high temperature strength (especially long stress rupture life) at elevated temperature (500.degree.-760.degree. C.).

  16. Dual-phase Cr-Ta alloys for structural applications

    DOEpatents

    Liu, Chain T.; Brady, Michael P.; Zhu, Jiahong; Tortorelli, Peter F.

    2001-01-01

    Dual phase alloys of chromium containing 2 to 11 atomic percent tantalum with minor amounts of Mo, Cr, Ti, Y, La, Cr, Si and Ge are disclosed. These alloys contain two phases including Laves phase and Cr-rich solid solution in either eutectic structures or dispersed Laves phase particles in the Cr-rich solid solution matrix. The alloys have superior mechanical properties at high temperature and good oxidation resistance when heated to above 1000.degree. C. in air.

  17. Atomic scale modelling of hexagonal structured metallic fission product alloys

    PubMed Central

    Middleburgh, S. C.; King, D. M.; Lumpkin, G. R.

    2015-01-01

    Noble metal particles in the Mo-Pd-Rh-Ru-Tc system have been simulated on the atomic scale using density functional theory techniques for the first time. The composition and behaviour of the epsilon phases are consistent with high-entropy alloys (or multi-principal component alloys)—making the epsilon phase the only hexagonally close packed high-entropy alloy currently described. Configurational entropy effects were considered to predict the stability of the alloys with increasing temperatures. The variation of Mo content was modelled to understand the change in alloy structure and behaviour with fuel burnup (Mo molar content decreases in these alloys as burnup increases). The predicted structures compare extremely well with experimentally ascertained values. Vacancy formation energies and the behaviour of extrinsic defects (including iodine and xenon) in the epsilon phase were also investigated to further understand the impact that the metallic precipitates have on fuel performance. PMID:26064629

  18. Synthesis and Structure of Vanadium Halide Complexes Containing Diphosphine Ligands with Pendant Amines

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Egbert, Jonathan D.; Labios, Liezel A.; Darmon, Jonathan M.

    2016-02-18

    A series of vanadium(III) diiodide complexes of the formula CpV(P RN R'P R)I 2 (Cp = 5-C 5H 5; P RN R'P R = (R 2PCH 2) 2N(R)), where R = Et, R = Me (1a), R = Ph (1b); R = Ph, R = Me (1c)) is reported. The corresponding vanadium(II) monoiodide complexes of the formula CpV(P RN R' PR)I, where R = Et, R = Me (2a), R = Ph (2b); R = Ph, R = Me (2c)) were prepared in THF by reduction of 1a-c with Zn powder. The paramagnetic complexes 1a-c and 2a-c are characterized bymore » elemental analysis, 1H NMR spectroscopy, and by cyclic voltammetry for complexes 2b and 4b. Complexes 1c and 2a-c were also characterized in the single crystal by X-ray crystallography. We report the preparation of the vanadium(II) complexes CpV(P Ph 2N Ph 2)I (3) (P Ph 2N Ph 2 = 1,5-diphenyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) and trans-[VCl 2(PEtNMePEt)2] (4a) and trans-[VCl 2(PEtNPhPEt) 2] (4b). These complexes represent initial coordination chemistry of vanadium complexes with P RN R'P R and P Ph 2N Ph 2 diphosphine ligands, which contain a pendant amine in the second coordination sphere. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.« less

  19. A combined theoretical-experimental study of interactions between vanadium ions and Nafion membrane in all-vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Intan, Nadia N.; Klyukin, Konstantin; Zimudzi, Tawanda J.; Hickner, Michael A.; Alexandrov, Vitaly

    2018-01-01

    Vanadium redox flow batteries (VRFBs) are a promising solution for large-scale energy storage, but a number of problems still impede the deployment of long-lifetime VRFBs. One important aspect of efficient operation of VRFBs is understanding interactions between vanadium species and the membrane. Herein, we investigate the interactions between all four vanadium cations and Nafion membrane by a combination of infrared (IR) spectroscopy and density-functional-theory (DFT)-based static and molecular dynamics simulations. It is observed that vanadium species primarily lead to changes in the IR spectrum of Nafion in the SO3- spectral region which is attributed to the interaction between vanadium species and the SO3- exchange sites. DFT calculations of vanadium -Nafion complexes in the gas phase show that it is thermodynamically favorable for all vanadium cations to bind to SO3- via a contact pair mechanism. Car-Parrinello molecular dynamics-based metadynamics simulations of cation-Nafion systems in aqueous solution suggest that V2+ and V3+ species coordinate spontaneously to SO3-, which is not the case for VO2+ and VO2+ . The interaction behavior of the uncycled membrane determined in this study is used to explain the experimentally observed changes in the vibrational spectra, and is discussed in light of previous results on device-cycled membranes.

  20. Temperature-dependent mechanical behavior of silicon dioxide, gold and gold-vanadium thin films for VLSI integrated circuits and MicroElectroMechanical systems (MEMs)

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Tzer

    The Semiconductor Industry has grown rapidly in the last twenty years. The national technology roadmap for semiconductors plans for developing the complexity and packing density of semiconductor devices into the next decade, allowing ever smaller and more densely packed structures to be fabricated. Recently, MEMS (Micro-Electro-Mechanical Systems) have become important in modern technology. The goal of MEMs is to integrate many types of miniature devices on a single chip, creating a new micro-world. The oxidation of silicon is one of the most important processes in semiconductor technology. Producing high-quality IC's and MEMS devices requires an understanding of the basic oxidation mechanism. In addition, for the reliability of IC's and MEMS devices, the mechanical properties of the oxide play a critical role. There has been an apparent convergence of opinion on the relevant mechanism leading to the "standard computational model" for stress effects on silicon oxidation. This model has recently become suspect. Most of the reasonably direct experimental data on the flow properties of SiO 2 thin film do not support a stress-dependent viscosity of the sort envisioned by the model. Gold and gold vanadium alloys are used in electrical interconnections and in radio frequency switch contacts for the semiconductor industry, MEMs sensors for the aerospace industry and also in brain probes by the bioelectronics mechanical industry. Despite the strong potential usage of gold and gold vanadium thin films at the small scale, very little is known about their mechanical properties. Our goal was to experimentally investigate stress and its influence on SiO2 thin films and the mechanical properties of gold and gold vanadium thin films at room temperature and at elevated temperature of different vanadium concentration. We found that the application of relatively small amounts of bending to an oxidizing silicon substrate leads to significant decreases in oxide thickness in the

  1. Effects of vanadium and processing parameters on the structures and properties of a direct-quenched low-carbon Mo-B steel

    NASA Astrophysics Data System (ADS)

    Taylor, K. A.; Hansen, S. S.

    1991-10-01

    The structures and mechanical properties of a series of thermomechanically processed, direct-quenched martensitic 0.1C-1.4Mn-0.5Mo-B steels containing from 0 to 0.24 wt pct va have been investigated and compared to those obtained after a conventional austenitizing-and-quenching treatment. For all processing conditions, vanadium additions to the base composition are found to increase hardenability (ideal critical parameter, D,); the largest effects (up to a 90 pct increase in D I) are noted when samples are hot-rolled prior to direct quenching. Vanadium additions are also observed to provide significant strengthening in the quenched-and-tempered condition as the result of the precipitation of fine V-Mo carbides. The strengthening increment due to these precipitates is approximately 100 MPa/0.1 wt pct V over the range of vanadium additions examined. At the same time, however, these precipitates reduce notch toughness; on the average, the 20 J transition temperature increases by about 4 °C for each 10 MPa increment in yield strength. For the conditions examined, the best balance of strength and toughness is obtained in direct-quenched samples which are control-rolled (i.e., rolling is completed below the austenite recrystallization temperature) prior to quenching.

  2. Effective Recovery of Vanadium from Oil Refinery Waste into Vanadium-Based Metal-Organic Frameworks.

    PubMed

    Zhan, Guowu; Ng, Wei Cheng; Lin, Wenlin Yvonne; Koh, Shin Nuo; Wang, Chi-Hwa

    2018-03-06

    Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal-organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (>98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length: > 10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source.

  3. Effect of substrate temperature on thermochromic vanadium dioxide thin films sputtered from vanadium target

    NASA Astrophysics Data System (ADS)

    Madiba, I. G.; Kotsedi, L.; Ngom, B. D.; Khanyile, B. S.; Maaza, M.

    2018-05-01

    Vanadium dioxide films have been known as the most promising thermochromic thin films for smart windows which self-control the solar radiation and heat transfer for energy saving, comfort in houses and automotives. Such an attractive technological application is due to the fact that vanadium dioxide crystals exhibit a fast semiconductor-to-metal phase transition at a transition temperature Tc of about 68 °C, together with sharp optical changes from high transmitive to high reflective coatings in the IR spectral region. The phase transition has been associated with the nature of the microstructure, stoichiometry and stresses related to the oxide. This study reports on the effect of the crystallographic quality controlled by the substrate temperature on the thermochromic properties of vanadium dioxide thin films synthesized by reactive radio frequency inverted cylindrical magnetron sputtering from vanadium target. The reports results are based on X-ray diffraction, Atomic force microscopy, and UV-Visible spectrophotometer. The average crystalline grain size of VO2 increases with the substrate temperature, inducing stress related phenomena within the films.

  4. Microbial vanadium (V) reduction in groundwater with different soils from vanadium ore mining areas.

    PubMed

    Hao, Liting; Zhang, Baogang; Feng, Chuanping; Zhang, Zhenya; Lei, Zhongfang; Shimizu, Kazuya; Cao, Xuelong; Liu, Hui; Liu, Huipeng

    2018-07-01

    This work investigated the potential of vanadium (V) (V(V)) bioreduction by using soils sampled from four main kinds of vanadium ore mining areas, i.e. vanadium titanomagnetite, stone coal, petroleum associated minerals and uvanite as inocula. During a typical operation cycle of 60 h, the soils from vanadium titanomagnetite area and petroleum associated minerals area exhibited higher V(V) removal efficiencies, about 92.0 ± 2.0% and 91.0 ± 1.9% in comparison to 87.1 ± 1.9% and 69.0 ± 1.1% for the soils from uvanite and stone coal areas, respectively. Results from high-throughput 16 S rRNA gene pyrosequencing analysis reflect the accumulation of Bryobacter and Acidobacteriaceae with capabilities of V(V) reduction, accompanied with other functional species. This study is helpful to search new functional species for V(V) reduction and to develop in situ bioremediations of V(V) polluted groundwater. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Characterization of rodlike structures in Si-Ge-GaP alloys

    NASA Astrophysics Data System (ADS)

    Srikant, V.; Jesser, W. A.; Rosi, F. D.

    1996-07-01

    High-temperature microstructure of Si-Ge alloys containing 10-15 mole % GaP were studied. Quenching the 80/20 Si-Ge alloy (80 at. % Si) from above 1125 °C and the 50/50 Si-Ge alloy (50 at. % Si) from above 1025 °C resulted in a duplex microstructure. The two-phase regions consisted of a regular array of rodlike structures (GaP) in a Si-Ge matrix whereas the monophase regions were pure Si-Ge. These rodlike structures were found to lie along the [001] direction and result in {002} spots in a [100] electron diffraction pattern. The ``rods'' were about 35 and 45 nm in diameter in the case of the 80/20 and 50/50 alloy, respectively. These structures are not stable on annealing and do not form when the solidification rate is decreased.

  6. Synthesis, Characterization, Antioxidant Status, and Toxicity Study of Vanadium-Rutin Complex in Balb/c Mice.

    PubMed

    Roy, Souvik; Majumdar, Sumana; Singh, Amit Kumar; Ghosh, Balaram; Ghosh, Nilanjan; Manna, Subhadip; Chakraborty, Tania; Mallick, Sougato

    2015-08-01

    A new trend was developed for the formation of a complex between vanadium and flavonoid derivatives in order to increase the intestinal absorption and to reduce the toxicity of vanadium compounds. The vanadium-rutin complex was characterized by several spectroscopic techniques like ultraviolet (UV)-visible, Fourier transform infrared (FTIR), NMR, mass spectrometry, and microscopic evaluation by scanning electron microscopy. The mononuclear complex was formed by the interaction between vanadium and rutin with 1:2 metal to ligand stoichiometry. Antioxidant activity of the complex was evaluated by 1,1-diphenyl-2 picrylhydrazyl, ferric-reducing power, and 2,2'-azin-obis 3-ethylbenzothiazoline-6-sulphonic acid methods. It was shown that radical scavenging activity and ferric-reducing potential of free rutin was lower as compared with vanadium-rutin complex. The study was also investigated for oral acute toxicity and 28 days repeated oral subacute toxicity study of vanadium-rutin complex in balb/c mice. The vanadium-rutin complex showed mortality at a dose of 120 mg/kg in the balb/c mice. In 28 days repeated oral toxicity study, vanadium-rutin complex was administered to both sex of balb/c mice at dose levels of 90, 45, and 20 ppm, respectively. In addition, subacute toxicity study of vanadium-rutin complex (at 90 ppm dose level) showed increase levels of white blood cell (WBC), total bilirubin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), creatinine, and blood urea nitrogen and decrease level of total protein (TP) as compared with control group. Histopathological study of vanadium-rutin showed structural alteration in the liver, kidney, and stomach at 90 ppm dose level. No observed toxic level of vanadium-rutin complex at 20 ppm dose level could be good for further study.

  7. Orientation of Vanadium Dioxide Grains on Various Substrates

    NASA Astrophysics Data System (ADS)

    Rivera, Felipe; Davis, Robert; Vanfleet, Richard

    2010-10-01

    Crystalline vanadium dioxide VO2 experiences a fast and reversible semiconductor-to-metal structural phase transition near 68^oC. The changes exhibited during this phase transition comprise a well known change in resistivity of several orders of magnitude, as well as a significant drop in optical transmittance in the infrared. Due to the changes in these optical and electronic properties, vanadium dioxide shows promise as a material to be used in many applications ranging from thermochromic window coatings to optoelectronic devices. However, since there is a structural component to the phase transition of VO2, it is of interest to study the orientation of the crystalline grains deposited. Substrates such as glass, SiO2, Sapphire, and TiO2 have been used for the deposition of this material. We used orientation imaging microscopy to study and characterize the orientation of the grains deposited on several of these substrates. Here we present results on this study.

  8. Method of preparing copper-dendritic composite alloys for mechanical reduction

    DOEpatents

    Verhoeven, John D.; Gibson, Edwin D.; Schmidt, Frederick A.; Spitzig, William A.

    1988-01-01

    Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2000 .mu.m, and the platelets thicknesses of 100 to 2000 .mu.m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt.

  9. Effect of Different Structural Materials on Neutronic Performance of a Hybrid Reactor

    NASA Astrophysics Data System (ADS)

    Übeyli, Mustafa; Tel, Eyyüp

    2003-06-01

    Selection of structural material for a fusion-fission (hybrid) reactor is very important by taking into account of neutronic performance of the blanket. Refractory metals and alloys have much higher operating temperatures and neutron wall load (NWL) capabilities than low activation materials (ferritic/martensitic steels, vanadium alloys and SiC/SiC composites) and austenitic stainless steels. In this study, effect of primary candidate refractory alloys, namely, W-5Re, T111, TZM and Nb-1Zr on neutronic performance of the hybrid reactor was investigated. Neutron transport calculations were conducted with the help of SCALE 4.3 System by solving the Boltzmann transport equation with code XSDRNPM. Among the investigated structural materials, tantalum had the worst performance due to the fact that it has higher neutron absorption cross section than others. And W-5Re and TZM having similar results showed the best performance.

  10. Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

    NASA Astrophysics Data System (ADS)

    Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

    2018-05-01

    Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

  11. Linking Precursor Alterations to Nanoscale Structure and Optical Transparency in Polymer Assisted Fast-Rate Dip-Coating of Vanadium Oxide Thin Films

    PubMed Central

    Glynn, Colm; Creedon, Donal; Geaney, Hugh; Armstrong, Eileen; Collins, Timothy; Morris, Michael A.; Dwyer, Colm O’

    2015-01-01

    Solution processed metal oxide thin films are important for modern optoelectronic devices ranging from thin film transistors to photovoltaics and for functional optical coatings. Solution processed techniques such as dip-coating, allow thin films to be rapidly deposited over a large range of surfaces including curved, flexible or plastic substrates without extensive processing of comparative vapour or physical deposition methods. To increase the effectiveness and versatility of dip-coated thin films, alterations to commonly used precursors can be made that facilitate controlled thin film deposition. The effects of polymer assisted deposition and changes in solvent-alkoxide dilution on the morphology, structure, optoelectronic properties and crystallinity of vanadium pentoxide thin films was studied using a dip-coating method using a substrate withdrawal speed within the fast-rate draining regime. The formation of sub-100 nm thin films could be achieved rapidly from dilute alkoxide based precursor solutions with high optical transmission in the visible, linked to the phase and film structure. The effects of the polymer addition was shown to change the crystallized vanadium pentoxide thin films from a granular surface structure to a polycrystalline structure composed of a high density of smaller in-plane grains, resulting in a uniform surface morphology with lower thickness and roughness. PMID:26123117

  12. Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Bo; Chen, Zhaohui; Lu, Gang

    Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings canmore » shed light on other transition metal nitride-based electrochemical energy storage systems.« less

  13. Hyperfine structure measurements of neutral vanadium by laser-induced fluorescence spectroscopy in the wavelength range from 750 nm to 860 nm

    NASA Astrophysics Data System (ADS)

    Başar, Gü.; Güzelçimen, F.; Öztürk, I. K.; Er, A.; Bingöl, D.; Kröger, S.; Başar, Gö.

    2017-11-01

    The hyperfine structure of 57 spectral lines of neutral vanadium has been investigated using a hollow cathode lamp by laser-induced fluorescence spectroscopy in the wavelength range from 750 nm to 860 nm. New magnetic dipole hyperfine structure constants A have been determined for 14 atomic energy levels and new electric quadrupole hyperfine structure constants B for two levels. Additionally previously published hyperfine structure constants A of 56 levels have been measured again. In five cases, the old A values have been rejected and replaced by improved values.

  14. Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

    PubMed

    Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

    2014-12-26

    Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

  15. Mesoporous coaxial titanium nitride-vanadium nitride fibers of core-shell structures for high-performance supercapacitors.

    PubMed

    Zhou, Xinhong; Shang, Chaoqun; Gu, Lin; Dong, Shanmu; Chen, Xiao; Han, Pengxian; Li, Lanfeng; Yao, Jianhua; Liu, Zhihong; Xu, Hongxia; Zhu, Yuwei; Cui, Guanglei

    2011-08-01

    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.

  16. Crystal Structural Effect of AuCu Alloy Nanoparticles on Catalytic CO Oxidation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhan, Wangcheng; Wang, Jinglin; Wang, Haifeng

    2017-06-07

    Controlling the physical and chemical properties of alloy nanoparticles (NPs) is an important approach to optimize NP catalysis. Unlike other tuning knobs, such as size, shape, and composition, crystal structure has received limited attention and not been well understood for its role in catalysis. This deficiency is mainly due to the difficulty in synthesis and fine-tuning of the NPs’ crystal structure. Here, Exemplifying by AuCu alloy NPs with face centered cubic (fcc) and face centered tetragonal (fct) structure, we demonstrate a remarkable difference in phase segregation and catalytic performance depending on the crystal structure. During the thermal treatment in air,more » the Cu component in fcc-AuCu alloy NPs segregates more easily onto the alloy surface as compared to that in fct-AuCu alloy NPs. As a result, after annealing at 250 °C in air for 1 h, the fcc- and fct-AuCu alloy NPs are phase transferred into Au/CuO and AuCu/CuO core/shell structures, respectively. More importantly, this variation in heterostructures introduces a significant difference in CO adsorption on two catalysts, leading to a largely enhanced catalytic activity of AuCu/CuO NP catalyst for CO oxidation. Furthermore, the same concept can be extended to other alloy NPs, making it possible to fine-tune NP catalysis for many different chemical reactions.« less

  17. Extended x-ray absorption fine structure measurements of quasi-isentropically compressed vanadium targets on the OMEGA laser

    NASA Astrophysics Data System (ADS)

    Yaakobi, B.; Boehly, T. R.; Sangster, T. C.; Meyerhofer, D. D.; Remington, B. A.; Allen, P. G.; Pollaine, S. M.; Lorenzana, H. E.; Lorenz, K. T.; Hawreliak, J. A.

    2008-06-01

    The use of in situ extended x-ray absorption fine structure (EXAFS) for characterizing nanosecond laser-shocked vanadium, titanium, and iron has recently been demonstrated. These measurements are extended to laser-driven, quasi-isentropic compression experiments (ICE). The radiation source (backlighter) for EXAFS in all of these experiments is obtained by imploding a spherical target on the OMEGA laser [T. R. Boehly et al., Rev. Sci. Instrum. 66, 508 (1995)]. Isentropic compression (where the entropy is kept constant) enables to reach high compressions at relatively low temperatures. The absorption spectra are used to determine the temperature and compression in a vanadium sample quasi-isentropically compressed to pressures of up to ˜0.75Mbar. The ability to measure the temperature and compression directly is unique to EXAFS. The drive pressure is calibrated by substituting aluminum for the vanadium and interferometrically measuring the velocity of the back target surface by the velocity interferometer system for any reflector (VISAR). The experimental results obtained by EXAFS and VISAR agree with each other and with the simulations of a hydrodynamic code. The role of a shield to protect the sample from impact heating is studied. It is shown that the shield produces an initial weak shock that is followed by a quasi-isentropic compression at a relatively low temperature. The role of radiation heating from the imploding target as well as from the laser-absorption region is studied. The results show that in laser-driven ICE, as compared with laser-driven shocks, comparable compressions can be achieved at lower temperatures. The EXAFS results show important details not seen in the VISAR results.

  18. Evolution of the Structure and Phase Composition of Deformable Refractory Nickel Alloys for GTE Discs Upon Complication of Their Alloying

    NASA Astrophysics Data System (ADS)

    Chabina, E. B.; Filonova, E. V.; Lomberg, B. S.; Morozova, G. I.

    2015-07-01

    Variation of the phase composition and structure of deformable refractory nickel alloys upon complication of their alloying is considered starting with the ÉI437B pioneer domestic alloy with heterophase hardening and ending with alloy VZh175 used as a material for advanced aircraft engines.

  19. Enrichment, Distribution of Vanadium-Containing Protein in Vanadium-Enriched Sea Cucumber Apostichopus japonicus and the Ameliorative Effect on Insulin Resistance.

    PubMed

    Liu, Yanjun; Zhou, Qingxin; Zhao, Yanlei; Wang, Yiming; Wang, Yuming; Wang, Jingfeng; Xu, Jie; Xue, Changhu

    2016-05-01

    Sea cucumbers are a potential source of natural organic vanadium that may improve insulin resistance. In this work, vanadium was accumulated rapidly in blood, body wall, and intestine by sea cucumber Apostichopus japonicus. Furthermore, water-soluble vanadium-containing proteins, the main form of the organic vanadium, were tentatively accumulated and isolated by a bioaccumulation experiment. It was also designed to evaluate the beneficial effect of vanadium-containing proteins (VCPs) from sea cucumber rich in vanadium on the development of hyperglycemia and insulin resistance in C57BL/6J mice fed with a high-fat high-sucrose diet (HFSD). HFSD mice treated with VCPs significantly decreased fasting blood glucose, serum insulin, and HOMA-IR values as compared to HFSD mice, respectively. Serum adiponectin, resistin, TNF-α, and leptin levels in insulin-resistant mice were dramatically reduced by a VCP supplement. These results show an ameliorative effect on insulin resistance by treatment with VCPs. Such compound seems to be a valuable therapy to achieve and/or maintain glycemic control and therapeutic agents in the treatment arsenal for insulin resistance and type 2 diabetes.

  20. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, Philip J.; Braski, David N.; Rowcliffe, Arthur F.

    1989-01-01

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01% to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties.

  1. High thermoelectric figure of merit by resonant dopant in half-Heusler alloys

    NASA Astrophysics Data System (ADS)

    Chen, Long; Liu, Yamei; He, Jian; Tritt, Terry M.; Poon, S. Joseph

    2017-06-01

    Half-Heusler alloys have been one of the benchmark high temperature thermoelectric materials owing to their thermal stability and promising figure of merit ZT. Simonson et al. early showed that small amounts of vanadium doped in Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change with the increased density of states near the Fermi level. We herein report a systematic study on the role of vanadium (V), niobium (Nb), and tantalum (Ta) as prospective resonant dopants in enhancing the ZT of n-type half-Heusler alloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase the Seebeck coefficient in the temperature range 300-1000 K, consistent with a resonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as evident by the systematic decrease in electrical resistivity and Seebeck coefficient. The combination of enhanced Seebeck coefficient due to the presence of V resonant states and the reduced thermal conductivity has led to a state-of-the-art ZT of 1.3 near 850 K in n-type (Hf0.6Zr0.4)0.99V0.01NiSn0.995Sb0.005 alloys.

  2. Assessment of Dephosphorization During Vanadium Extraction Process in Converter

    NASA Astrophysics Data System (ADS)

    Chen, Lian; Diao, Jiang; Wang, Guang; Xie, Bing

    2018-06-01

    Dephosphorization during the vanadium extraction process in the converter was studied. The effects of the slag basicity and FeO content on the dephosphorization and the mineral phases in the phosphorus-containing vanadium slag are discussed. The results show that removal of phosphorus from the hot metal during the vanadium extraction process can be achieved by adding lime into the vanadium extraction converter. The highest dephosphorization rate was obtained at slag basicity of 1.93. The phosphorus distribution ratio increased with increasing FeO content up to 16-18% but decreased thereafter. Vanadium was present in the slag only as spinels rather than calcium vanadate. Phosphorus was still present in the form of calcium phosphate eutectic in calcium silicate. The present work proves that the vanadium extraction and dephosphorization processes are nonconflicting reactions.

  3. Vanadium hydride deuterium-tritium generator

    DOEpatents

    Christensen, Leslie D.

    1982-01-01

    A pressure controlled vanadium hydride gas generator to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

  4. Minimum activation martensitic alloys for surface disposal after exposure to neutron flux

    DOEpatents

    Lechtenberg, Thomas

    1985-01-01

    Steel alloys for long-term exposure to neutron flux have a martensitic microstructure and contain chromium, carbon, tungsten, vanadium and preferably titanium. Activation of the steel is held to within acceptable limits for eventual surface disposal by stringently controlling the impurity levels of Ni, Mo, Cu, N, Co, Nb, Al and Mn.

  5. Hydrogen-induced morphotropic phase transformation of single-crystalline vanadium dioxide nanobeams.

    PubMed

    Hong, Woong-Ki; Park, Jong Bae; Yoon, Jongwon; Kim, Bong-Joong; Sohn, Jung Inn; Lee, Young Boo; Bae, Tae-Sung; Chang, Sung-Jin; Huh, Yun Suk; Son, Byoungchul; Stach, Eric A; Lee, Takhee; Welland, Mark E

    2013-04-10

    We report a morphotropic phase transformation in vanadium dioxide (VO2) nanobeams annealed in a high-pressure hydrogen gas, which leads to the stabilization of metallic phases. Structural analyses show that the annealed VO2 nanobeams are hexagonal-close-packed structures with roughened surfaces at room temperature, unlike as-grown VO2 nanobeams with the monoclinic structure and with clean surfaces. Quantitative chemical examination reveals that the hydrogen significantly reduces oxygen in the nanobeams with characteristic nonlinear reduction kinetics which depend on the annealing time. Surprisingly, the work function and the electrical resistance of the reduced nanobeams follow a similar trend to the compositional variation due mainly to the oxygen-deficiency-related defects formed at the roughened surfaces. The electronic transport characteristics indicate that the reduced nanobeams are metallic over a large range of temperatures (room temperature to 383 K). Our results demonstrate the interplay between oxygen deficiency and structural/electronic phase transitions, with implications for engineering electronic properties in vanadium oxide systems.

  6. Electron affinity of cubic boron nitride terminated with vanadium oxide

    NASA Astrophysics Data System (ADS)

    Yang, Yu; Sun, Tianyin; Shammas, Joseph; Kaur, Manpuneet; Hao, Mei; Nemanich, Robert J.

    2015-10-01

    A thermally stable negative electron affinity (NEA) for a cubic boron nitride (c-BN) surface with vanadium-oxide-termination is achieved, and its electronic structure was analyzed with in-situ photoelectron spectroscopy. The c-BN films were prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition employing BF3 and N2 as precursors. Vanadium layers of ˜0.1 and 0.5 nm thickness were deposited on the c-BN surface in an electron beam deposition system. Oxidation of the metal layer was achieved by an oxygen plasma treatment. After 650 °C thermal annealing, the vanadium oxide on the c-BN surface was determined to be VO2, and the surfaces were found to be thermally stable, exhibiting an NEA. In comparison, the oxygen-terminated c-BN surface, where B2O3 was detected, showed a positive electron affinity of ˜1.2 eV. The B2O3 evidently acts as a negatively charged layer introducing a surface dipole directed into the c-BN. Through the interaction of VO2 with the B2O3 layer, a B-O-V layer structure would contribute a dipole between the O and V layers with the positive side facing vacuum. The lower enthalpy of formation for B2O3 is favorable for the formation of the B-O-V layer structure, which provides a thermally stable surface dipole and an NEA surface.

  7. Response of soil microbial activities and microbial community structure to vanadium stress.

    PubMed

    Xiao, Xi-Yuan; Wang, Ming-Wei; Zhu, Hui-Wen; Guo, Zhao-Hui; Han, Xiao-Qing; Zeng, Peng

    2017-08-01

    High levels of vanadium (V) have long-term, hazardous impacts on soil ecosystems and biological processes. In the present study, the effects of V on soil enzymatic activities, basal respiration (BR), microbial biomass carbon (MBC), and the microbial community structure were investigated through 12-week greenhouse incubation experiments. The results showed that V content affected soil dehydrogenase activity (DHA), BR, and MBC, while urease activity (UA) was less sensitive to V stress. The average median effective concentration (EC 50 ) thresholds of V were predicted using a log-logistic dose-response model, and they were 362mgV/kg soil for BR and 417mgV/kg soil for DHA. BR and DHA were more sensitive to V addition and could be used as biological indicators for soil V pollution. According to a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, the structural diversity of the microbial community decreased for soil V contents ranged between 254 and 1104mg/kg after 1 week of incubation. As the incubation time increased, the diversity of the soil microbial community structure increased for V contents ranged between 354 and 1104mg/kg, indicating that some new V-tolerant bacterial species might have replicated under these conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Structure formation of 5083 alloy during friction stir welding

    NASA Astrophysics Data System (ADS)

    Zaikina, A. A.; Kolubaev, A. V.; Sizova, O. V.; Ivanov, K. V.; Filippov, A. V.; Kolubaev, E. A.

    2017-12-01

    This paper provides a comparative study of structures obtained by friction stir welding and sliding friction of 5083 Al alloy. Optical and electron microscopy reveals identical fine-grained structures with a grain size of ˜5 µm both in the weld nugget zone and subsurface layer in friction independently of the initial grain size of the alloy. It has been suggested that the grain boundary sliding is responsible for the specific material flow pattern in both techniques considered.

  9. Synthesis, structural and optical properties of nanocrystalline vanadium doped zinc oxide aerogel

    NASA Astrophysics Data System (ADS)

    El Ghoul, J.; Barthou, C.; El Mir, L.

    2012-06-01

    We report the synthesis of vanadium-doped ZnO nanoparticles prepared by a sol-gel processing technique. In our approach, the water for hydrolysis was slowly released by esterification reaction followed by a supercritical drying in ethyl alcohol. Vanadium doping concentration of 10 at% has been investigated. After treatment in air at different temperatures, the obtained nanopowder was characterized by various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence (PL). Analysis by scanning electron microscopy at high resolution shows that the grain size increases with increasing temperature. Thus, in the case of thermal treatment at 500 °C in air, the powder with an average particle size of 25 nm shows a strong luminescence band in the visible range. The intensity and energy position of the obtained PL band depends on the temperature measurement increase. The mechanism of this emission band is discussed.

  10. VANADIUM CHEMISTRY ESSENTIALS FOR TREATMENT STUDIES

    EPA Science Inventory

    The importance of vanadium occurrence and treatment in drinking water has been elevated by its inclusion in the Contaminant Candidate List. Though it is still too early to know the nature of new regulatory requirements for vanadium, if indeed it becomes regulated, a substantial u...

  11. Structure and magnetic properties of nanostructured MnNi alloys fabricated by mechanical alloying and annealing treatments

    NASA Astrophysics Data System (ADS)

    Jalal, T.; Hossein Nedjad, S.; Khalili Molan, S.

    2013-05-01

    A nearly equiatomic MnNi alloy was fabricated from the elemental powders by means of mechanical alloying in a planetary ball milling apparatus. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and measurements of magnetization were conducted to identify the structural states and properties of the prepared alloys. After ball milling for 20 h, a disordered face-centered cubic (f.c.c.) solid solution was formed which increased in lattice parameter by further milling up to 50 h. An exothermic reaction took place at around 300-400°C during continuous heating of the disordered f.c.c. solid solution. This reaction is attributed to a structural ordering leading to the formation of a face-centered tetragonal (f.c.t.) phase with L10 type ordering. Examination of the magnetic properties indicated that the structural ordering increases remnant magnetization and decreases coerecivity.

  12. Method of preparing copper-dendritic composite alloys for mechanical reduction

    DOEpatents

    Verhoeven, J.D.; Gibson, E.D.; Schmidt, F.A.; Spitzig, W.A.

    1988-09-13

    Copper-dendritic composite alloys are prepared for mechanical reduction to increase tensile strength by dispersing molten droplets of the composite alloy into an inert gas; solidifying the droplets in the form of minute spheres or platelets; and compacting a mass of the spheres or platelets into an integrated body. The spheres preferably have diameters of from 50 to 2,000 [mu]m, and the platelets thicknesses of 100 to 2,000 [mu]m. The resulting spheres or platelets will contain ultra-fine dendrites which produce higher strengths on mechanical reduction of the bodies formed therefrom, or comparable strengths at lower reduction values. The method is applicable to alloys of copper with vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron and cobalt. 3 figs.

  13. Structural Changes in the Vanadium Sample Surface Induced by Pulsed High-Temperature Deuterium Plasma and Deuterium Ion Fluxes

    NASA Astrophysics Data System (ADS)

    Borovitskaya, I. V.; Pimenov, V. N.; Gribkov, V. A.; Padukh, M.; Bondarenko, G. G.; Gaidar, A. I.; Paramonova, V. V.; Morozov, E. V.

    2017-11-01

    The structural changes in the vanadium sample surface are studied as functions of the conditions of irradiation by pulsed high-temperature deuterium plasma and deuterium ion fluxes in the Plasma Focus installation. It is found that processes of partial evaporation, melting, and crystallization of the surface layer of vanadium samples take place in the plasma flux power density range q = 108-1010 W/cm2 and the ion flux density range q = 1010-1012 W/cm2. The surface relief is wavelike. There are microcracks, gas-filled bubbles (blisters), and traces of fracture on the surface. The blisters are failed in the solid state. The character of blister fracture is similar to that observed during usual ion irradiation in accelerators. The samples irradiated at relatively low power density ( q = 107-108 W/cm2) demonstrate the ejection of microparticles (surface fragments) on the side facing plasma. This process is assumed to be due to the fact that the unloading wave formed in the sample-target volume reaches its irradiated surface. Under certain irradiation conditions (sample-anode distance, the number of plasma pulses), a block microstructure with block sizes of several tens of microns forms on the sample surfaces. This structure is likely to form via directional crack propagation upon cooling of a thin melted surface layer.

