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Sample records for activation vanadium alloy

  1. Manufacturing development of low activation vanadium alloys

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of the new upper divertor structure. The first step, procuring the material for this program has been completed. The largest heat of vanadium alloy made to date, 1200 kg of V-4Cr-4Ti, has been produced and is being converted into various product forms. Results of many tests on the material during the manufacturing process are reported. Research into potential fabrication methods has been and continues to be performed along with the assessment of manufacturing processes particularly in the area of joining. Joining of vanadium alloys has been identified as the most critical fabrication issue for their use in the Radiative Divertor Program. Joining processes under evaluation include resistance seam, electrodischarge (stud), friction and electron beam welding. Results of welding tests are reported. Metallography and mechanical tests are used to evaluate the weld samples. The need for a protective atmosphere during different welding processes is also being determined. General Atomics has also designed, manufactured, and will be testing a helium-cooled, high heat flux component to assess the use of helium cooled vanadium alloy components for advanced tokamak systems. The component is made from vanadium alloy tubing, machined to enhance the heat transfer characteristics, and joined to end flanges to allow connection to the helium supply. Results are reported

  2. Vanadium alloys: development strategy

    A strategy for the development of vanadium alloys for use in radiation environments is outlined. An attractive reference alloy (V-15Cr-5Ti) has been identified. The critical issues in developing vanadium base alloys are summarized

  3. Development of low activation vanadium alloys. Final report for period 1992-1994

    In the period 92-94 ECN carried out a task tilted 'Development of low activation alloys' in the frame of the European Fusion Technology Programme. The work included helium implantation, neutron irradiation and post-irradiation mechanical testing of eight vanadium alloys and three purities of vanadium. Helium and oxygen affect the mechanical properties. Helium injection followed by neutron irradiation has the most embrittling effect. Quantitative modelling of the alloy behaviour needs improvement to explain the observed phenomena. (orig.)

  4. Activation experiments on vanadium alloy NIFS-HEAT-2

    In the present study, activation analysis of impurities and evaluation of activation properties were performed on NIFS-HEAT-2 by DT neutron irradiation at FNS facility. Similar analysis and evaluation were performed on US and Chinese V-4Cr-Ti samples for comparison. For impurity analysis and direct evaluation of activation properties of vanadium alloys, activation experiments with DT neutron irradiations were performed on NIFS-HEAT-2 and Round-Robin samples from the US and China. Eight nuclides of 24Na, 28Al, 54Mn, 56Mn, 57Co, 58Co, 89Zr and 92mNb were identified form analysis of the gamma peaks and concentrations of Al, Si, Mn, Fe, Ni, Co, Zr, Nb and Mo were evaluated. It was confirmed that the concentration of Al in NIFS-HEAT-2, which is harmful for low activation property, was lower than the criteria required for recycling of used material after reactor shutdown. The results were almost consistent with those by chemical analysis. Until ∼8 months after irradiation, significant influence of impurities was not observed in the decay heat measurement. Results of decay heat measurement with the Whole Energy Absorption Spectrometer and those of calculation with MNCP-4C, ACT-4 and JENDL Activation File were consistent within ∼ 15%. Activation calculation considering impurity concentrations from the present analysis indicated that decay heat of 60Co transmuted from Ni impurity will be dominant ∼6 years after irradiation. (author)

  5. ATR-A1 irradiation experiment on vanadium alloys and low activation steels

    Tasi, H.; Strain, R.V.; Gomes, I.; Hins, A.G.; Smith, D.L.

    1996-04-01

    To study the mechanical properties of vanadium alloys under neutron irradiation at low temperatures, an experiment was designed and constructed for irradiation in the Advanced Test Reactor (ATR). The experiment contained Charpy, tensile, compact tension, TEM, and creep specimens of vanadium alloys. It also contained limited low-activation ferritic steel specimens as part of the collaborative agreement with Monbusho of Japan. The design irradiation temperatures for the vanadium alloy specimens in the experiment are {approx}200 and 300{degrees}C, achieved with passive gap-gap sizing and fill gas blending. To mitigate vanadium-to-chromium transmutation from the thermal neutron flux, the test specimens are contained inside gadolinium flux filters. All specimens are lithium-bonded. The irradiation started in Cycle 108A (December 3, 1995) and is expected to have a duration of three ATR cycles and a peak influence of 4.4 dpa.

  6. Low Activation Vanadium Alloys for Fusion Power Reactors - the RF Results

    Full text: The Results of development and researches of functional properties of low activation vanadium alloys (V-Ti-Cr and V-Cr-W-Zr-C systems) being developed for the cores of nuclear fusion and fission (Gen-IV, space) power reactors are presented. Scientific and technological problems of the investigations are related with enhancement of functional properties based on: 1. Special optimized thermal (TT), thermomechanical (TMT) and thermochemical (TCT) treatments of V-4Ti-4Cr alloys. 2. Development of new (V-Cr-W-Zr-C system) vanadium alloys. The TMT and TCT regimes ensuring the capability of significant (up to 2 times) enhancement of yield strength in the temperature range up to 800°C keeping relatively high plasticity reserve have been found for alloys. The results of the theoretical, modeling and simulating studies of characteristics of self-point defects and dislocations, their interactions and mobility are presented. Nuclear physics characteristics (primary radiation damage, activation, transmutation, postreactor cooling) of alloys irradiated for a long time in neutron spectra of the fusion reactor DEMO-RF (15.3 dpa/year) and fast power reactor BN-600 (80 dpa/year) are calculated. The interaction characteristics of V-4Ti-4Cr alloy with hydrogen and the influence of hydrogen on mechanical properties of the alloy (impact toughness, internal friction) have been studied. Obtained results allows one to recommend the vanadium alloys for applications in nuclear reactors at operating temperature window 300 - 800(850)°C. The planes of high-dose and high- temperature reactor tests of vanadium alloys are scheduled at material science assemblies of reactor BN-600 (2013 - 2015, doses 50 - 200 dpa, irradiation temperatures 400 - 800°C). (author)

  7. Development of manufacturing technology for high purity low activation vanadium alloys

    Vanadium alloys are promising candidate low activation materials for structural components of fusion reactors. Establishment of industrial infrastructure is, however, remaining to be a critical issue because of lack of other large scale commercial applications. In the present study, technologies for large scale manufacturing of high purity V-4Cr-4Ti alloy were developed by improving the present commercial production processes of vanadium metal, and optimizing alloying, plating, sheeting and wiring techniques. Efforts were focused on reducing carbon, nitrogen and oxygen impurities, which are known to deteriorate workability, weldability and radiation resistance of vanadium alloys. Especially, improvements were made in atmospheric control during calcination, aluminothermic reduction, vacuum arc remelting, and hot forging and rolling. A medium size (30kg) high purity V-4Cr-4Ti ingot was produced and designated as NIFS-HEAT-1. The specimens produced out of the ingot are being submitted to Round-robin tests by Japanese universities. Two larger ingots of 166kg in total weight were produced recently (NIFS-HEAT-2(A) and (B)). By these efforts, technology for fabricating large V-4Cr-4Ti alloy products with <100ppm C, ∼100ppm N and 100∼200ppm O was demonstrated. (author)

  8. A zero-waste option: recycling and clearance of activated vanadium alloys

    The reduction of long-term radioactivity is analysed here in V-Cr-Ti alloys, one of the proposed structural materials for fusion power plants. In particular is explored the possibility of recycling within the nuclear industry and of clearance, that is declassification to non-active material. Vanadium alloys have the potential to reach the dose rate hands-on recycling limit when used in a blanket, if noxious radioactive products coming from impurities activation are eliminated. Clearance is also possible in principle, but only if further separation of activation products of titanium is carried out after service

  9. A zero-waste option: Recycling and clearance of activated vanadium alloys

    The reduction of long-term radioactivity is analysed here in V-Cr-Ti alloys, one of the proposed structural materials for fusion power reactors. In particular, it is explored the possibility of recycling within the nuclear industry or clearance, that is declassification to non-active material. Vanadium alloys have the potential to reach the dose rate hands-on recycling limit when used in a blanket, if noxious radioactive products coming from impurities activation are eliminated. Clearance is possible in principle too, however only if a further separation of activation products of titanium is done after service. (author)

  10. Status of ATR-A1 irradiation experiment on vanadium alloys and low-activation steels

    Tsai, H.; Strain, R.V.; Gomes, I.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1996-10-01

    The ATR-A1 irradiation experiment was a collaborative U.S./Japan effort to study at low temperature the effects of neutron damage on vanadium alloys. The experiment also contained a limited quantity of low-activation ferritic steel specimens from Japan as part of the collaboration agreement. The irradiation started in the Advanced Test Reactor (ATR) on November 30, 1995, and ended as planned on May 5, 1996. Total exposure was 132.9 effective full power days (EFPDs) and estimated neutron damage in the vanadium was 4.7 dpa. The vehicle has been discharged from the ATR core and is scheduled to be disassembled in the next reporting period.

  11. Activation and clearance of vanadium alloys and beryllium multipliers in fusion reactors

    Bartenev, S.A. [V.G. Khlopin Radium Institute, 2nd Murinskij Prospect 28, 194021 St. Petersburg (Russian Federation); Ciampichetti, A. [EURATOM/ENEA Fusion Association, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Firsin, N.G. [V.G. Khlopin Radium Institute, 2nd Murinskij Prospect 28, 194021 St. Petersburg (Russian Federation); Forrest, R. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Kolbasov, B.N. [Nuclear Fusion Institute, Russian Research Centre ' Kurchatov Institute' , pl. Kurchatova 1, 123182 Moscow (Russian Federation); Romanov, P.V. [Federal Agency for Atomic Energy, Bolshaya Ordynka 24-26, 109017 Moscow (Russian Federation); Romanovskij, V.N. [V.G. Khlopin Radium Institute, 2nd Murinskij Prospect 28, 194021 St. Petersburg (Russian Federation); Zucchetti, M. [EURATOM/ENEA Fusion Association, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy)], E-mail: zucchetti@polito.it

    2007-10-15

    The possibility of clearance of vanadium-chromium-titanium (V-Cr-Ti) alloys is analysed. These alloys after their service in fusion power plants, have the potential to reach clearance if they are purified from activation products. The extraction part of the technological scheme for radiochemical separation of components of irradiated V-Cr-Ti alloy and their purification from metallic activation products, developed earlier, was tested for the first time in laboratory conditions using activated alloy specimens. The replacement of the acid reextraction of V with peroxide and of acid reextraction of Cr with alkaline improved characteristics of the extraction reprocessing. Duration of the V and Cr reextraction was shortened by about an order of magnitude, the output of these alloy components was increased, V purification from rare-earth metals became two times as great, and Cr decontamination from Co increased by two orders of magnitude. Activation of Be contaminated with trace quantities of uranium is an issue: estimation of Be activation in the blanket of the Power Plant Conceptual Study (PPCS) has suggested that traces of U impurity in Be should be removed - or substantially reduced - prior to use.

  12. Hydrogen embrittlement of vanadium alloys

    The mechanical properties of several vanadium alloys were measured with the hydrogen concentration high up to 113 mg/kg. The results showed that the alloys with low mechanical strength had better properties against hydrogen embrittlement. Oxygen in the alloy, especially that in the alloys with high strength, could enhance the hydrogen embrittlement. Mechanism analysis was given to show that the brittle fracture was mainly caused by intergranular failure. The effects of oxygen concentration and the strength of the alloy were both resulted from their contributions to the grain strength and the grain boundary strength

  13. Oxygen diffusion in vanadium-based alloys

    The experimental study of transport and equilibrium properties of oxygen in vanadium-based alloys was made by EMF measurements on solid electrolytic cells over the temperature range of 873 to 14230K. The oxygen diffusion in vanadium was not significantly modified by small additions of Ti, Cr, Ni, Nb and Ta. The increase in the activation energy for oxygen diffusion in the V-based alloys containing Cr, Ni, Nb and Ta probably reflects the effect of these substitutional solutes on the activity coefficient of oxygen. The oxygen activity was increased by the addition of 1 at % of Cr, Ni and Nb, and decreased by the addition of Ti and Ta. However, the effects in the alloys containing Nb and Ta are very small

  14. Chemistry related to the procurement of vanadium alloys

    Smith, H.M.; Chung H.M.; Tsai, H.C. [Argonne National Lab., IL (United States)

    1997-08-01

    Evaluation of trace element concentrations in vanadium alloys is important to characterize the low-activation characteristics and possible effects of trace elements on the properties. Detailed chemical analysis of several vanadium and vanadium alloy heats procured for the Argonne vanadium alloy development program were analyzed by Johnson-Matthey (UK) as part of a joint activity to evaluate trace element effects on the performance characteristics. These heats were produced by normal production practices for high grade vanadium. The analyses include approximately 60 elements analyzed in most cases by glow-discharge mass spectrometry. Values for molybdenum and niobium, which are critical for low-activation alloys, ranged from 0.4 to 60 wppm for the nine heats.

  15. Development of fabrication technology for low activation vanadium alloys as fusion blanket structural materials

    High purity vanadium alloy products, such as plates, wires and tubes, were fabricated from reference high-purity V-4Cr-4Ti ingots designated as NIFS-HEAT, by using technologies applicable to industrial scale fabrication. Impurity behavior during breakdown, and its effect on mechanical properties were investigated. It was revealed that mechanical properties of the products were significantly improved by the control of Ti-C, N, O precipitation induced during the processes. (author)

  16. Recycling of vanadium alloys in fusion reactors

    The feasibility of reprocessing a vanadium alloy after its use as a structural material in a fusion reactor, in order to enable its subsequent hands-on recycling within the nuclear industry, has been determined. For less neutron-exposed components, clearance of materials has also been considered. A conceptual model for the radiochemical processing of the alloy has been developed and tested experimentally. Using di-2-ethyl-hexyl-phosphoric acid it is possible to purify the components of the V-Cr-Ti alloy after its exposure in a fusion reactor down to the required level of activation product concentrations

  17. Impact property of low-activation vanadium alloy after laser welding and heavy neutron irradiation

    Nagasaka, Takuya, E-mail: nagasaka@nifs.ac.jp [National Institute for Fusion Science, Toki, Gifu (Japan); The Graduate University for Advanced Studies, Toki, Gifu (Japan); Muroga, Takeo [National Institute for Fusion Science, Toki, Gifu (Japan); The Graduate University for Advanced Studies, Toki, Gifu (Japan); Watanabe, Hideo [Research Institute for Applied Mechanics, Kyushu University, Kasuga (Japan); Miyazawa, Takeshi [The Graduate University for Advanced Studies, Toki, Gifu (Japan); Yamazaki, Masanori [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki (Japan); Shinozaki, Kenji [Department of Mechanical System Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima (Japan)

    2013-11-15

    Weld specimens of the reference low activation vanadium alloy, NIFS-HEAT-2, were irradiated up to a neutron fluence of 1.5 × 10{sup 25} n m{sup −2} (E > 0.1 MeV) (1.2 dpa) at 670 K and 1.3 × 10{sup 26} n m{sup −2} (5.3 dpa) at 720 K in the JOYO reactor in Japan. The base metal exhibited superior irradiation resistance with the ductile-to-brittle transition temperature (DBTT) much lower than room temperature (RT) for both irradiation conditions. The weld metal kept the DBTT below RT after the 1.2 dpa irradiation; however, it showed enhanced irradiation embrittlement with much higher DBTT than RT after the 5.3 dpa irradiation. The high DBTT for the weld metal was effectively recovered by a post-irradiation annealing at 873 K for 1 h. Mechanisms of the irradiation embrittlement and its recovery are discussed, based on characterization of the radiation defects and irradiation-induced precipitation.

  18. Dynamics of data flows on the low-activated vanadium alloy for thermonuclear power engineering (analysis of four international data bases)

    The paper presents the results of scientometric analysis of data flows in the International Data Bases SCOPUS, INSPEC, INIS, MSCI over a period since 1971 to 2014 on low-activated vanadium alloys suitable for operation as structural materials under extremely hard conditions in the future fusion reactors. The data on the dynamics of publications and contributions in them from the scientists of different countries have been obtained. The types and languages of publications have been identified. The analysis shows that investigations on the low-activated vanadium alloys are of current importance

  19. Thermodynamics of oxygen in solid solution in vanadium and niobium--vanadium alloys

    A thermodynamic study was made of the vanadium-oxygen and niobium-vanadium-oxygen systems utilizing the solid state galvanic cell technique. Investigations were made with a ThO2/Y2O3 electrolyte over the temperature ranges 700 to 12000C (973 to 1473 K) for the binary system and 650 to 11500C (923 to 1423 K) for the ternary system. The activity of oxygen in vanadium obeys Henry's law for the temperatures of this investigation for concentrations up to 3.2 at. percent oxygen. For higher concentrations the activity coefficient shows positive deviations from Henry's law. The terminal solubility of oxygen in vanadium was determined. The activity of oxygen in Nb--V alloys obeys Henry's law for the temperatures of this study for oxygen concentrations less than approximately 2 at. percent. For certain Nb/V ratios Henry's law is obeyed for concentrations as high as 6.5 at. percent oxygen. First order entropy and enthalpy interaction coefficients have been determined to describe the effect on the oxygen activity of niobium additions to vanadium-rich alloys with dilute oxygen concentrations. Niobium causes relatively small decreases in the oxygen activity of V-rich alloys and increases the oxygen solubility limit. Vanadium additions to Nb-rich alloys also increases the oxygen solubility and causes substantial decreases in the dilute solution oxygen activities. The change in the thermodynamic properties when molecular oxygen dissolves in vanadium and niobium--vanadium alloys and the equilibrium oxygen pressure over the binary and ternary systems were also determined

  20. Characterization for Fusion Candidate Vanadium Alloys

    T. Muroga; T. Nagasaka; J. M. Chen; Z. Y. Xu; Q. Y. Huang; y. C. Wu

    2004-01-01

    This paper summarizes recent achievements in the characterization of candidate vanadium alloys obtained for fusion in the framework of the Japan-China Core University Program.National Institute for Fusion Science (NIFS) has a program of fabricating high-purity V-4Cr4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various research groups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricated a new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogen embrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that the NIFS-HEAT maintained the ductility to relatively high hydrogen levels.The comparison of the data with those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should be responsible for the increased resistance to hydrogen embrittlement.Based on the chemical analysis data of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of Plasma Physics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The results showed that the low level of Co dominates the activity up to 50 years followed by a domination of Nb or Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of which are thought to have been introduced via cross-contamination into the alloys from the molds used should be crucial for reducing further the activation.

  1. Irradiation creep of vanadium-base alloys

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  2. Vanadium

    ÇEVİK, Sabri

    2014-01-01

    Vanadium corrosion and oxidation resistant transition metal exhibits common oxidation states ranging from +2 to +5. Vanadium and vanadium compounds are used in production of nonferrous alloy steel, semiconductors, and photographic developing materials. Many vanadium compounds act as catalyst in many industrial process like production of sulfuric acid and many organic compounds. Foods are main source for humans and animals. VO31− ions predominate in extracellular body fluids whereas VO2+ ions ...

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

    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 the atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates

  4. Corrosion behavior of vanadium alloys in flowing lithium

    Corrosion data are presented for several vanadium alloys exposed to flowing lithium at 427, 482 and 5380C. The corrosion behavior was evaluated by measuring weight change. Metallographic results and data on the nonmetallic element transfer in lithium-exposed specimens are also presented. The influence of alloy composition and exposure conditions on the corrosion behavior of vanadium alloys is discussed. (orig.)

  5. Activity of hydrogen in metal-hydrogen systems: strontium, thorium-nitrogen, and vanadium alloys

    The dissolution of H gas has been studied using pressure-composition isotherms in Sr, Th-N and V alloys containing either Nb, Cr or Ti. Direct H equilibrium vapor pressure measurements were performed in the Sr-H and Th-N-H systems at 973 to 11730K and 623 to 11230K, respectively. Isopiestic solubility was used to measure the H equilibrium pressures for the V alloys at 223 to 4730K. In all the alloys studied, the reaction of hydrogen with the metal phase was exothermic and hydrogen followed Sieverts' law over a considerable range of hydrogen concentration. The enthalpy of solution of H in the Sr and the enthalpy of formation of ThNH/sub x/ are -14.3 +- 1.2 kcal;/mol H and -16.3 +- 1.5 kcal/mol H2, respectively. Enthalpies of solution of H for the V alloys ranged from -8.0 to -10.5 +- 0.3 kcal/mol H. Additions of T to V dramatically enhanced the isopiestic solubility of H, Cr significantly reduced the solubility and Nb moderately increased the solubility. Sieverts' law behavior for H in the V alloys showed that substitutional atoms did not act as deep traps for H

  6. Vanadium alloys - overview and recent results

    Muroga, T.; Nagasaka, T.; Abe, K.; Chernov, V. M.; Matsui, H.; Smith, D. L.; Xu, Z.-Y.; Zinkle, S. J.

    2002-12-01

    This paper reviews recent progress in research on vanadium alloys with emphasis on V-4Cr-4Ti as a reference composition. New high purity V-4Cr-4Ti ingots and products (NIFS-HEATs) were made. The improved purity of the alloys made a practical demonstration of enhanced feasibility of recycling as a method of handling after use in fusion reactors. Significant progress has been made in the understanding of physical metallurgy of V-4Cr-4Ti and effects of O, N and C on the alloy properties such as low and high temperature mechanical properties, welding properties and low temperature irradiation effects, by means of including the comparison of various large heats and model alloys with different impurity levels. The effects of other trace impurities on some of the properties are also discussed. Other current efforts to characterize V-4Cr-4Ti, to improve its properties and to explore advanced vanadium alloys are reviewed. Issues remaining for the future investigations are discussed.

  7. Vanadium-base alloys for fusion reactor applications

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined

  8. Vanadium

    Although a relatively abundant element, vanadium occurs only rarely in sufficient concentration to be worked commercially. In most cases, vanadium is produced as a co-product of some other element, most commonly iron. The principal ore deposits of vanadium occur in titaniferous magnetites that have been formed by magnetic segregation. Important commercial deposits of vanadium also occur associated with uranium, and with phosphate deposits. The principal uses of vanadium are in the production of special purpose, particularly high-strength low-alloy steels, in the manufacture of titanium alloys, and as a catalyst, notably in the manufacture of sulphuric acid. Small quantities of vanadium, often in combination with niobium, are added to steel to bring about toughening through grain refinement, and increased tensile strength through precipitation hardening. Known world reserves of vanadium are very large and fully adequate to meet any foreseeable demand. By far the largest known deposits of vanadium occur in South Africa. Many other similar deposits are known, but are only exploited in the USSR and China. The present total world demand for vanadium amounts to about 40 000 tons of metal annually and this is produced primarily in four countries, South Africa, the USSR, the People's Republic of China and the United States of America, in that order. South Africa is the principal vanadium producing country in the world, supplying vanadium in various forms. Vanadium has a very low and non-accumulative toxicity; recovery plants can be operated in such a manner to ensure no air or steam pollution results

  9. Development of briquettes for steel semidirect alloying with vanadium

    Based on ferrovanadium type FS40Vd and vanadium-containing containing converter slag the briquettes for alloying steels type 20-60 KhN with vanadium were developed and commercially used. Component content ratios and desired granulometric composition which allow to recover 89-94 % V from a converter slag are determined. The master alloy with silicon concentration ranged within 45-50 % is considered to be optimum, bearing in mind the melting temperature, the density of initial and final alloys, aluminium consumption and vanadium yield from briquettes. 7 refs.; 3 figs.; 4 tabs

  10. Semidirect alloying of steel with vanadium-containing exothermic briquettes

    Exothermic vanadium-containing briquettes are designed and tested in practice. Briquettes allow introducing up to 0.15% V into the steel, vanadium recovery from converter slag being reached 94%. Ladle steel alloying by the briquettes decreases cost by 2-4% and aluminium consumption by a factor of 1.5. The briquettes consist of converter slag (15,54-19,65%V2O5), master alloy (6.18-6.95%V), aluminium and dolomite. 1 ref

  11. Research and development on vanadium alloys for fusion applications

    Zinkle, S.J.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Matsui, H.; Abe, K. [Tohoku Univ. (Japan); Smith, D.L. [Argonne National Lab., IL (United States); Osch, E. van [NERF, Petten (Netherlands); Kazakov, V.A. [RIAR, Dimitrovgrad (Russian Federation)

    1998-03-01

    The current status of research and development on unirradiated and irradiated V-Cr-Ti alloys intended for fusion reactor structural applications is reviewed, with particular emphasis on the flow and fracture behavior of neutron-irradiated vanadium alloys. Recent progress on fabrication, joining, oxidation behavior, and the development of insulator coatings is also summarized. Fabrication of large (>500 kg) heats of V-4Cr-4Ti with properties similar to previous small laboratory heats has now been demonstrated. Impressive advances in the joining of thick sections of vanadium alloys using GTA and electron beam welds have been achieved in the past two years, although further improvements are still needed.

  12. Determination of vanadium in double alloys by complete differential spectrophotometry

    A differential method to determine vanadium in the binary alloys (V-Cr, V-Al, V-Re) is described. The method is based on the formation of different-ligand vanadium complexes with o-nitrophenylfluorone and diantipyrylmethane. The complex is formed in pH range from 2.0 to 2.5 and extracted by the mixture of 93 vol.% chloroform and 7 vol.% amyl alcohol. Accidental and systematic errors of determination are calculated

  13. Thermodynamics of oxygen in solid solution in vanadium and niobium--vanadium alloys

    A thermodynamic study has been made of the vanadium--oxygen and niobium--vanadium--oxygen systems utilizing the solid state galvanic cell technique. Investigations were made with a ThO2/Y2O3 electrolyte over the temperature ranges 700 to 12000C (973 to 1473 K) for the binary system and 650 to 11500C (923 to 1423 K) for the ternary system. The activity of oxygen in vanadium obeys Henry's law for the temperatures of this investigation for concentrations up to 3.2 at.% oxygen. For higher concentrations the activity coefficient shows positive deviations from Henry's law. The oxygen activity, entropy, and enthalpy can be described over the entire composition range by interstitial solution theories when it is assumed that second nearest neighbor oxygen--oxygen interaction energies are of the same magnitude as the first nearest neighbor interactions. The terminal solubility of oxygen in vanadium was determined

  14. U.S. Contribution 1994 Summary Report Task T12: Compatibility and irradiation testing of vanadium alloys

    Vanadium alloys exhibit important advantages as a candidate structural material for fusion first wall/blanket applications. These advantages include fabricability, favorable safety and environmental features, high temperature and high wall load capability, and long lifetime under irradiation. Vanadium alloys with (3-5)% chromium and (3-5)% titanium appear to offer the best combination of properties for first wall/blanket applications. A V-4Cr-4Ti alloy is recommended as the reference composition for the ITER application. This report provides a summary of the R ampersand D conducted during 1994 in support of the ITER Engineering Design Activity. Progress is reported for Vanadium Alloy Production, Welding, Physical Properties, Baseline Mechanical Properties, Corrosion/Compatibility, Neutron Irradiation Effects, Helium Transmutation Effects on Irradiated Alloys, and the Status of Irradiation Experiments. Separate abstracts have been prepared for individual reports from this publication

  15. Development of high purity vanadium alloys for fusion reactors

    Vanadium alloys are most attractive candidate materials for liquid Li self-cooled blanket system of fusion reactors. This paper summarizes the program and its activities of the NIFS (National Institute for Fusion Science), Japan for developments of high purity V-4Cr-4Ti alloys. The results from NIFS-Heats show various benefits by reducing the level of oxygen. Significant improvement of the impact properties of the welded joint by reducing oxygen level is one of examples in recent studies. Collaboration is in progress, in which those heats are being characterized by a number of research groups including Japanese universities, and international collaboration partners in the US, Russia and China. The impact tests of irradiated specimens are in progress for further investigation. Significant progress has been made recently on the insulator ceramic coating in static conditions in the Japan-USA Cooperation Program. The understanding on the condition of in-situ CaO coating in liquid Li was enhanced. Based on these achievements, a flowing loop test is being planned to investigate the effects of temperature gradient and Li chemistry. (Y. Tanaka)

  16. Development of low activation vanadium steel for fusion applications

    Proposed fusion reactors may enjoy significant advantages regarding public safety and waste disposal over current fission reactors. Neutron activation to the structural materials can be minimized by the appropriate choice of alloys. Unfortunately, commercially developed alloys for high temperature applications become activated with neutron absorption leading to sometimes very long decay chains. The present paper discusses the results of a new ''low activation'' ferritic alloy (UCVS-1) developed at UCLA. This new alloy, which contains vanadium instead of molybdenum for high temperature strength, shows very promising combinations of strength, ductility and low long-term radioactive products. It is shown in this paper that the strength and ductility of UCVS-1 are comparable to 2 1/4 Cr-1 Mo up to 4000C, achieving significant advantages regarding safety and radioactive waste disposal

  17. Sputtered Clusters from Niobium-Vanadium Alloys

    Schou, Jørgen; Hofer, W. O.

    1982-01-01

    A series of Nb&z.sbnd;V alloys have been irradiated by 6 keV argon ions. Homonuclear and heteronuclear clusters emitted from these alloys have been studied by means of post-ionization and/or secondary ion mass spectrometry. The intensity of clusters of atomic masses up to approximately 300 amu wa...

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

    The reliable information on design and material properties of self-cooled Li-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/m2 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 1026 m-2, irradiation temperature range of 500-523 C) are presented and analyzed as a basis for such loop development. (orig.)

  19. Sputtered Clusters from Niobium-Vanadium Alloys

    Schou, Jørgen; Hofer, W. O.

    1982-01-01

    A series of Nb&z.sbnd;V alloys have been irradiated by 6 keV argon ions. Homonuclear and heteronuclear clusters emitted from these alloys have been studied by means of post-ionization and/or secondary ion mass spectrometry. The intensity of clusters of atomic masses up to approximately 300 amu was...... related to the concentrations of Nb and V in the alloys. In addition, the behaviour of polyatomic cluster yields as a function of partial oxygen pressure was studied. At partial pressures larger than approximately 10 6Torr, the yields decreased with increasing partial pressures. By inclusion of the post...

  20. Delayed failure of vanadium-hydrogen alloys

    Group Va refractory metals (Ta, V and Nb) are known to be embrittled in tension by hydrogen at low temperatures, but no work has been reported on delayed failure. The high mobility of hydrogen in V at room temperature, up to 5 x 10-5 cm2/sec, would be expected to enhance hydrogen migration to regions of high stress and affect time-dependent fracture behaviour. The present work was performed to determine the role of hydrogen, in solution and/or as a hydride, in the room temperature delayed failure behaviour of vanadium. Specimens were dead-weight loaded at room temperature in a creep-rupture testing machine; time to rupture was determined as a function of stress intensity, which was calculated by standard ASTM methods for a double edge notched sheet. Results are reported and discussed. (author)

  1. Mechanical alloying process of vanadium powder with 1.7 wt.%Y addition

    Alloying process of vanadium-yttrium powders using mechanical alloying (MA) method was studied. Vanadium powder was compressed after 10 h MA, while yttrium powder was comminuted into small particles. Although yttrium powder was broken into small particles, yttrium scarcely dissolves into vanadium powder. Alloying of yttrium started after 20 h MA and finished after 40 h MA. Molybdenum particle, which came from milling vessels and balls, mixed into vanadium powder after 40 h MA and molybdenum started to dissolve into vanadium powder after 60 h MA. After 80 h MA, Y2O3 particles formed in vanadium powder. Oxygen required for the formation of Y2O3 particles was probably discharged from the vessel wall and balls after flaking of those surface layers. Since prolonged MA caused powder contamination, optimum MA time for making V-1.7Y alloy was 40 h.

  2. Activation analysis for different structural alloys considered for ITER

    Activation calculations have been made for the austentic steel 316SS, the ferritic alloy HT-9, the titanium alloy Ti6A14V, and the vanadium alloy V5Cr5Ti in a liquid metal (Na) design suggested recently for ITER. The calculations show that the vanadium alloy has the minimum short and long-term radioactivity and BHP. It also has the minimum decay heat at all the time. The titanium alloy has less radioactivity than the austenitic and this ferritic alloys. However, the decay heat of this alloy could exceed that of the conventional alloys

  3. Activation analyses for different fusion structural alloys

    The leading candidate structural materials, viz., the vanadium alloys, the nickel or the manganese stabilized austenitic steels, and the ferritic steels, are analysed in terms of their induced activation in the TPSS fusion power reactor. The TPSS reactor has 1950 MW fusion power and inboard and outboard average neutron wall loading of 3.75 and 5.35 MW/m2 respectively. The results shows that, after one year of continuous operation, the vanadium alloys have the least radioactivity at reactor shutdown. The maximum difference between the induced radioactivity in the vanadium alloys and in the other iron-based alloys occurs at about 10 years after reactor shutdown. At this time, the total reactor radioactivity, using the vanadium alloys, is about two orders of magnitude less than the total reactor radioactivity utilizing any other alloy. The difference is even larger in the first wall, the FW-vanadium activation is 3 orders of magnitude less than other alloys' FW activation. 2 refs., 7 figs

  4. Development of vanadium base alloys for fusion first-wall/blanket applications

    Vanadium alloys have been identified as a leading candidate material for fusion first-wall/blanket applications. Certain vanadium alloys exhibit favorable safety and environmental characteristics, good fabricability, high temperature and heat load capability, good compatibility with liquid metals and resistance to irradiation damage effects. The current focus is on vanadium alloys with (3-5)% Cr and (3-5)% Ti with a V-4Cr-4Ti alloy as the leading candidate. Preliminary results indicate that the crack-growth rates of certain alloys are not highly sensitive to irradiation. Results from the Dynamic Helium Charging Experiment (DHCE) which simulates fusion relevant helium/dpa ratios are similar to results from neutron irradiated material. This paper presents an overview of the recent results on the development of vanadium alloys for fusion first wall/blanket applications

  5. Development of laser welding techniques for vanadium alloys

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-04-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Lasers do not require a vacuum (as do electron beam welders) and the welds they produce high depth-to-width ratios. Scoping with a small pulsed 50 J YAG laser indicated that lasers could produce successful welds in vanadium alloy (V-5%Cr-5%Ti) sheet (1 mm thick) when the fusion zone was isolated from air. The pulsed laser required an isolating chamber filled with inert gas to produce welds that did not contain cracks and showed only minor hardness increases. Following the initial scoping tests, a series of tests were preformed with a 6 kW continuous CO{sub 2} laser. Successful bead-on-plate welds were made on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys to depths of about 4 mm with this laser.

  6. Tensile properties of vanadium alloys irradiated at <430 degrees C

    Recent attention to vanadium alloys has focused on significant susceptibility to loss of work-hardening capability in irradiation experiments at <430 degrees C. An evaluation of this phenomenon was conducted on V-Ti, V-Cr-Ti, and V-Ti-Si alloys irradiated in several conventional and helium-charging irradiation experiments in the FFTF-MOTA, HFIR, and EBR-II. Work hardening capability and uniform tensile elongation appear to vary strongly from alloy and heat to heat. A strong heat-to-heat variation has been observed in V-4Cr-4Ti alloys tested, i.e., a 500-kg heat (No. 832665), a 100-kg heat (VX-8), and a 30-kg heat (BL-47). The significant differences in susceptibility to loss of work-hardening capability from one heat to another are estimated to correspond to a difference of ∼100 degrees C or more in minimum allowable operating temperature (e.g., 450 versus 350 degrees C)

  7. Disassembly of irradiated lithium-bonded capsules containing vanadium alloy specimens

    Tsai, H.; Strain, R.V.

    1996-04-01

    Capsules containing vanadium alloy specimens from irradiation experiments in FFTF and EBR-II are being processed to remove the lithium bond and retrieve the specimens for testing. The work has progressed smoothly.

  8. Microstructure and mechanical properties of vanadium alloys after thermomechanical treatments

    The results of investigation of dispersion strengthening effect on parameters of structural-phase states and characteristics of short-term strength and ductility of vanadium alloys of V–4Ti–4Cr, V–2.4Zr–0.25C, V–1.2Zr–8.8Cr and V–1.7Zr–4.2Cr–7.6W systems with different concentration of interstitial elements after optimized thermomechanical treatment mode were summarized. It was shown that for effective realization of dispersion strengthening by Orowan-type mechanism at least 25–50% of the initial volume fraction of coarse particles should be transformed into fine-disperse state and redistributed over the volume of material

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

    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.

  10. Technical assessment of vanadium-base alloys for fusion reactor applications. Volume I. Assessment of data base, needs and recommendations. Final report

    A technical assessment of vanadium and vanadium-base alloys for fusion reactor applications has been carried out. The major objective of this assessment was the development of an informed basis of understanding of the chemical, mechanical, and irradiation response characteristics of vanadium alloys. Efforts were focused on several separate, but interrelated, program tasks. First, a detailed review and analysis of the pertinent technical literature was carried out. Properties which were emphasized were those believed to be most important to making judgments of the viability of vanadium alloys as candidate fusion reactor strucutral materials. The next task reviewed the technical data bases, and methods and assumptions related to their use, which have been factored into life/performance analyses. The critical data gaps/priority needs necessary for these analyses are documented. Finally, criteria are suggested, and test/evaluation procedures recommended, pertinent to judging relative performance levels of vanadium alloys during future alloy development activities. Compositional and metallurgical variables recommended for investigation during such future activities are also presented

  11. The development of low-activation alloys at ORNL

    The objective of this program is to advance the technology of reduced-activation ferritic steels, austenitic stainless steels, and vanadium alloys to the point where these alloys could be considered as the structural material for fusion reactors in preference to the conventional high-activation alloys; and develop alloys to meet US Nuclear Regulatory Commission 10CFR61 guidelines for shallow land burial. 20 figs., 1 tab

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

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-04-01

    V-4Cr-4-Ti alloy has been recently selected for use in the manufacture of a portion of the DIII-D Radiative Divertor modification, as part of an overall DIII-D vanadium alloy deployment effort developed by General Atomics (GA) in conjunction with the Argonne and Oak Ridge National Laboratories (ANL or ORNL). The goal of this work is to produce a production-scale heat of the alloy and fabricate it into product forms for the manufacture of a portion of the Radiative Divertor (RD) for the DIII-D tokamak, to develop the fabrications technology for manufacture of the vanadium alloy radiative Divertor components, and to determine the effects of typical tokamak environments in the behavior of the vanadium alloy. The production of a {approx}1300-kg heat of V-4Cr-4Ti alloy is currently in progress at Teledyne Wah Chang of Albany, oregon (TWCA) to provide sufficient material for applicable product forms. Two unalloyed vanadium ingots for the alloy have already been produced by electron beam melting of raw processes vanadium. Chemical compositions of one ingot and a portion of the second were acceptable, and Charpy V-Notch (CVN) impact test performed on processed ingot samples indicated ductile behavior. Material from these ingots are currently being blended with chromium and titanium additions, and will be vacuum-arc remelted into a V-4Cr-4Ti alloy ingot and converted into product forms suitable for components of the DIII-D RD structure. Several joining methods selected for specific applications in fabrication of the RD components are being investigated, and preliminary trials have been successful in the joining of V-alloy to itself by both resistance and inertial welding processes and to Inconel 625 by inertial welding.

  13. Self-healing electrical insulating coating processes for vanadium alloy-lithium systems

    The existing technological approaches for the formation of nitride- and oxide-based self-healing electrical insulating coatings for vanadium alloy-lithium systems are considered. The results of the property study of coatings applied from liquid lithium containing Al, N, Si, B additions on various modes are considered. The formation conditions of AlN-based coatings with scale specific electrical resistivity (∼50 Ω m) on the V-4Ti-4Cr vanadium alloy are determined. The results of formation and stability research of coatings on the V-4Ti-4Cr vanadium alloy in convectional and forced circulating lithium with Al and N additions in the homogeneous and heterogeneous lithium systems are discussed

  14. Alloyed White Cast Iron With Precipitates of Spheroidal Vanadium Carbides VC

    M. Kawalec

    2012-12-01

    Full Text Available The paper presents the results of tests on the spheroidising treatment of vanadium carbides VC done with magnesium master alloy and mischmetal. It has been proved that the introduction of magnesium master alloy to an Fe-C-V system of eutectic composition made 34% of carbides crystallise in the form of spheroids. Adding mischmetal to the base alloy melt caused 28% of the vanadium carbides crystallise as dendrites. In base alloy without the microstructure-modifying additives, vanadium carbides crystallised in the form of a branched fibrous eutectic skeleton.Testing of mechanical properties has proved that the spheroidising treatment of VC carbides in high-vanadium cast iron increases thetensile strength by about 60% and elongation 14 - 21 times, depending on the type of the spheroidising agent used.Tribological studies have shown that high-vanadium cast iron with eutectic, dendritic and spheroidal carbides has the abrasive wearresistance more than twice as high as the abrasion-resistant cast steel.

  15. Effect of vanadium on nitrate reductase activity in tomato leaves

    J. Buczek

    2015-01-01

    The activity of nitrate reductase in cell-free extracts from tomato leaves is completely inhibited by 100 μM NaVO3 or VOCl2. In experiments in vivo vanadium ions inhibit the activity of the enzyme in 50 to 60 per cent. Addition of l mM vanadium to the medium on which tomato seedlings are grown causes after 24 h almost complete inhibition of nitrate reductase activity in cell-free extracts of the enzyme. Inhibition with vanadium may be abolished in experiments in vitro if the extract is treate...

  16. Reference vanadium alloy V-4Cr-4Ti for fusion application

    Vanadium alloys exhibit important advantages as a candidate structural material for fusion first-wall/blanket applications. These advantages include high temperature and high wall load capability, favorable safety and environmental features, resistance to irradiation damage, and alloys of interest are readily fabricable. A substantial data base has been developed on laboratory-scale heats of V-Ti, V-Cr-Ti and V-Ti-Si alloys before and after irradiation. Investigations in recent years have focused primarily on compositions of V-(0--15)Cr-(0--20)Ti (0--1)Si. Results from these investigations have provided a basis for identifying a V-4Cr-4Ti alloy as the US reference vanadium alloy for further development. Major results obtained on one production-scale heat and three laboratory heats with compositions of V-(4--5)Cr-(4--5)Ti are presented in this paper. Properties measured were input properties, tensile properties, creep, and radiation effects

  17. Measurement and analysis of radioactivity induced in steels and a vanadium alloy by 14-MeV neutrons

    Richter, D.; Forrest, R. A.; Freiesleben, H.; Kovalchuk, Va. D.; Kovalchuk D, Vi.; Markovskij, D. V.; Seidel, K.; Tereshkin, V. I.; Unholzer, S.

    2000-12-01

    Samples of the structural material of the International Thermonuclear Experimental Reactor (SS316), of the low-activation steels MANET and F82H, and of the vanadium alloy V4Ti4Cr were irradiated with D-T fusion neutrons. The radioactivities induced were determined after irradiation several times during decay by γ-spectroscopy. The results were analysed with the European Activation System (EASY-97). In order to validate EASY-97, the total activities of the samples are compared, and ratios of calculated-to-experimental values for the individual activities are derived and discussed.

  18. Hydrogen transport and embrittlement for palladium coated vanadium-chromium-titanium alloys

    Vanadium based alloys have been identified as a leading candidate material for fusion first-wall blanket structure application because they exhibit favorable safety and environmental characteristics, good fabricability, potential for high performance and long-time operation lifetime in a fusion environment. As part of a study of the thermodynamics, kinetics and embrittlement properties of hydrogen in vanadium based alloys, experiments were conducted to determine the rate of hydrogen transport through the vanadium reference alloys, V-7.5Cr-15Ti and V-4Cr-4Ti, and to determine these alloys' hydrogen embrittlement, they were exposed to hydrogen pressures of 3 and 300 kPa (0.03--3 atm) at temperatures between 380 and 475 C. To facilitate hydrogen entry and egress, tubes of these alloys were coated with palladium on the inside and outside faces. Observed permeabilities were 0.015 to 0.065 micromoles/(m2sPa0.5) for the V-7.5Cr-15Ti alloy and 0.02 to 0.05 micromoles/m2sPa0.5 for the V-4Cr-4Ti alloy depending on the quality of the coat and the operating temperature. At 1.7 atm hydrogen, V-7.5Cr-15Ti embrittled at temperatures below 380 C while V-4Cr-4Ti embrittled around 330 C

  19. Prospects and problems using vanadium alloys as a structural material of the first wall and blanket of fusion reactors

    Vanadium-based alloys are most promising as low activation structural materials for DEMO. It was previously established that high priority is to be given to V-alloys of the V-Ti-Cr system as structural materials of a tritium breeding blanket and the first wall of a fusion reactor. However, there is some uncertainty in selecting a specific element ratio between the alloy components in this system. This is primarily explained by the fact that the properties of V-alloys are dictated not only by the ratio between the main alloying elements (here Ti and Cr), but also by impurities, both metallic and oxygen interstitials. Based on a number of papers today one can say that V-Ti-Cr alloys with insignificant variations in the contents of the main constituents within 5-10 mass% Ti and 4-6 mass% Cr must be taken as a base for subsequent optimization of chemical composition and thermomechanical working. However, the database is obviously insufficient to assess the ecological acceptability (activation), physical and mechanical properties, corrosion and irradiation resistance and, particularly, the commercial production of alloys. Therefore, there is a need for comprehensive studies of promising V-alloys, namely V-4Ti-4Cr and V-10Ti-5Cr. (orig.)

  20. Magnetic properties and fine structure of Fe-Co alloys with vanadium and chromium additions

    Dzhavadov, D.M.; Tyapkin, Yu.D. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))

    1982-11-01

    Magnetic properties of alloys iron-cobalt, iron-cobalt-vanadium, iron-cobalt-chromium have been investigated. Measurements of permeability, coercive force Hsub(c), B/sub 25/ and B/sub 100/ magnetic saturation on alloy samples on which electrical resistance previously is measured and fine crystalline structure is studied by the methods of transmission electron microscopy, diffusion scattering of X rays and electrons and NGR. Comparison of properties and structure makes possible to bind Hsub(c), B permeability values with such structure features as a long-range order of B2 type, short-range decomposition order and Cottrell clouds formation in vanadium containing alloys and a complex short-range order in chromium-containing alloys.

  1. Peculiarities of helium bubble formation and helium behavior in vanadium alloys of different chemical composition

    Staltsov, M.S.; Chernov, I.I.; Kalin, B.A.; Oo, Kyi Zin; Polyansky, A.A.; Staltsova, O.S.; Aung, Kyaw Zaw [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow (Russian Federation); Chernov, V.M.; Potapenko, M.M. [A.A. Bochvar High-Technology Research Institute of Inorganic Materials, Moscow (Russian Federation)

    2015-06-15

    The influence of alloying of vanadium by Ti and Fe on helium bubble formation, gaseous swelling and helium release peculiarities is investigated by means of transmission electron microscopy and helium thermal desorption spectrometry (HTDS). The samples were irradiated by 40 keV He{sup +} ions up to a fluence of 5 ⋅ 10{sup 20} m{sup −2} at 293 and 923 K. It is found that large faceted pores/bubbles are formed in pure vanadium and it has the highest gaseous swelling. Alloying by any used quantity of Ti (from 0.1 up to 10 wt.%) or Fe (from 1 up to 10 wt.%) essentially decreases the helium swelling. The effect of alloying of vanadium by Ti on the bubble sizes and the helium swelling is nonmonotonic. The density of bubbles increases significantly and their sizes and swelling grow monotonically with increasing the Fe content in vanadium. With low-temperature helium implantation, alloying of V by Ti shifts the HTDS peaks to higher temperatures and the temperatures of peaks are decreased with increasing the Fe concentration. A significant portion of the helium releases in a high-temperature area beyond the main peak temperatures in the HTDS spectra. It is assumed that this is caused by formation of helium bubbles on the surfaces of incoherent particles of secondary phases (oxides, nitrides), having high binding energies with these particles.

  2. Investigation on Retention and Release Behaviors of Hydrogen and Helium in Vanadium Alloy

    Liu Xiang; Tsuyoshi Yamada; Yuji Yamauchi; Yuko Hirohata; Tomoaki Hino; Nobuaki Noda

    2005-01-01

    Vanadium alloy is proposed as an attractive candidate for first wall and blanketstructural material of fusion reactors. The retention and release behaviors of hydrogen and heliumin vanadium alloy may be an important issue. In the present work, 1.7 keV deuterium and 5keV helium ions are respectively implanted into V-4Cr-4Ti and V-4Ti at room temperature. Theretention and release of deuterium and helium are measured with thermal desorption spectroscopy(TDS). When the helium ion fluence is larger than 3 × 1017 He/cm2, the retained helium saturateswith a value of approximately 2.5 × 1017 He/cm2. However, when the ion fluence is 1 × 1019 D/cm2,the hydrogen saturation in vanadium alloy does not take place. Experimental results indicatesthat hydrogen and helium retention in vanadium alloy may lead to serious problems and specialattention should be paid when it is applied to fusion reactors.

  3. Peculiarities of helium bubble formation and helium behavior in vanadium alloys of different chemical composition

    The influence of alloying of vanadium by Ti and Fe on helium bubble formation, gaseous swelling and helium release peculiarities is investigated by means of transmission electron microscopy and helium thermal desorption spectrometry (HTDS). The samples were irradiated by 40 keV He+ ions up to a fluence of 5 ⋅ 1020 m−2 at 293 and 923 K. It is found that large faceted pores/bubbles are formed in pure vanadium and it has the highest gaseous swelling. Alloying by any used quantity of Ti (from 0.1 up to 10 wt.%) or Fe (from 1 up to 10 wt.%) essentially decreases the helium swelling. The effect of alloying of vanadium by Ti on the bubble sizes and the helium swelling is nonmonotonic. The density of bubbles increases significantly and their sizes and swelling grow monotonically with increasing the Fe content in vanadium. With low-temperature helium implantation, alloying of V by Ti shifts the HTDS peaks to higher temperatures and the temperatures of peaks are decreased with increasing the Fe concentration. A significant portion of the helium releases in a high-temperature area beyond the main peak temperatures in the HTDS spectra. It is assumed that this is caused by formation of helium bubbles on the surfaces of incoherent particles of secondary phases (oxides, nitrides), having high binding energies with these particles

  4. Investigations on the Oxidation of Iron-chromium and Iron-vanadium Molten Alloys

    Wang, Haijuan

    2010-01-01

    With the progress of high alloy steelmaking processes, it is essential to minimize the loss of valuable metals, like chromium and vanadium during the decarburization process, from both economic as well as environmental view points. One unique technique to realize this aim, used in the present work, is the decarburization of high alloy steel grades using oxygen with CO2 in order to reduce the partial pressure of oxygen. In the present work, the investigation on the oxidation of iron-chromium a...

  5. Neutron metrology in the HFR. Irradiation of vanadium alloys. Experiment R204-7/8/9 (VABONA)

    The irradiation experiment R204-7/8/9 is part of a material research program VABONA in which the radiation damage is investigated of different vanadium alloys. The experiment deals with the irradiation of vanadium specimens α-implanted at the cyclotron in Ispra. The irradiation has been performed in a SIENA capsule in the HFR Petten at three different temperatures (873, 973 and 1073 K). The irradiation took place in position C5 during seven HFR operating cycles. The target damage level was 5 dpa (displacements per atom). This report presents the final neutron metrology results obtained from activation monitors in the three specimen holders, coded as R204-7/8/9. Data about the number of displacements per atom are also included. The main results of the thermal and fast neutron fluence measurements are presented. (orig.)

  6. Development of electrically insulating self-healing coatings in vanadium alloys for lithium fusion reactor

    Problems on electrically insulating self-healing coatings (SHC) on vanadium alloys for lithium fusion reactor systems are considered. In particular, the SHC stability and radiation resistance in lithium and effect of magnetic field on the efficiency of the TNR lithium systems are studied. New technological methods for application of self-healing coatings and study on their properties are developed. The vanadium-lithium materials testing in pile loops for solution of the above problems under conditions of the lithium TNR is described

  7. The vanadium alloys technological and corrosion studies in construction and operation of liquid metal facilities for fusion reactor

    The vanadium-lithium test facility has been constructed to carry out corrosion tests of vanadium alloys in lithium flow, to evaluate the welding procedures and to develop electrically insulating coatings for lithium self-cooled blanket application. The corrosion tests were performed in a nonisothermal lithium flow with the flow rate up to 1 m/s at temperatures in the range 450-700 C. The results of development of the electrically insulating coatings are presented. The achieved specific resistance of AlN based coatings is 30-40 Ω m. The results of electron-beam and argon tungsten-arc welding methods are presented for welding sheets, rods and pipes of V-Ti-Cr type alloys. Solution of the vanadium alloys and vanadium alloys-stainless steels welding problems enabled construction of a liquid metal system satisfying all the necessary requirements. (orig.)

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

    Gruber, E.E.; Galvin, T.M.; Chopra, O.K. [Argonne National Lab., IL (United States)

    1998-09-01

    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.