  14. Structure and properties of stir-cast zinc alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    LeHuy, H.; Blain J.; Masounave, J.

    Stir casting (or rheocasting) of ZA-27 zinc alloys was investigated experimentally. By vigorously agitating the alloys during cooling, the dendrites that were forming were fragmented giving a unique structure composed of spherical and rosette shaped particles suspended in the remaining liquid. Under high shear rates ({center dot}{gamma} = 300s{sup {minus}1} or more) the slurries with primary particle concentrations as high as 60% displayed viscosities as low as 20 poises and could easily be casted. The effects of processing variables such as shearing and cooling rates and casting temperatures were studied. Their relative importance on the rheological and microstructural behavior ofmore » the stir cast alloys are discussed. Results from viscosity measurements on slurries show that non-dendritical ZA-27 alloys obey a power law fluid model. Finally, results from mechanical and compressive studies carried out on solidified slurries are discussed and compared to conventional casted and wrought alloy properties.« less

  15. Aqueous vanadium ion dynamics relevant to bioinorganic chemistry: A review.

    PubMed

    Kustin, Kenneth

    2015-06-01

    Aqueous solutions of the four highest vanadium oxidation states exhibit four diverse colors, which only hint at the diverse reactions that these ions can undergo. Cationic vanadium ions form complexes with ligands; anionic vanadium ions form complexes with ligands and self-react to form isopolyanions. All vanadium species undergo oxidation-reduction reactions. With a few exceptions, elucidation of the dynamics of these reactions awaited the development of fast reaction techniques before the kinetics of elementary ligation, condensation, reduction, and oxidation of the aqueous vanadium ions could be investigated. As the biological roles played by endogenous and therapeutic vanadium expand, it is appropriate to bring the results of the diverse kinetics studies under one umbrella. To achieve this goal this review presents a systematic examination of elementary aqueous vanadium ion dynamics. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Vanadium hydride deuterium-tritium generator

    DOEpatents

    Christensen, L.D.

    1980-03-13

    A pressure controlled vanadium hydride gas generator was designed to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

  17. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Scully, John R.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.; Wert, John A.

    1993-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program continues a high level of activity. Progress achieved between 1 Jan. and 30 Jun. 1993 is reported. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The following projects are addressed: environmental fatigue of Al-Li-Cu alloys; mechanisms of localized corrosion and environmental fracture in Al-Cu-Li-Mg-Ag alloy X2095 and compositional variations; the effect of zinc additions on the precipitation and stress corrosion cracking behavior of alloy 8090; hydrogen interactions with Al-Li-Cu alloy 2090 and model alloys; metastable pitting of aluminum alloys; cryogenic fracture toughness of Al-Cu-Li + In alloys; the fracture toughness of Weldalite (TM); elevated temperature cracking of advanced I/M aluminum alloys; response of Ti-1100/SCS-6 composites to thermal exposure; superplastic forming of Weldalite (TM); research to incorporate environmental effects into fracture mechanics fatigue life prediction codes such as NASA FLAGRO; and thermoviscoplastic behavior.

  18. Effects of Vanadium-Containing Compounds on Membrane Lipids and on Microdomains Used in Receptor-Mediated Signaling

    PubMed Central

    Roess, Deborah A.; Smith, Steven M. L.; Winter, Peter; Zhou, Jun; Dou, Ping; Baruah, Bharat; Trujillo, Alejandro M.; Levinger, Nancy E.; Yang, Xioda; Barisas, B. George; Crans, Debbie C.

    2011-01-01

    There is increasing evidence for the involvement of plasma membrane microdomains in insulin receptor function. Moreover, disruption of these structures, which are typically enriched in sphingomyelin and cholesterol, results in insulin resistance. Treatment strategies for insulin resistance include the use of vanadium compounds which have been shown in animal models to enhance insulin responsiveness. One possible mechanism for insulin-enhancing effects might involve direct effects of vanadium compounds on membrane lipid organization. These changes in lipid organization promote the partitioning of insulin receptors and other receptors into membrane microdomains where receptors are optimally functional. To explore this possibility, we have used several strategies involving vanadium complexes such as [VO2dipic]− (pyridin-2,6-dicarboxylatodioxovanadium(V)), decavanadate (V10O286−, V10), BMOV (bis(maltolato)oxovanadium(IV)) and [VO(saltris)]2 (2-salicylideniminato-2-(hydroxymethyl)-1,3-dihydroxypropane-oxovanadium(V)). Our strategies include an evaluation of interactions between vanadium-containing compounds and model lipid systems, an evaluation of the effects of vanadium compounds on lipid fluidity in erythrocyte membranes, and studies of the effects of vanadium-containing compounds on signaling events initiated by receptors known to use membrane microdomains as signaling platforms. PMID:18729092

  19. Development of Coatings for Tantalum Alloy Nozzle Vanes

    NASA Technical Reports Server (NTRS)

    Stetson, A. R.; Wimber, R. T.

    1967-01-01

    A group of silicide coatings developed for the T222 tantalum-base alloy have afforded over 600 hours of protection at 1600 and 2400 F during cyclic exposure in air. These coatings were applied in two steps. A modifier alloy was applied by slurry techniques and was sintered in vacuum prior to siliciding by pack cementation in argon. Application of the modifier alloy by pack cementation was found to be much less effective. The addition of titanium and vanadium to molybdenum and tungsten yielded beneficial modifier alloys, whereas the addition of chromium showed no improvement. After siliciding, the 15Ti- 35W-15V-35Mo modifier alloy exhibited the best performance; one sample survived 1064 hours of oxidation at 2400 F. This same coating was the only coating to reproducibly provide 600 hours of protection at both 1600 and 2400 F; in the second and third of three experiments, involving oxidation of three to five specimens at each temperature in each experiment, no failures were observed in 600 hours of testing. The slurry coatings were also shown to protect the Cb752 and D43 columbium-base alloys.

  20. Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B2O3-Li2O-ZnO-V2O5 Glasses.

    PubMed

    Arya, S K; Danewalia, S S; Arora, Manju; Singh, K

    2016-12-01

    In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V 4+ state, having a tetragonal symmetry. As the glass composition of V 2 O 5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V 4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10 -5 S cm -1 at 250 °C for the glass with 2.5 mol % V 2 O 5 . Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.

  1. Vanadium-pumped titanium x-ray laser

    DOEpatents

    Nilsen, J.

    1992-05-26

    A resonantly photo-pumped x-ray laser is formed of a vanadium and titanium foil combination that is driven by two beams of intense line focused optical laser radiation. Ground state neon-like titanium ions are resonantly photo-pumped by line emission from fluorine-like vanadium ions. 4 figs.

  2. Graphene-modified nanostructured vanadium pentoxide hybrids with extraordinary electrochemical performance for Li-ion batteries

    DOE PAGES

    Liu, Qi; Li, Zhe-Fei; Liu, Yadong; ...

    2015-01-20

    The long-standing issues of low intrinsic electronic conductivity, slow lithium-ion diffusion and irreversible phase transitions on deep discharge prevent the high specific capacity/energy (443 mAh g -1 and 1,550 Wh kg -1) vanadium pentoxide from being used as the cathode material in practical battery applications. Here we develop a method to incorporate graphene sheets into vanadium pentoxide nanoribbons via the sol–gel process. The resulting graphene-modified nanostructured vanadium pentoxide hybrids contain only 2 wt. % graphene, yet exhibits extraordinary electrochemical performance: a specific capacity of 438 mAh g -1, approaching the theoretical value (443 mAh g -1), a long cyclability andmore » significantly enhanced rate capability. Such performance is the result of the combined effects of the graphene on structural stability, electronic conduction, vanadium redox reaction and lithium-ion diffusion supported by various experimental studies. Finally, this method provides a new avenue to create nanostructured metal oxide/graphene materials for advanced battery applications.« less

  3. Mineralogy and geochemistry of vanadium in the Colorado Plateau

    USGS Publications Warehouse

    Weeks, A.D.

    1961-01-01

    The chief domestic source of vanadium is uraniferous sandstone in the Colorado Plateau. Vanadium is 3-, 4-, or 5-valent in nature and, as oxides or combined with other elements, it forms more than 40 minerals in the Plateau ores. These ores have been studied with regard to the relative amounts of vanadium silicates and oxide-vanadates, uranium-vanadium ratios, the progressive oxidation of black low-valent ores to high-valent carnotite-type ores, and theories of origin. ?? 1961.

  4. Aluminum alloy material structure impact localization by using FBG sensors

    NASA Astrophysics Data System (ADS)

    Zhu, Xiubin

    2014-12-01

    The aluminum alloy structure impact localization system by using fiber Bragg grating (FBG) sensors and impact localization algorithm was investigated. A four-FBG sensing network was established. And the power intensity demodulation method was initialized employing the narrow-band tunable laser. The wavelet transform was used to weaken the impact signal noise. And the impact signal time difference was extracted to build the time difference localization algorithm. At last, a fiber Bragg grating impact localization system was established and experimentally verified. The experimental results showed that in the aluminum alloy plate with the 500 mm*500 mm*2 mm test area, the maximum and average impact abscissa localization errors were 11 mm and 6.25 mm, and the maximum and average impact ordinate localization errors were 9 mm and 4.25 mm, respectively. The fiber Bragg grating sensors and demodulation system are feasible to realize the aviation aluminum alloy material structure impact localization. The research results provide a reliable method for the aluminum alloy material structure impact localization.

  5. Molten salt corrosion of heat resisting alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wong-Moreno, A.; Salgado, R.I.M.; Martinez, L.

    1995-09-01

    This paper is devoted to the study of the corrosion behavior of eight high chromium alloys exposed to three different oil ash deposits with V/(Na+S) atomic ratios 0.58, 2.05 and 13.43, respectively. The alloys were exposed to ash deposits at 750 and 900 C; in this temperature range some deposit constituents have reached their melting point developing a molten salt corrosion process. The group of alloys tested included four Fe-Cr-Ni steels UNS specifications S304000, S31000, N08810 and N08330; two Fe-Cr alloys, UNS S44600 and alloy MA 956; and two Ni-base alloys, UNS N06333 and UNS N06601. The deposits and themore » exposed surfaces were characterized by chemical analysis, XRD, DTA, SEM and x-ray microanalysis. The oil-ash corrosion resistance of alloys is discussed in terms of the characteristics of corrosion product scales, which are determined by interaction between the alloy and the corrosive environment. All the alloys containing nickel exhibited sulfidation when were exposed at 750 C, but at 900 C only those without aluminum presented sulfidation or sulfidation and oxidation, while the alloys containing aluminum only exhibited internal oxidation. In spite of good resistance to corrosion by oil-ash deposits, 446-type alloy might not be suitable for temperatures higher than 750 C because of embrittlement caused by excessive sigma-phase precipitation. Alloy MA956 showed highest corrosion resistance at 900 C to oil-ash deposits with high vanadium content.« less

  6. Vanadium bioavailability and toxicity to soil microorganisms and plants.

    PubMed

    Larsson, Maja A; Baken, Stijn; Gustafsson, Jon Petter; Hadialhejazi, Golshid; Smolders, Erik

    2013-10-01

    Vanadium, V, is a redox-sensitive metal that in solution, under aerobic conditions, prevails as the oxyanion vanadate(V). There is little known regarding vanadium toxicity to soil biota, and the present study was set up to determine the toxicity of added vanadate to soil organisms and to investigate the relationship between toxicity and vanadium sorption in soils. Five soils with contrasting properties were spiked with 7 different doses (3.2-3200 mg V kg(-1)) of dissolved vanadate, and toxicity was measured with 2 microbial and 3 plant assays. The median effective concentration (EC50) thresholds of the microbial assays ranged from 28 mg added V kg(-1) to 690 mg added V kg(-1), and the EC50s in the plant assays ranged from 18 mg added V kg(-1) to 510 mg added V kg(-1). The lower thresholds were in the concentration range of the background vanadium in the untreated control soils (15-58 mg V kg(-1)). The vanadium toxicity to plants decreased with a stronger soil vanadium sorption strength. The EC50 values for plants expressed on a soil solution basis ranged from 0.8 mg V L(-1) to 15 mg V L(-1) and were less variable among soils than corresponding values based on total vanadium in soil. It is concluded that sorption decreases the toxicity of added vanadate and that soil solution vanadium is a more robust measure to determine critical vanadium concentrations across soils. © 2013 SETAC.

  7. Vanadium and columbium additions in pressure vessel steels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, P.; Somers, B.R.; Pense, A.W.

    1994-09-01

    A statistically designed series of vanadium and columbium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in post weld heat treated (PWHT) multi-pass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the columbium additions were in the range 0.004 to 0.06 Wt.% GMAW processes with welding heat inputs of 3kJ/mm and 5kJ/mm and post-weld heat treatments at 620 C for 2 10 hours were employed. A degradation of the HAZ toughness with additions of microalloy elements V and Cb in the as-welded and PWHT conditions was revealed. The 50more » Joule (37 ft-lb) transition temperature (TT50J) for HAZs in all weld conditions correlated with maximum HAZ hardness. Increases in HAZ hardness and TT50J caused by PWHT were observed. Hence PWHT in some situations may not beneficial for V/Cb microalloyed HLSA steels. The randomly distributed precipitation of V and Cb carbides (V, Cb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5--15 nm, is the predominant alloy carbide precipitate morphology in these steels. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality, mid-specimen location to an off center higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel.« less

  8. Structural characteristics and elevated temperature mechanical properties of AJ62 Mg alloy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kubásek, J., E-mail: Jiri.Kubasek@vscht.cz; Vojtěch, D.; Martínek, M.

    2013-12-15

    Structure and mechanical properties of the novel casting AJ62 (Mg–6Al–2Sr) alloy developed for elevated temperature applications were studied. The AJ62 alloy was compared to commercial casting AZ91 (Mg–9Al–1Zn) and WE43 (Mg–4Y–3RE) alloys. The structure was examined by scanning electron microscopy, x-ray diffraction and energy dispersive spectrometry. Mechanical properties were characterized by Viskers hardness measurements in the as-cast state and after a long-term heat treatment at 250 °C/150 hours. Compressive mechanical tests were also carried out both at room and elevated temperatures. Compressive creep tests were conducted at a temperature of 250 °C and compressive stresses of 60, 100 and 140more » MPa. The structure of the AJ62 alloy consisted of primary α-Mg dendrites and interdendritic nework of the Al{sub 4}Sr and massive Al{sub 3}Mg{sub 13}Sr phases. By increasing the cooling rate during solidification from 10 and 120 K/s the average dendrite arm thickness decreased from 18 to 5 μm and the total volume fraction of the interdendritic phases from 20% to 30%. Both factors slightly increased hardness and compressive strength. The room temperature compressive strength and hardness of the alloy solidified at 30 K/s were 298 MPa and 50 HV 5, i.e. similar to those of the as-cast WE43 alloy and lower than those of the AZ91 alloy. At 250 °C the compressive strength of the AJ62 alloy decreased by 50 MPa, whereas those of the AZ91 and WE43 alloys by 100 and 20 MPa, respectively. The creep rate of the AJ62 alloy was higher than that of the WE43 alloy, but significantly lower in comparison with the AZ91 alloy. Different thermal stabilities of the alloys were discussed and related to structural changes during elevated temperature expositions. - Highlights: • Small effect of cooling rate on the compressive strength and hardness of AJ 62 • A bit lower compressive strength of AJ 62 compared to AZ91 at room temperature • Higher resistance of the AJ

  9. Electronic structure of alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ehrenreich, H.; Schwartz, L.M.

    1976-01-01

    The description of electronic properties of binary substitutional alloys within the single particle approximation is reviewed. Emphasis is placed on a didactic exposition of the equilibrium properties of the transport and magnetic properties of such alloys. Topics covered include: multiple scattering theory; the single band alloy; formal extensions of the theory; the alloy potential; realistic model state densities; the s-d model; and the muffin tin model. 43 figures, 3 tables, 151 references. (GHT)

  10. Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

    PubMed

    Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

    2017-11-05

    In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

  11. Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

    PubMed Central

    Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

    2017-01-01

    In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics. PMID:29113096

  12. Effect of vanadium compounds on acid phosphatase activity.

    PubMed

    Vescina, C M; Sálice, V C; Cortizo, A M; Etcheverry, S B

    1996-01-01

    The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activity seems to depend on the geometry around the vanadium atom more than on the oxidation state. Our results indicate a correlation between the PTPase activity and the sensitivity to vanadate and vanadyl cation.

  13. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  14. Metal Insulator transition in Vanadium Dioxide

    NASA Astrophysics Data System (ADS)

    Jovaini, Azita; Fujita, Shigeji; Suzuki, Akira; Godoy, Salvador

    2012-02-01

    MAR12-2011-000262 Abstract Submitted for the MAR12 Meeting of The American Physical Society Sorting Category: 03.9 (T) On the metal-insulator-transition in vanadium dioxide AZITA JOVAINI, SHIGEJI FUJITA, University at Buffalo, SALVADOR GODOY, UNAM, AKIRA SUZUKI, Tokyo University of Science --- Vanadium dioxide (VO2) undergoes a metal-insulator transition (MIT) at 340 K with the structural change from tetragonal to monoclinic crystal. The conductivity _/ drops at MIT by four orders of magnitude. The low temperature monoclinic phase is known to have a lower ground-state energy. The existence of the k-vector k is prerequisite for the conduction since the k appears in the semiclassical equation of motion for the conduction electron (wave packet). The tetragonal (VO2)3 unit is periodic along the crystal's x-, y-, and z-axes, and hence there is a three-dimensional k-vector. There is a one-dimensional k for a monoclinic crystal. We believe this difference in the dimensionality of the k-vector is the cause of the conductivity drop. Prefer Oral Session X Prefer .

  15. 77 FR 51825 - Ferrovanadium and Nitrided Vanadium From Russia

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-27

    ... Nitrided Vanadium From Russia Determination On the basis of the record \\1\\ developed in the subject five... order on ferrovanadium and nitrided vanadium from Russia would not be likely to lead to continuation or... in USITC Publication 4345 (August 2012), entitled Ferrovanadium and Nitrided Vanadium from Russia...

  16. Chloride supporting electrolytes for all-vanadium redox flow batteries.

    PubMed

    Kim, Soowhan; Vijayakumar, M; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Chen, Feng; Hu, Jianzhi; Li, Liyu; Yang, Zhenguo

    2011-10-28

    This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the solutions over a wide temperature range. The all-vanadium redox flow batteries with the chloride electrolytes demonstrated excellent reversibility and fairly high efficiencies. Only negligible, if any, gas evolution was observed. The improved energy capacity and good performance, along with the ease in heat management, would lead to substantial reduction in capital cost and life-cycle cost, making the vanadium chloride redox flow battery a promising candidate for stationary applications. This journal is © the Owner Societies 2011

  17. Recycling of Ammonia Wastewater During Vanadium Extraction from Shale

    NASA Astrophysics Data System (ADS)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-03-01

    In the vanadium metallurgical industry, massive amounts of ammonia hydroxide or ammonia salt are added during the precipitation process to obtain V2O5; therefore, wastewater containing a high level of NH4 + is generated, which poses a serious threat to environmental and hydrologic safety. In this article, a novel process was developed to recycle ammonia wastewater based on a combination of ammonia wastewater leaching and crystallization during vanadium extraction from shale. The effects of the NH4 + concentration, temperature, time and liquid-to-solid ratio on the leaching efficiencies of vanadium, aluminum and potassium were investigated, and the results showed that 93.2% of vanadium, 86.3% of aluminum and 96.8% of potassium can be leached from sulfation-roasted shale. Subsequently, 80.6% of NH4 + was separated from the leaching solution via cooling crystallization. Vanadium was recovered via a combined method of solvent extraction, precipitation and calcination. Therefore, ammonia wastewater was successfully recycled during vanadium extraction from shale.

  18. Mechanical Properties of Gradient Structure Mg Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Hongliang; Yang, Jiang; Zhou, Hao; Moering, Jordan; Yin, Zhe; Gong, Yulan; Zhao, KunYu

    2017-09-01

    In this work, a surface mechanical attrition treatment (SMAT) process was applied to AZ31B magnesium alloy at room temperature. This method produced a gradient structure on the treated AZ31B, in which the grains of the topmost layer are refined to nanoscale sizes. A combination of nanocrystallites at the surface and coarse-grains in the center are the main features of this structure. This structure results in an excellent combination of both strength and ductility. The highest yield strength for the 30 minutes SMAT AZ31B samples increased to 249 ± 5 MPa and the uniform elongation decreased to 9.3 ± 0.8 pct, whereas the original yield strength was only 147 ± 4 MPa and the uniform elongation was 15.4 ± 1.1 pct. Microstructural observations, stress relaxation tests, and hardness tests were used to verify the results. Additionally, there is a specific volume fraction of gradient structure to achieve the best mechanical performance, which is shown to be in the range of 9.3 to 14 pct for the AZ31B alloy.

  19. Vanadium pentoxide

    Integrated Risk Information System (IRIS)

    Vanadium pentoxide ; CASRN 1314 - 62 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogen

  20. First-principles investigations of iron-based alloys and their properties

    NASA Astrophysics Data System (ADS)

    Limmer, Krista Renee

    Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys. Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VCx, were calculated to provide insight for the carbide formation and stability. Carbon vacancy defects are shown to stabilize the bulk carbide due to increased V-V bonding in addition to localized increased V-C bond strength. The VCx (100) surface energy is minimized when carbon vacancies are at least two layers from the surface. Further, the Fe/VC interface is stabilized through maintaining stoichiometry at the Fe/VC interface. Intrinsic and unstable stacking fault energy, gammaisf and gamma usf respectively, were explicitly calculated in nonmagnetic fcc Fe-X systems for X = Al, Si, P, S, and the 3d and 4d transition elements. A parabolic relationship is observed in gamma isf across the transition metals with minimums observed for Mn and Tc in the 3d and 4d periods, respectively. Mn is the only alloying addition that was shown to decrease gamma isf in fcc Fe at the given concentration. The effect of alloying on gammausf also has a parabolic relationship, with all additions decreasing gammaisf yielding maximums for Fe and Rh.

  1. Three-Dimensional Cellular Structures Enhanced By Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Nathal, Michael V.; Krause, David L.; Wilmoth, Nathan G.; Bednarcyk, Brett A.; Baker, Eric H.

    2014-01-01

    This research effort explored lightweight structural concepts married with advanced smart materials to achieve a wide variety of benefits in airframe and engine components. Lattice block structures were cast from an aerospace structural titanium alloy Ti-6Al-4V and a NiTi shape memory alloy (SMA), and preliminary properties have been measured. A finite element-based modeling approach that can rapidly and accurately capture the deformation response of lattice architectures was developed. The Ti-6-4 and SMA material behavior was calibrated via experimental tests of ligaments machined from the lattice. Benchmark testing of complete lattice structures verified the main aspects of the model as well as demonstrated the advantages of the lattice structure. Shape memory behavior of a sample machined from a lattice block was also demonstrated.

  2. Evolution dependence of vanadium nitride nanoprecipitates on directionality of ion irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tan, L.; Kim, B. K.; Was, G. S.

    The influence of the directionality of Fe 2+ ion irradiation on the evolution of vanadium nitride platelet–shaped nanoprecipitates at 500 °C was investigated in this paper in a ferritic alloy using transmission electron microscopy. When the ion-irradiation direction was approximately aligned with the initial particle length, particles grew longer and sectioned into shorter lengths at higher doses, resulting in increased particle densities. As ion-irradiation direction deviated from particle-length direction, some particles sectioned lengthwise and then dissolved, resulting in decreased particle densities. Surviving particles were transformed into parallelograms with a different orientation relationship with the matrix. Finally, nanoprecipitate evolution dependence onmore » beam-nanoprecipitate orientation is a process that may be different from reactor irradiation.« less

  3. Evolution dependence of vanadium nitride nanoprecipitates on directionality of ion irradiation

    DOE PAGES

    Tan, L.; Kim, B. K.; Was, G. S.

    2017-09-06

    The influence of the directionality of Fe 2+ ion irradiation on the evolution of vanadium nitride platelet–shaped nanoprecipitates at 500 °C was investigated in this paper in a ferritic alloy using transmission electron microscopy. When the ion-irradiation direction was approximately aligned with the initial particle length, particles grew longer and sectioned into shorter lengths at higher doses, resulting in increased particle densities. As ion-irradiation direction deviated from particle-length direction, some particles sectioned lengthwise and then dissolved, resulting in decreased particle densities. Surviving particles were transformed into parallelograms with a different orientation relationship with the matrix. Finally, nanoprecipitate evolution dependence onmore » beam-nanoprecipitate orientation is a process that may be different from reactor irradiation.« less

  4. Anion-conductive membranes with ultralow vanadium permeability and excellent performance in vanadium flow batteries.

    PubMed

    Mai, Zhensheng; Zhang, Huamin; Zhang, Hongzhang; Xu, Wanxing; Wei, Wenping; Na, Hui; Li, Xianfeng

    2013-02-01

    Anion exchange membranes prepared from quaternized poly(tetramethyl diphenyl ether sulfone) (QAPES) were first investigated in the context of vanadium flow battery (VFB) applications. The membranes showed an impressive suppression effect on vanadium ions. The recorded vanadium permeability was 0.02×10(-7)-0.09×10(-7) cm(2) min(-1), which was two orders of magnitude lower than that of Nafion 115. The self-discharge duration of a VFB single cell with a QAPES membrane is four times longer than that of Nafion 115. The morphological difference in hydrophilic domains between QAPES and Nafion was confirmed by TEM. After soaking the membranes in VO(2)(+) solution, adsorbed vanadium ions can barely be found in QAPES, whereas the hydrophilic domains of Nafion were stained. In the ex situ chemical stability test, QAPES showed a high tolerance to VO(2)(+) and remained intact after immersion in VO(2)(+) solution for over 250 h. The performance of a VFB single cell assembled with QAPES membranes is equal to or even better than that of Nafion 115 and remains stable in a long-term cycle test. These results indicate that QAPES membranes can be an ideal option in the fabrication of high-performance VFBs with low electric capacity loss. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Comparative erythropoietic effects of three vanadium compounds.

    PubMed

    Hogan, G R

    2000-07-10

    The biotoxic effects of vanadium are variable depending upon a number of factors including the oxidation state of the test compound. This study reports the effects of three vanadium compounds on peripheral erythrocytes. On day 0 female ICR mice received a single injection of vanadium chloride (V-III), vanadyl sulfate (V-IV), or sodium orthovandate (V-V). At scheduled intervals post-injection, the number of circulating erythrocytes [red blood cells per millimeter cubed (RBC/mm3)], reticulocyte percentages, and radioiron uptake percentages were determined and compared to mice receiving saline only. Data show that all three test substances promoted a significant lowering of RBC/mm3 beginning on day 1 for V-IV and V-V and on day 2 for V-III through day 4. The reticulocyte percentages increase followed the same time course as that of the peripheral RBC decrease. Peak reticulocytosis was noted on days 2 and 4 for all three vanadium-treated groups; for V-IV and V-V the increase continued to day 6. Radioiron data showed an erythropoietic stimulation by a significant increase in uptake percentages on days 4-6 after vanadium injections compared to saline-treated controls.

  6. Geochemical controls on vanadium accumulation in fossil fuels

    USGS Publications Warehouse

    Breit, G.N.; Wanty, R.B.

    1989-01-01

    High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

  7. Geochemical controls of vanadium accumulation in fossil fuels

    USGS Publications Warehouse

    Breit, G.N.; Wanty, R.B.

    1989-01-01

    High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

  8. IRIS Toxicological Review of Vanadium Pentoxide ...

    EPA Pesticide Factsheets

    On September 30, 2011, the draft Toxicological Review of Vanadium Pentoxide and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices before public release. In the new IRIS process (May 2009), introduced by the EPA Administrator, all written comments on IRIS assessments submitted by other federal agencies and White House Offices will be made publicly available. Accordingly, interagency comments and the interagency science consultation draft of the IRIS Toxicological Review of Vanadium Pentoxide and the charge to external peer reviewers are posted on this site. EPA is reassessing its IRIS toxicological review of vanadium pentoxide (CASRN 1314-62-1). This vanadium pentoxide reassessment consists of an oral reference dose (RfD), an inhalation reference concentration (RfC), an inhalation unit risk (IUR) and a cancer weight of evidence descriptor. This is the first assessment developing an RfC or IUR for this compound. This assessment is intended to provide human health data to support agency regulatory decisions.

  9. Analysis of the Defect Structure of B2 Feal Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John; Noebe, Ronald D.; Amador, Carlos

    1995-01-01

    The Bozzolo, Ferrante and Smith (BFS) method for alloys is applied to the study of the defect structure of B2 FeAI alloys. First-principles Linear Muffin Tin Orbital calculations are used to determine the input parameters to the BFS method used in this work. The calculations successfully determine the phase field of the B2 structure, as well as the dependence with composition of the lattice parameter. Finally, the method is used to perform 'static' simulations where instead of determining the ground state configuration of the alloy with a certain concentration of vacancies, a large number of candidate ordered structures are studied and compared, in order to determine not only the lowest energy configurations but other possible metastable states as well. The results provide a description of the defect structure consistent with available experimental data. The simplicity of the BFS method also allows for a simple explanation of some of the essential features found in the concentration dependence of the heat of formation, lattice parameter and the defect structure.

  10. Elucidating the Higher Stability of Vanadium (V) Cations in Mixed Acid Based Redox Flow Battery Electrolytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vijayakumar, M.; Wang, Wei; Nie, Zimin

    2013-11-01

    The Vanadium (V) cation structures in mixed acid based electrolyte solution were analysed by density functional theory (DFT) based computational modelling and 51V and 35Cl Nuclear Magnetic Resonance (NMR) spectroscopy. The Vanadium (V) cation exists as di-nuclear [V2O3Cl2.6H2O]2+ compound at higher vanadium concentrations (≥1.75M). In particular, at high temperatures (>295K) this di-nuclear compound undergoes ligand exchange process with nearby solvent chlorine molecule and forms chlorine bonded [V2O3Cl2.6H2O]2+ compound. This chlorine bonded [V2O3Cl2.6H2O]2+ compound might be resistant to the de-protonation reaction which is the initial step in the precipitation reaction in Vanadium based electrolyte solutions. The combined theoretical and experimental approachmore » reveals that formation of chlorine bonded [V2O3Cl2.6H2O]2+ compound might be central to the observed higher thermal stability of mixed acid based Vanadium (V) electrolyte solutions.« less

  11. Vanadium fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser–solid experiments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Palmeri, P., E-mail: patrick.palmeri@umons.ac.be; Quinet, P., E-mail: pascal.quinet@umons.ac.be; IPNAS, Université de Liège, B-4000 Liège

    2015-09-15

    The K-shell electron impact ionization (EII) cross section, along with the K-shell fluorescence yield, is one of the key atomic parameters for fast-electron diagnostic in laser–solid experiments through the K-shell emission cross section. In addition, in a campaign dedicated to the modeling of the K lines of astrophysical interest (Palmeri et al. (2012)), the K-shell fluorescence yields for the K-vacancy fine-structure atomic levels of all the vanadium isonuclear ions have been calculated. In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent vanadium ions to the daughter ions K-vacancy levels considered in Palmerimore » et al. (2012) have been determined. The relativistic distorted-wave (DW) approximation implemented in the FAC atomic code has been used for the incident electron kinetic energies up to 20 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic behavior of the modified relativistic binary encounter Bethe model (MRBEB) of Guerra et al. (2012) with the density-effect correction proposed by Davies et al. (2013)« less

  12. Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy

    DOE PAGES

    Zhang, F. X.; Zhao, Shijun; Jin, Ke; ...

    2017-05-19

    Multi-element solid solution alloys are intrinsically disordered on the atomic scale, and many of their advanced properties originate from the unique local structural characteristics. We measured the local structure of a NiCoCr solid solution alloy with X-ray/neutron total scattering and extended X-ray absorption fine structure (EXAFS) techniques. The atomic pair distribution function analysis (PDF) did not exhibit distinct structural distortion. But, EXAFS analysis suggested that the Cr atoms are favorably bonded with Ni and Co in the solid solution alloys. This short-range order (SRO) plays a role in the distinct low values of electrical and thermal conductivities in Ni-based solidmore » solution alloys when Cr is incorporated. Both the long-range and local structures of the NiCoCr alloy upon Ni ion irradiation were studied and an irradiation-induced enhancement of SRO was found.« less

  13. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  14. Vanadium-pumped titanium x-ray laser

    DOEpatents

    Nilsen, Joseph

    1992-01-01

    A resonantly photo-pumped x-ray laser (10) is formed of a vanadium (12) and titanium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state neon-like titanium ions (34) are resonantly photo-pumped by line emission from fluorine-like vanadium ions (32).

  15. Dynamically Switching the Polarization State of Light Based on the Phase Transition of Vanadium Dioxide

    NASA Astrophysics Data System (ADS)

    Jia, Zhi-Yong; Shu, Fang-Zhou; Gao, Ya-Jun; Cheng, Feng; Peng, Ru-Wen; Fan, Ren-Hao; Liu, Yongmin; Wang, Mu

    2018-03-01

    There have been great endeavors devoted to manipulating the polarization state of light by plasmonic nanostructures in recent decades. However, the topic of active polarizers has attracted much less attention. We present a composite plasmonic nanostructure consisting of vanadium dioxide that can dynamically modulate the polarization state of the reflected light through a thermally induced phase transition of vanadium dioxide. We design a system consisting of anisotropic plasmonic nanostructures with vanadium dioxide that exhibits distinct reflections subjected to different linearly polarized incidence at room temperature and in the heated state. Under a particular linearly polarized incidence, the polarization state of the reflected light changes at room temperature, and reverts to its original polarization state above the phase-transition temperature. The composite structure can also be used to realize a dynamically switchable infrared image, wherein a pattern can be visualized at room temperature while it disappears above the phase-transition temperature. The composite structure could be potentially used for versatile optical modulators, molecular detection, and polarimetric imaging.

  16. Kinetic model of whole-body vanadium metabolism: studies in sheep

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Patterson, B.W.; Hansard, S.L. II; Ammerman, C.B.