  9. Microstructural and microchemical evolution in vanadium alloys by heavy ion irradiation

    Sekimura, Naoto; Kakiuchi, Hironori; Shirao, Yasuyuki; Iwai, Takeo [Tokyo Univ. (Japan)

    1996-10-01

    Microstructural and microchemical evolution in vanadium alloys were investigated using heavy ion irradiation. No cavities were observed in V-5Cr-5Ti alloys irradiated to 30 dpa at 520 and 600degC. Energy dispersive X-ray spectroscopy analyses showed that Ti peaks around grain boundaries. Segregation of Cr atoms was not clearly detected. Co-implanted helium was also found to enhance dislocation evolution in V-5Cr-5Ti. High density of matrix cavities were observed in V-5Fe alloys irradiated with dual ions, whereas cavities were formed only around grain boundaries in single ion irradiated V-5Fe. (author)

  10. Preliminary studies of vanadium-base alloys intended for use in fabrication of cans for fast reactors

    Preliminary research has been carried out on a series of vanadium-based alloys: V, 0.5 per cent Si; V, 5 per cent Ca; V, 5 per cent Mo; V, 5 per cent Nb; V, 2 per cent Zr; V, 20 per cent Ti; V, 10 per cent Al; V, 10 per cent Sn and v, 10 per cent Ti liable to be used as canning material in fast reactors. The transformation by forging at about 1000 deg. C and rolling between 200 deg. C and room temperature is satisfactory for all types of alloys except V with 10 per cent Sn and V with 10 per cent Al. The mechanical properties deduced from tensile strength tests carried out on alloy samples annealed 1 hour at 1050 deg. C in a vacuum show that, generally speaking, the addition elements lead to an improvement in these properties as compared to those of pure vanadium. After undergoing corrosion tests in a liquid sodium loop purified by a cold trap, the alloys become brittle at room temperature. Only the vanadium containing 20 per cent Ti keeps its plastic properties. These alloys are covered by a layer of vanadium carbide VC. After undergoing treatment in a liquid sodium loop purified by a hot trap, all the alloys keep their good mechanical characteristics. The surface layer with which they are covered is composed of two vanadium carbides VC and γVC, and a vanadium sub-oxide VO0.9. (author)

  11. Response of unirradiated and neutron-irradiated vanadium alloys to Charpy-impact loading

    The ductile-brittle transition temperature (DBTT) was determined by Charpy-impact impact tests for dehydrogenated (<30 appm H) and hydrogenated (400--1200 appm H) V-7.2Cr-14.5Ti, V-9.9Cr-9.2Ti, V-13.5Cr-5.2Ti, V-17.7Ti, V-9.2Cr-4.9Ti, V-9.0Cr-3.2Fe-1.2Zr, V-3.1Ti-0.5Si, V-4.1Cr-4.3Ti, V-4.6Ti, and V-2.5Ti-1.0Si alloys. The DBTT was also determined for the V-13.5Cr-5.2Ti, V-9.2Cr-4.9Ti, V-7.2Cr-14.5Ti, and V-17.7Ti alloys after neutron irradiation at 420 and 600 degrees C to 41--44 atom displacements per atom. The DBTTs determined for these vanadium alloys show that a vanadium alloy containing Cr and/or Ti and Si alloying additions to be used as a structural material in a fusion reactor should contain 3--11 wt % total alloying addition for maximum resistance to hydrogen- and/or irradiation-induced embrittlement. 4 refs., 3 figs., 2 tabs

  12. Hydrogen transport and embrittlement for palladium coated vanadium-chromium-titanium alloys

    As part of a study of the thermodynamics, kinetics and embrittlement properties of hydrogen in vanadium based alloys, experiments were conducted to determine the rate of hydrogen transport through the vanadium reference alloys, V-7.5Cr-15Ti and V-4Cr-4Ti, and to determine these alloys' hydrogen embrittlement, they were exposed to hydrogen pressures of 3 and 300 kPa (0.03-3 atm) at temperatures between 380 and 475 C. To facilitate hydrogen entry and egress, tubes of these alloys were coated with palladium on the inside and outside faces. Observed permeabilities were 0.015 to 0.065 μmol/(m2 s Pa0.5) for the V-7.5Cr-15Ti alloy and 0.02 to 0.05 μmol/(m2 s Pa0.5) for the V-4Cr-4Ti alloy depending on the quality of the coat and the operating temperature. At 1.7 atm hydrogen, V-7.5Cr-15Ti embrittled at temperatures below 380 C while V-4Cr-4Ti embrittled around 330 C. (orig.)

  13. Mechanical properties of neutron irradiated vanadium alloys under liquid sodium environment

    Full text of publication follows: Vanadium alloys are candidate materials for fusion reactor blanket structural materials, but its knowledge about the mechanical properties at high temperatures during neutron irradiation is limited and there are uncertainties that may have influenced the results such as the interstitial impurity content of specimens. The objective of this study is to investigate the mechanical properties and microstructural changes of the high-purified V-4Cr-4Ti alloys, NIFS-HEAT2 during neutron irradiation. In this study, tensile test, Charpy impact test and microstructural observation were done for V-4Cr-4Ti alloys and vanadium binary alloys. Small sized tensile specimens, 1.5 Charpy V-notched specimens and TEM specimens of highly purified V-4Cr-4Ti alloys, NIFS-Heat and vanadium binary alloys were irradiated in Joyo in the temperature range from 450 deg. C to 650 deg. C with a damage level from 1 to 5 dpa. In the irradiation experiment, we have developed Na-enclosed irradiation rig in Joyo in order to equalize the irradiation temperature of large scale specimens and prevent the invasion of interstitial impurities from the circumstance in irradiation rig during irradiation for irradiation specimens. After dismantling the Na-enclosed capsule and cleaning the surface of specimens, tensile tests at room temperature, Charpy impact tests and TEM observation were performed. Irradiation hardening and reduction of ductility for NIFS-Heat alloys could be seen at 450 deg. C irradiation in tensile tests, but the destructive loss of plasticity could not be in any vanadium specimens even at 450 deg. C irradiation. Results of Charpy impact test showed that the amounts of upper shelf energy of NIFS-heat specimens irradiated at 450 deg. C and 600 deg. C were about 0.1-0.2 J at room temperature and brittle behavior could not be seen from load displacement relationship and SEM observation of fracture surface. From the TEM observation of NIFS-Heat alloys

  14. Proceedings of the 2. workshop on vanadium alloy development for fusion

    Osch, E.V. van [ed.

    1996-10-01

    From 20 to 22 May 1996 the Second IEA Vanadium Alloy Development for Fusion Workshop was held at the Netherlands Energy Research Foundation, ECN in Petten. Twenty three experts from the European Union, Japan, the Russian Federation and the United States exchanged results and analyses of completed experiments and discussed the program planning. The manufacturing of half-finished products and the optimization of subsequent heat treatments were presented and discussed in the first session. The problems and solutions to joining vanadium alloy half-finished products by welding and brazing have been addressed in another session. Corrosion and compatibility properties have been evaluated in a different session together with coating requirements. Several sessions were devoted to the effects of radiation on the mechanical properties, especially toughness, of vanadium alloys. Also the role of the transmutation product helium, in particular its introduction into specimens, was evaluated. The respective plans of the four parties for continuation of the ongoing research and development programs have been discussed with the emphasis on avoiding duplications in the area of radiation experiments. The critical issues were identified and the related priorities discussed in the time frame set by the schedule for the building of ITER test modules and with the long term DEMO requirements in mind. (orig.).

  15. Proceedings of the 2. workshop on vanadium alloy development for fusion

    From 20 to 22 May 1996 the Second IEA Vanadium Alloy Development for Fusion Workshop was held at the Netherlands Energy Research Foundation, ECN in Petten. Twenty three experts from the European Union, Japan, the Russian Federation and the United States exchanged results and analyses of completed experiments and discussed the program planning. The manufacturing of half-finished products and the optimization of subsequent heat treatments were presented and discussed in the first session. The problems and solutions to joining vanadium alloy half-finished products by welding and brazing have been addressed in another session. Corrosion and compatibility properties have been evaluated in a different session together with coating requirements. Several sessions were devoted to the effects of radiation on the mechanical properties, especially toughness, of vanadium alloys. Also the role of the transmutation product helium, in particular its introduction into specimens, was evaluated. The respective plans of the four parties for continuation of the ongoing research and development programs have been discussed with the emphasis on avoiding duplications in the area of radiation experiments. The critical issues were identified and the related priorities discussed in the time frame set by the schedule for the building of ITER test modules and with the long term DEMO requirements in mind. (orig.)

  16. Development of laser welding techniques for vanadium alloys

    Strain, R.V.; Leong, K.H.; Smith, D.L. [Argonne National Laboratory, IL (United States)

    1996-10-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Bead-on-plate and butt welds were previously performed to depths of about 4 mm with a 6-kW CO{sub 2} laser on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys. These welds were made at a speed of 0.042 m/s using argon purging at a flow rate of 2.8 m{sup 3}/s. The purge was distributed with a diffuser nozzle aimed just behind the laser beam during the welding operation. The fusion zones of welds made under these conditions consisted of very fine, needle-shaped grains and were also harder than the bulk metal (230-270 dph, compared to {approx}180 dph for the bulk metal). A limited number of impact tests showed that the as-welded ductile-brittle transition temperatures (DBTT) was above room temperature, but heat treatment at 1000{degrees}C for 1 h in vacuum reduced the DBTT to <{minus}25{degrees}C. Activities during this reporting period focused on improvements in the purging system and determination of the effect of welding speed on welds. A 2-kW continuous YAG laser at Lumonics Corp. in Livonia, MI, was used to make 34 test welds for this study.

  17. Tensile properties of vanadium alloys irradiated at 200{degrees}C in the HFIR

    Chung, H.M.; Nowicki, L.; Smith, D.L. [Argonne National Lab., IL (United States)

    1997-08-01

    Vanadium alloys were irradiated in a helium environment to {approx}10 dpa at {approx}200{degrees}C in the High Flux Isotope Reactor (HFIR). This report presents results of postirradiation tests of tensile properties of laboratory heats of V-(1-18)Ti, V-4Cr-4Ti, V-8Cr-6Ti, V-9Cr-5Ti, V-3Ti-1Si, and V-3Ti-0.1C alloys. Because of significant loss of work-hardening capability, all alloys except V-18Ti exhibited a very low uniform plastic strain <1%. For V-Ti. The mechanism of the loss of work-hardening capability in the other alloys is not understood.

  18. Tensile properties of vanadium alloys irradiated at 200 degrees C in the HFIR

    Vanadium alloys were irradiated in a helium environment to ∼10 dpa at ∼200 degrees C in the High Flux Isotope Reactor (HFIR). This report presents results of postirradiation tests of tensile properties of laboratory heats of V-(1-18)Ti, V-4Cr-4Ti, V-8Cr-6Ti, V-9Cr-5Ti, V-3Ti-1Si, and V-3Ti-0.1C alloys. Because of significant loss of work-hardening capability, all alloys except V-18Ti exhibited a very low uniform plastic strain <1%. For V-Ti. The mechanism of the loss of work-hardening capability in the other alloys is not understood

  19. Hydrogen internal friction and interaction of solute atoms in niobium- and vanadium-based alloys

    A computer model has been proposed to be used to calculate the internal friction spectrum, caused by the ''diffusion under stress'' of hydrogen atoms in a solid solution with a b.c.c. lattice containing substitutional atoms. The model takes into account the long-range pair interaction of dissolved atoms. It is suggested that such interaction acts on diffusion by producing short-range order of mobile hydrogen atoms and by changing their energy. These changes occur in the tetrahedral (before the jump) as well as in the octahedral (at the saddle point of the diffusion barrier) interstitial sites and, therefore, produce local changes of the hydrogen diffusion activation energy (the activation energy of internal friction). The relaxation strength is calculated from the local fields of atomic displacements around every atom that participates in diffusion. The model has been used to study the nature of hydrogen relaxation in Ti- and Zr-containing Nb- and V-based alloys and to calculate the ''chemical'' interaction energy of the H(D)-Ti(Zr) pairs. It was shown that the hydrogen relaxation mechanism in Nb(V)-Ti(Zr)-H(D) alloys consists in diffusion under stress of hydrogen or deuterium atoms in the vicinity of single substitutional atoms at low concentration of substitutional atoms and high hydrogen or deuterium concentration, and in the vicinity of substitutional pairs - at high concentration of substitutional atoms and low hydrogen or deuterium concentration. The ''chemical'' interaction H(D)-Ti(Zr) in niobium and vanadium is stronger or is of the same order, as the strain-induced (elastic) interaction. (orig.)

  20. The creep- and creep-rupture-behavior of vanadium-base-alloys

    In connection with the development of vanadium-base-alloys as potential cladding-material for Fast Breeder fuel elements different melts of the following composition-groups were tested: 1) V-Ti-Nb (3-20% Ti, 0-20% Nb); 2) V-Zr-Cr, V-Zr-Nb (2-3% Zr, 2-15% Cr, 15% Nb); 3) V-Ti-Cr, V-Ti-Nb-Cr (0-5% Ti, 2-13% Cr, 5-10% Nb); 4) V-Ti-Mo, V-Al (5% Ti, 5% Mo, 0,2% Al); 5) V-Ti-Ge (3% Ti, 1-4% Ge); 6) V-Ti-Si, V-Ti-Nb-Si (3% Ti, 1-1,5% Si, 5-15% Nb); 7) Rein-Vanadium (O2=220-800 ppm). The creep- and creep-rupture-behavior is summarized and described comparatively. In the temperature range 650-8750C the long-time-strength behavior up to 43,000 hours and the creep constants have been determined. The outstanding influence of the titanium content, the strong matrix-hardening effect of the niobium and the interaction between titanium and the interstitial impurities have been established. It is also shown that the oxygen content plays a special role in improving greatly the creep and creep-rupture-behavior, both in pure vanadium and in alloys with titanium and silicon. The second edition (1989) of this report includes as appendix a short contribution to vanadium-alloys as a potential fusion-reactor material. (orig./MM)

  1. Insulating Coating Development for Vanadium Alloys. Phase I Technical Report

    Self-cooled liquid-lithium/vanadium blanket offers many advantages for fusion power systems. Liquid metals moving through a magnetic field are subjected to magnetohydrodynamic (MHD) effects that can increase the pressure drop and affect the flow profiles and heat transfer. Insulating coatings are required to eliminate this effect. Based on the thermodynamic stability data five different coatings were selected PVD and CVD processes were developed to deposit these coatings. All coatings have resistivities much higher than the minimum required. Liquid lithium testing at Argonne National Laboratory indicates that one of the coatings showed only partial spalling. Thus, further refinement of this coating has significant potential to satisfy the requirements for Li/V blanket technology

  2. Local magnetic moment and hyperfine field in hydrogenated iron and iron-vanadium alloy

    Elzain, M.E.; Yousif, A.A. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.

    1994-11-01

    The local magnetic moment {mu} and hyperfine field B{sub hf} at Fe and V sites in hydrogenated iron and iron-vanadium were calculated using the discrete variational method. The variations in {mu} and B{sub hf} with H occupation of the octahedral (O) site were considered. It was found that when H occupies the O site neighbouring an Fe atom, both local moment and hyperfine field at this atom decrease linearly with increasing number of H atoms. The rate of decrease is larger for Fe in iron as compared to iron in vanadium. On the other hand, when H resides at an O site next neighbouring an Fe atom, whether in iron metal or in iron-vanadium, the Fe magnetic moment increases slowly, while the hyperfine field remains almost constant. The V moment in iron, which is negative ({approx} -0.83 {mu}{sub B}), becomes less negative ({approx} -0.30 {mu}{sub B}) as H occupies the neighboring O sites, whereas slight changes occur ({approx} -0.88 {mu}{sub B}) when H is at the next neighbouring O site. The net effect of H on Fe in iron is to decrease the average magnetic moment at a rate of {approx} 1.2 {mu}{sub B} per H/Fe for low H content. On the other hand, the average Fe moment in an iron-vanadium alloy increases if H resides at O sites which are immediate neigbours of V and next neighbours of Fe. This may explain the development of a magnetic state on hydrogenation of Fe-V alloys, which is exhibited by the specific heat and susceptibility measurements. The changes in the isomer shift were found to agree with experimental trends. (orig.)

  3. Effect of vanadium neighbors on the hyperfine properties of iron-vanadium alloys

    Elzain, M., E-mail: elzain@squ.edu.om; Yousif, A.; Gismelseed, A.; Al Rawas, A.; Widatallah, H.; Bouziane, K.; Al-Omari, I. [College of Science, Sultan Qaboos University, Physics Department (Oman)

    2008-06-15

    The electronic and magnetic structures of Fe-V alloys are calculated using the discrete-variational and full-potential linearized-augmented-plane wave methods. The derived hyperfine properties at Fe sites are studied against the number of Fe atoms in the neighbouring shells. As expected the magnetic hyperfine field depends strongly on the number of Fe atoms in the first and second shells of neighbours while its dependence on the variation of atoms in the third shell is weak. The calculated distribution of the magnetic hyperfine fields at the Fe sites, are compared to the experimental data of Krause et al. (Phys Rev B 61:6196-6204, 2000). The contact charge densities and the magnetic moments are also calculated. It was found that the contact charge density increases with increasing V contents and this leads to negative isomer shift on addition of V.

  4. Effect of helium on tensile properties of vanadium alloys

    Chung, H.M.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

    1997-08-01

    Tensile properties of V-4Cr-4Ti (Heat BL-47), 3Ti-1Si (BL-45), and V-5Ti (BL-46) alloys after irradiation in a conventional irradiation experiment and in the Dynamic Helium Charging Experiment (DHCE) were reported previously. This paper presents revised tensile properties of these alloys, with a focus on the effects of dynamically generated helium of ductility and work-hardening capability at <500{degrees}C. After conventional irradiation (negligible helium generation) at {approx}427{degrees}C, a 30-kg heat of V-4Cr-4Ti (BL-47) exhibited very low uniform elongation, manifesting a strong susceptibility to loss of work-hardening capability. In contrast, a 15-kg heat of V-3Ti-1Si (BL -45) exhibited relatively high uniform elongation ({approx}4%) during conventional irradiation at {approx}427{degrees}C, showing that the heat is resistant to loss of work-hardening capability.

  5. Mechanical behavior of tungsten-vanadium-lanthana alloys as function of temperature

    Palacios García, Teresa; Pastor Caño, Jose Ignacio; Aguirre Cebrian, Maria Vega; Martin Sanz, Antonia; Monge, M. A.; A. Muñoz; Pareja, R.

    2011-01-01

    This study is presented of: The Fifteenth International Conference on Fusion Reactor Materials (ICFRM-14) was held October 16–22, 2011, at the Charleston Marriott Hotel in Charleston, South Carolina. The mechanical behavior of three tungsten (W) alloys with vanadium (V) and lanthana (La₂O₃) additions (W–4%V, W–1%La2O3, W–4%V–1%La₂O₃) processed by hot isostatic pressing (HIP) have been compared with pure-W to analyze the influence of the dopants. Mechanical characterization was performed by...

  6. Surface cracking of tungsten-vanadium alloys under transient heat loads

    Kameel Arshad

    2015-07-01

    Full Text Available To evaluate high heat load performance of tungsten-vanadium (W-V alloys as a potential candidate for plasma facing materials of fusion devices, the target materials with three different V concentrations (1, 5 and 10 wt% are exposed to thermal shock loading. The alloys are fabricated by cold isostatic pressing and subsequently sintered in a vacuum furnace. Thereafter, they are exposed to different high heat flux densities ranging from 340 to 675 MW/m2 for single shot of 5 ms duration in an intense electron beam test facility. The alloys with lowest V concentration (1 wt% are highly damaged in form of seriously cracking. The ones with intermediate V content (5 wt% has shown comparatively better performance than both highest and lowest V contents alloys. The results indicate that improved mechanical properties and reduced thermal conductivity due to V addition comprehensively affect the cracking behavior of W-V alloy under transient thermal shock.

  7. Tensile properties of vanadium alloys irradiated at <430{degrees}C

    Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1997-08-01

    Recent attention to vanadium alloys has focused on significant susceptibility to loss of work-hardening capability in irradiation experiments at <430{degrees}C. An evaluation of this phenomenon was conducted on V-Ti, V-Cr-Ti, and V-Ti-Si alloys irradiated in several conventional and helium-charging irradiation experiments in the FFTF-MOTA, HFIR, and EBR-II. Work hardening capability and uniform tensile elongation appear to vary strongly from alloy and heat to heat. A strong heat-to-heat variation has been observed in V-4Cr-4Ti alloys tested, i.e., a 500-kg heat (No. 832665), a 100-kg heat (VX-8), and a 30-kg heat (BL-47). The significant differences in susceptibility to loss of work-hardening capability from one heat to another are estimated to correspond to a difference of {approx}100{degrees}C or more in minimum allowable operating temperature (e.g., 450 versus 350{degrees}C).

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

    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.

  9. Impact properties of vanadium-base alloys irradiated at < 430 C

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys

  10. Impact properties of vanadium-base alloys irradiated at < 430 C

    Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Recent attention to vanadium-base alloys has focused on the effect of low-temperature (<430 C) neutron irradiation on the mechanical properties, especially the phenomena of loss of work-hardening capability under tensile loading and loss of dynamic toughness manifested by low impact energy and high ductile-brittle-transition temperature (DBTT). This paper summarizes results of an investigation of the low-temperature impact properties of V-5Ti, V-4Cr-4Ti, and V-3Ti-Si that were irradiated in several fission reactor experiments, i.e., FFTF-MOTA, EBR-II X-530, and ATR-A1. Irradiation performance of one production-scale and one laboratory heat of V-4C-4Ti and one laboratory heat of V-3Ti-Si was the focus of the investigation. Even among the same lass of alloy, strong heat-to-heat variation was observed in low-temperature impact properties. A laboratory heat of V-4Cr-4Ti and V-3Ti-1Si exhibited good impact properties whereas a 500-kg heat of V-4Cr-4Ti exhibited unacceptably high DBTT. The strong heat-to-heat variation in impact properties of V-4Cr-4Ti indicates that fabrication procedures and minor impurities play important roles in the low-temperature irradiation performance of the alloys.

  11. Feasibility of conducting a dynamic helium charging experiment for vanadium alloys in the advanced test reactor

    Tsai, H.; Gomes, I.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1996-10-01

    The feasibility of conducting a dynamic helium charging experiment (DHCE) for vanadium alloys in the water-cooled Advanced Test Reactor (ATR) is being investigated as part of the U.S./Monbusho collaboration. Preliminary findings suggest that such an experiment is feasible, with certain constraints. Creating a suitable irradiation position in the ATR, designing an effective thermal neutron filter, incorporating thermocouples for limited specimen temperature monitoring, and handling of tritium during various phases of the assembly and reactor operation all appear to be feasible. An issue that would require special attention, however, is tritium permeation loss through the capsule wall at the higher design temperatures (>{approx}600{degrees}C). If permeation is excessive, the reduced amount of tritium entering the test specimens would limit the helium generation rates in them. At the lower design temperatures (<{approx}425{degrees}C), sodium, instead of lithium, may have to be used as the bond material to overcome the tritium solubility limitation.

  12. Fine structure and resistance to fracture of low-alloyed steel with vanadium and boron

    An attempt to evaluate the effect of recovery recrystallization and precipitation processes of dispersion phases on the nature of heat-treating steel resistance to fracture is made. A low-alloy steel of industrial melting with the following content of components, weight %: C-0.18; Mn-1.4; Si-0.3; V-0.06; B-0.003; Al-0.04 and Ti-0.015 has been chosen. It is shown that vanadium carbide precipitation during tempering essentially contributes to the weakening processes. The main contribution to strength is made by the most dispersive carbide phase with the dimensions less than 0.03 mkm delaying weakening during tempering

  13. Ultra-fine ferrite grain refinement by static re-crystallization of hot rolled vanadium micro-alloyed steels

    The phenomenon of ultrafine-grain refinement of ferrite during transformational grain refinement (TGR) followed by static re-crystallization of vanadium micro-alloyed steels was studied. A substantial grain refinement (2.8 mu m) was attained during TGR process by rolling at 900 deg. C. Cold rolling with 70% of reduction introduced strain, utilized for re-crystallization during annealing at different temperatures. Electron Backscattered Diffraction (EBSD) technique was employed to quantify the low angle grain boundaries (LAGB) and high angle grain boundaries (HAGB) spacings and results were correlated with hardness drops during annealing process. At higher annealing times and temperatures the vanadium precipitates restricted the process of grain growth probably due to effective dispersion strengthening. The abnormal grain growth during annealing, predicted previously for niobium steels, found absent in the present vanadium microalloyed steels. (author)

  14. Effect of Cr and Ti contents on the recovery, recrystallization, and mechanical properties of vanadium alloys

    Gubbi, A.N.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    A series of vacuum-anneals at temperatures from 900 to 100{degrees}C for 1 to 4 h was carried out on small heats of vanadium alloys with Cr and Ti contents ranging from 2 to 6wt. %. The alloys examined on this work were V-3Cr-3Ti, V-4Cr-4Ti, V-5Cr-5Ti, V-6Cr-3Ti, and V-6Cr-6Ti. Optical miscroscopy, TEM, and microhardness testing were conducted. Variation in Cr and Ti over the range of 3 to 6 wt% had no discernible effect on recovery/recrystallization behavior. The hardness of both recovered and recrystallized structures increased with total (CR + Ti) content. In order to study the effect of Cr and Ti content on mechanical properties, Charpy impact testing and tensile testing were carried out on small heats of compositional variants. The V-4Cr-4Ti-Si alloy, in a fully recrystallized conditions, exhibited a high level of resistance to cleavage failure with a DBTT at {approx} 190{degrees}C. The alloy containing higher concentrations of Cr and Ti, in a fully recrystallized condition, exhibited a DBTT around -100{degrees}C, whereas the V-3Cr-3Ti alloy failed by pure ductile shear at liquid nitrogen temperature without any ductile-to-brittle transition. Tensile testing was conducted on SS-3 tensile specimens punched from 0.762-mm-thick plates of V-3Cr-3Ti and V-6Cr-6Ti. The tests were done in air at temperature at strain rates ranging from 10{sup -3} to 2x10{sup -1}/s. For V-6Cr-6Ti, both the 0.2% yield stress (YS) and the ultimate tensile strength (UTS) were higher than those for V-3Cr-3Ti at all strain rates. Both YS and UTS showed a similiar trend in incremental increase with strain rate for the two alloys. In the same token, both alloys exhibited an identical behavior of almost no change in uniform and total elongation up to a strain rate of 10{sup -1}/s and a decrease with further increase in strain rate.

  15. Structure and properties of a layered steel/vanadium alloy/steel composite prepared by high-pressure torsion

    Nikulin, S. A.; Rogachev, S. O.; Rozhnov, A. B.; Khatkevich, V. M.; Nechaikina, T. A.; Morozov, M. V.

    2016-04-01

    The microstructure and hardness of a layered steel 08Kh17T/V-10Ti-5Cr/steel 08Kh17T composite, which was prepared by torsion under a high hydrostatic pressure at temperatures of 20, 200, and 400°C, have been studied. Severe plastic deformation under used conditions is shown to provide good joining of layers, which is accompanied by their substantial hardening (from 2.0 to 3.5 times). During deformation at temperatures of 20 and 200°C, fragmentation of the vanadium alloy layer into thinner layers is observed; at 400°C, mainly a plane interface between the vanadium alloy and the steel layers is formed.

  16. Effect of neutron irradiation on the tensile properties and microstructure of several vanadium alloys

    Braski, D.N.

    1986-01-01

    Specimens of V-15Cr-5Ti, VANSTAR-7, and V-3Ti-1Si were encapsulated in TZM tubes containing /sup 7/Li to prevent interstitial pickup and irradiated in FFTF (MOTA experiment) to a damage level of 40 dpa. The irradiation temperatures were 420, 520, and 600/sup 0/C. For a better simulation of fusion reactor conditions, helium was preimplanted in some specimens using a modified version of the ''tritium trick.'' The V-15Cr-5Ti alloy was most susceptible to irradiation hardening and helium embrittlement, followed by VANSTAR-7 and V-3Ti-1Si. VANSTAR-7 exhibited a relatively high maximum void swelling of approx.6% at 520/sup 0/C while V-15Cr-5Ti and V-3Ti-1Si had values of less than 0.3% at all three temperatures. The V-3Ti-1Si clearly outperformed the other two vanadium alloys in resisting the effects of neutron irradiation.

  17. Tensile properties of vanadium alloys irradiated at 390{degrees}C in EBR-II

    Chung, H.M.; Tsai, H.C.; Nowicki, L.J. [Argonne National Lab., IL (United States)] [and others

    1997-08-01

    Vanadium alloys were irradiated in Li-bonded stainless steel capsules to {approx}390{degrees}C in the EBR-II X-530 experiment. This report presents results of postirradiation tests of tensile properties of two large-scale (100 and 500 kg) heats of V-4Cr-Ti and laboratory (15-30 kg) heats of boron-doped V-4Cr-4Ti, V-8Cr-6Ti, V-5Ti, and V-3Ti-1Si alloys. Tensile specimens, divided into two groups, were irradiated in two different capsules under nominally similar conditions. The 500-kg heat (No. 832665) and the 100-kg heat (VX-8) of V-4Cr-4Ti irradiated in one of the subcapsules exhibited complete loss of work-hardening capability, which was manifested by very low uniform plastic strain. In contrast, the 100-kg heat of V-4Cr-4Ti irradiated in another subcapsule exhibited good tensile properties (uniform plastic strain 2.8-4.0%). A laboratory heat of V-3Ti-1Si irradiated in the latter subcapsule also exhibited good tensile properties. These results indicate that work-hardening capability at low irradiation temperatures varies significantly from heat to heat and is influenced by nominally small differences in irradiation conditions.

  18. Tensile properties of vanadium alloys irradiated at 390 degrees C in EBR-II

    Vanadium alloys were irradiated in Li-bonded stainless steel capsules to ∼390 degrees C in the EBR-II X-530 experiment. This report presents results of postirradiation tests of tensile properties of two large-scale (100 and 500 kg) heats of V-4Cr-Ti and laboratory (15-30 kg) heats of boron-doped V-4Cr-4Ti, V-8Cr-6Ti, V-5Ti, and V-3Ti-1Si alloys. Tensile specimens, divided into two groups, were irradiated in two different capsules under nominally similar conditions. The 500-kg heat (No. 832665) and the 100-kg heat (VX-8) of V-4Cr-4Ti irradiated in one of the subcapsules exhibited complete loss of work-hardening capability, which was manifested by very low uniform plastic strain. In contrast, the 100-kg heat of V-4Cr-4Ti irradiated in another subcapsule exhibited good tensile properties (uniform plastic strain 2.8-4.0%). A laboratory heat of V-3Ti-1Si irradiated in the latter subcapsule also exhibited good tensile properties. These results indicate that work-hardening capability at low irradiation temperatures varies significantly from heat to heat and is influenced by nominally small differences in irradiation conditions

  19. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  20. Chlorine ions effect on photochemical activity of alcoholate complexes of vanadium

    Photochemical activity of vanadium complexes during alcogolate ion substitution by chlorine is studied. Using the method of electron spectroscopy and ESR photochemical transformations in alcohol solutions, containing alkoxides VO(OR)3, VO(OR)2Cl, VO(OR)Cl2 as well as VOCl3 with additions of HCl and LiCl, are investigated. It is shown that with the increase of chloride-ion concentration in solution the rate of all the stages of photochemical reduction of vanadium increases considerably. It is also found that photoreduction of vanadium (5) in the case of absence of chlorine ions ends at the stage of vanadium (3) complex formation, whereas when chlorine ions are present in solution the process proceeds further to the formation of divalent vanadium complexes

  1. Void structure and density change of vanadium-base alloys irradiated in the dynamic helium charging experiment

    Chung, H.M.; Nowicki, L.; Gazda, J. [Argonne National Lab., Chicago, IL (United States)] [and others

    1995-04-01

    The objective of this work is to determine void structure, distribution, and density changes of several promising vanadium-base alloys irradiated in the Dynamic Helium Charging Experiment (DHCE). Combined effects of dynamically charged helium and neutron damage on density change, void distribution, and microstructural evolution of V-4Cr-4Ti alloy have been determined after irradiation to 18-31 dpa at 425-600{degree}C in the DHCE, and the results compared with those from a non-DHCE in which helium generation was negligible.

  2. Structure and mechanical properties of the three-layer material based on a vanadium alloy and corrosion-resistant steel

    Nikulin, S. A.; Rozhnov, A. B.; Nechaikina, T. A.; Rogachev, S. O.; Zavodchikov, S. Yu.; Khatkevich, V. M.

    2014-10-01

    The quality of three-layer pipes has been studied; they are manufactured by hot pressing of a three-layer assembly of tubular billets followed by forging and cold rolling. The operating core is made from a V-4Ti-4Cr alloy. The protective claddings are made from corrosion-resistant steels of two grades, 08Kh17T and 20Kh13. The results of investigation into the structure and microhardness of the junction zone of steel and the vanadium alloy, which includes a contact zone and a transition diffusion layer, are reported. The 08Kh17T steel is shown to be a preferred cladding material.

  3. Thermodynamical study of the vanadium-hydrogen system. The hydrogen effect on the mechanical properties of V-4Cr-4Ti and V-5Cr-5Ti alloys

    In the framework of the international research programs on fusion reactors, the vanadium alloys are among the most appropriate candidate to constitute the first wall. The author deals with the specific alloys V-4Cr-4Ti and V-5Cr-5Ti and study the hydrogen diffusion. Experimental results show that the induced hydrogen concentration in the sample by diffusion is higher, for the same partial pressure of exposure, in the case of the alloy than for the pure vanadium. He shows that this result can be explained by the trapping for which the hydrogen is trapped by the titanium. (A.L.B.)

  4. Solidification microstructures and mechanical properties of high-vanadium Fe-C-V and Fe-C-V-Si alloys

    Fe-C-V and Fe-C-V-Si alloys of various C, V and Si compositions were investigated in this work. It was found that the phases present in both of these alloy systems were alloyed ferrite, alloyed cementite, and VCx carbides. Depending on the alloy composition the solidified microstructural constituents were granular pearlite-like, lamellar pearlite, or mixtures of alloyed ferrite + granular pearlite-like or granular pearlite-like + lamellar pearlite. In addition, it is shown that in Fe-C-V alloys the C/V ratio influences (a) the type of matrix, (b) the fraction of vanadium carbides, fv and (c) the eutectic cell count, NF. In Fe-C-V alloys, a relationship between the alloy content corresponding to the eutectic line was experimentally determined and can be described by Ce=7.91Ve-0.635 where Ce and Ve are the carbon and vanadium composition of the eutectic. Moreover, in the Fe-C-V alloys (depending on the alloy chemistry), the primary VCx carbides crystallize with non-faceted or non-faceted/faceted interfaces, while the eutectic morphology is non-faceted/non-faceted with regular fiber-like structures, or it possesses a dual morphology (non-faceted/non-faceted with regular fiber-like structures + non-faceted/faceted with complex regular structures). In the Fe-C-V-Si system, the primary VCx carbides solidify with a non-faceted/faceted interface, while the eutectic is non-faceted/faceted with complex regular structures. In particular, spiral eutectic growth is observed when Si is present in the Fe-C-V alloys. In general, it is found that as the matrix constituent shifts from predominantly ferrite to lamellar pearlite, the hardness, yield and tensile strengths exhibit substantial increases at expenses of ductility. Moreover, Si additions lead to alloy strengthening by solid solution hardening of the ferrite phase and/or through a reduction in the eutectic fiber spacings with a decrease in the alloy ductility.

  5. Solidification microstructures and mechanical properties of high-vanadium Fe-C-V and Fe-C-V-Si alloys

    Fras, E.; Kawalec, M. [AGH - University of Science and Technology, Reymonta 23, 30-059 Krakow (Poland); Lopez, H.F., E-mail: hlopez@uwm.edu [Materials Department, University of Wisconsin-Milwaukee, 3200 N. Cramer Street, Milwaukee, WI 53211 (United States)

    2009-10-25

    Fe-C-V and Fe-C-V-Si alloys of various C, V and Si compositions were investigated in this work. It was found that the phases present in both of these alloy systems were alloyed ferrite, alloyed cementite, and VC{sub x} carbides. Depending on the alloy composition the solidified microstructural constituents were granular pearlite-like, lamellar pearlite, or mixtures of alloyed ferrite + granular pearlite-like or granular pearlite-like + lamellar pearlite. In addition, it is shown that in Fe-C-V alloys the C/V ratio influences (a) the type of matrix, (b) the fraction of vanadium carbides, f{sub v} and (c) the eutectic cell count, N{sub F}. In Fe-C-V alloys, a relationship between the alloy content corresponding to the eutectic line was experimentally determined and can be described by C{sub e}=7.91V{sub e}{sup -0.635} where C{sub e} and V{sub e} are the carbon and vanadium composition of the eutectic. Moreover, in the Fe-C-V alloys (depending on the alloy chemistry), the primary VC{sub x} carbides crystallize with non-faceted or non-faceted/faceted interfaces, while the eutectic morphology is non-faceted/non-faceted with regular fiber-like structures, or it possesses a dual morphology (non-faceted/non-faceted with regular fiber-like structures + non-faceted/faceted with complex regular structures). In the Fe-C-V-Si system, the primary VC{sub x} carbides solidify with a non-faceted/faceted interface, while the eutectic is non-faceted/faceted with complex regular structures. In particular, spiral eutectic growth is observed when Si is present in the Fe-C-V alloys. In general, it is found that as the matrix constituent shifts from predominantly ferrite to lamellar pearlite, the hardness, yield and tensile strengths exhibit substantial increases at expenses of ductility. Moreover, Si additions lead to alloy strengthening by solid solution hardening of the ferrite phase and/or through a reduction in the eutectic fiber spacings with a decrease in the alloy ductility.

  6. Selective spectrophotometric determination of molybdenum(VI) and vanadium(V) with resacetophenone benzoic hydrazone in steels and alloys

    A spectrophotometric method for the determination of molybdenum(VI) and vanadium(V) using 2, 4-dihydroxyacetophenone benzoic hydrazone (RPBH) is reported. The reagent forms 1:1 yellow coloured complexes with Mo(VI) and V(V) at pH 3.5. The colour development of molybdenum complex is instantaneous and shows absorption maximum at 410nm. In the case of vanadium complex, maximum colour is developed after heating for 10 minutes on a water bath and show maximum absorption at 380nm. The molybdenum(VI) complex with a molar absorptivity of 3.6x103 l mol-1 cm-1 and Sandell's sensitivity of 0.02 μg/cm2, obeys Beer's law in the range 2.4 to 33.6 ppm. The vanadium(V) complex whose molar absorptivity and Sandell's sensitivity are 1.3x104 l mol-1 cm-1 and 0.004 μg/cm2 respectively, obeys Beer's law in the range 0.25 to 7.6 ppm. The effect of various diverse ions on the determination of the metal ions is studied. The method is applied for the determination of molybdenum and vanadium in steel and alloy samples. (author). 10 refs., 1 fig., 3 tabs

  7. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  8. Extraction-spectrophotometric determination of vanadium in stainless steel and nickel-base alloys with N-benzoyl-N-phenylhydroxylamine

    A simple, rapid, and accurate extraction-spectrophotometric methods has been developed for the determination of vanadium in stainless steel and Ni-base alloys. The procedure is as follows: Take 0.5 g of sample into a beaker and add 20 ml of aqua regia, then heat and dissolve it. Furthermore add 5 ml of perchloric acid, and heat until the sample is dissolved, and add 14 ml of sulfuric acid (1 + 1) and 5 ml of phosphoric acid. Continue heating untill fumes of sulfuric acid generate from it. Thereafter, transfer it with use of water into a polyethylene separating funnel, add 10 ml of hydrofluoric acid (46%) and dilute to 50 ml with water. Then, add 4 ml of iron (II) ammonium sulfate solution (10%) and mix it thoroughly. Allow to stand for two or three min, and add 10 ml of ammonium peroxy-sulfate solution (45%) and mix it thoroughly again. By this procedure vanadium is oxidized to vanadium (V) without any oxidation of chromium (III). Allow to stand for about five minutes. Then add exactly 20 ml of N-benzoyl-N-phenylhydroxylamine chloroform solution (0.1%) and shake it vigorously for two min. Then, determine vanadium by measuring absorbance at the wavelength of 530 nm against a chloroform reference. The interference of chromium can be eliminated by reduction to Cr (III) with iron (II) ammonium sulfate, while manganese and molybdenum do not interfere at 530 nm. In the determination of 100 μg vanadium, the following amounts of foreign ions are tolerated: Fe (III) and Ni 1 g, Cr (III) 500 mg, Al 200 mg, Mo (VI) 100 mg, Mn, Co (II), Ti (IV) and Nb (V) 50 mg, Si 20 mg, Cu 10 mg, Ta (V) and W (VI) 5 mg. (author)

  9. Textured tape substrates from binary copper alloys with vanadium and yttrium for the epitaxial deposition of buffer and superconducting layers

    Khlebnikova, Yu. V.; Rodionov, D. P.; Egorova, L. Yu.; Suaridze, T. R.

    2016-05-01

    The structure of tapes of binary Cu-0.6 wt % V and Cu-1 wt % Y alloys and texturing process of them in the course of cold deformation by rolling to 99% and subsequent recrystallizing annealing have been studied. The possibility of achieving the perfect cube texture in thin tapes made from binary copper-based alloys with vanadium and yttrium additions has in principle been shown. This opens the prospect of using them as substrates when manufacturing tapes of second-generation high-temperature superconductors. Optimum annealing conditions for the studied alloys have been determined, which have made it possible to produce the perfect biaxial texture with a content of cube {001} ± 10° grains on the surfaces of textured tapes of more than 95%.

  10. Effects of B, Fe, Gd, Mg, and C on the structure, hydrogen storage, and electrochemical properties of vanadium-free AB2 metal hydride alloy

    Highlights: → B, Fe, Gd, Mg, and C were studied as modifiers to the V-free AB2 MH alloys. → Mg and C show improvement in charge retention. → Fe, Gd, and B improve the low temperature performance. - Abstract: The structural, gaseous phase hydrogen storage, and electrochemical properties of a series of vanadium-free AB2 Laves phase based metal hydride alloys with various modifiers (Ti5Zr30Cr9Mn19Co5Ni32-xMx, M = B, Fe, Gd, Mg, and C) were studied. While B and Fe completely dissolve in the main AB2 phases, Gd, Mg, and C form individual secondary phases. The solubilities of Gd, Mg, and C in the AB2 phases are not detectable, 0.3 at.%, and very low, respectively. The C14 crystallite sizes, C15 phase abundances, and Zr7Ni10 phase abundances of modified alloys are larger than those of the base alloy. All modified alloys show decreases in plateau pressure, reversible gaseous phase storage capacity, formation activity, electrochemical capacity, and cycle life. A small amount of boron (0.2 at.%) and carbon in the alloy improve the half-cell high-rate dischargeability and bulk hydrogen diffusion. All modifiers, except for boron, reduce the surface exchange reaction current densities of the alloys. Both Mg and C show improvement in charge retention. Full-cell high-rate performance is improved by adding only a small amount of boron (0.2 at.%). Fe, Gd and 0.2 at.% of boron improve the low-temperature performance of the sealed batteries.

  11. 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

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

    2007-01-01

    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...

  12. Phase transitions in multicomponent interstitial alloys on the base of titanium and vanadium carbides

    Key words: interstitial alloys, nonstoichiometry, ordering, phase transitions, short-range and long-range order, neutron diffraction, X-ray crystallography, full-scale profile analysis, phase diagram, heat capacity. Objects of the research: phase formation and phase transitions in multicomponent systems on the base of nonstoichiometric titanium carbide and vanadium subcarbide. Aim of the research: study of phase transitions, regularities of ordered structures formation in nonstoichiometric interstitial alloys with one-, two-, three component metal and nonmetal sublattice on the base of titanium carbides and vanadium subcarbide. Methods of the research: neutron and X-ray structure analysis, full-scale profile analysis, calorimetric method. The obtained results and their novelty. By neutron diffraction in TiCx (0.59≤ x ≤0.66) the phase transition of order-order type is found caused by disappearance of distortions of the basic cubic lattice with conservation of the ordered distribution of metalloid atoms over octahedral interstitial positions; improved variant of a region of the TiCx phase diagram (0.59≤ x≤0.71) is offered. Partial replacement of carbon atoms by oxygen (O/Ti=0.08) is found to lead to change of the phase transition scheme in titanium carbide. Existence of trigonal ordered structure in TiCxNy (x=0.45†0.545; y=0.09†0.20) is discovered. Structure investigation showed the influence of nitrogen and hydrogen atoms on the existing cubic and trigonal ordered phases and on phase transition schemes in titanium carbide. Ordered phases are discovered and identified in titanium oxycarbonitrides; the scheme and temperature of phase transition are determined; structure of the ordered phase depends on nitrogen content: in TiC0.52O0.08N0.06 - trigonal (sp. gr. P31), in TiC0.48O0.08N0.10 - rhombohedral (sp. gr. R 3 bar m), in TiC0.31O0.08N0.29-cubic (sp. gr. Fd3m) ordered structures are formed. In Ti1-xZrxC0.65, Ti1-xCrxC0.7 and Ti0.8V0.2C0.62Hy a new

  13. Preliminary results on hydrogen permeation through vanadium alloy V-4Cr-4Ti in the conditions of reactor irradiation

    The objective of this work was the determination of hydrogen mass transfer parameters in vanadium alloy V-4Cr-4Ti > of reactor irradiation. The experiments were carried out on IVG.1M reactor of Kazakhstan Nuclear Center at fast neutrons flux of 1013 n/cm2s, thermal neutrons flux of 1014 n/cm2s. Determination of apparent diffusion coefficients was carded out by Dayness technique over the temperature range 873-973 K and inlet hydrogen pressures 0.07-0.2 torr. The thickness of the researched membrane shaped specimens was 1 and 5 mm. (author)

  14. Fabrication development and usage of vanadium alloys in DIII-D

    GA is procuring material, designing components, and developing fabrication techniques for use of V alloy into the DIII-D divertor as elements of the Radiative Divertor Project modification. This program was developed to assist in the development of low activation alloys for fusion use by demonstrating the fabrication and installation of V alloy components in an operating tokamak. Along with fabrication development, the program includes multiple steps starting with small coupons installed in DIII-D to measure the environmental effects on V. This is being done in collaboration with DOE Fusion Materials Program (particularly at ANL and ORNL). Procurement of the material has been completed; the world's largest heat of V alloy (1200 kg V-4Cr-4Ti) was produced and converted into various products. Manufacturing process is described and chemistry results presented. Research into potential fabrication methods is being performed. Joining of V alloys was identified as the most critical fabrication issue for its use in the Radiative Divertor program. Successful welding trials were done using resistance, friction, and electron beam methods; metallography and mechanical tests were done to evaluate the welds

  15. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter;

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...

  16. Volumetric changes during sintering of vanadium briquettes with niobium and molybdenum diselenides

    Volumetric changes which occur during sintering of vanadium with niobium and molybdenum diselenides are studied within 1200- 1500 deg C. It is shown that growth of briquettes during sintering of the above composites is due to preferential vanadium diffusion flow into the diselenide phase. Formation of the niobium- enriched (due to diselenide decomposition) alloy on the vanadiUm particle surface leads to a volumetric sintering activation- shrinkage

  17. Morphology and activity of vanadium-containing catalysts for the selective oxidation of benzene to maleic anhydride

    Dosumov, K.; Ergazieva, G. E.

    2012-11-01

    The morphology and activity of vanadium catalysts are studied using a number of physicochemical methods: electron microscopy, electron paramagnetic resonance, and infrared spectroscopy. It is found that the active agent of the conversion of benzene to maleic anhydride over modified vanadium catalysts is the V4+ ion in the vanadyl configuration.

  18. Vanadium Attack with Sigma Phase Occurrence in Fe-CrNi Alloy (ASTM A447)

    The vanadium attack of sigma phase occurrence in high chromium-nickel steel (ASTM A447) has been studied in fuel oil combustion environment. 80mole% V2O5-20mole% Na2SO4 was used as corrosive synthetic ash. Using metallograph and scanning electron microscope, various changes of microstructure of the specimen were observed in the corrosion process. The vanadium attack was affected by carbide rather than sigma phase in initial period of the test, but in the later period, sigma phase occurrence was more related for the attack. Vanadium attack seemed to be propagated along the boundary of matrix and sigma phase. Finally, sigma phase itself might be flaked out from grain boundary. However, stress corrosion cracking might be propagated through sigma phase which is brittle

  19. Effect of vanadium on the microstructures and mechanical properties of an Al–Mg–Si–Cu–Cr–Ti alloy of 6XXX series

    Highlights: •The shapes of Al3V and Al10V are like petal and coarse plate respectively. •Fine elliptical-shaped Al(VCrTi)Si phases are present when Al3V phases are added. •Coarse AlVMg phases are present when Al10V phases are added. •Larger as-cast grain refinement is carried out by Al3V phases rather than Al10V. •V improves the UTS and plasticity of the alloy only when Al3V phases are added. -- Abstract: Vanadium can be considered as a minor element to improve mechanical properties of wrought aluminium alloys by modifying their microstructures. However, so far, it is not widely used in wrought aluminium alloys due to its indissolubility during smelting and solidification. In the present work, Al–4 wt.% V master alloys were prepared with different solidification rates and these master alloys were introduced to a commercial Al–1.6Mg–1.2Si–1.1Cu–0.16Cr–0.03Ti (all in wt.%) wrought alloy to study the effect of vanadium on the microstructures and mechanical properties of this alloy. The results showed that the fast solidification rate resulted in the formation of petal-like shaped Al3V phase in Al–4 wt.% V master alloy, while the slow solidification rate resulted in the formation of Al10V phase with coarse plate shape. The addition of Al3V phases into the experimental alloy not only promotes the formation of a fine, equiaxed as-cast grain structure, but also inhibits the recrystallisation nucleation and grain growth during hot extrusion and subsequent T6 heat treatment. In this case, the main vanadium phase in this alloy is the metastable and fine Al(VCrTi)Si phase with elliptical morphology and relatively high vanadium content. And the Al(VCrTi)Si phases developed from Al3V phases could pin the movement of dislocations and impede recrystallisation nucleation and growth, resulting in the improvement of mechanical properties. In the experimental alloy with the addition of Al10V phases, the stable AlVMg phase and Al10V phase with angular shape are

  20. 可视滴定法测定铝钒中间合金中的钒时称样量和滴定液浓度的优化%Optimization of the Sampling and the Titration Concentration of Vanadium in the Determination of Vanadium in Aluminium-Vanadium Master Alloy by Visual Titration

    付二红; 蒙益林; 汪磊

    2013-01-01

    The correlation between the sampling and the titration concentration of vanadium in the determination of vanadium in aluminium-vanadium master alloy by visual titration was explored.The influence of aluminium substrate on the determination of vanadium content was investigated,the result indicated that the aluminium substrate could not affect the vanadium determination.The concentration of the vanadium was usually 50%-60%,there was no experimental sample in which vanadium content less than 50% or higher than 60.5%.It was necessary to simulate the sample of the aluminium-vanadium master alloy by adding vanadium standards without the matching of the substrate.According to the chemical reaction laws,the test specimens with different content of vanadium were chosen,the sampling and the titration concentration of vanadium were optimized.The appropriate relationship of the concentration of ferrous ammonium sulphate solution and the volume of titrant was defined.%用可视滴定法测定铝钒中间合金中的钒时,对称样量和硫酸亚铁铵滴定液浓度的关系进行了探讨.实验发现,基体铝对于铝钒合金中钒的测定无影响.常见的铝钒合金范围为50%~60%,低于50%和高于标准上限0.5%钒含量的合金没有实验样品,通过向样品溶液中加入钒标准溶液可模拟铝钒合金试样.依据化学分析等物质量反应定律,选择不同钒含量的试验样品,对钒的称样量和滴定液浓度进行优化,确定了硫酸亚铁铵滴定液的浓度与滴定液消耗体积的合适关系.

  1. The active component of vanadium-molybdenum catalysts for the oxidation of acrolein to acrylic acid

    The catalytic properties of the vanadium-molybdenum oxide system were investigated in the oxidation of acrolein to acrylic acid. The active component of the catalyst is the compound VMo3O11, the maximum amount of which is observed at a content of 7-15 mole% V2O4. The compound VMo3O11 is formed in the thermodecomposition of silicomolybdovanadium heteropoly acids or isopoly compounds, reduced with respect to vanadium, and contains V4+ and Mo6+. The optimum treatment for the formation of this compound is treatment in the reaction mixture at 400 degrees C

  2. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    Tomashchuk, I., E-mail: iryna.tomashchuk@u-bourgogne.fr; Grevey, D.; Sallamand, P.

    2015-01-12

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution.