    1986-08-01

    A compartmental model for vanadium metabolism in sheep has been proposed. The model is consistent with data obtained from sheep fed a control diet (2.6 ppm vanadium) containing 0 or 200 ppm supplemental vanadium. Sheep were administered UYV dioxovanadium either orally or intravenously. Blood feces, and urine radioactivity were monitored for 6 days postdosing. Several new insights regarding vanadium metabolism are suggested and tested against the data using the model. Some of these include 1) significant absorption of UYV occurs from the upper gastrointestinal tract; 2) an in vivo process is necessary in order for UYV dioxovanadium to be convertedmore » into a more biologically reactive species; 3) at steady state the upper and lower gastrointestinal tracts contain at least 10- and 100-fold more mass of vanadium, respectively, than does blood. No statistically significant differences in transport rate constants were found between animals receiving 0 and 200 ppm supplemental dietary vanadium. The availability of a model will enable the refinement of future studies regarding vanadium metabolism in the ruminant.« less

  17. Microscopic structural change in a liquid Fe-C alloy of ~5 GPa

    DOE PAGES

    Shibazaki, Yuki; Kono, Yoshio; Fei, Yingwei

    2015-07-04

    The structure of a liquid Fe-3.5 wt% C alloy is examined for up to 7.2 GPa via multiangle energy-dispersive X-ray diffraction using a Paris-Edinburgh type large-volume press. X-ray diffraction data show clear changes in the pressure-dependent peak positions of structure factor and reduced pair distribution function at 5GPa. These results suggest that the liquid Fe-3.5wt%C alloys change structurally at approximately 5GPa. This finding serves as a microscopic explanation for the alloy’s previously observed density change at the same pressure. The pressure dependencies of the nearest and second neighbor distances of the liquid Fe-3.5 wt% C alloy are similar to thosemore » of liquid Fe which exhibits a structural change near the bcc-fcc-liquid triple point (5.2GPa and 1991 K). Here, similarities between Fe-3.5wt% C and Fe suggest that a density change also occurs in liquid Fe and that this structural change extends to other Fe-light element alloys.« less

  18. Colorimetric detection of hydrogen peroxide by dioxido-vanadium(V) complex containing hydrazone ligand: synthesis and crystal structure

    NASA Astrophysics Data System (ADS)

    Kurbah, Sunshine D.; Syiemlieh, Ibanphylla; Lal, Ram A.

    2018-03-01

    Dioxido-vanadium(V) complex has been synthesized in good yield, the complex was characterized by IR, UV-visible and 1H NMR spectroscopy. Single crystal X-ray crystallography techniques were used to assign the structure of the complex. Complex crystallized with monoclinic P21/c space group with cell parameters a (Å) = 39.516(5), b (Å) = 6.2571(11), c (Å) = 17.424(2), α (°) = 90, β (°) = 102.668(12) and γ (°) = 90. The hydrazone ligand is coordinate to metal ion in tridentate fashion through -ONO- donor atoms forming a distorted square pyramidal geometry around the metal ion.

  19. Effect of annealing on optical properties and structure of the vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Zhu, Huiqun; Li, Yi; Li, Yuming; Huang, Yize; Tong, Guoxiang; Fang, Baoying; Zheng, Qiuxin; Li, Liu; Shen, Yujian

    2012-10-01

    VO2 thin films were prepared on soda-lime glass substrates by DC magnetron sputtering at room temperature using vanadium target and post annealing in air. X-ray diffraction and FTIR spectroscopy analyses showed that the films obtained at the optimized parameters have high VO2 (011) orientation. Both low temperature deposition and post annealing method were beneficial to grow the nano-films with pure VO2 phase-structure and composition. Metalinsulator transition properties of the VO2 films in terms of infrared transmittance, transmittance variation and film thickness were investigated under varying annealing temperature. Results showed that infrared transmittance variation and transition temperature of the nano-films were significantly improved and reduced respectively. Therefore, this study was able to develop practical low-cost preparation methods for high-performance intelligent energy-saving thin films.

  20. Detection of structural changes and mechanical properties of light alloys after severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.

    2017-11-01

    Severe plastic deformation by equal channel angular pressing has been performed to produce light aluminum and magnesium alloy billets with ultrafine-grained structure. The physical and mechanical properties of the processed alloys are examined by studying their microstructure, measuring microhardness, yield strength, and uniaxial tensile strength. A nondestructive testing technique using three-dimensional X-ray tomography is proposed for detecting internal structural defects and monitoring damage formation in the structure of alloys subjected to severe plastic deformation. The investigation results prove the efficiency of the chosen method and selected mode of producing ultrafine-grained light alloys.

  1. Phase Stability and Transformations in Vanadium Oxide Nanocrystals

    NASA Astrophysics Data System (ADS)

    Bergerud, Amy Jo

    Vanadium oxides are both fascinating and complex, due in part to the many compounds and phases that can be stabilized as well as the phase transformations which occur between them. The metal to insulator transitions (MITs) that take place in vanadium oxides are particularly interesting for both fundamental and applied study as they can be induced by a variety of stimuli ( i.e., temperature, pressure, doping) and utilized in many applications (i.e., smart windows, sensors, phase change memory). Nanocrystals also tend to demonstrate interesting phase behavior, due in part to the enhanced influence of surface energy on material thermodynamics. Vanadium oxide nanocrystals are thus expected to demonstrate very interesting properties in regard to phase stability and phase transformations, although synthesizing vanadium oxides in nanocrystal form remains a challenge. Vanadium sesquioxide (V2O3) is an example of a material that undergoes a MIT. For decades, the low temperature monoclinic phase and high temperature corundum phase were the only known crystal structures of V2O3. However, in 2011, a new metastable polymorph of V2O3 was reported with a cubic, bixbyite crystal structure. In Chapter 2, a colloidal route to bixbyite V2O 3 nanocrystals is presented. In addition to being one of the first reported observations of the bixbyite phase in V2O3, it is also one of the first successful colloidal syntheses of any of the vanadium oxides. The nanocrystals possess a flower-like morphology, the size and shape of which are dependent on synthesis time and temperature, respectively. An aminolysis reaction mechanism is determined from Fourier transform infrared spectroscopy data and the bixbyite crystal structure is confirmed by Rietveld refinement of X-ray diffraction (XRD) data. Phase stability is assessed in both air and inert environments, confirming the metastable nature of the material. Upon heating in an inert atmosphere above 700°C, the nanocrystals irreversibly transform

  2. Superconducting and Magnetic Properties of Vanadium/iron Superlattices.

    NASA Astrophysics Data System (ADS)

    Wong, Hong-Kuen

    A novel ultrahigh vacuum evaporator was constructed for the preparation of superlattice samples. The thickness control was much better than an atomic plane. With this evaporator we prepared V/Fe superlattice samples on (0001) sapphire substrates with different thicknesses. All samples showed a good bcc(110) structure. Mossbauer experiments showed that the interface mixing extended a distance of about one atomic plane indicating an almost rectangular composition profile. Because of this we were able to prepare samples with layer thickness approaching one atomic plane. Even with ultrathin Fe layers, the samples are ferromagnetic, at least at lower temperatures. Superparamagnetism and spin glass states were not seen. In the absence of an external field, the magnetic moments lie close to the film plane. In addition to this shape anisotropy, there is some uniaxial anisotropy. No magnetic dead layers have been observed. The magnetic moments within the Fe layers vary little with the distance from the interfaces. At the interfaces the Fe moment is reduced and an antiparallel moment is induced on the vanadium atoms. It is observed that ultrathin Fe layers behave in a 2D fashion when isolated by sufficiently thick vanadium layers; however, on thinning the vanadium layers, a magnetic coupling between the Fe layers has been observed. We also studied the superconducting properties of V/Fe sandwiches and superlattices. In both cases, the Fe layer, a strong pair-breaker, suppresses the superconducting transition temperature consistent with the current knowledge of the magnetic proximity effect. For the sandwiches with thin (thick) vanadium layers, the temperature dependence of the upper critical fields is consistent with the simple theory for a 2D (3D) superconductor. For the superlattices, when the vanadium layer is on the order of the BCS coherence length and the Fe layer is only a few atomic planes thick, a 2D-3D crossover has been observed in the temperature dependence of the

  3. Research to Conduct an Exploratory Experimental and Analytical Investigation of Alloys

    DTIC Science & Technology

    1980-11-01

    Properties of Forged and Heat 31 Treated Alpha-Two Titanium Aluminide Alloys 10 Effect of Interstitial Elements on Room 33 Temperature Notched (Kt-3.9...percent (three to five percent of engine weight) would be achieved with widespread application of the titanium aluminides in rotating hardwarei...vanadium substitution effect was also undertaken. One of the inconsistencies in the previous titanium aluminide investigations has been the poorer

  4. Atom probe study of vanadium interphase precipitates and randomly distributed vanadium precipitates in ferrite.

    PubMed

    Nöhrer, M; Zamberger, S; Primig, S; Leitner, H

    2013-01-01

    Atom probe tomography and transmission electron microscopy were used to examine the precipitation reaction in the austenite and ferrite phases in vanadium micro-alloyed steel after a thermo-mechanical process. It was observed that only in the ferrite phase precipitates could be found, whereupon two different types were detected. Thus, the aim was to reveal the difference between these two types. The first type was randomly distributed precipitates from V supersaturated ferrite and the second type V interphase precipitates. Not only the arrangement of the particles was different also the chemical composition. The randomly distributed precipitates consisted of V, C and N in contrast to that the interphase precipitates showed a composition of V, C and Mn. Furthermore the randomly distributed precipitates had maximum size of 20 nm and the interphase precipitates a maximum size of 15 nm. It was assumed that the reason for these differences is caused by the site in which they were formed. The randomly distributed precipitates were formed in a matrix consisting mainly of 0.05 at% C, 0.68 at% Si, 0.03 at% N, 0.145 at% V and 1.51 at% Mn. The interphase precipitates were formed in a region with a much higher C, Mn and V content. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Design, Synthesis and Pharmacological Evaluation of Novel Vanadium-Containing Complexes as Antidiabetic Agents

    PubMed Central

    Fedorova, Elena V.; Buryakina, Anna V.; Zakharov, Alexey V.; Filimonov, Dmitry A.; Lagunin, Alexey A.; Poroikov, Vladimir V.

    2014-01-01

    Based on the data about structure and antidiabetic activity of twenty seven vanadium and zinc coordination complexes collected from literature we developed QSAR models using the GUSAR program. These QSAR models were applied to 10 novel vanadium coordination complexes designed in silico in order to predict their hypoglycemic action. The five most promising substances with predicted potent hypoglycemic action were selected for chemical synthesis and pharmacological evaluation. The selected coordination vanadium complexes were synthesized and tested in vitro and in vivo for their hypoglycemic activities and acute rat toxicity. Estimation of acute rat toxicity of these five vanadium complexes was performed using a freely available web-resource (http://way2drug.com/GUSAR/acutoxpredict.html). It has shown that the selected compounds belong to the class of moderate toxic pharmaceutical agents, according to the scale of Hodge and Sterner. Comparison with the predicted data has demonstrated a reasonable correspondence between the experimental and predicted values of hypoglycemic activity and toxicity. Bis{tert-butyl[amino(imino)methyl]carbamato}oxovanadium (IV) and sodium(2,2′-Bipyridyl)oxo-diperoxovanadate(V) octahydrate were identified as the most potent hypoglycemic agents among the synthesized compounds. PMID:25057899

  6. Catalytic determination of vanadium in water

    USGS Publications Warehouse

    Fishman, M. J.; Skougstad, M.W.

    1964-01-01

    A rapid, accurate, and sensitive spectrophotometric method for the quantitative determination of trace amounts of vanadium in water is based on the catalytic effect of vanadium on the rate of oxidation of gallic acid by persulfate in acid solution. Under given conditions of concentrations of reactants, temperature, and reaction time, the extent of oxidation of gallic acid is proportional to the concentration of vanadium present. Vanadium is determined by measuring the absorbance of the sample at 415 m?? and comparison with standard solutions treated in an identical manner. Concentrations in the range of from 0.1 to 8.0 ??g. per liter may be determined with a standard deviation of 0.2 or less. By reducing the reaction time, the method may be extended to cover the range from 1 to 100 ??g. with a standard deviation of 0.8 or less. Several substances interfere, including chloride above 100 p.p.m., and bromide and iodide in much lower concentrations. Interference from the halides is eliminated or minimized by the addition of mercuric nitrate solution. Most other substances do not interfere at the concentration levels at which they commonly occur in natural waters.

  7. On the atomic structure of liquid Ni-Si alloys: a neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Gruner, S.; Marczinke, J.; Hennet, L.; Hoyer, W.; Cuello, G. J.

    2009-09-01

    The atomic structure of the liquid NiSi and NiSi2 alloys is investigated by means of neutron diffraction experiments with isotopic substitution. From experimental data-sets obtained using four Ni isotopes, partial structure factors and pair correlation functions are obtained by applying a reverse Monte Carlo modelling approach. Both alloys were found to exhibit a strong tendency to hetero-coordination within the first coordination shell. In particular, covalent Si-Si bonds with somewhat greater distances seem to influence the structure of the liquid NiSi alloy.

  8. On the atomic structure of liquid Ni-Si alloys: a neutron diffraction study.

    PubMed

    Gruner, S; Marczinke, J; Hennet, L; Hoyer, W; Cuello, G J

    2009-09-23

    The atomic structure of the liquid NiSi and NiSi(2) alloys is investigated by means of neutron diffraction experiments with isotopic substitution. From experimental data-sets obtained using four Ni isotopes, partial structure factors and pair correlation functions are obtained by applying a reverse Monte Carlo modelling approach. Both alloys were found to exhibit a strong tendency to hetero-coordination within the first coordination shell. In particular, covalent Si-Si bonds with somewhat greater distances seem to influence the structure of the liquid NiSi alloy.

  9. High strength nickel-chromium-iron austenitic alloy

    DOEpatents

    Gibson, Robert C.; Korenko, Michael K.

    1980-01-01

    A solid solution strengthened Ni-Cr-Fe alloy capable of retaining its strength at high temperatures and consisting essentially of 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminum, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06 zirconium, and the balance iron. After solution annealing at 1038.degree. C. for one hour, the alloy, when heated to a temperature of 650.degree. C., has a 2% yield strength of 307 MPa, an ultimate tensile strength of 513 MPa and a rupture strength of as high as 400 MPa after 100 hours.

  10. Tungsten - Yttrium Based Nuclear Structural Materials

    NASA Astrophysics Data System (ADS)

    Ramana, Chintalapalle; Chessa, Jack; Martinenz, Gustavo

    2013-04-01

    The challenging problem currently facing the nuclear science community in this 21st century is design and development of novel structural materials, which will have an impact on the next-generation nuclear reactors. The materials available at present include reduced activation ferritic/martensitic steels, dispersion strengthened reduced activation ferritic steels, and vanadium- or tungsten-based alloys. These materials exhibit one or more specific problems, which are either intrinsic or caused by reactors. This work is focussed towards tungsten-yttrium (W-Y) based alloys and oxide ceramics, which can be utilized in nuclear applications. The goal is to derive a fundamental scientific understanding of W-Y-based materials. In collaboration with University of Califonia -- Davis, the project is designated to demonstrate the W-Y based alloys, ceramics and composites with enhanced physical, mechanical, thermo-chemical properties and higher radiation resistance. Efforts are focussed on understanding the microstructure, manipulating materials behavior under charged-particle and neutron irradiation, and create a knowledge database of defects, elemental diffusion/segregation, and defect trapping along grain boundaries and interfaces. Preliminary results will be discussed.

  11. Structural and magnetic studies of half-metallic Heusler alloy Cr2CoSi nanoparticle synthesized by mechanical-alloying method

    NASA Astrophysics Data System (ADS)

    Saravanan, G.; Asvini, V.; Kalaiezhily, R. K.; Ravichandran, K.

    2018-05-01

    Heusler Alloy based Cr2CoSi nanoparticles were synthesized by using ball milling. X-ray diffractions studies were used to characterize the crystal structure of Cr2CoSi nanoparticles and magnetic properties were studied using VSM. XRD data analysis confirms the Heusler alloy phase showing the L21 structure. Magnetic properties are measured for synthesized samples having coercivity Hc = 389 Oe, with high saturation magnetization value Ms = 8.64 emu/g and remenance value Mr = 2.93 emu/g. Synthesized Heusler alloy Cr2CoSi nanoparticles can be potential materials for use in Spin polarized based spin sensors, spin devices, magnetic sensors and transducer applications.

  12. Formation of the structure of thin-sheet rolled product from a high-strength sparingly alloyed aluminum alloy ``nikalin''

    NASA Astrophysics Data System (ADS)

    Shurkin, P. K.; Belov, N. A.; Akopyan, T. K.; Alabin, A. N.; Aleshchenko, A. S.; Avxentieva, N. N.

    2017-09-01

    The regime of thermomechanical treatment of flat ingots of a high-strength sparingly alloyed alloy based on the Al-Zn-Mg-Ni-Fe system upon the production of thin-sheet rolled products with a reduction of more than 97% has been substantiated. Using experimental and calculated methods, the structure and phase composition of the experimental alloy in the as cast and deformed state and after heat treatment including quenching with subsequent aging have been studied. It has been found that the structure of the wrought semi-finished products after aging according to T and T1 regimes consists of the precipitation-hardened aluminum matrix and uniformly distributed isolated particles of Al9FeNi with a size of 1-2 μm, which provides a combination of high strength and satisfactory plasticity at the level of standard high-strength aluminum alloys of the Al-Zn-Mg-Cu system. The fractographic analysis confirmed that the tested samples underwent a ductile fracture.

  13. Criticality of iron and its principal alloying elements.

    PubMed

    Nuss, Philip; Harper, E M; Nassar, N T; Reck, Barbara K; Graedel, T E

    2014-04-01

    Because modern technology depends on reliable supplies of a wide variety of materials and because of increasing concern about those supplies, a comprehensive methodology was created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to iron and several of its main alloying elements (i.e., vanadium, chromium, manganese, and niobium). These elements represent the basic metals of any industrial society and are vital for national security and economic well-being. Assessments relating to the dimensions of criticality - supply risk, vulnerability to supply restriction, and environmental implications - for 2008 are made on the global level and for the United States. Evaluations of each of the multiple indicators are presented, with aggregate results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates. Iron has the lowest supply risk, primarily because of its widespread geological occurrence. Vanadium displays the highest cradle-to-gate environmental implications, followed by niobium, chromium, manganese, and iron. Chromium and manganese, both essential in steel making, display the highest vulnerability to supply restriction, largely because substitution or substitution at equal performance is not possible for all end-uses. From a comprehensive perspective, we regard the overall criticality as low for iron and modest for the alloying elements we evaluated.

  14. Essentiality and toxicity of vanadium supplements in health and pathology.

    PubMed

    Gruzewska, K; Michno, A; Pawelczyk, T; Bielarczyk, H

    2014-10-01

    The biological properties of vanadium complexes have become an object of interest due to their therapeutic potential in several diseases. However, the mechanisms of action of vanadium salts are still poorly understood. Vanadium complexes are cofactors for several enzymes and also exhibit insulin-mimetic properties. Thus, they are involved in the regulation of glucose metabolism, including in patients with diabetes. In addition, vanadium salts may also normalize blood pressure and play a key role in the metabolism of the thyroid and of iron as well as in the regulation of total cholesterol, cholesterol HDL and triglyceride (TG) levels in blood. Moreover, in cases of hypoxia, vanadium compounds may improve cardiomyocytes function. They may also exhibit both carcinogenic and anti-cancer properties. These include dose- and exposure-time-dependent induction and inhibition of the proliferation and survival of cancer cells. On the other hand, the balance between vanadium's therapeutic properties and its side effects has not yet been determined. Therefore, any studies on the potential use of vanadium compounds as supplements to support the treatment of a number of diseases must be strictly monitored for adverse effects.

  15. Effect of Iron and Magnesium on Alloy AL9M Structure and Properties

    NASA Astrophysics Data System (ADS)

    Bazhenov, V. E.; Koltygin, A. V.; Belov, V. D.

    2017-09-01

    The effect of iron impurity on the structure and properties of aluminum alloy AL9M, especially its action on magnesium distribution within the structure, is studied. The microstructure of a cast component of this alloy broken during operation is analyzed. It is shown that iron impurity has an unfavorable effect on structure and mechanical properties of a casting due to appearance of Al9Fe2Si and Al18Fe2Mg7Si10 intermetallics. Formation of these intermetallics consumes a considerable amount of magnesium and lowers the content of the Q(Al5Cu2Mg8Si6) strengthening phase in the alloy structure.

  16. Spectrophotometric determination of vanadium in rutile and in mafic igneous rocks

    USGS Publications Warehouse

    Marinenko, John; Mei, Leung

    1974-01-01

    Minor and major levels of vanadium in rutile are separated from titanium and iron by sample fusion with sodium carbonate followed by water leach and filtration. The filtrate is then acidified with hydrochloric acid. Silicates are decomposed with a mixture of hydrofluoric and hydrochloric acids, and iron is separated by extraction of its chloride with diethyl ether. Sample vanadium in hydrochloric acid is then quantitatively reduced to vanadium(IV) with sulfurous acid. The remaining sulfur dioxide is expelled by heating. Vanadium (IV) then is reacted with excess of iron(III) at reduced acidity (pH 5) in the presence of 1,10-phenanthroline to yield the orange-red iron(II) 1,10-phenanthroline complex. Iron(II) generated by vanadium(IV) is a measure of total vanadium in the sample. The proposed method is free from elemental interferences because the color development cannot take place without the two redox reactions described above, and these are, under the outlined experimental conditions, quantitative only for vanadium.

  17. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1991-01-01

    The general objective of the Light Aerospace Alloy and Structures Technology (LA2ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and associated thermal gradient structures in close collaboration with Langley researchers. Specific technical objectives are established for each research project. Relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanic analyses, measurement advances, and a pool of educated graduate students are sought.

  18. Structure of tetragonal martensite in the In95.42Cd4.58 cast alloy

    NASA Astrophysics Data System (ADS)

    Khlebnikova, Yu. V.; Egorova, L. Yu.; Rodionov, D. P.; Kazantsev, V. A.

    2017-11-01

    The structure of martensite in the In95.42Cd4.58 alloy has been studied by metallography, X-ray diffraction, dilatometry, and transmission electron microscopy. It has been shown that a massive structure built of colonies of tetragonal lamellar plates divided by a twin boundary {101}FCT is formed in the alloy under cooling below the martensite FCC → FCT transition temperature. The alloy recrystallizes after a cycle of FCT → FCC → FCT transitions with a decrease in the grain size by several times compared with the initial structure such fashion that the size of massifs and individual martensite lamella in the massif correlates with the change in the size of the alloy grain. Using thermal cycling, it has been revealed that the alloy tends to stabilize the high-temperature phase.

  19. Rapid Repairs: Surface Preparation of Ti-3 Al-2.5V Alloy Tubes by Fiber Laser and Welding

    DTIC Science & Technology

    2008-11-01

    processing of titanium 6Al - 4V alloy for potential aerospace component cleaning application, Appl Surf Sci 2005;247:623-630. [11] Turner MW, Crouse...Debroy T, Heat transfer and fluid flow during keyhole mode laser welding of tantalum, Ti- 6Al - 4V , 304 Stainless Steel and Vanadium, J Phy D : Appl Phy...14Titanium alloys are used extensively in aerospace applications mainly due to their superior strength to weight ratio. Different grades of titanium

  20. In situ formation of heterobimetallic salen complexes containing titanium and/or vanadium ions.

    PubMed

    Belokon, Yuri N; Harrington, Ross W; North, Michael; Young, Carl

    2008-05-05

    A combination of high-resolution electrospray mass spectrometry and (1)H NMR spectroscopy has been used to prove that when a mixture of [(salen)TiO]2 complexes containing two different salen ligands (salen and salen') is formed, an equilibrium is established between the homodimers and the heterodimer [(salen)TiO2Ti(salen')]. Depending upon the structure and stereochemistry of the two salen ligands, the equilibrium may favor either the homodimers or the heterodimer. Extension of this process to mixtures of titanium(salen) complexes [(salen)TiO]2 and vanadium (V)(salen') complexes [(salen')VO] (+)Cl (-) allowed the in situ formation of the heterobimetallic complex [(salen)TiO2V(salen')] (+)X (-) to be confirmed for all combinations of salen ligands studied except when the salen ligand attached to titanium contained highly electron-withdrawing nitro-groups. The rate of equilibration between heterobimetallic complexes is faster than that between two titanium complexes as determined by line broadening in the (1)H NMR spectra. These structural results explain the strong rate-inhibiting effect of vanadium (V)(salen) complexes in asymmetric cyanohydrin synthesis catalyzed by [(salen)TiO]2 complexes. It has also been demonstrated for the first time that the titanium and vanadium complexes can undergo exchange of salen ligands and that this is catalyzed by protic solvents. However, the ligand exchange is relatively slow (occurring on a time scale of days at room temperature) and so does not complicate studies aimed at using heterobimetallic titanium and vanadium salen complexes as asymmetric catalysts. Attempts to obtain a crystal structure of a heterobimetallic salen complex led instead to the isolation of a trinuclear titanium(salen) complex, the formation of which is also consistent with the catalytic results obtained previously.

  1. Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

    USGS Publications Warehouse

    Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

    1990-01-01

    The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

  2. Influence of Heat Treatment Conditions on the Properties of Vanadium Oxide Thin Films for Thermochromic Applications.

    PubMed

    Kim, Donguk; Kwon, Samyoung; Park, Young; Boo, Jin-Hyo; Nam, Sang-Hun; Joo, Yang Tae; Kim, Minha; Lee, Jaehyeong

    2016-05-01

    In present work, the effects of the heat treatment on the structural, optical, and thermochromic properties of vanadium oxide films were investigated. Vanadium dioxide (VO2) thin films were deposited on glass substrate by reactive pulsed DC magnetron sputtering from a vanadium metal target in mixture atmosphere of argon and oxygen gas. Various heat treatment conditions were applied in order to evaluate their influence on the crystal phases formed, surface morphology, and optical properties. The films were characterized by an X-ray diffraction (XRD) in order to investigate the crystal structure and identify the phase change as post-annealing temperature of 500-600 degrees C for 5 minutes. Surface conditions of the obtained VO2(M) films were analyzed by field emission scanning electron microscopy (FE-SEM) and the semiconductor-metal transition (SMT) characteristics of the VO2 films were evaluate by optical spectrophotometry in the UV-VIS-NIR, controlling temperature of the films.

  3. NREL, American Vanadium Demonstrate First-of-Its-Kind Battery Management

    Science.gov Websites

    System | Energy Systems Integration Facility | NREL American Vanadium NREL, American Vanadium Demonstrate First-of-Its-Kind Battery Management System NREL researchers are collaborating with American Vanadium, an integrated energy storage company, to evaluate and demonstrate the first North American

  4. Mo-Si-B alloys for ultrahigh-temperature structural applications.

    PubMed

    Lemberg, J A; Ritchie, R O

    2012-07-10

    A continuing quest in science is the development of materials capable of operating structurally at ever-increasing temperatures. Indeed, the development of gas-turbine engines for aircraft/aerospace, which has had a seminal impact on our ability to travel, has been controlled by the availability of materials capable of withstanding the higher-temperature hostile environments encountered in these engines. Nickel-base superalloys, particularly as single crystals, represent a crowning achievement here as they can operate in the combustors at ~1100 °C, with hot spots of ~1200 °C. As this represents ~90% of their melting temperature, if higher-temperature engines are ever to be a reality, alternative materials must be utilized. One such class of materials is Mo-Si-B alloys; they have higher density but could operate several hundred degrees hotter. Here we describe the processing and structure versus mechanical properties of Mo-Si-B alloys and further document ways to optimize their nano/microstructures to achieve an appropriate balance of properties to realistically compete with Ni-alloys for elevated-temperature structural applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Impact of vanadium ions in barium borate glass

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.; Hammad, Ahmed H.

    2015-02-01

    Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data.

  6. Impact of vanadium ions in barium borate glass.

    PubMed

    Abdelghany, A M; Hammad, Ahmed H

    2015-02-25

    Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. The Syntheses and Structure of the First Vanadium(IV) and Vanadium(V) Binary Azides, V(N3)4, [V(N3)6]2- and [V(N3)6]- (Preprint)

    DTIC Science & Technology

    2009-11-17

    V(N3)3(N3S2)] 2- , [22] have been reported, and no binary vanadium(V) compounds had been known except for VF5, VF6 - and V2O5 . By analogy with...valves. Volatile materials were handled in a Pyrex glass or stainless steel/Teflon-FEP vacuum line. [31] All reaction vessels were passivated with ClF3...successful synthesis of the [V(N3)6] - anion, the only binary vanadium(V) compound known besides VF5, VF6 - and V2O5 . N1’ N8 N9 N1 N2 N3 V N4 N5 N6 N2

  8. Modified lithium vanadium oxide electrode materials products and methods

    DOEpatents

    Thackeray, Michael M.; Kahaian, Arthur J.; Visser, Donald R.; Dees, Dennis W.; Benedek, Roy

    1999-12-21

    A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV.sub.3 O.sub.8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.

  9. Effect of the carbide phase on the tribological properties of high-manganese antiferromagnetic austenitic steels alloyed with vanadium and molybdenum

    NASA Astrophysics Data System (ADS)

    Korshunov, L. G.; Kositsina, I. I.; Sagaradze, V. V.; Chernenko, N. L.

    2011-07-01

    Effect of special carbides (VC, M 6C, Mo2C) on the wear resistance and friction coefficient of austenitic stable ( M s below -196°C) antiferromagnetic ( T N = 40-60°C) steels 80G20F2, 80G20M2, and 80G20F2M2 has been studied. The structure and the effective strength (microhardness H surf, shear resistance τ) of the surface layer of these steels have been studied using optical and electron microscopy. It has been shown that the presence of coarse particles of primary special carbides in the steels 80G20F2, 80G20M2, and 80G20F2M2 quenched from 1150°C decreases the effective strength and the resistance to adhesive and abrasive wear of these materials. This is caused by the negative effect of carbide particles on the toughness of steels and by a decrease in the carbon content in austenite due to a partial binding of carbon into the above-mentioned carbides. The aging of quenched steels under conditions providing the maximum hardness (650°C for 10 h) exerts a substantial positive effect on the parameters of the effective strength ( H surf, τ) of the surface layer and, correspondingly, on the resistance of steels to various types of wear (abrasive, adhesive, and caused by the boundary friction). The maximum positive effect of aging on the wear resistance is observed upon adhesive wear of the steels under consideration. Upon friction with enhanced sliding velocities (to 4 m/s) under conditions of intense (to 500-600°C) friction-induced heating, the 80G20F2, 80G20M2, and, especially, 80G20F2M2 steels subjected to quenching and aging substantially exceed the 110G13 (Hadfield) steel in their tribological properties. This is due to the presence in these steels of a favorable combination of high effective strength and friction heat resistance of the surface layer, which result from the presence of a large amount of special carbides in these steels and from a high degree of alloying of the matrix of these steels by vanadium and molybdenum. In the process of friction

  10. Hydrothermal Synthesis of Nanostructured Vanadium Oxides

    PubMed Central

    Livage, Jacques

    2010-01-01

    A wide range of vanadium oxides have been obtained via the hydrothermal treatment of aqueous V(V) solutions. They exhibit a large variety of nanostructures ranging from molecular clusters to 1D and 2D layered compounds. Nanotubes are obtained via a self-rolling process while amazing morphologies such as nano-spheres, nano-flowers and even nano-urchins are formed via the self-assembling of nano-particles. This paper provides some correlation between the molecular structure of precursors in the solution and the nanostructure of the solid phases obtained by hydrothermal treatment. PMID:28883325

  11. Strength properties and structure of a submicrocrystalline Al-Mg-Mn alloy under shock compression

    NASA Astrophysics Data System (ADS)

    Petrova, A. N.; Brodova, I. G.; Razorenov, S. V.

    2017-06-01

    The results of studying the strength of a submicrocrystalline aluminum A5083 alloy (chemical composition was 4.4Mg-0.6Mn-0.11Si-0.23Fe-0.03Cr-0.02Cu-0.06Ti wt % and Al base) under shockwave compression are presented. The submicrocrystalline structure of the alloy was produced in the process of dynamic channel-angular pressing at a strain rate of 104 s-1. The average size of crystallites in the alloy was 180-460 nm. Hugoniot elastic limit σHEL, dynamic yield stress σy, and the spall strength σSP of the submicrocrystalline alloy were determined based on the free-surface velocity profiles of samples during shock compression. It has been established that upon shock compression, the σHEL and σy of the submicrocrystalline alloy are higher than those of the coarse-grained alloy and σsp does not depend on the grain size. The maximum value of σHEL reached for the submicrocrystalline alloy is 0.66 GPa, which is greater than that in the coarse-crystalline alloy by 78%. The dynamic yield stress is σy = 0.31 GPa, which is higher than that of the coarse-crystalline alloy by 63%. The spall strength is σsp = 1.49 GPa. The evolution of the submicrocrystalline structure of the alloy during shock compression was studied. It has been established that a mixed nonequilibrium grain-subgrain structure with a fragment size of about 400 nm is retained after shock compression, and the dislocation density and the hardness of the alloy are increased.

  12. Low Young's modulus Ti-based porous bulk glassy alloy without cytotoxic elements.

    PubMed

    Nicoara, M; Raduta, A; Parthiban, R; Locovei, C; Eckert, J; Stoica, M

    2016-05-01

    A new a biocompatible Ti42Zr40Ta3Si15 (atomic %) porous bulk glassy alloy was produced by combination of rapid solidification and powder metallurgy techniques. Amorphous alloy ribbons were fabricated by melt spinning, i.e. extremely fast quenching the molten alloy with 10(6)K/s from T=1973K down to room temperature. The ribbons were then cryo-milled at liquid nitrogen temperature in order to produce powder, which was subsequently hot pressed. The resulting thick pellets have a porosity of about 14vol%, a high compression strength of 337MPa and a Young's modulus of about E=52GPa, values very close to those characteristic of cortical bone. Moreover, the morphology of the samples is very similar to that of cortical bone. The biocompatibility, which is due to the absence of any toxic element in the chemical composition, together with the suitable mechanical behavior, make these samples promising for orthopedic and dentistry applications. Ti-based alloys are nowadays the standard solution for biomedical implants. However, both the conventional crystalline and amorphous alloys have higher rigidity as the human bone, leading to the damage of the bone at the interface, and contains harmful elements like vanadium, aluminum, nickel or beryllium. The hierarchical porous structures based on glassy alloys with biocompatible elements is a much better alternative. This work presents for the first time the manufacturing of such porous bodies starting from Ti-based amorphous alloy ribbons, which contains only non-harmful elements. The morphology and the compressive mechanical properties of these new products are analyzed in regard with those characteristic to the cortical bone. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Structure and thermomechanical behavior of NiTiPt shape memory alloy wires.

    PubMed

    Lin, Brian; Gall, Ken; Maier, Hans J; Waldron, Robbie

    2009-01-01

    The objective of this work is to understand the structure-property relationships in polycrystalline NiTiPt (Ti 42.7 at.% Ni 7.5 at %Pt) with a composition showing pseudoelasticity at ambient temperatures. Structural characterization of the alloy includes grain size determination and texture analysis while the thermomechanical properties are explored using tensile testing. Variation in heat treatment is used as a vehicle to modify microstructure. The results are compared to experiments on Ni-rich NiTi alloy wires (Ti-51.0 at.% Ni), which are in commercial use in various biomedical applications. With regards to microstructure, both alloys exhibit a <111> fiber texture along the wire drawing axis; however, the NiTiPt alloy grain size is smaller than that of the Ni-rich NiTi wires, while the latter materials contain second-phase precipitates. Given the nanometer-scale grain size in NiTiPt and the dispersed, nanometer-scale precipitate size in NiTi, the overall strength and ductility of the alloys are essentially identical when given appropriate heat treatments. Property differences include a much smaller stress hysteresis and smaller temperature dependence of the transformation stress for NiTiPt alloys compared to NiTi alloys. Potential benefits and implications for use in vascular stent applications are discussed.

  14. Improved Electroformed Structural Copper and Copper Alloys

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Hudson, W.; Babcock, B.; Edwards, R.

    1998-01-01

    Electroforming offers a superior means for fabricating internally cooled heat exchangers and structures subjected to thermal environments. Copper is deposited from many such applications because of the good thermal conductivity. It suffers from mediocre yield strength as a structural material and loses mechanical strength at intermediate temperatures. Mechanical properties similar to those of electroformed nickel are desired. Phase 1 examined innovative means to improve deposited copper structural performance. Yield strengths as high as 483 MPa (70 ksi) were obtained with useful ductility while retaining a high level of purity essential to good thermal conductivity. Phase 2 represents a program to explore new additive combinations in copper electrolytes to produce a more fine, equiaxed grain which can be thermally stabilized by other techniques such as alloying in modest degrees and dispersion strengthening. Evaluation of new technology - such as the codeposition of fullerness (diamond-like) particles were made to enhance thermal conductivity in low alloys. A test fire quality tube-bundle engine was fabricated using these copper property improvement concepts to show the superiority of the new coppers and fabrications methods over competitive technologies such as brazing and plasma deposition.

  15. A novel process for comprehensive utilization of vanadium slag

    NASA Astrophysics Data System (ADS)

    Liu, Li-ying; Du, Tao; Tan, Wen-jun; Zhang, Xin-pu; Yang, Fan

    2016-02-01

    Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V2O5/TiO2 system were synthesized. The structural properties of the as-synthesized zeolite A and the V2O5/TiO2 system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.

  16. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Astrophysics Data System (ADS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-06-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  17. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Technical Reports Server (NTRS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-01-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  18. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    NASA Astrophysics Data System (ADS)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27-61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72-93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  19. A new electrocatalyst and its application method for vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Wei, Guanjie; Jing, Minghua; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei

    2015-08-01

    The edge plane in carbon structure has good electrocatalytic activity toward vanadium redox reaction. To apply it in vanadium redox flow battery (VRFB) practically, the graphite nanopowders (GNPs) containing amounts of edge planes are used as electrocatalyst and embedded in the electrospun carbon nanofibers (ECNFs) by different mass ratios to make composite electrodes. The morphology and electrochemical activity of the GNPs and the composite electrodes containing them are characterized. Compared with the pristine ECNFs, the composite electrodes show much higher electrochemical activity. With the increase of GNPs content in composite electrodes, the electrochemical reversibility of the vanadium redox couples also increases. It proves the addition of GNPs can surely improve the electrochemical activity of ECNFs. Among the composite electrodes, the ECNFs containing 30 nm GNP by mass ratio of 1:50 show the best electrochemical activity, largest active surface area and excellent stability. Due to the high performance of GNP/ECNFs composite electrode and its relatively low cost preparation process, the GNPs are expected to be used as electrocatalyst in VRFB on a large scale to improve the cell performance.

  20. 40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the vanadium ore...

  1. 40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the vanadium ore...

  2. Quantitation and detection of vanadium in biologic and pollution materials

    NASA Technical Reports Server (NTRS)

    Gordon, W. A.

    1974-01-01

    A review is presented of special considerations and methodology for determining vanadium in biological and air pollution materials. In addition to descriptions of specific analysis procedures, general sections are included on quantitation of analysis procedures, sample preparation, blanks, and methods of detection of vanadium. Most of the information presented is applicable to the determination of other trace elements in addition to vanadium.

  3. High strength ferritic alloy

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

  4. Structural characterization of vanadium oxide catalysts supported on nanostructured silica SBA-15 using X-ray absorption spectroscopy

    PubMed Central

    2010-01-01

    The local structure of vanadium oxide supported on nanostructured SiO2 (VxOy/SBA-15) was investigated by in situ X-ray absorption spectroscopy (XAS). Because the number of potential parameters in XAS data analysis often exceeds the number of "independent" parameters, evaluating the reliability and significance of a particular fitting procedure is mandatory. The number of independent parameters (Nyquist) may not be sufficient. Hence, in addition to the number of independent parameters, a novel approach to evaluate the significance of structural fitting parameters in XAS data analysis is introduced. Three samples with different V loadings (i.e. 2.7 wt %, 5.4 wt %, and 10.8 wt %) were employed. Thermal treatment in air at 623 K resulted in characteristic structural changes of the V oxide species. Independent of the V loading, the local structure around V centers in dehydrated VxOy/SBA-15 corresponded to an ordered arrangement of adjacent V2O7 units. Moreover, the V2O7 units were found to persist under selective oxidation reaction conditions. PMID:20181222

  5. Structural characterization of vanadium oxide catalysts supported on nanostructured silica SBA-15 using X-ray absorption spectroscopy.

    PubMed

    Walter, Anke; Herbert, Rita; Hess, Christian; Ressler, Thorsten

    2010-02-11

    The local structure of vanadium oxide supported on nanostructured SiO2 (VxOy/SBA-15) was investigated by in situ X-ray absorption spectroscopy (XAS). Because the number of potential parameters in XAS data analysis often exceeds the number of "independent" parameters, evaluating the reliability and significance of a particular fitting procedure is mandatory. The number of independent parameters (Nyquist) may not be sufficient. Hence, in addition to the number of independent parameters, a novel approach to evaluate the significance of structural fitting parameters in XAS data analysis is introduced. Three samples with different V loadings (i.e. 2.7 wt %, 5.4 wt %, and 10.8 wt %) were employed. Thermal treatment in air at 623 K resulted in characteristic structural changes of the V oxide species. Independent of the V loading, the local structure around V centers in dehydrated VxOy/SBA-15 corresponded to an ordered arrangement of adjacent V2O7 units. Moreover, the V2O7 units were found to persist under selective oxidation reaction conditions.

  6. Ab initio investigation of competing antiferromagnetic structures in low Si-content FeMn(PSi) alloy

    NASA Astrophysics Data System (ADS)

    Li, Guijiang; Eriksson, Olle; Johansson, Börje; Vitos, Levente

    2016-06-01

    The antiferromagnetic structures of a low Si-content FeMn(PSi) alloy were investigated by first principles calculations. One possible antiferromagnetic structure in supercell along the c-axis was revealed in FeMnP0.75Si0.25 alloy. It was found that atomic disorder occupation between Fe atom on 3f and Mn atoms on 3g sites is responsible for the formation of antiferromagnetic structures. Furthermore the magnetic competition and the coupling between possible AFM supercells along the c and a-axis can promote a non-collinear antiferromagnetic structure. These theoretical investigations help to deeply understand the magnetic order in FeMn(PSi) alloys and benefit to explore the potential magnetocaloric materials in Fe2P-type alloys.

  7. Aluminum-Silicon Alloy Having Improved Properties at Elevated Temperatures and Articles Cast Therefrom

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2002-01-01

    An aluminum alloy suitable for high temperature applications, such as heavy duty pistons and other internal combustion applications. having the following composition, by weight percent (wt %): Silicon: 11.0-14.0; Copper: 5.6-8.0; Iron: 0-0.8; Magnesium: 0.5-1.5; Nickel: 0.05-0.9; Manganese: 0.5-1.5; Titanium: 0.05-1.2; Zirconium: 0.12-1.2; Vanadium: 0.05-1.2; Zinc: 0.005-0.9; Strontium: 0.001-0.1; Aluminum: balance. In this alloy the ratio of silicon:magnesium is 10-25, and the ratio of copper:magnesium is 4-15. After an article is cast from this alloy, the article is treated in a solutionizing step which dissolves unwanted precipitates and reduces any segregation present in the original alloy. After this solutionizing step, the article is quenched, and is then aged at an elevated temperature for maximum strength.

  8. Alloys for a liquid metal fast breeder reactor

    DOEpatents

    Rowcliffe, Arthur F.; Bleiberg, Melvin L.; Diamond, Sidney; Bajaj, Ram

    1979-01-01

    An essentially gamma-prime precipitation-hardened iron-chromium-nickel alloy has been designed with emphasis on minimum nickel and chromium contents to reduce the swelling tendencies of these alloys when used in liquid metal fast breeder reactors. The precipitation-hardening components have been designed for phase stability and such residual elements as silicon and boron, also have been selected to minimize swelling. Using the properties of these alloys in one design would result in an increased breeding ratio over 20% cold worked stainless steel, a reference material, of 1.239 to 1.310 and a reduced doubling time from 15.8 to 11.4 years. The gross stoichiometry of the alloying composition comprises from about 0.04% to about 0.06% carbon, from about 0.05% to about 1.0% silicon, up to about 0.1% zirconium, up to about 0.5% vanadium, from about 24% to about 31% nickel, from 8% to about 11% chromium, from about 1.7% to about 3.5% titanium, from about 1.0% to about 1.8% aluminum, from about 0.9% to about 3.7% molybdenum, from about 0.04% to about 0.8% boron, and the balance iron with incidental impurities.

  9. Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

    PubMed

    Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

    2015-10-01

    Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A Kinetics and Equilibrium Study of Vanadium Dissolution from Vanadium Oxides and Phosphates in Battery Electrolytes: Possible Impacts on ICD Battery Performance.

    PubMed

    Bock, David C; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2013-06-01

    Silver vanadium oxide (Ag 2 V 4 O 11 , SVO) has enjoyed widespread commercial success over the past 30 years as a cathode material for implantable cardiac defibrillator (ICD) batteries. Recently, silver vanadium phosphorous oxide (Ag 2 VO 2 PO 4 , SVPO) has been studied as possibly combining the desirable thermal stability aspects of LiFePO 4 with the electrical conductivity of SVO. Further, due to the noted insoluble nature of most phosphate salts, a lower material solubility of SVPO relative to SVO is anticipated. Thus, the first vanadium dissolution studies of SVPO in battery electrolyte solutions are described herein. The equilibrium solubility of SVPO was ~5 times less than SVO, with a rate constant of dissolution ~3.5 times less than that of SVO. The vanadium dissolution in SVO and SVPO can be adequately described with a diffusion layer model, as supported by the Noyes-Whitney equation. Cells prepared with vanadium-treated anodes displayed higher AC impedance and DC resistance relative to control anodes. These data support the premise that SVPO cells are likely to exhibit reduced cathode solubility and thus less affected by increased cell resistance due to cathode solubility compared to SVO based cells.

  11. Tackling capacity fading in vanadium flow batteries with amphoteric membranes

    NASA Astrophysics Data System (ADS)

    Oldenburg, Fabio J.; Schmidt, Thomas J.; Gubler, Lorenz

    2017-11-01

    Capacity fading and poor electrolyte utilization caused by electrolyte imbalance effects are major drawbacks for the commercialization of vanadium flow batteries (VFB). The influence of membrane type (cationic, anionic, amphoteric) on these effects is studied by determining the excess and net flux of each vanadium ion in an operating VFB assembled with a cation exchange membrane (CEM), Nafion® NR212, an anion exchange membrane (AEM), Fumatech FAP-450, and an amphoteric ion exchange membrane (AIEM) synthesized in-house. It is shown that the net vanadium flux, accompanied by water transport, is directed towards the positive side for the CEM and towards the negative side for the AEM. The content of cation and anion exchange groups in the AIEM is adjusted via radiation grafting to balance the vanadium flux between the two electrolyte sides. With the AIEM the net vanadium flux is significantly reduced and capacity fading due to electrolyte imbalances can be largely eliminated. The membrane's influence on electrolyte imbalance effects is characterized and quantified in one single charge-discharge cycle by analyzing the content of the four different vanadium species in the two electrolytes. The experimental data recorded herewith conclusively explains the electrolyte composition after 80 cycles.

  12. Natural ageing responses of duplex structured Mg-Li based alloys

    PubMed Central

    Li, C. Q.; Xu, D. K.; Wang, B. J.; Sheng, L. Y.; Qiao, Y. X.; Han, E. H.

    2017-01-01

    Natural ageing responses of duplex structured Mg-6%Li and Mg-6%Li-6%Zn-1.2%Y alloys have been investigated. Microstructural analyses revealed that the precipitation and coarsening process of α-Mg particles could occur in β-Li phases of both two alloys during ageing process. Since a certain amount of Mg atoms in β-Li phases were consumed for the precipitation of abundant tiny MgLiZn particles, the size of α-Mg precipitates in Mg-6%Li-6%Zn-1.2%Y alloy was relatively smaller than that in Mg-6%Li alloy. Micro hardness measurements demonstrated that with the ageing time increasing, the α-Mg phases in Mg-6%Li alloy could have a constant hardness value of 41 HV, but the contained β-Li phases exhibited a slight age-softening response. Compared with the Mg-6%Li alloy, the age-softening response of β-Li phases in Mg-6%Li-6%Zn-1.2%Y alloy was much more profound. Meanwhile, a normal age-hardening response of α-Mg phases was maintained. Tensile results indicated that obvious ageing-softening phenomenon in terms of macro tensile strength occurred in both two alloys. Failure analysis demonstrated that for the Mg-6%Li alloy, cracks were preferentially initiated at α-Mg/β-Li interfaces. For the Mg-6%Li-6%Zn-1.2%Y alloy, cracks occurred at both α-Mg/β-Li interfaces and slip bands in α-Mg and β-Li phases. PMID:28053318

  13. Structure, mechanical properties, and grindability of dental Ti-Zr alloys.

    PubMed

    Ho, Wen-Fu; Chen, Wei-Kai; Wu, Shih-Ching; Hsu, Hsueh-Chuan

    2008-10-01

    Structure, mechanical properties and grindability of a series of binary Ti-Zr alloys with zirconium contents ranging from 10 to 40 wt% have been investigated. Commercially pure titanium (c.p. Ti) was used as a control. Experimental results indicated that the diffraction peaks of all the Ti-Zr alloys matched those for alpha Ti. No beta-phase peaks were found. The hardness of the Ti-Zr alloys increased as the Zr contents increased, and ranged from 266 HV (Ti-10Zr) to 350 HV (Ti-40Zr). As the concentration of zirconium in the alloys increased, the strength, elastic recovery angles and hardness increased. Moreover, the elastically recoverable angle of Ti-40Zr was higher than of c.p. Ti by as much as 550%. The grindability of each metal was found to be largely dependent on the grinding conditions. The Ti-40Zr alloy had a higher grinding rate and grinding ratio than c.p. Ti at low speed. The grinding rate of the Ti-40Zr alloy at 500 m/min was about 1.8 times larger than that of c.p. Ti, and the grinding ratio was about 1.6 times larger than that of c.p. Ti. Our research suggested that the Ti-40Zr alloy has better mechanical properties, excellent elastic recovery capability and improved grindability at low grinding speed. The Ti-40Zr alloy has a great potential for use as a dental machining alloy.

  14. Chemical conversion coating for protecting magnesium alloys from corrosion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh

    A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds asmore » self-healing moieties to defect sites, thus providing active corrosion protection.« less

  15. Defect-mediated room temperature ferromagnetism in vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Yang, Tsung-Han; Nori, Sudhakar; Zhou, Honghui; Narayan, Jagdish

    2009-09-01

    High quality epitaxial undoped vanadium oxide (VO2) thin films on c-plane sapphire (0001) substrate have been grown using pulsed laser deposition technique. The as-grown films exhibited excellent structural and transport properties without requiring further annealing treatments for these oxygen-deficient oxide films. The epitaxial growth has been achieved via domain matching epitaxy, where matching of integral multiples of planes occurs across the film-substrate interface. The magnetic properties of vanadium oxide (VO2) films investigated at different temperatures in the range of 10-360 K showed significant magnetic hysteresis as well as saturation of the magnetic moment. The origin of ferromagnetic properties with an estimated Curie temperature above 500 K is discussed in the absence of magnetic impurities in VO2 thin films as determined by x-ray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy.

  16. Uncoupling binding of substrate CO from turnover by vanadium nitrogenase.

    PubMed

    Lee, Chi Chung; Fay, Aaron W; Weng, Tsu-Chien; Krest, Courtney M; Hedman, Britt; Hodgson, Keith O; Hu, Yilin; Ribbe, Markus W

    2015-11-10

    Biocatalysis by nitrogenase, particularly the reduction of N2 and CO by this enzyme, has tremendous significance in environment- and energy-related areas. Elucidation of the detailed mechanism of nitrogenase has been hampered by the inability to trap substrates or intermediates in a well-defined state. Here, we report the capture of substrate CO on the resting-state vanadium-nitrogenase in a catalytically competent conformation. The close resemblance of this active CO-bound conformation to the recently described structure of CO-inhibited molybdenum-nitrogenase points to the mechanistic relevance of sulfur displacement to the activation of iron sites in the cofactor for CO binding. Moreover, the ability of vanadium-nitrogenase to bind substrate in the resting-state uncouples substrate binding from subsequent turnover, providing a platform for generation of defined intermediate(s) of both CO and N2 reduction.

  17. Environmental Control of Vanadium Haloperoxidases and Halocarbon Emissions in Macroalgae.

    PubMed

    Punitha, Thillai; Phang, Siew-Moi; Juan, Joon Ching; Beardall, John

    2018-04-24

    Vanadium-dependent haloperoxidases (V-HPO), able to catalyze the reaction of halide ions (Cl - , Br - , I - ) with hydrogen peroxide, have a great influence on the production of halocarbons, which in turn are involved in atmospheric ozone destruction and global warming. The production of these haloperoxidases in macroalgae is influenced by changes in the surrounding environment. The first reported vanadium bromoperoxidase was discovered 40 years ago in the brown alga Ascophyllum nodosum. Since that discovery, more studies have been conducted on the structure and mechanism of the enzyme, mainly focused on three types of V-HPO, the chloro- and bromoperoxidases and, more recently, the iodoperoxidase. Since aspects of environmental regulation of haloperoxidases are less well known, the present paper will focus on reviewing the factors which influence the production of these enzymes in macroalgae, particularly their interactions with reactive oxygen species (ROS).

  18. Hydrogen embrittlement of structural alloys. A technology survey

    NASA Technical Reports Server (NTRS)

    Carpenter, J. L., Jr.; Stuhrke, W. F.

    1976-01-01

    Technical abstracts for about 90 significant documents relating to hydrogen embrittlement of structural metals and alloys are reviewed. Particular note was taken of documents regarding hydrogen effects in rocket propulsion, aircraft propulsion and hydrogen energy systems, including storage and transfer systems.

  19. NASA-UVA light aerospace alloy and structures technology program (LA(sup 2)ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Haviland, John K.; Herakovich, Carl T.; Pilkey, Walter D.; Pindera, Marek-Jerzy; Scully, John R.; Starke, Edgar A., Jr.; Stoner, Glenn E.; Thornton, Earl A.; Wawner, Franklin E., Jr.

    1992-01-01

    The general objective of the Light Aerospace Alloy and Structures Technology (LA(sup 2)ST) Program is to conduct interdisciplinary graduate student research on the performance of next generation, light weight aerospace alloys, composites, and thermal gradient structures in collaboration with Langley researchers. Specific technical objectives are established for each research project. We aim to produce relevant data and basic understanding of material behavior and microstructure, new monolithic and composite alloys, advanced processing methods, new solid and fluid mechanics analyses, measurement advances, and critically, a pool of educated graduate students for aerospace technologies. Four research areas are being actively investigated, including: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals and Composites; (2) Aerospace Materials Science; (3) Mechanics of Materials and Composites for Aerospace Structures; and (4) Thermal Gradient Structures.

  20. Vanadium-uranium extraction from Wyoming vanadiferoud silicates. Report of investigations/1983

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hayashi, M.; Nichols, I.L.; Huiatt, J.L.

    1983-11-01

    The Bureau of Mines conducted laboratory studies on low-grade vanadiferous silicates from the Pumpkin Buttes and Nine Mile Lake deposits of Wyoming to examine techniques for extracting vanadium and uranium. Recovery from low-grade sources such as these could contribute to future vanadium production and reduce reliance on vanadium imports.

  1. Nuclear reactor fuel element with vanadium getter on cladding

    DOEpatents

    Johnson, Carl E.; Carroll, Kenneth G.

    1977-01-01

    A nuclear reactor fuel element is described which has an outer cladding, a central core of fissionable or mixed fissionable and fertile fuel material and a layer of vanadium as an oxygen getter on the inner surface of the cladding. The vanadium reacts with oxygen released by the fissionable material during irradiation of the core to prevent the oxygen from reacting with and corroding the cladding. Also described is a method for coating the inner surface of small diameter tubes of cladding with a layer of vanadium.

  2. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    NASA Astrophysics Data System (ADS)

    Jung, Myungwon; Mishra, Brajendra

    2018-02-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  3. Stability of rhombohedral phases in vanadium at high-pressure and high-temperature: first-principles investigations

    NASA Astrophysics Data System (ADS)

    Wang, Yi X.; Wu, Q.; Chen, Xiang R.; Geng, Hua Y.

    2016-09-01

    The pressure-induced transition of vanadium from BCC to rhombohedral structures is unique and intriguing among transition metals. In this work, the stability of these phases is revisited by using density functional theory. At finite temperatures, a novel transition of rhombohedral phases back to BCC phase induced by thermal electrons is discovered. This reentrant transition is found not driven by phonons, instead it is the electronic entropy that stabilizes the latter phase, which is totally out of expectation. Parallel to this transition, we find a peculiar and strong increase of the shear modulus C44 with increasing temperature. It is counter-intuitive in the sense that it suggests an unusual harding mechanism of vanadium by temperature. With these stability analyses, the high-pressure and finite-temperature phase diagram of vanadium is proposed. Furthermore, the dependence of the stability of RH phases on the Fermi energy and chemical environment is investigated. The results demonstrate that the position of the Fermi level has a significant impact on the phase stability, and follows the band-filling argument. Besides the Fermi surface nesting, we find that the localization/delocalization of the d orbitals also contributes to the instability of rhombohedral distortions in vanadium.

  4. Superconducting MgB2 wires with vanadium diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hušek, I.; Kováč, P.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.; Szundiová, B.

    2017-10-01

    Single-core MgB2 wires with a vanadium barrier and Cu stabilization have been made by the in situ powder-in-tube (PIT) and internal magnesium diffusion (IMD) into boron processes. Heat treatment of PIT wires was done at the temperature range of 650 °C-850 °C/30 min. Critical currents of differently treated MgB2/V/Cu wires have been measured and related with the structure of MgB2. It was found that critical current density of MgB2/V wire annealed above 700 °C decreases rapidly. The obtained results clearly show that vanadium is a well formable metal and can be applied as an effective diffusion barrier for MgB2 wires heat-treated at temperatures ≤700 °C. This temperature limit is well applicable for MgB2 wires with high current densities made by PIT and also by the IMD process.

  5. Transformers: the changing phases of low-dimensional vanadium oxide bronzes.

    PubMed

    Marley, Peter M; Horrocks, Gregory A; Pelcher, Kate E; Banerjee, Sarbajit

    2015-03-28

    In this feature article, we explore the electronic and structural phase transformations of ternary vanadium oxides with the composition MxV2O5 where M is an intercalated cation. The periodic arrays of intercalated cations ordered along quasi-1D tunnels or layered between 2D sheets of the V2O5 framework induce partial reduction of the framework vanadium atoms giving rise to charge ordering patterns that are specific to the metal M and stoichiometry x. This periodic charge ordering makes these materials remarkably versatile platforms for studying electron correlation and underpins the manifestation of phenomena such as colossal metal-insulator transitions, quantized charge corrals, and superconductivity. We describe current mechanistic understanding of these emergent phenomena with a particular emphasis on the benefits derived from scaling these materials to nanostructured dimensions wherein precise ordering of cations can be obtained and phase relationships can be derived that are entirely inaccessible in the bulk. In particular, structural transformations induced by intercalation are dramatically accelerated due to the shorter diffusion path lengths at nanometer-sized dimensions, which cause a dramatic reduction of kinetic barriers to phase transformations and facilitate interconversion between the different frameworks. We conclude by summarizing numerous technological applications that have become feasible due to recent advances in controlling the structural chemistry and both electronic and structural phase transitions in these versatile frameworks.

  6. Dual structural transition in small nanoparticles of Cu-Au alloy

    NASA Astrophysics Data System (ADS)

    Gafner, Yuri; Gafner, Svetlana; Redel, Larisa; Zamulin, Ivan

    2018-02-01

    Cu-Au alloy nanoparticles are known to be widely used in the catalysis of various chemical reactions as it was experimentally defined that in many cases the partial substitution of copper with gold increases catalytic activity. However, providing the reaction capacity of alloy nanoparticles the surface electronic structure strongly depends on their atomic ordering. Therefore, to theoretically determine catalytic properties, one needs to use a most real structural model complying with Cu-Au nanoparticles under various external influences. So, thermal stability limits were studied for the initial L12 phase in Cu3Au nanoalloy clusters up to 8.0 nm and Cu-Au clusters up to 3.0 nm at various degrees of Au atom concentration, with molecular dynamics method using a modified tight-binding TB-SMA potential. Dual structural transition L12 → FCC and further FCC → Ih is shown to be possible under the thermal factor in Cu3Au and Cu-Au clusters with the diameter up to 3.0 nm. The temperature of the structural transition FCC → Ih is established to decrease for small particles of Cu-Au alloy under the increase of Au atom concentration. For clusters with this structural transition, the melting point is found to be a linear increasing function of concentration, and for clusters without FCC → Ih structural transition, the melting point is a linear decreasing function of Au content. Thus, the article shows that doping Cu nanoclusters with Au atoms allows to control the forming structure as well as the melting point.

  7. Iron diminishes the in vitro biological effect of vanadium.

    EPA Science Inventory

    Mechanistic pathways underlying inflammatory injury following exposures to vanadium-containing compounds are not defined. We tested the postulate that the in vitro biological effect of vanadium results from its impact on iron homeostasis. Human bronchial epithelial (HBE) cells ex...

  8. Amphoteric Ion-Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All-Vanadium Redox Flow Batteries.

    PubMed

    Nibel, Olga; Rojek, Tomasz; Schmidt, Thomas J; Gubler, Lorenz

    2017-07-10

    All-vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy-storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion-exchange membranes, based on radiation-induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two-step functionalization to introduce cationic and anionic exchange sites, respectively. During long-term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Catalytic destruction of PCDD/Fs over vanadium oxide-based catalysts.

    PubMed

    Yu, Ming-Feng; Lin, Xiao-Qing; Li, Xiao-Dong; Yan, Mi; Prabowo, Bayu; Li, Wen-Wei; Chen, Tong; Yan, Jian-Hua

    2016-08-01

    Vanadium oxide-based catalysts were developed for the destruction of vapour phase PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans). A vapour phase PCDD/Fs generating system was designed to supply stable PCDD/Fs steam with initial concentration of 3.2 ng I-TEQ Nm(-3). Two kinds of titania (nano-TiO2 and conventional TiO2) and alumina were used as catalyst supports. For vanadium-based catalysts supported on nano-TiO2, catalyst activity is enhanced with operating temperature increasing from 160 to 300 °C and then reduces with temperature rising further to 350 °C. It is mainly due to the fact that high volatility of organic compounds at 350 °C suppresses adsorption of PCDD/Fs on catalysts surface and then further inhibits the reaction between catalyst and PCDD/Fs. The optimum loading of vanadium on nano-TiO2 support is 5 wt.% where vanadium oxide presents highly dispersed amorphous state according to the Raman spectra and XRD patterns. Excessive vanadium will block the pore space and form microcrystalline V2O5 on the support surface. At the vanadium loading of 5 wt.%, nano-TiO2-supported catalyst performs best on PCDD/Fs destruction compared to Al2O3 and conventional TiO2. Chemical states of vanadium in the fresh, used and reoxidized VOx(5 %)/TiO2 catalysts at different operating temperature are also analysed by XPS.

  10. Exploring the coordination change of vanadium and structure transformation of metavanadate MgV2O6 under high pressure

    PubMed Central

    Tang, Ruilian; Li, Yan; Xie, Shengyi; Li, Nana; Chen, Jiuhua; Gao, Chunxiao; Zhu, Pinwen; Wang, Xin

    2016-01-01

    Raman spectroscopy, synchrotron angle-dispersive X-ray diffraction (ADXRD), first-principles calculations, and electrical resistivity measurements were carried out under high pressure to investigate the structural stability and electrical transport properties of metavanadate MgV2O6. The results have revealed the coordination change of vanadium ions (from 5+1 to 6) at around 4 GPa. In addition, a pressure-induced structure transformation from the C2/m phase to the C2 phase in MgV2O6 was detected above 20 GPa, and both phases coexisted up to the highest pressure. This structural phase transition was induced by the enhanced distortions of MgO6 octahedra and VO6 octahedra under high pressure. Furthermore, the electrical resistivity decreased with pressure but exhibited different slope for these two phases, indicating that the pressure-induced structural phase transitions of MgV2O6 was also accompanied by the obvious changes in its electrical transport behavior. PMID:27924843

  11. Vanadium accumulation in carbonaceous rocks: A review of geochemical controls during deposition and diagenesis

    USGS Publications Warehouse

    Breit, G.N.; Wanty, R.B.

    1991-01-01

    Published data relevant to the geochemistry of vanadium were used to evaluate processes and conditions that control vanadium accumulation in carbonaceous rocks. Reduction, adsorption, and complexation of dissolved vanadium favor addition of vanadium to sediments rich in organic carbon. Dissolved vanadate (V(V)) species predominate in oxic seawater and are reduced to vanadyl ion (V(IV)) by organic compounds or H2S. Vanadyl ion readily adsorbs to particle surfaces and is added to the sediment as the particles settle. The large vanadium concentrations of rocks deposited in marine as compared to lacustrine environments are the result of the relatively large amount of vanadium provided by circulating ocean water compared to terrestrial runoff. Vanadium-rich carbonaceous rocks typically have high contents of organically bound sulfur and are stratigraphically associated with phosphate-rich units. A correspondence between vanadium content and organically bound sulfur is consistent with high activities of H2S during sediment deposition. Excess H2S exited the sediment into bottom waters and favored reduction of dissolved V(V) to V(IV) or possibly V(III). The stratigraphic association of vanadiferous and phosphatic rocks reflects temporal and spatial shifts in bottom water chemistry from suboxic (phosphate concentrated) to more reducing (euxinic?) conditions that favor vanadium accumulation. During diagenesis some vanadium-organic complexes migrate with petroleum out of carbonaceous rocks, but significant amounts of vanadium are retained in refractory organic matter or clay minerals. As carbon in the rock evolves toward graphite during metamorphism, vanadium is incorporated into silicate minerals. ?? 1991.

  12. Thymic cytoarchitecture changes in mice exposed to vanadium.

    PubMed

    Ustarroz-Cano, Martha; Garcia-Pelaez, Isabel; Cervantes-Yepez, Silvana; Lopez-Valdez, Nelly; Fortoul, Teresa I

    2017-12-01

    The thymus is a vital immune system organ wherein selection of T-lymphocytes occurs in a process regulated by dendritic and epithelial thymic cells. Previously, we have reported that in a mouse model of vanadium inhalation, a decrease in CD11c dendritic cells was observed. In the present study, we report on a thymic cortex-medulla distribution distortion in these hosts due to apparent effects of the inhaled vanadium on cytokeratin-5 (K5 + ) epithelial cells in the same mouse model - after 1, 2, and 4 weeks of exposure - by immunohistochemistry. These cells - together with dendritic cells - eliminate autoreactive T-cell clones and regulate the production of regulatory T-cells in situ. Because both cell types are involved in the negative selection of autoreactive clones, a potential for an increase in development of autoimmune conditions could be a possible consequence among individuals who might be exposed often to vanadium in air pollution, including dwellers of highly polluted cities with elevated levels of particulate matter onto which vanadium is often adsorbed.

  13. Ultrasonic Vibration and Rheocasting for Refinement of Mg-Zn-Y Alloy Reinforced with LPSO Structure

    NASA Astrophysics Data System (ADS)

    Lü, Shulin; Yang, Xiong; Hao, Liangyan; Wu, Shusen; Fang, Xiaogang; Wang, Jing

    2018-05-01

    In this work, ultrasonic vibration (UV) and rheo-squeeze casting was first applied on the Mg alloy reinforced with long period stacking ordered (LPSO) structure. The semisolid slurry of Mg-Zn-Y alloy was prepared by UV and processed by rheo-squeeze casting in succession. The effects of UV, Zr addition and squeeze pressure on microstructure of semisolid Mg-Zn-Y alloy were studied. The results revealed that the synergic effect of UV and Zr addition generated a finer microstructure than either one alone when preparing the slurries. Rheo-squeeze casting could significantly refine the LPSO structure and α-Mg matrix in Mg96.9Zn1Y2Zr0.1 alloy without changing the phase compositions or the type of LPSO structure. When the squeeze pressure increased from 0 to 400 MPa, the block LPSO structure was completely eliminated and the average thickness of LPSO structure decreased from 9.8 to 4.3 μm. Under 400 MPa squeeze pressure, the tensile strength and elongation of the rheocast Mg96.9Zn1Y2Zr0.1 alloy reached the maximum values, which were 234 MPa and 17.6%, respectively, due to its fine α-Mg matrix (α1-Mg and α2-Mg grains) and LPSO structure.

  14. Study of soft magnetic iron cobalt based alloys processed by powder injection molding

    NASA Astrophysics Data System (ADS)

    Silva, Aline; Lozano, Jaime A.; Machado, Ricardo; Escobar, Jairo A.; Wendhausen, Paulo A. P.

    As a near net shape process, powder injection molding (PIM) opens new possibilities to process Fe-Co alloys for magnetic applications. Due to the fact that PIM does not involve plastic deformation of the material during processing, we envisioned the possibility of eliminating vanadium (V), which is generally added to Fe-Co alloys to improve the ductility in order to enable its further shaping by conventional processes such as forging and cold rolling. In our investigation we have found out two main futures related to the elimination of V, which lead to a cost-benefit gain in manufacturing small magnetic components where high-saturation induction is needed at low frequencies. Firstly, the elimination of V enables the achievement of much better magnetic properties when alloys are processed by PIM. Secondly, a lower sintering temperature can be used when the alloy is processed starting with elemental Fe and Co powders without the addition of V.