  3. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution

  4. Drawing up of a procedure for vanadium determination in mussels using the neutron activation analysis method

    This work establishes an adequate procedure for obtaining reliable results for determination of vanadium in mussels, leg by leg by the neutron activation analysis (NAA), viewing the posterior application on the bio monitoring the coastal pollution, particularly near the petroleum terminals.For the evaluation of result quality concerning to the quality of those results, the work analysed the reference material certification NIST SRM 1566b Oyster Tissue. The precision of the results were also analysed using repetitions of mussel samples collected at the coastal of northern Sao Paulo state, Brazil. The NAA procedure consisted of 200 mg of sample and a synthetic standard of vanadium during a period of 8 s and under a thermal neutron flux of 6.6 x 1012 n cm-2 s-1 at the pneumatic station 4 of the IEA-R1 nuclear reactor of IPEN-CNEN/SP. After a 3 min decay, the measurements of the gamma activities of the sample and the standard were done using a Ge hyper pure semi-conductor detector, connected to gamma ray multichannel analyser. The vanadium were determined by the measurement of the gamma activity of the 52V through the 1434.08 keV peak, and half-life time of 3.75 min. The concentration of V were calculated by the comparative method. The obtained results indicated the viability of the NAA procedure established for the determination of vanadium in mussels

  5. Neutron Activation Analysis of Vanadium, Copper, Zinc, Bromine and Iodine in Pyura Microcosmus

    Most of the tunicates seem to accumulate vanadium more energetically than other marine organisms. However, there is a very great variation within the group. Maximum amounts of vanadium were found in the Ascididae family whereas in some species of the Pyuridae family vanadium was apparently absent. This paper describes the simple and rapid determination by activation analysis of vanadium, copper, zinc, bromine and iodine in Pyura microcosmus, a species of the Pyuridae family. The same elements were also investigated in the environmental sea-water. Samples of P. microcosmus and sea-water were collected from a point about 15 m below the surface in the Saronic Gulf near Athens. All irradiations of samples and standards were carried out with the DEMOCRITUS Reactor of the Nuclear Research Centre of Greece, at a neutron flux of 2 x 1011 n/cm2s. The time of irradiation with the pneumatic transfer system ranged from 1 to 25 min, depending on the element being determined. After irradiation and addition of inactive carriers, the radioisotopes of interest were isolated by fast radiochemical procedures based on solvent extraction techniques. Vanadium and copper were extracted as cupferrates into chloroform, and zinc was extracted with 8% methyldioctylamine into trichloroethylene. Bromine and iodine were distilled first and then separated from each other by selective redox and extraction procedures. The photopeak areas of 52V, 64Cu, 69mZn, 82Br and 128I were measured by means of a multichannel analyser and compared with those of standards of the above radionuclides processed in the same manner. After irradiation the time to complete the analysis ranged from 5 to 35 min depending on the element being determined. The quantities of the elements determined in P. microcosmus, expressed in micrograms per gram of dry matter, were: vanadium 1.0, copper 7.5, iodine 14.1, bromine 406 and zinc 702. The per cent concentration of the same elements found in the sea-water was as follows

  6. Thermodynamic calculation of carbonitrides solubility in low-carhon steels alloyed with vanadium and aluminium

    The aim of the study is to calculate the vanadium carbonitride solubility in low-carbon steels on the basis of data on VC and VN solubility, to describe phase equilibrium in the system with regard to all phases the formation of which is possible in an austenitic region, to perform the thermodynamic calculation and to carry out an experimental investigation with the purpose of checking the permissibility of accepted simplifications. It is shown that the #betta#-Fe-V(C,N)-AlN-Al2O3 system perfectly corresponds to the case of austenitic region in low-carbon steels with vanadium and aluminium. The equations which permit to calculate phase equilibrium in this system are derived. Thermodynamic calculations are performed and comparison of their results with the data of experimental investigation of phase composition is carried out. A perfect coinsidence of calculation and experiment results is shown

  7. Determination of vanadium in stainless steel and Ni-base alloys by NBPHA spectrophotometric method combined with chloroform extraction separation in media of sulfuric-hydrofluoric acid

    A new method of rapid vanadium analysis was proposed. In this method, vanadium is directly extracted and determined from sample solutions in sulfuric-hydrofluoric acid. The interference of the coexisting elements can be ignored in this method. Take one gram of sample into a 200 ml beaker, and add 30 ml of aqua regia. Then heat and dissolve it, and add 14 ml of sulfuric acid (1+1) and 5 ml of phosphoric acid. After cooling, dissolve the salts with a small amount of water. Thereafter, transfer it with use of water into a polyethylene separatory funnel, add 10 ml of 46% hydrofluoric acid, and dilute to 50 ml. Then, add 4 ml iron (II) ammonium sulfate solution (10%) and mix it thoroughly. Allow to stand for two or three minutes, add 10 ml of 45% ammonium persulfate solution and mix it thoroughly again. Allow to stand for about five minutes. Then, add exactly 20 ml of BPHA-chloroform solution (0.1%) and shake and mix it vigorously for two minutes. After a while, transfer the chloroform complex into a 10 mm cell through a piece of absorbent cotton. Then, determine vanadium by measuring the absorbance at the wave length of 530 nm against a chloroform reference. This method can be applicable to the analysis of vanadium in other metals and alloys than stainless steel and Ni-base alloys. (Iwakiri, K.)

  8. The effect of nitrogen on the coarsening rate of precipitate phases in iron-based alloys with chromium and vanadium. Experimental and theoretical investigations

    Lindwall, Greta; Frisk, Karin [Swerea KIMAB AB, Kista (Sweden). Virtual Lab.

    2013-05-15

    A comparison of the coarsening of nitrogen-rich vanadium precipitates and the coarsening of carbon-rich vanadium precipitates is presented. The precipitate phases are studied experimentally, via fabrication of model alloys, and theoretically, via simulations utilizing the DICTRA software. The experimental investigations indicate that the nitrogen-rich precipitates exhibit a slower coarsening behaviour than the carbon-rich precipitates. Analysis using thermodynamic and kinetic modelling shows that this can be explained by the higher thermodynamic stability of the nitrogen-rich precipitate compared to the carbon-rich precipitate. The calculated coarsening rates are compared with the measured rates, and found to be in satisfactory agreement using reasonable values for the interfacial energies. The investigations are motivated by the fine precipitate size distribution of nitrides and carbonitrides characteristic for high nitrogen alloyed tool steels produced by means of powder metallurgy. (orig.)

  9. Grain boundary chemistry and heat treatment effects on the ductile-to-brittle transition behavior of vanadium alloys

    The ductile-to-brittle transition (DBTT) behavior of vanadium alloys currently being developed for fusion power systems is sensitive to thermo-mechanical processing variables and history. Factors which contribute to this sensitivity are (1) pickup of interstitial impurities such as oxygen, nitrogen and carbon during heat treatments and elevated temperature forming operations, (2) the final grain size achieved, (3) removal of impurities from solid solution due to precipitation reactions, and (4) segregation of impurities to grain boundaries. Previous work on a V-5Cr-5Ti (Heat No. 832394) alloy suggested that sulfur segregation or precipitation during final mill annealing may play a role in determining DBTT behavior. The effect of heat treatment on grain boundary chemistry and Charpy impact behavior was investigated using a production-scale heat of V-4Cr-4Ti (Heat No. 832665). Specimens were examined with Auger electron spectroscopy to characterize grain boundary microchemistry for correlation with Charpy impact test results obtained from one-third size specimens. (orig.)

  10. Enhanced erythropoietin and suppression of γ-glutamyl trans-peptidase (GGT) activity in murine lymphoma following administration of vanadium

    Administration of vanadium as ammonium mono-vanadate (0.005 μg/0.1 ml/mouse/day) was found to reduce the tumor cell proliferation in the host mice bearing Dalton's lymphoma. The high activity of γ-glutamyl trans-peptidase (CCT), a neoplastic marker, was seen in the host cells bearing lymphoma. Vanadium effectively prevented an increase in activity of γ-glutamyl trans-peptidase and maintained a sustained low activity of this enzyme. In addition, an improvement of the hematological aspects of the mice and almost fourfold elevation of erythropoietin (Epo) was obtained following vanadium treatment. This in Epo activity may play a vital role in regulating the growth of cellular neoplasia. The present study further confirms the anti-tumorigenic potential of vanadium in the control of tumor progression in lymphoma via modulating several factors involving erythropoiesis and may emerge as a new chemo-preventive agent for the future. (author)

  11. Relationship of microstructure and tensile properties for neutron-irradiated vanadium alloys

    The microstructures in V-15Cr-5Ti, V-10Cr-5RTi, V-3Ti-1Si, V-15Ti-7.5Cr, and V-20Ti alloys were examined by transmission electron microscopy after neutron irradiation at 600 degree C to 21--84 atom displacements per atom in the Materials Open Test Assembly of the Fast Flux Test Facility. The microstructures in these irradiated alloys were analyzed to determine the radiation-produced dislocation density, precipitate number density and size, and void number density and size. The results of these analyses were used to compute increases in yield stress and swelling of the irradiated alloys. The computed increase in yield stress was compared with the increase in yield stress determined from tensile tests on these irradiated alloys. This comparison made it possible to evaluate the influence of alloy composition on the evolution of radiation-damaged microstructures and the resulting tensile properties. 11 refs

  12. Quality assurance of neutron activation analysis of traces of vanadium in workplace air, the environment and human tissues

    The essentiality, distribution and toxicology of vanadium are still areas of ongoing research at the present time. Analytical quality assurance procedures, such as analysis of suitable reference materials (RMs) or comparative analyses using independent analytical techniques, should be extensively applied in these studies in order to elucidate the existing discrepancies and gaps in our knowledge of vanadium levels in the biosphere, environment and especially in human tissues, where vanadium is present at extremely low levels. Results of vanadium determination by instrumental and radiochemical neutron activation analysis at concentrations ranging from less than 0.001 mg/kg to several hundreds of mg/kg in a number of environmental and biological RMs, mostly those recently prepared, are presented. Problems of quality assurance in vanadium related environmental studies are discussed in terms of the availability of suitable matrix and vanadium level matched RMs for the following matrices: workplace and ambient air; soils, sediments and waters; botanical materials; and animal and human tissues. The possibilities of pursuing quality assurance by comparative analyses of the above matrices using independent analytical techniques are briefly evaluated. The need for quality assurance of the pre-analytical stages of the above studies, especially those aimed at establishing normal vanadium values in selected human tissues, is also mentioned. (author)

  13. 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

    Jakobsen, Stig Storgaard; Larsen, Agnete; Stoltenberg, Meredin;

    2007-01-01

    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...... 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...

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

    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, 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

  15. Vanadium alloy membranes for high hydrogen permeability and suppressed hydrogen embrittlement

    The structural properties and hydrogen permeation characteristics of ternary vanadium–iron–aluminum (V–Fe–Al) alloy were investigated. To achieve not only high hydrogen permeability but also strong resistance to hydrogen embrittlement, the alloy composition was modulated to show high hydrogen diffusivity but reduced hydrogen solubility. We demonstrated that matching the lattice constant to the value of pure V by co-alloying lattice-contracting and lattice-expanding elements was quite effective in maintaining high hydrogen diffusivity of pure V

  16. ETHYLENE/1-HEXENE COPOLYMERIZATION BY SALICYLALDIMINATO VANADIUM(Ⅲ) COMPLEXES ACTIVATED WITH DIETHYLALUMINUM CHLORIDE

    Ji-qian Wu; Yan-guo Li; Bai-xiang Li; Yue-sheng Li

    2011-01-01

    Mono salicylaldirninato vanadium(Ⅲ) complexes (1a-1f) [RN =CH(ArO)]VCl2(THF)2 (Ar =C6H4 (1a-1e),R =Ph,1a; R =p-CF3Ph,1b; R =2,6-Me2Ph,1c; R =2,6-iPr2Ph,1d; R =cyclohexyl,1e; Ar =C6H2tBu2(2,4),R =2,6-iPr2Plh,1f) and bis(salicylaldiminato) vanadium(Ⅲ) complexes (2a-2f) [RN =CH(ArO)]2VCl(THF)x (Ar =C6H4 (2a-2e),x =1(2a-2e),R =Ph,2a; R =p-CF3Ph,2b; R =2,6-Me2Ph,2c; R =2,6-iPr2Ph,2d; R =cyclohexyl,2e; Ar =C6H2tBu2(2,4),R =2,6-iPr2Ph,x =0,2f) have been evaluated as the active catalysts for ethylene/1-hexene copolymerization in the presence of Et2AlCl.The ligand substitution pattern and the catalyst structure model significantly influenced the polymerization behaviors such as the catalytic activity,the molecular weight and molecular weight distribution of the copolymers etc.The highest catalytic activity of 8.82 kg PE/(mmolv·h) was observed for vanadium catalyst 2d with two 2,6-diisopropylphenyl substituted salicylaldiminato ligands.The copolymer with the highest molecular weight was obtained by using mono salicylaldiminato vanadium catalyst 1f having ligands with tert-butyl at the ortho andpara of the aryloxy moiety.

  17. Thermal oxidation of vanadium-free Ti alloys: An X-ray photoelectron spectroscopy study

    Lopez, Maria Francisca, E-mail: mflopez@icmm.csic.es [Department of Surfaces and Coatings, ICMM-CSIC, Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain); Gutierrez, Alejandro [Departamento de Fisica Aplicada and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Jimenez, Jose Antonio [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo 8, E-28040 Madrid (Spain); Martinesi, Maria; Stio, Maria; Treves, Cristina [Department of Biochemical Sciences of University of Florence, Viale Morgagni 50, 50134 Florence (Italy)

    2010-04-06

    In the present work, X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of three alloys for biomedical applications: Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb. The surface of these alloys was modified by annealing in air at 750 deg. C for different times with the aim of developing an oxide thick layer on top. The evolution of surface composition with annealing time was studied by XPS, and compared with the composition of the native oxide layer present on the samples before annealing. Two different oxidation trends were observed depending on the alloying elements and their corresponding diffusion kinetics, which give rise to different chemical species at the topmost layers. These results were linked with an evaluation of the biological response of the alloys by bringing them in contact with human peripheral blood mononuclear cells (PBMC).

  18. Thermal oxidation of vanadium-free Ti alloys: An X-ray photoelectron spectroscopy study

    In the present work, X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of three alloys for biomedical applications: Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb. The surface of these alloys was modified by annealing in air at 750 deg. C for different times with the aim of developing an oxide thick layer on top. The evolution of surface composition with annealing time was studied by XPS, and compared with the composition of the native oxide layer present on the samples before annealing. Two different oxidation trends were observed depending on the alloying elements and their corresponding diffusion kinetics, which give rise to different chemical species at the topmost layers. These results were linked with an evaluation of the biological response of the alloys by bringing them in contact with human peripheral blood mononuclear cells (PBMC).

  19. Transmission measurements of guides for ultra-cold neutrons using UCN capture activation analysis of vanadium

    Frei, A., E-mail: Andreas.Frei@ph.tum.d [Technische Universitaet Muenchen, Physik Department, 85748 Garching (Germany); Schreckenbach, K.; Franke, B.; Hartmann, F.J.; Huber, T.; Picker, R.; Paul, S. [Technische Universitaet Muenchen, Physik Department, 85748 Garching (Germany); Geltenbort, P. [Institut Laue-Langevin, 38042 Grenoble (France)

    2010-01-01

    The efficient transport of ultra-cold neutrons (UCN) from their source to the experimental site is a major issue for various kinds of precision experiments. Neutron guides often have to transport the UCN several tens of meters with acceptable losses. In order to qualify the guides, their UCN transmission properties have to be determined with high precision. For this purpose we have developed a novel method. The transmitted UCN were absorbed at the end of the guide in a vanadium disc producing the {beta}-emitter {sup 52} V (half life 3.74 min). The intensity of the 1434 keV {gamma}-ray following the {beta}-decay was measured. UCN guides of non-magnetic nickel alloys made by the replication technique were studied. They show a high Fermi pseudopotential V{sub F} for UCN and a low surface roughness. For these guides the transmission per meter was determined with a relative error of +-0.6%, resulting in values above 0.95/m. By an absolute calibration of the gamma-ray detection system we also deduced the absolute value of the UCN current absorbed in the vanadium plate. Possible applications of this method are discussed.

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

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

    1997-08-01

    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 Program (RDP), has been completed by Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). CVN impact tests on sheet material indicate that the material has properties comparable to other previously-processed V-4Cr-4Ti and V-5Cr-5Ti alloys. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RDP, and research into several joining methods for fabrication of the RDP components, including resistance seam, friction, and electron beam welding, and explosive bonding is being pursued. Preliminary trials have been successful in the joining of V-alloy to itself by resistance, friction, and electron beam welding processes, and to Inconel 625 by friction welding. In addition, an effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625, in both tube-to-bar and sheet-to-sheet configurations, has been initiated, and results have been encouraging.

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

    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 Program (RDP), has been completed by Wah Chang (formerly Teledyne Wah Chang) of Albany, Oregon (WCA). CVN impact tests on sheet material indicate that the material has properties comparable to other previously-processed V-4Cr-4Ti and V-5Cr-5Ti alloys. Joining of V-4Cr-4Ti alloy has been identified as the most critical fabrication issue for its use in the RDP, and research into several joining methods for fabrication of the RDP components, including resistance seam, friction, and electron beam welding, and explosive bonding is being pursued. Preliminary trials have been successful in the joining of V-alloy to itself by resistance, friction, and electron beam welding processes, and to Inconel 625 by friction welding. In addition, an effort to investigate the explosive bonding of V-4Cr-4Ti alloy to Inconel 625, in both tube-to-bar and sheet-to-sheet configurations, has been initiated, and results have been encouraging

  2. Effect of replacement of vanadium by iron on the electrochemical behaviour of titanium alloys in simulated physiological media

    Mareci, D.

    2009-02-01

    Full Text Available The electrochemical behaviour of Ti6Al4V, Ti6Al3.5Fe and Ti5Al2.5Fe alloys has been evaluated in Ringer’s solution at 25 °C. The effect of the substitution of vanadium in Ti6Al4V alloy has been specifically addressed. The evaluation of the corrosion resistance was carried out through the analysis of the open circuit potential variation with time, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS tests. Very low current densities were obtained (order of nA/cm2 from the polarization curves and EIS, indicating a typical passive behaviour for all investigated alloys. The EIS results exhibited relative capacitive behaviour (large corrosion resistance with phase angle close to –80° and relative high impedance values (order of 105 Ω•cm2 at low and medium frequencies, which are indicative of the formation of a highly stable film on these alloys in Ringer’s solution. In conclusion, the electrochemical behaviour of Ti6Al4V is not affected by the substitution of vanadium with iron.

    El comportamiento electroquímico de las aleaciones Ti6Al4V, Ti6Al3.5Fe y Ti5Al2.5Fe fue evaluado en una disolución Ringer a 25 °C. Se ha estudiado especialmente el efecto de la sustitución del vanadio en la aleación Ti6Al4V. La evaluación de la resistencia a la corrosión se ha llevado a cabo a través del análisis de la variación del potencial de un circuito abierto con el tiempo, las curvas de polarización potenciodinámicas y los ensayos de espectroscopía de impedancia electroquímica (EIS. Se han obtenido densidades de corriente muy bajas (del orden de nA/cm2 en las curvas de polarización y EIS, indicando un comportamiento pasivo típico para todas las aleaciones investigadas. Los resultados de la EIS mostraron un comportamiento capacitivo relativo (gran resistencia a la corrosión con ángulos de fase próximos a –80° y valores de impedancia relativamente altos (del orden de

  3. Experimental investigation and thermodynamic modeling of molybdenum and vanadium-containing carbide hardened iron-based alloys

    Highlights: ► Improvement of a carbide selective extraction method. ► Determination of experimental data on the Fe–C–Cr–Mo–V system for carbides above 900 °C: crystallographic structures and compositions of precipitates, matrix composition. ► High molybdenum solubility in FCC carbides. ► Improvement of thermodynamic databases from experimental results. ► Validation of the optimized database with different compositions steels. -- Abstract: A technique for the microstructural study of steels, based on the use of matrix dissolution to collect the very low number density precipitates formed in martensitic steels, has been considerably improved. This technique was applied to two different grades of alloy, characterized by high nickel and cobalt contents and varying chromium, molybdenum and vanadium contents. The technique was implemented at temperatures ranging between 900 °C and 1000 °C, in order to accurately determine experimental data including the crystallographic structure and chemical composition of the carbides, the carbide solvus temperatures, and variations in the chemical composition of the matrix. These experimental investigations reveal that the solubility of molybdenum in FCC carbides can be very high. These results have been compared with the behavior predicted by computational thermodynamics, and used to evaluate and improve the thermodynamic Matcalc steel database. This upgraded database has been validated on three other steels with different chemical compositions, characterized by the same Fe–Cr–Mo–V–C system

  4. Pseudogap state and strong scattering of current carriers by local spin moments as the mechanisms of appearance of semiconductor properties of almost stoichiometrical iron-vanadium-aluminium alloys

    New experimental data are obtained which substantiate the physical nature of semiconductor properties of Fe2-xV1+x Al alloys with almost stoichiometrical composition (x = 0). We investigated low temperature thermoelectric power of two alloys of characteristic compositions: one alloy, enriched with vanadium, exhibited a pseudogap in the density of states of electrons with Fermi energy and the other one vanadium depleted, more strong influence of the scattering of electrons by localized spins is revealed. The experimental temperature dependences of thermoelectric power at low temperatures displayed characteristic anomalies that were observed for the first time and which in line with our analysis conform to the manifestations the effects above. Using the existing theories, the anomalous contributions of the both effects (types) were interpreted, the parameters, characterizing them have determined and the specific features of their presence in V-depleted and V-enriched alloys have also established. The data for thermoelectric power in magnetic field were obtained. It is found that thermoelectric power decreases considerably with increasing field intensity, confirming the key role of the mechanism of current carrier scattering by localized moments.

  5. Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

    Gubbi, A.N.; Rowcliffe, A.F.; Lee, E.H.; King, J.F.; Goodwin, G.M. [Oak Ridge National Lab., TN (United States)

    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) 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.

  6. Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

    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) 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

  7. Measuring and modeling oxygen diffusion in niobium-vanadium and niobium-palladium alloys

    Hennessey, Theresa P.

    Niobium alloys are under consideration for high-temperature aerospace applications, but they have poor oxidation resistance and need high-temperature coatings for protection in severe environments. Our approach to creating an oxidation-resistant Nb alloy is to identify substitutional solute elements that lower the diffusivity of oxygen in Nb. In theory, this will induce a transition from internal to external oxidation and promote the formation of a desirable, protective oxide scale. The objective of this particular project is to compare the oxygen diffusivity in Nb alloys that contain either trap or repulsive sites. In Nb, oxygen atoms diffuse via an interstitial mechanism, and they can interact with substitutional solute atoms in different ways. The interstitial sites adjacent to a substitutional atom constitute a "zone of influence". If the sites in this zone have a lower energy than the normal sites, they are called "trap" sites. If these sites have a higher energy, they are called "repulsive" sites. Oxygen diffusion is inhibited in both cases: trap sites hold the oxygen and keep it from diffusing further, while repulsive sites block the path of the oxygen. Two new mathematical models for interstitial diffusion in these systems were derived from probability and statistical thermodynamic theory. The models were verified using a new random-walk computer simulation of oxygen diffusion through Nb alloys. These models were also tested experimentally by measuring oxygen diffusivity in Nb-V and Nb-Pd alloys. These results showed that V atoms create trap sites for oxygen atoms, confirming previous work. However, there was not enough data to prove definitively that Pd atoms create repulsive sites, as expected by theory.

  8. Development of electrically insulating coatings on vanadium alloys for lithium-cooled blankets

    The self-cooled lithium blanket concept with a vanadium structure offers a potential for high performance with attractive safety and environmental features. Based on blanket design studies, it became apparent that electrically insulating duct walls would be required to reduce the magnetohydrodynamic (MHD) pressure drop for liquid metal-cooled blankets for high magnetic field fusion devices. As a result, development of insulator coatings was recommended as the most appropriate approach for resolving this issue. Oxides such as CaO, Y2O3, BeO, MgO, MgAl2O4, and Y3Al2O12 and nitrides such as AlN, BN and Si3N2 were initially considered potential candidate coating materials. Based on results of scoping studies, CaO and AlN have been selected as primary candidates for further development. Progress on the development of CaO and AlN coatings, including in-situ formation and electrical properties measurements, are summarized in this paper

  9. Density decrease in vanadium-base alloys irradiated in the dynamic helium charging experiment

    Chung, H.M.; Galvin, T.M.; Smith, D.L. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    Combined effects of dynamically charged helium and neutron damage on density decrease (swelling) of V-4Cr-4Ti, V-5Ti, V-3Ti-1Si, and V-8Cr-6Ti alloys have been determined after irradiation to 18-31 dpa at 425-600{degrees}C in the Dynamic helium Charging Experiment (DHCE). To ensure better accuracy in density measurement, broken pieces of tensile specimens {approx} 10 times heavier than a transmission electron microscopy (TEM) disk were used. Density increases of the four alloys irradiated in the DHCE were <0.5%. This small change seems to be consistent with the negligible number density of microcavities characterized by TEM. Most of the dynamically produced helium atoms seem to have been trapped in the grain matrix without significant cavity nucleation or growth.

  10. Study of in-reactor creep of vanadium alloy in the HFIR RB-12J experiment

    Strain, R.V.; Konicek, C.F.; Tsai, H. [Argonne National Lab., IL (United States)

    1996-10-01

    Biaxial creep specimens will be included in the HFIR RB-12J experiment to study in-reactor creep of the V-4Cr-4Ti alloy at {approx}500{degrees}C and 5 dpa. These specimens were fabricated with the 500-kg, heat (832665) material and pressurized to attain 0, 50, 100, 150, and 200 MPa mid-wall hoop stresses during the irradiation.

  11. Quadrupole interactions in molybdenum base dilute binary vanadium and niobium alloys

    The 95Mo resonance in pure Mo after filing and annealing near 10000C consists entirely of the m = 1/2 → -1/2 transition. Decreased absorption intensity and line broadening caused by solute addition can be understood as a direct result of second order perturbation of the m = 1/2 → -1/2 transition. A/h for 95Mo is roughly 200 Hz for nuclei near either V or Nb in Mo. The data establish the magnitude and the mechanism of the broadening observed in 95Mo when V and Nb are present as minor alloying elements

  12. Effects of vanadium on the microstructure and mechanical properties of a high strength low alloy martensite steel

    Highlights: • Precipitation behavior of (Ti, V)C precipitates was elucidated. • (Ti, V)C precipitation can induce the grain refinement after reheating-quenching process. • Ultra-fine austenite grains with the average size smaller than 5 μm were obtained. • The microstructure transformed from ultra-fine austenite was analyzed. • Excellent mechanical properties were achieved in ultra-fine grained steel. - Abstract: The precipitation behavior of vanadium-rich carbides formed during the reheating processes and its influence on the microstructure and mechanical properties have been systematically investigated in a high strength low alloy martensite steel. It was found that the nano-sized (Ti, V)C particles mainly precipitated during reheating rather than soaking at the austenitization process. For their pinning effect on grain growth, ultra-fine austenite grain with the average size of 3.5 μm formed during holding at 880 °C for 1 h. As the austenitization temperature increased, the prior nano-sized (Ti, V)C coarsened and its volume fraction decreased, which led to increment of austenite grain size. Excellent combined mechanical properties such as tensile strength 1670 MPa, yield strength 1460 MPa, elongation 10% at room temperature and impact energy (Akv) 57 J at −40 °C were obtained in the ultra-fine grained steels. In particular, the low-temperature toughness was improved by grain refinement. The strengthening mechanisms were also investigated by comparing the experimental results with theoretical calculation. The variation of yield strength with the condition of heat treatment was discussed in detail

  13. Results of R and D for lithium/vanadium breeding blanket design

    The self-cooled lithium/vanadium blanket concept has several attractive features for fusion power systems, including reduced activation, resistance to radiation damage, accommodation of high heat loads and operating to temperatures of 650--700 C. The primary issue associated with the lithium/vanadium concept is the potentially high MHD pressure drop experienced by the lithium as it flows through the high magnetic field of the tokamak. The solution to this issue is to apply a thin insulating coating to the inside of the vanadium alloy to prevent the generation of eddy currents within the structure that are responsible for the high MHD forces and pressure drop. This paper presents progress in the development of an insulator coating that is capable of operating in the severe fusion environment, progress in the fabrication development of vanadium alloys, and a summary of MHD testing. A large number of small scale tests of vanadium alloy specimens coated with CaO and AlN have been conducted in liquid lithium to determine the resistivity and stability of the coating. In-situ measurements in lithium have determined that CaO coatings, ∼ 5 microm thick, have resistivity times thickness values exceeding 106 Ω-cm2. These results have been used to identify fabrication procedures for coating a large vanadium alloy (V-4Cr-4Ti) test section that was tested in the ALEX (Argonne Liquid metal Experiment) facility. Similar test sections have been produced in both Russia and the US

  14. DNA-Binding and Topoisomerase-I-Suppressing Activities of Novel Vanadium Compound Van-7

    Xiao-mei Mo

    2012-01-01

    Full Text Available Vanadium compounds were studied during recent years to be considered as a representative of a new class of nonplatinum metal anticancer agents in combination to its low toxicity. Here, we found a vanadium compound Van-7 as an inhibitor of Topo I other than Topo II using topoisomerase-mediated supercoiled DNA relaxation assay. Agarose gel electrophoresis and comet assay showed that Van-7 treatment did not produce cleavable complexes like HCPT, thereby suggesting that Topo I inhibition occurred upstream of the relegation step. Further studies revealed that Van-7 inhibited Topo I DNA binding involved in its intercalating DNA. Van-7 did not affect the catalytic activity of DNase I even up to100 μM. Van-7 significantly suppressed the growth of cancer cell lines with IC50 at nanomolar concentrations and arrested cell cycle of A549 cells at G2/M phase. All these results indicate that Van-7 is a potential selective Topo I inhibitor with anticancer activities as a kind of Topo I suppressor, not Topo I poison.

  15. DNA-Binding and Topoisomerase-I-Suppressing Activities of Novel Vanadium Compound Van-7.

    Mo, Xiao-Mei; Chen, Zhan-Fang; Qi, Xin; Li, Yan-Tuan; Li, Jing

    2012-01-01

    Vanadium compounds were studied during recent years to be considered as a representative of a new class of nonplatinum metal anticancer agents in combination to its low toxicity. Here, we found a vanadium compound Van-7 as an inhibitor of Topo I other than Topo II using topoisomerase-mediated supercoiled DNA relaxation assay. Agarose gel electrophoresis and comet assay showed that Van-7 treatment did not produce cleavable complexes like HCPT, thereby suggesting that Topo I inhibition occurred upstream of the relegation step. Further studies revealed that Van-7 inhibited Topo I DNA binding involved in its intercalating DNA. Van-7 did not affect the catalytic activity of DNase I even up to100 μM. Van-7 significantly suppressed the growth of cancer cell lines with IC(50) at nanomolar concentrations and arrested cell cycle of A549 cells at G2/M phase. All these results indicate that Van-7 is a potential selective Topo I inhibitor with anticancer activities as a kind of Topo I suppressor, not Topo I poison. PMID:23055949

  16. Irradiation-induced precipitation and mechanical properties of vanadium alloys at <430 C

    Chung, H.M.; Gazda, J.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    Recent attention to V-base alloys has focused on the effect of low-temperature (<430 C) irradiation on tensile and impact properties of V-4Cr-4Ti. In previous studies, dislocation channeling, which causes flow localization and severe loss of work-hardening capability, has been attributed to dense, irradiation-induced precipitation of very fine particles. However, efforts to identify the precipitates were unsuccessful until now. In this study, analysis by transmission electron microscopy (TEM) was conducted on unalloyed V, V-5Ti, V-3Ti-1Si, and V-4Cr-4Ti specimens that were irradiated at <430 C in conventional and dynamic helium charging experiments. By means of dark-field imaging and selected-area-diffraction analysis, the characteristic precipitates were identified to be (V,Ti{sub 1{minus}x})(C,O,N). In V-3Ti-1Si, precipitation of (V,Ti{sub 1{minus}x})(C,O,N) was negligible at <430 C, and as a result, dislocation channeling did not occur and work-hardening capability was high.

  17. Microstructure of A γ-α2-β Ti-Al alloy containing iron and vanadium

    Ordered β-phase (B2 CsCl structure) has been identified in a Ti-45.5 at.% Al-1.6 at.% Fe-1.1 at.% V-0.7 at.% B alloy being developed for high temperature applications. Selected area electron diffraction has been used to identify the orientation relationships and interface planes of the β-phase with the bulk γ-TiAl and α2-Ti3Al phases. Energy dispersive X-ray spectroscopy indicates that the β-phase has approximately the same Ti/Al ratio as the α2-Ti3Al phase, and is stabilized within the microstructure by Fe and V. Channeling enhanced microanalysis studies (ALCHEMI) show that the Fe and V both occupy the same sublattice as the Al atoms in the cubic β-phase structure, and that Fe occupies the Al sites in the γ-phase. Fe and V are concentrated in the β-phase, which effectively getters these dopants from the γ and α2 phases. Titanium ferride precipitates, probably FeTi, have been observed within the β-phase

  18. Influence of Ni doping on anti-poison properties of vanadium

    The VNi0.01 alloy was fabricated by induction melting. The VNi0.01 alloy and pure vanadium were poisoned by 0.5% CO2 in deuterium (1.0 MPa) after activation. The deuterium absorption rate of VNi0.01 alloy was faster than that of pure vanadium in the early stage, though it rapidly decreased to zero. After removing the gas by heating and vacuumizing, the pure deuterium was resent to sample chamber with final pressure at 1.0 MPa. The ability of deuterium absorption of VNi0.01 alloy was regenerated as it was fully activated, but the absorption rate of pure vanadium was lower than it was first activated. Besides, the pressure boost property of VNi0.01 alloy was superior to pure vanadium in the temperature range of 300-400 K. It is expected that VNi0.01 alloy could be used in pressure boost chemical bed. The results of these studies will provide a direct basis for application of the material. (authors)

  19. High performance electrodes in vanadium redox flow batteries through oxygen-enriched thermal activation

    Pezeshki, Alan M.; Clement, Jason T.; Veith, Gabriel M.; Zawodzinski, Thomas A.; Mench, Matthew M.

    2015-10-01

    The roundtrip electrochemical energy efficiency is improved from 63% to 76% at a current density of 200 mA cm-2 in an all-vanadium redox flow battery (VRFB) by utilizing modified carbon paper electrodes in the high-performance no-gap design. Heat treatment of the carbon paper electrodes in a 42% oxygen/58% nitrogen atmosphere increases the electrochemically wetted surface area from 0.24 to 51.22 m2 g-1, resulting in a 100-140 mV decrease in activation overpotential at operationally relevant current densities. An enriched oxygen environment decreases the amount of treatment time required to achieve high surface area. The increased efficiency and greater depth of discharge doubles the total usable energy stored in a fixed amount of electrolyte during operation at 200 mA cm-2.

  20. Model of Calculating Activity of Nitrogen and Vanadium in Fe-C-V-N Molten Metal

    PENG Jun; WANG Shi-jun; DONG Yuan-chi; LIU Li-xia; ZHOU Yun; CHEN Er-bao

    2008-01-01

    The solubility of nitrogen in the Fe-C-V-N system was measured at 1 708 K and the model of calculating activity (action concentration) of nitroge.n (N) and vanadium (V) was derived according to the phase diagram and the coexistence theory of the metal melt structure.The solubility expression of nitrogen in the Fe-C-V-N system at 1 708 K was wN=0.058 194-0.010 367WC+0.005 543 4wV.Comparing the computing results with the experimental results,a satisfactory conclusion could be obtained.The analysis of the Fe-C-V-N system using this model showed that VN was present in a high temperature metal melt,which would reduce the action concentration of nitrogen obviously.It was consequently disadvantageous to the removal of nitrogen from hot metal.

  1. 熔融钒渣直接氧化钠化提钒新工艺研究%A New Process for Vanadium Extraction from Molten Vanadium Slag by Direct Oxidation and Sodium Activating Method

    宋文臣; 李宏

    2012-01-01

    To address the problem of heat waste of vanadium slag in the existing vanadium extraction process, a new process is proposed in this paper to extract vanadium from molten vanadium slag by direct oxidation and sodium activating method. On the basis of current vanadium extraction process, the new process was verified by thermodynamic and kinetic calculation and analysis, and then simulation tests were carried out in the laboratory. The results show that with enough heat, vanadium slag can be kept in molten state during the vanadium extraction process. The dynamic conditions of the new process are noticeably better than the existing process. The oxidization rate of vanadium slag is about 90% and vanadium leaching rate can reach 82% or above with enough oxygen and Na2CO3 content at 20% ~ 30% of vanadium slag' weight. Thus, the feasibility of the new process is confirmed by the results.%针对现行钒渣焙烧工艺中存在的钒渣高温物理热的浪费问题,提出“熔融钒渣直接氧化钠化提钒”新工艺.在现行工艺基础上,对新工艺进行了热力学和动力学的计算与分析,最后进行了新工艺的实验室模拟试验.研究结果表明:新工艺条件下,钒渣在反应过程中热量充足会保持良好的熔融状态;新工艺的动力学条件明显优越于现行工艺;实验室试验结果验证了新工艺的可行性,在供氧充足,Na2CO3用量为20%~30%的条件下,钒渣氧化率约为90%,钒浸出率在82%以上.

  2. Individual simultaneous first derivative spectrophotometric determination of copper and vanadium in alloy steels and complex materials with 2-hydroxy-1-naphthaldehydebenzoylhydrazone

    2-Hydroxy-l-naphthaldehydebenzoylhydrazone (OHNABH) reacts with VV and CuII at pH 5.0 forming respectively yellow and green coloured soluble complexes in 30% DMF. The first derivative amplitude measurements show that Beer's law is obeyed in the range 0-7.5μg ml-1 for V at 465 nm and 0-4.5 μg ml-1 for Cu at 443 nm. The sensitivity of the method is greater than the zero order method, and foreign ions like UVI, ThIV, CrVI which interfere in zero order method, do not interfere even in large excess. Vanadium and copper present in a mixture are simultaneous determined without solving the simultaneous equations by measuring the first derivative amplitudes at 412.6 and 430.2 nm for V and Cu, respectively. The method is applied for the determination of Cu in food materials, V in alloy steels, and both V and Cu in chromium-vanadium steel. (author)

  3. 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

    S S Jakobsen

    2007-09-01

    Full Text Available 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.

  4. The Recovery and Recrystallization of the Cold Rolled V-W-Ti Alloys

    CHENJiming; T.Muroga; T.Nagasaka1; XUYing; XUZengyu

    2002-01-01

    Vanadium alloys, especially that of V4Cr4Ti, are supposed as the promising candidate structural material for fusion applications for their good thermal properties, high temperature strength and the inherent low activation characteristics. However, in recent

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

    Tsai, H.; Gazda, J.; Nowicki, L.J.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    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 produced no notable differences.

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

    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).

  7. Vanadium nanobelts coated nickel foam 3D bifunctional electrode with excellent catalytic activity and stability for water electrolysis

    Yu, Yu; Li, Pei; Wang, Xiaofang; Gao, Wenyu; Shen, Zongxu; Zhu, Yanan; Yang, Shuliang; Song, Weiguo; Ding, Kejian

    2016-05-01

    Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity.Pursuit of highly active, stable and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key point for large-scale water splitting. A vanadium nanobelts coating on a nickel foam (V/NF) is proposed as an excellent 3D bifunctional electrode for water electrolysis here, which exhibits high activities with overpotentials of 292 and 176 mV at 10 mA cm-2 for OER and HER, respectively. When employed as a bifunctional electrocatalyst in an alkaline water electrolyzer, a cell voltage of 1.80 V was required to achieve 20 mA cm-2 with a slight increase during a 24 h durability test. The existence of the appropriate amount of nitrogen and oxygen elements in the surface region of vanadium nanobelts is regarded to be responsible for the electrocatalytic activity. Electronic supplementary information (ESI) available: More SEM, TEM images, XRD patterns, LSV curves, XPS spectra. See DOI: 10.1039/c6nr02395a

  8. PL and EL properties of Tm-activated vanadium oxide-based phosphor thin films

    The preparation of high-luminance blue emitting Tm-activated multicomponent oxide phosphor thin films is described. The phosphor thin films were deposited on thick BaTiO3 ceramic sheets by r.f. magnetron sputtering using powder targets. A very high photoluminescence (PL) intensity in blue emission could be observed in postannealed Tm-activated gadolinium oxide-vanadium oxide Gd0.5-V0.5-O:Tm thin films prepared using Tm2O3-doped (Gd2O3)0.5-(V2O5)0.5 targets (V2O5 content of 50 mol.%). It should be noted that thin films of this phosphor postannealed at 1100 deg. C in air exhibited higher PL intensity than those from commercially available blue BaMgAl14O23:Eu (BAM) phosphor powder and Gd0.5-V0.5-O:Tm powders. In addition, a Gd0.5-V0.5-O:Tm thin-film electroluminescent device exhibited a blue emission that was the same as the PL emission

  9. Activity Enhancement of Vanadium Catalysts with Ultrasonic Preparation Process for the Oxidation of Sulfur Dioxide

    Zhenxing Chen; Honggui Li; Lingsen Wang

    2003-01-01

    The effect of ultrasonic cavitations on the activity of vanadium catalysts at low temperatures for the oxidation of sulfur dioxide, in which refined carbonized mother liquor had been added, was investigated.Twenty minutes were needed to produce obvious cavitations when the catalyst raw material was treated in the 50 W ultrasonic generator. However, only 10 minutes would be needed in a 150 W ultrasonic generator.The higher the temperature of the wet material, the less time was needed to produce cavitations, and the optimal temperature was 60 ℃. The water content in the wet material mainly affected the quantity of cavitations. Ls-8 catalyst was prepared using ultrasonic. Its activity for conversion of SO2 reached to 52.5% at 410 ℃ and 4.2% at 350 ℃. The differential thermal analyses indicate that both endothermic peaks and exothermic peaks noticeably shifted forward compared with Ls catalyst prepared without ultrasonic, and SEM results show a uniform pore size distribution for Ls-8 catalyst.

  10. Complex steel saturation with niobium and vanadium

    Studies on determining possibility of niobium and vanadium alloying with carbides were conducted. Possibility of simultaneous saturation of carbon steels with niobium and vanadium was established. Diffusion layers coated on surfaces of 45, U8A and U10A steels under different conditions. It is shown that increase of coating density by means of alloying favours the increase of its corrosion resistance in water and aqueous solutions of salt and soda 2 times, wear resistance -1.6-5 times

  11. Strategies for enhancing electrochemical activity of carbon-based electrodes for all-vanadium redox flow batteries

    Highlights: ► Improved reactions at the positive electrode in all-vanadium redox flow batteries. ► Graphene-derived and PAN-modified electrodes have been successfully prepared. ► Modification with bimetallic CuPt3 nanocubes yielded the best catalytic behavior. ► N and O-containing groups enhances the vanadium flow battery performance. - Abstract: Two strategies for improving the electroactivity towards VO2+/VO2+ redox pair, the limiting process in all-vanadium redox flow batteries (VFBs), were presented. CuPt3 nanoparticles supported onto graphene substrate and nitrogen and oxygen polyacrylonitrile (PAN)-functionalized electrodes materials have been evaluated. The morphology, composition, electrochemical properties of all electrodes prepared was characterized with field emission-scanning electrode microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy and cell charge–discharge test. The presence of the CuPt3 nanocubes and nitrogen and oxygen functionalities enhance the electrocatalytic activity of the electrodes materials accelerating the oxygen and electron transfer processes. The battery performance was also evaluated using PAN-functionalized electrodes exhibiting a high of energy efficiency of 84% (at current density 20 mA cm−2) up to 30th cycle, indicating a promising alternative for improving the VFB

  12. Formation of vanadium carbide precipitations at the surface of alloys: Thermodynamics and kinetics aspects; Bildung von Vanadiumcarbid-Ausscheidungen auf Legierungsoberflaechen: Thermodynamische und kinetische Aspekte

    Schneider, A.; Uebing, C. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    The paper describes the formation of vanadium carbides on the surface layers of Fe-3%V-C(100) alloys. The phase diagram calculated for this alloyed material using the ThermoCalc program package reveals a co-existence of ferritic matrix and V{sub 3}C{sub 2} at temperatures of T{<=}650 C. This carbide is instable at elevated temperatures, leading to co-existence of ferrite and the cubic VC{sub 1-x}. Experimental analyses revealed the formation of a 2D VC compound in the top layers of the surface of Fe-3%V-C(100) alloys, induced by equilibrium segregation. The paper explains the usefulness of thermodynamic and kinetic calculations for interpretation of precipitation phenomena in steels. Mathematically derived and experimental results of analyses for the case of non-equilibrium segregation showed excellent agreement in the determination of carbide thickness (nanometer scale) and time dependence of segregation under fast cooling conditions. (orig./CB) [Deutsch] In der vorliegenden Arbeit wurde die Bildung von Vanadiumcarbiden auf Fe-3%V-C(100)-Legierungsoberflaechen beschrieben. Das anhand des ThermoCalc-Programmpakets fuer diese Legierungszusammensetzung berechnete Phasendiagramm zeigt bei niedrigen Temperaturen T{<=}650 C die Koexistenz von ferritischer Matrix und V{sub 3}C{sub 2}. Bei hoeheren Temperaturen ist dieses Carbid instabil und es liegt Koexistenz von Ferrit und dem kubischen VC{sub 1-x} vor. Die experimentellen Untersuchungen zeigen die Ausbildung einer zweidimensionalen VC-Oberflaechenverbindung auf Fe-3%V-C(100)-Legierungsoberflaechen durch Gleichgewichtssegregation. Diese Arbeit zeigt, dass thermodynamische und kinetische Rechnungen bei der Deutung von Ausscheidungsphaenomenen in Staehlen sinnvoll eingesetzt werden koennen. Bei der Nichtgleichgewichtssegregation wurde bezueglich Carbiddicke (im Nanometerbereich) und Zeitabhaengigkeit der Ausscheidung bei schneller Abkuehlung eine hervorragende Uebereinstimmung zwischen Simulation und Experiment gefunden

  13. Vanadium recycling in the United States in 2004

    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).

  14. Improvement of melting technology for vanadium-containing steel by using briquets of direct reduction

    The method of ladle alloying with vanadium is developed for commercial production of high-quality steel. Briquets of vanadium containing converter slag and low cost silicon-vanadium alloying additive 0.5 kg in mass are introduced into a ladle at steel temperature of 1620-1650 deg C in the amount of 2.7-17.0 kg per ton. This method allows vanadium assimilation up to 0.15 %. 5 refs

  15. Results of R and D for lithium/vanadium breeding blanket design

    Mattas, R.F.; Smith, D.L.; Reed, C.B.; Park, J.H. [Argonne National Lab., IL (United States); Kirillov, I.R. [D.V. Efremov Scientific Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation); Strebkov, Yu.S. [Research and Development Inst. of Power Engineering, Moscow (Russian Federation); Rusanov, A.E. [Inst. of Physics and Power Engineering, Obninsk (Russian Federation); Votinov, S.N. [A.A. Bochvar Inst. of Non-Organic Materials, Moscow (Russian Federation)

    1997-04-01

    The self-cooled lithium/vanadium blanket concept has several attractive features for fusion power systems, including reduced activation, resistance to radiation damage, accommodation of high heat loads and operating to temperatures of 650--700 C. The primary issue associated with the lithium/vanadium concept is the potentially high MHD pressure drop experienced by the lithium as it flows through the high magnetic field of the tokamak. The solution to this issue is to apply a thin insulating coating to the inside of the vanadium alloy to prevent the generation of eddy currents within the structure that are responsible for the high MHD forces and pressure drop. This paper presents progress in the development of an insulator coating that is capable of operating in the severe fusion environment, progress in the fabrication development of vanadium alloys, and a summary of MHD testing. A large number of small scale tests of vanadium alloy specimens coated with CaO and AlN have been conducted in liquid lithium to determine the resistivity and stability of the coating. In-situ measurements in lithium have determined that CaO coatings, {approximately} 5 {micro}m thick, have resistivity times thickness values exceeding 10{sup 6} {Omega}-cm{sup 2}. These results have been used to identify fabrication procedures for coating a large vanadium alloy (V-4Cr-4Ti) test section that was tested in the ALEX (Argonne Liquid metal Experiment) facility. Similar test sections have been produced in both Russia and the US.

  16. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    Guosong Sun; Qingze Huang; Shiyong Huang; Qiuping Wang; Huiquan Li; Haitao Liu; Shijie Wan; Xuewang Zhang; Jinshu Wang

    2016-01-01

    Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR) methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhil...

  17. In Vitro Antitumor Activity of a Keggin Vanadium-Substituted Polyoxomolybdate and Its ctDNA Binding Properties

    2015-01-01

    A Keggin vanadium-substituted polyoxomolybdate, K5PMo10V2O40 (PMo10V2), has been synthesized and it’s antitumor effect against Hela cells was investigated. The calf thymus DNA (ctDNA) binding ability of PMo10V2 was also evaluated by UV-Vis absorption spectra and fluorescence spectra. The identity and high purity of PMo10V2 was confirmed by elemental analysis and IR analysis. And the antitumor activity test of PMo10V2 was carried out on Hela cancer cells line by MTT assay. The results of MTT ...

  18. The rapid determination of manganese, vanadium, and aluminium by instrumental neutron-activation analysis

    Aluminium, manganese, and vanadium were determined in chromuim, ferrochromium, and slags. Because of the short-lived isotopes produced, the technique is rapid, and the total analysis time per sample is 15 minutes. The reproducibility is 3 to 4 per cent, and this value can be improved by certain modifications, particularly to the irradiation facilities. A similar method could be applied to on-line or in-plant analysis if an isotopic source of neutrons were used

  19. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D - Annual report input for 1996

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor (RD) upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy has been completed at Teledyne Wah Chang of Albany, Oregon (TWCA) to provide ∼800-kg of applicable product forms, and two billets have been extruded from the ingot. Chemical compositions of the ingot and both extruded billets were acceptable. Material from these billets will be converted into product forms suitable for components of the DIII-D Radiative Divertor structure. 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, 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

  20. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D - Annual report input for 1996

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-10-01

    V-4Cr-4Ti alloy has been selected for use in the manufacture of a portion of the DIII-D Radiative Divertor (RD) upgrade. The production of a 1200-kg ingot of V-4Cr-4Ti alloy has been completed at Teledyne Wah Chang of Albany, Oregon (TWCA) to provide {approximately}800-kg of applicable product forms, and two billets have been extruded from the ingot. Chemical compositions of the ingot and both extruded billets were acceptable. Material from these billets will be converted into product forms suitable for components of the DIII-D Radiative Divertor structure. 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, 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.

  1. Synthesis and characterization of vanadium doped SnO{sub 2} diluted magnetic semiconductor nanoparticles with enhanced photocatalytic activities

    Mazloom, J. [Department of Physics, Faculty of Science, University of Guilan, Namjoo Avenue, P.O. Box 413351914, Rasht (Iran, Islamic Republic of); Ghodsi, F.E., E-mail: feghodsi@guilan.ac.ir [Department of Physics, Faculty of Science, University of Guilan, Namjoo Avenue, P.O. Box 413351914, Rasht (Iran, Islamic Republic of); Golmojdeh, H. [Department of Chemistry, Faculty of Science, University of Guilan, Namjoo Avenue, P.O. Box 413351914, Rasht (Iran, Islamic Republic of)

    2015-08-05

    Highlights: • Pure and V-doped SnO{sub 2} nanoparticles were synthesized using a facile sol–gel route. • The V{sup 4+} ions were incorporated into the SnO{sub 2} lattice and located at the Sn{sup 4+} sites. • TEM images reveled that by increasing the doping content, average grain size decreased. • We show that the V-doped SnO{sub 2} is more photoactive than undoped SnO{sub 2}. • The V-doped SnO{sub 2} nanoparticles exhibited ferromagnetism at room temperature. - Abstract: Vanadium doped SnO{sub 2} nanoparticles were synthesized by a facile sol–gel method. Different analytical techniques including TG/DTG, XRD, XPS, VSM and PL were used to investigate the influence of dopant concentration on structural, morphological, compositional, magnetic and optical properties of prepared nanoparticles. The XRD study showed a dominant tetragonal structure. The X-ray photoelectron spectroscopy proved the presence of vanadium as V{sup 4+} species. TEM image revealed that particle size decrease by doping. It was found that room temperature ferromagnetic (RTFM) behavior is strongly dependent on vanadium dopant content and the magnetic saturation dropped rapidly with increasing V content, which can be explained reasonably through bound magnetic polaron (BMP) model. A quenching in green luminescence intensity was observed in V-doped SnO{sub 2} compared to undoped sample. The 5% V-doped SnO{sub 2} sample showed better photocatalytic activity than undoped one in decomposing methylene blue and rhodamine B.

  2. Neutron activation analysis of zirconium niobium alloys

    Full text: One of the important problems in nuclear reactor projecting is the choice of constructional materials, which meet to the requirements concerned with function, technical characteristics and expected performance of the reactor construction. Also it is necessary to take into account change of their properties under the influence of intensive neutron radiation. Zirconium and zirconium-niobium alloys are used in nuclear engineering as a fuel cladding and both matrix and impurity composition have an influence on their performance capabilities.Under intensive neutron radiation high content of undesirable trace elements in constructional materials can cause forming long-lived radionuclides with high induced activity and hence severe problems may occur at service, control of the equipment and carrying out experiments. Therefore analytical control of component and impurity composition of these materials is an important problem.Neutron activation analysis (NAA) is one of multielemental and high sensitivity methods, which widely applied for the analysis of high purity materials. Prior experiments have shown that instrumental NAA is not suitable for analysis of Zr-Nb alloys due to strong induced matrix activity. Therefore we have developed radiochemical procedure for separation of impurities from matrix elements. Study of the literature data has shown that zirconium and niobium are good extracted from hydrochloric medium by 0 75 M solution of di-2-ethylhexylphosphoric acid (DEHPA) in ortho-xylene. Also this system good extracts hafnium which being accompanying element has high content and interferes with determining impurity elements. To improve separation efficiency we have used 'DEHPA - ZM HCl' chromatography system. On the basis of the carried out researches the radiochemical NAA technique for analysis of high purity zirconium and zirconium-niobium alloys has been developed. The technique is based on extraction-chromatographic separation of matrix radionuclides

  3. Development of irradiation capsules in liquid metal environment in Joyo and their application to irradiation creep measurement of vanadium alloys

    In order to perform irradiation experiments in a liquid metal environment in a nuclear reactor, an irradiation technique with sodium bonding irradiation capsules was developed and a series of neutron irradiation experiments with sodium bonding irradiation capsules were performed in Joyo. The design and fabrication of sodium bonding capsules, sodium filling into capsules, capsule loading to Joyo, irradiation experiments, dismantling for irradiated capsules, removing the irradiated specimens from sodium-filled capsules, and sodium cleaning of the irradiated specimens were established through this study. Using the Joyo irradiation with the sodium bonding capsules where irradiation temperature was distributed uniformly, the irradiation creep experiment for highly purified V-4Cr-4Ti alloys, NIFS-Heat, was carried out and the knowledge about the irradiation creep behavior of the alloys was obtained. (author)

  4. Tensile and impact properties of vanadium-base alloys irradiated at low temperatures in the ATR-A1 experiment

    Tsai, H.; Nowicki, L.J.; Billone, M.C.; Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)

    1998-03-01

    Subsize tensile and Charpy specimens made from several V-(4-5)Cr-(4-5)Ti alloys were irradiated in the ATR-A1 experiment to study the effects of low-temperature irradiation on mechanical properties. These specimens were contained in lithium-bonded subcapsules and irradiated at temperatures between {approx}200 and 300 C. Peak neutron damage was {approx}4.7 dpa. Postirradiation testing of these specimens has begun. Preliminary results from a limited number of specimens indicate a significant loss of work-hardening capability and dynamic toughness due to the irradiation. These results are consistent with data from previous low-temperature neutron irradiation experiments on these alloys.