  15. Geochemistry of vanadium (V) in Chinese coals.

    PubMed

    Liu, Yuan; Liu, Guijian; Qu, Qinyuan; Qi, Cuicui; Sun, Ruoyu; Liu, Houqi

    2017-10-01

    Vanadium in coals may have potential environmental and economic impacts. However, comprehensive knowledge of the geochemistry of V in coals is lacking. In this study, abundances, distribution and modes of occurrence of V are reviewed by compiling >2900 reported Chinese coal samples. With coal reserves in individual provinces as the weighting factors, V in Chinese coals is estimated to have an average abundance of 35.81 μg/g. Large variation of V concentration is observed in Chinese coals of different regions, coal-forming periods, and maturation ranks. According to the concentration coefficient of V in coals from individual provinces, three regions are divided across Chinese coal deposits. Vanadium in Chinese coals is probably influenced by sediment source and sedimentary environment, supplemented by late-stage hydrothermal fluids. Specifically, hydrothermal fluids have relatively more significant effect on the enrichment of V in local coal seams. Vanadium in coals is commonly associated with aluminosilicate minerals and organic matter, and the modes of V occurrence in coal depend on coal-forming environment and coal rank. The Chinese V emission inventory during coal combustion is estimated to be 4906 mt in 2014, accounting for 50.55 % of global emission. Vanadium emissions by electric power plants are the largest contributor.

  16. Investigation of High Temperature Ductility Losses in Alpha-Beta Titanium Alloys

    DTIC Science & Technology

    1988-04-01

    Gleeble simulation of GTAW thermal _ cycles, Figure 1.1 (6). They found that Ti-6AI-4V (Ti-64), Ti-6A1-2Nb-lTa-0.8Mo (Ti-6211), and Ti-6AI suffered...or weak beta stabilizers depending on the other alloying elements present. Vanadium, molybdenum, tantalum, niobium, chromium , silicon, copper...elements. Chromium , - silicon, copper, manganese, cobalt, iron, and hydrogen are all eutectic formers. A schematic binary phase diagram of a 0 beta

  17. Inducing microstructural changes in Nafion by incorporating graphitic carbon nitride to enhance the vanadium-blocking effect.

    PubMed

    Wu, Chunxiao; Lu, Shanfu; Zhang, Jin; Xiang, Yan

    2018-03-14

    Two-dimensional graphitic carbon nitride (g-C 3 N 4 ) nanosheets are introduced into a Nafion matrix to prepare a 'vanadium-blocking' recast Nafion membrane for vanadium redox flow battery (VRFB) applications. After 0.2 wt% g-C 3 N 4 nanosheets are incorporated, the vanadium ion permeability of the composite membrane decreases from 3.3 × 10 -7 cm 2 min -1 to 3.8 × 10 -9 cm 2 min -1 , which is a reduction of two orders of magnitude in comparison to the pristine recast Nafion membrane. This satisfactory result contributes to the physical blocking effect as well as the Donnan effect from the 2D morphology and functional amino groups of g-C 3 N 4 nanosheets. Notably, this work reveals that the g-C 3 N 4 nanosheets can help reinforce the vanadium-blocking effect by changing the microstructure of Nafion in addition to the well-known effects mentioned above. The g-C 3 N 4 nanosheets induce shrinkage in the original spherical structure of the ion cluster and generate a new lamellar structure. Correspondingly, the amorphous phase of Nafion is interrupted, and the membrane crystallinity is reduced. The VRFB with an optimized composite membrane achieves a high coulombic efficiency of 97% and an energy efficiency of 83% at a current density of 160 mA cm -2 . Meanwhile, the battery exhibited excellent lifetime stability during a 100 charge-discharge cycling test.

  18. Microstructural and opto-electrical properties of chromium nitride films implanted with vanadium ions

    NASA Astrophysics Data System (ADS)

    Novaković, M.; Traverse, A.; Popović, M.; Lieb, K. P.; Zhang, K.; Bibić, N.

    2012-07-01

    We report on modifications of 280-nm thin polycrystalline CrN layers caused by vanadium ion implantation. The CrN layers were deposited at 150°C by d.c. reactive sputtering on Si(100) wafers and then implanted at room temperature with 80-keV V+ ions to fluences of 1×1017 and 2×1017 ions/cm2. Rutherford backscattering spectroscopy, cross-sectional transmission electron microscopy, and X-ray diffraction were used to characterize changes in the structural properties of the films. Their optical and electrical properties were analyzed by infrared spectroscopy in reflection mode and electrical resistivity measurements. CrN was found to keep its cubic structure under the conditions of vanadium ion implantation used here. The initially partially non-metallic CrN layer displays metallic character under implantation, which may be related to the possible formation of Cr1-x V x N.

  19. NASA-UVA Light Aerospace Alloy and Structures Technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Starke, Edgar A., Jr.; Gangloff, Richard P.; Herakovich, Carl T.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1995-01-01

    The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites, and thermal gradient structures in collaboration with NASA-Langley researchers. The general aim is to produce relevant data and basic understanding of material mechanical response, environment/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated students for aerospace technologies. Specific technical objectives are presented for each of the following research projects: time-temperature dependent fracture in advanced wrought ingot metallurgy, and spray deposited aluminum alloys; cryogenic temperature effects on the deformation and fracture of Al-Li-Cu-In alloys; effects of aging and temperature on the ductile fracture of AA2095 and AA2195; mechanisms of localized corrosion in alloys 2090 and 2095; hydrogen interactions in aluminum-lithium alloys 2090 and selected model alloys; mechanisms of deformation and fracture in high strength titanium alloys (effects of temperature and hydrogen and effects of temperature and microstructure); evaluations of wide-panel aluminum alloy extrusions; Al-Si-Ge alloy development; effects of texture and precipitates on mechanical property anisotropy of Al-Cu-Mg-X alloys; damage evolution in polymeric composites; and environmental effects in fatigue life prediction - modeling crack propagation in light aerospace alloys.

  20. Crystal structure and equation of state of Fe-Si alloys at super-Earth core conditions

    PubMed Central

    Fratanduono, Dayne E.; Coppari, Federica; Newman, Matthew G.; Duffy, Thomas S.

    2018-01-01

    The high-pressure behavior of Fe alloys governs the interior structure and dynamics of super-Earths, rocky extrasolar planets that could be as much as 10 times more massive than Earth. In experiments reaching up to 1300 GPa, we combine laser-driven dynamic ramp compression with in situ x-ray diffraction to study the effect of composition on the crystal structure and density of Fe-Si alloys, a potential constituent of super-Earth cores. We find that Fe-Si alloy with 7 weight % (wt %) Si adopts the hexagonal close-packed structure over the measured pressure range, whereas Fe-15wt%Si is observed in a body-centered cubic structure. This study represents the first experimental determination of the density and crystal structure of Fe-Si alloys at pressures corresponding to the center of a ~3–Earth mass terrestrial planet. Our results allow for direct determination of the effects of light elements on core radius, density, and pressures for these planets. PMID:29707632

  1. Phonon triggered rhombohedral lattice distortion in vanadium at high pressure

    DOE PAGES

    Antonangeli, Daniele; Farber, Daniel L.; Bosak, Alexei; ...

    2016-08-19

    In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Lastly, ourmore » results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V.« less

  2. Evolution of twinning in extruded AZ31 alloy with bimodal grain structure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Garcés, G., E-mail: ggarces@cenim.csic.es

    2017-04-15

    Twinning in extruded AZ31 alloy with a bimodal grain structure is studied under compression along the extrusion direction. This study has combined in-situ measurements during the compression tests by Synchrotron Radiation Diffraction and Acoustic Emission techniques and the evaluation of the microstructure and texture in post-mortem compression samples deformed at different strains. The microstructure of the alloy is characterized by the coexistence of large areas of fine dynamic recrystallized grains and coarse non-recrystallized grains elongated along extrusion direction. Twinning occurs initially in large elongated grains before the macroscopic yield stress which is controlled by the twinning in equiaxed dynamically recrystallizedmore » grains. - Highlights: • The AZ31 extruded at low temperature exhibits a bimodal grains structure. • Twinning takes place before macroscopic yielding in coarse non-DRXed grains. • DRXed grains controls the beginning of plasticity in magnesium alloys with bimodal grain structure.« less

  3. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1996-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. Three research areas are being actively investigated, including: (1) Mechanical and environmental degradation mechanisms in advanced light metals, (2) Aerospace materials science, and (3) Mechanics of materials for light aerospace structures.

  4. Switching adhesion forces by crossing the metal–insulator transition in Magnéli-type vanadium oxide crystals

    PubMed Central

    Klemm, Matthias; Horn, Siegfried; Woydt, Mathias

    2011-01-01

    Summary Magnéli-type vanadium oxides form the homologous series VnO2 n -1 and exhibit a temperature-induced, reversible metal–insulator first order phase transition (MIT). We studied the change of the adhesion force across the transition temperature between the cleavage planes of various vanadium oxide Magnéli phases (n = 3 … 7) and spherical titanium atomic force microscope (AFM) tips by systematic force–distance measurements with a variable-temperature AFM under ultrahigh vacuum conditions (UHV). The results show, for all investigated samples, that crossing the transition temperatures leads to a distinct change of the adhesion force. Low adhesion corresponds consistently to the metallic state. Accordingly, the ability to modify the electronic structure of the vanadium Magnéli phases while maintaining composition, stoichiometry and crystallographic integrity, allows for relating frictional and electronic material properties at the nano scale. This behavior makes the vanadium Magnéli phases interesting candidates for technology, e.g., as intelligent devices or coatings where switching of adhesion or friction is desired. PMID:21977416

  5. CATALYTIC PROMOTION OF THE ADSORPTION OF VANADIUM ON AN ANIONIC EXCHANGE RESIN

    DOEpatents

    Bailes, R.H.; Ellis, D.A.

    1958-08-26

    An improvement in the process for the recovery of vanadium from acidic phosphatic solutions is presented. In this process the vanadium is first oxidized to the pentavaleat state, and is then separated by contacting such solutions with an anion exchange resin whereby adsorption of the complexed pentavalent vanadium is effected. The improvement lies in the fact that adsorp tion of the vanadium complex by the anion exchange resin is promoted and improved by providing fiuoride ions in solution to be contacted.

  6. Mechanical properties and the electronic structure of transition of metal alloys

    NASA Technical Reports Server (NTRS)

    Arsenault, R. J.; Drew, H. D.

    1977-01-01

    This interdiscipline research program was undertaken in an effort to investigate the relationship between the mechanical strength of Mo based alloys with their electronic structure. Electronic properties of these alloys were examined through optical studies, and the classical solid solution strengthening mechanisms were considered, based on size and molecular differences to determine if these mechanisms could explain the hardness data.

  7. [Effect of vanadium exposure on neurobehavioral function in workers].

    PubMed

    Zhu, C W; Liu, Y X; Huang, C J; Gao, W; Hu, G L; Li, J; Zhang, Q; Lan, Y J

    2016-02-20

    To establish the comprehensive indicators for neurobehavioral function test, and to investigate the possible adverse effect of long-time vanadium exposure on neurobehavioral function and its features in workers. From July to November, 2012, The Neurobehavioral Core Test Battery(NCTB) recommended by WHO was used to conduct tests for 128 workers in vanadium exposure group and 128 workers in control group. The t-test and analysis of covariance were used to compare the differences in each indicator in NCTB between different populations, and the principal component analysis was used to establish the comprehensive neurobehavioral index(NBI) and investigate the effect of vanadium on workers' neurobehavioral function. The vanadium exposure group had significantly lower visual retention score(6.9±1.9), digit span(order) score(8.9±2.9), lifting and turning dexterity(the non-handed hand) score (14.1±3.6), pursuit aiming test(the number of correct dots) score(65.7±24.8), and digit symbol score (31.1±15.0) than the control group (8.2±1.3, 9.4±2.7, 15.5±3.0, 76.5±23.8, and 33.7±9.5)(all P<0.05). The vanadium exposure group also had a significantly lower NBI than the control group(-0.167±0.602 vs 0.168±0.564, P<0.05). Long-term vanadium exposure can influence the workers' neurobehavioral function, with the manifestations of decreased hearing and visual memory, movement velocity, accuracy, and coordination.

  8. Influence of aerothermoacoustic treatment on the structure and the properties of a TS6 titanium alloy

    NASA Astrophysics Data System (ADS)

    Remshev, E. Yu.; Danilin, G. A.; Vorob'eva, G. A.; Kuznetsov, V. V.

    2017-01-01

    The influence of standard heat or aerothermoacoustic treatment on the structure and the properties of a TS6 titanium alloy is considered. The interrelation between variations in the structure, the grain size, and the properties of the alloy has been detected. The possibilities of aerothermoacoustic treatment to provide a simultaneous increase in the strength and the plasticity of a TS6 alloy upon refining of its grain structure in the course of microplastic deformation and recrystallization are demonstrated.

  9. A-15 Superconducting composite wires and a method for making

    DOEpatents

    Suenaga, Masaki; Klamut, Carl J.; Luhman, Thomas S.

    1984-01-01

    A method for fabricating superconducting wires wherein a billet of copper containing filaments of niobium or vanadium is rolled to form a strip which is wrapped about a tin-alloy core to form a composite. The alloy is a tin-copper alloy for niobium filaments and a gallium-copper alloy for vanadium filaments. The composite is then drawn down to a desired wire size and heat treated. During the heat treatment process, the tin in the bronze reacts with the niobium to form the superconductor niobium tin. In the case where vanadium is used, the gallium in the gallium bronze reacts with the vanadium to form the superconductor vanadium gallium. This new process eliminates the costly annealing steps, external tin plating and drilling of bronze ingots required in a number of prior art processes.

  10. Wrapping process for fabrication of A-15 superconducting composite wires

    DOEpatents

    Suenaga, M.; Klamut, C.J.; Luhman, T.S.

    1980-08-15

    A method for fabricating superconducting wires wherein a billet of copper containing filaments of niobium or vanadium is rolled to form a strip which is wrapped about a tin-alloy core to form a composite. The alloy is a tin-copper alloy for niobium filaments and a gallium-copper alloy for vanadium filaments. The composite is then drawn down to a desired wire size and heat treated. During the heat treatment process, the tin in the bronze reacts with the niobium to form the superconductor niobium tin. In the case where vanadium is used, the gallium in the gallium bronze reacts with the vanadium to form the superconductor vanadium gallium. This new process eliminates the costly annealing steps, external tin plating and drilling of bronze ingots required in a number of prior art processes.

  11. Structure and Mechanical Properties of As-Cast Ti-5Sn-xMo Alloys.

    PubMed

    Yu, Hsing-Ning; Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang; Ho, Wen-Fu

    2017-04-27

    Ti-5Sn- x Mo ( x = 0, 1, 3, 5, 7.5, 10, 12.5, 15, 17.5, and 20 wt %) alloys were designed and prepared for application as implant materials with superior mechanical properties. The results demonstrated that the crystal structure and mechanical properties of Ti-5Sn- x Mo alloys are highly affected by their Mo content. The as-cast microstructures of Ti-5Sn- x Mo alloys transformed in the sequence of phases α' → α″ → β, and the morphologies of the alloys changed from a lath structure to an equiaxed structure as the Mo content increased. The α″-phase Ti-5Sn-7.5Mo (80 GPa) and β-phase Ti-5Sn-10Mo (85 GPa) exhibited relatively low elastic moduli and had excellent elastic recovery angles of 27.4° and 37.8°, respectively. Furthermore, they exhibited high ductility and moderate strength, as evaluated using the three-point bending test. Search for a more suitable implant material by this study, Ti-5Sn- x Mo alloys with 7.5 and 10 wt % Mo appear to be promising candidates because they demonstrate the optimal combined properties of microhardness, ductility, elastic modulus, and elastic recovery capability.

  12. Structure and Mechanical Properties of As-Cast Ti–5Sn–xMo Alloys

    PubMed Central

    Yu, Hsing-Ning; Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang; Ho, Wen-Fu

    2017-01-01

    Ti–5Sn–xMo (x = 0, 1, 3, 5, 7.5, 10, 12.5, 15, 17.5, and 20 wt %) alloys were designed and prepared for application as implant materials with superior mechanical properties. The results demonstrated that the crystal structure and mechanical properties of Ti–5Sn–xMo alloys are highly affected by their Mo content. The as-cast microstructures of Ti–5Sn–xMo alloys transformed in the sequence of phases α′ → α″ → β, and the morphologies of the alloys changed from a lath structure to an equiaxed structure as the Mo content increased. The α″-phase Ti–5Sn–7.5Mo (80 GPa) and β-phase Ti–5Sn–10Mo (85 GPa) exhibited relatively low elastic moduli and had excellent elastic recovery angles of 27.4° and 37.8°, respectively. Furthermore, they exhibited high ductility and moderate strength, as evaluated using the three-point bending test. Search for a more suitable implant material by this study, Ti–5Sn–xMo alloys with 7.5 and 10 wt % Mo appear to be promising candidates because they demonstrate the optimal combined properties of microhardness, ductility, elastic modulus, and elastic recovery capability. PMID:28772820

  13. Theoretical analysis and experiments for the carburization of vanadium-bearing hot metal

    NASA Astrophysics Data System (ADS)

    Ma, Deng; Wu, Wei; Dai, Shifan; Liu, Zhibin

    2018-01-01

    In this study, the feasibility of the carburization of vanadium-bearing hot metal was first investigated by thermodynamic analysis. Next, three carburizers, namely a low-nitrogen carburizer, anthracite, and coke, were used for carburization of 500 g of vanadium-bearing hot metal at 1450 °C, 1500 °C, and 1550 °C, respectively. The carbon increments for the low-nitrogen carburizer, anthracite and coke followed decreasing order in the temperature range from 1450 °C to 1550 °C. Anthracite was the most cost-effective carburizer. Hence, anthracite is used in pilot-scale experiments of the vanadium-bearing hot metal (100 kg and 200 kg). Finally, vanadium extraction experiments of the vanadium-bearing hot metal were carried out in a top-bottom-combined blowing induction furnace. It is proved that the average superheat degree of semi-steel increases from 100 °C to 198 °C by the carburization of vanadium-containing hot metal. Foundation Item: Item Sponsored by National Science Foundation of China (51674092)

  14. Structural Evolution of a Ni Alloy Surface During High-Temperature Oxidation

    DOE PAGES

    Oleksak, Richard P.; Carney, Casey S.; Holcomb, Gordon R.; ...

    2017-11-20

    We show that considerable structural transformations occur at a Ni alloy surface during the transient stages of high-temperature oxidation. This was demonstrated by exposing the alloy to high-temperature CO 2 for short times at both atmospheric and supercritical pressures. A protective Cr-rich oxide layer formed after only 5 min at 700 °C and persisted for longer exposures up to 500 h. Voids formed and grew over time by the condensation of metal vacancies generated during oxidation, while the alloy surface recrystallized after sufficient oxidation had occurred. The oxygen potential established at the oxide/alloy interface led to oxidation along the newlymore » formed grain boundaries as well as adjacent to and inside of the voids. Al, the most stable oxide-former and present at low concentration in the alloy, was preferentially oxidized in these regions. Furthermore, the results provide an improved understanding of the internal oxidation of Al and its role in enhancing scale adhesion for this class of Ni alloys.« less

  15. Effect of gallium alloying on the structure, the phase composition, and the thermoelastic martensitic transformations in ternary Ni-Mn-Ga alloys

    NASA Astrophysics Data System (ADS)

    Belosludtseva, E. S.; Kuranova, N. N.; Marchenkova, E. B.; Popov, A. G.; Pushin, V. G.

    2016-04-01

    The effect of gallium alloying on the structure, the phase composition, and the properties of quasibinary Ni50Mn50- z Ga z (0 ⩽ z ⩽ 25 at %) alloys is studied over a wide temperature range. The influence of the alloy composition on the type of crystal structure in high-temperature austenite and martensite and the critical martensitic transformation temperatures is analyzed. A general phase diagram of the magnetic and structural transformations in the alloys is plotted. The temperature-concentration boundaries of the B2 and L21 superstructures in the austenite field, the tetragonal L10 (2 M) martensite, and the 10 M and 14 M martensite phases with complex multilayer crystal lattices are found. The predominant morphology of martensite is shown to be determined by the hierarchy of the packets of thin coherent lamellae of nano- and submicrocrystalline crystals with planar habit plane boundaries close to {011} B2. Martensite crystals are twinned along one of the 24 24{ {011} }{< {01bar 1} rangle _{B2}} "soft" twinning shear systems, which provides coherent accommodation of the martensitic transformation-induced elastic stresses.

  16. Structural, optical, and spin properties of hydrogenated amorphous silicon-germanium alloys

    NASA Astrophysics Data System (ADS)

    Stutzmann, M.; Street, R. A.; Tsai, C. C.; Boyce, J. B.; Ready, S. E.

    1989-07-01

    We report on a detailed study of structural and electronic properties of hydrogenated amorphous silicon-germanium alloys deposited by rf glow discharge from SiH4 and GeH4 in a diode reactor. The chemical composition of the alloys is related to the deposition conditions, with special emphasis on preferential incorporation of Ge into the solid phase and on the role of inert dilutant gases. Hydrogen bonding in the alloys is investigated with nuclear magnetic resonance and vibrational (Raman and infrared) spectroscopy. The optical properties of a-SiGe:H samples deposited under optimal conditions are analyzed with the help of subgap absorption measurements and band-tail luminescence for the entire range of alloy composi-tions. A large part of the article describes an investigation of the electron-spin-resonance response of undoped alloys. The spin density associated with dangling bond defects localized on Si and Ge atoms has been measured as a function of alloy composition for optimized material. In addition, the dependence of the two defect densities on the detailed deposition conditions (rf power, substrate temperature, and dilution) has been determined in a systematic way for alloys deposited from a plasma with a fixed SiH4/GeH4ratio. The results of this study, especially the preferential creation of Ge dangling bonds, are discussed in the context of our structural data. Furthermore, spin resonance is employed to investigate the light-induced degradation (Staebler-Wronski effect) of a-SiGe:H. Finally, the changes of the spin-resonance spectra of a-Si0.7 Ge0.3 :H upon substitutional doping with phosphorus and boron have been obtained experimentally, and are used to construct a model for the electronic density of states in this material.

  17. Vanadium proton exchange membrane water electrolyser

    NASA Astrophysics Data System (ADS)

    Noack, Jens; Roznyatovskaya, Nataliya; Pinkwart, Karsten; Tübke, Jens

    2017-05-01

    In order to reverse the reactions of vanadium oxygen fuel cells and to regenerate vanadium redox flow battery electrolytes that have been oxidised by atmospheric oxygen, a vanadium proton exchange membrane water electrolyser was set up and investigated. Using an existing cell with a commercial and iridium-based catalyst coated membrane, it was possible to fully reduce V3.5+ and V3+ solutions to V2+ with the formation of oxygen and with coulomb efficiencies of over 96%. The cell achieved a maximum current density of 75 mA/cm2 during this process and was limited by the proximity of the V(III) reduction to the hydrogen evolution reaction. Due to the specific reaction mechanisms of V(IV) and V(III) ions, V(III) solutions were reduced with an energy efficiency of 61%, making this process nearly twice as energy efficient as the reduction of V(IV) to V(III). Polarisation curves and electrochemical impedance spectroscopy were used to further investigate the losses of half-cell reactions and to find ways of further increasing efficiency and performance levels.

  18. The Vanadium Iodoperoxidase from the Marine Flavobacteriaceae Species Zobellia galactanivorans Reveals Novel Molecular and Evolutionary Features of Halide Specificity in the Vanadium Haloperoxidase Enzyme Family

    PubMed Central

    Fournier, Jean-Baptiste; Rebuffet, Etienne; Delage, Ludovic; Grijol, Romain; Meslet-Cladière, Laurence; Rzonca, Justyna; Potin, Philippe; Michel, Gurvan; Czjzek, Mirjam

    2014-01-01

    Vanadium haloperoxidases (VHPO) are key enzymes that oxidize halides and are involved in the biosynthesis of organo-halogens. Until now, only chloroperoxidases (VCPO) and bromoperoxidases (VBPO) have been characterized structurally, mainly from eukaryotic species. Three putative VHPO genes were predicted in the genome of the flavobacterium Zobellia galactanivorans, a marine bacterium associated with macroalgae. In a phylogenetic analysis, these putative bacterial VHPO were closely related to other VHPO from diverse bacterial phyla but clustered independently from eukaryotic algal VBPO and fungal VCPO. Two of these bacterial VHPO, heterogeneously produced in Escherichia coli, were found to be strictly specific for iodide oxidation. The crystal structure of one of these vanadium-dependent iodoperoxidases, Zg-VIPO1, was solved by multiwavelength anomalous diffraction at 1.8 Å, revealing a monomeric structure mainly folded into α-helices. This three-dimensional structure is relatively similar to those of VCPO of the fungus Curvularia inaequalis and of Streptomyces sp. and is superimposable onto the dimeric structure of algal VBPO. Surprisingly, the vanadate binding site of Zg-VIPO1 is strictly conserved with the fungal VCPO active site. Using site-directed mutagenesis, we showed that specific amino acids and the associated hydrogen bonding network around the vanadate center are essential for the catalytic properties and also the iodide specificity of Zg-VIPO1. Altogether, phylogeny and structure-function data support the finding that iodoperoxidase activities evolved independently in bacterial and algal lineages, and this sheds light on the evolution of the VHPO enzyme family. PMID:25261522

  19. A nested case-control study of prenatal vanadium exposure and low birthweight.

    PubMed

    Jiang, Minmin; Li, Yuanyuan; Zhang, Bin; Zhou, Aifen; Zheng, Tongzhang; Qian, Zhengmin; Du, Xiaofu; Zhou, Yanqiu; Pan, Xinyun; Hu, Jie; Wu, Chuansha; Peng, Yang; Liu, Wenyu; Zhang, Chuncao; Xia, Wei; Xu, Shunqing

    2016-09-01

    Is prenatal vanadium exposure associated with adverse birth outcomes? The odds of low birthweight (LBW) are increased 2.23-fold in mothers with a urinary vanadium of ≥2.91 μg/g creatinine compared with that in mothers with a urinary vanadium of ≤1.42 μg/g creatinine. Human exposure to vanadium occurs through intake of food, water and polluted air. Vanadium has been suggested to have fetotoxicity and developmental toxicity in animal studies, and epidemiological studies have reported an association between a decrease in birthweight and vanadium exposure estimated from particulate matter. A nested case-control study involving 816 study participants (204 LBW cases and 612 matched controls) was conducted with data from the prospective Healthy Baby Cohort between 2012 and 2014 in the province of Hubei, China. Vanadium concentrations in 816 maternal urine samples collected before delivery [the median gestational age was 39 weeks (range 27-42 weeks)] were measured by inductively coupled plasma mass spectrometry. Information on the infants' birth outcomes was obtained from medical records. Conditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs). The median urinary vanadium concentration of the cases was much higher than that of the controls (3.04 μg/g creatinine versus 1.93 μg/g creatinine). The results revealed a significant positive trend between the odds of LBW and level of maternal urinary vanadium [relative to the lowest tertile; adjusted OR = 1.69 (95% CI: 0.92, 3.10) for the medium tertile; adjusted OR = 2.23 (95% CI: 1.23, 4.05) for the highest tertile; P-trend = 0.02]. Additionally, the association was not modified by maternal age (P for heterogeneity = 0.70) or infant gender (P for heterogeneity = 0.21). The maternal urine sample was collected before labor, and the maternal urinary vanadium levels measured at one point in time may not accurately reflect the vanadium burden during the entire pregnancy

  20. Electronic structure studies of a clock-reconstructed Al/Pd(1 0 0) surface alloy

    NASA Astrophysics Data System (ADS)

    Kirsch, Janet E.; Tainter, Craig J.

    We have employed solid-state Fenske-Hall band structure calculations to examine the electronic structure of Al/Pd(1 0 0), a surface alloy that undergoes a reconstruction, or rearrangement, of the atoms in the top few surface layers. Surface alloys are materials that consist primarily of a single elemental metal, but which have a bimetallic surface composition that is only a few atomic layers in thickness. The results of this study indicate that reconstruction into a clock configuration simultaneously optimizes the intralayer bonding within the surface plane and the bonding between the first and second atomic layers. These results also allow us to examine the fundamental relationship between the electronic and physical structures of this reconstructed surface alloy.

  1. Computational modeling of high-entropy alloys: Structures, thermodynamics and elasticity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gao, Michael C.; Gao, Pan; Hawk, Jeffrey A.

    This study provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi > CoOsReRu > MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if themore » same crystal structure is used for the elements and the alloy. The deviation in the calculated elastic properties from ROM for select alloys is small but is susceptible to the choice used for the structures of pure components.« less

  2. Computational modeling of high-entropy alloys: Structures, thermodynamics and elasticity

    DOE PAGES

    Gao, Michael C.; Gao, Pan; Hawk, Jeffrey A.; ...

    2017-10-12

    This study provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi > CoOsReRu > MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if themore » same crystal structure is used for the elements and the alloy. The deviation in the calculated elastic properties from ROM for select alloys is small but is susceptible to the choice used for the structures of pure components.« less

  3. Plasma assisted synthesis of vanadium pentoxide nanoplates

    NASA Astrophysics Data System (ADS)

    Singh, Megha; Sharma, Rabindar Kumar; Kumar, Prabhat; Reddy, G. B.

    2015-08-01

    In this work, we report the growth of α-V2O5 (orthorhombic) nanoplates on glass substrate using plasma assisted sublimation process (PASP) and Nickel as catalyst. 100 nm thick film of Ni is deposited over glass substrate by thermal evaporation process. Vanadium oxide nanoplates have been deposited treating vanadium metal foil under high vacuum conditions with oxygen plasma. Vanadium foil is kept at fixed temperature growth of nanoplates of V2O5 to take place. Samples grown have been studied using XPS, XRD and HRTEM to confirm the growth of α-phase of V2O5, which revealed pure single crystal of α- V2O5 in orthorhombic crystallographic plane. Surface morphological studies using SEM and TEM show nanostructured thin film in form of plates. Uniform, vertically aligned randomly oriented nanoplates of V2O5 have been deposited.

  4. Stability of rhombohedral phases in vanadium at high-pressure and high-temperature: first-principles investigations

    PubMed Central

    Wang, Yi X.; Wu, Q.; Chen, Xiang R.; Geng, Hua Y.

    2016-01-01

    The pressure-induced transition of vanadium from BCC to rhombohedral structures is unique and intriguing among transition metals. In this work, the stability of these phases is revisited by using density functional theory. At finite temperatures, a novel transition of rhombohedral phases back to BCC phase induced by thermal electrons is discovered. This reentrant transition is found not driven by phonons, instead it is the electronic entropy that stabilizes the latter phase, which is totally out of expectation. Parallel to this transition, we find a peculiar and strong increase of the shear modulus C44 with increasing temperature. It is counter-intuitive in the sense that it suggests an unusual harding mechanism of vanadium by temperature. With these stability analyses, the high-pressure and finite-temperature phase diagram of vanadium is proposed. Furthermore, the dependence of the stability of RH phases on the Fermi energy and chemical environment is investigated. The results demonstrate that the position of the Fermi level has a significant impact on the phase stability, and follows the band-filling argument. Besides the Fermi surface nesting, we find that the localization/delocalization of the d orbitals also contributes to the instability of rhombohedral distortions in vanadium. PMID:27581551

  5. Structure and Properties of Titanium Tantalum Alloys for Biocompatibility

    NASA Astrophysics Data System (ADS)

    Huber, Daniel E.

    In this thesis, the phase stability and elastic modulus of Ti-Ta simple binary alloys as well as alloys with small additions of ternary elements have been studied. The binary alloy from a nominal 8 to 28 wt.% Ta was first explored using a combinatorial approach. This approach included Laser Engineered Net Shape (LENSTM) processing of materials and subsequent characterization by instrumented indentation and site specific Transmission Electron Microscopy (TEM). The composition range of 15 to 75 wt.% Ta was further explored by more traditional methods that included vacuum arc melting high purity elements, X-Ray Diffraction (XRD) and modulus measurements made by ultrasonic methods. Beyond the simple binary, alloys with low levels of ternary elements, oxygen, aluminum, zirconium and small additions of rare earth oxides were investigated. The crystal structure with space group Cmcm was chosen for it applicability with P63/mmc and Im-3¯m sub group / super group symmetry. This provides a consistent crystal structure framework for the purpose of studying the alpha to beta transformation pathway and associated alpha' and alpha'' martensitic phases. In this case, the pathway is defined by both the lattice parameters and the value of the parameter "y", where the parameter "y" describes the atomic positions of the [002]alpha plane. It was found that the lattice parameter changes in the Ti-Ta binary alloys are similar to structures reported for compositions in the Ti-Nb system of similar atomic percentages. Although samples produced by the LENSTM; process and characterized by instrumented indentation demonstrated the correct trends in modulus behavior, absolute agreement was not seen with modulus values published in literature. Alloys of the binary Ti-Ta system produced from high purity materials do indeed show close agreement with literature where there exist two minima of modulus near the compositions of Ti-28Ta wt.% and Ti-68Ta wt.%. These two minima occur at the discreet

  6. Photoelectron spectroscopic study on the electronic structures of the dental gold alloys and their interaction with L-cysteine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ogawa, Koji; Takahashi, Kazutoshi; Azuma, Junpei

    The valence electronic structures of the dental gold alloys, type 1, type 3, and K14, and their interaction with L-cysteine have been studied by ultraviolet photoelectron spectroscopy with synchrotron radiation. It was found that the electronic structures of the type-1 and type-3 dental alloys are similar to that of polycrystalline Au, while that of the K14 dental alloy is much affected by Cu. The peak shift and the change in shape due to alloying are observed in all the dental alloys. It is suggested that the new peak observed around 2 eV for the L-cysteine thin films on all themore » dental alloys may be due to the bonding of S 3sp orbitals with the dental alloy surfaces, and the Cu-S bond, as well as the Au-S and Au-O bonds, may cause the change in the electronic structure of the L-cysteine on the alloys.« less

  7. Characterization and Electrochromic Properties of Vanadium Oxide Thin Films Prepared via Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Mousavi, M.; Kompany, A.; Shahtahmasebi, N.; Bagheri-Mohagheghi, M.-M.

    2013-08-01

    Vanadium oxide thin films were grown on glass substrates using spray pyrolysis technique. The effects of substrate temperature, vanadium concentration in the initial solution and the solution spray rate on the nanostructural and the electrochromic properties of deposited films are investigated. Characterization and the electrochromic measurements were carried out using X-ray diffraction, scanning electron microscopy and cyclic voltammogram. XRD patterns showed that the prepared films have polycrystalline structure and are mostly mixed phases of orthorhombic α-V2O5 along with minor β-V2O5 and V4O9 tetragonal structures. The preferred orientation of the deposited films was found to be along [101] plane. The cyclic voltammogram results obtained for different samples showed that only the films with 0.2 M solution concentration, 5 ml/min solution spray rate and 450°C substrate temperature exhibit two-step electrochromic properties. The results show a correlation between cycle voltammogram, morphology and resistance of the films.

  8. Improvement of chemical composition, structure and mechanical properties of heat-resistant chromium-nickel alloy

    NASA Astrophysics Data System (ADS)

    Varlamova, S.; Trushnikova, A.; Rumyantsev, B.; Butrim, V.; Simonov, V.