  5. Preparation and electrochemical activities of iridium-decorated graphene as the electrode for all-vanadium redox flow batteries

    This study reports the preparation of iridium-decorated graphene (Ir-G) as an electrode material for an all-vanadium redox flow battery (VRB) by synchronously reducing graphite oxide (GO) and iridium chloride hydrate (IrCl3·3H2O). X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution X-ray photoelectron spectroscopy (XPS) were employed to characterize the physicochemical properties of Ir-G. Cyclic voltammetry (CV) was used to measure the electrochemical behaviors of the Ir-G for the VRB system. In addition, this study investigated and compared the electrochemical behaviors of graphene with those of Vulcan XC-72. The Ir nanoparticles were exclusively deposited on graphene surface with high uniformity and a mean size of 3 nm. The CV results reveal that Ir-G possesses a highly electrocatalytic activity and reversibility among all samples. In addition, the redox current densities of Ir-G are approximately four times higher than those of XC-72. The large electrolyte-accessible surface area and intense affinity of Ir/vanadium-oxygen ions that facilitate electronic and ionic transport contribute to these improvements. Therefore, this study proposes a synchronous reduction method for preparing an Ir-G electrode that exhibits excellent electrocatalytic performance, thereby demonstrating significant improvements in VRB applications.

  6. Assimilation characteristics of vanadium ferroalloys in liquid steel

    The assimilation characteristics of various vanadium ferroalloys were identified in a ''dynamic way'' using the load cell technique. The ferrovanadium alloys which have a vanadium content less than 68 wt % belong to class 1 ferroalloys. They utilize a melting mechanism during their assimilation in liquid steel. The ferrovanadium alloys which have a vanadium content greater than 68 wt % belong to class 2 ferroalloys. These follow a dissolution mechanism during their assimilation in liquid steel. Their mass transfer kinetics is at least seven times slower than the previously mentioned ferrovanadium alloys

  7. Vanadium and zirconium effects on rolling and recrystallization texture and on Young modulus anisotropy in Ti-V and Ti-Zr alloys

    Using the method of building the direct pole figures [0002] and [10 anti 10] formation of cold rolling texture and the change of the main orientations during heat treatment of different alloys Ti-V and Ti-Zr are studied. Evaluation of Young modulus anisotropy is made. It is shown that cold rolling forms monocomponent texture in the alloys, and when Zr content is above 45% - a two-component one. Texture distinctness and increase of Young modulus anisotropy during annealings are connected with the active proceeding of polygonization processes

  8. Comparison of hypoglycemic activity of fermented mushroom of Inonotus obliquus rich in vanadium and wild-growing I. obliquus.

    Zhang, Yibing; Zhao, Yong; Cui, Haifeng; Cao, Chunyu; Guo, Jianyou; Liu, Sha

    2011-12-01

    The effects of vanadium-enriched and wild Inonotus obliquus were tested on hyperglycemic mice. The vanadium content of the culture medium was 0.6%, reaching a concentration of 3.0 mg/g in the cultured mushroom while in the wild variety is 1/100 of that amount. The toxicity of vanadium at the 3.0 mg/g level is negligible, but its anti-diabetic effects are significantly different to those of the wild variety (p obliquus could be used as a means of vanadium supplementation, with expectation of obtaining higher bioavailability and lower toxicity in animals. PMID:21465283

  9. FIA versatile system for spectrophotometric determinations of vanadium and molybdenum exploring the catalytic activities of V(V) and Mo(VI)

    A versatile system for chemical analysis by flow injection analysis was developed and applied for catalytic spectrophotometric determination of vanadium or molybdenum in metallic alloys. The selected methods were based upon indicator reactions chromotropic (CS)-bromate acid or hydrogen iodide-peroxide, respectively. Initially, a model system was proposed, in which common parameters for methods were studied. This included a re-sampling process in which high degrees of samples dilution were obtained. Other parameters such as concentrations and reagents addition order, reaction medium Ph, temperature and ionic power, as well as procedures for sample solubilization, were studied relating to each method. A mini-column with cationic exchanger resin (Dowex 50W-X8, 50-100 mesh, H+ form) was used. The system for vanadium determination processes 120 samples by hour, consuming 2,0 mg CS and 10 mg K Br O3by determination. Concerning the method for molybdenum, the reagents consumption was 2,0 mg KI and 1,0 μL of solution 30% H2O2 by determination, since the analytic velocity was the same, in relation to vanadium

  10. Selective determination of vanadium using N-benzoyl-N-phenylhydroxylamine

    Technique for selective spectrophotometric vanadium determination in alloys after extraction by chloroform of vanadium (5) complexes with N-benzoyl-N-phenylhydroxylamine from phosphoric acid solutions was developed. Low boundary of determination on sample dissolving ∼1 h. Effect of the nature of mineral acids and aliphatic alcohols on spectrophotometric characteristics of complexes was investigated

  11. Composite Nickel Coatings Produced on 6XXX Series Aluminium Alloys with the Addition of Vanadium / Kompozytowe Powłoki Niklowe Wytwarzane Na Stopach Aluminum Serii 6XXX Z Dodatkiem Wanadu

    Nowak M.

    2015-12-01

    Full Text Available Studies of composite nickel coatings electrolytically deposited on aluminium alloys with different content of vanadium were described. Composite coatings were deposited from a Watts bath containing fine-dispersed SiC powder particles in an amount of 20 g/l and organic matters such as saccharin and sodium laurate. The morphology, structure and thickness of the obtained composite coatings were presented. The corrosion resistance of produced coatings was examined by electrochemical method. Basing on the results of studies it was found that coatings obtained with the sole addition of saccharin were characterized by numerous surface defects. The addition of sodium laurate eliminated the occurrence of defects caused by hydrogen evolution and the resulting coatings were continuous with good adhesion to the substrate. The distribution of the ceramic SiC phase in coatings was fairly uniform for all the examined variants of aluminium alloys. SEM examinations did not reveal the phenomenon of the ceramic particles agglomeration.

  12. Revealing the low-temperature effect of strengthening the magnetism of iron-vanadium-aluminum alloy upon small variation of the non-transition element content in the stoichiometric composition

    Lonchakov, A. T.; Marchenkov, V. V.; Okulov, V. I.; Govorkova, T. E.; Okulova, K. A.; Bobin, S. B.; Deryushkin, V. V.; Emel'yanova, S. M.; Usik, A. Yu.; Weber, H. W.

    2016-03-01

    Anomalously strong change of ferromagnetic ordering parameters upon a small variation of aluminum content was revealed in low-temperature experimental studies of electrical resistivity and galvanomagnetic properties of iron-vanadium-aluminum magnetic alloys with the compositions near the stoichiometric Fe2VAl. By comparing the temperature and magnetic field dependences of the electrical resistivity and Hall effect in Fe2.1V0.91Al0.99 and Fe2.05V0.91Al1.04 alloys, it was shown that a small increase of aluminum content leads to doubling of the Curie temperature and a sharp change in the temperature dependences of the magnetoresistance and saturation of the spontaneous magnetization.

  13. Behaviour of Al2O3 scales on Fe-Al and Fe-Ni-Al alloys with small additions of titanium, zirconium, niobium and vanadium on thermal cycling and creep in oxidizing and carburizing atmospheres

    Aluminium as an alloying element in steels is beneficial for the formation of slow-growing oxide layers at high temperatures. Steels with aluminium as the oxide former are of interest for use in carburizing atmospheres with low O2 partial pressures, e.g. coal gasification or the high temperature nuclear reactor. The behaviour of Al2O3 layers on ferritic and austenitic steels with small additions of titanium, zirconium, niobium and vanadium was studied by measuring radiocarbon penetration in thermal cycling and creep experiments. The oxide layers on the ferritic steels adhered well and were compact with a high carburization resistance. In the creep tests on the austenitic alloys, cracking of the oxide layer and subsequent intergranular oxidation and carburization were observed. (orig.)

  14. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb2O5)N+ clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb2O5)N+ clusters decreases as the N increases, and it is higher than that of (V 2O5)N+ for N ≥ 4. Theoretical studies were conducted on (Nb2O5)N+ (N = 2–6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion

  15. Vanadium in soils

    Larsson, Maja A

    2014-01-01

    Vanadium is a redox-sensitive metal that is released to soils by weathering and anthropogenic emissions. Swedish metallurgical slags are naturally high in vanadium and used as soil amendments and in road materials. However, understanding of vanadium chemistry and bioavailability in soils is limited. The aim of this thesis was to provide knowledge of vanadium in soils in terms of sorption, toxicity and speciation, in order to enable improved environmental risk assessments. Vanadium sorption to...

  16. Vanadium carbide coatings: deposition process and properties

    Vanadium carbide coatings on carbon and alloyed steels were produced by the method of diffusion saturation from the borax melt. Thickness of the vanadium carbide layer was 5-15 μm, depending upon the steel grade and diffusion saturation parameters. Microhardness was 20000-28000 MPa and wear resistance of the coatings under conditions of end face friction without lubrication against a mating body of WC-2Co was 15-20 times as high as that of boride coatings. Vanadium carbide coatings can operate in air at a temperature of up to 400 oC. They improve fatigue strength of carbon steels and decrease the rate of corrosion in sea and fresh water and in acid solutions. The use of vanadium carbide coatings for hardening of various types of tools, including cutting tools, allows their service life to be extended by a factor of 3 to 30. (author)

  17. Methane Activation Mediated by a Series of Cerium-Vanadium Bimetallic Oxide Cluster Cations: Tuning Reactivity by Doping.

    Ma, Jia-Bi; Meng, Jing-Heng; He, Sheng-Gui

    2016-04-18

    The reactions of cerium-vanadium cluster cations Cex Vy Oz (+) with CH4 are investigated by time-of-flight mass spectrometry and density functional theory calculations. (CeO2 )m (V2 O5 )n (+) clusters (m=1,2, n=1-5; m=3, n=1-4) with dimensions up to nanosize can abstract one hydrogen atom from CH4 . The theoretical study indicates that there are two types of active species in (CeO2 )m (V2 O5 )n (+) , V[(Ot )2 ](.) and [(Ob )2 CeOt ](.) (Ot and Ob represent terminal and bridging oxygen atoms, respectively); the former is less reactive than the latter. The experimentally observed size-dependent reactivities can be rationalized by considering the different active species and mechanisms. Interestingly, the reactivity of the (CeO2 )m (V2 O5 )n (+) clusters falls between those of (CeO2 )2-4 (+) and (V2 O5 )1-5 (+) in terms of C-H bond activation, thus the nature of the active species and the cluster reactivity can be effectively tuned by doping. PMID:26714587

  18. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides.

    Ding, Xun-Lei; Wang, Dan; Wu, Xiao-Nan; Li, Zi-Yu; Zhao, Yan-Xia; He, Sheng-Gui

    2015-09-28

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb2O5)N(+) clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb2O5)N(+) clusters decreases as the N increases, and it is higher than that of (V 2O5)N(+) for N ≥ 4. Theoretical studies were conducted on (Nb2O5)N(+) (N = 2-6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion. PMID:26429016

  19. 钒合金与钢异种材料焊接研究现状分析%Research status analysis on welding technology of vanadium alloy to steel

    王亚荣; 滕文华; 杨家林; 余洋

    2012-01-01

    The research status of welding technology of vanadium alloy to steel was summarized by taking the brazing, pressure welding and fusion welding as the main study body. The present results show that the oxidation film on the material surface and the brittle intermetallic compounds formed in the welding process are the key factors to influence the joint properties. The effective solution methods were proposed. It was found that the proper filler materials such as Au -Ni, V, Nd, and so on exhibit good wettability with vanadium alloy on stainless steel, which help to improve the weld quality. The metallurgical bonded joints were developed by several solid - state joining, such as explosive welding or friction welding. In order to minimize the formation of intermetallics, the reaction between liquid metal and solid metal can be precisely controlled by brazing the stainless steel with the lower melting point to the vanadium alloy with higher melting point.%以钎焊、压焊和熔焊为研究主体,综述了钒合金与钢的连接技术研究进展.现有的研究成果表明,钒合金与钢的连接存在着很大的难度,材料表面氧化膜、结合界面形成的脆性金属间化合物是影响接头性能的关键.解决的有效途径是:选择合适的中间层材料,如Au-Ni,V,Nb等,可以很好地润湿钒合金与钢以提高接头性能;采用爆炸焊或摩擦焊的固相连接手段,避免金属的熔化;采用熔化低熔点金属润湿-钎接高熔点金属的方法精确控制材料之间的反应,将产生金属间化合物的可能性降至最低,以实现异种金属间的可靠连接.

  20. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    Guosong Sun

    2016-03-01

    Full Text Available Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD, N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhile, the catalytic activity of VOx/MSU-1 was investigated, and VOx/MSU-1 with 12.0 wt. % VOx content was found to be the best one, with the conversion of isobutane (58.8% and the selectivity of isobutene (78.5% under the optimal reaction conditions. In contrast with the reaction in the absence of CO2, the presence of CO2 in the reaction stream could obviously enhance the isobutane dehydrogenation, which raised the conversion of reaction and the stability of VOx/MSU-1.

  1. Study on Determination Method of Nitrogen in Vanadium-Nitrogen Alloy with Nitrogen Oxygen Meter%氮氧仪测定钒氮合金中氮的方法研究

    程张生; 张亚红; 侯社林; 郭少毅

    2014-01-01

    Using the EMGA-800/SP nitrogen oxygen analyzer , adding tin-nickel fluxing agent , adopting the impulse-heat-ing and thermal conductivity method , rapid analysis method of nitrogen in vanadium-nitrogen alloy was developed with measuring range:1.00%~20.00%.The method is simple in operation , accurate in data .The relative standard deviation is RSD≤1%.%利用EMGA-800W/SP氮氧分析仪,添加锡-镍助熔剂,采用脉冲加热-热导法研制了钒氮合金中氮的快速分析方法。测量范围:1.00%~20.00%。该方法操作简便,数据准确。相对标准偏差RSD≤1%。

  2. Spectrophotometric determination of vanadium after extraction as vanadium(III) picolinate.

    Yatirajam, V; Arya, S P

    1979-01-01

    Vanadium(V) is conveniently reduced by sodium dithionite to vanadium(III) which is extracted as its picolinate complex into chloroform. Vanadium is determined spectrophotometrically by measuring the absorbance of the complex at 385 nm against a reagent blank, Beer's law being obeyed over the range 1-50 microg/ml. The method is one of the most selective, being free from interference by relatively high concentrations of almost all the important elements, titanium, chromium, manganese, iron, cobalt, nickel, zinc, copper, aluminium, molybdenum, tungsten and uranium, found in industrial alloys. Only bismuth interferes. The method is quite simple and rapid. It has been successfully applied for the analysis of vanadium in a variety of samples. PMID:18962377

  3. Activation of Janus kinase/signal transducers and activators of transcription pathway involved in megakaryocyte proliferation induced by vanadium resembles some aspects of essential thrombocythemia.

    Gonzalez-Villalva, Adriana; Piñon-Zarate, Gabriela; Falcon-Rodriguez, Carlos; Lopez-Valdez, Nelly; Bizarro-Nevares, Patricia; Rojas-Lemus, Marcela; Rendon-Huerta, Erika; Colin-Barenque, Laura; Fortoul, Teresa I

    2016-05-01

    Vanadium (V) is an air pollutant released into the atmosphere by burning fossil fuels. Also, it has been recently evaluated for their carcinogenic potential to establish permissible limits of exposure at workplaces. We previously reported an increase in the number and size of platelets and their precursor cells and megakaryocytes in bone marrow and spleen. The aim of this study was to identify the involvement of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway and thrombopoietin (TPO) receptor, and myeloproliferative leukemia virus oncogene (Mpl), in megakaryocyte proliferation induced by this compound. Mice were exposed twice a week to vanadium pentoxide inhalation (0.02 M) and were killed at 4th, 6th, and 8th week of exposure. Phosphorylated JAK2 (JAK2 ph), STAT3 (STAT3 ph), STAT5, and Mpl were identified in mice spleen megakaryocytes by cytofluorometry and immunohistochemistry. An increase in JAK2 ph and STAT3 ph, but a decrease in Mpl at 8-week exposure was identified in our findings. Taking together, we propose that the morphological findings, JAK/STAT activation, and decreased Mpl receptor induced by V leads to a condition comparable to essential thrombocythemia, so the effect on megakaryocytes caused by different mechanisms is similar. We also suggest that the decrease in Mpl is a negative feedback mechanism after the JAK/STAT activation. Since megakaryocytes are platelet precursors, their alteration affects platelet morphology and function, which might have implications in hemostasis as demonstrated previously, so it is important to continue evaluating the effects of toxics and pollutants on megakaryocytes and platelets. PMID:24442345

  4. Activation of vanadium-based Ziegler-Natta catalysts by halocarbons for ethylene polymerization: results and mechanism

    The reactions for the low productivity of the heterogeneous and homogenous V-based catalysts in the synthesis of LLDPE were discussed and some routes of improving their activity and stability were proposed. Ethylene polymerizations were performed in the isododecane solutions at 160 C and under constant ethylene pressure of 5 bars. One Ti-based catalytic system (TiCl3 - 0.3 AlCl3) and two V-based systems (TiCl3 - 0.3 AlCl3 and VCl4) were investigated. The main reason of activity loss is a rapid reduction of V4+ and V3+ to inactive V2+ form. AlR3 cocatalysts are also involved in the deactivation process. The effect of addition to the system of various alkyl halides (a.o. of CCl4, CH3Cl3, CF3CCCl3, CHCl3, CHBr3, CH2Cl2, CH2BrCl and CH2Br2) on the yield of polyethylene was investigated. The alkyl halides act as efficient activators for the heterogeneous and homogeneous vanadium catalysts in the high temperature ethylene polymerization and its copolymerization with 1-hexane. The effect of the presence of CHCl3 on the short chain branching and the molecular weight distribution (GPC) of these copolymers was also investigated. Halocarbons do not act as chain transfer agents. The peak molecular weight remains almost unchanged but a narrowing of molecular weight distribution is observed due to the suppression of the amount of high-molecular-weight fraction in polymer. (author). 4 refs, 3 figs, 2 tabs

  5. Effect of the composition of Ti alloy on the photocatalytic activities of Ti-based oxide nanotube arrays prepared by anodic oxidation

    Tang, Dingding, E-mail: 13396064706@163.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Wang, Yixin, E-mail: 821314137@qq.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Zhao, Yuwei, E-mail: 412494599@qq.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yang, Yijia, E-mail: newyang214@126.com [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Zhang, Lieyu, E-mail: zhanglieyu@163.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China)

    2014-11-15

    Highlights: • Effect of Ti alloy composition on the properties of TiO{sub 2} nanotube arrays is studied. • Al and V decrease the growth rate of nanotube arrays and deteriorate the performance. • Nanotube arrays derived from Ti–0.2Pd alloy exhibit enhanced photocatalytic activity. • Nanotube arrays derived from Ti–0.2Pd alloy have preferable stability. • Anodization of Ti alloys provides a way to prepare high-performance doped titania. - Abstract: Three types of Ti-based oxide nanotube arrays are prepared by anodic oxidation of pure Ti and Ti alloys (Ti–0.2Pd and Ti–6Al–4V) in the glycol–2 wt% H{sub 2}O–0.3 wt% NH{sub 4}F solution. The nanotube arrays are characterized by a series of techniques, including SEM, TEM, EIS, XRD, EDS, ICP, XPS and UV–vis DRS, to elucidate the effect of alloying elements on the properties of titania nanotube arrays. The results suggest that aluminium and vanadium elements greatly slow down the growth rate and therefore decrease the yield of nanotube arrays. Al and V deteriorate the photoreactivity of the resultant nanotube arrays. The palladium inside the Ti–0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Pd significantly improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the separation of photogenerated charge carriers. The uniform doping of Pd into the microstructure endows nanotube arrays with resistance to sulphur poison and preferable stability for organic degradation. This study suggests that anodization of Ti alloys, rather than pure Ti metal, allows to produce micron-sized high-performance photocatalysts for environmental and energy applications.

  6. Effect of the composition of Ti alloy on the photocatalytic activities of Ti-based oxide nanotube arrays prepared by anodic oxidation

    Highlights: • Effect of Ti alloy composition on the properties of TiO2 nanotube arrays is studied. • Al and V decrease the growth rate of nanotube arrays and deteriorate the performance. • Nanotube arrays derived from Ti–0.2Pd alloy exhibit enhanced photocatalytic activity. • Nanotube arrays derived from Ti–0.2Pd alloy have preferable stability. • Anodization of Ti alloys provides a way to prepare high-performance doped titania. - Abstract: Three types of Ti-based oxide nanotube arrays are prepared by anodic oxidation of pure Ti and Ti alloys (Ti–0.2Pd and Ti–6Al–4V) in the glycol–2 wt% H2O–0.3 wt% NH4F solution. The nanotube arrays are characterized by a series of techniques, including SEM, TEM, EIS, XRD, EDS, ICP, XPS and UV–vis DRS, to elucidate the effect of alloying elements on the properties of titania nanotube arrays. The results suggest that aluminium and vanadium elements greatly slow down the growth rate and therefore decrease the yield of nanotube arrays. Al and V deteriorate the photoreactivity of the resultant nanotube arrays. The palladium inside the Ti–0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Pd significantly improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the separation of photogenerated charge carriers. The uniform doping of Pd into the microstructure endows nanotube arrays with resistance to sulphur poison and preferable stability for organic degradation. This study suggests that anodization of Ti alloys, rather than pure Ti metal, allows to produce micron-sized high-performance photocatalysts for environmental and energy applications

  7. Experimental study on activating welding for aluminum alloys

    Huang Yong; Fan Ding

    2005-01-01

    TIG welding and EB welding for aluminum alloy 3003 were carried out to study the effects of activating flux on weld penetration of activating welding for aluminum alloys. SiO2 was used as the activating flux. It is found that, SiO2 can increase the weld penetration and decrease the weld width of FBTIG when the flux gap is small. For A-TIG welding and EB welding with focused mode, the weld penetrations and the weld widths increase simultaneously. SiO2 has little effect on the weld penetration and weld width of EB welding with defocused mode. It is believed that, change of surface tension temperature gradient is not the main mechanism of SiO2 improving weld penetration of activating welding for aluminum alloys.

  8. Superficial effects during the activation of zirconium AB2 alloys

    The activation of zirconium nickel alloys with and without the addition of chromium and titanium is investigated through electrochemical and optical techniques.These alloys show high hydrogen absorption capacity and are extensively used in metal hydride batteries.Recent investigations in aqueous 1 M KOH indicate oxide layer growth and occlusion of hydrogen species in the alloys during the application of different cathodic potential programmes currently used in the activation process.In this research several techniques such as voltammetry, ellipsometry, energy dispersive analysis of X-rays EDAX, and scanning electron microscopy SEM are applied on the polished massive alloy Zr1-xTix, x=0.36 y 0.43, and Zr1-xTixCrNi, x=0.1,0.2 y 0.4.Data analysis shows that the stability, compactness and structure of the passive layers are strongly dependent on the applied potential programme.The alloy activation depends on the formation of deepen crevices that remain after a new polishing. Microscopic observation shows increase in the crevices thickness after the cathodic sweep potential cycling, which produces fragmentation of the grains and oxide growth during the activation process.This indicates metal breaking and intergranular dissolution that take place together with oxide and hydride formation.In some cases the resultant crevice thickness is one or two orders higher than that of the superficial oxide growth indicating intergranular localised corrosion

  9. Titanium and vanadium ethylene polymerization catalysts containing tris(pyrazolyl)borate ligand: Effects of polymerization parameters on activity and polymer properties

    The ethylene polymerization behavior of a series of titanium(IV) and vanadium(V) complexes, [Tp'MXCl2] (1, M= Ti, Tp'= TpMs*, X = Cl; 2, M Ti, Tp'= TpMs, X = Cl; 3, M = V, Tp'= TpMs*, X = NtBu; 4, M = V, Tp'TpMs*, X = NAr) (TpMs*HB(3-mesityl-pyrazolyl)2(5-mesityl-pyrazolyl), TpMs HB(3-mesityl-pyrazolyl)3, Ar = 2,6-iPr2-C6 H3) was investigated in toluene or hexane using MAO or TiBA/MAO (1:1) as activators, and varying the polymerization temperature. The polymerization results showed that independently of the catalysts precursors used in the polymerization run, higher activities were found using TiBA/MAO/hexane system. For titanium species, the maximum catalytic activities were reached at 60 deg C while for vanadium ones the highest activities were attained at 30 deg C. Studies related to the influence of the [Al]/[M] molar ratio (M = Ti, V) have shown that these catalyst precursors presented highest activities using Al concentrations as low as 50:1. DSC curves showed the production of linear polyethylene with melting temperature in the range of 123-140 deg C. The viscosity average molecular weights of the polyethylenes are in the range of 7 x 103-16.4 x 106 g mol-1. (author)

  10. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe......, V and oxygen where at least some of the V is in the tetravalent state. USE-(I) is a cathode active material in electric current producing storage cells. ADVANTAGE-Use of (I) in Li or alkali metal batteries gives prolonged life cycles.Storage cells using (I) have improved capacity during charge and...

  11. Delayed Fracture Behavior of CrMo Type High Strength Steel Containing Vanadium

    HUI Wei-jun; DONG Han; WENG Yu-qing

    2003-01-01

    The effect of microalloying element vanadium on hydrogen-induced delayed fracture behavior of quenched and tempered low alloy CrMo type steel in Walpole aqueous solution was investigated. The sustained load tensile test was carried out by using notched tensile specimens. The experimental results show that the suitable addition of vanadium is effective in improving delayed fracture resistance. The finely dispersed precipitation of vanadium carbide causes a significant secondary hardening, so the tempering temperature of steel containing vanadium is higher than that of the base steel at the same strength level. This homogeneously distributed carbide acts as strong hydrogen trap, thus retards the diffusion and accumulation of hydrogen and avoids the entering of hydrogen into stress concentration site. These beneficial effects of vanadium carbide are the main reasons for the improvement of delayed fracture resistance of steel containing vanadium. Furthermore, the fine prior austenite grain of steel with suitable addition of vanadium is also an important factor for the improvement.

  12. Enhancement in Activity of a Vanadium Catalyst for the Oxidation of Sulfur Dioxide by Radio Frequency Plasma During the Preparation Process

    Zhenxing Chen; Honggui Li; Lingsen Wang

    2003-01-01

    Radio frequency plasma was used to prepare a vanadium catalyst. The results showed that activating time of the catalyst could be shortened quickly and the catalytic activity was improved to some extent with the use of plasma. Catalyst Ls-9 was prepared under an optimal condition of 40 W discharge power, 10 min discharge time and 8 Pa gas pressure. The catalytic activity was up to 54.7% at 410 ℃,which was 2.2% higher than that of the Ls-8 catalyst. Only 10 min was needed to activate the catalyst with plasma, which was 1/9 of the traditional calcination time. For Ls-9, both the endothermic as well as the exothermic peaks detected by differential thermal analysis shifted to higher temperatures obviously,indicating that its crystal phase could melt easily. There existed an apparent endothermic peak at 283 ℃. SEM photographs showed a uniform size distribution. It is inferred that the quadrivalent vanadium compound may exist mainly in the form of VOSO4.

  13. Macromolecular peroxo complexes of Vanadium(V) and Molybdenum(VI): Catalytic activities and biochemical relevance

    Nashreen S Islam; Jeena Jyoti Boruah

    2015-05-01

    Our recent achievements concerning the synthesis and characterization of water soluble peroxo complexes of V(V) and Mo(VI) in macroligand environment, as well as some key features of biological relevance of these compounds, such as their hydrolytic stability, activity with phosphohydrolase enzyme vis-à-vis free peroxovanadium (pV) or peroxomolybdenum (pMo) complexes, and their activity in biomimetic oxidative bromination are presented here. Immobilization of pMo species on insoluble polymer matrices viz., amino acid functionalized Merrifield resins and poly(acrylonitrile) on the other hand, afforded a set of heterogeneous catalysts highly effective in facile organic transformations such as selective oxidation of organic sulfides and oxidative bromination of aromatic substrates by H2O2, at ambient temperature. The methodologies are straightforward, high-yielding, halogen-free and the catalysts afford easy regeneration. Our findings illustrate the various features which make the procedures sustainable and synthetically useful.

  14. Vanadium recovery process

    A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 6000C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 8000C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining

  15. One-step pickling-activation before magnesium alloy plating

    WANG Xin-juan; YU Gang; OUYANG Yue-jun; HE Xiao-mei; ZHANG Jun; YE Li-yuan

    2009-01-01

    A one-step pickling-activation process was proposed as an environmental friendly pretreatment method in phosphate-permanganate solution before electroplating on magnesium alloys. The effects of pickling-activation on qualities of coating were assessed by adhesion and porosity testing of copper plating. The interfacial reactions between specimen and solution were analyzed with SEM, EDX and XRD. The results show that the developed process of pickling-activation can equalize the potentials on substrate surface. The compacted zinc film can be obtained by zinc immersion after treating magnesium alloy in the pH 4-6 phosphate-permanganate solution for 3-5 min. The adhesion and corrosion resistance of copper plating are enhanced. The one-step pickling-activation can replace the existing two-step process of acid pickling and activation which contains a great deal of chromium and fluorine. The procedure of surface pretreatment is simplified and the production environment is improved.

  16. Activation of vanadium nitrogenase expression in Azotobacter vinelandii DJ54 revertant in the presence of molybdenum.

    Lei, S; Pulakat, L; Gavini, N

    2000-09-29

    Azotobacter vinelandii carries three different and genetically distinct nitrogenase systems on its chromosome. Expression of all three nitrogenases is repressed by high concentrations of fixed nitrogen. Expression of individual nitrogenase systems is under the control of specific metal availability. We have isolated a novel type of A. vinelandii DJ54 revertant, designated A. vinelandii BG54, which carries a defined deletion in the nifH gene and is capable of diazotrophic growth in the presence of molybdenum. Inactivation of nifDK has no effect on growth of this mutant strain in nitrogen-free medium suggesting that products of the nif system are not involved in supporting diazotrophic growth of A. vinelandii BG54. Similar to the wild type, A. vinelandii BG54 is also sensitive to 1 mM tungsten. Tn5-B21 mutagenesis to inactivate the genes specific to individual systems revealed that the structural genes for vnf nitrogenase are required for diazotrophic growth of A. vinelandii BG54. Analysis of promoter activity of different nif systems revealed that the vnf promoter is activated in A. vinelandii BG54 in the presence of molybdenum. Based on these data we conclude that A. vinelandii BG54 strain utilizes vnf nitrogenase proteins to support its diazotrophic growth. PMID:11018539

  17. Low-crystalline β-FeOOH and vanadium ferrite for positive active materials of lithium secondary cells

    Funabiki, Atsushi; Yasuda, Hideo; Yamachi, Masanori

    Low-crystalline β-FeOOH and vanadium ferrite were prepared by a simple hydrolysis method. XRD measurement revealed that the former material had a framework of β-FeOOH with somewhat amorphous structure, and that the latter one gave a crystalline structure analogous to that of the hydrated iron orthovanadate. From the electrochemical measurements, it was found that the low-crystalline β-FeOOH positive electrode showed a discharge capacity of 230 mAh/g in the potential range of 4.3 V and 1.6 V versus Li/Li +, and better cycle performance than the high-crystalline one. The vanadium ferrite positive electrode also showed a high discharge capacity over 300 mAh/g and superior cycle performance.

  18. Microadditions of boron and vanadium in ADI

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  19. Summary report for ITER task - D4: Activation calculations for the lithium vanadium ITER design

    Detailed activation analysis for ITER has been performed as a part of ITER Task D4. The calculations have been performed for the shielding blanket (SS/water) and for the breeding blanket (Li/V) options. The activation code RACC-P, which has been modified under ITER Task-D-10 for pulsed operation, has been used in this analysis. The spatial distributions of the radioactive inventory, decay heat, biological hazard potential, and the contact dose were calculated for the two designs for different operation modes and targeted fluences. A one-dimensional toroidal geometrical model has been utilized to determine the neutron fluxes in the two designs. The results are normalized for an inboard and outboard neutron wall loading of 0.91 and 1.2 MW/m2, respectively. The point-wise distributions of the decay gamma sources have been calculated everywhere in the reactor at several times after the shutdown of the two designs and are then used in the transport code ONEDANT to calculate the biological dose everywhere in the reactor. The point-wise distributions of all the responses have also been calculated. These calculations have been performed for neutron fluences of 3.0 MWa/m2, which corresponds to the target fluence of ITER, and 0.1 MWa/m2, which is anticipated to correspond to the beginning of the extended maintenance period. The decay heat results show that a large fraction of this energy (50 to 90%) Is produced by photons. This implies that this energy would be transported to different parts of the reactor, thus relieving the energy concentration at high intensity source locations such as the first wall. Accurate modeling for the decay gamma transport is required to produce realistic spatial distribution of the decay heat which may be used in LOCA and LOFA analyses. The results of the pulsed operation, using the new version of RACC, show large reductions in the radioactivity and the decay heat for pure pulsed operation

  20. Vanadium Compounds as Pro-Inflammatory Agents: Effects on Cyclooxygenases

    Jan Korbecki; Irena Baranowska-Bosiacka; Izabela Gutowska; Dariusz Chlubek

    2015-01-01

    This paper discusses how the activity and expression of cyclooxygenases are influenced by vanadium compounds at anticancer concentrations and recorded in inorganic vanadium poisonings. We refer mainly to the effects of vanadate (orthovanadate), vanadyl and pervanadate ions; the main focus is placed on their impact on intracellular signaling. We describe the exact mechanism of the effect of vanadium compounds on protein tyrosine phosphatases (PTP), epidermal growth factor receptor (EGFR), PLCγ...

  1. Thermoelectric properties of fine-grained FeVSb half-Heusler alloys tuned to p-type by substituting vanadium with titanium

    Fine-grained Ti-doped FeVSb half-Heusler alloys were synthesized by combining mechanical alloying and spark plasma sintering and their thermoelectric properties were investigated with an emphasis on the influences of Ti doping and phase purity. It was found that substituting V with Ti can change the electrical transport behavior from n-type to p-type due to one less valence electron of Ti than V, and the sample with nominal composition FeV0.8Ti0.4Sb exhibits the largest Seebeck coefficient and the maximum power factor. By optimizing the sintering temperature and applying annealing treatment, the power factor is significantly improved and the thermal conductivity is reduced simultaneously, resulting in a ZT value of 0.43 at 500 °C, which is relatively high as for p-type half-Heusler alloys containing earth-abundant elements. - Graphical abstract: Fine-grained Ti-doped FeVSb alloys were prepared by the MA-SPS method. The maximum ZT value reaches 0.43 at 500 °C, which is relatively high for p-type half-Heusler alloys. Highlights: ► Ti-doped FeVSb half-Heusler alloys were synthesized by combining MA and SPS. ► Substituting V with Ti changes the electrical behavior from n-type to p-type. ► Thermoelectric properties are improved by optimizing sintering temperature. ► Thermoelectric properties are further improved by applying annealing treatment. ► A high ZT value of 0.43 is obtained at 500 °C for p-type Ti-doped FeVSb alloys.

  2. Effects of cerium and vanadium on the activity and selectivity of MnOx-TiO2 catalyst for low-temperature NH3-SCR

    WU Xiaodong; SI Zhichun; LI Guo; WENG Duan; MA Ziran

    2011-01-01

    MnOx-TiO2, CeO2-MnOx-TiO2 and V2O5-MnOx-TiO2 catalysts for low-temperature NH3-SCR were prepared by sol-gel method.The results showed that both cerium and vanadium prevented the transformation of anatase TiO2 to the rutile phase. The addition of vanadium oxide induced the segregation of crystalline Mn2O3, which contributed little to low-temperature SCR and ammonia oxidation, from the MnOx-TiO2 solid solutions. However, the selectivity of the V-containing catalyst was almost 100% due to the decreased ammonia consumption and enhanced adsorption capacity of ammonia on Brφnsted acid sites at relatively high temperatures. The electron-donating effect of cerium reduced the Mn4+/Mn3+ ratio to some extent, resulting in a decreased activity for ammonia oxidation. This, in combination with the enhanced ammonia adsorption capacity by Cen+ as additional Lewis acid sites, endowed the Ce-doped catalyst a higher N2 selectivity than MnOx-TiO2 despite the slightly elevated light-off temperature for NO conversion.

  3. Influence of the austenite-martensite transformation in the dimensional stability of a new tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.)

    Austenite-martensite transformation influence on the dimensional stability of a new experimental tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.) has been studied. The dimensional stability of this new steel was compared with the dimensional stability of commercial steel, after and before two thermal treatments, T1 (860 degree centigrade) and T2 (900 degree centigrade). The thermal treatments consisted on heating and cooling, at 1 atmosphere of pressure, in N2 atmosphere furnace, following by heating in a conventional furnace at 180 degree centigrade during 1 hour. Initially, the experimental steel composition and Ac1 and Ac3 transformation temperatures were determined by glow-discharge luminescence (GDL) and dilatometric tests, respectively, in order to select the austenization temperatures of T1 and T2 treatments. After hardness measurement, the microstructure of both steels was characterized by X-Ray Diffraction (XRD) and optical metallography, before and after of T1 and T2 thermal treatments. Finally, longitudinal and angular dimensional stability analyses were realized for both commercial and experimental steels. After a contrastive hypothesis analysis, the results showed that the longitudinal relative variation of the experimental steel calculated was around 0.2% and the angular relative variation was not significant. (Author)

  4. Ab initio Investigation of Helium in Vanadium Oxide Nanoclusters

    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.

  5. Effect of drying method on properties of vanadium-molybdenum oxide catalysts

    Effect of drying method of molybdenum and vanadium salt solutions on physicochemical and catalytical properties of vanadium-molybdenum catalysts is studied. It is shown that the drying method of solutions determines the completeness of vanadium binding into oxide vanadium-molybdenum compounds and thus effects the activity and selectivity of catalysts in acrolein oxidation into acrylic acid. Besides the drying method determines the porous structure of catalysts

  6. 9Cr-1Mo martensitic alloys: effects of the nitrogen, niobium and vanadium additions on the microstructure, phase transformations and mechanical properties. Pt. 1 and 2

    9Cr - 1Mo martensitic steels are leading candidate materials for fast reactor sub-assembly wrapper applications. The microstructure, phase transformations and mechanical properties of five 9Cr1Mo alloys containing N, Nb and/or V have been studied by dilatometry, optical and electron transmission microscopy and microanalysis

  7. Effect of minor addition of vanadium on mechanical properties and microstructures of as-extruded near eutectic Al–Si–Mg alloy

    Wu, Yuna; Liao, Hengcheng, E-mail: hengchengliao@seu.edu.cn; Zhou, Kexin

    2014-04-01

    Mechanical properties of near eutectic Al–12.5 wt%Si–0.6 wt%Mg alloys with and without addition of V were tested. Results show that addition of 0.1 wt% V only has a minor influence on the tensile properties of near eutectic Al–Si–Mg alloy in as-cast and as-homogenized conditions. However, it can significantly improve the tensile properties in as-extruded condition. The YS is enhanced nearly 50% and the elongation can reach 14%. Three factors that may contribute to the enhancement of YS were analyzed by EBSD, XRD and TEM investigation, i.e. Δσ{sub gb} (the strengthening from (sub-) grain boundaries), M (Taylor factor) and τ{sub tot} (critical resolved shear stress). Results show that the higher τ{sub tot} in the alloy with V addition is the main contributor to the higher YS. According to the TEM observation and EDX analysis, the fine precipitates contributed to the higher τ{sub tot} in 4{sup #} alloy are quaternary AlFeVSi phases.

  8. Effect of minor addition of vanadium on mechanical properties and microstructures of as-extruded near eutectic Al–Si–Mg alloy

    Mechanical properties of near eutectic Al–12.5 wt%Si–0.6 wt%Mg alloys with and without addition of V were tested. Results show that addition of 0.1 wt% V only has a minor influence on the tensile properties of near eutectic Al–Si–Mg alloy in as-cast and as-homogenized conditions. However, it can significantly improve the tensile properties in as-extruded condition. The YS is enhanced nearly 50% and the elongation can reach 14%. Three factors that may contribute to the enhancement of YS were analyzed by EBSD, XRD and TEM investigation, i.e. Δσgb (the strengthening from (sub-) grain boundaries), M (Taylor factor) and τtot (critical resolved shear stress). Results show that the higher τtot in the alloy with V addition is the main contributor to the higher YS. According to the TEM observation and EDX analysis, the fine precipitates contributed to the higher τtot in 4# alloy are quaternary AlFeVSi phases

  9. Extractable vanadium trihydroxyfluoronates

    Extraction has been studied of vanadium (4) trihydroxyfluoronates into high-molecular-weight alcohols or mixtures of non-polar solvents and monoatomic aliphatic alcohols with a chain containing not less than three carbon atoms. The mechanism of solvation of the complexes extracted has been elucidated. The possibility has been shown of extraction of trihydroxifluoronates of easily hydrolized elements in the systems studied. This can be used for preseparation of vanadium from a number of metals. A procedure has been developed of extraction-spectrophotometric determination of vanadium

  10. Drawing up of a procedure for vanadium determination in mussels using the neutron activation analysis method; Estabelecimento de procedimento para determinacao de vanadio em mexilhoes pelo metodo de analise por ativacao com neutrons

    Seo, Daniele, E-mail: danyseo@uol.com.b [Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil). Centro de Ciencias Biologicas e da Saude; Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vasconcellos, Marina B.A.; Saiki, Mitiko; Catharino, Marilia G.M.; Moreira, Edson G., E-mail: mbvascon@ipen.b, E-mail: mitiko@ipen.b, E-mail: mgcatharino@uol.com.b, E-mail: emoreira@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sousa, Eduinetty C.P.M. de; Pereira, Camilo D.S., E-mail: edvinett@usp.b, E-mail: camilo.pereira@usp.b [Universidade de Sao Paulo (IO/USP), SP (Brazil). Inst. Oceanografico. Lab. de Ecotoxicologia Marinha

    2009-07-01

    This work establishes an adequate procedure for obtaining reliable results for determination of vanadium in mussels, leg by leg by the neutron activation analysis (NAA), viewing the posterior application on the bio monitoring the coastal pollution, particularly near the petroleum terminals.For the evaluation of result quality concerning to the quality of those results, the work analysed the reference material certification NIST SRM 1566b Oyster Tissue. The precision of the results were also analysed using repetitions of mussel samples collected at the coastal of northern Sao Paulo state, Brazil. The NAA procedure consisted of 200 mg of sample and a synthetic standard of vanadium during a period of 8 s and under a thermal neutron flux of 6.6 x 10{sup 12} n cm{sup -2} s{sup -1} at the pneumatic station 4 of the IEA-R1 nuclear reactor of IPEN-CNEN/SP. After a 3 min decay, the measurements of the gamma activities of the sample and the standard were done using a Ge hyper pure semi-conductor detector, connected to gamma ray multichannel analyser. The vanadium were determined by the measurement of the gamma activity of the {sup 52}V through the 1434.08 keV peak, and half-life time of 3.75 min. The concentration of V were calculated by the comparative method. The obtained results indicated the viability of the NAA procedure established for the determination of vanadium in mussels

  11. Vanadium Compounds as Pro-Inflammatory Agents: Effects on Cyclooxygenases

    Jan Korbecki

    2015-06-01

    Full Text Available This paper discusses how the activity and expression of cyclooxygenases are influenced by vanadium compounds at anticancer concentrations and recorded in inorganic vanadium poisonings. We refer mainly to the effects of vanadate (orthovanadate, vanadyl and pervanadate ions; the main focus is placed on their impact on intracellular signaling. We describe the exact mechanism of the effect of vanadium compounds on protein tyrosine phosphatases (PTP, epidermal growth factor receptor (EGFR, PLCγ, Src, mitogen-activated protein kinase (MAPK cascades, transcription factor NF-κB, the effect on the proteolysis of COX-2 and the activity of cPLA2. For a better understanding of these processes, a lot of space is devoted to the transformation of vanadium compounds within the cell and the molecular influence on the direct targets of the discussed vanadium compounds.

  12. Vanadium Compounds as Pro-Inflammatory Agents: Effects on Cyclooxygenases.

    Korbecki, Jan; Baranowska-Bosiacka, Irena; Gutowska, Izabela; Chlubek, Dariusz

    2015-01-01

    This paper discusses how the activity and expression of cyclooxygenases are influenced by vanadium compounds at anticancer concentrations and recorded in inorganic vanadium poisonings. We refer mainly to the effects of vanadate (orthovanadate), vanadyl and pervanadate ions; the main focus is placed on their impact on intracellular signaling. We describe the exact mechanism of the effect of vanadium compounds on protein tyrosine phosphatases (PTP), epidermal growth factor receptor (EGFR), PLCγ, Src, mitogen-activated protein kinase (MAPK) cascades, transcription factor NF-κB, the effect on the proteolysis of COX-2 and the activity of cPLA2. For a better understanding of these processes, a lot of space is devoted to the transformation of vanadium compounds within the cell and the molecular influence on the direct targets of the discussed vanadium compounds. PMID:26053397

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

    Maurer, A.M.; Merritt, K.; Brown, S.A. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Biomedical Engineering)

    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 either 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.

  14. Conceptual chemistry approach towards the support effect in supported vanadium oxides : Valence bond calculations on the ionicity of vanadium catalysts

    Fievez, Tim; De Proft, Frank; Geerlings, Paul; Weckhuysen, Bert M.; Havenith, Remco W. A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide sup

  15. Vanadium research recharged

    US President Barack Obama has described Maria Skyllas-Kazacos’ research as “one of the coolest things I’ve ever said out loud”. Vanadium redox batteries could be electricity’s ultimate storage mechanism.

  16. Hydrogen influence on metal behavior. Pt. 5. Hydrogen embrittlement and stress corrosion cracking of 0,2 wt % vanadium uranium alloy

    Internal hydrogen embrittlement (IHE) has been investigated by means of an improved sensitivity mechanical test involving multiaxial stresses. Embedded disks clamped at their edge are submitted to an increasing gaseous pressure on one side. Modelling with the finite elements methode has demonstrated that the disk pole is plane stressed and the anchorage plane strained. It is shown that thermally H-charged, α-structured, U-0.2V alloy has an IHE threshold lower than 0,02 ppm. A systematic study of the stressing rate influence shows that this alloy is affected by two main kinds of IHE, one due to hydrides at high rates and, one due to dissolved H at low rates. Finally Stress Corrosion Cracking has been studied in aqueous media as a function of pH and the role of HE is indicated. H can form by a chemical reaction with the metal and enter the metal. In pH zones without cracking, H either is not formed or cannot enter the metal. Similar conclusions are proposed for U 0.2 wt%Cr alloy

  17. Nitriding of titanium and titanium: 8 percent aluminum, 1 percent molybdenum, 1 percent vanadium alloy with an ion-beam source

    Gill, A.

    1983-01-01

    Titanium and Ti-8Al-1Mo-1V alloy were nitrided with an ion-beam source of nitrogen or argon and nitrogen at a total pressure of 2 x 10 to the minus 4th power to 10 x 10 to the minus 4th power torr. The treated surface was characterized by surface profilometry, X-ray diffractometry, Auger electron spectroscopy and microhardness measurements. The tetragonal Ti2N phase formed in pure titanium and Ti-8Al-1Mo-1V alloy with traces of AlN in the alloy. Two opposite processes competed during the ion-beam-nitriding process: (1) formation of nitrides in the surface layer and (2) sputtering of the nitrided layers by the ion beam. The highest surface hardnesses, about 500 kg/sq mm in titanium and 800 kg/sq mm in Ti-8Al-1Mo-1V, were obtained by ion nitriding with an ion beam of pure nitrogen at 4.2 x 10 to the minus 4th power torr at a beam voltage of 1000 V.

  18. Electromigration of hydrogen and deuterium in vanadium, niobium and tantalum

    The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium--tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 300C while a steady-state method was used to measure the effective valence

  19. Radiochemical reprocessing of V-Cr-Ti alloy and its feasibility study

    Bartenev, S. A.; Kvasnitskij, I. B.; Kolbasov, B. N.; Romanov, P. V.; Romanovskij, V. N.

    2004-08-01

    An extraction scheme for radiochemical reprocessing of an activated vanadium-chromium-titanium alloy after a fusion reactor decommissioning was developed and checked experimentally. It is based on extraction of V, Cr and Ti freed of activation products from the alloy dissolved in nitric acid. The solution of di-2-ethyl-hexyl-phosphoric acid (D2EHPA) in a hydrocarbon solvent (dodecane) serves as an extractant. It takes 50 extraction steps to recover V, Cr and Ti down to an effective dose rate Technical and economic analysis suggests that the reprocessing alternative is more attractive economically than the burial of spent V-Cr-Ti alloy components.

  20. Effect of aluminum on the equilibrium solubility of hydrogen in vanadium

    A part from the temperature and pressure the solubility of hydrogen in a given matrix is also affected by the composition of the matrix. In metal matrices the presence of one or more substitutional as well as interstitial alloying components can have a significant effect on the solubility of hydrogen. As vanadium is an important refractory metal and vanadium based alloys having high melting point, low solubility of hydrogen isotopes, and most importantly resistance to irradiation properties make it a potential structural material for fusion reactor. It is essential to study the solubility of hydrogen in this metal and its alloys to understand the hydrogen solubility in the service conditions. Vanadium metal, a BCC crystal structure can accommodate more hydrogen in the open voids but solubility of hydrogen substantially affected by the presence of s and p block elements. Aluminothermy reduction of vanadium pentaoxide is one of the method of preparing vanadium metal and therefore aluminium is usually present in unrefined vanadium metal. The alloying effects on the solubility of hydrogen were investigated experimentally in binary V-14%Al (crude),V-10%Al (electron beam melted) and V-5%Al (electron beam melted followed by vacuum arc melting) alloys prepared by aluminothermy followed by refining process mentioned in bracket. It was found that solubility of hydrogen is substantially affected by the presence of aluminum

  1. Vanadium carcinogenic, immunotoxic and neurotoxic effects: a review of in vitro studies.

    Zwolak, Iwona

    2014-01-01

    Deleterious health effects induced by inorganic vanadium compounds are linked with carcinogenic, immunotoxic and neurotoxic insults. The goal of this review is to provide a summary of mammalian cell culture studies (from the 1990s to most recent) looking into the mode of the above-mentioned adverse actions of vanadium. Regarding the carcinogenicity potential, the key cell-based studies have evidenced the ability of vanadium to induce genotoxic lesions, cell morphological transformation and anti-apoptotic effects in a certain type of cells. Two contradictory effects of vanadium on the immune functions of cells have been observed in cell culture studies. The first effect involves reduction of cell immune responses such as vanadium-dependent inhibition of cytokine-inducible functions, which may underlie the mechanism of vanadium-induced immunosuppression. The second one involves stimulation of immune activity, for example, a vanadium-mediated increase in cytokine production, which may contribute to vanadium-related inflammation. So far, an in vitro evaluation of vanadium neurotoxicity has only been reported in few articles. These papers indicate probable cytotoxic mechanisms resulting from exposure of neurons and glial cells to vanadium. In summary, this literature review collects in vitro reports on adverse vanadium effects and thus provides vanadium researchers with a single, concise source of data. PMID:24147425

  2. The precipitation of vanadium compounds

    The results of a study on the chemistry of the precipitation process of vanadium compounds in sulfuric media are presented, in order to recover the vanadium contained in the ore from Campo Alegre de Lourdes (Bahia-Brazil). (Author)

  3. Surface characterization and reactivity of vanadium-tin oxide nanoparticles

    Wang, Chien-Tsung; Chen, Miao-Ting; Lai, De-Lun

    2011-03-01

    Surface state and reactivity of vanadium-tin mixed oxide nanoparticles (V/Sn ratios 0.05-0.2) were characterized by spectroscopic techniques and catalytic measurements. Analyses by X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) revealed that the oxidation state and surface structure of vanadium oxide species and the electronic interaction between Sn and V atoms are dependent upon the vanadium content. These oxides were evaluated as catalysts for methanol oxidation in a fixed-bed reactor. Both reaction rate and formaldehyde selectivity increased with increasing the vanadium amount in catalyst. Results demonstrate that the V 5+ site in the bridging V-O-Sn structure exhibits a high redox activity to facilitate the transformation of adsorbed methoxy to formaldehyde and that the vanadium dispersion plays a crucial role in the surface reactivity. A mechanism that elucidates the catalytic redox process is proposed.

  4. Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, 'Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR, Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T approximate to 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature

  5. Influence of aggressive media on the mechanical behavior of the uranium--0.20 wt % vanadium alloy the role of hydrogen embrittlement

    The tests comprised tensile tests under constant load or up to the fracture point using cylindrical or flat, trapezoidal test pieces, tests in which disks were ruptured under gaseous pressure, and tenacity tests. The alloy was found to be sensitive to: (1) intrinsic brittleness (I.B.) due to dissolved residual hydrogen from the preparation stage. This manifested itself mainly by cracking at an elongation threshold of about 3 percent. (2) Cracking due to stress corrosion (S.C.C.) in the true sense, which is made possible under certain conditions by an imperfect passivation of the metal surface. The process is initiated either by the appearance of microcracks which appear at the surface, or by corrosion pits. (3) Generalized corrosion accelerated by the stress (S.A.C.), whose microscopic appearance is similar to that observed with corrosion under gaseous hydrogen. Below pH 2 there is no stress corrosion. Stress rupture tests in moist air at 80 and 1000C measure I.B. + S.C.C. under high stress, giving rise to short lifetimes. I.B. + S.C.C. + S.A.C., with S.A.C. predominant, occurs under lower stresses that give long lifetimes. Stress rupture tests measure at 20 and 600C I.B. + S.C.C. with I.B. predominant. Under high stresses (short lifetimes) the magnitude of the S.C.C. component increases as the temperature increases. The most serious effects are those of S.A.C. at 80 and 1000C, and of I.B. at all temperatures. The way this alloy behaves can only be changed by an effective reduction in the quantity of residual hydrogen present, or by coatings that will in no case allow the ingress of hydrogen. 62 fig, 82 references, 15 tables

  6. Surface-Activated Amorphous Alloy Fuel Electrodes for Methanol Fuel Cell

    Kawashima, Asahi; Hashimoto, Koji

    1983-01-01

    Amorphous alloy electrodes for electrochemical oxidation of methanol and its derivatives were obtained by the surface activation treatment consisting of electrodeposition of zinc on as-quenched amorphous alloy substrates, heating at 200-300℃ for 30 min, and subsequently leaching of zinc in an alkaline solution. The surface activation treatment provided a new method for the preparation of a large surface area on the amorphous alloys. The best result for oxidation of methanol, sodium formate an...

  7. Vanadium determination in Perna perna mussels (Linnaeus, 1758: Mollusca, Bivalvia) by instrumental neutron activation analysis using the passive biomonitoring in the Santos coast, Brazil

    Vanadium determination present in seawater is of great importance to evaluate marine contamination from industrial sources as well as to identify health hazards since mussels and other marine organisms are used as food. Besides, this evaluation in the Santos coast, SP, Brazil, is important, since this area is impacted by industrial and urban activities and discharges from ships and boats. In a previous study, V results obtained for transplanted mussel (active biomonitoring) were presented. This study aimed the V determination by passive biomonitoring by analyzing Perna perna mussels collected in natural environment, from three sites in Sao Paulo State coast: Cocanha Beach (reference site), Ponta de Itaipu and Palmas Island. Ninety individuals of mussels were collected in each site between September/08 and July/09 during the four seasons of the year. After shell removal and sample preparation, V was determined by instrumental neutron activation analysis. For analytical quality control, the NIST Standard Reference Material SRM 1566b Oyster Tissue was analyzed and the results presented good accuracy. The V concentrations in mussels on dry mass basis varied from 0.77 ± 0.02 to 3.56 ± 0.88 mg kg-1. Statistical tests were applied to the results showing differences on V concentrations among the sampling sites and season of sample collection. (author)

  8. Impaired bacterial attachment to light activated Ni-Ti alloy

    Ni-Ti alloy due to its unique mechanical properties, is used for many types of implants. Failure of these implants can be attributed to many different factors; however infections are a common problem. In this paper, the attachment of the bacteria, Staphylococcus aureus, to the Ni-Ti surface modified by a range of processes with and without of light activation (used to elicit antimicrobial properties of materials) was assessed and related to different surface characteristics. Before the light activation the number of bacterial colony forming units was the greatest for the samples thermally oxidised at 600 deg. C. This sample and the spark oxidised samples showed the highest photocatalytic activity but only the thermally oxidised samples at 600 deg. C showed a significant drop of S. aureus attachment. The findings in this study indicate that light activation and treating samples at 600 deg. C is a promising method for Ni-Ti implant applications with inherent antimicrobial properties. Light activation was shown to be an effective way to trigger photocatalytic reactions on samples covered with relatively thick titanium dioxide via accumulation of photons in the surface and a possible increase in defects which may result in free oxygen. Moreover, light activation caused an increase in the total surface energy.

  9. Impaired bacterial attachment to light activated Ni-Ti alloy

    Chrzanowski, Wojciech; Valappil, Sabeel P. [UCL Eastman Dental Institute, Division of Biomaterials and Tissue Engineering, 256 Gray' s In Road, WC1X 8LD, London (United Kingdom); Dunnill, Charles W. [University College London, Centre for Materials Chemistry, Chemistry Department, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Abou Neel, Ensanya A. [UCL Eastman Dental Institute, Division of Biomaterials and Tissue Engineering, 256 Gray' s In Road, WC1X 8LD, London (United Kingdom); Lee, Kevin [London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Parkin, Ivan P. [University College London, Centre for Materials Chemistry, Chemistry Department, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Wilson, Michael [UCL Eastman Dental Institute, Division of Microbial Diseases, 256 Gray' s In Road, WC1X 8LD, London (United Kingdom); Armitage, David A. [De Montfort University, Leicester School of Pharmacy, The Gateway, Leicester, LE1 9BH (United Kingdom); Knowles, Jonathan C., E-mail: j.knowles@eastman.ucl.ac.uk [UCL Eastman Dental Institute, Division of Biomaterials and Tissue Engineering, 256 Gray' s In Road, WC1X 8LD, London (United Kingdom)

    2010-01-30

    Ni-Ti alloy due to its unique mechanical properties, is used for many types of implants. Failure of these implants can be attributed to many different factors; however infections are a common problem. In this paper, the attachment of the bacteria, Staphylococcus aureus, to the Ni-Ti surface modified by a range of processes with and without of light activation (used to elicit antimicrobial properties of materials) was assessed and related to different surface characteristics. Before the light activation the number of bacterial colony forming units was the greatest for the samples thermally oxidised at 600 deg. C. This sample and the spark oxidised samples showed the highest photocatalytic activity but only the thermally oxidised samples at 600 deg. C showed a significant drop of S. aureus attachment. The findings in this study indicate that light activation and treating samples at 600 deg. C is a promising method for Ni-Ti implant applications with inherent antimicrobial properties. Light activation was shown to be an effective way to trigger photocatalytic reactions on samples covered with relatively thick titanium dioxide via accumulation of photons in the surface and a possible increase in defects which may result in free oxygen. Moreover, light activation caused an increase in the total surface energy.

  10. THE INFLUENCE OF NIOBIUM ON THE ACIDITY AND STRUCTURE OF GAMMA-ALUMINA-SUPPORTED VANADIUM OXIDES

    Sathler M.N.B.

    1998-01-01

    Full Text Available Gamma-alumina-supported niobium oxide was used as a support for vanadium oxides. The influence of the addition of niobium oxide was studied by looking for changes in the structure and acid-base character of superficial species. Vanadium oxide was deposited using the continuous adsorption method; niobium oxide was impregnated using the incipient wetness method. The catalysts were characterized by XPS, UV-visible and IR spectroscopy. Catalytic tests were performed using propane oxidation reaction at 400oC. For coverage below the monolayer, both vanadium and niobium oxides were observed in slightly condensed superficial species. The presence of vanadium oxide on the support was found to increase the Lewis acidity and create some Bronsted acidity. Higher catalytic activity and selectivity for propene were associated with vanadium oxides. The presence of niobium did not contribute to the modification of the chemical properties of superficial vanadium but did decrease the adsorption of vanadium on the alumina.

  11. Lithium-vanadium advanced blanket development. ITER final report on U.S. contribution: Task T219/T220

    The objective of this task is to develop the required data base and demonstrate the performance of a liquid lithium-vanadium advanced blanket design. The task has two main activities related to vanadium structural material and liquid lithium system developments. The vanadium alloy development activity included four subtasks: (1.1) baseline mechanical properties of non irradiated base metal and weld metal joints; (1.2) compatibility with liquid lithium; (1.3) material irradiation tests; and (1.4) development of material manufacturing and joining methods. The lithium blanket technology activity included four subtasks: (2.1) electrical insulation development and testing for liquid metal systems; (2.2) MHD pressure drop and heat transfer study for self-cooled liquid metal systems; (2.3) chemistry of liquid lithium; and (2.4) design, fabrication and testing of ITER relevant size blanket mockups. A summary of the progress and results obtained during the period 1995 and 1996 in each of the subtask areas is presented in this report

  12. Lithium-vanadium advanced blanket development. ITER final report on U.S. contribution: Task T219/T220

    Smith, D.L.; Mattas, R.F. [comps.

    1997-07-01

    The objective of this task is to develop the required data base and demonstrate the performance of a liquid lithium-vanadium advanced blanket design. The task has two main activities related to vanadium structural material and liquid lithium system developments. The vanadium alloy development activity included four subtasks: (1.1) baseline mechanical properties of non irradiated base metal and weld metal joints; (1.2) compatibility with liquid lithium; (1.3) material irradiation tests; and (1.4) development of material manufacturing and joining methods. The lithium blanket technology activity included four subtasks: (2.1) electrical insulation development and testing for liquid metal systems; (2.2) MHD pressure drop and heat transfer study for self-cooled liquid metal systems; (2.3) chemistry of liquid lithium; and (2.4) design, fabrication and testing of ITER relevant size blanket mockups. A summary of the progress and results obtained during the period 1995 and 1996 in each of the subtask areas is presented in this report.

  13. Thermally activated retainer means utilizing shape memory alloy

    Grimaldi, Margaret E. (Inventor); Hartz, Leslie S. (Inventor)

    1993-01-01

    A retainer member suitable for retaining a gap filler placed in gaps between adjacent tile members is presented. One edge of the retainer member may be attached to the gap filler and another edge may be provided with a plurality of tab members which in an intermediate position do not interfere with placement or removal of the gap filler between tile members. The retainer member may be fabricated from a shape memory alloy which when heated to a specified memory temperature will thermally activate the tab members to predetermined memory positions engaging the tile members to retain the gap filler in the gap. This invention has particular application to the thermal tiles on space vehicles such as the Space Shuttle Orbiter.

  14. Measurement of Activity of Indium in Liquid Bi-In-Sn Alloys by EMF Method

    Kumar, M. R.; Mohan, S.; Behera, C. K.

    2016-05-01

    The electrochemical technique based on a molten salt electrolyte galvanic cell has been used to measure the activity of indium in liquid Bi-In-Sn alloys in the temperature range of 723 K to 855 K along three ternary sections. The activity of tin in Bi-Sn binary alloys has also been measured by the same technique in the above temperature range. The activity of indium in Bi-In-Sn alloys shows negative deviation from Raoult's law for most of the compositions and slight positive deviations for a few indium-rich compositions. The ternary excess molar free energies have been calculated by Darken's treatment. Isoactivity curves at 813 K in the ternary Bi-In-Sn alloys were derived by combining the activity data of In-Sn and Bi-In alloys. The values of excess molar free energy obtained in this study are compared with those calculated from the Muggianu model at 813 K.

  15. Nanocrystalline diamond thin films on titanium-6 aluminum-4 vanadium alloy temporomandibular joint prosthesis simulants by microwave plasma chemical vapor deposition

    Fries, Marc Douglas

    A course of research has been performed to assess the suitability of nanocrystal-line diamond (NCD) films on Ti-6Al-4V alloy as wear-resistant coatings in biomedical implant use. A series of temporomandibular (TMJ) joint condyle simulants were polished and acid-passivated as per ASTM F86 standard for surface preparation of implants. A 3-mum-thick coating of NCD film was deposited by microwave plasma chemical vapor deposition (MPCVD) over the hemispherical articulation surfaces of the simulants. Plasma chemistry conditions were measured and monitored by optical emission spectroscopy (OES), using hydrogen as a relative standard. The films consist of diamond grains around 20 nm in diameter embedded in an amorphous carbon matrix, free of any detectable film stress gradient. Hardness averages 65 GPa and modulus measures 600 GPa at a depth of 250 nm into the film surface. A diffuse film/substrate boundary produces a minimal film adhesion toughness (GammaC) of 158 J/m2. The mean RMS roughness is 14.6 +/- 4.2 nm, with an average peak roughness of 82.6 +/- 65.9 nm. Examination of the surface morphology reveals a porous, dendritic surface. Wear testing resulted in two failed condylar coatings out of three tests. No macroscopic delamination was found on any sample, but micron-scale film pieces broke away, exposing the substrate. Electrochemical corrosion testing shows a seven-fold reduction in corrosion rate with the application of an NCD coating as opposed to polished, passivated Ti-6Al-4V, producing a corrosion rate comparable to wrought Co-Cr-Mo. In vivo biocompatibility testing indicates that implanted NCD films did not elicit an immune response in the rabbit model, and osteointegration was apparent for both compact and trabecular bone on both NCD film and bare Ti-6Al-4V. Overall, NCD thin film material is reasonably smooth, biocompatible, and very well adhered. Wear testing indicates that this material is unacceptable for use in demanding TMJ applications without

  16. Amperometric determination of vanadium (3) and vanadium (4) with gallocyanine

    The complexation between vanadium (3), vanadium (4) and gallocyanine in acid solutions has been examined. The apparent stability constants for the complexes have been estimated. The effect of fereign elements on amperometric titration of V(3) and V(4) with gallocyanine has been studied. A method is sUggested of amperometric determination of 0.1-40 mg/ml of vanadium in its lowest oxidation states in the presence of each other

  17. Amperometric determination of vanadium (3) and vanadium (4) with gallocyanine

    Perevoshchikova, V.V. (Gor' kovskij Inzhenerno-Stroitel' nyj Inst. (USSR))

    1983-04-01

    The complexation between vanadium (3), vanadium (4) and gallocyanine in acid solutions has been examined. The apparent stability constants for the complexes have been estimated. The effect of foreign elements on amperometric titration of V(3) and V(4) with gallocyanine has been studied. A method is suggested of amperometric determination of 0.1-40 mg/ml of vanadium in its lowest oxidation states in the presence of each other.

  18. Changes of internal properties of vanadium and structure of its surface under the effect of pulsed high-temperature deuterium plasma

    The work presents experimental research of the influence of a pulse of high-temperature dense plasma on materials, which as are supposed, will be used in future thermonuclear power stations. The experiments were made on 4 kJ Plasma Focus installation. Such type of installations is capable to form pulse of axial plasma flows moving with velocity approximately 108 cm/s and plasma density is about 1018 cm-3. Pure vanadium was chosen in our researches, because it can be used as a basic element at the creation of low-activated alloys. We found that due to a pulse irradiation of vanadium by deuterium plasma, shock waves arises, which result in super-deep penetration of deuterium into a volume of the studied sample. This process is accompanied with the change of vanadium structure, the occurrence of pores in it, and changes of its mechanical properties. The break-away of vanadium particles from the backside surface of the sample and forming of craters were also observed. (author)

  19. Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

    Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

    1998-03-01

    The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

  20. Charpy impact test results for low activation ferritic alloys irradiated to 30 dpa

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-01

    Miniature specimens of six low activation ferritic alloys have been impact field tested following irradiation at 370{degrees}C to 30 dpa. Comparison of the results with those of control specimens and specimens irradiated to 10 dpa indicates that degradation in the impact behavior appears to have saturated by {approx}10 dpa in at least four of these alloys. The 7.5Cr-2W alloy referred to as GA3X appears most promising for further consideration as a candidate structural material in fusion reactor applications, although the 9Cr-1V alloy may also warrant further investigation.

  1. Tensile and impact behaviour of BATMAN II steels, Ti-bearing reduced activation martensitic alloys

    Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.; Pilloni, L.

    Two series of Reduced Activation Ferrous alloys (RAF) have been produced and studied by Casaccia's Laboratories. These martensitic alloys are named BATMAN steels. They are among the few presently developed RAF materials to exploit Ti as a carbide forming and grain size stabilizing element instead of Ta. In this work their mechanical properties are illustrated.

  2. High hardness of alloyed ferrite after nitriding

    Detailed layer-by layer structure and phase analyses of the diffusion layer of nitrided binary alloys of iron with aluminium, chromium, vanadium and titanium have been carried out by means of a complex technique. Transition d-metals (chromium, vanadium and titanium) raise to a greater degree the solubility of nitrogen in the α solid solution, sharply increases the hardness of ferrite and decrease the depth of the layer. Nitrided binary alloys of iron with chromium, vanadium and titanium are strengthened through precipitation from the nitrogen-saturated α-solid solution of nitrides of alloying elements TiN, VN and CrN of a structure B1. A maximum hardness of ferrite alloyed by chromium, vanadium and titanium is observed after nitriding at 550 deg C when the precipitated special nitrides are fully coherent with the α matrix

  3. Slag recycling of irradiated vanadium

    An experimental inductoslag apparatus to recycle irradiated vanadium was fabricated and tested. An experimental electroslag apparatus was also used to test possible slags. The testing was carried out with slag materials that were fabricated along with impurity bearing vanadium samples. Results obtained include computer simulated thermochemical calculations and experimentally determined removal efficiencies of the transmutation impurities. Analyses of the samples before and after testing were carried out to determine if the slag did indeed remove the transmutation impurities from the irradiated vanadium

  4. The association of vanadium with the iron transport system in human blood as determined by gel filtration and neutron activation analysis

    Although vanadium has a suspected physiological role in man, the existing data available on its metabolism at molecular level are very limited and inadequate for modern toxicological and nutritional evaluations. To study its metabolic patterns in the human body it is necessary to determine the association with different biochemical components. The paper describes the identification of V-binding components in human blood by means of fractionation of human serum proteins and neutron activation analysis of the protein fractions of different molecular weight. Since information on the chemical form of V in blood is not well known, preliminary radiotracer experiments were performed by injecting 48V into rats and successively fractionating the 48V plasma proteins by gel filtration, ion-exchange chromatography and poliacrylamide gel electrophoresis. The results indicated that V in rat blood was mainly present in the serum as a V-transferrin biocomplex. It seemed reasonable to assume that a similar biocomplex could also be present in the blood of human subjects. To confirm on man the results obtained by 48V experiments on rats, human plasma proteins were isolated and separated by gel filtration on Sephadex resin and the V content in the elution fractions was determined by neutron activation followed by a rapid radiochemical separation of the induced 52V and gamma-ray spectrometry using a Ge(Li) detector. The results show that V in human plasma was effectively associated with transferrin protein, the iron transport system of the blood. A brief discussion of the results and of the determination of metal-binding components in the human body by combining biochemical techniques and neutron activation analysis is also given (author)

  5. Elemental analysis of brazing alloy samples by neutron activation technique

    Two brazing alloy samples (C P2 and C P3) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 1011 n/cm2/s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 1012 n/cm2/s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab

  6. Carburisation of ferritic Fe-Cr alloys by low carbon activity gases

    Highlights: → Model Fe-Cr alloys are exposed to Ar-CO2 and Ar-CO2-H2O at 650 and 800 deg. C. → Alloy microstructures are extensively modified by carburisation. → Chromium carbides precipitate at both temperatures, and martensite forms at 800 deg. C. → Elevated carbon activities reflect local equilibrium at the scale/alloy interface. - Abstract: Model Fe-Cr alloys were exposed to Ar-CO2-H2O gas mixtures at 650 and 800 deg. C. At equilibrium, these atmospheres are oxidising to the alloys, but decarburising (aC ∼ 10-15 to 10-13). In addition to developing external oxide scales, however, the alloys also carburised. Carbon supersaturation at the scale/alloy interface relative to the gas reflects local equilibrium: a low oxygen potential corresponds to a high pCO/pCO2 ratio, and hence to a high carbon activity. Interfacial carbon activities calculated on the basis of scale-alloy equilibrium are shown to be in good agreement with measured carburisation rates and precipitate volume fractions, providing support for the validity of the thermodynamic model.

  7. Phonon dispersion in vanadium

    Complete text of publication follows. Phonon dispersion curves in Vanadium metal are investigated by neutron inelastic scattering using three-axis spectrometers. Due to extremely low coherent scattering amplitude of neutrons in natural isotope mixture of vanadium the phonon frequencies could be determined in the energy range below about 15 meV. Several phonon groups were measured with the polarised neutron scattering set-up. It is demonstrated that the intensity of coherent inelastic scattering observed in the non-spin-flip channel vanishes in the spin-flip channel. The phonon density of states is measured on a single crystal keeping the momentum transfer equal to a vector of reciprocal lattice where the coherent inelastic scattering is suppressed. Phonon dispersion curves in vanadium, as measured by neutron and earlier by X-ray scattering, are described in frames of a charge-fluctuation model involving monopolar and dipolar degrees of freedom. The model parameters are compared for different transition metals with body-centred cubic-structure. (author)

  8. Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

    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. PMID:25899910

  9. Gas nitriding of high vanadium steels—experiments and simulations

    Larsson, Henrik; Ågren, John

    2004-09-01

    Four experimental high vanadium alloys were gas nitrided in an ammonia-nitrogen atmosphere. The microstructure and concentration gradients have been investigated by means of several techniques. The nitriding process has been tentatively simulated using the DICTRA software. A precise process simulation does not seem possible at present; the reason for this is discussed. Instead, bounds for the carbon and nitrogen concentration profiles were obtained by applying different simulation conditions.

  10. High strength ferritic alloy

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  11. Microstructure of hypereutectic Fe-C-V alloys

    M. Kawalec

    2011-04-01

    Full Text Available The study shows the results of examinations of the microstructure of the in-volume-solidifying Fe-C-V alloys containing carbon in a rangeof 1.53÷3.09% and vanadium in a range of 14.73÷15.71%. All the examined alloys were hypereutectic alloys as proved by the coolingcurves, relevant calculations (Sc and examinations under the microscope. It has been confirmed that the primary carbides of vanadium are crystallising in the form of non-faceted dendrites, acting as a substrate for the growing fibres of vanadium eutectic. The content of primary carbides in the microstructure depends on the content of carbon and vanadium in the alloy. During the conducted research an attempt was also made to determine the content of primary and eutectic carbides and to establish a relationship between carbon and vanadium content in the alloy and the content of primary carbides. In Fe-C-V alloys, besides primary carbides, also a fibrous eutectic composed of ferrite and vanadium carbides of the VC1-x type crystallises.To conduct the previously planned examinations, a series of melts with a variable carbon and vanadium content was carried out underargon atmosphere in a Balzers vacuum furnace. Specimens were examined under an optical microscope, but to investigate in more detailthe geometry of individual phases, they were deep etched with aqua regia and examined by scanning electron microscopy. In theinvestigated alloys, the chemical composition of the crystallised phases was determined by EDS microanalysis.

  12. Low activated materials as plasma facing component

    Low activated materials such as ferritic steel, vanadium alloy and SiC/SiC composite have to be developed for realization of a fusion demonstration reactor. Major issues concerning these low activated materials have been evaluation of neutron irradiation effects and feasibility as blanket materials. Since these are also in-vessel materials, issues of plasma material interactions have to be investigated. Ferritic steel, F82H, is well oxidized in the atmosphere. Thus, pre-baking is necessary before installation. The required baking temperature is higher than 900 K. Vanadium alloy, V-4Cr-4Ti, absorbs hydrogen well and hydrogen embrittlement takes place when the hydrogen concentration exceeds a critical level. In order to avoid hydrogen absorption, the formation of an oxide layer on the alloy was found to be very useful. In JFT-2M, the vanadium alloy was exposed to a deuterium discharge environment for 9 months. On the alloy surface, an oxide deposition layer with a thickness of 200 nm was formed. The deuterium concentration observed was very low, only 1.3 wppm. SiC/SiC composite may be employed as divertor plates in addition to its use as blanket material. Fuel hydrogen retention was very similar to that of graphite but the chemical erosion was negligibly small. (author)

  13. Determination of nickel in finished product alloys by instrumental neutron activation analysis and spectrophotometry

    Nickel contents in different finished product alloys were determined using a k0-based internal monostandard instrumental neutron activation analysis (IM-INAA) method. Five stainless steels (SS) and three high nickel alloys were analyzed by IM-INAA. BCS CRMs 225/1 (low alloy steel) and 466 (austenitic SS) and NIST SRM 247 (high Ni alloy) were analyzed to evaluate the accuracy of the method. The results of CRMs and SS were found to be in good agreement with certified or specified values. The Ni contents in the high nickel alloys were also determined by relative method of NAA for verification. Nickel contents in BCS CRM 466 and SS 316M were determined by UV-Visible spectrophotometry and the values were found to be in good agreement with IM-INAA results. (author)

  14. Study of irradiation creep of vanadium alloys

    Tsai, H.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States)] [and others

    1997-08-01

    Thin-wall tubing was produced from the 832665 (500 kg) heat of V-4 wt.% Cr-4 wt.% Ti to study its irradiation creep behavior. The specimens, in the form of pressurized capsules, were irradiated in Advanced Test Reactor and High Flux Isotope Reactor experiments (ATR-A1 and HFIR RB-12J, respectively). The ATR-A1 irradiation has been completed and specimens from it will soon be available for postirradiation examination. The RB-12J irradiation is not yet complete.

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

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: 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

  16. Ion exchange properties of poly-vanadium and poly-vanadium-molybdenum acids

    Present work is devoted to ion exchange properties of poly-vanadium acid depending on rate of substitution of vanadium on molybdenum. Poly vanadium acid was studied by means of paramagnetic resonance method.

  17. Solvothermal synthesis of Pt-Pd alloys with selective shapes and their enhanced electrocatalytic activities

    Zhang, Zhi-Cheng; Hui, Jun-Feng; Guo, Zhen-Guo; Yu, Qi-Yu; Xu, Biao; Zhang, Xin; Liu, Zhi-Chang; Xu, Chun-Ming; Gao, Jin-Sen; Wang, Xun

    2012-03-01

    Pt-Pd bimetallic alloy nanostructures with highly selective morphologies such as cube, bar, flower, concave cube, and dendrite have been achieved through a facile one-pot solvothermal synthesis. The effects of shape-controllers (sodium dodecyl sulfate (SDS), ethylenediamine-tetraacetic acid disodium salt (EDTA-2Na), NaI) and solvents (water/DMF) on the morphologies were systematically investigated. The electrocatalytic activities of these Pt-Pd alloy nanostructures toward formic acid oxidation were tested. The results indicated that these alloy nanocrystals exhibited enhanced and shape-dependent electrocatalytic activity toward formic acid oxidation compared to commercial Pt black and Pt/C catalysts.Pt-Pd bimetallic alloy nanostructures with highly selective morphologies such as cube, bar, flower, concave cube, and dendrite have been achieved through a facile one-pot solvothermal synthesis. The effects of shape-controllers (sodium dodecyl sulfate (SDS), ethylenediamine-tetraacetic acid disodium salt (EDTA-2Na), NaI) and solvents (water/DMF) on the morphologies were systematically investigated. The electrocatalytic activities of these Pt-Pd alloy nanostructures toward formic acid oxidation were tested. The results indicated that these alloy nanocrystals exhibited enhanced and shape-dependent electrocatalytic activity toward formic acid oxidation compared to commercial Pt black and Pt/C catalysts. Electronic supplementary information (ESI) available: See DOI: 10.1039/c2nr12135b

  18. ⁵¹V NMR Crystallography of Vanadium Chloroperoxidase and Its Directed Evolution P395D/L241V/T343A Mutant: Protonation Environments of the Active Site.

    Gupta, Rupal; Hou, Guangjin; Renirie, Rokus; Wever, Ron; Polenova, Tatyana

    2015-04-29

    Vanadium-dependent haloperoxidases (VHPOs) perform two-electron oxidation of halides using hydrogen peroxide. Their mechanism, including the factors determining the substrate specificity and the pH-dependence of the catalytic rates, is poorly understood. The vanadate cofactor in the active site of VHPOs contains "spectroscopically silent" V(V), which does not change oxidation state during the reaction. We employed an NMR crystallography approach based on (51)V magic angle spinning NMR spectroscopy and Density Functional Theory, to gain insights into the structure and coordination environment of the cofactor in the resting state of vanadium-dependent chloroperoxidases (VCPO). The cofactor environments in the wild-type VCPO and its P395D/L241V/T343A mutant exhibiting 5-100-fold improved catalytic activity are examined at various pH values. Optimal sensitivity attained due to the fast MAS probe technologies enabled the assignment of the location and number of protons on the vanadate as a function of pH. The vanadate cofactor changes its protonation from quadruply protonated at pH 6.3 to triply protonated at pH 7.3 to doubly protonated at pH 8.3. In contrast, in the mutant, the vanadate protonation is the same at pH 5.0 and 8.3, and the cofactor is doubly protonated. This methodology to identify the distinct protonation environments of the cofactor, which are also pH-dependent, could help explain the different reactivities of the wild-type and mutant VCPO and their pH-dependence. This study demonstrates that (51)V-based NMR crystallography can be used to derive the detailed coordination environments of vanadium centers in large biological molecules. PMID:25856001

  19. 炭材料在全钒氧化还原液流电池中的电化学活性%A review of the electrochemical activity of carbon materials in vanadium redox flow batteries

    魏冠杰; 范新庄; 刘建国; 严川伟

    2014-01-01

    Carbon materials mainly act as the electrode in a vanadium redox flow battery (VRFB). Due to the poor electrochemi-cal activity of traditional carbon materials for vanadium redox reactions, a comprehensive study of the electrochemical activity of car-bon materials, especially graphite felt (GF), is greatly needed and has become an important feature of electrode research. This pa-per presents research progress on carbon materials for use in a VRFB, focusing on modifying the GF and new carbons as catalysts for vanadium redox reactions. The electrocatalytic influence of surface oxygen and nitrogen functional groups on vanadium redox reac-tions is introduced. The use of carbon nanotubes and graphene in a VRFB is discussed and future trends to improve the electrochemi-cal activity of carbon materials are highlighted.%炭材料在全钒氧化还原液流电池(钒电池)中主要用作电极。由于传统炭材料对钒电对氧化还原反应的电化学活性较差,因此,对以石墨毡为代表的炭材料电化学活性研究成为钒电池电极研究的重要组成部分。研究从石墨毡电极改性和炭材料作为催化剂应用两方面详述炭材料在钒电池中的电化学活性研究现状,先介绍含氧官能团和含氮官能团对钒电对氧化还原反应的电催化作用,回顾碳纳米管和石墨烯两类新型炭材料在钒电池中的应用。对炭材料电化学活性的今后研究工作进行展望,通过对炭材料性构关系的全面了解和对碳电极上的钒电对电化学反应过程动力学的深入研究,才能为炭材料在钒电池中的实际应用奠定扎实的理论和应用基础。

  20. Vanadium accumulation in carbonaceous rocks: A review of geochemical controls during deposition and diagenesis

    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.

  1. VnfY Is Required for Full Activity of the Vanadium-Containing Dinitrogenase in Azotobacter vinelandii

    Rüttimann-Johnson, Carmen; Rubio, Luis M.; Dean, Dennis R.; Ludden, Paul W.

    2003-01-01

    A gene from Azotobacter vinelandii whose product exhibits primary sequence similarity to the NifY, NafY, NifX, and VnfX family of proteins, and which is required for effective V-dependent diazotrophic growth, was identified. Because this gene is located downstream from vnfK in an arrangement similar to the relative organization of the nifK and nifY genes, it was designated vnfY. A mutant strain having an insertion mutation in vnfY has 10-fold less vnf dinitrogenase activity and exhibits a gre...

  2. Activation analysis application to vanadium concentration in crude oils, in commercial petroleum derivatives, in natural water and in aerosols

    Instrumental neutron activation analysis has been applied to the determination of V concentrations in crude oils, in commercial petroleum derivatives and in aerosols. For 1 min. irradiations in a thermal neutron flux of 1012n.cm-2s-1 and measurements performed with a Ge(Li) well detector, the detection limit is 2x10-3 ppm. The determination of inorganic V concentration in natural water after preconcentration by ions exchangers is obtained with a detection limit equal to 10-4 ppm

  3. Environmentally geochemical characteristics of vanadium in the topsoil in the Panzhihua mining area, Sichuan Province, China

    TENG Yanguo; JIAO Xudong; WANG Jinsheng; XU Wei; YANG Jie

    2009-01-01

    Vanadium is a trace element, which may be biologically beneficial and possibly essential but certainly harmful to human beings and some living organisms if excessive. After over 40 years of development, the mining industry has caused serious environmental problems in the Panzhihua mining area. Vanadium is significantly accu-mulated in the soil of the Panzhihua area. Human activities have intensified the pollution and release of vanadium and caused serious damages to the ecological system there. In the past few years, the authors have made investiga-tions into and assessments on the geochemical distribution, chemical speciation, adsorption characteristics and transfer behavior of vanadium in the topsoil in the Panzhihua mining area. The results showed that: (1) the difference in the contents of vanadium in soil between premonsoon and monsoon is insignificant; (2) the adsorption isotherms of vanadium on soil in the Panzhihua mining area ate well described by the Langmuir type; (3) the transfer ability of vanadium in soil is interrelated to soil properties; and (4) the chemical speciation of vanadium shows an order of insoluble residue > oxidizable=reducible > soluble component. According to the above results, some countermea-sures to control pollution of vanadium in soil should be put forward.

  4. Characterization of Vanadium Flow Battery

    Bindner, Henrik W.; Krog Ekman, Claus; Gehrke, Oliver; Isleifsson, Fridrik Rafn

    2010-01-01

    This report summarizes the work done at Risø-DTU testing a vanadium flow battery as part of the project “Characterisation of Vanadium Batteries” (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risø DTU. A test programme has been carried out to get hands-on experience with the technology, to charac...

  5. Determination of vanadium by instrumental neutron activation analysis using a high counting-rate γ-ray spectrometer

    In instrumental neutron activation analysis (INAA), high performance gamma ray spectrometry is indispensable for calculating the analysis values of good accuracy. In this research, as the measuring method at high rate of count, the gamma ray spectrometry by using the pulse pile-up rejector (PUR) which can remove pulse pile-up with the instrument was investigated. Moreover, in order to compensate the radioactivity attenuation at the time of the measurement at high rate of count, the function that the rate of dead time every 1 s in the measurement can be recorded was added to a gamma ray spectrometer. The performance of this spectrometer and the quantification of V in living body samples, that are mussels and tea leaves are reported. (K.I.)

  6. Effect of activity differences on hydrogen migration in dissimilar titanium alloy welds

    The effect of alloy composition on hydrogen activity was measured for seven titanium alloys as a means to determine the tendency for hydrogen migration within dissimilar metal welds. The alloys were: Ti-CP (unalloyed Ti), Ti-3Al-2.5V, Ti-3Al-2.5V-3Zr, Ti-3Al-2Nb-1Ta, Ti-6Al, Ti-6Al-4V, and Ti-6Al-2Nb-1Ta-0.8Mo. Hydrogen pressure-hydrogen concentration relationships were determined for temperatures from 600 C to 800 C and hydrogen concentrations up to approximately 3.5 at. pct (750 wppm). Fusion welds were made between Ti-CP and Ti-CP and between Ti-CP and Ti-6Al-4V to observe directly the hydrogen redistribution in similar and dissimilar metal couples. Hydrogen activity was found to be significantly affected by alloying elements, particularly Al in solid solution. At a constant Al content and temperature, an increase in the volume fraction of β reduced the activity of hydrogen in α-β alloys. Activity was also found to be strongly affected by temperature. The effect of temperature differences on hydrogen activity was much greater than the effects resulting from alloy composition differences at a given temperature. Thus, hydrogen redistribution should be expected within similar metal couples subjected to extreme temperature gradients, such as those peculiar to fusion welding. Significant hydrogen redistribution in dissimilar alloy weldments also can be expected for many of the compositions in this study. Hydride formation stemming from these driving forces was observed in the dissimilar couple fusion welds. In addition, a basis for estimating hydrogen migration in titanium welds, based on hydrogen activity data, is described

  7. Novel catalytic effects of Mn3O4 for all vanadium redox flow batteries.

    Kim, Ki Jae; Park, Min-Sik; Kim, Jae-Hun; Hwang, Uk; Lee, Nam Jin; Jeong, Goojin; Kim, Young-Jun

    2012-06-01

    A new approach for enhancing the electrochemical performance of carbon felt electrodes by employing non-precious metal oxides is designed. The outstanding electro-catalytic activity and mechanical stability of Mn(3)O(4) are advantageous in facilitating the redox reaction of vanadium ions, leading to efficient operation of a vanadium redox flow battery. PMID:22540132

  8. PWSCC Preventive Maintenance Activities for Alloy 600 in Japanese PWR Plants

    Because many nuclear plants have been in operation for ages, the importance of preventive maintenance technologies is getting higher. One conspicuous problem found in pressurized water reactor (PWR) plants is the primary water stress corrosion cracking (PWSCC) observed in Alloy 600 (a kind of high nickel based alloy) parts. Alloy 600 was used for butt welds between low alloy steel and stainless steel of nozzles of Reactor Vessel (RV), Steam Generator (SG), and Pressurizer (Pz). As PWSCC occurred at these parts may cause Loss of Coolant Accident (LOCA), preventive maintenance is necessary. PWSCC is considered to be caused by a mixture of three elements: high residual tensile stress on surface, material (Alloy 600) and environment. PWSCC can be prevented by improving one of the elements. MHI has been developing stress improvement methods, for example, Water Jet Peening (WJP), Shot Peening by Ultrasonic vibration (USP), and Laser Stress Improvement Process (L-SIP). According to the situation, appropriate method is applied for each part. WJP has been applied for RV nozzles of a lot of plants in Japan. However PWSCC was observed in RV nozzles during the inspection before WJP in recent years, MHI developed the Advanced INLAY system to improve the material from Alloy 600 to Alloy 690. Alloy 600 on the inner surface of the nozzles is removed and welding with Alloy 690 is performed. In addition, heat treatments for the nozzles are difficult for its structural situation, so ambient temperature temper bead welding technique for RV nozzles was developed to make the heat treatments unnecessary. This paper describes countermeasures against PWSCC and introduces the maintenance activities performed in Japan. (author)

  9. Researches on vanadium and its compounds

    In this research thesis, the author proposes a new study of the action of some reduction agents on two groups of vanadium compounds, oxides and chlorides. Thus, he reports the study of the circumstances of reduction of vanadium oxides by carbon and of vanadium carburization from these compounds. He also reports the determination of the composition of vanadium melts obtained at high temperatures (either in a vacuum furnace or with an electric arc furnace). In order to determine in which conditions the processing of vanadium oxides could produce the pure metal, the author studied the action of calcium and magnesium on the vanadium pentoxide and trioxide. The second part of the thesis addresses the preparation of pure vanadium from vanadium anhydride chlorides. Then, the author reports the development of processes which could easily produce powdered vanadium

  10. Activity measurement of solid Cu-In alloys by EMF method with solid electrolyte

    Katayama I.

    2002-01-01

    Full Text Available The thermodynamic activity of indium in the solid Cu-In alloys was obtained from the EMF measurement of cell: In,In2O3, ZrO2(+11mol%CaO, Cu-In,In2O3 for 16 alloys in the temperature range 773 to 900K. Activity changes with composition at 823K are very large in the and - phase regions. Activity and free energies of formation are derived and compared with the published data.

  11. Determination of vanadium, manganese and tungsten in steels with an 241 Am-Be isotopic neutron source

    A non-destructive neutron activation method was developed for determination of vanadium, manganese, and tungsten in alloy-steel, with the aid of an Am-Be 1,85x1011Bq(5Ci) isotopic neutron source, employing NaI (T1) detector well type 2x2 in. The 51V (n,γ) 52V, 55Mn (n,γ) 56Mn, and 186W (n,γ) 187W nuclear reactions are induced in steel samples subject to activation by thermal neutron. After irradiation, the activity of the samples was measured by γ-spectrometry under the 1434 KeV 52V, 847KeV 56Mn, and 686 KeV 187W photopeaks. Possible interferences due to other radionuclides activity were investigated by determining the 52V, 56Mn, and 187W half-lifes. The time of analysis for vanadium determination was 11 min, with 1,5% of precision and 3,4% of average absolute deviation. The time of analysis for manganese determination was 22,8 min with 4,0% of precision and 3,4% of average absolute deviation. The time of analysis for tungsten determination was 44,62 min with 3,8% of precision and 3,1% of average absolute deviation. The activation analysis method is adequated for steel quality control in industry. (Author)

  12. Discovery of the Vanadium Isotopes

    SHORE, A.; A. Fritsch; Heim, M.; Schuh, A.; Thoennessen, M

    2009-01-01

    Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Vanadium effect on ductility of nickelless ferrite stainless steels

    Examined were the structure, properties, and the process characteristics of a new 08Kh18F2T1 nickel-free stainless steel, which differs from 08Kh18T1 steel by the additional alloying with vanadium in an amount of up to 1.5%. It has been established that the elongation of the specimens made of 0Kh18F2T1 steel increases noticeably (on the average of 7%) with a certain increase in its strength, as compared with the elongation of 0.8Kh18T1 steel. By varying the modes of the thermal treatment of cold-rolled sheet, the mechanical strength of 0318F2T1 steel may be increased up to 53 to 55.5 kgf/mm2, while the elongation of the steel is preserved within the range of 39 to 41%. It is shown that the additional alloying with vanadium completely suppresses α reversible γ transformation, and cleans the boundaries of ferrite grain. This is substantiated by the measurement of the microhardness at the grain boundaries. Stabilization of ferrite occurs owing to the binding of carbon into titanium carbides and to the introduction of vanadium into the solid solution, and it considerably reduces the absolute and the relative difference between the central portion and the boundaries of grains

  14. Low activation R-tokamak with aluminum alloy

    An aluminum alloy system is considered as an alternative of the first phase design of the R-tokamak. The 1-D calculation showed that the radiation level outside the vacuum vessel could be reduced by a factor of 30 about half a month after a D-T shot, when the aluminum alloy system is adopted instead of a stainless steel system. The aluminum system has weak mechanical strength, is highly conductive, and shows overaging effect at a certain low temperature. Accordingly, it is necessary to overcome these points. The highly conductive aluminum case leads to considerable increase in power consumption. Various problems on the toroidal coils, the vacuum system, and the limiter were studied. The optimization of the device parameters was investigated. (Kato, T.)

  15. Development of vanadium fuel cladding for Sodium Fast Reactors

    Vanadium alloys are promising material for some core components of the Sodium Fast Reactors, especially for fuel cladding applications. With good mechanical properties up to 800°C at least, good behavior under irradiation above 400°C and limited swelling, they also have the benefit from fusion program. In 2010, CEA launched the manufacturing of a V-4Cr-4Ti alloy, well documented in literature, to validate the uneasy fabrication process linked to interstitial element sensitivity and potential pollution in master alloys. 30kg of CEA-J57 alloy (7 mm-plates) were fabricated for the CEA by GfE Metalle und Materialien GmbH, Nuremberg, Germany. The program includes the investigation of recrystallization, resulting microstructure and DBTT values, high temperature mechanical properties such as tensile strength and creep resistance, chemical compatibility with both the oxide fuel and the coolant and assessment of tube fabrication, actually a triplex tube with inner and outer liners to protect vanadium from oxidation during the hot processing. (author)

  16. Charpy impact test results of four low activation ferritic alloys irradiated at 370 degrees C to 15 DPA

    Miniature CVN specimens of four low activation ferritic alloys have been impact tested following irradiation at 370 degrees C to 15 dpa. Comparison of the results with those of control specimens indicates that degradation in the impact behavior occurs in each of these four alloys. The 9Cr-2W alloy referred to as GA3X and the similar alloy F82H with 7.8Cr-2W appear most promising for further consideration as candidate structural materials in fusion energy system applications. These two alloys exhibit a small DBTT shift to higher temperatures but show increased absorbed energy on the upper shelf

  17. Charpy impact test results of four low activation ferritic alloys irradiated at 370{degrees}C to 15 DPA

    Schubert, L.E.; Hamilton, M.L.; Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    Miniature CVN specimens of four low activation ferritic alloys have been impact tested following irradiation at 370{degrees}C to 15 dpa. Comparison of the results with those of control specimens indicates that degradation in the impact behavior occurs in each of these four alloys. The 9Cr-2W alloy referred to as GA3X and the similar alloy F82H with 7.8Cr-2W appear most promising for further consideration as candidate structural materials in fusion energy system applications. These two alloys exhibit a small DBTT shift to higher temperatures but show increased absorbed energy on the upper shelf.

  18. Measurement of zinc activity in the ternary In–Zn–Sn alloys by EMF method

    Behera, C.K., E-mail: ckbehera.met@itbhu.ac.in; Sonaye, A.

    2013-09-20

    Highlights: • Activity of zinc in the ternary In–Zn–Sn system has been measured in the temperature range 753–853 K by EMF method. • Isoactivity lines for zinc reflect the positive deviation from the ideality at 813 K. • The activity of indium in In–Sn binary system shows negative deviation from Raoult's law over entire range of composition. • Ternary excess molar free energies at 813 K are computed by Darken's treatment. • Calculated molar excess free energies for the ternary systems are compared with the Chou's theoretical model data. - Abstract: Activity of zinc in liquid In–Zn–Sn alloys has been measured by electrochemical technique based on molten salt electrolyte galvanic cell in the temperature range 753–853 K along three ternary sections of Zn{sub x}(In{sub y}Sn{sub 1−y}){sub 1−x} where y = 0.67, 0.50 and 0.33. The activity of indium in In–Sn binary alloys has also been measured by the same technique in the same temperature range. The activity of Zinc in In–Zn–Sn alloys shows positive deviation from the Raoult's law over entire range of composition. The activity of indium in In–Sn alloys shows negative deviations from ideality for entire composition. The excess molar free energies have been computed by the Darken's treatment of the ternary solutions using In–Sn binary data and ternary data in this study. Isoactivity curves at 813 K in the ternary In–Zn–Sn alloys were derived by combining the activity data of In–Zn and Sn–Zn alloys. The values of excess molar free energy in this study are in good agreement with those calculated from the general model calculation proposed by Chou.

  19. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    Vej-Hansen, Ulrik Grønbjerg

    essential for wide-spread use of this technology. platinum alloys have shown great promise as more active catalysts, which are still stable under reaction conditions. We have investigated these systems on multiple scales, using either Density Functional Theory (DFT) or Effective Medium Theory (EMT......In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts are...... increased activity that has been seen experimentally. We show how the platinum-platinum distance at the surface is decreased for a variety of alloy phases in the core, with greater compression of the overlayer for core phases with lattice parameters which are either much smaller or much larger than pure...

  20. 活化条件对钒磷氧催化剂物性及反应性能的影响%Influence of Activation Conditions on Physical Properties and Reaction Performance of Vanadium-Phosphorous Oxide Catalyst

    许磊; 佟明友; 王海波

    2011-01-01

    对钒磷氧催化剂前驱体进行活化,通过正交试验确定了适宜的活化条件,并对催化剂进行了BET、XRD、XPS等表征.结果表明,影响顺酐收率的各因素主次顺序为:活化气氛>活化时间、升温速率,适宜的活化条件为,水蒸气/空气比25%/75%,活化时间8h,升温速率5℃/min.此条件下活化的催化剂,比表面积达到37.098 m2/g,晶相结构较好,钒的平均氧化值是4.26,而顺酐的摩尔收率也达到65.12%.%Vanadium-phosphorous oxide catalyst precursors were activated and suitable activation conditions were found by orthogonal experiment. BET,XRD and XPS techniques were used to characterize the catalyst. The results show that the order of various factors to influence maleic anhydride yield is activation atmosphere>activation time> temperature increasing rate. Suitable activation conditions are as follows: ratio of steam to air 25%/75%,activation time 8 h,temperature increasing rate 5℃/min. After the catalyst is activated under above conditions, its surface area is up to 37.098 m2/g, its crystal structure is better and its average vanadium oxidation state is 4.26, the yield of maleic anhydride is up to 65.12%.

  1. Core-Shell Vanadium Modified Titania@β-In2S3 Hybrid Nanorod Arrays for Superior Interface Stability and Photochemical Activity.

    Mumtaz, Asad; Mohamed, Norani Muti; Mazhar, Muhammad; Ehsan, Muhammad Ali; Mohamed Saheed, Mohamed Shuaib

    2016-04-13

    Core-shell rutile TiO2@β-In2S3 and modified V-TiO2@β-In2S3 were synthesized to develop bilayer systems to uphold charge transport via an effective and stable interface. Morphological studies revealed that β-In2S3 was deposited homogeneously on V-TiO2 as compared to unmodified TiO2 nanorod arrays. X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrometry studies verified the presence of various oxidation states of vanadium in rutile TiO2 and the vanadium surface was utilized for broadening the charge collection centers in host substrate layer and hole quencher window. Subsequently, X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectra confirmed the rutile phases of TiO2 and modified V-TiO2 along with the phases of crystalline β-In2S3. XPS valence band study explored the interaction of valence band quazi Fermi levels of β-In2S3 with the conduction band quazi Fermi levels of modified V-TiO2 for enhanced charge collection at the interface. Photoelectrochemical studies show that the photocurrent density of V-TiO2@β-In2S3 is 1.42 mA/cm(2) (1.5AM illumination). Also, the frequency window for TiO2 was broadened by the vanadium modification in rutile TiO2 nanorod arrays, and the lifetime of the charge carrier and stability of the interface in V-TiO2@β-In2S3 were enhanced compared to the unmodified TiO2@β-In2S3. These findings highlight the significance of modifications in host substrates and interfaces, which have profound implications on interphase stability, photocatalysis and solar-fuel-based devices. PMID:26852779

  2. Electrocatalytic activity of Rh-Ru alloys in electroreduction process

    The authors study the kinetics of cathodic hydrogen evolution in 1 N H2SO4 and of maleic acid electroreduction in C4H4O4 solutions of different concentrations in 1 N H2SO4 as a base electrolyte at Rh-Ru alloy ingots prepared by vacuum arc melting. The results of polarization measurements for cathodic hydrogen evolution were analyzed in semilogarithmic plots of overvoltage against the logarithm of current density. Over the range of current densities from 10-5 to 10-3 A/cm2, the polarization curves exhibit distinctly linear sections and can be described by the Tafel equation

  3. DEVELOPMENT OF OXIDATION RESISTANT TITANIUM ALLOYS BY NIOBIUM ADDITION

    Ackland, Graeme; Siemers, Carsten; Tegner, Bengt E.; Saksl, K.; Brunke, F.; Kohnke, M,

    2014-01-01

    The application of titanium alloys is limited to 550°C due to their poor oxidation resistance. It is known that the addition of niobium improves the oxidation resistance of titanium whereas elements like vanadium do not support titanium’s oxidation behaviour. Hence, the underlying mechanisms are not understood. In the present study, different binary titanium-niobium and titanium-vanadium alloys as well as commercially pure titanium were investigated. Oxidation experiments were carried out at ...

  4. Determination of trace impurities of chlorine in zirconium-alloy matrices using neutron activation technique

    Naik, H.; Nathaniel, T. Newton [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiochemistry Div.; Sant, V.L. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Fuel Chemistry Div.; Suryanarayana, S.V. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Nuclear Physics Div.; Prajapati, P.M. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Physics Design Div.

    2011-07-01

    Trace impurities of chlorine in the zircaloy-2 and Zr-2.5% Nb alloy matrix have been determined using neutron activation analysis (NAA) and off-line {gamma}-ray spectrometric technique. The results have been compared with the values obtained from pyrohydrolysis-IC and spark source mass spectrometric method. The limit of internal precision error from the neutron activation technique is 6.7% for zircaloy-2 and 9% for Zr-2.5% Nb alloy, which are lower than that of pyrohydrolysis-IC and spark source mass spectrometric measurements respectively. For both alloys the results from present work based on NAA technique are slightly higher than the results based on the other two methods but are comparable within the uncertainty. Read More: http://www.oldenbourg-link.com/doi/abs/10.1524/ract.2011.1863 (orig.)

  5. On some properties of vanadium-, chromium- and manganese compounds under floatation

    Properties of compounds, formed by vanadium-, chromium- and manganese anions with quaternary ammonium bases (QAB) during their flotation separation from aqueous solutions are studied. Compounds of alcylbenzyldimethylammoniumchloride and alcyltrimethylammoniumchloride are used as surfactants. Optimum pH values in the case of vanadium flotation equal 25 to 5.5. Negatively charged vanadium polyanions interact with positively charged QAB hydrocarbon radical thus forming hydrophobic precipitates which are easil floated. Thermogravimetric analysis of the precipitate destruction process at heating has been used to show, that in the vanadium-containing compound the first stage of decomposition (low temperature) is less power-consuming, than the second one (high temperature). Vanadium containing precipitate decomposes with the formation of a metal phase. The supposition is made on the kinetics of chemical interaction between metal polyanions and cation-active collectors

  6. Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

    陈卫祥; 成旦红; 刘淑兰; 郭鹤桐

    2002-01-01

    Ni-La alloy coating was prepared by electrodeposition.The effect of cathodic current density on the La content of the alloy coatings was discussed.It is found that the content of La in the alloy increases with increasing the cathodic current density.The microstructures and codeposition mechanism of Ni-La alloy coatings were investigated by means of X-ray diffraction (XRD) and cyclic voltammetry (CV).The results demonstrate that the Ni-La alloy is FCC and codeposited by the induced mechanism.The hydrogen evolution reaction (HER) on the electrodeposited Ni-La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves.It is found that La-Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode,and that the exchange current density increases with increasing the La content of alloys.The good electrocatalytic activity for HER of this Ni-La alloy is attributed to the synergism of the electronic structure of La and Ni.The electrodeposited La-Ni alloys have a certain electrochemical hydrogen storage capacity of 34~143 mAh/g,which increases with increasing the La content of alloys.

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

    Sepehr, Fatemeh; Paddison, Stephen J

    2015-06-01

    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. PMID:25954916

  8. Protective effects of Sesamum indicum extract against oxidative stress induced by vanadium on isolated rat hepatocytes.

    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. PMID:25727928

  9. Fracture mechanics of pseudoelastic NiTi alloys: review of the research activities carried out at University of Calabria

    E. Sgambitterra

    2013-01-01

    Full Text Available This paper reports a brief review of the research activities on fracture mechanics of nickel-titanium based shape memory alloys carried out at University of Calabria. In fact, this class of metallic alloys show a unusual fracture response due to the reversible stress-induced and thermally phase transition mechanisms occurring in the crack tip region as a consequence of the highly localized stresses. The paper illustrates the main results concerning numerical, analytical and experimental research activities carried out by using commercial NiTi based pseudoelastic alloys. Furthermore, the effect of several thermo-mechanical loading conditions on the fracture properties of NiTi alloys are illustrated.