    2018-04-01

    A thermodynamic analysis of a multicomponent system of the Cr-Ni alloy (Cr-32Ni-1,5W-0,25V-0,5Ti) with small additions of refractory metals was carried out. The microstructure and phase composition of the base alloy (I) and alloy with additional alloying (II) were studied. The effect of additives on the mechanical properties of the Cr-Ni alloy at 20, 900 and 1080 °C was shown. The microstructure of alloys I and II was studied in the fracture zone of samples after tensile tests at different temperatures. We studied the effect of small additives on the microstructure of alloys and changes in the morphology of the structural components (phases) as a function of temperature and degree of deformation.

  9. Structural properties of medium-range order in CuNiZr alloy

    NASA Astrophysics Data System (ADS)

    Gao, Tinghong; Hu, Xuechen; Xie, Quan; Li, Yidan; Ren, Lei

    2017-10-01

    The evolution characteristics of icosahedral clusters during the rapid solidification of Cu50Ni10Zr40 alloy at cooling rate of 1011 K s-1 are investigated based on molecular dynamics simulations. The structural properties of the short-range order and medium-range order of Cu50Ni10Zr40 alloy are analyzed by several structural characterization methods. The results reveal that the icosahedral clusters are the dominant short-range order structure, and that they assemble themselves into medium-range order by interpenetrating connections. The different morphologies of medium-range order are found in the system and include chain, triangle, tetrahedral, and their combination structures. The tetrahedral morphologies of medium-range order have excellent structural stability with decreasing temperature. The Zr atoms are favorable to form longer chains, while the Cu atoms are favorable to form shorter chains in the system. Those chains interlocked with each other to improve the structural stability.

  10. Particle Characteristics and Densification of W6Mo5Cr4V2Co5Nb Overspray Powder

    NASA Astrophysics Data System (ADS)

    Pi, Ziqiang; Lu, Xin; Yang, Fei; Liu, Bowen; Jia, Chengchang; Qu, Xuanhui; Zheng, Wei; Wu, Lizhi; Shao, Qingli

    2018-05-01

    W6Mo5Cr4V2Co5Nb (825 K) alloy was prepared by a two-step sintering process from overspray 825 K alloy powder. The overspray powder characteristics and the microstructure and mechanical properties of the as-sintered 825 K alloy were investigated. Results showed that two types of carbides formed a network structure in the overspray powder, which had spherical or quasispherical shape: one was MC carbide that was rich in vanadium (V), and the other was M2C carbide enriched with vanadium (V) and tungsten (W). The sintered 825 K alloy contained M6C and MC carbides, of which M6C was rich in tungsten (W) and molybdenum (Mo), and both of these two carbides were uniformly distributed in the alloy matrix. The alloy had relative density of 98.43%, hardness of HRC 51.8, and superior bending strength of 2042 MPa. These mechanical properties can meet the requirements of most engineering applications.

  11. Vanadium Nitrogenase Reduces CO*

    PubMed Central

    Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W.

    2011-01-01

    Vanadium nitrogenase not only reduces dinitrogen to ammonia but also reduces carbon monoxide to ethylene, ethane, and propane. The parallelism between the two reactions suggests a potential link in mechanism and evolution between the carbon and nitrogen cycles on Earth. PMID:20689010

  12. Vanadium Exposure-Induced Neurobehavioral Alterations among Chinese Workers

    PubMed Central

    Li, Hong; Zhou, Dinglun; Zhang, Qin; Feng, Chengyong; Zheng, Wei; He, Keping; Lan, Yajia

    2014-01-01

    Vanadium-containing products are manufactured and widely used in the modern industry. Yet the neurobehavioral toxicity due to occupational exposure to vanadium remained elusive. This cross-sectional study was designed to examine the neurotoxic effects of occupational vanadium exposure. A total of 463 vanadium-exposed workers (exposed group) and 251 non-exposed workers (control group) were recruited from a Steel and Iron Group in Sichuan, China. A WHO-recommended neurobehavioral core test battery (NCTB) and event-related auditory evoked potentials test (P300) were used to assess the neurobehavioral functions of all study subjects. A general linear model was used to compare outcome scores between the two groups while controlling for possible confounders. The exposed group showed a statistically significant neurobehavioral alteration more than the control group in the NCTB tests. The exposed workers also exhibited an increased anger-hostility, depression-dejection and fatigue-inertia on the profile of mood states (p<0.05). Performances in the Simple Reaction Time, Digit Span, Benton Visual Retention and Pursuit Aiming were also poorer among exposed workers as compared to unexposed control workers(p<0.05). Some of these poor performances in tests were also significantly related to workers’ exposure duration. P300 latencies were longer in the exposed group than in the control (p<0.05). Longer mean reaction times and more counting errors were also found in the exposed workers (p<0.05). Given the findings of our study and the limitations of neurobehavioral workplace testing, we found evidence of altered neurobehavioral outcomes by occupational exposure to vanadium. PMID:23500660

  13. Synthesis of Ti-Ta alloys with dual structure by incomplete diffusion between elemental powders.

    PubMed

    Liu, Yong; Li, Kaiyang; Wu, Hong; Song, Min; Wang, Wen; Li, Nianfeng; Tang, Huiping

    2015-11-01

    In this work, powder metallurgical (PM) Ti-Ta alloys were sintered using blended elemental powders. A dual structure, consisting of Ti-rich and Ta-rich zones, was formed due to the insufficient diffusion between Ti and Ta powders. The microstructure, mechanical properties and in vitro biological properties of the alloys were studied. Results indicated that the alloys have inhomogenous microstructures and compositions, but the grain structures were continuous from the Ti-rich zone to the Ta-rich zone. The Ta-rich zone exhibited a much finer grain size than the Ti-rich zone. The alloys had a high relative density in the range of 95-98%, with the porosity increasing with the content of Ta due to the increased difficulty in sintering and the formation of Kirkendall pores. The alloys had a good combination of low elastic modulus and high tensile strength. The strength of alloys was almost doubled compared to that of the ingot metallurgy alloys with the same compositions. The low elastic modulus was due to the residual pores and the alloying effect of Ta, while the high tensile strength resulted from the strengthening effects of solid solution, fine grain size and α phase. The alloys had a high biocompatibility due to the addition of Ta, and were suitable for the attachment of cells due to the surface porosity. It was also indicated that PM Ti-(20-30)Ta alloys are promising for biomedical applications after the evaluations of both the mechanical and the biological properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Structural study of quasi-one-dimensional vanadium pyroxene LiVSi{sub 2}O{sub 6} single crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ishii, Yuto; Matsushita, Yoshitaka; Oda, Migaku

    Single crystals of quasi-one-dimensional vanadium pyroxene LiVSi{sub 2}O{sub 6} were synthesized and the crystal structures at 293 K and 113 K were studied using X-ray diffraction experiments. We found a structural phase transition from the room-temperature crystal structure with space group C2/c to a low-temperature structure with space group P2{sub 1}/c, resulting from a rotational displacement of SiO{sub 4} tetrahedra. The temperature dependence of magnetic susceptibility shows a broad maximum around 116 K, suggesting an opening of the Haldane gap expected for one-dimensional antiferromagnets with S=1. However, an antiferromagnetic long-range order was developed below 24 K, probably caused by amore » weak inter-chain magnetic coupling in the compound. - Graphical abstract: Low temperature crystal structure of LiVSi{sub 2}O{sub 6} and an orbital arrangement within the V-O zig-zag chain along the c-axis. - Highlights: • A low temperature structure of LiVSi{sub 2}O{sub 6} was determined by single crystal X-ray diffraction measurements. • The origin of the structural transition is a rotational displacement of SiO{sub 4} tetrahedra. • The uniform orbital overlap in the V-O zigzag chain makes the system a quasi one-dimensional antiferromagnet.« less

  15. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    PubMed Central

    Alvarado-Gámez, Ana Lorena; Alonso-Lomillo, María Asunción; Domínguez-Renedo, Olga; Arcos-Martínez, María Julia

    2014-01-01

    A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 μM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water. PMID:24569772

  16. Computation material science of structural-phase transformation in casting aluminium alloys

    NASA Astrophysics Data System (ADS)

    Golod, V. M.; Dobosh, L. Yu

    2017-04-01

    Successive stages of computer simulation the formation of the casting microstructure under non-equilibrium conditions of crystallization of multicomponent aluminum alloys are presented. On the basis of computer thermodynamics and heat transfer during solidification of macroscale shaped castings are specified the boundary conditions of local heat exchange at mesoscale modeling of non-equilibrium formation the solid phase and of the component redistribution between phases during coalescence of secondary dendrite branches. Computer analysis of structural - phase transitions based on the principle of additive physico-chemical effect of the alloy components in the process of diffusional - capillary morphological evolution of the dendrite structure and the o of local dendrite heterogeneity which stochastic nature and extent are revealed under metallographic study and modeling by the Monte Carlo method. The integrated computational materials science tools at researches of alloys are focused and implemented on analysis the multiple-factor system of casting processes and prediction of casting microstructure.

  17. Communication—Sol-Gel Synthesized Magnesium Vanadium Oxide, Mg x V 2 O 5 · nH 2 O: The Role of Structural Mg 2+ on Battery Performance

    DOE PAGES

    Yin, Jiefu; Pelliccione, Christopher J.; Lee, Shu Han; ...

    2016-07-12

    Magnesium intercalated vanadium oxide xerogels, Mg 0.1V 2O 5 · 2.35H 2O and Mg 0.2V 2O 5 · 2.46H 2O were synthesized using an ion removal sol gel strategy. X-ray diffraction indicated lamellar ordering with turbostratic character. X-ray absorption spectroscopy indicated greater distortion of the vanadium-oxygen coordination environment in Mg 0.2V 2O 5 · 2.46H 2O. Elemental analysis after cycling in Li + or Mg 2+ based electrolytes revealed that the magnesium content was unchanged, indicating structural Mg 2+ are retained. Furthermore, the Mg 0.1V 2O 5 · 2.35H 2O material displayed high voltage, energy density, and discharge/charge efficiency, indicatingmore » promise as a cathode material for future magnesium based batteries.« less

  18. Structural, microstructural and thermal analysis of U-(6-x)Zr-xNb alloys (x = 0, 2, 4, 6)

    NASA Astrophysics Data System (ADS)

    Kaity, Santu; Banerjee, Joydipta; Parida, S. C.; Bhasin, Vivek

    2018-06-01

    Uranium-rich U-Zr-Nb alloy is considered as a good alternative fuel for fast reactors from the perspective of excellent dimensional stability and desired thermo-physical properties to achieve higher burnup. Detailed investigations related to the structural and microstructural characterization, thermal expansion, phase transformation, microhardness were carried out on U-6Zr, U-4Zr-2Nb, U-2Zr-4Nb and U-6Nb alloys (composition in wt%) where the total amount of alloying elements was restricted to 6 wt%. Structural, microstructural and thermal analysis studies revealed that these alloys undergo a series of transformations from high temperature bcc γ-phase to a variety of equilibrium and intermediate phases depending upon alloy composition, cooling rate and quenching. The structural analysis was carried out by Rietveld refinement. The data of U-Nb and U-Zr-Nb alloys have been highlighted and compared with binary U-Zr alloy.

  19. Study of atomic structure of liquid Hg-In alloys using ab-initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Sharma, Nalini; Thakur, Anil; Ahluwalia, P. K.

    2015-05-01

    Ab-initio molecular dynamics simulations are performed to study the structural properties of liquid Hg-In alloys. The interatomic interactions are described by ab-initio pseudopotentials given by Troullier and Martins. Five liquid Hg-In mixtures (Hg10In90, Hg30In70, Hg50In50, Hg70In30 and Hg90In10) at 299K are considered. The radial distribution function g(r) and structure factor S(q) of considered alloys are compared with respective experimental results for liquid Hg (l-Hg) and (l-In). The radial distribution function g(r) shows the presence of short range order in the systems considered. Smooth curves of Bhatia-Thornton partial structure factors factor shows the presence of liquid state in the considered alloys.

  20. Structural and electronic properties of Ga2O3-Al2O3 alloys

    NASA Astrophysics Data System (ADS)

    Peelaers, Hartwin; Varley, Joel B.; Speck, James S.; Van de Walle, Chris G.

    2018-06-01

    Ga2O3 is emerging as an important electronic material. Alloying with Al2O3 is a viable method to achieve carrier confinement, to increase the bandgap, or to modify the lattice parameters. However, the two materials have very different ground-state crystal structures (monoclinic β-gallia for Ga2O3 and corundum for Al2O3). Here, we use hybrid density functional theory calculations to assess the alloy stabilities and electronic properties of the alloys. We find that the monoclinic phase is the preferred structure for up to 71% Al incorporation, in close agreement with experimental phase diagrams, and that the ordered monoclinic AlGaO3 alloy is exceptionally stable. We also discuss bandgap bowing, lattice constants, and band offsets that can guide future synthesis and device design efforts.

  1. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

  2. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

  3. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

  4. Amorphous and Crystalline Vanadium Oxides as High-Energy and High-Power Cathodes for Three-Dimensional Thin-Film Lithium Ion Batteries.

    PubMed

    Mattelaer, Felix; Geryl, Kobe; Rampelberg, Geert; Dendooven, Jolien; Detavernier, Christophe

    2017-04-19

    Flexible wearable electronics and on-chip energy storage for wireless sensors drive rechargeable batteries toward thin-film lithium ion batteries. To enable more charge storage on a given surface, higher energy density materials are required, while faster energy storage and release can be obtained by going to thinner films. Vanadium oxides have been examined as cathodes in classical and thin-film lithium ion batteries for decades, but amorphous vanadium oxide thin films have been mostly discarded. Here, we investigate the use of atomic layer deposition, which enables electrode deposition on complex three-dimensional (3D) battery architectures, to obtain both amorphous and crystalline VO 2 and V 2 O 5 , and we evaluate their thin-film cathode performance. Very high volumetric capacities are found, alongside excellent kinetics and good cycling stability. Better kinetics and higher volumetric capacities were observed for the amorphous vanadium oxides compared to their crystalline counterparts. The conformal deposition of these vanadium oxides on silicon micropillar structures is demonstrated. This study shows the promising potential of these atomic layer deposited vanadium oxides as cathodes for 3D all-solid-state thin-film lithium ion batteries.

  5. Pore-Size-Tuned Graphene Oxide Frameworks as Ion-Selective and Protective Layers on Hydrocarbon Membranes for Vanadium Redox-Flow Batteries.

    PubMed

    Kim, Soohyun; Choi, Junghoon; Choi, Chanyong; Heo, Jiyun; Kim, Dae Woo; Lee, Jang Yong; Hong, Young Taik; Jung, Hee-Tae; Kim, Hee-Tak

    2018-05-07

    The laminated structure of graphene oxide (GO) membranes provides exceptional ion-separation properties due to the regular interlayer spacing ( d) between laminate layers. However, a larger effective pore size of the laminate immersed in water (∼11.1 Å) than the hydrated diameter of vanadium ions (>6.0 Å) prevents its use in vanadium redox-flow batteries (VRFB). In this work, we report an ion-selective graphene oxide framework (GOF) with a d tuned by cross-linking the GO nanosheets. Its effective pore size (∼5.9 Å) excludes vanadium ions by size but allows proton conduction. The GOF membrane is employed as a protective layer to address the poor chemical stability of sulfonated poly(arylene ether sulfone) (SPAES) membranes against VO 2 + in VRFB. By effectively blocking vanadium ions, the GOF/SPAES membrane exhibits vanadium-ion permeability 4.2 times lower and a durability 5 times longer than that of the pristine SPAES membrane. Moreover, the VRFB with the GOF/SPAES membrane achieves an energy efficiency of 89% at 80 mA cm -2 and a capacity retention of 88% even after 400 cycles, far exceeding results for Nafion 115 and demonstrating its practical applicability for VRFB.

  6. Li-atoms-induced structure changes of Guinier–Preston–Bagaryatsky zones in AlCuLiMg alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duan, S.Y.; Le, Z.; Chen, Z.K.

    2016-11-15

    Guinier–Preston–Bagaryatsky (GPB) zones are the well-known strengthening precipitates of AlCuMg alloys formed upon thermal ageing. Here we report that when formed in AlCuLiMg alloys the GPB zones can change significantly in morphology and structure. It is shown that though they do still consist of Al, Cu and Mg elements fundamentally, the GPB zones in AlCuLiMg alloys have a rather different structure due to a featured Li-segregation at their interfaces with the matrix and possible Li-replacement of partial Mg atoms in the structure. As such the Li-containing GPB zones often develop from one-dimensional to quasi-two-dimensional precipitates. - Highlights: • We observemore » Guinier–Preston–Bagaryatsky zone variants in AlCuLiMg alloys. • We obtain atomic-resolution images of the precipitates and model their structures. • Li-atoms play a key role in modifying the structure of these precipitate variants.« less

  7. Structure-composition-property relationships in 5xxx series aluminum alloys

    NASA Astrophysics Data System (ADS)

    Unocic, Kinga A.

    Al-Mg alloys are well suited for marine applications due to their low density, ease of fabrication, structural durability, and most notably resistance to corrosion. The purpose of this study is to investigate the effects of alloying additions, mechanical processing and heat treatments on the development of grain boundary phases that have an effect on intergranular corrosion (IGC). Cu, Zn, and Si modified compositions of AA5083 were produced that were subjected to a low and high degree of cold work and various heat treatments. ASTM G67 (NAMLT) intergranular corrosion testing and detailed microstructural characterization for various alloys was carried out. An optimal composition and processing condition that yielded the best intergranular corrosion resistant material was identified based on the ASTM G67 test screening. Further, the outstanding modified AA5083 was selected for further microstructural analysis. This particular alloy with has a magnesium level high enough to make it susceptible to intergranular corrosion is very resistant to IGC. It was found that development of the appropriate sub-structure with some Cu, Si and Zn resulted in a material very resistant to IGC. Formation of many sinks, provided by sub-boundaries, within microstructure is very beneficial since it produces a relatively uniform distribution of Mg in the grain interiors, and this can suppress sensitization of this alloy very successfully. This is a very promising rote for the production of high-strength, and corrosion resistant aluminum alloys. Additionally in this study, TEM sample preparation become very crucial step in grain boundary phase investigation. Focus Ion Beam (FIB) milling was used as a primary TEM sample preparation technique because it enables to extract the samples from desired and very specific locations without dissolving grain boundary phases as it was in conventional electropolishing method. However, other issues specifically relevant to FIB milling of aluminum alloys

  8. Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

    PubMed

    Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

    2012-08-16

    Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT.

  9. Structure-induced microalloying effect in multicomponent alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guo, Gu -Qing; Yang, Liang; Wu, Shi -Yang

    2016-04-28

    In this study, the microalloying effect on glass-forming ability (GFA) has been investigated from the structural aspect, by performing synchrotron radiation x-ray diffraction and absorption measurements coupled with simulations in the NiNbZr ternary system. We propose a new parameter which counts the fraction of the fivefold symmetries in all clusters and find it is strongly associated with the GFA. In particular, this structural parameter has the highest value in a composition where the best GFA is achieved. The present work provides an in-depth understanding of microalloying-induced high GFAs in multicomponent alloys.

  10. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, Chain T.; McKamey, Claudette G.; Tortorelli, Peter F.; David, Stan A.

    1994-01-01

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium.

  11. Superplastic forming of Al-Li alloys for lightweight, low-cost structures

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J.; Wagner, John A.

    1991-01-01

    Superplastic forming of advanced aluminum alloys is being evaluated as an approach for fabricating low-cost, light-weight, cryogenic propellant tanks. Built-up structure concepts (with inherent reduced scrap rate) are under investigation to offset the additional raw material expenses incurred by using aluminum lithium alloys. This approach to fabrication offers the potential for significant improvements in both structural efficiency and overall manufacturing costs. Superplasticity is the ability of specially processed material to sustain very large forming strains without failure at elevated temperatures under controlled deformation conditions. It was demonstrated that superplastic forming technology can be used to fabricate complex structural components in a single operation and increase structural efficiency by as much as 60 percent compared to conventional configurations in skin-stiffened structures. Details involved in the application of this technology to commercial grade superplastic aluminum lithium material are presented. Included are identification of optimum forming parameters, development of forming procedures, and assessment of final part quality in terms of cavitation volume and thickness variation.

  12. A novel process for recovery of iron, titanium, and vanadium from titanomagnetite concentrates: NaOH molten salt roasting and water leaching processes.

    PubMed

    Chen, Desheng; Zhao, Longsheng; Liu, Yahui; Qi, Tao; Wang, Jianchong; Wang, Lina

    2013-01-15

    A novel process for recovering iron, titanium, and vanadium from titanomagnetite concentrates has been developed. In the present paper, the treatment of rich titanium-vanadium slag by NaOH molten salt roasting and water leaching processes is investigated. In the NaOH molten salt roasting process, the metallic iron is oxidized into ferriferous oxide, MgTi(2)O(5) is converted to NaCl-type structure of Na(2)TiO(3), and M(3)O(5) (M=Ti, Mg, Fe) is converted to α-NaFeO(2)-type structure of NaMO(2), respectively. Roasting temperature and NaOH-slag mass ratio played a considerable role in the conversion of titanium in the rich titanium-vanadium slag during the NaOH molten salt roasting process. Roasting at 500 °C for 60 min and a 1:1 NaOH-slag mass ratio produces 96.3% titanium conversion. In the water leaching process, the Na(+) was exchanged with H(+), Na(2)TiO(3) is converted to undefined structure of H(2)TiO(3), and NaMO(2) is converted to α-NaFeO(2)-type structure of HMO(2). Under the optimal conditions, 87.3% of the sodium, 42.3% of the silicon, 43.2% of the aluminum, 22.8% of the manganese, and 96.6% of the vanadium are leached out. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  13. New polytypes of LPSO structures in an Mg-Co-Y alloy

    NASA Astrophysics Data System (ADS)

    Jin, Q. Q.; Shao, X. H.; Hu, X. B.; Peng, Z. Z.; Ma, X. L.

    2017-01-01

    The magnesium alloys containing long-period stacking ordered (LPSO) structures exhibit excellent mechanical properties. Each LPSO structure is known to contain either AB‧C‧A or AB‧C building block and feature its own stacking sequences. By atomic-scale high-angle annular dark field scanning transmission electron microscopy, we find the co-existence of AB‧C‧A and AB‧C building block in a single LPSO structure of the as-cast Mg92Co2Y6 (at.%) alloy, leading to the formation of six new polytypes of the LPSO structures determined as 29H, 51R, 60H, 72R, 102R and 192R. The lattice parameter of each LPSO structure is derived as ? and ? (n presents the number of basal layers in a unit cell). The stacking sequences and the space groups of these newly identified LPSO structures are proposed based on the electron diffraction and atomic-scale aberration-corrected high-resolution images. A random distribution of Co/Y elements in the basal planes of AB‧C‧A and AB‧C structural units is also observed and discussed.

  14. Properties of vanadium-loaded iron sorbent after alkali regeneration.

    PubMed

    Khalid, Muhammad Kamran; Leiviskä, Tiina; Tanskanen, Juha

    2017-11-01

    The aim of this research was to investigate the regeneration and reuse of a commercial granular iron sorbent (mainly goethite) when used in vanadium removal. A regeneration rate of 3 M NaOH was the highest (85%) achieved, followed by 2 M NaOH (79%) and 1 M NaOH (68%). The breakthrough curves show that the regenerated material can be reused. The BET (Brunauer-Emmett-Teller) surface area increased by 35-38% and the total pore volume increased by 123-130% as a consequence of NaOH treatment. The results indicated that sodium hydroxide could be used for the regeneration of iron sorbent although the regeneration was incomplete. This may be explained by the fact that vanadium diffusion into pores is a significant sorption mechanism in addition to complex formation with surface functional groups. As a consequence, vanadium desorbability from pores is not as effective as the regeneration of surface sites. X-ray photoelectron spectroscopy analyses confirmed a very low vanadium content on the surface of the NaOH-treated iron sorbent.

  15. Vanadium removal from LD converter slag using bacteria and fungi.

    PubMed

    Mirazimi, S M J; Abbasalipour, Z; Rashchi, F

    2015-04-15

    Removal of vanadium from Linz-Donawits (LD) converter slag was investigated by means of three different species of microbial systems: Acidithiobacillus thiooxidans (autotrophic bacteria), Pseudomonas putida (heterotrophic bacteria) and Aspergillus niger (fungi). The bioleaching process was carried out in both one-step and two-step process and the leaching efficiencies in both cases were compared. Formation of inorganic and organic acids during the leaching process caused mobilization of vanadium. In order to reduce toxic effects of the metal species on the above mentioned microorganisms, a prolonged adaptation process was performed. Both bacteria, A. thiooxidans and P. putida were able to remove more than 90% of vanadium at slag concentrations of 1-5 g L(-1) after 15 days. Also, the maximum achievable vanadium removal in the fungal system was approximately 92% at a slag concentration of 1 g L(-1) after 22 days. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Nuclear spin relaxation in Au/sup 51/V: spin dynamics of a Kondo alloy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Narath, A.; Follstaedt, D.

    1977-01-01

    The temperature dependent spin dynamics of vanadium impurities in the Kondo alloy AuV (theta/sub K/ approximately equal to 300K) have been studied by means of measurements of /sup 51/V transverse relaxation rates (T/sub 2//sup -1/) for the temperature range 1 to 260 K and vanadium concentrations of 0.2 and 0.5 at.%. Contrary to published reports, we find the quantity T/sub 2/T to increase markedly with increasing temperature. Its magnitude at 260 K (15(+-5) msec-K) exceeds the limiting low-temperature value by a factor of 10. The observed increase in T/sub 2/T indicates a large reduction in the impurity spin-correlation time, e.g.,more » tau/sub e/(theta/sub K/)/tau/sub e/(0) approximately equal to 0.2.« less

  17. Correlations of phase structure and thermal stability for Alnico 8 alloys

    NASA Astrophysics Data System (ADS)

    Zhao, J. T.; Sun, Y. L.; Liu, L.; Lee, D.; Liu, Z.; Feng, X. C.; Yan, A. R.

    2017-11-01

    The correlations of phase structure and thermal stability for Alnico 8 alloys is analyzed by three-step aging at 650 °C, 600 °C and 550 °C gradually in this paper. After three-step aging the a1 phase is a chess-like structure in transverse direction and a bamboo-like structure in longitudinal direction. Meanwhile the magnetic energy product ((BH)m) increases from 9.17 MGOe to 10.59 MGOe, and the remanence temperature coefficient a(RT-180 °C) reduces from -2.31 %%/°C to -1.25 %%/°C. The MPMS and VSM measurements indicate that three-step aging makes the a1 phase be single domain particles and dispersed distribution, which plays an important role in optimizing the thermal stability of Alnico alloys.

  18. A vanadium(IV) pyrazolate metal-organic polyhedron with permanent porosity and adsorption selectivity.

    PubMed

    Augustyniak, A W; Fandzloch, M; Domingo, M; Łakomska, I; Navarro, J A R

    2015-10-11

    A vanadium(IV) pyrazolate-based open metal-organic polyhedron of [V3(μ3-O)O(OH)2(μ4-BPD)1.5(μ-HCOO)3] (BDP = benzene-1,4-bipyrazolate) formulation gives rise to a porous crystal structure exhibiting micro and mesoporosity which is useful for selective adsorption of gases.

  19. Simulation of Structural Transformations in Heating of Alloy Steel

    NASA Astrophysics Data System (ADS)

    Kurkin, A. S.; Makarov, E. L.; Kurkin, A. B.; Rubtsov, D. E.; Rubtsov, M. E.

    2017-07-01

    Amathematical model for computer simulation of structural transformations in an alloy steel under the conditions of the thermal cycle of multipass welding is presented. The austenitic transformation under the heating and the processes of decomposition of bainite and martensite under repeated heating are considered. Amethod for determining the necessary temperature-time parameters of the model from the chemical composition of the steel is described. Published data are processed and the results used to derive regression models of the temperature ranges and parameters of transformation kinetics of alloy steels. The method developed is used in computer simulation of the process of multipass welding of pipes by the finite-element method.

  20. NASA-UVA Light Aerospace Alloy and Structures Technology Program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edgar A., Jr.; Kelly, Robert G.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1997-01-01

    The NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Here, we report on progress achieved between July I and December 31, 1996. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies. The accomplishments presented in this report are summarized as follows. Three research areas are being actively investigated, including: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals, (2) Aerospace Materials Science, and (3) Mechanics of Materials for Light Aerospace Structures.

  1. Phosphovanadylite: a new vanadium phosphate mineral with a zeolite-type structure

    USGS Publications Warehouse

    Medrano, M.D.; Evans, H.T.; Wenk, H.-R.; Piper, D.Z.

    1998-01-01

    Phosphovanadylite, whose simplified formula is (Ba,Ca,K,Na)x([(Va,Al)4P2(P,OH)16].12H2), is a new vanadium phosphate zeolite mineral found in the Phosphoria Formation at Monsanto's Enoch Valley Mine, Soda Springs, Idaho. Its formula in more detail is (Ba0.38Ca0.20K0.006Na0.02)??0.66 [P2(V3.44Al0.046)??3.90O10.34(OH)5.66] .12H2O. The drusy mineral occurs as pale greenish-blue euhedral cubes (20-50 ??m edge) coating phosphatic, organic-rich mudstone. The chemical composition determined by electron microprobe is (in weight percent) V-28.02, P-9.91, Al-1.97, Ca-1.31, Ba-8.28, Cd-0.09, Zn-0.34, Na-0.15, K-0.73, O-46.57, and F-0.03. The index of refraction is nD = 1.566 (4) and specific gravity is 2.16 (3). The X-ray powder pattern shows strong reflections at 3.16 A (422), 2.58 (600), 2.44 (620), and 7.73 (200), which are indexed on the basis of a cubic body-centered unit cell with a = 15.470 (4) A. From the single-crystal structure analysis, its space group was determined to be I43m, Z = 6, and its structure consists of V4O18 16 octahedral clusters linked to each other by P atoms to form a cubic lattice, creating cavities 7.0 and 5.5 A in diameter where mainly H2O resides. Final residual indexes are R = 0.066, Rw = 0.061, goodness-of-fit = 0.75, and 93 observations and 24 parameters.

  2. Low void content autoclave molded titanium alloy and polyimide graphite composite structures.

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J.; Creedon, J. F.

    1972-01-01

    This paper discusses a resin developed for use in autoclave molding of polyimide graphite composite stiffened, titanium alloy structures. Both primary and secondary bonded structures were evaluated that were produced by autoclave processing. Details of composite processing, adhesive formulary, and bonding processes are provided in this paper, together with mechanical property data for structures. These data include -65 F, room temperature, and 600 F shear strengths; strength retention after aging; and stress rupture properties at 600 F under various stress levels for up to 1000 hours duration. Typically, shear strengths in excess of 16 ksi at room temperature with over 60% strength retention at 600 F were obtained with titanium alloy substrates.

  3. Synthesis by sol-gel process, structural and optical properties of nanoparticles of zinc oxide doped vanadium

    NASA Astrophysics Data System (ADS)

    El Ghoul, J.; Barthou, C.; El Mir, L.

    2012-06-01

    We report the elaboration of vanadium-doped ZnO nanoparticles prepared by a sol-gel processing technique. In our approach, the water for hydrolysis was slowly released by esterification reaction followed by a supercritical drying in ethyl alcohol. Vanadium doping concentration of 10 at.% has been investigated. After treatment in air at different temperatures, the obtained nanopowder was characterised by various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence (PL). Analysis by scanning electron microscopy at high resolution shows that the grain size increases with increasing temperature. Thus, in the case of thermal treatment at 500 °C in air, the powder with an average particle size of 25 nm shows a strong luminescence band in the visible range. The intensity and energy position of the obtained PL band depends on the temperature measurement increase. The mechanism of this emission band is discussed.

  4. Vanadium doped tin dioxide as a novel sulfur dioxide sensor.

    PubMed

    Das, S; Chakraborty, S; Parkash, O; Kumar, D; Bandyopadhyay, S; Samudrala, S K; Sen, A; Maiti, H S

    2008-04-15

    Considering the short-term exposure limit of SO2 to be 5 ppm, we first time report that semiconductor sensors based on vanadium doped SnO2 can be used for SO2 leak detection because of their good sensitivity towards SO2 at concentrations down to 5 ppm. Such sensors are quite selective in presence of other gases like carbon monoxide, methane and butane. The high sensitivity of vanadium doped tin dioxide towards SO2 may be understood by considering the oxidation of sulfur dioxide to sulfur trioxide on SnO2 surface through redox cycles of vanadium-sulfur-oxygen adsorbed species.

  5. Activation characteristics of multiphase Zr-based hydrogen storage alloys for Ni/MH rechargeable batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, H.; Lee, S.M.; Lee, J.Y.

    1999-10-01

    AB{sub 2} type Zr-based Laves phase alloys have been studied for possible use as negative electrodes of Ni/MH batteries with high hydrogen storage capacity. However, these alloys have the serious problem of slow activation owing to the formation of surface oxide films. To overcome this problem, alloys with multiphase microstructures have been developed. These alloys become electrochemically active via the creation of micropores by the dissolution of soluble oxide components such as vanadium oxide. However, this phenomenon has been described based only on changes in the chemical composition of the oxide layer. In the present study, this phenomenon is approachedmore » with respect to interactions between the constituent phases. An electrochemical analysis of constituent phases showed that the second phase, resulting in localized Ni-rich pits on the alloy surface. The presence of microcracks at the periphery of the Ni-rich pits after 30 h exposure to KOH electrolyte implies that hydrogen is absorbed preferentially at Ni-rich pits, thereby forming a large active surface area. However, such multiphase alloys have poor cycle durability due to the persistent dissolution of components in the second phase. Through Cr substitution, the authors have developed a family of durable alloys to prevent this unwanted dissolution from the second phase.« less

  6. Process optimization for diffusion bonding of tungsten with EUROFER97 using a vanadium interlayer

    NASA Astrophysics Data System (ADS)

    Basuki, Widodo Widjaja; Aktaa, Jarir

    2015-04-01

    Solid-state diffusion bonding is a selected joining technology to bond divertor components consisting of tungsten and EUROFER97 for application in fusion power plants. Due to the large mismatch in their coefficient of thermal expansions, which leads to serious thermally induced residual stresses after bonding, a thin vanadium plate is introduced as an interlayer. However, the diffusion of carbon originated from EUROFER97 in the vanadium interlayer during the bonding process can form a vanadium carbide layer, which has detrimental influences on the mechanical properties of the joint. For optimal bonding results, the thickness of this layer and the residual stresses has to be decreased sufficiently without a significant reduction of material transport especially at the vanadium/tungsten interface, which can be achieved by varying the diffusion bonding temperature and duration. The investigation results show that at a sufficiently low bonding temperature of 700 °C and a bonding duration of 4 h, the joint reaches a reasonable high ductility and toughness especially at elevated test temperature of 550 °C with elongation to fracture of 20% and mean absorbed Charpy impact energy of 2 J (using miniaturized Charpy impact specimens). The strength of the bonded materials is about 332 MPa at RT and 291 MPa at 550 °C. Furthermore, a low bonding temperature of 700 °C can also help to avoid the grain coarsening and the alteration of the grain structure especially of the EUROFER97 close to the bond interface.

  7. 4-d magnetism: Electronic structure and magnetism of some Mo-based alloys

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Bose, S. K.; Kudrnovský, J.

    2017-02-01

    We report results of a first-principles density-functional study of alloys of the 4 d -element Mo with group IV elements Si, Ge and Sn in zinc blende (ZB) and rock salt (RS) structures. The study was motivated by a similar study of ours based on the 4 d -element Tc, which showed the presence of half-metallic states with integer magnetic moment (1μB) per formula unit in TcX (X=C, Si, Ge) alloys. The calculated Curie temperatures for the ferromagnetic (FM) phases were low, around or less than 300 K. Searching for the possibility of 4 d -based alloys with higher Curie temperatures we have carried out the study involving the elements Mo, Ru and Rh. Among these the most promising case appears to be that involving the element Mo. Among the MoX (X=Si, Ge, Sn) alloys in ZB and RS structures, both MoGe and MoSn in ZB structures are found to possess an integer magnetic moment of 2μB per formula unit. ZB MoSn can be classified as a marginal/weak half-metal or a spin gapless semiconductor, while ZB MoGe would be best described as a gapless magnetic semiconductor. The calculated Curie temperatures are in the range 300-700 K. Considering the theoretical uncertainty in the band gaps due not only to the treatment of exchange and correlation effects, but density functional theory itself, these classifications may change somewhat, but both merit investigation from the viewpoint of potential spintronic application. Based on their higher Curie temperatures, Mo-based alloys would serve such purpose better than the previously reported Tc-based ones.

  8. Quantitative LIBS analysis of vanadium in samples of hexagonal mesoporous silica catalysts.

    PubMed

    Pouzar, Miloslav; Kratochvíl, Tomás; Capek, Libor; Smoláková, Lucie; Cernohorský, Tomás; Krejcová, Anna; Hromádko, Ludek

    2011-02-15

    The method for the analysis of vanadium in hexagonal mesoporous silica (V-HMS) catalysts using Laser Induced Breakdown Spectrometry (LIBS) was suggested. Commercially available LIBS spectrometer was calibrated with the aid of authentic V-HMS samples previously analyzed by ICP OES after microwave digestion. Deposition of the sample on the surface of adhesive tape was adopted as a sample preparation method. Strong matrix effect connected with the catalyst preparation technique (1st vanadium added in the process of HMS synthesis, 2nd already synthesised silica matrix was impregnated by vanadium) was observed. The concentration range of V in the set of nine calibration standards was 1.3-4.5% (w/w). Limit of detection was 0.13% (w/w) and it was calculated as a triple standard deviation from five replicated determinations of vanadium in the real sample with a very low vanadium concentration. Comparable results of LIBS and ED XRF were obtained if the same set of standards was used for calibration of both methods and vanadium was measured in the same type of real samples. LIBS calibration constructed using V-HMS-impregnated samples failed for measuring of V-HMS-synthesized samples. LIBS measurements seem to be strongly influenced with different chemical forms of vanadium in impregnated and synthesised samples. The combination of LIBS and ED XRF is able to provide new information about measured samples (in our case for example about procedure of catalyst preparation). Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Dendritic growth and structure of undercooled nickel base alloys

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Shiohara, Y.

    1988-01-01

    The principal objectives of this overall investigation are to: study means for obtaining high undercooling in levitation melted droplets, and study structures produced upon the solidification of these undercooled specimens. Thermal measurements are made of the undercooling, and of the rapid recalescence, to develop an understanding of the solidification mechanism. Comparison of results is made with the modeling studies. Characterization and metallographic work is done to gain an understanding of the relationship between rapid solidification variables and the structures so produced. In ground based work to date, solidification of undercooled Ni-25 wt percent Sn alloy was observed by high-speed cinematography and the results compared with optical temperature measurements. Also in ground based work, high-speed optical temperature measurements were made of the solidification behavior of levitated metal samples within a transparent glass medium. Two undercooled Ni-Sn alloys were examined. Measurements were carried out on samples at undercoolings up to 330 K. Microstructures of samples produced in ground based work were determined by optical metallography and by SEM, and microsegregation by electron microprobe measurements. A series of flight tests were planned to conduct experiments similar to the ground based experiments. The Space Shuttle Columbia carried an alloy undercooled experiment in the STS 61-C mission in January 1986. A sample of Ni-32.5 wt percent Sn eutectic was melted and solidified under microgravity conditions.

  10. Effect of diet composition on vanadium toxicity for the chick

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berg, L.R.

    1966-01-01

    Studies to determine the effect of diet composition on the toxicity of 20 ppm added vanadium for the young chick have shown: growth depression of 25-30% with a corn-soybean meal ration but only 3-7% with a corn-herring fish meal diet. Growth depression of 35-40% with a semi-purified sucrose-soybean meal diet and approximately 50% with a diet of sucrose and herring fish meal. Adding graded levels of corn to the sucrose-fish meal ration and fish meal to the corn-soybean meal ration reduced vanadium toxicity. The corn fractions, ash, oil, starch, zein and gluten did not reduce vanadium toxicity. Removing the addedmore » magnesium (300 ppm) and potassium (2000 ppm) from the sucrose-fish meal ration did not affect growth rate or mortality. However removal of these materials from the basal ration increased growth depression due to added vanadium from 43-56% and increased mortality from 10-80%. 4 references, 9 tables.« less

  11. Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gubbi, A.N.; Rowcliffe, A.F.; Lee, E.H.

    1996-10-01

    Automated Ball Indentation (ABI) testing, was successfully employed to determine the flow properties of the fusion zone, heat affected zone (HAZ), and base metal of the gas tungsten arc (GTA) and electron beam (EB) welds of the V-4Cr-4Ti (large heat no. 832665) and the V-5Cr-5Ti (heat 832394) alloys. ABI test results showed a clear distinction among the properties of the fusion zone, HAZ, and base metal in both GTA and EB welds of the two alloys. GTA and EB welds of both V-4Cr-4Ti and V-5Cr-5Ti alloys show strengthening of both the fusion zone and the HAZ (compared to base metal)more » with the fusion zone having higher strength than the HAZ. These data correlate well with the Brinell hardness. On the other hand, GTA welds of both alloys, after a post-weld heat treatment of 950{degrees}C for 2 h, show a recovery of the properties to base metal values with V-5Cr-5Ti showing a higher degree of recovery compared to V-4Cr-4Ti. These measurements correlate with the reported recovery of the Charpy impact properties.« less

  12. Efficacy of Tantalum Tungsten Alloys for Diffusion Barrier Applications

    NASA Astrophysics Data System (ADS)

    Smathers, D. B.; Aimone, P. R.

    2017-12-01

    Traditionally either Niobium, Tantalum or a combination of both have been used as diffusion barriers in Nb3Sn Multi-filament wire. Vanadium has also been used successfully but the ultimate RRR of the copper is limited unless an external shell of Niobium is included. Niobium is preferred over Tantalum when alternating current losses are not an issue as the Niobium will react to form Nb3Sn. Pure Tantalum tends to deform irregularly requiring extra starting thickness to ensure good barrier qualities. Our evaluations showed Tantalum lightly alloyed with 3 wt% Tungsten is compatible with the wire drawing process while deforming as well as or better than pure Niobium. Ta3wt%W has been processed as a single barrier and as a distributed barrier to fine dimensions. In addition, the higher modulus and strength of the Tantalum Tungsten alloy improves the overall tensile properties of the wire.

  13. Method of producing superplastic alloys and superplastic alloys produced by the method

    NASA Technical Reports Server (NTRS)

    Troeger, Lillianne P. (Inventor); Starke, Jr., Edgar A. (Inventor); Crooks, Roy (Inventor)

    2002-01-01

    A method for producing new superplastic alloys by inducing in an alloy the formation of precipitates having a sufficient size and homogeneous distribution that a sufficiently refined grain structure to produce superplasticity is obtained after subsequent PSN processing. An age-hardenable alloy having at least one dispersoid phase is selected for processing. The alloy is solution heat-treated and cooled to form a supersaturated solid solution. The alloy is plastically deformed sufficiently to form a high-energy defect structure useful for the subsequent heterogeneous nucleation of precipitates. The alloy is then aged, preferably by a multi-stage low and high temperature process, and precipitates are formed at the defect sites. The alloy then is subjected to a PSN process comprising plastically deforming the alloy to provide sufficient strain energy in the alloy to ensure recrystallization, and statically recrystallizing the alloy. A grain structure exhibiting new, fine, equiaxed and uniform grains is produced in the alloy. An exemplary 6xxx alloy of the type capable of being produced by the present invention, and which is useful for aerospace, automotive and other applications, is disclosed and claimed. The process is also suitable for processing any age-hardenable aluminum or other alloy.

  14. Simulated Single Tooth Bending of High Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert, F.; Burke, Christopher

    2012-01-01

    Future unmanned space missions will require mechanisms to operate at extreme conditions in order to be successful. In some of these mechanisms, very high gear reductions will be needed to permit very small motors to drive other components at low rotational speed with high output torque. Therefore gearing components are required that can meet the mission requirements. In mechanisms such as this, bending fatigue strength capacity of the gears is very important. The bending fatigue capacity of a high temperature, nickel-based alloy, typically used for turbine disks in gas turbine engines and two tool steel materials with high vanadium content, were compared to that of a typical aerospace alloy-AISI 9310. Test specimens were fabricated by electro-discharge machining without post machining processing. Tests were run at 24 and at 490 C. As test temperature increased from 24 to 490 C the bending fatigue strength was reduced by a factor of five.

  15. Change In The Electronic Structure And Optical Absorption Of Cuprate Delafossites Via B-site Alloying

    NASA Astrophysics Data System (ADS)

    Beesley, Ramon; Panapitiya, Gihan; Lewis, James; Lewis Group Team

    Delafossite oxides are a family of materials with the form ABO2 , where the A-site is a monovalent cation (Cu , Ag , Au) and the B-site is a trivalent cation (Ga , Al , In). Delafossites typically have a wide optical band gap, this band gap may be tuned by adding a second B-site element forming an AB(1- x) 1B(x)2O2 alloy. We investigate changes in the electronic structure of CuAlO2 , CuGaO2 , and CuInO2 when alloyed with CuFeO2 . Using the FIREBALL program to optimize the atomic structure, calculate the total and partial density of states, calculate the valence band edge for each alloy level, and investigate the clustering factor of the second B-site atom, it is found that alloying with Fe creates midgap states caused by Fe - O interactions. From the partial density of state, each type of atoms contribution to the change in the valence band edge can be seen. Observed changes to the materials include increased optical absorption in the visible range, and symmetry breaking because of the deformation in the crystal structure. The CuFeO2 alloying percentages range from 0-5%. We are synthesizing these alloys to experimentally verify the changes in the optical absorption spectra.

  16. Transport, Structural and Mechanical Properties of Quaternary FeVTiAl Alloy

    NASA Astrophysics Data System (ADS)

    Bhat, Tahir Mohiuddin; Gupta, Dinesh C.

    2016-11-01

    The electronic, structural, magnetic and transport properties of FeVTiAl quaternary alloy have been investigated within the framework of density functional theory. The material is a completely spin-polarized half-metallic ferromagnet in its ground state with F-43m structure. The structural stability was further confirmed by elastic constants in the cubic phase with high Young's modulus and brittle nature. The present study predicts an energy band gap of 0.72 eV in a localized minority spin channel at equilibrium lattice parameter of 6.00 Å. The transport properties of the material are discussed based on the Seebeck coefficient, and electrical and thermal conductivity coefficients. The alloy presents large values of Seebeck coefficients, ~39 μV K-1 at room temperature (300 K), and has an excellent thermoelectric performance with ZT = ~0.8.

  17. Development of Creep-Resistant, Alumina-Forming Ferrous Alloys for High-Temperature Structural Use

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yamamoto, Yukinori; Brady, Michael P.; Muralidharan, Govindarajan

    This paper overviews recent advances in developing novel alloy design concepts of creep-resistant, alumina-forming Fe-base alloys, including both ferritic and austenitic steels, for high-temperature structural applications in fossil-fired power generation systems. Protective, external alumina-scales offer improved oxidation resistance compared to chromia-scales in steam-containing environments at elevated temperatures. Alloy design utilizes computational thermodynamic tools with compositional guidelines based on experimental results accumulated in the last decade, along with design and control of the second-phase precipitates to maximize high-temperature strengths. The alloys developed to date, including ferritic (Fe-Cr-Al-Nb-W base) and austenitic (Fe-Cr-Ni-Al-Nb base) alloys, successfully incorporated the balanced properties of steam/water vapor-oxidationmore » and/or ash-corrosion resistance and improved creep strength. Development of cast alumina-forming austenitic (AFA) stainless steel alloys is also in progress with successful improvement of higher temperature capability targeting up to ~1100°C. Current alloy design approach and developmental efforts with guidance of computational tools were found to be beneficial for further development of the new heat resistant steel alloys for various extreme environments.« less

  18. Tensile and impact properties of General Atomics 832864 heat of V-4Cr-4Ti alloy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tsai, H.; Nowicki, L.J.; Gazda, J.

    A 1300-kg heat of V-4Cr-4Ti alloy was procured by General Atomics (GA) for the DIII-D radiative divertor program. To determine the mechanical properties of this alloy, tensile and Charpy tests were conducted on specimens prepared from pieces of 4.8-mm-thick as-rolled plates, a major product form for the DIII-D application. The tensile tests were conducted at three temperatures, 26, 280 and 380 C, the last two being the anticipated peak temperatures during DIII-D boronization and postvent bake-out, respectively. Results from these tests show that the tensile and impact properties of the 832864 heat are comparable to those of the other smallermore » V-(4-5)Cr-(4-5)Ti alloy heats previously developed by the US Fusion Materials Program and that scale-up of vanadium alloy production can be successfully achieved as long as reasonable process control is implemented.« less

  19. Ab Initio Calculations of Transport Properties of Vanadium Oxides

    NASA Astrophysics Data System (ADS)

    Lamsal, Chiranjivi; Ravindra, N. M.

    2018-04-01

    The temperature-dependent transport properties of vanadium oxides have been studied near the Fermi energy using the Kohn-Sham band structure approach combined with Boltzmann transport equations. V2O5 exhibits significant thermoelectric properties, which can be attributed to its layered structure and stability. Highly anisotropic electrical conduction in V2O5 is clearly manifested in the calculations. Due to specific details of the band structure and anisotropic electron-phonon interactions, maxima and crossovers are also seen in the temperature-dependent Seebeck coefficient of V2O5. During the phase transition of VO2, the Seebeck coefficient changes by 18.9 µV/K, which is close to (within 10% of) the observed discontinuity of 17.3 µV/K.

  20. Microstructural and microchemical studies of phase stability in V-O solid solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ghosh, Chanchal, E-mail: chanchal@igcar.gov.in

    2017-02-15

    Over the last couple of decades vanadium and V-based alloys have received significant attention as a potential structural material for fusion power applications because of their favourable mechanical properties under irradiation and at elevated temperatures. They are also considered as the advanced options of storage materials for hydrogen and its isotopes. However, the higher affinity of V for O, C and N poses critical challenges in its engineering applications since they lead to degradation of mechanical properties. They can further interact with the matrix to produce metallic oxy-carbo-nitride precipitates. To a certain limit, these precipitates are beneficial and can bemore » exploited to enhance the mechanical behaviour of the alloy through suitable microstructural design. However, this requires a prior knowledge of the interaction between the alloy and the impurity solutes. In the present work vanadium specific experiments have been designed and carried out to bring out the V-interstitial solute interaction by charging oxygen in the near surface region of vanadium. Microstructural and microchemical behaviour of the V-O solid solution has been studied through HRTEM (high resolution transmission electron microscopy) and HAADF (high angle annular dark field) coupled with EELS. Quantitative electron microscopy has been carried out to study structural modification of the alloy in atomic level caused by O charging. - Highlights: •Controlled experiments were carried out in pulsed laser ablation set-up to promote V-O interaction. • As a consequence of O dissolution, V transformed into a bct structure which is otherwise a bcc structure. •In V-O solid solution, dissolved O in the V matrix introduces significant amount of lattice strain. • Present work can be extended for introducing interstitial O in other pure transition metals and their alloys.« less

  1. Rate Dependency of Silver Vanadium Phosphorous Oxide Reduction

    NASA Astrophysics Data System (ADS)

    Cheng, Po-Jen

    2011-12-01

    The silver vanadium phosphorus oxide (Ag2VO2PO 4) is a high-capacity and good-compatibility material for the cathode in the battery. Due to their innovative properties, they are used as cathode in lithium batteries. Therefore, when the lithium batteries begin to discharge, the anodes of the cell perform an electrochemical oxidation and release electrons. In the mean time, the cathodes in the cells perform the electrochemical reduction and catch the electrons. For reduction of Ag2VO2PO 4, two silver ions (Ag+) catch two electrons to form silver particles, and the vanadium ions (V5+) catch two electrons to form V3+. It means that four electrons will be released by lithium anode. We call this four electrons discharge as 100% discharge. In my most of the projects, the Ag2VO2PO4 material is tested by differential scanning calorimetry (DSC) to check purity. My study is based on the discharge of batteries, and I focus on the morphology and the intensity of silver particles on the cathode after discharge. Depending on different adjustment of factors, such as discharge time, discharge rate, storage time, storage temperature, I try to investigate the silver intensity, conductivity as a function of DOD (Depth of Discharge). The silver particles could be examined by optical microscope, and scanning electron microscope (SEM). Moreover, I do some x-ray diffraction analysis to quantify the silver particles after discharge. Also, I perform magnetic susceptibility measurement to check the mechanism of the reduction of vanadium ions. Under the research on silver ions and vanadium ions, I will know a big frame of reduction process on silver vanadium phosphorous oxide and the time effect on this cathode material.

  2. Study of atomic structure of liquid Hg-In alloys using ab-initio molecular dynamics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sharma, Nalini; Ahluwalia, P. K.; Thakur, Anil

    2015-05-15

    Ab-initio molecular dynamics simulations are performed to study the structural properties of liquid Hg-In alloys. The interatomic interactions are described by ab-initio pseudopotentials given by Troullier and Martins. Five liquid Hg-In mixtures (Hg{sub 10}In{sub 90}, Hg{sub 30}In{sub 70}, Hg{sub 50}In{sub 50}, Hg{sub 70}In{sub 30} and Hg{sub 90}In{sub 10}) at 299K are considered. The radial distribution function g(r) and structure factor S(q) of considered alloys are compared with respective experimental results for liquid Hg (l-Hg) and (l-In). The radial distribution function g(r) shows the presence of short range order in the systems considered. Smooth curves of Bhatia-Thornton partial structure factors factormore » shows the presence of liquid state in the considered alloys.« less

  3. Structure and phase composition of ultrafine-grained TiNb alloy after high-temperature annealings

    NASA Astrophysics Data System (ADS)

    Eroshenko, Anna Yu.; Glukhov, Ivan A.; Mairambekova, Aikol; Tolmachev, Alexey I.; Sharkeev, Yurii P.

    2017-12-01

    The paper presents the experimental data observed in the microstructure and phase composition of ultrafine-grained Ti-40 mass % Nb (Ti40Nb) alloy after high-temperature annealings. The ultrafine-grained Ti40Nb alloy is produced by severe plastic deformation (SPD). This method includes multiple abc-pressing and multi-pass rolling followed by further pre-recrystallizing annealing which, in its turn, enhances the formation of ultrafine-grained structures with mean size of 0.28 µm involving stable β- and α-phase and metastable nanosized ω-phase in the alloy. It is shown that annealing at 500°C preserves the ultrafine-grained structure and phase composition. In cases of annealing at 800°C the ultrafine-grained state transforms into the coarse-grained state. The stable β-phase and the nanosized metastable ω-phase have been identified in the coarse-grained structure.

  4. Corrosion resistant iron aluminides exhibiting improved mechanical properties and corrosion resistance

    DOEpatents

    Liu, C.T.; McKamey, C.G.; Tortorelli, P.F.; David, S.A.

    1994-06-14

    The specification discloses a corrosion-resistant intermetallic alloy comprising, in atomic percent, an FeAl iron aluminide containing from about 30 to about 40% aluminum alloyed with from about 0.01 to 0.4% zirconium and from 0.01 to about 0.8% boron. The alloy exhibits considerably improved room temperature ductility for enhanced usefulness in structural applications. The high temperature strength and fabricability is improved by alloying with molybdenum, carbon, chromium and vanadium. 9 figs.

  5. Neurotoxicity of Vanadium.

    PubMed

    Ngwa, Hilary Afeseh; Ay, Muhammet; Jin, Huajun; Anantharam, Vellareddy; Kanthasamy, Arthi; Kanthasamy, Anumantha G

    2017-01-01

    Vanadium (V) is a transition metal that presents in multiple oxidation states and numerous inorganic compounds and is also an ultra-trace element considered to be essential for most living organisms. Despite being one of the lightest metals, V offers high structural strength and good corrosion resistance and thus has been widely adopted for high-strength steel manufacturing. High doses of V exposure are toxic, and inhalation exposure to V adversely affects the respiratory system. The neurotoxicological properties of V are just beginning to be identified. Recent studies by our group and others demonstrate the neurotoxic potential of this metal in the nigrostriatal system and other parts of the central nervous system (CNS). The neurotoxic effects of V have been mainly attributed to its ability to induce the generation of reactive oxygen species (ROS). It is noteworthy that the neurotoxicity induced by occupational V exposure commonly occurs with co-exposure to other metals, especially manganese (Mn). This review focuses on the chemistry, pharmacology, toxicology, and neurotoxicity of V.

  6. Influence of heat treatment and oxygen doping on the mechanical properties and biocompatibility of titanium-niobium binary alloys.

    PubMed

    da Silva, Luciano Monteiro; Claro, Ana Paula Rosifini Alves; Donato, Tatiani Ayako Goto; Arana-Chavez, Victor E; Moraes, João Carlos Silos; Buzalaf, Marília Afonso Rabelo; Grandini, Carlos Roberto

    2011-05-01

    The most commonly used titanium (Ti)-based alloy for biological applications is Ti-6Al-4V, but some studies associate the vanadium (V) with the cytotoxic effects and adverse reactions in tissues, while aluminum (Al) has been associated with neurological disorders. Ti-Nb alloys belong to a new class of Ti-based alloys with no presence of Al and V and with elasticity modulus values that are very attractive for use as a biomaterial. It is well known that the presence of interstitial elements (such as oxygen, for example) changes the mechanical properties of alloys significantly, particularly the elastic properties, the same way that heat treatments can change the microstructure of these alloys. This article presents the effect of heat treatment and oxygen doping in some mechanical properties and the biocompatibility of three alloys of the Ti-Nb system, characterized by density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, in vitro cytotoxicity, and mechanical spectroscopy. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  7. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... uranium, radium and vanadium ores subcategory. 440.30 Section 440.30 Protection of Environment... SOURCE CATEGORY Uranium, Radium and Vanadium Ores Subcategory § 440.30 Applicability; description of the uranium, radium and vanadium ores subcategory. The provisions of this subpart C are applicable to...

  8. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Madiba, I. G.; Émond, N.; Chaker, M.; Thema, F. T.; Tadadjeu, S. I.; Muller, U.; Zolliker, P.; Braun, A.; Kotsedi, L.; Maaza, M.

    2017-07-01

    Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO2) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO2 phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO2 structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V-V inter-dimer distance, which in turns favours the presence of the VO2 metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V4+ towards V5+ is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the valence band. Our observations suggest that gamma radiations induce the formation of Frenkel pairs. Moreover, THz transmission measurements show that the long range structure of VO2 remains intact after irradiation whilst the electrical measurements evidence that the coating resistivity decreases with gamma irradiation and that their transition temperature is slightly reduced for high gamma ray doses. Even though gamma rays are only one of the sources of radiations that are encountered in space environment, these results are very promising with regards to the potential of integration of such VO2 films as a protective coating for spacecrafts.

  9. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.

    1992-01-01

    The NASA-UVa Light Aerospace Alloy and Structure Technology (LAST) Program continues to maintain a high level of activity, with projects being conducted by graduate students and faculty advisors in the Departments of Materials Science and Engineering, Civil Engineering and Applied Mechanics, and Mechanical and Aerospace Engineering at the University of Virginia. This work is funded by the NASA-Langley Research Center under Grant NAG-1-745. Here, we report on progress achieved between January 1 and June 30, 1992. The objectives of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of the next generation, light weight aerospace alloys, composites and thermal gradient structures in collaboration with Langley researchers. Technical objectives are established for each research project. We aim to produce relevant data and basic understanding of material mechanical response, corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement advances; and critically, a pool of educated graduate students for aerospace technologies. The accomplishments presented in this report cover topics including: (1) Mechanical and Environmental Degradation Mechanisms in Advance Light Metals and Composites; (2) Aerospace Materials Science; (3) Mechanics of Materials and Composites for Aerospace Structures; and (4) Thermal Gradient Structures.

  10. Hydrogen Production by Steam Reforming of Natural Gas Over Vanadium-Nickel-Alumina Catalysts.

    PubMed

    Yoo, Jaekyeong; Park, Seungwon; Song, Ji Hwan; Song, In Kyu

    2018-09-01

    A series of vanadium-nickel-alumina (xVNA) catalysts were prepared by a single-step sol-gel method with a variation of vanadium content (x, wt%) for use in the hydrogen production by steam reforming of natural gas. The effect of vanadium content on the physicochemical properties and catalytic activities of xVNA catalysts in the steam reforming of natural gas was investigated. It was found that natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium content. It was also revealed that natural gas conversion and hydrogen yield increased with decreasing nickel crystallite size.

  11. Interacting quasi-band model for electronic states in compound semiconductor alloys: Zincblende structure

    NASA Astrophysics Data System (ADS)

    Shinozuka, Yuzo; Oda, Masato

    2015-09-01

    The interacting quasi-band model proposed for electronic states in simple alloys is extended for compound semiconductor alloys with general lattice structures containing several atoms per unit cell. Using a tight-binding model, a variational electronic wave function for quasi-Bloch states yields a non-Hermitian Hamiltonian matrix characterized by matrix elements of constituent crystals and concentration of constituents. Solving secular equations for each k-state yields the alloy’s energy spectrum for any type of randomness and arbitrary concentration. The theory is used to address III-V (II-VI) alloys with a zincblende lattice with crystal band structures well represented by the sp3s* model. Using the resulting 15 × 15 matrix, the concentration dependence of valence and conduction bands is calculated in a unified scheme for typical alloys: Al1-xGaxAs, GaAs1-xPx, and GaSb1-xPx. Results agree well with experiments and are discussed with respect to the concentration dependence, direct-indirect gap transition, and band-gap-bowing origin.

  12. Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

    NASA Astrophysics Data System (ADS)

    Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

    2016-02-01

    In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

  13. The (oxo)[(2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(4-tolylporphyrinato)]vanadium(IV): Synthesis, UV-visible, Cyclic voltammetry and X-ray crystal structure

    NASA Astrophysics Data System (ADS)

    Mchiri, Chadlia; Amiri, Nesrine; Jabli, Souhir; Roisnel, Thierry; Nasri, Habib

    2018-02-01

    The present work is concerned with the oxo vanadium(IV) complex of 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(4-tolylporphyrin) with formula [V(Cl8TTP)O] (I), which was prepared by reacting the (oxo)[5,10,15,20-tetrakis(4-tolylporphyrinato)]vanadium(IV) complex ([V(TTP)O]), under aerobic atmosphere, with a large excess of thionyl chloride (SOCl2). The title compound was characterized by UV-visible spectroscopy, cyclic voltammetry and X-ray crystal structure. The electron-withdrawing chlorine substituents at the pyrrole carbons in the vanadyl-Cl8TTP derivative produce remarkable redshifts of the Soret and Q absorption bands and an important anodic shift of the porphyrin ring oxidation and reduction potentials. This is an indication that the porphyrin core of complex (I) is severely nonplanar in solution. The molecular structure of our vanadyl derivative shows a very high saddle distortion and an important ruffled deformation of the porphyrin macrocycle. The crystal structure of (I) is made by one-dimensional chains parallel to the c axis where channels are located between these chains.

  14. Tuning structural motifs and alloying of bulk immiscible Mo-Cu bimetallic nanoparticles by gas-phase synthesis

    NASA Astrophysics Data System (ADS)

    Krishnan, Gopi; Verheijen, Marcel A.; Ten Brink, Gert H.; Palasantzas, George; Kooi, Bart J.

    2013-05-01

    Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still remains a formidable challenge. Hence, we present here a general methodology for gas phase synthesis of bimetallic NPs with distinctively different structural motifs ranging at a single particle level from a fully mixed alloy to core-shell, to onion (multi-shell), and finally to a Janus/dumbbell, with the same overall particle composition. These concepts are illustrated for Mo-Cu NPs, where the precise control of the bimetallic NPs with various degrees of chemical ordering, including different shapes from spherical to cube, is achieved by tailoring the energy and thermal environment that the NPs experience during their production. The initial state of NP growth, either in the liquid or in the solid state phase, has important implications for the different structural motifs and shapes of synthesized NPs. Finally we demonstrate that we are able to tune the alloying regime, for the otherwise bulk immiscible Mo-Cu, by achieving an increase of the critical size, below which alloying occurs, closely up to an order of magnitude. It is discovered that the critical size of the NP alloy is not only affected by controlled tuning of the alloying temperature but also by the particle shape.Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still

  15. Protective effect of alpha glucosyl hesperidin (G-hesperidin) on chronic vanadium induced testicular toxicity and sperm nuclear DNA damage in male Sprague Dawley rats.

    PubMed

    Vijaya Bharathi, B; Jaya Prakash, G; Krishna, K M; Ravi Krishna, C H; Sivanarayana, T; Madan, K; Rama Raju, G A; Annapurna, A

    2015-06-01

    The study was conducted to evaluate the vanadium-induced testicular toxicity and its effect on sperm parameters, sperm nuclear DNA damage and histological alterations in Sprague Dawley rats and to assess the protective effect of G-hesperidin against this damage. Treatment of rats with vanadium at a dose of 1 mg kg bw(-1) for 90 days resulted in significant reduction in serum testosterone levels, sperm count and motility. Further, a parallel increase in abnormal sperm morphology and adverse histopathological changes in testis was also associated with vanadium administration when compared to normal control. Moreover, sperm chromatin dispersion assay revealed that vanadium induces sperm nuclear DNA fragmentation. A marked increase in testicular malondialdehyde levels and decreased activity of antioxidant enzymes such as superoxide dismutase and catalase indicates vanadium-induced oxidative stress. Co-administration of G-hesperidin at a dose of 25 and 50 mg kg bw(-1) significantly attenuated the sperm parameters and histological changes by restoring the antioxidant levels in rat testis. These results suggested that vanadium exposure caused reduced bioavailability of androgens to the tissue and increased free radical formation, thereby causing structural and functional changes in spermatozoa. G-hesperidin exhibited antioxidant effect by protecting the rat testis against vanadium-induced oxidative damage, further ensures antioxidant potential of bioflavonoids. © 2014 Blackwell Verlag GmbH.

  16. Modeling of the Structure of Disordered Metallic Alloys and Its Transformation Under Thermal Forcing

    NASA Astrophysics Data System (ADS)

    Cress, Ryan Paul

    The morphology of disordered binary metallic alloys is investigated. The structure of disordered binary metallic alloys is modeled as a randomly close packed (RCP) assembly of atoms. It was observed through a 2-D binary hard sphere experiment that RCP structure can be modeled as a mixture of nano-crystallites and glassy matter. We define the degree of crystallinity as the fraction of atoms contained in nano-crystallites in an RCP medium. Nano-crystallites by size in a crystallite size distribution were determined experimentally to define the morphology of the RCP medium. Both the degree of crystallinity and the crystallite size distribution have been found to be determined by the composition of a given binary mixture. A 2-D Monte Carlo simulation was developed in order to replicate the RCP structure observed in the experiment which is then extended to cases of arbitrary composition. Crystallites were assumed to be spherical with isotropic cross sections. The number of atoms in an individual crystallite in 2-D is simply transformed into the number of atoms in 3-D; we then obtain the crystallite size distribution in 3-D. This experiment accounts for the contribution from the repulsive core of the inter-atomic potential. The attractive part of the potential is recovered by constructing spherical nano-crystallites of a given radius from a crystalline specimen of each given alloy. A structural model of a disordered alloy is thus obtained. With the basic structure of the RCP medium defined, the response to heating would be in the form of changes to the crystallite size distribution. This was first investigated in a hard sphere mechanical oven experiment. The experimental setup consists of a 2-D cell which is driven by two independent stepper motors. The motors drive a binary RCP bed of spheres on a slightly tilted plane according to a chaotic algorithmm. The motors are driven at four different speed settings. The RCP medium was analyzed using a sequence of digital images

  17. Shifting in optoelectronic properties from pure K2O and Rb2O compounds to their V- and Cr-doped alloys

    NASA Astrophysics Data System (ADS)

    Monir, Mohammed El Amine; Ullah, Hayat; Baltach, Hadj; Mouchaal, Younes; Merabiha, Omar; Bahnes, Aicha; Rached, Djamel

    2018-04-01

    First principle calculations within the density functional theory (DFT) have been used in this approach to study the electronic and optical properties of vanadium (V) and chromium (Cr) doped K2O and Rb2O compounds. Based on the structure properties reported in our previous work, the study of electronic and optoelectronic properties of V- and Cr-doped K2O and Rb2O alloys have been vastly investigated. K2O and Rb2O are found to be semiconductors while their V- and Cr-alloys are metallic in nature. The optical functions like complex dielectric constant, complex index of refraction, absorption coefficient, and reflectivity of these alloys are computed and compared with those of pure K2O and Rb2O compounds. It has been shown that due to TM-doping (TM = V and Cr transition metals), many distinguished peaks appeared in the lower energy part (infrared) of the spectrum. The negative value of 𝜀1 (ω) in this energy range confirmed the metallic behavior of these alloys. Furthermore, the frequency-dependent optical conductivity is also predicted in the entire spectrum, where it increases with increasing photon energy for all the studied alloys. The significant results of α (ω) predict that all these compounds are useful in different optoelectronic applications in a wide part of the spectrum (between 13 eV and 27 eV).

  18. Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement.

    PubMed

    Espinosa, Nieves; Dam, Henrik Friis; Tanenbaum, David M; Andreasen, Jens W; Jørgensen, Mikkel; Krebs, Frederik C

    2011-01-11

    The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V₂O₅·(H₂O) n /Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

  19. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Starke, Edgar A., Jr.; Gangloff, Richard P.; Herakovich, Carl T.; Scully, John R.; Shiflet, Gary J.; Stoner, Glenn E.; Wert, John A.

    1995-01-01

    The NASA-UVa Light Aerospace Alloy and Structures Technology (LA2ST) Program was initiated in 1986 and continues with a high level of activity. Projects are being conducted by graduate students and faculty advisors in the Department of Materials Science and Engineering, as well as in the Department of Civil Engineering and Applied Mechanics, at the University of Virginia. Here, we report on progress achieved between July 1 and December 31, 1994. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. We generally aim to produce relevant data and basic understanding of material mechanical response, environmental/corrosion behavior, and microstructure; new monolithic and composite alloys; advanced processing methods; new solid and fluid mechanics analyses; measurement and modeling advances; and a pool of educated graduate students for aerospace technologies.