  10. Titanium and titanium alloy forgings

    The specification covers nine grades of annealed titanium and titanium alloy forgings as follows: Grade F-1, F-2, F-3, and F-4 unalloyed titanium; Grade F-5 titanium alloy (6% aluminum, 4% vanadium); Grade F-6 titanium alloy (5% aluminum, 2.5% tin); Grade F-7 and F-11 unalloyed titanium plus palladium; Grade F-12 titanium alloy (0.3% molybdenum, 0.8% nickel). The specification includes ordering information, manufacture, chemical requirements, mechanical requirements, nondestructive tests, dimensions and permissible variations, finish, certification, packaging, and marking

  11. EFFECT OF VANADIUM ON THE DEACTIVATION OF FCC CATALYSTS

    Roncolatto R.E

    1998-01-01

    Full Text Available This work provides concrete evidence that vanadium causes the destruction of the zeolite in the FCC catalysts by a mechanism of acid attack or solid-solid transformation, as well as additional dealumination of the zeolite framework in the presence of steam and at high temperature. While these effects resulted in the reduction in crystallinity (zeolite Y content, specific area and unit cell size of the Y zeolite as the amount of vanadium in the catalysts increased, the reduction in activity was the most pronounced. The differences in these behaviors were interpreted and the model can be used for better catalyst formulation or screening.

  12. FIA versatile system for spectrophotometric determinations of vanadium and molybdenum exploring the catalytic activities of V(V) and Mo(VI); Sistema FIA polivalente para determinacoes espectrofotometricas de vanadio e molibdenio explorando as atividades cataliticas de V(V) e Mo(VI)

    Luca, Gilmara Caseri de

    1996-02-01

    A versatile system for chemical analysis by flow injection analysis was developed and applied for catalytic spectrophotometric determination of vanadium or molybdenum in metallic alloys. The selected methods were based upon indicator reactions chromotropic (CS)-bromate acid or hydrogen iodide-peroxide, respectively. Initially, a model system was proposed, in which common parameters for methods were studied. This included a re-sampling process in which high degrees of samples dilution were obtained. Other parameters such as concentrations and reagents addition order, reaction medium Ph, temperature and ionic power, as well as procedures for sample solubilization, were studied relating to each method. A mini-column with cationic exchanger resin (Dowex 50W-X8, 50-100 mesh, H{sup +} form) was used. The system for vanadium determination processes 120 samples by hour, consuming 2,0 mg CS and 10 mg K Br O{sub 3b}y determination. Concerning the method for molybdenum, the reagents consumption was 2,0 mg KI and 1,0 {mu}L of solution 30% H{sub 2}O{sub 2} by determination, since the analytic velocity was the same, in relation to vanadium.

  13. Process development for economical processing of various vanadium-bearing raw materials

    Three different vanadium-containing byproducts were investigated, with the object of extracting the vanadium economically. Leach residues are formed in the known treatment of vanadium-containing blast furnace slags. It was found possible, by means of reduction with carbon in an electric arc furnace, to carry over 73,5% of the input vanadium into the metal alloy which in addition to 67% Fe and 2% V also contains 7% Cr and 5,5% C. Vanadium-containing fly ash results from the combustion of crude oil. This contains 0,5 to 6 % V. Tests on several processes, such as oxidising roast with subsequent leaching, reducing roast with subsequent leaching with sulphuric acid, and alkali soda roasting, gave widely varying results on the fly ash derived from various sources. The most suitable method must be worked out individually for each material. Vanadium-containing waste salt results from the recovery of aluminium from bauxites. It contains an average of about 4% V and 5% P, as well as 0,5% As. Dissolution of the waste salt in water with the addition of sulphuric acid results in a solution containing 20 g/1 V, from which, after removal of the phosphorus, ammonium polyvanadate can be precipitated by known means. In addition to the recovery of the vanadium the object is also to obtain a saleable phosphorus-containing product. After dissolution and neutralisation of the waste salt, it is possible to obtain with phosphoric acid a secondary sodium phosphate which, however, even after recrystallisation, does not satisfy the purity requirements of the detergent industry. The sodium sulphate/phosphate resulting from the neutralisation with sulphuric acid cannot be used by the phosphate industry, although the secondary sodium phosphate can be so used. A calculation shows however that with this the vanadium recovery is no longer economic

  14. Dislocation Climb Sources Activated by 1 MeV Electron Irradiation of Copper-Nickel Alloys

    Barlow, P.; Leffers, Torben

    1977-01-01

    irradiation temperatures corresponding to the highest source densities is approximately 350°–500°C. The climb sources are not related to any pre-existing dislocations resolved in the microscope. The sources emit three types of loop: ‘rectangular’ loops with a100 Burgers vector and {100} habit plane, normal...... prismatic loops with Burgers vector a/2110, and Frank loops. There is no significant difference between the apparent activation energy for growth of the three types of loops. The source points are suggested to be submicroscopic nickel precipitates-with reference to the existing evidence that......Climb sources emitting dislocation loops are observed in Cu-Ni alloys during irradiation with 1 MeV electrons in a high voltage electron microscope. High source densities are found in alloys containing 5, 10 and 20% Ni, but sources are also observed in alloys containing 1 and 2% Ni. The range of...

  15. Role of vanadium in Keggin heteropoly molybdate supported on titania catalysts for oxidation reactions

    A Srivani; K T Venkateswara Rao; P S Sai Prasad; N Lingaiah

    2014-03-01

    Vanadium-incorporated molybdophosporic acid catalysts supported on titania were prepared and characterized by FT-IR, X-ray diffraction and laser Raman spectroscopy. Characterization data reveals the incorporation of vanadium into the primary structure of Keggin ion of MPA. Catalysts activities were evaluated for oxidation of 1,2-benzenedimethanol using H2O2 and O2 as oxidants. Vanadium-containing catalysts showed high activity compared to their parent heteropoly acids. Oxidation ability depended on the number of V atoms present in Keggin heteropoly molybdate. Effect of reaction parameters on the oxidation ability was also evaluated.

  16. Annealing of neutron-irradiated vanadium containing oxygen

    A study to clarify the role of interstitial oxygen in irradiated vanadium by measuring the activation energy of the 0.2 T/sub m/ recovery stage in well-characterized samples, where T/sub m/ is the melting temperature in degrees Kelvin, is described

  17. Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum

    The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium-tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 300C while a steady-state method was used to measure the effective valence. The use of mass spectrographic techniques on a single specimen which contained both hydrogen and deuterium greatly increased the precision with which the isotope effect in the effective valence could be measured

  18. Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal

    Hu, Yang-jia; Zhang, Yi-min; Bao, Shen-xu; Liu, Tao

    2012-10-01

    The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.

  19. Vanadium removal from petroleum refinery wastewater

    Nurdogan, Y. [Bechtel National, Inc., San Francisco, CA (United States); Meyer, C.L. [Shell Development Co., Houston, TX (United States)

    1996-11-01

    Although a numerical effluent limit has not been proposed for vanadium, San Francisco Bay Area refineries have been investigating reasonable source control and treatment measures to limit the discharge of vanadium as part of their National Pollution Discharge Elimination System (NPDES) permit requirements because vanadium may contribute to aquatic toxicity. The NPDES permit issued for the Shell Martinez Manufacturing Complex (MMC) by the Regional Water Quality Control Board (CRWQCB) required that in the investigation of control strategies for vanadium, consideration must be given to source control measures that would reduce the discharge to the extent practicable. This paper summarizes the results of bench- and pilot-scale studies to remove vanadium from process effluent of the Shell MMC. This study has resulted in the following conclusions: vanadium in the Shell MMC refinery wastewater is generated by two major sources--the Flexicoker and Stretford processes; ferric and ferrous salts are both effective in removing vanadium from wastewaters; there are tradeoffs between the initial vanadium concentration, the final pH, and the final dissolved vanadium concentration, for both ferrous and ferric reagents; recycle of iron hydroxide sludge can reduce the amount of reagent needed to attain a given vanadium concentration; other things being equal, less ferric than ferrous reagent is required to produce the same removal of vanadium; the dewatered sludge from the pilot plant was tested for its hazardous waste characteristics; a high pH sludge regeneration and reuse process appears to be a promising method of cleaning up the hazardous iron sludge.

  20. Corrosion of vanadium and V 3Ti 1Si in flowing lithium

    A pumped Li loop fabricated from a titanium stabilized Type 316 steel was designed and constructed. At temperatures of about 823 K, experiments over a duration of more than 7500 h were performed. A magnetic trap had to be incorporated just before the flowmeter to avoid the precipitation of magnetic particles. Therefore it was possible to investigate the influence of the magnetic trap on the corrosion behaviour of V in flowing Li. The results are as follows: - The corrosion rate of V is about 14 μm/year and independent of the nitrogen content of Li. The corrosion rate of V 3Ti 1Si depends on the N concentration of Li. At about 30 wppm N in Li a vanadium-titanium-nitride is formed at the surface of the specimens. Hence, a low rate of 4 μm/year can be stated. - Both materials pick-up more N than C from Li, pure vanadium double as much nitrogen as the alloy V 3Ti 1Si. - N diffuses into the bulk of both materials, whilst C is bound near the surface. The hardening at the surface is due to the up-take of N. - The vanadium-carbonitride-, respectively the vanadium-titanium-nitride-layers have a strong influence on the weight loss and the up-take of non-metals. - The magnetic trap reduces the weight loss of vanadium in a significant way. The positive influence of the magnetic trap is supposed to be due to the reduction of the nitrogen content of Li. - The corrosion rates of the alloy V 3Ti 1Si show, that the dissolution due to V loss does not affect the lifetime of the alloy. The comparison with steels and nickle-base-alloys demonstrates the advantages of this material. Nevertheless, the purification of the Li and the control of its nonmetal-levels is indispensable. (orig./HP)

  1. Influence of the austenite-martensite transformation in the dimensional stability of a new tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.); Influencia de la transformacion austenita-martensita en la estabilidad dimensional de un nuevo acero para herramientas aleado con niobio (0,08%) y vanadio (0,12%)

    Conejero Ortega, G.; Candela Vazquez, N.; Pichel Martinez, M.; Barea del Cerro, R.; Carsi Cebrian, M.

    2014-07-01

    Austenite-martensite transformation influence on the dimensional stability of a new experimental tool steel alloyed with niobium (0.08% wt.) and vanadium (0.12% wt.) has been studied. The dimensional stability of this new steel was compared with the dimensional stability of commercial steel, after and before two thermal treatments, T1 (860 degree centigrade) and T2 (900 degree centigrade). The thermal treatments consisted on heating and cooling, at 1 atmosphere of pressure, in N{sub 2} atmosphere furnace, following by heating in a conventional furnace at 180 degree centigrade during 1 hour. Initially, the experimental steel composition and Ac{sub 1} and Ac{sub 3} transformation temperatures were determined by glow-discharge luminescence (GDL) and dilatometric tests, respectively, in order to select the austenization temperatures of T1 and T2 treatments. After hardness measurement, the microstructure of both steels was characterized by X-Ray Diffraction (XRD) and optical metallography, before and after of T1 and T2 thermal treatments. Finally, longitudinal and angular dimensional stability analyses were realized for both commercial and experimental steels. After a contrastive hypothesis analysis, the results showed that the longitudinal relative variation of the experimental steel calculated was around 0.2% and the angular relative variation was not significant. (Author)

  2. Radiochemical reprocessing of V-Cr-Ti alloy and its feasibility study

    An extraction scheme for radiochemical reprocessing of an activated vanadium-chromium-titanium alloy after a fusion reactor decommissioning was developed and checked experimentally. It is based on extraction of V, Cr and Ti freed of activation products from the alloy dissolved in nitric acid. The solution of di-2-ethyl-hexyl-phosphoric acid (D2EHPA) in a hydrocarbon solvent (dodecane) serves as an extractant. It takes 50 extraction steps to recover V, Cr and Ti down to an effective dose rate <12.5 μSv/h, permitting the refabrication of these metals without biological shielding from ionizing radiation. Technical and economic analysis suggests that the reprocessing alternative is more attractive economically than the burial of spent V-Cr-Ti alloy components

  3. Characterization of vanadium flow battery

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2010-10-15

    This report summarizes the work done at Risoe DTU testing a vanadium flow battery as part of the project 'Characterisation of Vanadium Batteries' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  4. Use of vanadium in the production of cryostats and ovens for neutro-crystallographic experiments

    The scattering of neutrons by vanadium is incoherent, and thus this metal is of great interest in the construction of cryostats and ovens. As no diffusion peak is expected at finite angles, the use of vanadium prevents the difference techniques to be used with other materials. Thin vanadium tubes have been manufactured at Saclay which can be soldered or brazed on other metals or alloys. Several techniques of soldering, brazing, etc..., are registered, with which we have obtained non brittle and leak free joints. Description of a cryostat designed to operate at 4 deg. K and of an oven operating between 50 deg. C and 1000 deg. C with very low thermal gradient is given at full length. (authors)

  5. On the comparison of microstructural characteristics and mechanical properties of high-vanadium austenitic manganese steels with the Hadfield steel

    Highlights: ► Mechanical properties of HV-AMS are affected by the type and distribution of VCs. ► Solution treatment of Hadfield steels has no significant effect on HV-AMS alloys. ► HV-AMS alloys have superior wear resistance compared with Hadfield steels. - Abstract: In this study, high-vanadium austenitic manganese steel (HV-AMS) alloys and the standard Hadfield steel were investigated. The microstructure of these high-vanadium alloyed Hadfield steels was studied thoroughly using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and was compared to the Hadfield steel. The hardness and unnotched Charpy impact strength of HV-AMS alloys and Hadfield steel were examined at ambient temperature in the as-cast and heat-treated conditions. A pin-on-disk wear test at linear speed of 10 m/min and a 55 N normal load was employed to evaluate the wear behavior of both steel samples. Microstructural results showed that varying the carbon content in HV-AMS alloys can affect the vanadium carbide morphology and its distribution in the austenite matrix which leads to considerable changes of the mechanical properties. Abrasion test revealed that HV-AMS alloys have superior wear resistance, about 5 times of the standard Hadfield steel.

  6. Chromium activity measurements in nickel based alloys for very high temperature reactors: Inconel 617, haynes 230 and model alloys - HTR2008-58147

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHX) of (V)-HTR reactors. The behaviour under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer Then, the alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow [1]. To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T∼1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617 and model alloys 1178, 1181, 1201. This coupling makes it possible thermodynamic equilibrium to be obtained between the vapour phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (/) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared to that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behaviour in these alloys. These activity results call into question those previously measured by Hilpert [2], largely used in the literature. (authors)

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

    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.

  8. Vanadium oxide dissolution in sodium carbonate solutions

    Cherkashin, V.I.; Doroshenko, V.P.; Goncharov, I.A.; Denisova, G.V. (Zaporozhskij Industrial' nyj Inst. (Ukrainian SSR))

    1983-01-01

    Kinetics of dissolution process of powdered vanadium (5) oxide in sodium carbonate is studied. Activation energy of chemical dissolution of V/sub 2/O/sub 5/ at sodium carbonate concentration up to 0.6 mol/dm/sup 3/ constitutes 35.2 kJ/mol. With sodium carbonate concentration increase the dissolution activation energy decreases to 32.5 kJ/mol. Absolute values of activation energy of the dissolution process, dependence of the reaction order on the temperature in the range of low sodium carbonate concentration, testify to the presence of kinetic difficulties in the process studied. Thus, the process of V/sub 2/O/sub 5/ dissolution in sodium carbonate solutions proceeds in the mixed region and obeys regularities of the mixed kinetics.

  9. Reaction diffusion in the vanadium-zirconium system

    Reaction diffusion in the vanadium-zirconium system has been studied in the temperature range 1273 to 1473 K by use of two types of semi-infinite couples, (pure V)-(pure Zr) and (pure V)-(Zr-13.5 at % V alloy) and a sandwich type couple, (pure V)-(pure Zr foil of 50 to approx. 200 μm)-(pure V). In all three types of couples diffused above 1373 K parabolic growth of the V2Zr phase layer has been observed after respective incubation times. At 1473 K, the incubation time in the (pure V)-(pure Zr) couple is 24 h, however, it is 1 h in the (pure V)-(pure Zr foil of 50 μm)-(pure V) couple and nearly zero in the (pure V)-(Zr-13.5 at % V alloy) couple. This suggests that for nucleation of the V2Zr phase during the reaction diffusion, the concentration at the interface of the phase boundary between the β-phase and the γ-phase is required to reach the nearly equilibrium one. It has been found that at the lower diffusion temperature the uphill diffusion of vanadium from the β-phase contributes in part to growth of the V2Zr layer. In addition to the V2Zr phase, another phase, VZr, has been formed in the (pure V)-(pure Zr) couple diffused at 1473 K for more than 230 h. (author)

  10. Suppression of the critical temperature in binary vanadium hydrides

    Highlights: • Addition of 10 mol% Cr to V increases the β-hydride TC to >200 °C. • Addition of 10 mol% Ni to V increases the β-hydride TC to >400 °C. • Addition of 10 mol% Al to V decreases the β-hydride TC to 90Al10 membrane can be cycled to 2 without β-hydride formation. -- Abstract: The tendency of vanadium-based alloy membranes to embrittle is the biggest commercialisation barrier for this hydrogen separation technology. Excessive hydrogen absorption and the α → β hydride transition both contribute to brittle failure of these membranes. Alloying is known to reduce absorption, but the influence of alloying on hydride phase formation under conditions relevant to membrane operation has not been studied in great detail previously. Here, the effect of Cr, Ni, and Al alloying additions on V–H phase equilibrium has been studied using hydrogen absorption measurements and in situ X-ray diffraction studies. The addition of 10 mol% Ni increases the critical temperature for α + β hydride formation to greater than 400 °C, compared to 170 °C for V. Cr also increases the critical temperature, to between 200 and 300 °C. The addition of 10 mol% Al, however, suppresses the critical temperature to less than 30 °C, thereby enabling this material to be cycled thermally and hydrostatically while precluding formation of the β-hydride phase. This is despite Al also decreasing hydrogen absorption. The implication of this finding is that one of the mechanisms of brittle failure in vanadium-based hydrogen-selective membranes has been eliminated, thereby increasing the robustness of this material relative to V

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

    Yang, Jinyan; Tang, Ya; Yang, Kai [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Rouff, Ashaki A. [School of Earth and Environmental Sciences, Queens College City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367 (United States); Elzinga, Evert J. [Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ (United States); Huang, Jen-How, E-mail: jen-how.huang@unibas.ch [Institute of Environmental Geosciences, University of Basel, CH-4056 Basel (Switzerland)

    2014-01-15

    Highlights: • Vanadium in the soil and mine tailings has low solubility. • The leachability of vanadium in the mine tailings is lower than in the soil. • Low risk of vanadium migrating from the soil and mine tailings into the surrounding environment. • Drought and rewetting increase vanadium release from the soil and mine tailings. • Soil leaching processes control vanadium transport in soils overlain with mine tailings. -- Abstract: 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 20 μg L{sup −1} to 50–90 μg L{sup −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.

  12. Superior Electrocatalytic Activity of a Robust Carbon-Felt Electrode with Oxygen-Rich Phosphate Groups for All-Vanadium Redox Flow Batteries.

    Kim, Ki Jae; Lee, Heon Seong; Kim, Jeonghun; Park, Min-Sik; Kim, Jung Ho; Kim, Young-Jun; Skyllas-Kazacos, Maria

    2016-06-01

    A newly prepared type of carbon felt with oxygen-rich phosphate groups is proposed as a promising electrode with good stability for all-vanadium redox flow batteries (VRFBs). Through direct surface modification with ammonium hexafluorophosphate (NH4 PF6 ), phosphorus can be successfully incorporated onto the surface of the carbon felt by forming phosphate functional groups with -OH chemical moieties that exhibit good hydrophilicity. The electrochemical reactivity of the carbon felt toward the redox reactions of VO(2+) /VO2 (+) (in the catholyte) and V(3+) /V(2+) (in the anolyte) can be effectively improved owing to the superior catalytic effects of the oxygen-rich phosphate groups. Furthermore, undesirable hydrogen evolution can be suppressed by minimizing the overpotential for the V(3+) /V(2+) redox reaction in the anolyte of the VRFB. Cell-cycling tests with the catalyzed electrodes show improved energy efficiencies of 88.2 and 87.2 % in the 1(st) and 20(th)  cycles compared with 83.0 and 81.1 %, respectively, for the pristine electrodes at a constant current density of 32 mA cm(-2) . These improvements are mainly attributed to the faster charge transfer allowed by the integration of the oxygen-rich phosphate groups on the carbon-felt electrode. PMID:27106165

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

    Mueller, Michael; Baik, Seungyun [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Jeon, Hojeong; Kim, Yuchan [Center for Biomaterials, Biomedical Research Institute Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Jungtae [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Kim, Young Jun, E-mail: youngjunkim@kist-europe.de [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany)

    2015-05-15

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V{sub 2}O{sub 5} 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 V{sub 2}O{sub 5} 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 V{sub 2}O{sub 5} precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/V{sub x}O{sub x} composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V{sub 2}O{sub 5} composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure

  14. Leaching of vanadium, sodium, and silicon from molten V-Ti-bearing slag obtained from low-grade vanadium-bearing titanomagnetite

    Zhu, Yuan-yuan; Yi, Ling-yun; Zhao, Wei; Chen, De-sheng; Zhao, Hong-xin; Qi, Tao

    2016-08-01

    The water leaching process of vanadium, sodium, and silicon from molten vanadium-titanium-bearing (V-Ti-bearing) slag obtained from low-grade vanadium-bearing titanomagnetite was investigated systematically. The results show that calcium titanate, sodium aluminosilicate, sodium oxide, silicon dioxide and sodium vanadate are the major components of the molten V-Ti-bearing slag. The experimental results indicate that the liquid-solid (L/S) mass ratio significantly affects the leaching process because of the respective solubilities and diffusion rates of the components. A total of 83.8% of vanadium, 72.8% of sodium, and 16.1% of silicon can be leached out via a triple counter-current leaching process under the optimal conditions of a particle size below 0.074 mm, a temperature of 90°C, a leaching time of 20 min, an L/S mass ratio of 4:1, and a stirring speed of 300 r/min. The kinetics of vanadium leaching is well described by an internal diffusion-controlled model and the apparent activation energy is 11.1 kJ/mol. The leaching mechanism of vanadium was also analyzed.

  15. Vanadium(5) sorption from weakly acid solutions

    Distribution of vanadium(5) between diluted solutions of sulfuric acid and macroporous polymer sorbent impregnated by a mixture of nitrogen-containing phenol-formaldehyde resol oligomer (R) and tributylphosphate has been studied. It has been ascertained that under the conditions mentioned vanadium transfers to solid phase as a mixture of chelates with stoichiometric ratio V:R = 1:1 and 2:1. During sorption by impregnated sorbent R capacity in terms of vanadium increases essentially as compared with solvent extraction

  16. Determination of the oxidation state and coordination of a vanadium doped chalcogenide glass

    Hughes, MA; Curry, RJ; Hewak, DW

    2011-01-01

    Vanadium doped chalcogenide glass has potential as an active gain medium, particularly at telecommunications wavelengths. This dopant has three spin allowed absorption transitions at 1100, 737 and 578 nm, and a spin forbidden absorption transition at 1000 nm. X-ray photo electron spectroscopy indicated the presence of vanadium in a range of oxidation states from V+ to V5+. Excitation of each absorption band resulted in the same characteristic emission spectrum and lifetime, indicating that on...

  17. Dissolution kinetics and thermodynamic analysis of vanadium trioxide during pressure oxidation

    2012-01-01

    The dissolution kinetics of vanadium trioxide in sulphuric acid-oxygen medium was examined. It was determined that the concentration of sulphuric acid and stirring speed above 800 r min 1 did not significantly affect vanadium extraction. The dissolution rate increased with increasing temperature and oxygen partial pressure, but decreased with increasing particle size. The dissolution kinetics was controlled by the chemical reaction at the surface with the estimated activation energy of 43.46 kJ·mol-1. The l...

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

    Elena V. Fedorova; 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 coor...

  19. Doped vanadium oxides phase transitions vapors influence

    N.Y. Shishkin; A.A. Komarov; D.V. Kosov; V.A. Cherkasov; Bashkirov, L. A.; Bardi, U; Y.K. Gunko

    2005-01-01

    The methods of vanadium dioxide synthesis were developed. The first one is based on the decomposition of vanadyl oxalate VOC2O4 obtained by the dissolution of vanadium oxide (V) in ethanedioic acid solution with consequent heating. The second one uses the magnetron sputtering of metallic vanadium with its consequent soft oxidation. Investigations of the transition temperature in vanadium dioxide influence by the material doping and adding MoO3, Bi2O3, SnO2, NiO, CuO, Co3O4 as well as by the pre...

  20. Vanadium irradiation at ATR - neutronics aspects

    Gomes, I.C.; Smith, D.L. [Argonne National Laboratory, Chicago, IL (United States)

    1995-04-01

    Calculations were performed to estimate damage and transmutation rates in vanadium irradiated in the ATR (Advanced Test Reactor) located in Idaho. The main focuses of the study are to evaluate the transmutation of vanadium to chromium and to explore ways to design the irradiation experiment to avoid excessive transmutation. It was found that the A-hole of ATR produces damage rate of {approximately} 0.2%/dpa of vanadium to chromium. A thermal neutron filter can be incorporated into the design to reduce the vanadium-to-chromium transmutation rate to low levels. A filter 1-2 mm thick of gadolinium or hafnium can be used.

  1. Catalytic oxidations by vanadium complexes

    Ligtenbarg, A.G J; Hage, R.; Feringa, B. L.

    2003-01-01

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the appropriate conditions. The most interesting model compounds that have been synthesised and studied as bromination catalysts, and catalysts for, i.e. epoxidation, hydroxylation, sulfoxidation and alco...

  2. Investigation of corrosion of alloys using neutron activation and gamma-ray spectrometry. Pt. 1

    A simple procedure is proposed for studying differential (selective) corrosion of alloys using the radioactive tracer technique. This procedure is based on the neutron activation of samples, and the measurement of the γ-ray spectra of irradiated samples and their corrosion products. The reliability of the given method has been demonstrated by application to conventional and spheroidal dental amalgams. The method can produce useful results for studying the various factors affecting the properties of dental amalgams as well as other alloys. A week after end of irradiation of dental amalgam only the isotopes 65Zn, sup(110m)Ag, 113Sn and 203Hg are excepted to have significant activites. Samples were irradiated in the Egyptian Reactor (RR-I) at Inshas for 5 hours. The neutron flux was approximately 1x1013n cm-2s-1. (F.G.)

  3. Microstructure of hypereutectic Fe-C-V alloys

    M. Kawalec

    2011-01-01

    The study shows the results of examinations of the microstructure of the in-volume-solidifying Fe-C-V alloys containing carbon in a rangeof 1.53÷3.09% and vanadium in a range of 14.73÷15.71%. All the examined alloys were hypereutectic alloys as proved by the coolingcurves, relevant calculations (Sc) and examinations under the microscope. It has been confirmed that the primary carbides of vanadium are crystallising in the form of non-faceted dendrites, acting as a substrate for the growing fib...

  4. Oxygen reduction reaction activity on Pt{111} surface alloys.

    Attard, Gary A; Brew, Ashley; Ye, Jin-Yu; Morgan, David; Sun, Shi-Gang

    2014-07-21

    PtM overlayers (where M=Fe, Co or Ni) supported on Pt{111} are prepared via thermal annealing in either a nitrogen/water or hydrogen ambient of dilute aqueous droplets containing M(Z+) cations directly attached to the electrode. Two different PtM phases are detected depending on the nature of the post-annealing cooling environment. The first of these consists of small (hydroxides. The second type of PtM phase is prepared by cooling in a stream of hydrogen gas. Although this second phase also consists of numerous microcrystals covering the Pt{111} electrode surface, these are both flatter than before and moreover are entirely metallic in character. A positive shift in the onset of PtM oxide formation correlates with increased activity towards the oxygen reduction reaction (ORR), which we ascribe to the greater availability of platinum metallic sites under ORR conditions. PMID:24986646

  5. Characterization of Vanadium Flow Battery

    Bindner, Henrik W.; Krog Ekman, Claus; Gehrke, Oliver;

    This report summarizes the work done at Risø-DTU testing a vanadium flow battery as part of the project “Characterisation of Vanadium Batteries” (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery...... has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risø DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of...... wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses...

  6. Process for the manufacture of multi-filament superconductor wires made of Nb3Sn or V3Ga filaments, embedded in a copper or Cu alloy matrix, which contains additional metal elements, with pre-determined superconductor properties

    The following are claimed: a) The additional metal elements of niobium or niobium alloys of the group Nb-Ta, Nb-Ti, Nb-Zr or of vanadium or vanadium alloys of the group V-Ta, V-Ti, V-Zr, and b) the powder metallurgy treatment. (GG)

  7. Studies on separation and purification of fission 99Mo from neutron activated uranium aluminum alloy

    A new method has been developed for separation and purification of fission 99Mo from neutron activated uranium–aluminum alloy. Alkali dissolution of the irradiated target (100 mg) results in aluminum along with 99Mo and a few fission products passing into solution, while most of the fission products, activation products and uranium remain undissolved. Subsequent purification steps involve precipitation of aluminum as Al(OH)3, iodine as AgI/AgIO3 and molybdenum as Mo-α-benzoin oxime. Ruthenium is separated by volatilization as RuO4 and final purification of 99Mo was carried out using anion exchange method. The radiochemical yield of fission 99Mo was found to be >80% and the purity of the product was in conformity with the international pharmacopoeia standards. - Highlights: • 99Mo separation, purification method developed from neutron activation of 100 g U–Al alloy. • Uranium, fission, activation product decontamination by alkali dissolution of activated target. • Purification by Al(OH)3, AgI/AgIO3, Mo-α-benzoin oxime precipitation and anion exchange. • Very high decontamination factors for alpha activity obtained. • Final 99Mo product (recovery >80%) complied with international pharmacopoeia standards

  8. Understanding the effect of steps, strain, poisons, and alloying: Methane activation on Ni surfaces

    Abild-Pedersen, Frank; Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2005-01-01

    It is shown that a single parameter characterizing the electronic structure of a transition metal surface, the d-band center (epsilon(d)), can be used to provide a unified description of a range of phenomena in heterogeneous catalysis. Using methane activation on Ni surfaces as an example, we show...... that variations in epsilon(d) can be used to quantitatively describe variations in the activation energy when the surface structure is changed, when the coverage of carbon is changed, when the surface is strained, when the surface is alloyed, and when the surface is poisoned by sulfur. The d...

  9. Titanium-Nickel Shape Memory Alloy Spring Actuator for Forward-Looking Active Catheter

    Shozo Inoue; Takahiro Miki; Takafumi Tsurui; Hiroyuki Nagasawa; Mamoru Komatsubara; Takahiro Namazu

    2011-01-01

    The fabrication and characterization of forward-looking active catheter actuated by titanium-nickel (Ti-Ni) shape memory alloy (SMA) springs are described. The catheter has been designed for wide-range observation of an affected area inside a blood vessel when the blood vessel is occluded. The developed active catheter consists of eight Ti-Ni SMA spring actuators for actuation of catheter tip, an ultrasonic transducer for forward-looking, a guide wire, a polyurethane tube for coating, and spi...

  10. Dislocation development in V-5CR-5TI and pure vanadium

    Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States); Grossbeck, M.L. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    The objective of this work is to explain notch sensitivity noted in the candidate alloy V-5Cr-5Ti. Microstructural examinations have been performed on deformed tensile specimens of V-5Cr-5Ti and pure vanadium in order to explain notch sensitivity noted in the candidate alloy V-5Cr-5Ti. SS-3 tensile specimens have been prepared, stress relieved and deformed to 5% strain. The resulting deformation structures have been examined by transmission electron microscopy. It is found that 5% deformation in V-5Cr-5Ti produces a higher dislocation density consisting of long straight dislocations, typical of Stage II, and many small loops, whereas in pure vanadium, the dislocation arrangements are more complex, typical of Stage III, and the small loops are at a lower density.

  11. Capacity decay and remediation of nafion-based all-vanadium redox flow batteries.

    Luo, Qingtao; Li, Liyu; Wang, Wei; Nie, Zimin; Wei, Xiaoliang; Li, Bin; Chen, Baowei; Yang, Zhenguo; Sprenkle, Vincent

    2013-02-01

    The relationship between electrochemical performance of vanadium redox flow batteries (VRBs) and electrolyte composition is investigated, and the reasons for capacity decay over charge-discharge cycling are analyzed and discussed herein. The results show that the reasons for capacity fading over real charge-discharge cycling include not only the imbalanced vanadium active species, but also the asymmetrical valence of vanadium ions in positive and negative electrolytes. The asymmetrical valence of vanadium ions leads to a state-of-charge (SOC)-range decrease in positive electrolytes and a SOC-range increase in negative electrolytes. As a result, the higher SOC range in negative half-cells further aggravates capacity fading by creating a higher overpotential and possible hydrogen evolution. Based on this finding, we developed two methods for restoring lost capacity, thereby enabling long-term operation of VRBs to be achieved without the substantial loss of energy resulting from periodic total remixing of electrolytes. PMID:23208862

  12. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Ana Lorena Alvarado-Gámez

    2014-02-01

    Full Text Available 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.

  13. The electrochemical catalytic activity of single-walled carbon nanotubes towards VO2+/VO2+ and V3+/V2+ redox pairs for an all vanadium redox flow battery

    Highlights: ► SWCNT shows excellent electrochemical catalytic activity towards VO2+/VO2+ and V3+/V2+ redox couples. ► The anodic reactions are more sensitive to the surface oxygen atom content change compared with the cathodic reactions. ► The enhanced battery performance clearly demonstrated that the SWCNT is suitable to be used as an electrode catalyst for VRFB. - Abstract: Single-walled carbon nanotube (SWCNT) was used as an electrode catalyst for an all vanadium redox flow battery (VRFB). The electrochemical property of SWCNT towards VO2+/VO2+ and V3+/V2+ was carefully characterized by cyclic voltammetric (CV) and electrochemical impedance spectroscopy (EIS) measurements. The peak current values for these redox pairs were significantly higher on the modified glassy carbon electrode compared with those obtained on the bare electrode, suggesting the excellent electrochemical activity of the SWCNT. Moreover, it was proved that the anodic process was more dependent on the surface oxygen of the SWCNT than the cathodic process through changing its surface oxygen content. Detailed EIS analysis of different modified electrodes revealed that the charge and mass transfer processes were accelerated at the modified electrode–electrolyte interface, which could be ascribed to the large specific surface area, the surface defects and the oxygen functional groups of the SWCNT. The enhanced battery performance effectively demonstrated that the SWCNT was suitable to serve as an electrode catalyst for the VRFB.

  14. PdM (M = Pt, Au) bimetallic alloy nanowires with enhanced electrocatalytic activity for electro-oxidation of small molecules

    Zhu, Chengzhou; Guo, Shaojun; Dong, Shaojun [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022 (China)

    2012-05-02

    A facile and general method has been developed to synthesize well-defined PdPt and PdAu alloy nanowires, which exhibit significantly enhanced activity towards small molecules, such as ethanol, methanol, and glucose electro-oxidation in an alkaline medium. Considering the important role of one-dimensional alloy nanowires in electrocatalytic systems, the present Pd-based alloy nanostructures could offer a promising new class of advanced electrocatalysts for direct alcohol fuel cells and electrochemical sensors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Highlights: • Vanadium in the soil and mine tailings has low solubility. • The leachability of vanadium in the mine tailings is lower than in the soil. • Low risk of vanadium migrating from the soil and mine tailings into the surrounding environment. • Drought and rewetting increase vanadium release from the soil and mine tailings. • Soil leaching processes control vanadium transport in soils overlain with mine tailings. -- Abstract: 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 to 50–90 μg L−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

  16. Grain boundary premelting and activated sintering in binary refractory alloys

    Shi, Xiaomeng

    Quasi-liquid intergranular film (IGF) which has been widely observed in ceramic systems can persist into sub-solidus region whereby an analogy to Grain boundary (GB) premelting can be made. In this work, a grain boundary (GB) premelting/prewetting model in a metallic system was firstly built based on the Benedictus' model and computational thermodynamics, predicting that GB disordering can start at 60-85% of the bulk solidus temperatures in selected systems. This model quantitatively explains the long-standing mystery of subsolidus activated sintering in W-Pd, W-Ni, W-Co, W-Fe and W-Cu, and it has broad applications for understanding GB-controlled transport kinetics and physical properties. Furthermore, this study demonstrates the necessity of developing GB phase diagrams as a tool for materials design. Subsequently, Grain boundary (GB) wetting and prewetting in Ni-doped Mo are systematically evaluated via characterizing well-quenched specimens and thermodynamic modeling. In contrast to prior reports, the delta-NiMo phase does not wet Mo GBs in the solid state. In the solid-liquid two-phase region, the Ni-rich liquid wets Mo GBs completely. Furthermore, high-resolution transmission electron microscopy demonstrates that nanometer-thick quasi-liquid IGFs persist at GBs into the single-phase region where the bulk liquid phase is no longer stable; this is interpreted as a case of GB prewetting. An analytical thermodynamic model is developed and validated, and this model can be extended to other systems. Furthermore, the analytical model was refined based upon Beneditus' model with correction in determining interaction contribution of interfacial energy. A calculation-based GB phase diagram for Ni-Mo binary system was created and validated by comparing with GB diffusivities determined through a series of controlled sintering experiments. The dependence of GB diffusivity on doping level and temperature was examined and compared with model-predicted GB phase diagram. The

  17. Hollow raspberry-like PdAg alloy nanospheres: High electrocatalytic activity for ethanol oxidation in alkaline media

    Peng, Cheng; Hu, Yongli; Liu, Mingrui; Zheng, Yixiong

    2015-03-01

    Palladium-silver (PdAg) alloy nanospheres with unique structure were prepared using a one-pot procedure based on the galvanic replacement reaction. Their electrocatalytic activity for ethanol oxidation in alkaline media was evaluated. The morphology and crystal structure of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical characterization techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical performance of the PdAg alloy nanospheres. The SEM and TEM images showed that the PdAg alloy nanospheres exhibit a hierarchical nanostructure with hollow interiors and porous walls. Compared to the commercial Pd/C catalyst, the as-prepared PdAg alloy nanospheres exhibit superior electrocatalytic activity and stability towards ethanol electro-oxidation in alkaline media, showing its potential as a new non-Pt electro-catalyst for direct alcohol fuel cells (DAFCs).

  18. Transmutation of alloys in MFE facilities as calculated by REAC (a computer code system for activation and transmutation)

    A computer code system for fast calculation of activation and transmutation has been developed. The system consists of a driver code, cross-section libraries, flux libraries, a material library, and a decay library. The code is used to predict transmutations in a Ti-modified 316 stainless steel, a commercial ferritic alloy (HT9), and a V-15%Cr-5%Ti alloy in various magnetic fusion energy (MFE) test facilities and conceptual reactors

  19. Influence of strain rate on the twin and slip activity of a magnesium alloy containing neodymium

    Dudamell, N.V. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Hidalgo-Manrique, P., E-mail: paloma.hidalgo@imdea.org [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Chakkedath, A.; Chen, Z.; Boehlert, C.J. [Michigan State University, East Lansing, MI 48824-1226 (United States); Gálvez, F. [ETS Ingenieros de Caminos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Yi, S.; Bohlen, J.; Letzig, D. [Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht (Germany); Pérez-Prado, M.T. [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain)

    2013-10-20

    The mechanical behavior of an extruded magnesium–manganese alloy containing 1 wt% of neodymium (MN11) has been investigated at temperatures ranging from room temperature to 400 °C at both quasi-static and dynamic rates. Conventional ex-situ tests, carried out in compression along the extrusion axis (EA), have been combined with in-situ tests in a scanning electron microscope (SEM) in order to elucidate the effect of a rare earth (RE) addition on the dominant deformation mechanisms. An unusually large activity of twinning was observed at room temperature in a wide range of quasi-static rates. Furthermore, the twinning activity has been found to increase at temperatures around 250 °C, where clear signs of dynamic strain aging (DSA) are also apparent. The enhanced twinning activity compared to conventional Mg alloys, not containing RE elements, is attributed to an increase in the critical resolved shear stress of basal slip (CRSS{sub basal}) due to the presence of intermetallic RE-containing particles and to the Nd atoms in solid solution. The surprising decrease of the twinning activity at dynamic rates (∼10{sup 3} s{sup −1}) may be explained by a decrease in the CRSS{sub basal} as the intermetallic RE-containg particles and the Nd solid solution strengthening become less effective with increasing strain rate.

  20. Influence of strain rate on the twin and slip activity of a magnesium alloy containing neodymium

    The mechanical behavior of an extruded magnesium–manganese alloy containing 1 wt% of neodymium (MN11) has been investigated at temperatures ranging from room temperature to 400 °C at both quasi-static and dynamic rates. Conventional ex-situ tests, carried out in compression along the extrusion axis (EA), have been combined with in-situ tests in a scanning electron microscope (SEM) in order to elucidate the effect of a rare earth (RE) addition on the dominant deformation mechanisms. An unusually large activity of twinning was observed at room temperature in a wide range of quasi-static rates. Furthermore, the twinning activity has been found to increase at temperatures around 250 °C, where clear signs of dynamic strain aging (DSA) are also apparent. The enhanced twinning activity compared to conventional Mg alloys, not containing RE elements, is attributed to an increase in the critical resolved shear stress of basal slip (CRSSbasal) due to the presence of intermetallic RE-containing particles and to the Nd atoms in solid solution. The surprising decrease of the twinning activity at dynamic rates (∼103 s−1) may be explained by a decrease in the CRSSbasal as the intermetallic RE-containg particles and the Nd solid solution strengthening become less effective with increasing strain rate

  1. Activation energies for oxygen reduction on platinum alloys: theory and experiment.

    Anderson, Alfred B; Roques, Jérôme; Mukerjee, Sanjeev; Murthi, Vivek S; Markovic, Nenad M; Stamenkovic, Vojislav

    2005-01-27

    A combined theoretical and experimental analysis of the electrode potential dependencies of activation energies is presented for the first step in oxygen reduction over platinum and platinum alloy catalysts in both polycrystalline and carbon supported form. Tafel data for several of the catalysts are used to predict potential-dependent activation energies for oxygen reduction over the 0.6-0.9 V range in strong and weak acid. Comparisons with the theoretical curve show good agreement above 0.8 V, suggesting a fairly constant preexponential factor. Arrhenius determinations of activation energies over the 0.7-0.9 V range yield little trend for weak acid, possibly because of the larger uncertainties in the Arrhenius fits, but the strong acid results have smaller uncertainties and for them the measured activation energies trend up with potential. PMID:16851081

  2. 全钒离子氧化还原液流电池电极活性物质的研究%Study on Electrode Active Materials for all Vanadium Redox Flow Battery

    张环华; 肖楚民; 张平民

    2000-01-01

    介绍了以VOSO4为原料,电解制备全钒离子氧化还原液流电池的正极活性物质V(Ⅴ)盐和负极活性物V(Ⅱ)盐,并用循环伏安法研究了它们在石墨电极上的电化学性质。结果表明,在硫酸溶液中,作为全钒电池的正极和负极V(Ⅴ)/V(Ⅳ)和V(Ⅲ)/V(Ⅱ)电对在石墨电极上的氧化还原反应均为单电子准可逆过程.%Electrolytic method to prepare positive and negative active materials from VOSO4 sulphuric acid solution for all vanadium redox flow battery is described. V(Ⅴ)salt is obtained in anode area and V(Ⅱ) salt is in cathode area. The electrochemical behaviour of the two series salt on graphite electrode have also been studied by cyclic voltammetry. The results showed that the redox reactions of V(Ⅴ)/V(Ⅳ) and V(Ⅲ)/V(Ⅱ) couples in sulfuric adid,which are used for anolyte and catholyte in a redox flow battery,is qusi-reversible.

  3. Effect of silicon on the structure and mechanical properties of high-vanadium cast iron

    E. Fraś; M. Kawalec

    2009-01-01

    The results of microstructural examinations and mechanical tests carried out on Fe-C-V and Fe-C-V-Si alloys solidifying in volumetric mode, containing 1,38-1,83%C, 6,76-14,72%V and 1,05-3,69 Si, have been reported. The eutectic crystallising in Fe-C-V alloys is composed of ferrite and vanadium carbides of the VC1-x type, and as such is included in the group of fibrous eutectics. Introducing silicon additions to the Fe-C-V system changes the geometry of the solidifying eutectic from fibrous to...

  4. One-Dimensional Vanadium Nitride Nanofibers Fabricated by Electrospinning for Supercapacitors

    Vanadium nitride has been the hot material for supercapacitors due to its excellent electrical conductivity and high specific capacitance. However, vanadium nitride nanoparticle usually suffers a poor performance due to its aggregation and lack of effective contact. In this work, one-dimensional (1D) vanadium nitride nanofibers are prepared by a combination of electrostatic spinning and high-temperature calcination in ammonia. The cross-linked nanofibers composed of nanoparticles construct a facile transport path for charge and electrolyte ion. Moreover, vanadium nitride nanoparticles encapsulated into carbon prevent grain growth and aggregation, which provide more active sites for electrolyte ion. Owing to this unique structure, vanadium nitride nanofibers exhibit high specific capacitance of 291.5 F g−1 at 0.5 A g−1 and rate capability with a capacitance of 105.1 F g−1 at 6 A g−1. In addition, we find that annealing temperature has significant influence on the performance of vanadium nitride, which associates with fibrous structure and crystallinity, and a limited potential window can greatly improve the cycling stability (retains 50% of initial capacitance after 1000 cycles)

  5. A method to determine the active particle nucleation undercooling distribution in a refined alloy

    We propose a method to determine the active particle distribution of nucleation undercooling in a refined alloy. The experimental data used in this work are inferred from solidification experiments on a refined Al-3.5 wt% Ni alloy performed with X-ray radiography at the European Synchrotron Radiation Facility. These in situ and real time observations allow the accurate and direct determination of the grain origin (heterogeneous nucleation on particles or fragmentation), of the density and of the equiaxed front growth rate. The LGK classical dendrite growth model is used to evaluate the front undercooling (ΔTC) corresponding to the measured equiaxed front growth rate. Then, the corresponding cumulative distribution of active refining particles is determined. From this cumulative distribution, we derive the corresponding Gaussian and log-normal laws to obtain the nucleation undercooling distribution of active particles. Results are discussed and compared to available measurements in the literature. The standard particle distribution parameters (density of nuclei, mean nucleation undercooling and standard deviation) are determined. We plan to use the determined nucleation undercooling particle distribution in a stochastic CAFE model for the grain structure without preliminary adjustment of the nucleation undercooling.

  6. Tritium removal using vanadium hydride

    The results of an initial examination of the feasibility of separation of tritium from gaseous protium-tritium mixtures using vanadium hydride in cyclic processes is reported. Interest was drawn to the vanadium-hydrogen system because of the so-called inverse isotope effect exhibited by this system. Thus the tritide is more stable than the protide, a fact which makes the system attractive for removal of tritium from a mixture in which the light isotope predominates. The initial results of three phases of the research program are reported, dealing with studies of the equilibrium and kinetics properties of isotope exchange, development of an equilibrium theory of isotope separation via heatless adsorption, and experiments on the performance of a single heatless adsorption stage. In the equilibrium and kinetics studies, measurements were made of pressure-composition isotherms, the HT--H2 separation factors and rates of HT--H2 exchange. This information was used to evaluate constants in the theory and to understand the performance of the heatless adsorption experiments. A recently developed equilibrium theory of heatless adsorption was applied to the HT--H2 separation using vanadium hydride. Using the theory it was predicted that no separation would occur by pressure cycling wholly within the β phase but that separation would occur by cycling between the β and γ phases and using high purge-to-feed ratios. Heatless adsorption experiments conducted within the β phase led to inverse separations rather than no separation. A kinetic isotope effect may be responsible. Cycling between the β and γ phases led to separation but not to the predicted complete removal of HT from the product stream, possibly because of finite rates of exchange. Further experimental and theoretical work is suggested which may ultimately make possible assessment of the feasibility and practicability of hydrogen isotope separation by this approach

  7. Surface structure and catalytic activity of electrodeposited Ni-Fe-Co-Mo alloy electrode by partially leaching Mo and Fe

    LUO Bei-ping; GONG Zhu-qing; REN Bi-ye; YANG Yu-fang; CHEN Meng-jun

    2006-01-01

    Ni-Fe-Mo-Co alloy electrode was prepared in a citrate solution by electrodeposition, and then Mo and Fe were partially leached out from the electrode in 30% KOH solution. The unique surface micromorphology of a hive-like structure was obtained with an average pore size of about 50 nm. The electrode has a very large real surface area and a stable structure. The effects of sodium molybdate concentration on the composition, surface morphology, and structure of electrodes were analyzed by EDS, SEM and XRD. The polarization curves of the different electrodes show that the catalytic activity of electrodes is strongly correlated with the mole fraction of alloy elements (Ni, Fe, Mo, Co), and the addition of cobalt element to Ni-Fe-Mo alloy improves the catalytic activity. The Ni35.63Fe24.67Mo23.52Co16.18 electrode has the best activity for hydrogen evolution reaction(HER), with an over-potential of 66.2 mV, in 30% KOH at 80 ℃ and 200 mA/cm2. The alloy maintains its good catalytic activity for HER during continuous or intermittent electrolysis. Its electrochemical activity and catalytic stability are much higher than the other iron-group with Mo alloy electrodes.

  8. Vanadium molybdenum complex oxide nanotubes

    Nanotubes (NTs) of complex vanadium molybdenum oxide V0.78Mo0.22O2.49(C2H3)0.46 are prepared from the (V1.67Mo0.33O16 · nH2O gel/PVA) composite (PVA stands for poly(vinyl alcohol)) by hydrothermal treatment for 30-50 h at 150-180 deg C. The outer tube diameters are 10-20 and 70-80 nm; the tube lengths are no longer than 1 μm. The X-ray photoelectron and IR spectra, electrical conductivity, and thermal properties of the NTs are studied

  9. Fe-rich border and activation energy of phase decomposition in a Fe–Cr alloy

    Dubiel, S.M., E-mail: Stanislaw.Dubiel@fis.agh.edu.pl; Żukrowski, J.

    2013-08-15

    Concentration of Cr in the Fe-rich α-phase, x, resulted from a phase decomposition caused by an isothermal annealing at T = 415 and 450 °C of a non-irradiated (NR) Fe–Cr14 EFDA sample and that of a He-ions irradiated one (IR) annealed at 415 °C was determined with Mossbauer spectroscopy. The x-value in the latter was by ∼3 at% higher than the one in the NR-counterpart. The activation energy for the phase decomposition in the NR-sample was 122 kJ mol{sup −1}. In the IR-sample its value was by 12 kJ mol{sup −1} lower. Avrami exponents for the NR-samples were close to 0.5, and that the IR-sample had a value of about 1. - Highlights: • Fe-rich border of miscibility gap in Fe–Cr alloys at 415 and 450 °C was determined. • In the He-ion irradiated alloy the miscibility gap at 415 °C was narrower by 3 at%. • Activation energy for the phase separation in non-irradiated samples was 122 kJ mol{sup −1}. • Avrami exponent was 0.5 and 1.0 for non-irradiated and irradiated samples, respectively.

  10. Toxicity of vanadium in female Leghorn chickens.

    Kubena, L F; Phillips, T D

    1983-01-01

    A study was conducted to determine the influence of dietary vanadium, fed after the onset of production, on hen day egg production, body weight changes, and mortality in laying breed chickens. Calcium orthovanadate was fed to 29-week-old female laying breed chickens at calculated levels of 0, 12.5, 25, 50, and 100 ppm dietary vanadium for five consecutive 28-day laying periods. Hen-day egg production and hen body weights were not influenced by the addition of 12.5 or 25 ppm dietary vanadium. Overall hen body weights and the hen day egg production were decreased in hens fed diets to which 50 ppm vanadium was added with a severe reduction in both parameters at 100 ppm. There were no mortalities during the experiment in the groups fed the 0, 12.5, 25, or 50 ppm vanadium diets. Mortality in the group fed the 100 ppm vanadium diet was 11, 39, and 56% at the end of the 28-day Periods 3, 4, and 5, respectively. There were no significant differences in egg weights, although a trend existed for lower egg weights with increasing levels of dietary vanadium. PMID:6828413

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

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

    2016-07-01

    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. PMID:27295523

  12. Alloying effect on the titanium alloys tendency to the salt corrosion

    Salt corrosion tendency of commercial titanium alloys, such as OT4, 0T4-1 (the Ti-Al-Mn system); VT14, VT16 (the Ti-Al-Mo-V system) and VT30 (the Ti-Mo-Sn-Zr system) is compared with the intensity of salt corrosion of VT1-0 titanium and experimental alloys of the Ti-Al and Ti-Mo systems. It is established that the salt corrosion tendency of alloys of the Ti-Al system increases when they are alloyed with manganese and decreases when they are alloyed with vanadium and molybdenum in combination. Alloys of the Ti-Mo system have no tendency to salt corrosion. Alloying with zirconium and tin brings about the propagation of salt corrosion in the alloys

  13. Vanadium pentoxide nanotubes by eelectrospinning

    Lala, Neeta L.; Jose, R.; Yusoff, M. M.