  20. Microstructure and mechanical characteristics of gradient structured Cu and Cu alloys processed by surface mechanical attrition treatment

    NASA Astrophysics Data System (ADS)

    Hu, XZ; Cheng, LP; Chen, HL; Yin, Z.; Zhang, Z.; Shu, BP; Gong, YL; Zhu, XK

    2017-05-01

    Cu-Al-Zn alloys with different stacking fault energy (SFE) were processed by surface mechanical attrition treatment (SMAT) at cryogenic temperature (CT), mechanical properties of gradient structured Cu-Al-Zn alloys were investigated in this study. Al and Zn content in alloys, which result in the decrease of SFE, can contribute to the increase in strength. Cu-4.5wt%Al-14.3wt%Zn alloy with the lower SFE shows that the strength increased, the ductility did not decrease significantly with increasing processing time, and the strength can be improved by a thicker gradient structure (GS) layer. The better combination of strength and ductility was achieved in Cu-4.5wt%Al-14.3wt%Zn alloy with lower SFE.

  1. Aging Optimization of Aluminum-Lithium Alloy C458 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H. W.; Farahmand, B.; Rioja, R.

    2003-01-01

    This viewgraph report presents an examination of the fracture toughness of aluminum-lithium alloy C458 for use in cryotank structures. Topics cover include: cryogenics, alloy composition, strengthing precipitates in C458, cryogenic fracture toughness improvements, design of experiments for measuring aging optimization of C458 plate and effects of aging of properties of C458 plate.

  2. Crystal structure and equation of state of Fe-Si alloys at super-Earth core conditions

    DOE PAGES

    Wicks, June K.; Smith, Raymond F.; Fratanduono, Dayne E.; ...

    2018-04-25

    In this paper, the high-pressure behavior of Fe alloys governs the interior structure and dynamics of super-Earths, rocky extrasolar planets that could be as much as ten times more massive than Earth. In experiments reaching up to 1300 GPa, we combine laser-driven dynamic ramp compression with in situ X-ray diffraction to study the effect of composition on the crystal structure and density of Fe-Si alloys, a potential constituent of super-Earth cores. We find that Fe-7wt.%Si adopts the hexagonal close packed (hcp) structure over the measured pressure range, whereas Fe-15wt.%Si is observed in a body-centered cubic (bcc) structure. This study representsmore » the first experimental determination of the density and crystal structure of Fe-Si alloys at pressures corresponding to the center of a ~3 Earth-mass terrestrial planet. Our results allow for direct determination of the effects of light elements on core radius, density, and pressures for such planets.« less

  3. Crystal structure and equation of state of Fe-Si alloys at super-Earth core conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wicks, June K.; Smith, Raymond F.; Fratanduono, Dayne E.

    In this paper, the high-pressure behavior of Fe alloys governs the interior structure and dynamics of super-Earths, rocky extrasolar planets that could be as much as ten times more massive than Earth. In experiments reaching up to 1300 GPa, we combine laser-driven dynamic ramp compression with in situ X-ray diffraction to study the effect of composition on the crystal structure and density of Fe-Si alloys, a potential constituent of super-Earth cores. We find that Fe-7wt.%Si adopts the hexagonal close packed (hcp) structure over the measured pressure range, whereas Fe-15wt.%Si is observed in a body-centered cubic (bcc) structure. This study representsmore » the first experimental determination of the density and crystal structure of Fe-Si alloys at pressures corresponding to the center of a ~3 Earth-mass terrestrial planet. Our results allow for direct determination of the effects of light elements on core radius, density, and pressures for such planets.« less

  4. Surface modification of Ti alloy by electro-explosive alloying and electron-beam treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gromov, Victor, E-mail: gromov@physics.sibsiu.ru; Kobzareva, Tatiana, E-mail: kobzarevatanya@mail.ru; Budovskikh, Evgeniy, E-mail: budovskih-ea@physics.sibsiu.ru

    2016-01-15

    By methods of modern physical metallurgy the analysis of structure phase states of titanium alloy VT6 is carried out after electric explosion alloying with boron carbide and subsequent irradiation by pulsed electron beam. The formation of an electro-explosive alloying zone of a thickness up to 50 µm, having a gradient structure, characterized by decrease in the concentration of carbon and boron with increasing distance to the treatable surface has been revealed. Subsequent electron-beam treatment of alloying zone leads to smoothing of the alloying area surface and is accompanied by the multilayer structure formation at the depth of 30 µm withmore » alternating layers with different alloying degrees having the structure of submicro - and nanoscale level.« less

  5. Amphiphilic block copolymer membrane for vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Sylvia, James M.; Jacob, Monsy M.; Peramunage, Dharmasena

    2013-11-01

    An amphiphilic block copolymer comprised of hydrophobic polyaryletherketone (PAEK) and hydrophilic sulfonated polyaryletherketone (SPAEK) blocks has been synthesized and characterized. A membrane prepared from the block copolymer is used as the separator in a single cell vanadium redox flow battery (VRB). The proton conductivity, mechanical property, VO2+ permeability and single VRB cell performance of this block copolymer membrane are investigated and compared to Nafion™ 117. The block copolymer membrane showed significantly improved vanadium ion selectivity, higher mechanical strength and lower conductivity than Nafion™ 117. The VRB containing the block copolymer membrane exhibits higher coulombic efficiency and similar energy efficiency compared to a VRB using Nafion™ 117. The better vanadium ion selectivity of the block copolymer membrane has led to a much smaller capacity loss during 50 charge-discharge cycles for the VRB.

  6. Characterization of Non-Innocent Metal Complexes Using Solid-State NMR Spectroscopy: o-Dioxolene Vanadium Complexes

    PubMed Central

    Chatterjee, Pabitra B.; Goncharov-Zapata, Olga; Quinn, Laurence L.; Hou, Guangjin; Hamaed, Hiyam; Schurko, Robert W.; Polenova, Tatyana; Crans, Debbie C.

    2012-01-01

    51V solid-state NMR (SSNMR) studies of a series of non-innocent vanadium(V) catechol complexes have been conducted to evaluate the possibility that 51V NMR observables, quadrupolar and chemical shift anisotropies, and electronic structures of such compounds can be used to characterize these compounds. The vanadium(V) catechol complexes described in these studies have relatively small quadrupolar coupling constants, which cover a surprisingly small range from 3.4 to 4.2 MHz. On the other hand, isotropic 51V NMR chemical shifts cover a wide range from −200 ppm to 400 ppm in solution and from −219 to 530 ppm in the solid state. A linear correlation of 51V NMR isotropic solution and solid-state chemical shifts of complexes containing non-innocent ligands is observed. These experimental results provide the information needed for the application of 51V SSNMR spectroscopy in characterizing the electronic properties of a wide variety of vanadium-containing systems, and in particular those containing non-innocent ligands and that have chemical shifts outside the populated range of −300 ppm to −700 ppm. The studies presented in this report demonstrate that the small quadrupolar couplings covering a narrow range of values reflect the symmetric electronic charge distribution, which is also similar across these complexes. These quadrupolar interaction parameters alone are not sufficient to capture the rich electronic structure of these complexes. In contrast, the chemical shift anisotropy tensor elements accessible from 51V SSNMR experiments are a highly sensitive probe of subtle differences in electronic distribution and orbital occupancy in these compounds. Quantum chemical (DFT) calculations of NMR parameters for [VO(hshed)(Cat)] yield 51V CSA tensor in reasonable agreement with the experimental results, but surprisingly, the calculated quadrupolar coupling constant is significantly greater than the experimental value. The studies demonstrate that substitution of the

  7. Overview of environmental and occupational vanadium exposure and associated health outcomes: an article based on a presentation at the 8th International Symposium on Vanadium Chemistry, Biological Chemistry, and Toxicology, Washington DC, August 15-18, 2012.

    PubMed

    Fortoul, T I; Rojas-Lemus, M; Rodriguez-Lara, V; Gonzalez-Villalva, A; Ustarroz-Cano, M; Cano-Gutierrez, G; Gonzalez-Rendon, S E; Montaño, L F; Altamirano-Lozano, M

    2014-01-01

    Vanadium (V) has a variety of applications that make it suitable for use in ceramic production and decoration, production of pigments for a variety of products, an accelerator for drying paint, production of aniline black dye, and as a mordant in coloring textiles. Taking advantage of its hardness, resilience, ability to form alloys, and its resistance to corrosion, V is also used in the production of tools, steel, machinery, and surgical implants. V is employed in producing photographic developers, batteries, and semi-conductors, and in catalyst-based recycling processes. As technologies have evolved, the use of V has increased in jet aircraft and space technology, as well as in manufacture of ultraviolet filter glass to prevent radiation injury. Due to these myriad uses, the potential for occupational exposure to V is ever-evident. Similarly, there is an increased risk for environmental contamination by V agents themselves or as components of by-products released into the environment. For example, the use of V in sulfuric acid production results in the release of soot and/or fly ash rich in vanadium pentoxide. Petroleum refinery, smelting, welding, and cutting of V-rich steel alloy, the cleaning and repair of oil-fired boilers, and catalysis of chemical productions are other sources of increased airborne V-bearing particles in local/distant environments. Exposure of non-workers to V is an increasing health concern. Studies have demonstrated associations between exposure to airborne V-bearing particles (as part of air pollution) and increased risks of a variety of pathologies like hypertension, dysrhythmia, systemic inflammation, hyper-coagulation, cancers, and bronchial hyper-reactivity. This paper will provide a review of the history of V usage in occupational settings, documented exposure levels, environmental levels of V associated with pollution, epidemiologic data relating V exposure(s) to adverse health outcomes, and governmental responses to protect both

  8. Reactions of sulfur dioxide with neutral vanadium oxide clusters in the gas phase. I. Density functional theory study.

    PubMed

    Jakubikova, Elena; Bernstein, Elliot R

    2007-12-27

    Thermodynamics of reactions of vanadium oxide clusters with SO2 are studied at the BPW91/LANL2DZ level of theory. BPW91/LANL2DZ is insufficient to properly describe relative V-O and S-O bond strengths of vanadium and sulfur oxides. Calibration of theoretical results with experimental data is necessary to compute reliable enthalpy changes for reactions between VxOy and SO2. Theoretical results indicate SO2 to SO conversion occurs for oxygen-deficient clusters and SO2 to SO3 conversion occurs for oxygen-rich clusters. Stable intermediate structures of VOy (y = 1 - 4) clusters with SO2 are also obtained at the BPW91/TZVP level of theory. Some possible mechanisms for SO3 formation and catalyst regeneration for condensed-phase systems are suggested. These results are in agreement with, and complement, gas-phase experimental studies of neutral vanadium oxide clusters.

  9. The Influence of Vanadium on Ferrite and Bainite Formation in a Medium Carbon Steel

    NASA Astrophysics Data System (ADS)

    Sourmail, T.; Garcia-Mateo, C.; Caballero, F. G.; Cazottes, S.; Epicier, T.; Danoix, F.; Milbourn, D.

    2017-09-01

    The influence of vanadium additions on transformation kinetics has been investigated in a medium carbon forging steel. Using dilatometry to track transformation during continuous cooling or isothermal transformation, the impact of vanadium on both ferrite-pearlite and bainite has been quantified. Transmission electron microscopy and atom probe tomography have been used to establish whether vanadium was present in solid solution, or as clusters and precipitates. The results show that vanadium in solid solution has a pronounced retarding influence on ferrite-pearlite formation and that, unlike in the case of niobium, this effect can be exploited even during relatively slow cooling. The influence on bainite transformation was found to depend on temperature; an explanation in terms of the effect of vanadium on heterogeneous nucleation is tentatively proposed.

  10. Lithium vanadium oxides (Li1+xV3O8) as cathode materials in lithium-ion batteries for soldier portable power systems

    NASA Astrophysics Data System (ADS)

    Wang, Gaojun; Chen, Linfeng; Mathur, Gyanesh N.; Varadan, Vijay K.

    2011-04-01

    Improving soldier portable power systems is very important for saving soldiers' lives and having a strategic advantage in a war. This paper reports our work on synthesizing lithium vanadium oxides (Li1+xV3O8) and developing their applications as the cathode (positive) materials in lithium-ion batteries for soldier portable power systems. Two synthesizing methods, solid-state reaction method and sol-gel method, are used in synthesizing lithium vanadium oxides, and the chemical reaction conditions are determined mainly based on thermogravimetric and differential thermogravimetric (TG-DTG) analysis. The synthesized lithium vanadium oxides are used as the active positive materials in the cathodes of prototype lithium-ion batteries. By using the new solid-state reaction technique proposed in this paper, lithium vanadium oxides can be synthesized at a lower temperature and in a shorter time, and the synthesized lithium vanadium oxide powders exhibit good crystal structures and good electrochemical properties. In the sol-gel method, different lithium source materials are used, and it is found that lithium nitrate (LiNO3) is better than lithium carbonate (Li2CO3) and lithium hydroxide (LiOH). The lithium vanadium oxides synthesized in this work have high specific charge and discharge capacities, which are helpful for reducing the sizes and weights, or increasing the power capacities, of soldier portable power systems.

  11. Visible Thermochromism in Vanadium Pentoxide Coatings.

    PubMed

    Kumar, Sunil; Qadir, Awais; Maury, Francis; Bahlawane, Naoufal

    2017-06-28

    Although di-vanadium pentoxide (V 2 O 5 ) has been a candidate of extensive research for over half a century, its intrinsic thermochromism has not been reported so far. Films of V 2 O 5 grown on silicon, glass, and metal substrates by metal organic chemical vapor deposition in this study exhibit a thermally induced perceptible color change from bright yellow to deep orange. Temperature-dependent UV-vis spectroscopy and X-ray diffraction allow the correlation between the reversible continuous red shift of the absorption and the anisotropic thermal expansion along the (001) direction, that is, perpendicular to the sheets constituting the layered structure. Furthermore, the possibility of tuning the thermochromic behavior was demonstrated via a chemical doping with chromium.

  12. Structural and magnetic properties of FeCoC system obtained by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Rincón Soler, A. I.; Rodríguez Jacobo, R. R.; Medina Barreto, M. H.; Cruz-Muñoz, B.

    2017-11-01

    Fe96-XCoXC4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

  13. A comparative assessment of the acute inhalation toxicity of vanadium compounds.

    PubMed

    Rajendran, N; Seagrave, J C; Plunkett, L M; MacGregor, J A

    2016-11-01

    Vanadium compounds have become important in industrial processes, resulting in workplace exposure potential and are present in ambient air as a result of fossil fuel combustion. A series of acute nose-only inhalation toxicity studies was conducted in both rats and mice in order to obtain comparative data on the acute toxicity potential of compounds used commercially. V 2 O 3 , V 2 O 4 , and V 2 O 5 , which have different oxidation states (+3, +4, +5, respectively), were delivered as micronized powders; the highly water-soluble and hygroscopic VOSO 4 (+4) could not be micronized and was instead delivered as a liquid aerosol from an aqueous solution. V 2 O 5 was the most acutely toxic micronized powder in both species. Despite its lower overall percentage vanadium content, a liquid aerosol of VOSO 4 was more toxic than the V 2 O 5 particles in mice, but not in rats. These data suggest that an interaction of characteristics, i.e., bioavailability, solubility and oxidation state, as well as species sensitivity, likely affect the toxicity potential of vanadium compounds. Based on clinical observations and gross necropsy findings, the lung appeared to be the target organ for all compounds. The level of hazard posed will depend on the specific chemical form of the vanadium. Future work to define the inhalation toxicity potential of vanadium compounds of various oxidation states after repeated exposures will be important in understanding how the physico-chemical and biological characteristics of specific vanadium compounds interact to affect toxicity potential and the potential risks posed to human health.

  14. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    NASA Astrophysics Data System (ADS)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  15. NASA-UVA light aerospace alloy and structures technology program (LA2ST)

    NASA Technical Reports Server (NTRS)

    Gangloff, Richard P.; Starke, Edger A., Jr.

    1996-01-01

    This progress report covers achievements made between January 1 and June 30, 1966 on the NASA-UVA Light Aerospace Alloy and Structures Technology (LA2ST) Program. The objective of the LA2ST Program is to conduct interdisciplinary graduate student research on the performance of next generation, light-weight aerospace alloys, composites and thermal gradient structures in collaboration with NASA-Langley researchers. Specific technical objectives are presented for each research project. . The accomplishments presented in this report are: (1) Mechanical and Environmental Degradation Mechanisms in Advanced Light Metals, (2) Aerospace Materials Science, and (3) Mechanics of Materials for Light Aerospace Structures. Collective accomplishments between January and June of 1996 include: 4 journal or proceedings publications, 1 NASA progress report, 4 presentations at national technical meetings, and 2 PhD dissertations published.

  16. 40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

  17. 40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

  18. 40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

  19. High strength ferritic alloy-D53

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high strength ferritic alloy is described having from about 0.2% to about 0.8% by weight nickel, from about 2.5% to about 3.6% by weight chromium, from about 2.5% to about 3.5% by weight molybdenum, from about 0.1% to about 0.5% by weight vanadium, from about 0.1% to about 0.5% by weight silicon, from about 0.1% to about 0.6% by weight manganese, from about 0.12% to about 0.20% by weight carbon, from about 0.02% to about 0.1% by weight boron, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight phosphorous, a maximum of about 0.02% by weight sulfur, and the balance iron.

  20. Spectrophotometric determination of vanadium and its application to gas-turbine fuel-oils.

    PubMed

    Banerjee, S; Sinha, B P; Dutta, R K

    1975-08-01

    A very sensitive spectrophotometric method for the determination of vanadium in furnace oils is described. The intense indigo-blue colour developed by the reaction of vanadium with tannin and thioglycollic acid is measured at a wavelength of 600 nm at pH 4 and obeys Beer's law between 0.5 and 5 ppm vanadium. The method is applicable to gas-turbine fuel-oil and special navy fuel-oils. The common mineral constituents usually present in such oils do not interfere.

  1. [Interaction Between Occupational Vanadium Exposure and hsp70-hom on Neurobehavioral Function].

    PubMed

    Zhang, Qin; Liu, Yun-xing; Cui, Li; Li, Shun-pin; Gao, Wei; Hu, Gao-lin; Zhang, Zu-hui; Lan, Ya-jia

    2016-01-01

    In determine the effect of heat shock protein 70-hom gene (hsp70-hom) polymorphism on the neurobehavioral function of workers exposed to vanadium. Workers from the vanadium products and chemical industry were recruited by cluster sampling. Demographic data and exposure information were collected using a questionnaire. Neurobehavioral function was assessed by Neurobehavioral Core Test Battery. The hsp70-hom genotype was detected by restricted fragment length polymorphism-polymerase chain reaction (RFLP-PCR). A neurobehavioral index (NBI) was formulated through principal component analysis. Workers with a T/C genotype had worse performance in average reaction time, visual retention, digital span (backward), Santa Ana aiming (non-habitual hand), pursuit aiming (right points, total points), digit symbol and NBI score than others (P < 0.05). The relative risk of abnormal NBI score of the workers with a T/C genotype was 1.748 fold of those with a T/T genotype. The relative risk of abnormal.NBI score of the workers exposed to vanadium was 3.048 fold of controls (P < 0.05). But after adjustment with age and education, only vanadium exposure appeared with a significant effect on NBI score. When gene polymorphism and vanadium exposure coexisted, the effect of vanadium on neurobehavioral function was attenuated, but the influence of T/C genotype increased Codds ratio (OR = 4.577, P < 0.05). After adjustment with age and education, the OR of T/C genotype further increased to 7.777 (P < 0.05). Vanadium exposure and T/C genotype had.a bio-interaction effect on NBI score Crelative excess risk due to interaction (RERI) = 4.12, attributable proportion (AP) = 0.7, synergy index (S) = 6.45]. After adjustment with age and education, the RERI became 2.49 and the AP became 0.75, but no coefficient of interaction was produced. Priorities of occupational protection should be given to vanadium-exposed workers with a hsp70-hom T/C genotype and low education level.

  2. Temperature-dependent gel-type ionic liquid compounds based on vanadium-substituted polyoxometalates with Keggin structure.

    PubMed

    Huang, Tianpei; Xie, Zhirong; Wu, Qingyin; Yan, Wenfu

    2016-03-07

    A series of temperature-dependent gel-type ionic liquid compounds have been synthesized from 1-(3-sulfonic group) propyl-3-methyl imidazolium (abbreviated as MIMPS) and three vanadium-substituted heteropoly acids H5SiW11VO40, H5SiMo11VO40 and H7SiW9V3O40. The designed and synthesized gel-type polyoxometalate ionic liquids (POM-ILs) have demonstrated a tendency to exhibit a layered structure. Moreover, they can undergo a phase transformation from a viscous gel-state to a liquid-state below 100 °C, and ionic conductivity up to 10(-3) S cm(-1) was observed at 120 °C. Cyclic voltammetry was carried out to study their electrochemical properties in organic solutions, and it was found that the oxidizability of the three POM-ILs decreases in the order: [MIMPS]7SiW9V3O40 > [MIMPS]5SiMo11VO40 > [MIMPS]5SiW11VO40. This result indicates that the redox behavior can be tuned by changing the chemical composition of the heteropolyanions.

  3. The presence of vanadium in groundwater of southeastern extreme the pampean region Argentina Relationship with other chemical elements.

    PubMed

    Fiorentino, Carmen E; Paoloni, Juan D; Sequeira, Mario E; Arosteguy, Pedro

    2007-08-15

    Changes in the quality of groundwater resources are related to the presence and concentration of contaminants, especially trace elements such as arsenic, boron, fluoride and vanadium. Vanadium is a rare element naturally abundant, generally found in combination with other elements. Vanadium pentoxide is known to have aneugenic effects. Thus, a study was carried out to assess the presence of vanadium in the groundwater of the southeastern pampean region of Argentina, which constitutes the main water supply for the local population. Statistical and correlational analyses were applied to identify possible interrelationships between vanadium and another chemical elements. Vanadium was found in all groundwater samples. The minimum and maximum vanadium concentrations found were 0.05 mg/l and 2.47 mg/l, respectively. Vanadium is significantly correlated with other trace elements such as arsenic, fluoride and boron. The interrelationship between vanadium and the presence of volcanic glass in sediments is not significant as expected.

  4. Phase transition and strength of vanadium under shock compression up to 88 GPa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yu, Yuying, E-mail: yuyinyu@caep.cn; Tan, Ye; Dai, Chengda

    A series of reverse-impact experiments were performed on vanadium at shock pressure ranging from 32 GPa to 88 GPa. Particle velocity profiles measured at sample/LiF window interface were used to estimate the sound velocities, shear modulus, and yield stress in shocked vanadium. A phase transition at ∼60.5 GPa that may be the body-centered cubic (BCC) to rhombohedral structure was identified by the discontinuity of the sound velocity against shock pressure. This transition pressure is consistent with the results from diamond anvil cell (DAC) experiments and first-principle calculations. However, present results show that the rhombohedral phase has higher strength and shear modulus than themore » BCC phase, which is contrast to the findings from DAC experiments and theoretical work.« less

  5. Plasma assisted facile synthesis of vanadium oxide (V3O7) nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Singh, Megha; Saini, Sujit K.; Kumar, Prabhat; Sharma, Rabindar K.; Reddy, G. B.

    2018-05-01

    Vanadium oxides nanostructured thin films are synthesized using plasma assisted sublimation process. The effect of temperatures on growth of V2O5 and V3O7 thin films is studied. Scanning electron micrographs shows different morphologies are obtained at different temperatures i.e. at 450 °C nano cubes-like structures are obtained, whereas at 550 °C and 650 °C nanorods are obtained. Sample deposited at 450 °C is entirely composed of V2O5 and sample at higher temperatures are composed of mixed phase of vanadium oxides i.e. V2O5 and V3O7. As temperature increased, so the content of V3O7 in the sample is increased as confirmed by XRD and Raman analyses.

  6. Investigation on the fates of vanadium and nickel during co-gasification of petroleum coke with biomass.

    PubMed

    Li, Jiazhou; Wang, Xiaoyu; Wang, Bing; Zhao, Jiantao; Fang, Yitian

    2018-06-01

    This study investigates the volatilization behaviors and mineral transformation of vanadium and nickel during co-gasification of petroleum coke with biomass. Moreover, the evolution of occurrence modes of vanadium and nickel was also determined by the method of sequential chemical extraction. The results show that the volatilities of vanadium and nickel in petroleum coke have a certain level of growth with an increase in the temperature. With the addition of biomass, their volatilities both show an obvious decrease. Organic matter and stable forms are the dominant chemical forms of vanadium and nickel. After gasification, organic-bound vanadium and nickel decompose completely and convert into other chemical forms. The crystalline phases of vanadium trioxide, coulsonite, nickel sulfide, and elemental nickel are clearly present in petroleum coke and biomass gasification ashes. When the addition of biomass reaches 60 wt%, the diffraction peaks of orthovanadate are found while that of vanadium trioxide disappear. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Hydrophilic Channel Alignment of Perfluoronated Sulfonic-Acid Ionomers for Vanadium Redox Flow Batteries.

    PubMed

    So, Soonyong; Cha, Min Suc; Jo, Sang-Woo; Kim, Tae-Ho; Lee, Jang Yong; Hong, Young Taik

    2018-06-13

    It is known that uniaxially drawn perfluoronated sulfonic-acid ionomers (PFSAs) show diffusion anisotropy because of the aligned water channels along the deformation direction. We apply the uniaxially stretched membranes to vanadium redox flow batteries (VRFBs) to suppress the permeation of active species, vanadium ions through the transverse directions. The aligned water channels render much lower vanadium permeability, resulting in higher Coulombic efficiency (>98%) and longer self-discharge time (>250 h). Similar to vanadium ions, proton conduction through the membranes also decreases as the stretching ratio increases, but the thinned membranes show the enhanced voltage and energy efficiencies over the range of current density, 50-100 mA/cm 2 . Hydrophilic channel alignment of PFSAs is also beneficial for long-term cycling of VRFBs in terms of capacity retention and cell performances. This simple pretreatment of membranes offers an effective and facile way to overcome high vanadium permeability of PFSAs for VRFBs.

  8. Protective effects of Sesamum indicum extract against oxidative stress induced by vanadium on isolated rat hepatocytes.

    PubMed

    Hosseini, Mir-Jamal; Shahraki, Jafar; Tafreshian, Saman; Salimi, Ahmad; Kamalinejad, Mohammad; Pourahmad, Jalal

    2016-08-01

    Vanadium toxicity is a challenging problem to human and animal health with no entirely understanding cytotoxic mechanisms. Previous studies in vanadium toxicity showed involvement of oxidative stress in isolated liver hepatocytes and mitochondria via increasing of ROS formation, release of cytochrome c and ATP depletion after incubation with different concentrations (25-200 µM). Therefore, we aimed to investigate the protective effects of Sesamum indicum seed extract (100-300 μg/mL) against oxidative stress induced by vanadium on isolated rat hepatocytes. Our results showed that quite similar to Alpha-tocopherol (100 µM), different concentrations of extract (100-300 μg/mL) protected the isolated hepatocyte against all oxidative stress/cytotoxicity markers induced by vanadium in including cell lysis, ROS generation, mitochondrial membrane potential decrease and lysosomal membrane damage. Besides, vanadium induced mitochondrial/lysosomal toxic interaction and vanadium reductive activation mediated by glutathione in vanadium toxicity was significantly (P < 0.05) ameliorated by Sesamum indicum extracts. These findings suggested a hepato-protective role for extracts against liver injury resulted from vanadium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 979-985, 2016. © 2015 Wiley Periodicals, Inc.

  9. Thermodynamics of Alloys: Studies of Nickel-Gallium, Nickel-Germanium and Nickel-Rhodium Alloys.

    DTIC Science & Technology

    NICKEL ALLOYS, *GALLIUM ALLOYS, *GERMANIUM ALLOYS, * RHODIUM ALLOYS, *PHASE STUDIES, THERMODYNAMICS, INTERMETALLIC COMPOUNDS, FREE ENERGY, ENTROPY, HEAT OF FORMATION, CRYSTAL STRUCTURE, UNITED KINGDOM.

  10. Predicting the Crystal Structure and Phase Transitions in High-Entropy Alloys

    NASA Astrophysics Data System (ADS)

    King, D. M.; Middleburgh, S. C.; Edwards, L.; Lumpkin, G. R.; Cortie, M.

    2015-06-01

    High-entropy alloys (HEAs) have advantageous properties compared with other systems as a result of their chemistry and crystal structure. The transition between a face-centered cubic (FCC) and body-centered cubic (BCC) structure in the Al x CoCrFeNi high-entropy alloy system has been investigated on the atomic scale in this work. The Al x CoCrFeNi system, as well as being a useful system itself, can also be considered a model HEA material. Ordering in the FCC structure was investigated, and an order-disorder transition was predicted at ~600 K. It was found that, at low temperatures, an ordered lattice is favored over a truly random lattice. The fully disordered BCC structure was found to be unstable. When partial ordering was imposed (lowering the symmetry), with Al and Ni limited specific sites of the BCC system, the BCC packing was stabilized. Decomposition of the ordered BCC single phase into a dual phase (Al-Ni rich and Fe-Cr rich) is also considered.

  11. 76 FR 78888 - Final Results of Expedited Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-20

    ... Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia AGENCY: Import Administration... and nitrided vanadium from the Russian Federation (Russia), pursuant to section 751(c) of the Tariff... vanadium from Russia, pursuant to section 751(c) of the Act. See Initiation of Five-Year (``Sunset...

  12. Current status and associated human health risk of vanadium in soil in China.

    PubMed

    Yang, Jie; Teng, Yanguo; Wu, Jin; Chen, Haiyang; Wang, Guoqiang; Song, Liuting; Yue, Weifeng; Zuo, Rui; Zhai, Yuanzheng

    2017-03-01

    A detailed assessment of vanadium contamination characteristics in China was conducted based on the first national soil pollution survey. The map overlay analysis was used to evaluate the contamination level of vanadium and the non-carcinogenic risk assessment model was calculated to quantify the vanadium exposure risks to human health. The results showed that, due to the drastically increased mining and smelting activities, 26.49% of soils were contaminated by vanadium scattered in southwest of China. According to Canadian soil quality guidelines, about 8.6% of the national soil pollution survey samples were polluted, and pose high non-carcinogenic risks to the public, especially to children living in the vicinity of heavily polluted mining areas. We propose the area near the boundary of Yunnan, Guizhou, Guangxi, and Sichuan provinces as priority control areas due to their higher geochemical background or higher health risks posed to the public. Finally, recommendations for management are proposed, including minimization of contaminant inputs, establishing stringent monitoring program, using phytoremediation, and strengthening the enforcement of relevant laws. Therefore, this study provides a comprehensive assessment of soil vanadium contamination in China, and the results will provide valuable information for China's soil vanadium management and risk avoidance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. In vitro bioactivity investigations of Ti-15Mo alloy after electrochemical surface modification.

    PubMed

    Kazek-Kęsik, Alicja; Kuna, Karolina; Dec, Weronika; Widziołek, Magdalena; Tylko, Grzegorz; Osyczka, Anna M; Simka, Wojciech

    2016-07-01

    Titanium and its aluminum and vanadium-free alloys have especially great potential for medical applications. Electrochemical surface modification improves their surface bioactivity and stimulates osseointegration process. In this work, the effect of plasma electrolytic oxidation of the β-type alloy Ti-15Mo surface on its bioactivity is presented. Bioactivity of the modified alloy was investigated by immersion in simulated body fluid (SBF). Biocompatibility of the modified alloys were tested using human bone marrow stromal cells (hBMSC) and wild intestinal strains (DV/A, DV/B, DV/I/1) of Desulfovibrio desulfuricans bacteria. The particles of apatite were formed on the anodized samples. Human BMSC cells adhered well on all the examined surfaces and expressed ALP, collagen, and produced mineralized matrix as determined after 10 and 21 days of culture. When the samples were inoculated with D. desulfuricans bacteria, only single bacteria were visible on selected samples. There were no obvious changes in surface morphology among samples. Colonization and bacterial biofilm formation was observed on as-ground sample. In conclusion, the surface modification improved the Ti-15Mo alloy bioactivity and biocompatibility and protected surface against colonization of the bacteria. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 903-913, 2016. © 2015 Wiley Periodicals, Inc.

  14. The determination of vanadium in brines by atomic absorption spectroscopy

    USGS Publications Warehouse

    Crump-Wiesner, Hans J.; Feltz, H.R.; Purdy, W.C.

    1971-01-01

    A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

  15. The structure-property relationships of powder processed Fe-Al-Si alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prichard, Paul D.

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) processmore » to obtain a high fraction of metal injection molding (MIM) quality powder (D 84 < 32 μm). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 μm. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 μm to 104 μm. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase α + DO 3 structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.« less

  16. 77 FR 54897 - Ferrovanadium and Nitrided Vanadium from the Russian Federation: Revocation of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-06

    ... nitrided vanadium from the Russian Federation (Russia) would not be likely to lead to continuation or... the antidumping duty order on ferrovanadium and nitrided vanadium from Russia. \\1\\ See Ferrovanadium and Nitrided Vanadium From Russia, 77 FR 51825 (August 27, 2012) (ITC Final). DATES: Effective Date...

  17. Growth control of the oxidation state in vanadium oxide thin films

    DOE PAGES

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

    2014-12-05

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

  18. Growth control of the oxidation state in vanadium oxide thin films

    NASA Astrophysics Data System (ADS)

    Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

    2014-12-01

    Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

  19. Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement

    PubMed Central

    Espinosa, Nieves; Dam, Henrik Friis; Tanenbaum, David M.; Andreasen, Jens W.; Jørgensen, Mikkel; Krebs, Frederik C.

    2011-01-01

    The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2O)n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker. PMID:28879984

  20. Structure and Mechanical and Corrosion Properties of a Magnesium Mg-Y-Nd-Zr Alloy after High Pressure Torsion

    NASA Astrophysics Data System (ADS)

    Lukyanova, E. A.; Martynenko, N. S.; Serebryany, V. N.; Belyakov, A. N.; Rokhlin, L. L.; Dobatkin, S. V.; Estrin, Yu. Z.

    2017-11-01

    The structure and the properties of an Mg-Y-Nd-Zr alloy (WE43) are studied after high pressure torsion (HPT) in the temperature range 20-300°C. Structure refinement proceeds mainly by deformation twinning with the formation of a partial nanocrystalline structure with a grain size of 30-100 nm inside deformation twins. The WE43 alloy is shown to be aged during heating after HPT due to the decomposition of a magnesium solid solution. HPT at room temperature and subsequent aging causes maximum hardening. It is shown that HPT significantly accelerates the decomposition of a magnesium solid solution. HPT at all temperatures considerably increases the tensile strength and the yield strength upon tensile tests and significantly decreases plasticity. Subsequent aging additionally hardens the WE43 alloy. A potentiodynamic study shows that the corrosion resistance of this alloy after HPT increases. However, subsequent aging degrades the corrosion properties of the alloy.