    2012-11-01

    Nanofibers of vanadium pentoxide (V2O5) were synthesized by electrospinning a polymeric solution containing vanadium ion and with subsequent sintering. Conventionally, electrospun TNFs were produced by using a co-axial spinneret; however, TNFs in the present study were obtained by manipulating the concentration ratio of the precursor solution, distance, humidity and flow rate during electrospinning using a single spinneret and sintering with time and temperature change. On the basis of this hypothesis, nanofibers could be altered from elongated 1-D nanofibers to nanowires, nanotubes, spheres and flakes respectively. The surface morphology, structure, roughness and the crystal structure were analyzed using Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), and X-ray diffraction (XRD). The current work has demonstrated a case study for energy storage where V2O5 nanotubes when tested shows the capacitance of 190 Fg-1 in 2M KCl electrolyte indicating an example for the energy storage which may be applicable for other electrochemical devices such as Li-ion batteries, fuel cells, hydrogen storage etc.

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

    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. PMID:24041583

  15. A novel active fire protection approach for structural steel members using NiTi shape memory alloy

    A novel active fire protection approach, based on integrating a shape memory alloy, NiTi, with a steel structure, was proposed to satisfy the fire resistance requirements in structural design. To demonstrate the principles of this approach, a simple structure in the form of a simply supported steel beam was used. The internal action of the beam due to a transverse applied load was reduced by utilizing the shape memory effect in the NiTi alloy at rising temperatures. As a result, the net internal action from the load design was kept below the deteriorated load capacity of the beam during the fire scenario for period of time that was longer than that of the original beam without the NiTi alloy. By integrating the NiTi alloy into the beam system, the structure remained stable even though the steel temperature exceeded the critical temperature which may have caused the original beam structure to collapse. Prior to testing the composite NiTi–steel beam under simulated fire conditions, the NiTi alloy specimens were characterized at high temperatures. At 300 °C, the stiffness of the specimens increased by three times and its strength by four times over that at room temperature. The results obtained from the high-temperature characterization highlighted the great potential of the alloy being used in fire engineering applications. (paper)

  16. Photochemical transformation of vanadium(5) acetylacetonate complexes

    Photochemical transformations of mixed vanadium (5) complex formed as a result of interaction between ethylorthovanadate and acetylacetone which includes in the first coordination sphere vanadyl oxygen, two enolate-ions and enthoxygroup are studied spectrophotometrically and using ESR method. During irradiation of ethanol solutions of the complex a successive reduction of central atom with formation of acetyl-acetonate complexes of vanadium (4) and (3) takes place. At that the solvent is oxidated. In CCl4 solution under the effect of UV irradiation ethoxygroup is replaced by chlorine ion with the formation of new mixed vanadium (5) complex, sensible to visible and UV radiation

  17. Stress induced reorientation of vanadium hydride

    Beardsley, M. B.

    1977-10-01

    The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180/sup 0/ to 280/sup 0/K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch.

  18. Assessment of vanadium sorption by different soils.

    Hadialhejazi, Golshid

    2012-01-01

    Vanadium is a white bright metal that belongs to group 5 in the periodic table of elements. It can exist in different oxidation states from -2 to +5 although the forms can be found naturally in the environment are (III), (IV) and (V). As vanadium is toxic at high concentrations, and as vanadium is a common contaminant from e.g., steel slags, more detailed knowledge on the environmental behavior of this metal is required. One important property is its sorption to soils, as this will determine ...

  19. Study of vanadium complex with pyrocatechol violet and 1.10-phenanthroline in aqueous and organic media

    Spectrophotometrically it has been established that in an aqueous phase in the system of vanadium-pyrocatechol violet (PV)-phenanthroline (Phen) two complexes are formed with the V:PV:Phen ratio equal to 1:1:1 and 1:2:2. The complex with the ration of 1:2:2 is extracted with n-butyl alcohol. Extraction constant of the complex is 8x107. Nolar extinction coefficient of the complex is 1.72x104 (n-butyl alcohol) and 1.39x104 (water). An extraction-photometric method has been developed for determining vanadium in binary aluminium-vanadium alloys with the content of the components of 10 to 90 at.% without preliminary separation of aluminium

  20. Effect of vanadium addition on the microstructure and mechanical properties of the ODS ferritic steels

    In this work, the effects of vanadium addition in the range of 0.3–3% (in weight percent) for an oxide dispersion strengthened reduced activation ferritic (ODS RAF) steel were investigated. Samples of the V-modified steel have been prepared using elemental (Fe, Cr, W, Ti) and Y2O3 powders with the nominal composition of Fe–14Cr–2W–0.3Ti–0.3Y2O3. Consolidated and heat treated samples were investigated using Scanning Electron Microscopy and Scanning Transmission Electron Microscopy equipped with Electron Energy Loss Spectroscopy detector. Hardness and Charpy impact tests (KLST specimens) were also performed. The microstructure investigations revealed numerous particles of the size up to 0.5 μm. They are primarily Ti–Cr–V oxides located at the grain boundaries and inside the grains. These particles increase hardness and significantly reduce fracture resistance of the ODS RAF alloys developed here. However, it should be noted that the 0.3% V-ODS steel has unexpectedly the lowest transition temperature of about 282 K and that the 1–3% V-ODS steels, in spite of the transition temperature about 373 K, exhibit almost two times higher the lower shelf energy values in comparison with the 0.3% V-ODS and 0% V-ODS steels

  1. Highly branched PtCu bimetallic alloy nanodendrites with superior electrocatalytic activities for oxygen reduction reactions

    Fu, Shaofang; Zhu, Chengzhou; Shi, Qiurong; Xia, Haibing; Du, Dan; Lin, Yuehe

    2016-02-01

    Morphology control is a promising strategy to improve the catalytic performance of Pt-based catalysts. In this work, we reported a facile synthesis of PtCu bimetallic alloy nanodendrites using Brij 58 as a template. The highly branched structures and porous features offer relatively large surface areas, which is beneficial to the enhancement of the catalytic activity for oxygen reduction reactions in fuel cells. In addition, the elimination of carbon supports showed an important effect on the stability of the catalysts. By tuning the ratio of Pt and Cu precursors, PtCu nanodendrites were almost four times more active on the basis of an equivalent Pt mass for oxygen reduction reactions than the commercial Pt/C catalyst.Morphology control is a promising strategy to improve the catalytic performance of Pt-based catalysts. In this work, we reported a facile synthesis of PtCu bimetallic alloy nanodendrites using Brij 58 as a template. The highly branched structures and porous features offer relatively large surface areas, which is beneficial to the enhancement of the catalytic activity for oxygen reduction reactions in fuel cells. In addition, the elimination of carbon supports showed an important effect on the stability of the catalysts. By tuning the ratio of Pt and Cu precursors, PtCu nanodendrites were almost four times more active on the basis of an equivalent Pt mass for oxygen reduction reactions than the commercial Pt/C catalyst. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07682j

  2. Shape memory alloy-based biopsy device for active locomotive intestinal capsule endoscope.

    Le, Viet Ha; Hernando, Leon-Rodriguez; Lee, Cheong; Choi, Hyunchul; Jin, Zhen; Nguyen, Kim Tien; Go, Gwangjun; Ko, Seong-Young; Park, Jong-Oh; Park, Sukho

    2015-03-01

    Recently, capsule endoscopes have been used for diagnosis in digestive organs. However, because a capsule endoscope does not have a locomotive function, its use has been limited to small tubular digestive organs, such as small intestine and esophagus. To address this problem, researchers have begun studying an active locomotive intestine capsule endoscope as a medical instrument for the whole gastrointestinal tract. We have developed a capsule endoscope with a small permanent magnet that is actuated by an electromagnetic actuation system, allowing active and flexible movement in the patient's gut environment. In addition, researchers have noted the need for a biopsy function in capsule endoscope for the definitive diagnosis of digestive diseases. Therefore, this paper proposes a novel robotic biopsy device for active locomotive intestine capsule endoscope. The proposed biopsy device has a sharp blade connected with a shape memory alloy actuator. The biopsy device measuring 12 mm in diameter and 3 mm in length was integrated into our capsule endoscope prototype, where the device's sharp blade was activated and exposed by the shape memory alloy actuator. Then the electromagnetic actuation system generated a specific motion of the capsule endoscope to extract the tissue sample from the intestines. The final biopsy sample tissue had a volume of about 6 mm(3), which is a sufficient amount for a histological analysis. Consequently, we proposed the working principle of the biopsy device and conducted an in-vitro biopsy test to verify the feasibility of the biopsy device integrated into the capsule endoscope prototype using the electro-magnetic actuation system. PMID:25834001

  3. Novel vanadium phosphate phases as catalysts for selective oxidation

    Arunabha Datta; Monika Agarwal; Soumen Dasgupta

    2002-08-01

    In our effort to induce novel modifications in the structure of some important vanadium phosphate phases used as selective oxidation catalysts, it has been observed that metal ions such as Zn2+, Ni2+, Pd2+ can be incorporated into the vanadyl hydrogen phosphate VOHPO4$\\cdot$0.5H2O phase in very different ways depending upon the medium of preparation. It has been found that the metal ions are either substituted into the lattice with retention of structure of the parent compound or intercalated between the layers of a new mixed-valent phase. These new metalincorporated phases are catalytically active and the palladium incorporated compound in particular displays shape selective catalysis for different oxidation and reduction reactions. In another approach, the preparation of VOHPO4$\\cdot$0.5H2O has been modified to give a novel crystalline phase containing mixed-valent vanadium and having NH3 species bound to the lattice. This phase could be a potential catalyst for ammoxidation reactions. In addition, novel mesostructured vanadium phosphate phases have been prepared using a long-chain amine as the templating agent involving a ligand templating mechanism of formation.

  4. Effect of organic additives on positive electrolyte for vanadium redox battery

    Li Sha [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: lisha_csu@163.com [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2011-06-30

    Highlights: > Four organics as electrolyte additives of vanadium redox battery. > Changes are examined in the electrochemical properties of vanadium redox battery. > D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. > The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO{sup 2+} ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  5. Effect of organic additives on positive electrolyte for vanadium redox battery

    Highlights: → Four organics as electrolyte additives of vanadium redox battery. → Changes are examined in the electrochemical properties of vanadium redox battery. → D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. → The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO2+ ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  6. Determination of the oxidation state and coordination of a vanadium doped chalcogenide glass

    Hughes, Mark A.; Curry, Richard J.; Hewak, Daniel W.

    2011-01-01

    Vanadium doped chalcogenide glass has potential as an active gain medium, particularly at telecommunications wavelengths. This dopant has three spin allowed absorption transitions at 1100, 737 and 578 nm, and a spin forbidden absorption transition at 1000 nm. X-ray photoelectron spectroscopy indicated the presence of vanadium in a range of oxidation states from V+ to V5+. Excitation of each absorption band resulted in the same characteristic emission spectrum and lifetime, indicating that only one oxidation state is optically active. Arguments based on Tanabe-Sugano analysis indicated that the configuration of the optically active vanadium ion was octahedral V2+. The calculated crystal field parameters (Dq/B, B and C/B) were 1.85, 485.1 and 4.55, respectively.

  7. Deformation of vanadium and niobium on hydridation

    Deformation of wire samples made of polycrystalline vanadium and niobium on hydridation is studied. It is shown that sample allowance under loading after deformation below the yield strength doesn't cause considerable creep. Cathode saturation of samples with hydrogen sharply accelerates vanadium microdeformation velocity, that is connected with the beginning of intensive vanadium hydride precipitation (β-phase) from α-solid vanadium-hydrogen solution. Niobium hydridation at the first stage doesn't hydridation at the first stage doesn't cause negative deformation, then change in deformation direction takes place at the moment of intensive growth of the hydride phase. The conclusion is made that in both metals microdeformation is determined by contribution of two components: deformation caused by changing a shift module of metal-hydrogen system, and deformation caused by the oriented growth of the hydride phase in the field of apphed stresses

  8. Synthesis, characterization and crystal structure determination of a new vanadium(IV) Schiff base complex (VOL.sub.2./sub.) and investigation of its catalytic activity in the epoxidation of cyclooctene

    Grivani, G.; Tahmasebi, V.; Khalaji, A.D.; Fejfarová, Karla; Dušek, Michal

    2013-01-01

    Roč. 51, č. 1 (2013), s. 54-60. ISSN 0277-5387 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : vanadium (IV) * Schiff base * single crystal * structure determination * catalysis * epoxidation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.047, year: 2013

  9. An universal formula for the calculation of nitrogen solubility in liquid nitrogen-alloyed steels

    J. Siwka

    2009-01-01

    Full Text Available The results of the authors’ own experimental studies on the Fe - N system, its standard state, binary alloys of iron with chromium, molybdenum, manganese, nickel, vanadium, silicon and carbon, as well as ternary alloys with chromium, have made it possible to work out the whole required complex of parameters of nitrogen interaction in liquid iron alloys, including the self-interaction parameters of nitrogen-nitrogen and nitrogen-alloying elements.

  10. An universal formula for the calculation of nitrogen solubility in liquid nitrogen-alloyed steels

    J. Siwka; A. Hutny

    2009-01-01

    The results of the authors’ own experimental studies on the Fe - N system, its standard state, binary alloys of iron with chromium, molybdenum, manganese, nickel, vanadium, silicon and carbon, as well as ternary alloys with chromium, have made it possible to work out the whole required complex of parameters of nitrogen interaction in liquid iron alloys, including the self-interaction parameters of nitrogen-nitrogen and nitrogen-alloying elements.

  11. High-strength low-alloy (HSLA) steels: Visokotrdna malolegirana (HSLA) konstrukcijska jekla:

    Skobir Balantič, Danijela Anica

    2011-01-01

    Micro-alloyed, high-strength, low-alloy (HSLA) steels are important structural materials and contain small amounts of alloying elements, such as niobium, titanium, vanadium, and aluminium, which enhance the strength through the formation of stable carbides, nitrides or carbonitrides and have an effect on the hardenability. Such steels contain less than 0.1 % of the alloying additions, used individually or in combination. Yield strength increments of two or three times that of plain carbon-man...

  12. Synthesis and anti-bacterial activity of Cu, Ag and Cu-Ag alloy nanoparticles: A green approach

    Research highlights: → Synthesis of novel nanosized copper-silver alloys of different compositions. → Completely green approach for synthesis of water soluble bimetallic nanoparticle. → Interesting anti-bacterial activity of as synthesized metal and alloy nanoparticle. -- Abstract: Metallic and bimetallic nanoparticles of copper and silver in various proportions were prepared by microwave assisted chemical reduction in aqueous medium using the biopolymer, starch as a stabilizing agent. Ascorbic acid was used as the reducing agent. The silver and copper nanoparticles exhibited surface plasmon absorption resonance maxima (SPR) at 416 and 584 nm, respectively; while SPR for the Cu-Ag alloys appeared in between depending on the alloy composition. The SPR maxima for bimetallic nanoparticles changes linearly with increasing copper content in the alloy. Transmission electron micrograph (TEM) showed monodispersed particles in the range of 20 ± 5 nm size. Both silver and copper nanoparticles exhibited emission band at 485 and 645 nm, respectively. The starch-stabilized nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micromolar concentrations.

  13. Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

  14. The ability of silicide coating to delay the catastrophic oxidation of vanadium under severe conditions

    Chaia, N.; Mathieu, S.; Rouillard, F.; Vilasi, M.

    2015-02-01

    V-4Cr-4Ti vanadium alloy is a potential cladding material for sodium-cooled fast-neutron reactors (SFRs). However, its affinity for oxygen and the subsequent embrittlement that oxygen induces causes a need for an oxygen diffusion barrier, which can be obtained by manufacturing a multi-layered silicide coating. The present work aims to evaluate the effects of thermal cycling (using a cyclic oxidation device) and tensile and compressive stresses (using the three-point flexure test) on the coated alloy system. Tests were performed in air up to 1100 °C, which is 200 °C higher than the accidental temperature for SFR applications. The results showed that the VSi2 coating was able to protect the vanadium substrate from oxidation for more than 400 1-h cycles between 1100 °C and room temperature. The severe bending applied to the coated alloy at 950 °C using a load of 75 MPa did not lead to specimen breakage. It can be suggested that the VSi2 coating has mechanical properties compatible with the V-4Cr-4Ti alloy for SFR applications.

  15. Transformation and precipitation in vanadium treated steels

    Vassiliou, Andreas Demetriou

    1987-01-01

    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 fer...

  16. Investigation of vanadium (4) monooximates in solution

    It is shown that vanadium (4) forms the complex compounds with some n-substituted compounds of benzaldoxime: n-dimethylaminobenzaldoxime, n-diethylaminobenzaldoxime, n-methoxybenzaldoxime (anise oxime). The electron spectra of the compounds are studied; the reference of the bands is conducted. The stability constants of vanadium monooximates are calculated. The principle possibility of use of the complexing reaction use between the V(4) and the monooximates for analytical purposes is shown

  17. The role of vanadium in biology.

    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. PMID:25608665

  18. Hybrid uranyl-vanadium nano-wheels.

    Senchyk, G A; Wylie, E M; Prizio, S; Szymanowski, J E S; Sigmon, G E; Burns, P C

    2015-06-25

    Hybrid uranyl-vanadium oxide clusters intermediate between transition metal polyoxometalates and uranyl peroxide cage clusters were obtained by dissolving uranyl nitrate in the ionic liquid 3-ethyl-1-methylimidazolium ethyl sulfate mixed with an aqueous solution containing vanadium. Where sulfate was present, wheel-shaped {U20V20} crystallized and contains ten sulfate tetrahedra, and in the absence of added sulfate, {U2V16}, a derivative of {V18}, was obtained. PMID:26008125

  19. Effect of vanadium on colonic aberrant crypt foci induced in rats by 1,2 Dimethyl hydrazine

    P Suresh Kanna; CB Mahendrakumar; T Chakraborty; P Hemalatha; Pratik Banerjee; M Chatterjee

    2003-01-01

    AIM: To investigate the chemo preventive effects of vanadium on rat colorectal carcinogenesis induced by 1,2-dimethylhydrazine (DMH).METHODS: Male Sprague-Dawley Rats were randomly divided into four groups. Rats in Group A received saline vehicle alone for 16 weeks. Rats in Group B were given DMH injection once a week intraperitoneally for 16 weeks;rats in Group C, with the same DMH treatment as in the Group B, but received 0.5-ppm vanadium in the form ammonium monovanadate ad libitum in drinking water. Rats in the Group D received vanadium alone as in the Group C without DMH injection.RESULTS: Aberrant crypt foci (ACF) were formed in animals in DMH-treated groups at the end of week 16.Compared to DMH group, vanadium treated group had less ACF (P<0.001). At the end of week 32, all rats in DMH group developed large intestinal tumors. Rats treated with vanadium contained significantly few colonic adenomas and carcinomas (P<0.05) compared to rats administered DMH only. In addition, a significant reduction (P<0.05) in colon tumor burden (sum of tumor sizes per animal) was also evident in animals of Group C when compared to those in rats of carcinogen control Group B. The results also showed that vanadium significantly lowered PCNA index in ACF (P<0.005). Furthermore, vanadium supplementation also elevated liver GST and Cyt P-450 activities (P<0.001 and P<0.02, respectively).CONCLUSION: Vanadium in the form of ammonium monovanadate supplemented in drinking water ad libitum has been found to be highly effective in reducing tumor incidence and preneoplastic foci on DMH-induced colorectal carcinogenesis. These findings suggest that vanadium administration can suppress colon carcinogenesis in rats.

  20. Vanadium(IV/V) complexes of Triapine and related thiosemicarbazones: Synthesis, solution equilibrium and bioactivity.

    Kowol, Christian R; Nagy, Nóra V; Jakusch, Tamás; Roller, Alexander; Heffeter, Petra; Keppler, Bernhard K; Enyedy, Éva A

    2015-11-01

    The stoichiometry and thermodynamic stability of vanadium(IV/V) complexes of Triapine and two related α(N)-heterocyclic thiosemicarbazones (TSCs) with potential antitumor activity have been determined by pH-potentiometry, EPR and (51)V NMR spectroscopy in 30% (w/w) dimethyl sulfoxide/water solvent mixtures. In all cases, mono-ligand complexes in different protonation states were identified. Dimethylation of the terminal amino group resulted in the formation of vanadium(IV/V) complexes with considerably higher stability. Three of the most stable complexes were also synthesized in solid state and comprehensively characterized. The biological evaluation of the synthesized vanadium complexes in comparison to the metal-free ligands in different human cancer cell lines revealed only minimal influence of the metal ion. Thus, in addition the coordination ability of salicylaldehyde thiosemicarbazone (STSC) to vanadium(IV/V) ions was investigated. The exchange of the pyridine nitrogen of the α(N)-heterocyclic TSCs to a phenolate oxygen in STSC significantly increased the stability of the complexes in solution. Finally, this also resulted in increased cytotoxicity activity of a vanadium(V) complex of STSC compared to the metal-free ligand. PMID:26349014

  1. Activation Energy Measurement of Oxygen Ordering in a Nb-Ti Alloy by Anelastic Relaxation

    Niemeyer T.C.

    2002-01-01

    Full Text Available Metals with bcc structure are able to dissolve large amounts of interstitial element atoms in the form of oxygen. These atoms diffuse through the lattice by jumping into octahedral sites with equivalent symmetry, causing strong alterations in the anelastic behavior. This paper reports on a study of Snoek relaxation in Nb-Ti alloys with oxygen in solid solution, based on internal friction as a function of temperature. The internal friction measurements were taken in a torsion pendulum operating at temperatures in the range of 350 to 650 K, with frequencies varying from 6 to 36 Hz. The results show relaxation spectra in which thermally activated relaxation peaks produced by the stress-induced ordering of oxygen atoms around niobium atoms of the metallic matrix were identified.

  2. First principles investigation of the activity of thin film Pt, Pd and Au surface alloys for oxygen reduction

    Tripkovic, Vladimir; Hansen, Heine Anton; Rossmeisl, Jan;

    2015-01-01

    of Au with mixed Pt/Pd skins. The activity of the binary and ternary catalysts is explained through weakening of the OH binding energy caused by solute elements. However, given the low alloy formation energies it may be difficult to tune and retain the composition under operating conditions. This is...

  3. Reaction of oxalic and sulfuric acids with vanadium in spent sulfuric-acid vanadium catalysts

    The effect of oxalic acid on the degree of extraction of vanadium from spent sulfuric acid catalysts is studied. It is shown that soluble vanadium oxalate complexes are formed in the presence of sulfuric acid both in aqueous solution and in a mixture of solid components

  4. Vanadium recovery from clay vanadium mineral using an acid leaching method

    LI Haoran; FENG Yali; LIANG Jianglong; LUO Xiaobing; DU Zhuwei

    2008-01-01

    A technique including direct acid leaching,vanadium precipitation with alkaline,sodium hydroxide releaching,impurity removing by adjusting pH value,precipitation vanadium with ammonium chloride,and vanadium pentoxide by roasting steps was proposed according to the characteristic of Xichuan clay vanadium mineral.The factors influencing leaching vanadium such as temperature and the concentration of sulfuric acid were investigated and optimized.The experimental results indicate that the extract ratios of V2O5 can reach 94% and 92% at a sodium chlorate ratio of 3% and a manganese dioxide ratio of 3%,respectively.A completely chemical precipitation method was adopted to decontaminate and enrich the vanadium in the acid leaching solution.The X-ray diffraction (XRD) pattern and the purity analysis of vanadium pentoxide indicate that the purity of final vanadium pentoxide can reach 99% and meet the standard specifications.The total recovery can reach about 75%.The technique has the characteristics of simplicity,less investlnent,and more environment safety as compared with the traditional salt roasting method.

  5. Activation energy analysis of secondary phase precipitate In Zr-%Nb-1%Sn-1%Fe alloy

    The objective of this research is to analyze of activation energies in Zr-1%Nb-1%Sn-1%Fe alloy as the product of the synthesis. The ingot was prepared by single spark melting. The samples then anneal at temperature 400°C, 500°C, 600°C, 700°C dan 800°C for 2 hours. The analyzed was focused on secondary phase precipitate/ SPP. The activation energies was identified based on X-rays diffraction pattern and supported by Joint Committee Powder Diffraction File/ JCPDF. The Result of diffraction pattern with the data were analyzed by manual, it was not done by direct meet with the JCPDF data because of the distortion of the SPP. The analyzed results were concluded as follow: The nucleation of the secondary phase precipitate/ SPP was good at the anneal temperature of 400°C, 500°C, and 700°C. The Zr-1%Nb-1%Sn-1%Fe alloy at temperature in between 400°C to 800°C were found the precipitates Fe2Nb, ZrSn2,FeSn, SnZr, NbSn2, Zr0.68Nb0.25Fe0.08, Fe2Nb0.4Zr0.6, Fe37Nb9Zr54, and ω-Zr. At temperature anneal 800°C was good for the precipitate stabilization, at temperature in between 500°C to 600°C was good for the precipitate growth, at temperature anneal 700°C was good for minimizing the precipitate size. It was found that activation energy of Fe2Nb was -7,0083 kJ/mol, activation energy of FeSn was -2,2858 kJ/mol, activation energy of NbSn2 was -3,1498 kJ/mol and activation energy of α-Zr nano crystallite was 0,0077 kJ/mol. (author)

  6. Neutron activation studies of the in-body corrosion of hip-joint prostheses made of Co-Cr alloys

    Using instrumental neutron activation analysis (INAA) the trace element composition of 18 elements was investigated in human tissues (articular capsule and fascia lata) of 36 persons after removal of hip-joint prostheses made of Co-Cr alloys. Normal trace element concentrations were determined studying a group of 26 patients before receiving their first artificial hip-joint. The tissues of patients with metal implants exhibited a heavy burdening by corrosion products (Co, Cr, Ni) from the prostheses as well as by Zr, Hf and Ba from the bone cements. Moreover, changes in the distribution of trace elements not contained in the steel were also observed. A comparison of the analytical results with those of model experiments of the corrosion of Co-Cr alloy in Ringer's solution demonstrates that the distribution pattern of corrosion products in the tissues are influenced by both, the biochemical properties as well as by selective dissolution of the alloy constituents. (author)

  7. Titanium-Nickel Shape Memory Alloy Spring Actuator for Forward-Looking Active Catheter

    Takahiro Namazu

    2011-01-01

    Full Text Available The fabrication and characterization of forward-looking active catheter actuated by titanium-nickel (Ti-Ni shape memory alloy (SMA springs are described. The catheter has been designed for wide-range observation of an affected area inside a blood vessel when the blood vessel is occluded. The developed active catheter consists of eight Ti-Ni SMA spring actuators for actuation of catheter tip, an ultrasonic transducer for forward-looking, a guide wire, a polyurethane tube for coating, and spiral wirings for realization of various flexure motions of catheter tip using Ti-Ni SMA actuators. The size of the catheter is 3.5 mm in diameter and 60 mm in length of the sum of transducer and actuator sections. Ti-Ni SMA springs were fabricated from a Ti-50.9at.%Ni sheet by electrochemical etching with a mixed solution of ethanol and lithium chloride. The catheter was assembled by hand under a stereomicroscope. The tip of the produced catheter was able to move in parallel toward at least eight directions by controlling an applied current to Ti-Ni SMA springs. We have confirmed that the active catheter was able to observe an object settled in the front.

  8. Design optimization study of a shape memory alloy active needle for biomedical applications.

    Konh, Bardia; Honarvar, Mohammad; Hutapea, Parsaoran

    2015-05-01

    Majority of cancer interventions today are performed percutaneously using needle-based procedures, i.e. through the skin and soft tissue. The difficulty in most of these procedures is to attain a precise navigation through tissue reaching target locations. To overcome this challenge, active needles have been proposed recently where actuation forces from shape memory alloys (SMAs) are utilized to assist the maneuverability and accuracy of surgical needles. In the first part of this study, actuation capability of SMA wires was studied. The complex response of SMAs was investigated via a MATLAB implementation of the Brinson model and verified via experimental tests. The isothermal stress-strain curves of SMAs were simulated and defined as a material model in finite element analysis (FEA). The FEA was validated experimentally with developed prototypes. In the second part of this study, the active needle design was optimized using genetic algorithm aiming its maximum flexibility. Design parameters influencing the steerability include the needle's diameter, wire diameter, pre-strain and its offset from the needle. A simplified model was presented to decrease the computation time in iterative analyses. Integration of the SMA characteristics with the automated optimization schemes described in this study led to an improved design of the active needle. PMID:25782329

  9. Crystallization of Low-alloyed Construction Cast Steel Modified with V and Ti

    A. Studnicki

    2013-07-01

    Full Text Available In this paper crystallization studies of low-alloyed construction cast steel were presented for different additions of chromium, nickel and molybdenum modified with vanadium and titanium. Studies were conducted using developed TDA stand, which additionally enabled evaluation of cooling rate influence on crystallization process of investigated alloys.

  10. Colour and colour contrast of films based on vanadium oxide

    Results of studying thin vanadium oxide films having thermochromic effect are presented. For quantitative estimation of colour variation in vanadium-oxide layers at phase transformations, CTELAB equicontrast system is used. The films were applied by vacuum deposition of metallic vanadium and them were subject to controlled oxidation in oxygen. It is shown that it is possible to create dynamic standards of colour on the basis of vanadium oxides

  11. Chemical conversion coating for protecting magnesium alloys from corrosion

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh; Hornish, Peter; Jain, Mohit

    2016-01-05

    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 as self-healing moieties to defect sites, thus providing active corrosion protection.

  12. Investigation of the electrospun carbon web as the catalyst layer for vanadium redox flow battery

    Wei, Guanjie; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei

    2014-12-01

    Polyacrylonitrile (PAN) carbon nonwoven web consisting of 100-200 nm ultrafine fibers has been developed by electrospinning and subsequent carbonization process at 1000 °C for different times. The surface morphology, composition, structure, and electrical conductivity of the electrospun carbon webs (ECWs) as well as their electrochemical properties toward vanadium redox couples have been characterized. With the increasing of carbonization time, the electrochemical reversibility of the vanadium redox couples on the ECW is enhanced greatly. As the carbonization time increases up to 120 min, the hydrogen evolution is facilitated while the reversibility is promoted a little bit further. The excellent performance of ECW may be attributed to the conversion of fibers carbon structure and improvement of electrical conductivity. Due to the good electrochemical activity and freestanding 3-dimensional structure, the ECW carbonized for 90 min is used as catalyst layer in vanadium redox flow battery (VRFB) and enhances the cell performance.

  13. Vanadium(5) peroxocomplexes in catalysis of hydrogen peroxide transformations in trifluoroacetic acid

    It is found that vanadium(5) complexes in trifluoroacetic acid catalyze effectively hydrogen peroxide decomposition with formation of considerable amounts of ozone (up to 15 %). It is also found that vanadium compounds in the course of interaction with peroxytrifluoroacetic acid catalyze not only its decomposition but also decarboxylation. It is ascertained by kinetic methods that in the system V(5)-H2O2-CF3COOH a series of vanadium(5) active complexes, responsible for oxidation of all the compounds studied and ozone evolution, are formed. It is shown that in the formation of the compounds both hydrogen peroxide and peroxytrifluoroacetic acid take part. All the regularities found are explained in the framework of the model, involving intrasphere regrouping of two peroxoligands into grouping (O32-). A mathematical model, which gives an adequate description of substrate oxidation and ozone formation, is plotted

  14. Electrorheological properties of polyaniline-vanadium oxide nanostructures suspended in silicone oil

    Goswami, Sumita; Brehm, Tiago; Filonovich, Sergej; Cidade, Maria Teresa

    2014-10-01

    In the present work, organic/inorganic hybrid nanostructures comprised of polyaniline and vanadium oxide were synthesized via a simple hydrothermal technique. The polyaniline/vanadium oxide hybrid morphology was tailored from rods to spheres by controlling the relative concentration of the reactants. The synthesized composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) for structural and morphological analyses. Electrorheological (ER) properties of the as-prepared nanocomposites suspended in silicone oil were investigated by a rotational viscometer under both steady and dynamic shear. The ER activity of the composite material suspensions showed higher ER effects for the product with the rod-like structures than for the product with the sphere-like structures. The typical ER behaviour showed by the polyaniline-vanadium oxide nanocomposites demonstrated their potential application as an ER smart material.

  15. A coupled-physics model for the vanadium oxygen fuel cell

    Wandschneider, F. T.; Küttinger, M.; Noack, J.; Fischer, P.; Pinkwart, K.; Tübke, J.; Nirschl, H.

    2014-08-01

    A stationary two-dimensional model for the vanadium oxygen fuel cell is developed. The model consists of a single cell with two membranes, set up as of two half-cells and an intermediate chamber. The transport and balance of mass, momentum and charge are linked to the electrochemical reaction kinetics of the vanadium species and oxygen. The kinetic model for the cathode half-cell is extended by an empirical logistic function to describe the transient behavior of the half-cell. Additionally, experiments are conducted on a single vanadium oxygen fuel cell with 40 cm2 active membrane area. The experimental results are used to validate the simulation data. The effects of constant current discharging, polarization behavior and different flow rates on the cathode overpotential are studied by means of this model.

  16. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

    Oluwabusayo Folarin

    2016-01-01

    Full Text Available 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.

  17. Asymmetric epoxidation of allylic alcohols catalyzed by vanadium-binaphthylbishydroxamic Acid complex.

    Noji, Masahiro; Kobayashi, Toshihiro; Uechi, Yuria; Kikuchi, Asami; Kondo, Hisako; Sugiyama, Shigeo; Ishii, Keitaro

    2015-03-20

    A vanadium-binaphthylbishydroxamic acid (BBHA) complex-catalyzed asymmetric epoxidation of allylic alcohols is described. The optically active binaphthyl-based ligands BBHA 2a and 2b were synthesized from (S)-1,1'-binaphthyl-2,2'-dicarboxylic acid and N-substituted-O-trimethylsilyl (TMS)-protected hydroxylamines via a one-pot, three-step procedure. The epoxidations of 2,3,3-trisubstituted allylic alcohols using the vanadium complex of 2a were easily performed in toluene with a TBHP water solution to afford (2R)-epoxy alcohols in good to excellent enantioselectivities. PMID:25714329

  18. Kinetics and interface phenomena during vanadium extraction by tri-n-octylamine

    Vanadium (5) solvent extraction by tri-n-octyl amine (toa) solution in kerosene in the presence of isododecyl alcohol is studied using the methods of short-time phase contacting and diffusion cell with agitation together with the interface tension measuring. Vanadium (5) extraction by toa is accompanied by the formation of structure-mechanical barrier, connected with accumulation of by-products and forming polymeric films. The process is described by the equation of irreversible chemical reaction of the first order according to diffusing substance. Activation energy is 50,07 kJ/mol. 2 refs.; 5 figs

  19. Thermal desorption of oxygen from near-stoichiometric cationic vanadium oxide clusters

    Kurokawa, Hodaka; Mafuné, Fumitaka

    2016-05-01

    Oxygen desorption from cationic vanadium oxide clusters, VnOm+ (n = 2-10), composed of a near-stoichiometric (n:m = 2:5) frame with excess oxygen attached was investigated in a thermal energy region by time-of-flight mass spectrometry and thermal desorption spectrometry. Oxygen molecules were observed to desorb from the clusters during heating. The activation energy for desorption was estimated from the temperature dependence of different clusters and exhibited an even-odd alternation with respect to the cluster size, n. This alternation can be explained in terms of oxidation states of the vanadium atoms.

  20. Reactivity-activity relationships of oral anti-diabetic vanadium complexes in gastrointestinal media: an X-ray absorption spectroscopic study.

    Levina, Aviva; McLeod, Andrew I; Kremer, Lauren E; Aitken, Jade B; Glover, Christopher J; Johannessen, Bernt; Lay, Peter A

    2014-10-01

    The reactions of oral V(V/IV) anti-diabetic drugs within the gastrointestinal environment (particularly in the presence of food) are a crucial factor that affects their biological activities, but to date these have been poorly understood. In order to build up reactivity-activity relationships, the first detailed study of the reactivities of typical V-based anti-diabetics, Na3V(V)O4 (A), [V(IV)O(OH2)5](SO4) (B), [V(IV)O(ma)2] (C, ma = maltolato(-)) and (NH4)[V(V)(O)2(dipic)] (D, dipic = pyridine-2,5-dicarboxylato(2-)) with simulated gastrointestinal (GI) media in the presence or absence of food components has been performed by the use of XANES (X-ray absorption near edge structure) spectroscopy. Changes in speciation under conditions that simulate interactions in the GI tract have been discerned using correlations of XANES parameters that were based on a library of model V(V), V(IV), and V(III) complexes for preliminary assessment of the oxidation states and coordination numbers. More detailed speciation analyses were performed using multiple linear regression fits of XANES from the model complexes to XANES obtained from the reaction products from interactions with the GI media. Compounds B and D were relatively stable in the gastric environment (pH ∼ 2) in the absence of food, while C was mostly dissociated, and A was converted to [V10O28](6-). Sequential gastric and intestinal digestion in the absence of food converted A, B and D to poorly absorbed tetrahedral vanadates, while C formed five- or six-coordinate V(V) species where the maltolato ligands were likely to be partially retained. XANES obtained from gastric digestion of A-D in the presence of typical food components converged to that of a mixture of V(IV)-aqua, V(IV)-amino acid and V(III)-aqua complexes. Subsequent intestinal digestion led predominantly to V(IV) complexes that were assigned as citrato or complexes with 2-hydroxyacidato donor groups from other organic compounds, including certain

  1. Synthesis of vanadium-phosphorus oxide systems by joint chemisorption of phosphorus and vanadium oxychlorides on silica surface

    A new method of synthesis on silica of multilayer vanadium-phosphorus oxide systems containing vanadium in oxidation state (+4), which consists in joint chemisorption of phosphorus and vanadium oxychlorides, hydrolysis of surface chlorine-containing compounds by water steam and vanadium reduction by ammonia vapors, was suggested. The samples prepared were characterized by the method of ESR, IR spectroscopy and electron spectroscopy of diffuse reflection

  2. Study of surface modification of alloys by photoelectron spectroscopy and neutron activation analysis: application to the study of a gold-copper alloy

    Ion erosion etching is generally used to prepare surfaces for electron spectroscopy (ESCA and AES). During etching, selective interactions occur between ions and various elements from which the solid is constituted. The surface studied therefore undergoes modifications. Modifications of this type in the surface of a gold-copper alloy have been studied. The characteristics of an ion beam generated by a commercial gun without sweeping have been determined for low energy ions (beam shape, ion density distribution). These characteristics are then related to the effects observed (crater shape, etching rate). Neutron activation analysis has been used to determine the quantity of sputtered matter and subsequently the sputtering rate. Finally, a sequential analysis of sputtered matter (activation analysis) and studies of the characteristics of the eroded surface have confirmed the existence of a transient regime and enabled a correlation to be etablished between the composition of the surface layer for a stationary regime and the model used to describe the sputtering

  3. In vivo degradation behavior and biological activity of some new Mg-Ca alloys with concentration's gradient of Si for bone grafts

    Trincă, Lucia Carmen; Fântânariu, Mircea; Solcan, Carmen; Trofin, Alina Elena; Burtan, Liviu; Acatrinei, Dumitru Mihai; Stanciu, Sergiu; Istrate, Bogdan; Munteanu, Corneliu

    2015-10-01

    Magnesium based alloys, especially Mg-Ca alloys, are biocompatible substrates with mechanical properties similar to those of bones. The biodegradable alloys of Mg-Ca provide sufficient mechanical strength in load carrying applications as opposed to biopolymers and also they avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. The main issue facing a biodegradable Mg-Ca alloy is the fast degradation in the aggressive physiological environment of the body. The alloy's corrosion is proportional with the dissolution of the Mg in the body: the reaction with the water generates magnesium hydroxide and hydrogen. The accelerated corrosion will lead to early loss of the alloy's mechanical integrity. The degradation rate of an alloy can be improved mainly through tailoring the composition and by carrying out surface treatments. This research focuses on the ability to adjust degradation rate of Mg-Ca alloys by an original method and studies the biological activity of the resulted specimens. A new Mg-Ca alloy, with a Si gradient concentration from the surface to the interior of the material, was obtained. The surface morphology was investigated using scanning electron microscopy (VegaTescan LMH II, SE detector, 30 kV), X-ray diffraction (X'Pert equipment) and energy dispersive X-ray (Bruker EDS equipment). In vivo degradation behavior, biological compatibility and activity of Mg-Ca alloys with/without Si gradient concentration were studied with an implant model (subcutaneous and bony) in rats. The organism response to implants was characterized by using radiological (plain X-rays and computed tomography), biochemical and histological methods of investigation. The results sustained that Si gradient concentration can be used to control the rate of degradation of the Mg-Ca alloys for enhancing their biologic activity in order to facilitate bone tissue repair.

  4. Determination of trace amounts of cadmium, cobalt, chromium, iron, molybdenum, nickel, selenium, titanium, vanadium and zinc in blood and milk by neutron activation analysis

    The concentrations of Cd, Co, Cr, Fe, Mo, Ni, Se, Ti, V and Zn in biological fluids, human blood serum and market milk were determined by neutron activation analysis, with enrichment by coprecipitation. The pre-concentration of these trace elements was accomplished by converting the dissolved trace metal ions into their pyrrolidinedithiocarbamate (1-pyrrolidinecarbodithioate) chelates, followed by coprecipitation with a metal carrier such as Ni, Pb or Bi. The coprecipitation was carried out prior to irradiation for the short-lived nuclides (V, Ti and Se) and after irradiation for the other elements. The validity of the method was checked using certified biological reference materials; the concentrations of trace elements found by the proposed method agreed well with the published certified data. The limits of detection for Cd, Co, Cr, Fe, Mo, Ni, Se (obtained through the long-lived isotope 75Se) and Zn under the present experimental conditions were found to be 5, 5, 10, 520, 5, 70, 10 and 150 ng, respectively, for 5 ml of biological liquor. The limits of detection for Ti and V obtained (through their short-lived radionuclides 51Ti and 52V, respectively) were found to be 180 and 1.4 ng, respectively, for 50 ml of market milk, or 70 and 0.7 ng for 1 ml of blood serum. (author)

  5. Interactions of Penicillium griseofulvum with inorganic and organic substrates: vanadium, lead and hexachlorocyclohexane

    Ceci, Andrea; Pierro, Lucia; Riccardi, Carmela; Maggi, Oriana; Pinzari, Flavia; Gadd, Geoffrey Michael; Petrangeli Papini, Marco; Persiani, Anna Maria

    2015-04-01

    Soil is an essential and non-renewable resource for human beings and ecosystems. In recent years, anthropogenic activities mainly related to hydrocarbon fuel combustion, mining and industrial activities have increased the levels of vanadium in the environment, raising concern over its spread. Vanadium may be essential for some bacteria and fungi, but can have toxic effects at high concentrations. The pesticide lindane or γ-hexachlorocyclohexane (γ-HCH) and another two isomers of hexachlorocyclohexane (HCH), α-HCH, and β-HCH, were included as persistent organic pollutants in the Stockholm Convention in 2008, and their worldwide spread and toxic effects on organisms are severe environmental problems. Fungi play important roles in soil and can survive in high concentrations of toxic elements and pesticides by possessing mechanisms for the degradation, utilization and transformation of organic and inorganic substrates. The transformation of potentially toxic elements (PTEs), and degradation of chlorinated pesticides and other persistent organic pollutants may provide environmentally-friendly and economical approaches for environmental management and restoration. In this work, we have investigated the tolerance of a soil fungal species, Penicillum griseofulvum, to different hexachlorocyclohexane (HCH) isomers, α-HCH, β-HCH, δ-HCH and γ-HCH or lindane, and two PTEs, vanadium and lead in relation to growth responses and biotransformation. P. griseofulvum was isolated from soils with high levels of PTEs (including vanadium and lead), and HCH residues. P. griseofulvum was able to tolerate vanadium concentrations up to 5 mM, combinations of 2.5 mM vanadium and lead compounds, and was able to grow in the presence of a 4 mg L-1 mixture of α-HCH, β-HCH, δ-HCH and γ-HCH, and degrade these substrates. Tolerance mechanisms may explain the occurrence of fungi in polluted habitats: their roles in the biotransformation of metals and persistent organic pollutants may

  6. Influence of hydrogen and test temperature on mechanical properties of vanadium and niobium

    The influence of hydrogen on fatigue life of niobium and vanadium is described. In tests carried out under stress control conditions on unnotched material hydrogen extends fatigue life of both metals. However, in stress controlled tests on notched bars and in strain control tests on unnotched bars hydrogen is detrimental to fatigue life. Hydrided alloys are much more sensitive to notches than are the unalloyed metals. Frequency effects on fatigue life also are much more severe in hydrided alloys, lower frequency leading to shorter life. The results of delayed failure, creep tests and elevated temperature fatigue tests also are reported. Niobium and vanadium reveal reduced fatigue lives at elevated temperatures for tests carried out in vacuum. The results of limited hold time and low frequency tests on strain controlled fatigue life also are reported. Increasing hold time increases fatigue life of niobium in the range 450 to 6500C. Fractographic features change from striations in unalloyed metals to cleavage in the hydrided alloys tested at room temperature

  7. Solvents and supporting electrolytes for vanadium acetylacetonate flow batteries

    Shinkle, Aaron A.; Pomaville, Timothy J.; Sleightholme, Alice E. S.; Thompson, Levi T.; Monroe, Charles W.

    2014-02-01

    Properties of supporting electrolytes and solvents were examined for use with vanadium acetylacetonate - a member of the class of metal(β-diketonate) active species - in non-aqueous redox flow batteries. Twenty supporting-electrolyte/solvent combinations were screened for ionic conductivity and supporting-electrolyte solubility. Hexane, tetrahydrofuran, and dimethylcarbonate solvents did not meet minimal conductivity and solubility criteria for any of the electrolytes used, which included tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, and (1-butyl, 3-methyl)imidazolium bis(trifluoromethanesulfonyl)imide. Ionic conductivities and solubilities for solutions of these electrolytes passed screening criteria in acetonitrile and dimethylformamide solvents, in which maximum supporting-electrolyte and active-species solubilities were determined. Active-species electrochemistry was found to be reversible in several solvent/support systems; for some systems the voltammetric signatures of unwanted side reactions were suppressed. Correlations between supporting-solution properties and performance metrics suggest that an optimal solvent for a vanadium acetylacetonate RFB should have a low solvent molar volume for active-species solubility, and a high Hansen polarity for conductivity.

  8. The abrasive wear behaviour of alloy cast steel in SiC-water slurry

    R. Zapała

    2009-10-01

    Full Text Available The results of abrasive wear tests carried out in an environment of SiC-water slurry on four grades of cast steel, i.e. carbon cast steel with microadditions of vanadium, low-alloy L70H2GNM cast steel, and high-alloy L120G13 cast steels, without and with microadditions of vanadium, were discussed. Tests were carried out on a Miller machine. A measure of the abrasive wear resistance was the loss of mass in specimens during 16 hour test cycle. It has been proved that the L120G13 cast steel is definitely less resistant to abrasive wear than its L70H2GNM counterpart. On the other hand, no distinct differences in the abrasive wear resistance were noticed between the L120G13 cast steel without vanadium, and the L120G13 cast steel and carbon cast steel, both with microadditions of vanadium.

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

    Highlights: • The leaching solution contains high concentration of acid, iron, impurities and lower vanadium. • 99.4% of vanadium and 4.2% of iron were extracted by three-stage extraction process. • 99.6% of vanadium and 5.4% of iron were stripped by three-stage stripping process. • The stripping solution contains 40.16 g/L V2O5, 0.691 g/L Fe, 0.007 g/L TiO2 and 0.247 g/L CaO. • The vanadium product of V2O5 with purity of 99.12%, 0.026% Fe and well crystallized. - Abstract: 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 10 min, 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), 20 min 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 40.16 g/L V2O5, 0.691g/L Fe, 0.007 g/L TiO2, 0.006 g/L SiO2 and 0.247 g/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

  10. Bonding of Cf/SiC composite to Invar alloy using an active cement, Ag-Cu eutectic and Cu interlayer

    Lei, Zhao; Xiaohong, Li; Jinbao, Hou; Qiang, Sun; Fuli, Zhang

    2012-10-01

    The interfacial microstructures and mechanical properties of the joints formed by active cement added brazing in vacuum of Cf/SiC composite to Invar alloy, using Ag-Cu eutectic alloy and pure copper foil as braze alloy and interlayer respectively, were investigated. CuTi, Cu4Ti3, Fe2Ti and the reaction layer of TiC and Si were the predominant components at the joint interface. The maximum shear strength of the joint was 77 MPa for brazing at 850 °C for 15 min. The results show that active cement added brazing in vacuum using Ag-Cu eutectic alloy and Cu interlayer can be used successfully for joining Cf/SiC composites to Invar alloy.

  11. Vanadium and niobium additions in pressure vessel steels

    Xu, Peiyuan.

    1992-01-01

    A statistically designed series of vanadium and niobium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in multipass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the niobium 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 (PWHT) at additions of microalloy elements V and Nb on multipass HAZ toughness in the as-welded and PWHT conditions was confirmed. the 50 Joule 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 is not recommended for V/Nb microalloyed HLSA steels. The randomly distributed precipitation of V and Nb carbides (V,Nb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5-15nm, is the predominant alloy carbide precipitate morphology in these steels. Banded morphology of (V,Nb)C precipitation is rarely observed in the HAZ. The volume fraction of (V,Nb)C precipitates increases as increasing V and/or Nb contents in the experimental heats. The volume fraction of precipitates also increases with increasing the PWHT time. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality location to a higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel. An analytical study shows that the influences of additions of microalloy elements V and Nb on yield stress, [sigma][sub y8], and fracture stress, [sigma][sub f], eventuate in the increase of transition temperature in these materials.

  12. Vanadium and columbium additions in pressure vessel steels

    Xu, P.; Somers, B.R.; Pense, A.W. [Lehigh Univ., Bethlehem, PA (United States). ATLSS Center

    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 50 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.

  13. In situ potential distribution measurement in an all-vanadium flow battery.

    Liu, Qinghua; Turhan, Ahmet; Zawodzinski, Thomas A; Mench, Matthew M

    2013-07-18

    An experimental method for measurement of local redox potential within multilayer electrodes was developed and applied to all-vanadium redox flow batteries (VRFBs). Through-plane measurement at the positive side reveals several important phenomena including potential distribution, concentration distribution of active species and the predominant reaction location within the porous carbon electrodes. PMID:23736771

  14. Thermomechanical testing of FeNiCoTi shape memory alloy for active confinement of concrete

    The thermomechanical properties of a new type of shape memory alloy (SMA), FeNiCoTi, are explored in this paper with the aim of examining the feasibility of using this new material as transverse reinforcement for concrete structures subjected to earthquake loading. One advantage of using FeNiCoTi alloy is its cost effectiveness compared to commonly studied NiTi alloy. Differential scanning calorimetry (DSC) tests are conducted to investigate the transformation temperatures of FeNiCoTi alloy under different heat treatment methods and prestrain schemes. First, a heat treatment method is established to produce FeNiCoTi alloy with wide thermal hysteresis that is pertinent to civil structural applications. Next, recovery stress tests are conducted to explore the effect of parameters including heating method, heating temperature, heating rate, heating protocol and prestrain level on the recovery stress. An optimum prestrain level is determined based on the recovery stress results. Moreover, cyclic tests are carried out to examine the cyclic response of FeNiCoTi alloy after stress recovery. Thermal cyclic tests are also carried out on the FeNiCoTi alloy to better understand the effect of temperature variation on the recovery stress. In addition, reheating of the FeNiCoTi alloy after deformation is conducted to examine the reusability of the material after being subjected to excessive deformation. Test results of the FeNiCoTi alloy indicate that this cost-effective SMA can potentially be a promising new material for civil structural applications. (paper)

  15. Thermomechanical testing of FeNiCoTi shape memory alloy for active confinement of concrete

    Chen, Qiwen; Andrawes, Bassem; Sehitoglu, Huseyin

    2014-05-01

    The thermomechanical properties of a new type of shape memory alloy (SMA), FeNiCoTi, are explored in this paper with the aim of examining the feasibility of using this new material as transverse reinforcement for concrete structures subjected to earthquake loading. One advantage of using FeNiCoTi alloy is its cost effectiveness compared to commonly studied NiTi alloy. Differential scanning calorimetry (DSC) tests are conducted to investigate the transformation temperatures of FeNiCoTi alloy under different heat treatment methods and prestrain schemes. First, a heat treatment method is established to produce FeNiCoTi alloy with wide thermal hysteresis that is pertinent to civil structural applications. Next, recovery stress tests are conducted to explore the effect of parameters including heating method, heating temperature, heating rate, heating protocol and prestrain level on the recovery stress. An optimum prestrain level is determined based on the recovery stress results. Moreover, cyclic tests are carried out to examine the cyclic response of FeNiCoTi alloy after stress recovery. Thermal cyclic tests are also carried out on the FeNiCoTi alloy to better understand the effect of temperature variation on the recovery stress. In addition, reheating of the FeNiCoTi alloy after deformation is conducted to examine the reusability of the material after being subjected to excessive deformation. Test results of the FeNiCoTi alloy indicate that this cost-effective SMA can potentially be a promising new material for civil structural applications.

  16. Chemical and mechanical interactions of interstitials with vanadium alloys

    DiStefano, J.R.; Chitwood, L.D.; DeVan, J.H. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Oxidation studies of V-4Cr-4Ti were conducted in air and reduced oxygen partial pressures (10{sup 4}, 10{sup -5} and 10{sup -6} torr). Reaction rates were determined by weight change measurements and chemical analyses. Mechanical properties after the exposures were determined by room temperature tensile tests. In air at 400 and 500{degrees}C, oxide films form on the surface. Initially, rates are high but decrease with time reaching similiar values to those found in oxygen partial pressures at 10{sup -4}, 10{sup -5}, and 10{sup -6} torr. At 400{degrees}C, oxygen pick-up followed a logarithmic function of time and was confined to regions near the surface. Little change in room temperature tensile properties was noted for oxygen increase up to 1500 ppm. Thermal cycling specimens from 400{degrees}C to room temperature up to 14 times had no apparent effect on oxidation rate or tensile properties. At 500{degrees}C, oxygen pick-up appeared to follow a parabolic relation with time. Rates were {approx} 10 times those at 400{degrees}C and correspondingly larger oxygen increases occurred when compared with the 400{degrees}C tests after similiar time periods. This resulted in a significant decrease in total elongation after 240 h. At reduced oxygen partial pressures, rates were measured for times <100 h. Data are relatively sparse but generally show a slightly higher initial rate before slowing. At 400{degrees}C increases to {approx}200 ppm oxygen were found with no effect on room temperature elongation. At 500{degrees}C increase in oxygen of 2400 ppm after 50h/10{sup -5} torr resulted in a decrease of around 25% in room temperature elongation. By comparison, exposure to air at 500{degrees}C for 12 h caused nearly the same results.

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

    Grossbeck, M.L.; King, J.F.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)] [and others

    1997-08-01

    Emphasis has been placed on welding 6.4 mm plate, primarily by gas tungsten arc (GTA) welding. The weld properties were tested using blunt notch Charpy testing to determine the ductile to brittle transition temperature (DBTT). Erratic results were attributed to hydrogen and oxygen contamination of the welds. An improved gas clean-up system was installed on the welding glove box and the resulting high purity welds had Charpy impact properties similar to those of electron beam welds with similar grain size. A post-weld heat treatment (PWHT) of 950{degrees}C for two hours did not improve the properties of the weld in cases where low concentrations of impurities were attained. Further improvements in the gas clean-up system are needed to control hydrogen contamination.

  18. Effect of hydrogen accumulation on mechanical property and microstructure of V-Cr-Ti alloys

    Pure vanadium, V-5Cr, V-5Ti and V-5Cr-5Ti alloys doped with different amounts of hydrogen were tested under tension and observed under TEM in order to clarify the interaction between hydrogen and vanadium. Hydrogenated samples tested under tension showed a typical hydrogen-embrittlement behavior. TEM observation suggests that the embrittlement is caused by hydrogen diffusion at the triple point of grain boundaries, hydride formation and the subsequent generation of dislocations and micro-cracks

  19. A proposal to alloy design for low activation high manganese austenitic stainless steel - role of carbon and nitrogen

    The role of carbon and nitrogen in high Mn-Cr-Fe base alloy has been investigated in order to propose a favorable starting composition for a low activation austenitic stainless steel. The base composition of Fe-12% Cr-15% Mn was selected by the results of our previous study, because of prevention of δ ferrite formation and retardation of σ phase. The combined addition of carbon and nitrogen is very beneficial in making a stable γ phase, preventing σ phase formation and increasing high-temperature strength at around 875 K. Cold work of 20% is also very useful in increasing creep rupture strength because of finely dispersed precipitation of carbide during creep. From the consideration of these results, an alloy system of Fe-12% Cr-15% Mn-0.2% C-0.2% N has been designed as one of the preferable primary low activation austenitic stainless steel. (orig.)

  20. Titanium oxynitride interlayer to influence oxygen reduction reaction activity and corrosion stability of Pt and Pt-Ni alloy.

    Tan, XueHai; Wang, Liya; Zahiri, Beniamin; Kohandehghan, Alireza; Karpuzov, Dimitre; Lotfabad, Elmira Memarzadeh; Li, Zhi; Eikerling, Michael H; Mitlin, David

    2015-01-01

    A key advancement target for oxygen reduction reaction catalysts is to simultaneously improve both the electrochemical activity and durability. To this end, the efficacy of a new highly conductive support that comprises of a 0.5 nm titanium oxynitride film coated by atomic layer deposition onto an array of carbon nanotubes has been investigated. Support effects for pure platinum and for a platinum (50 at %)/nickel alloy have been considered. Oxynitride induces a downshift in the d-band center for pure platinum and fundamentally changes the platinum particle size and spatial distribution. This results in major enhancements in activity and corrosion stability relative to an identically synthesized catalyst without the interlayer. Conversely, oxynitride has a minimal effect on the electronic structure and microstructure, and therefore, on the catalytic performance of platinum-nickel. Calculations based on density functional theory add insight with regard to compositional segregation that occurs at the alloy catalyst-support interface. PMID:25470445

  1. Elemental investigation of (Al-Cu) alloys and some geological samples using neutron activation and XRF analysis techniques

    Neutron activation analysis (NAA) using k0 - standardization (k0-NAA) is well known method for multi-elemental analysis. The method is used to analyze different samples belonging to different fields. In addition, X- ray fluorescence (XRF) is also used for multi-elemental analysis. XRF complements NAA methods. Both methods were used for investigation of some iron ores and aluminum- cupper alloy (Al-Cu) samples. Elemental concentration of Iron ores and Al-Cu alloy samples were determined by k0 - NAA and XRF methods. The iron ore samples were collected from Wadi Kareim and Umm Nar sites (the Eastern desert of Egypt). Six and two samples representing the ores of Wadi Kareim and Umm Nar, respectively altogether with the standard samples consisting of Fe, Au , Zr and W and the certified reference sample IAEA Soil-7 were irradiated in one of the irradiated boxes at the Second Egyptian Research Reactor (ETRR- 2). The induced activities were counted using an efficiency calibrated HPGe detector systems. The neutron spectrum parameters α and f characterizing the neutron irradiation position that are needed in applying k0-NAA method were determined using the activation product of Zr , Au, Fe and W and found α≅ - 0.048 ±0.002 and f ≅ 38± k0 -NAA method was applied to determine the elemental concentrations in the two iron ore samples. The concentrations determined were found to vary erratically form one sample to another. The results were discussed and compared with similar results in literature. The accuracy of the k0 - NAA method was checked by determining the elemental concentration in the IAEA-Soil 7 reference sample. The obtained results are compared with the recommended values. Good agreements were found within 10 %. Short time neutron activation analysis (STNAA) was carried out to determine concentration of major elements in Al-Cu alloy samples. Three (Al-Cu) alloys samples with different concentrations of Cu (2, 3.5 and 5 %) altogether. Au standard sample (bare

  2. Vanadium bioavailability in soils amended with blast furnace slag

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg−1) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment

  3. Vanadium bioavailability in soils amended with blast furnace slag.

    Larsson, Maja A; Baken, Stijn; Smolders, Erik; Cubadda, Francesco; Gustafsson, Jon Petter

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg(-1)) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment. PMID:25917693

  4. Vanadium bioavailability in soils amended with blast furnace slag

    Larsson, Maja A., E-mail: maja.larsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Baken, Stijn, E-mail: stijn.baken@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Smolders, Erik, E-mail: erik.smolders@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Cubadda, Francesco, E-mail: francesco.cubadda@iss.it [Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome 00161 (Italy); Gustafsson, Jon Petter, E-mail: jon-petter.gustafsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Brinellvägen 28, 100 44 Stockholm (Sweden)

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg{sup −1}) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.

  5. Thermal desorption of gases from aluminum alloy Al 6061, their rates and activation energies

    The use of Al in the construction of the vacuum chamber of intersecting proton storage rings has several advantages over the use of stainless steel. We have, therefore, undertaken UHV studies on long pipes made of Al alloy 6061 to see whether this material could be used in the proposed proton intersecting storage accelerator facility ISABELLE at Brookhaven. The outgassing rates, measured by two different methods, are compared for several surface treatments and three bakeout temperatures. The lowest outgassing rate of less than 1x10-14 Torr l s-1cm-2 was obtained with Ar and O2 discharge cleaning. The residual gas in the pipe contained more than 99% H2 with traces of CO and CO2. By observing the temperature dependence of the desorption of these gases, we have measured the heat of diffusion of H2 (E/sub H/2=10.5+-1.0 kcal/mole) and the thermal activation energies of CO (E/sub CO/=29+-2 kcal/mole) and CO2 (E/sub CO/2=25+-2 kcal/mole). Ar, with a peak desorption at 280degree--300 degreeC, also appears to be embedded in the metal. Since all commercially available UHV equipment uses stainless steel flanges, we have investigated the behavior of the stainless steel to Al transitions up to 350degreeC

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

    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. PMID:25578410

  7. One-pot synthesis of platinum–palladium–cobalt alloyed nanoflowers with enhanced electrocatalytic activity for ethylene glycol oxidation

    Graphical abstract: A facile one-pot solvothermal method was developed for synthesis of Pt–Pd–Co alloyed nanoflowers using oleylamine as the solvent, surfactant and reducing agents, along with cetylpyridinium chloride (CPC) as the co-surfactant and shape-directing agents. The nanocrystals displayed highly electrocatalytic activity and stability toward EG oxidation. Display Omitted - Highlights: • Pt–Pd–Co alloyed nanoflowers were prepared by a facile one-pot solvothermal method. • Oleylamine was used as the solvent, surfactant and reducing agents. • CPC was employed as the co-surfactant and shape-directing agents. • Pt–Pd–Co nanocrystals exhibited improved electrocatalytic activity and high stability for EG oxidation. - Abstract: In this work, three-dimensional trimetallic Pt–Pd–Co alloyed nanoflowers are fabricated by a facile one-pot solvothermal strategy, with the assistance of oleylamine as the solvent, surfactant, and reducing agents, along with cetylpyridinium chloride (CPC) as the co-surfactant and shape-directing agents. Their morphology and crystal structure were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscope (STEM), and X-ray photoelectron spectra (XPS) in details. The respective electrochemically active surface area (ECSA) is estimated to be 32.53 m2 g−1, and current density is 132.91 mA cm−2 for the electrooxidation of ethylene glycol (EG). These values are much higher than those of PtPdCo nanoparticles, PtPd nanoparticles, commercial Pt black, and Pd black under the identical conditions, showing the improved catalytic activity of Pt–Pd–Co nanoflowers. The excellent performances are attributed to the specific structure and synergistic interactions of the trimetallic alloy. The as-prepared nanoflowers can serve as a promising electrocatalyst in fuel cells

  8. Extraction-complexonometric determination of vanadium(4) in the presence of vanadium(3)

    The extraction-complexonometric method has been investigated for determining vanadium(4) in the presence of vanadium (3) with high contents of these forms in the solution analyzed. The method of separation of V(4) and V(3) is based on extraction of the ion acetate of vanadium(4) with eriochrome red B(ERCB) and diphenyl quanidinium (DPG) by a mixture of chloroform and isoamyl alcohol (3:1). To control the content of V(4) and V(3) the method of reciprocal complexonometric titration is used (the titrating solution was a solution of thorium nitride, and xylenol orange was a solution of thorium nitride, and xylenol orange was used as metal indicator). Titration has been carried out in an acid solution at pH=2.8. The developed method has been applied to analysis of lithium-zinc spinels containing both forms of vanadium

  9. Hydrogen reduction of vanadium in vanadium-doped LiMnPO{sub 4}

    Kellerman, D.G., E-mail: kellerman@ihim.uran.ru [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Ural Federal University, 620002 Ekaterinburg (Russian Federation); Chukalkin, Yu.G. [Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Medvedeva, N.I.; Kuznetsov, M.V. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Mukhina, N.A. [Eliont LLC, 620137 Ekaterinburg (Russian Federation); Semenova, A.S. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Gorshkov, V.S. [Eliont LLC, 620137 Ekaterinburg (Russian Federation)

    2015-01-15

    The samples of vanadium-doped LiMnPO{sub 4} have been synthesized by the solid-state reaction technique. To reduce the oxidation state of vanadium from V{sup 5+} to V{sup 4+}, the samples have been additionally annealed under hydrogen atmosphere. The tetravalent state of vanadium was proved by analysis of V 2p X-ray photoelectron spectra. Raman spectroscopy, first-principle studies and magnetic measurements were used to determine the effect of V{sup 4+} on the Li–Mn phosphate properties. - Highlights: • The samples of LiMnPO{sub 4} doped with vanadium were prepared. • The samples were annealed under hydrogen atmosphere. • The V{sup 4+} presence was proved. • The ab initio calculations revealed the most favorable position for oxygen vacancy. • The presence of V{sup 4+} changes magnetic properties and Raman spectra of LiMnPO{sub 4}.

  10. Biological effects of activation products and other chemicals released from fusion power plants

    Literature reviews indicate that existing information is incomplete, often contradictory, and of questionable value for the prediction and assessment of ultimate impact from fusion-associated activation products and other chemical releases. It is still uncertain which structural materials will be used in the blanket and first wall of fusion power plants. However, niobium, vanadium, vanadium-chromium alloy, vanadium-titanium alloy, sintered aluminum product, and stainless steel have been suggested. The activation products of principal concern will be the longer-lived isotopes of 26Al, 49V, 51Cr, 54Mn, 55Fe, 58Co, 60Co, 93Nb, and 94Nb. Lithium released to the environment either during the mining cycle, from power plant operation or accident, may be in the form of a number of compound types varying in solubility and affinity for biological organisms. The effects of a severe liquid metal fire or explosion involving Na or K will vary according to inherent abiotic and biotic features of the affected site. Saline, saline-alkaline, and sodic soils of arid lands would be particularly susceptible to alkaline stress. Beryllium released to the environment during the mining cycle or reactor accident situation could be in the form of a number of compound types. Adverse effects to aquatic species from routine chemical releases (biocides, corrosion inhibitors, dissolution products) may occur in the discharge of both fission and fusion power plant designs

  11. ENVIRONMENTALLY COMPLIANT CORROSION-ACTIVATED INHIBITOR SYSTEM FOR ALUMINUM ALLOYS - PHASE I

    The federal government is estimated to spend $1 billion on painting/repainting aircraft annually. Aircraft have surfaces composed of aluminum alloys that are highly susceptible to corrosion and must be protected with corrosion-preventative treatments that typically conta...

  12. Effects of Hard Surface Grinding and Activation on Electroless-Nickel Plating on Cast Aluminium Alloy Substrates

    Olawale Olarewaju Ajibola

    2014-01-01

    Full Text Available This work examined effects of hard surface polishing grits and activation on electroless-nickel (EN plating on cast aluminium alloy substrates in sodium hypophosphite baths. As-received aluminium alloy sample sourced from automobile hydraulic brake master cylinder piston was melted in electric furnace and sand cast into rod. The cast samples were polished using different grits (60 μm–1200 μm before plating. The effects on adhesion, appearance, and quantity of EN deposits on substrates were studied. Observation shows that the quantity of EN deposit is partly dependent on the alloy type and roughness of the surface of the substrates, whereas the adhesion and brightness are not solely controlled by the degree of surface polishing. The best yield in terms of adhesion and appearance was obtained from the activation in zincate and palladium chloride solutions. Higher plating rates (g/mm2/min of 3.01E-05, 2.41E-05, and 2.90E-05 were obtained from chromate, zincate, and chloride than 8.49E-06, 8.86E-06, and 1.69E-05 as obtained from HCl etched, NaOH, and H2O activated surfaces, respectively.

  13. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  14. Design, synthesis and pharmacological evaluation of novel vanadium-containing complexes as antidiabetic agents.

    Elena V Fedorova

    Full Text Available 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(iminomethyl]carbamato}oxovanadium (IV and sodium(2,2'-Bipyridyloxo-diperoxovanadate(V octahydrate were identified as the most potent hypoglycemic agents among the synthesized compounds.

  15. The effect of dissolved stainless steel alloy elements on the activity and growth of SRB

    F. A. Lopes; Morin, P.; Oliveira, Rosário; Melo, L. F.

    2000-01-01

    Sulphate reducing bacteria have an important role in the sulphur cycle, and therefore in wastewater treatment systems. They are able to form biofilms on metallic surfaces, leading to fouling and corrosion problems. These bacteria are among the micro-organisms most frequently implicated in microbial corrosion of iron and ferrous alloys. Alloying elements added to steels for the improvement of their corrosion resistance such as molybdenum and nickel can be dissolved in bulk liqui...

  16. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF[sub 2], ThO[sub 2], YDT(0.85ThO[sub 2]-0.15YO[sub 1.5]), and LDT(0.85ThO[sub 2]- 0.15LaO[sub 1.5]) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  17. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF{sub 2}, ThO{sub 2}, YDT(0.85ThO{sub 2}-0.15YO{sub 1.5}), and LDT(0.85ThO{sub 2}- 0.15LaO{sub 1.5}) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  18. Antimicrobial Activity of Copper Alloys Against Invasive Multidrug-Resistant Nosocomial Pathogens.

    Eser, Ozgen Koseoglu; Ergin, Alper; Hascelik, Gulsen

    2015-08-01

    The emergence and spread of antibiotic resistance demanded novel approaches for the prevention of nosocomial infections, and metallic copper surfaces have been suggested as an alternative for the control of multidrug-resistant (MDR) bacteria in surfaces in the hospital environment. This study aimed to evaluate the antimicrobial activity of copper material for invasive MDR nosocomial pathogens isolated over time, in comparison to stainless steel. Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) (n:4), OXA-23 and OXA-58 positive, MDR Acinetobacter baumannii (n:6) and Pseudomonas aeruginosa (n:4) were evaluated. The antimicrobial activity of coupons containing 99 % copper and a brass alloy containing 63 % copper was assessed against stainless steel. All the materials demonstrated statistically significant differences within each other for the logarithmic reduction of microorganisms. Among the three materials, the highest reduction of microorganisms was seen in 99 % copper and the least in stainless steel. The result was statistically significant especially for 0, 2, and 4 h (P = 0.05). 99 % copper showed a bactericidal effect at less than 1 h for MRSA and at 2 h for P. aeruginosa. 63 % copper showed a bactericidal effect at 24 h for P. aeruginosa strains only. Stainless steel surfaces exhibited a bacteriostatic effect after 6 h for P. aeruginosa strains only. 99 % copper reduced the number of bacteria used significantly, produced a bactericidal effect and was more effective than 63 % copper. The use of metallic copper material could aid in reducing the concentration of bacteria, especially for invasive nosocomial pathogens on hard surfaces in the hospital environment. PMID:26044991

  19. Hydride phase equilibria in V-Ti-Ni alloy membranes

    Highlights: • V70Ti15Ni15 (at.%) comprises a vanadium solid solution plus NiTi and NiTi2. • Dissolution of Ni and Ti into vanadium solid solution increase critical temperature for BCT β-hydride formation. • Three VSS hydride phase fields were observed: BCC, BCC + BCT, BCT + BCT. • NiTi and NiTi2 phases do not stabilise the alloy against brittle failure. - Abstract: Vanadium is highly permeable to hydrogen which makes it one of the leading alternatives to Pd alloys for hydrogen-selective alloy membrane applications, but it is prone to brittle failure through excessive hydrogen absorption and transitions between the BCC α and BCT β phases. V-Ti-Ni alloys are a prospective class of alloy for hydrogen-selective membrane applications, comprising a highly-permeable vanadium solid solution and several interdendritic Ni-Ti compounds. These Ni-Ti compounds are thought to stabilise the alloy against brittle failure. This hypothesis was investigated through a systematic study of V70Ti15Ni15 by hydrogen absorption and X-ray diffraction under conditions relevant to membrane operation. Dissolved hydrogen concentration in the bulk alloy and component phases, phase identification, thermal and hydrogen-induced expansion, phase quantification and hydride phase transitions under a range of pressures and temperatures have been determined. The vanadium phase passes through three different phase fields (BCC, BCC + BCT, BCT + BCT) during cooling under H2 from 400 to 30 °C. Dissolution of Ni and Ti into the vanadium phase increases the critical temperature for β-hydride formation from <200 to >400 °C. Furthermore, the Ni-Ti phases also exhibit several phase transitions meaning their ability to stabilise the alloy is questionable. We conclude that this alloy is significantly inferior to V with respect to its stability when used as a hydrogen-selective membrane, but the hydride phase transitions suggest potential application for high-temperature hydrogen and thermal energy

  20. Numerical analysis of vanadium crossover effects in all-vanadium redox flow batteries

    Highlights: • The effects of vanadium crossover of VRFBs are examined by numerical method. • The evolution of vanadium ions are investigated with fresh and degraded membranes. • The magnitude of crossover is studied with various thickness of membrane. • The capacity loss is intensified as the membrane is degraded. - ABSTRACT: In this work, a crossover model is newly developed to account rigorously for the crossover of vanadium ions through the membrane and resultant side reactions occurring in both positive and negative electrodes. The crossover model is then numerically coupled with previously developed three-dimensional (3-D), transient, thermal VRFB model in which key physicochemical phenomena including the electrochemical reactions, waste heat generation, resultant species and heat transport are all included. Using the comprehensive VRFB model, we investigate the effects of vanadium crossover between the negative and positive electrodes during a single charge/discharge cycle. Numerical simulations successfully capture capacity loss related to vanadium crossover, clearly showing the difference in species distributions due to side reactions. The results show that due to effect of vanadium ion crossover, more charging time and less discharging time have been achieved

  1. Magang‘s 20 t Top Blowing BOF Used for Extracting Vanadium

    1999-01-01

    Because that vanadium sells well recently in market and the Maagng's iron ore ontains higher vanadium,Magang decied to use its 20 t top blowing BOF to extract vanadium in steel-makin.Production result showed that the extracted vanadium slag reached the expected target of V2O3 compsoition.The recovery rate of vanadium is up to 80%

  2. Three-dimensional hierarchical porous platinum-copper alloy networks with enhanced catalytic activity towards methanol and ethanol electro-oxidation

    Fan, Yang; Liu, Pei-Fang; Zhang, Zong-Wen; Cui, Ying; Zhang, Yan

    2015-11-01

    Porous Pt-Cu alloy networks are synthesized through a one-pot hydrothermal process, with ethylene glycol as the reducing agent and the block copolymer Pluronic F127 as structure-directing agent. The structure, porosity and surface chemical state of as-prepared Pt-Cu alloy with different composition are characterized. The formation mechanism of the porous structure is investigated by time sequential experiments. The obtained Pt53Cu47 alloy possesses a unique 3D hierarchical porous network structure assembled by interconnected nanodendrites as building blocks. Because of the high surface area, concave surface topology and open porous structure, the Pt53Cu47 alloy catalyst exhibits enhanced catalytic activity towards methanol and ethanol electro-oxidation in comparison with commercial Pt black and the Pt73Cu27 alloy synthesized following the same process as Pt53Cu47.

  3. Study of propane partial oxidation on vanadium-containing catalysts

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  4. Lithium insertion in sputtered vanadium oxide film

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.;

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  5. Electrochemical doping of vanadium oxide nanotubes

    Vanadium oxide nanotubes (VOx-NTs) exhibit diverse properties ranging from spin frustration and semiconductivity to ferromagnetism by doping with either electrons or holes. We have applied optical, photoemission and EELS as well as static magnetization, ESR and NMR studies in order to obtain insight into the rich physics of these materials. Our data suggest an averaged vanadium valency of about +4.4 in the undoped case. We observe two magnetically nonequivalent vanadium sites, attributed to V4+ ions (3d1,S=1/2) in octahedral and tetrahedral oxygen coordination and there are strong indications that antiferromagnetic dimers and trimers occur in the vanadium-spin chains in the walls. We find a spin gap of the order of 700 K. Upon electron doping of VOx-NTs, our spectroscopic data confirm a higher number of magnetic V4+ sites. Besides, the magnetic response was studied after the electrochemical insertion of lithium. For certain doping levels, a ferromagnetic signal at room temperature was found. (orig.)

  6. Anti-diabetic effects of a series of vanadium dipicolinate complexes in rats with streptozotocin-induced diabetes.

    Willsky, Gail R; Chi, Lai-Har; Godzala, Michael; Kostyniak, Paul J; Smee, Jason J; Trujillo, Alejandro M; Alfano, Josephine A; Ding, Wenjin; Hu, Zihua; Crans, Debbie C

    2011-10-01

    The effects of oral treatment of rats with streptozotocin-induced diabetes with a range of vanadium dipicolinate complexes (Vdipic) and derivatives are reviewed. Structure-reactivity relationships are explored aiming to correlate properties such as stability, to their insulin-enhancing effects. Three types of modifications are investigated; first, substitutions on the aromatic ring, second, coordination of a hydroxylamido group to the vanadium, and third, changes in the oxidation state of the vanadium ion. These studies allowed us to address the importance of coordination chemistry, and redox chemistry, as modes of action. Dipicolinate was originally chosen as a ligand because the dipicolinatooxovanadium(V) complex (V5dipic), is a potent inhibitor of phosphatases. The effect of vanadium oxidation state (3, 4 or 5), on the insulin-enhancing properties was studied in both the Vdipic and VdipicCl series. Effects on blood glucose, body weight, serum lipids, alkaline phosphatase and aspartate transaminase were selectively monitored. Statistically distinct differences in activity were found, however, the trends observed were not the same in the Vdipic and VdipicCl series. Interperitoneal administration of the Vdipic series was used to compare the effect of administration mode. Correlations were observed for blood vanadium and plasma glucose levels after V5dipic treatment, but not after treatment with corresponding V4dipic and V3dipic complexes. Modifications of the aromatic ring structure with chloride, amine or hydroxyl groups had limited effects. Global gene expression was measured using Affymetrix oligonucleotide chips. All diabetic animals treated with hydroxyl substituted V5dipic (V5dipicOH) and some diabetic rats treated with vanadyl sulfate had normalized hyperlipidemia yet uncontrolled hyperglycemia and showed abnormal gene expression patterns. In contrast to the normal gene expression profiles previously reported for some diabetic rats treated with vanadyl

  7. Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel

    DMR-249A is a low carbon microalloyed high-strength low-alloy (HSLA) steel. While DMR-249A plates of thickness less than 18 mm meet the specified room temperature yield strength (390 MPa) and Charpy impact toughness (78J at -60 deg. C) in the as-rolled condition, thicker plates require water quenching and tempering. Elimination of the quenching and tempering treatment can result in significant cost and energy savings besides offering increased productivity. Therefore, in the present work, modifications to the base DMR-249A steel composition have been investigated with the objective of producing thicker gage plates (24 mm) capable of meeting the specified properties in the normalized condition. Plates from three modified compositions i.e., containing 0.015 wt.% titanium and 0.06, 0.09 and 0.12 wt.% vanadium respectively and one composition with 0.10 wt.% vanadium, and without any titanium were investigated over a range of normalizing temperatures (875-1000 deg. C). In all cases, only the steel without titanium met the specified properties in the normalized condition. Microstructural investigations using scanning and transmission electron microscopy, as well as support evidence from calculations performed using ThermoCalc software, suggest that this is due to the presence of nanoscale vanadium rich carbonitride particles distributed throughout the matrix. These particles were absent in the titanium-containing steel at a similar vanadium level.

  8. Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel

    Show, B.K., E-mail: bijay_show@rediffmail.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Veerababu, R., E-mail: veeru_met@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Balamuralikrishnan, R., E-mail: bmk_pgh@yahoo.com [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India); Malakondaiah, G., E-mail: director@dmrl.drdo.in [Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad 500058, Andhra Pradesh (India)

    2010-03-15

    DMR-249A is a low carbon microalloyed high-strength low-alloy (HSLA) steel. While DMR-249A plates of thickness less than 18 mm meet the specified room temperature yield strength (390 MPa) and Charpy impact toughness (78J at -60 deg. C) in the as-rolled condition, thicker plates require water quenching and tempering. Elimination of the quenching and tempering treatment can result in significant cost and energy savings besides offering increased productivity. Therefore, in the present work, modifications to the base DMR-249A steel composition have been investigated with the objective of producing thicker gage plates (24 mm) capable of meeting the specified properties in the normalized condition. Plates from three modified compositions i.e., containing 0.015 wt.% titanium and 0.06, 0.09 and 0.12 wt.% vanadium respectively and one composition with 0.10 wt.% vanadium, and without any titanium were investigated over a range of normalizing temperatures (875-1000 deg. C). In all cases, only the steel without titanium met the specified properties in the normalized condition. Microstructural investigations using scanning and transmission electron microscopy, as well as support evidence from calculations performed using ThermoCalc software, suggest that this is due to the presence of nanoscale vanadium rich carbonitride particles distributed throughout the matrix. These particles were absent in the titanium-containing steel at a similar vanadium level.

  9. Direct Oxidation of Benzene to Phenol by Dioxygen over Nano-vanadium Oxide

    GAO, Xiaohan; L(U), Xuechuan; XU, Jie

    2009-01-01

    Reducing regents, such as ascorbic acid, are needed for vanadium-containing catalysts to catalyze the direct oxidation of benzene to phenol by dioxygen. Quadrivalent vanadium species, reduced from quinquevalent vanadium species, can activate dioxygen to produce active oxygen species, which is important for the reaction. The key step is to prepare more V~(4+)-containing catalysts. Here, VO_X-C_(16)-A was prepared in an acidic medium to produce more V~(4+) species. The results of XPS and XRD studies confirmed that the vanadium species in VO_X-C_(16)-A was mainly V~(4+) ions. The results of XRD and electron diffraction patterns revealed that VO_X-C_(16)-A consisted of tetragonal VO_2 and monoclinic VO_2. Morphology observations display that the VO_X-C_(16)-A is made of nanorod. Investigations into the performances of the catalysts showed that VO_X-C_(16)-A was reusable, producing a 1.9% conversion of benzene without reducing agent.

  10. Preparation of AZ91D magnesium alloy semi-solid billet by new strain induced melt activated method

    JIANG Ju-fu; LUO Shou-jing; ZOU Jing-xiang

    2006-01-01

    New strain induced melt activated (new SIMA) method for preparing AZ91D magnesium alloy semi-solid billet is introduced by applying equal channel angular extrusion into strain induced step in SIMA method, by which semi-solid billet with fine spheroidal grains and average grain size of 18 μm can be prepared. Furthermore, average grain size of semi-solid billet is reduced with increasing extrusion pass of AZ91D magnesium alloy obtained in ECAE process. By using semi-solid billet prepared by new SIMA, thixoforged magazine plates component with high mechanical properties such as yield strength of 201.4 MPa, ultimate tensile strength of 321.8 MPa and elongation of 15.3%, can be obtained.

  11. Synthesis of Vanadium Nitride by a One Step Method

    Sansan YU; Nianxin FU; Feng GAO; Zhitong SUI

    2007-01-01

    Vanadium nitrides were prepared via one step method of carbothermal reduction and nitridation of vanadium trioxide. Thermalgravimetric analysis (TGA) and X-ray diffraction were used to determine the reaction paths of vanadium carbide, namely the following sequential reaction: V2O3→V8C7 in higher temperature stage, the rule of vanadium nitride synthesized was established, and defined conditions of temperature for the production of the carbides and nitrides were determined. Vanadium oxycarbide may consist in the front process of carbothermal reduction of vanadium trioxide. In one step method for vanadium nitride by carbothermal reduction and nitridation of vanadium trioxide, the nitridation process is simultaneous with the carbothermal reduction. A one-step mechanism of the carbothermal reduction with simultaneous nitridation leaded to a lower terminal temperature in nitridation process for vanadium nitride produced, compared with that of carbothermal reduction process without nitridation. The grain size and shape of vanadium nitride were uniform, and had the shape of a cube. The one step method combined vacuum carborization and nitridation (namely two step method) into one process. It simplified the technological process and decreased the costs.

  12. Activity and Stability of Rare Earth-Based Hydride Alloys as Catalysts of Hydrogen Absorption-Oxidation Reactions

    Ying Taokai(应桃开); Gao Xueping(高学平); Hu Weikang(胡伟康); Noréus Dag

    2004-01-01

    Rare earth-based AB5-type hydrogen storage alloys as catalysts of hydrogen-diffusion electrodes for hydrogen absorption and oxidation reactions in alkaline fuel cells were investigated. It is demonstrated that the meta-hydride hydrogen-diffusion electrodes could be charged by hydrogen gas and electrochemically discharged at the same time to retain a stable oxidation potential for a long period. The catalytic activities and stability are almost comparable with a Pt catalyst on the active carbon. Further improvement of performances is expected via reduction of catalyst size into nanometers.

  13. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  14. Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

    Y. H. Taufiq-Yap; Y.C. Wong; Z. Zainal; M.Z. Hussein

    2009-01-01

    Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V_2O_5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction (XRD),scanning electron microscope (SEM),transmission electron microscope (TEM) and temperature-programmed reduction (TPR) in H_2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction (TPRn). Catalytic evaluation of the sonochemical treated V_2O_5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V_2O_5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform,well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H_2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V_2O_5 compared to the bulk. Furthermore,the nanorod vanadium oxide bundles,which were produced after 90,120 and 180 min of sonochemical treatment,showed an additional reduction peak at lower temperature (~850 K),suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V_2O_5 with highly active oxygen species showed markedly higher activity than the bulk material,which was further proven by catalytic oxidation of n-butane.

  15. On vanadium oxide dissolution in sodium carbonate solutions

    Kinetics of dissolution process of powdered vanadium (5) oxide in sodium carbonate is studied. Activation energy of chemical dissolution of V2O5 at sodium carbonate concentration up to 0.6 mol/dm3 constitutes 35.2 kJ/mol. With sodium carbonate concentration increase the dissolution activation energy decreases to 32.5 kJ/mol. Absolute values of activation energy of the dissolution process, dependence of the reaction order on the temperature in the range of low sodium carbonate concentration, testify to the presence of kinetic difficulties in the process studied. Thus, the process of V2O5 dissolution in sodium carbonate solutions proceeds in the mixed region and obeys regularities of the mixed kinetics

  16. Effects of V Addition on Microstructure and Hardness of Fe-C-B-Ni-V Hardfacing Alloys Cast on Steel Substrates

    Rovatti, L.; Lemke, J. N.; Emami, A.; Stejskal, O.; Vedani, M.

    2015-12-01

    Fe-based hardfacing alloys containing high volume fraction of hard phases are a suitable material to be deposited as wear resistant thick coatings. In the case of alloys containing high amount of interstitial alloying elements, a key factor affecting the performance is dilution with the substrate induced by the coating process. The present research was focused on the analysis of V-bearing Fe-based alloys after calibrated carbon and vanadium additions (in the range from 3 to 5 wt.%) to a commercial Fe-C-B-Ni hardfacing alloy. Vanadium carbides with a petal-like morphology were observed in the high-V hypereutectic alloys allowing to reach hardness values above 700 HV. The solidification range shifted to higher temperatures with increasing amount of vanadium addition and in the case of hypereutectic alloys, the gap remains close to that of the original alloy. In the last step of the research, the microstructural evolution after dilution was analyzed by casting the V-rich alloys on a steel substrate. The dilution, caused by the alloying element diffusion and the local melting of the substrate, modified the microstructure and the hardness for a relevant volume fraction of the hardfacing alloys. In particular, the drop of interstitial elements induced the transition from the hypereutectic to the hypoeutectic microstructure and the formation of near-spherical V-rich carbides. Even after dilution, the hardness of the new alloys remained higher than that measured in the original Fe-C-B-Ni alloy.

  17. High-temperature thermodynamic activities of zirconium in platinum alloys determined by nitrogen-nitride equilibria

    A high-temperature nitrogen-nitride equilibrium apparatus is constructed for the study of alloy thermodynamics to 23000C. Zirconium-platinum alloys are studied by means of the reaction 9ZrN + 11Pt → Zr9Pt11 + 9/2 N2. Carful attention is paid to the problems of diffusion-limited reaction and ternary phase formation. The results of this study are and a/sub Zr//sup 19850C/ = 2.4 x 10-4 in Zr9Pt11 ΔG/sub f 19850C/0 Zr9Pt11 less than or equal to -16.6 kcal/g atom. These results are in full accord with the valence bond theory developed by Engel and Brewer; this confirms their prediction of an unusual interaction of these alloys

  18. The activation/depassivation of nickel–chromium–molybdenum alloys in bicarbonate solution: Part I

    Electrochemical and surface analytical techniques (X-ray photoelectron and Auger spectroscopies) were used to characterize the influence of potential on the properties of the oxide film formed on the Hybrid BC-1 (a Ni–Cr–Mo) alloy in chloride solutions containing bicarbonate. In the passive region the film possesses the expected bilayer structure with a Cr(III)-dominated barrier layer containing mixed oxidation states of Mo and an outer dominantly-hydroxide layer. At more positive potentials the Cr/Mo content of the film decreases when bicarbonate is present and the alloy becomes covered by a thick (>100 nm), and only partially protective, Ni(OH)2 layer

  19. Joining of CBN abrasive grains to medium carbon steel with Ag-Cu/Ti powder mixture as active brazing alloy

    Ding, W.F. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)]. E-mail: dingwf2000@vip.163.com; Xu, J.H. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Shen, M. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Su, H.H. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Fu, Y.C. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Xiao, B. [College of Mechanical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2006-08-25

    In order to develop new generation brazed CBN grinding wheels, the joining experiments of CBN abrasive grains and medium carbon steel using the powder mixture of Ag-Cu alloy and pure Ti as active brazing alloy are carried out at elevated temperature under high vacuum condition. The relevant characteristics of the special powder mixture, the microstructure of the interfacial region, which are both the key factors for determining the joining behavior among the CBN grains, the filler layer and the steel substrate, are investigated extensively by means of differential thermal analysis (DTA), scanning electron microscope (SEM) and energy dispersion spectrometer (EDS), as well X-ray diffraction (XRD) analysis. The results show that, similar to Ag-Cu-Ti filler alloy, Ag-Cu/Ti powder mixture exhibits good soakage capability to CBN grains during brazing. Moreover, Ti in the powder mixture concentrates preferentially on the surface of the grains to form a layer of needlelike Ti-N and Ti-B compounds by chemical metallurgic interaction between Ti, N and B at high temperature. Additionally, based on the experimental results, the brazing and joining mechanism is deeply discussed in a view of thermodynamic criterion and phase diagram of Ti-B-N ternary system.

  20. Influence of alloying elements and nitrogen content on deformation resistance of chromium-nickel stainless steels

    Four groups of steels with a type Kh20N15 matrix differing in the contents of nitrogen and additional alloying element (Cu, Si, V or Nb) were studied for the influence of the alloying system on deformation resistance in hot rolling. The one-pass rolling was carried out at 900, 1000, 1100 and 1200 deg C with 20, 40 and 60 % reductions. Experimental data statistical processing showed that vanadium alloying results in a sharp increase of nitrogen content influence comparable with strain hardening. The hardening effect in copper- and silicon-containing alloys almost is independent of nitrogen concentration. Niobium-containing alloys lie between two above mentioned groups

  1. Impact of Vanadium Complexes Treatment on the Oxidative Stress Factors in Wistar Rats Plasma

    R. Francik

    2011-01-01

    Full Text Available The aim of this study was to investigate the clinical efficacy of vanadium complexes on triglycerides (TG, total cholesterol (Chol, uric acid (UA, urea (U, and antioxidant parameters: nonenzymatic (FRAP—ferric reducing ability of plasma, and reduced glutathione—GSH and enzymatic (glutathione peroxidase—GPx, catalase—CAT, and GPx/CAT ratio activity in the plasma of healthy male Wistar rats. Three vanadium complexes: [VO(bpy2]SO4⋅2H2O, [VO(4,4′Me2bpy2]SO4⋅2H2O, and Na[VO(O22(bpy]⋅8H2O are administered by gavage during 5 weeks in two different diets such as control (C and high fatty (F diets. Changes of biochemical and antioxidants parameters are measured in plasma. All three vanadium complexes statistically decrease the body mass growth in comparison to the control and fatty diet. In plasma GSH was statistically increased in all vanadium complexes-treated rats from control and fatty group in comparison to only control group. Calculated GPX/CAT ratio was the highest in the control group in comparison to others.

  2. A Contemporary Treatment Approach to Both Diabetes and Depression by Cordyceps sinensis, Rich in Vanadium

    Jian-You Guo

    2010-01-01

    Full Text Available Diabetes mellitus is accompanied by hormonal and neurochemical changes that can be associated with anxiety and depression. Both diabetes and depression negatively interact, in that depression leads to poor metabolic control and hyperglycemia exacerbates depression. We hypothesize one novel vanadium complex of vanadium-enriched Cordyceps sinensis (VECS, which is beneficial in preventing depression in diabetes, and influences the long-term course of glycemic control. Vanadium compounds have the ability to imitate the action of insulin, and this mimicry may have further favorable effects on the level of treatment satisfaction and mood. C. sinensis has an antidepressant-like activity, and attenuates the diabetes-induced increase in blood glucose concentrations. We suggest that the VECS may be a potential strategy for contemporary treatment of depression and diabetes through the co-effect of C. sinensis and vanadium. The validity of the hypothesis can most simply be tested by examining blood glucose levels, and swimming and climbing behavior in streptozotocin-induced hyperglycemic rats.

  3. Nanoporous PdZr surface alloy as highly active non-platinum electrocatalyst toward oxygen reduction reaction with unique structure stability and methanol-tolerance

    Duan, Huimei; Xu, Caixia

    2016-06-01

    Nanoporous (NP) PdZr alloy with controllable bimetallic ratio is successfully fabricated by a simple dealloying method. By leaching out the more reactive Al from PdZrAl precursor alloy, NP-PdZr alloy with smaller ligament size was generated, characterized by the nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Upon voltammetric scan in acid solution, the dissolution of surface Zr atoms generates the highly active Pd-Zr surface alloy with a nearly pure Pd surface and Pd-Zr alloy core. The NP-Pd80Zr20 surface alloy exhibits markedly enhanced specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction (ORR) compared with NP-Pd and the state-of-the-art Pt/C catalysts. In addition, the NP-Pd80Zr20 surface alloy shows a better selectivity for ORR than methanol in the 0.1 M HClO4 and 0.1 M methanol mixed solution. X-ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd-O bond and improved ORR performances in turn depend on the downshifted d-band center of Pd due to the alloying Pd with Zr (20 at.%). The as-made NP-PdZr alloy holds prospective applications as a cathode electrocatalyst in fuel-cell-related technologies with the advantages of superior overall ORR performances, unique structure stability, and easy preparation.

  4. Discrepancy between theory and measurement of superconducting vanadium

    Zheng, X.H., E-mail: xhz@qub.ac.uk; Walmsley, D.G.

    2015-08-15

    Highlights: • First Born-von Karman analysis for vanadium phonons from synchrotron X-ray scattering. • Extracting vanadium atomic pseudo-potential from its spectral electrical resistivity. • First principles prediction of vanadium superconductivity. • Comparison with tube X-rays data and tantalum prediction. - Abstract: We have extracted consistent phonon dispersion information out of rather inconsistent vanadium X-ray scattering data from synchrotron and vacuum tube sources. With this and a new theoretical approach we have made firm predictions for the tunnelling conductance of superconducting vanadium; it is in unusually poor agreement with experimentally measured values. We argue that the problem lies in the experimental measurement rather than the theory. The preparation of a suitable high quality tunnel barrier on vanadium represents an outstanding challenge.

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

    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. PMID:21922094

  6. Structure and function of vanadium compounds in living organisms.

    Rehder, D

    1992-01-01

    Vanadium has been recognized as a metal of biological importance only recently. In this mini-review, its main functions uncovered during the past few years are addressed. These encompass (i) the regulation of phosphate metabolizing enzymes (which is exemplified for the inhibition of ribonucleases by vanadate), (ii) the halogenation of organic compounds by vanadate-dependent non-heme peroxidases from seaweeds, (iii) the reductive protonation of nitrogen (nitrogen fixation) by alternative, i.e. vanadium-containing, nitrogenases from N2-fixing bacteria, (iv) vanadium sequestering by sea squirts (ascidians), and (v) amavadine, a low molecular weight complex of V(IV) accumulated in the fly agaric and related toadstools. The function of vanadium, while still illusive in ascidians and toadstools, begins to be understood in vanadium-enzyme interaction. Investigations into the structure and function of model compounds play an increasingly important role in elucidating the biological significance of vanadium. PMID:1392470

  7. Aerobic oxidation reactions catalyzed by vanadium complexes of bis(phenolate) ligands.

    Zhang, Guoqi; Scott, Brian L; Wu, Ruilian; Silks, L A Pete; Hanson, Susan K

    2012-07-01

    Vanadium(V) complexes of the tridentate bis(phenolate)pyridine ligand H(2)BPP (H(2)BPP = 2,6-(HOC(6)H(2)-2,4-(t)Bu(2))(2)NC(5)H(3)) and the bis(phenolate)amine ligand H(2)BPA (H(2)BPA = N,N-bis(2-hydroxy-4,5-dimethylbenzyl)propylamine) have been synthesized and characterized. The ability of the complexes to mediate the oxidative C-C bond cleavage of pinacol was tested. Reaction of the complex (BPP)V(V)(O)(O(i)Pr) (4) with pinacol afforded the monomeric vanadium(IV) product (BPP)V(IV)(O)(HO(i)Pr) (6) and acetone. Vanadium(IV) complex 6 was oxidized rapidly by air at room temperature in the presence of NEt(3), yielding the vanadium(V) cis-dioxo complex [(BPP)V(V)(O)(2)]HNEt(3). Complex (BPA)V(V)(O)(O(i)Pr) (5) reacted with pinacol at room temperature, to afford acetone and the vanadium(IV) dimer [(BPA)V(IV)(O)(HO(i)Pr)](2). Complexes 4 and 5 were evaluated as catalysts for the aerobic oxidation of 4-methoxybenzyl alcohol and arylglycerol β-aryl ether lignin model compounds. Although both 4 and 5 catalyzed the aerobic oxidation of 4-methoxybenzyl alcohol, complex 4 was found to be a more active and robust catalyst for oxidation of the lignin model compounds. The catalytic activities and selectivities of the bis(phenolate) complexes are compared to previously reported catalysts. PMID:22708725

  8. Progress in the US program to develop low-activation structural materials for fusion

    It has long been recognized that attainment of the safety and environmental potential of fusion energy requires the successful development of low-activation materials for the first wall, blanket and other high heat flux structural components. Only a limited number of materials potentially possess the physical, mechanical and low-activation characteristics required for this application. The current US structural materials research effort is focused on three candidate materials: advanced ferritic steels, vanadium alloys, and silicon carbide composites. Recent progress has been made in understanding the response of these materials to neutron irradiation. (author)

  9. Progress in the U.S. program to develop low-activation structural materials for fusion

    It has long been recognized that attainment of the safety and environmental potential of fusion energy requires the successful development of low-activation materials for the first wall, blanket and other high heat flux structural components. Only a limited number of materials potentially possess the physical, mechanical and low-activation characteristics required for this application. The current U.S. structural materials research effort is focused on three candidate materials: advanced ferritic steels, vanadium alloys, and silicon carbide composites. Recent progress has been made in understanding the response of these materials to neutron irradiation. (author)

  10. Photochemical properties of acetyl-acetonate complex of vanadium (5)

    Photochemical properties of complex [VO(OH)(OCH3)(acac)] prepared by dissolving vanadium (5) acetylacetonate (acac) complex in methanol have been studied by spectrophotometric method. It has been ascertained that in the course of irradiation of methanol solution of the above-mentioned complex by UV photochemical reduction of vanadium (5) to vanadium (4) is observed. If irradiation is discontinued, the reaction occurs in the opposite direction

  11. Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

    The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

  12. Reaction of polyhalogenated unsaturated compounds with vanadium pentafluoride

    Terminal polyhalogenoalkenes are fluorinated by vanadium pentafluoride at -20 to -300C, whereas internal polyfluoroalkenes only react with vanadium pentafluoride when heated. 2-Chloropentafluoro-1,3-butadiene adds fluorine atoms predominantly at positions 1,4 under the influence of vanadium pentafluoride, but only the isomeric tetrafluorohexachlorobutanes are formed from perchloro-1,3-butadiene. Fluorination of perfluoroallylbenzene and perfluoro-β-methylstyrene takes place more rapidly in the side chain than in the aromatic ring

  13. Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

    HUANG Shun-hong; PENG Bing; YANG Zhi-hui; CHAI Li-yuan; ZHOU Li-cheng

    2009-01-01

    The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.

  14. EBSD analysis of (10–12) twinning activity in Mg–3Al–1Zn alloy during compression

    The (10–12) twinning activity of Mg–3Al–1Zn magnesium alloy during uniaxial compression at room temperature has been investigated by electron backscatter diffraction. The results indicated that the twinning activity was closely related with two angles: one was the angle between the c-axis and the compression direction and the other was the angle between the a-axis and the titling direction in the basal plane for a given relation between the c-axis and the compression direction. These two parameters can be used to explain which twinning variant will operate under the given strain path. For the grains containing a single (10–12) twinning variant, the (10–12) twinning variant occurred in a wide range of Schmid factor values (0 < Schmid factor < 0.5) and the Schmid factor rank of 1 or 2 was the most commonly observed. By contrast, for the grains containing two (10–12) twinning variants, the (10–12) twinning activity exhibited a stronger orientation dependence and the combinations of Schmid factor ranks 1–3 and 1–2 were the most commonly observed. - Highlights: • Twinning activity of AZ31 magnesium alloy was investigated by EBSD. • (10–12) twinning shows a strong orientation dependence. • Two angles can be used to explain which twin variant will operate

  15. Improving the Ethanol Oxidation Activity of Pt-Mn Alloys through the Use of Additives during Deposition

    Mohammadreza Zamanzad Ghavidel

    2015-06-01

    Full Text Available In this work, sodium citrate (SC was used as an additive to control the particle size and dispersion of Pt-Mn alloy nanoparticles deposited on a carbon support. SC was chosen, since it was the only additive tested that did not prevent Mn from co-depositing with Pt. The influence of solution pH during deposition and post-deposition heat treatment on the physical and electrochemical properties of the Pt-Mn alloy was examined. It was determined that careful control over pH is required, since above a pH of four, metal deposition was suppressed. Below pH 4, the presence of sodium citrate reduced the particle size and improved the particle dispersion. This also resulted in larger electrochemically-active surface areas and greater activity towards the ethanol oxidation reaction (EOR. Heat treatment of catalysts prepared using the SC additive led to a significant enhancement in EOR activity, eclipsing the highest activity of our best Pt-Mn/C prepared in the absence of SC. XRD studies verified the formation of the Pt-Mn intermetallic phase upon heat treatment. Furthermore, transmission electron microscopy studies revealed that catalysts prepared using the SC additive were more resistant to particle size growth during heat treatment.

  16. Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

    Armen Kvryan

    2016-04-01

    Full Text Available The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 M NaCl, corrosion occurred at the braze-316L interface preceded by preferential dissolution of the Cu-rich phase within the braze alloy. Braze corrosion was driven by galvanic couples between the braze alloys and stainless steel as well as between different phases within the braze microstructure. Microgalvanic corrosion between phases of the braze alloys was investigated via SKPFM to determine how corrosion of the brazed joints developed.

  17. Intermetallic Alloys as CO Electroreduction Catalysts-Role of Isolated Active Sites

    Karamad, Mohammadreza; Tripkovic, Vladimir; Rossmeisl, Jan

    2014-01-01

    potentially selective intermetallic surfaces on which CO can be reduced to methanol at potentials comparable to or even slightly positive than those for CO/CO2 reduction to methane on Cu. Common features shared by most of the selective alloys are single TM sites. The role of single sites is to block parasitic...

  18. Plasticity of V-Y alloy at high temperature

    Structural material components for fusion reactor must possess good characters, one of which is high plastic resistance under moderate temperature. Vanadium and yttrium metals are alloyed at a composition of V-1.6%wt Y and V-2.6%wt Y in order to develop the structural materials for fusion reactors. Alloying of the materials is conducted in a hot isostatic press machine at the temperature of 1173 °K and pressure of 200 MPa. Analytical measurements of the alloys using X-ray Diffractometry and Transmission Electron Microscopy (TEM) indicated that no new compounds were observed. Tensile test measurement at high temperatures using mini specimen tests showed that the presence of yttrium improved the plasticity of vanadium. (author)

  19. Multiply twinned AgNi alloy nanoparticles as highly active catalyst for multiple reduction and degradation reactions.

    Kumar, Mukesh; Deka, Sasanka

    2014-09-24

    Size dependent surface characteristics of nanoparticles lead to use of these nanomaterials in many technologically important fields, including the field of catalysis. Here Ag(1-x)Ni(x) bimetallic alloy nanoparticles have been developed having a 5-fold twinned morphology, which could be considered as an important alloy because of their excellent and unique catalytic and magnetic properties. Alloying between Ag and Ni atoms on a nanoscale has been confirmed with detailed X-ray diffraction, high resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and magnetization measurements. Although introduced for the first time as a catalyst due to having high active surface sites, the as-synthesized nanoparticles showed one of the best multiple catalytic activity in the industrially important (electro)-catalytic reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) to corresponding amines with noticeable reduced reaction time and increased rate constant without the use of any large area support. Additionally the same catalyst showed enhanced catalytic activity in degradation of environment polluting dye molecules. The highest ever activity parameter we report here for Ag0.6Ni0.4 composition is 156 s(-1)g(-1) with an apparent rate constant of 31.1 × 10(-3) s(-1) in a 4-NP reduction reaction where the amount of catalyst used was 0.2 mg and the time taken for complete conversion of 4-NP to 4-aminophenol was 60 s. Similarly, an incredible reaction rate constant (115 s(-1)) and activity parameter (576.6 s(-1)g(-1)) were observed for the catalytic degradation of methyl orange dye where 15 s is the maximum time for complete degradation of the dye molecules. The high catalytic performance of present AgNi alloy NPs over the other catalysts has been attributed to size, structural (twinned defect) and electronic effects. This study may lead to use of these bimetallic nanostructures with excellent recyclable catalytic

  20. Influence of bulk fibre properties of PAN-based carbon felts on their performance in vanadium redox flow batteries

    Schweiss, Rüdiger

    2015-03-01

    Polyacrylonitrile (PAN)-based carbon felts with different fibre properties were studied in terms of their suitability as porous flow-through electrode materials in all vanadium redox flow batteries. The crystallinity and their bulk hetero element content (in particular nitrogen) of the carbon fibres was shown to produce a significant effect on the electrocatalytical properties of the electrodes towards vanadium species. Similar effects were seen on the capacity losses associated with concomitant hydrogen evolution. Adjustments of fibre properties offer the potential of manufacturing improved electrode materials, potentially without additional steps such as surface activation or decoration with catalytically active species.