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Sample records for bronze sodium tungsten

  1. Understanding metal–insulator transition in sodium tungsten bronze

    Indian Academy of Sciences (India)

    Sanhita Paul; Satyabrata Raj

    2015-06-01

    We have carried out angle-resolved photoemission spectroscopy (ARPES) and spectromicroscopy studies to understand the metal–insulator transition (MIT) observed in sodium tungsten bronzes, NaWO3. The experimentally determined band structure is compared with the theoretical calculation based on full-potential linear augmented plane-wave method. It has been found that there is a good gross agreement between experiment and theory. ARPES spectra on the insulating sample show that the states near F are localized due to the random distribution of Na in WO3 lattice which causes strong disorder in the system. Our spectromicroscopy measurements on both insulating and metallic samples do not approve percolation model to explain MIT in NaWO3. Photoemission spectroscopy on metallic samples does not show any Na-induced impurity band (level), which was one of the models to explain MIT. Electron-like Fermi surface(s) has been found from our experiment for metallic samples at the (X) point which shows good agreement with band calculation.

  2. Sodium tungsten bronze thin films by rf sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Anderegg, J.W.

    1977-03-01

    Polycrystalline Na/sub x/WO/sub 3/ films were produced by rf sputtering. Films of low x-value resulted when co-sputtering WO/sub 3/ on a Na/sub 0.83/WO/sub 3/ target, and Na/sub 0/./sub 83/ on WO/sub 3/ target. Films of high x and of mixed phase were produced by sputtering a powder mixture of Na/sub 2/WO/sub 4/ and WO/sub 3/ on a tungsten target. Of the sputtering parameters studied, the substrate temperature is the most critical with temperatures above 500/sup 0/C producing films which were cubic in structure with only a small amount of Tetragonal I. The presence of oxygen up to 3 percent by volume had minimal effect on film quality or x-value. Auger, electron microprobe, SIMS, SEM, x-ray diffraction, and sheet resistivity techniques were used in characterizing these films. Resistivity of the films was a factor of 10 higher than the bulk crystalline data for Na/sub 0/./sub 83/WO/sub 3/.

  3. Corrosion evaluation of multi-pass welded nickel–aluminum bronze alloy in 3.5% sodium chloride solution: A restorative application of gas tungsten arc welding process

    International Nuclear Information System (INIS)

    Highlights: • Corrosion of GTA welded nickel–aluminum bronze (C95800) was studied. • Drastic microstructural changes occurred during the welding operations. • The β′ and α phases acts as anode and cathode, correspondingly, in weld region. • A few nanoamperes couple current was measured in ZRA test as galvanic corrosion. • Corrosion resistance of weld parts could not be weakened in marine environments. - Abstract: In this research, the corrosion behavior of a gas tungsten arc welded nickel–aluminum bronze (NAB) alloy is investigated by DC and AC electrochemical techniques in 3.5% sodium chloride solution. Regarding the electrochemical impedance spectroscopy and potentiodynamic results, uniform corrosion resistance of instantly immersed weld and base samples are almost analogous and increased (more in weld region) during the immersion times. Moreover, zero resistant ammeter results demonstrated that the few nanoampere galvanic currents are attributed to microstructural and morphological differences between these two regions. Therefore, the welding procedure could not deteriorate the general corrosion resistance of the restored damaged NAB parts operating in marine environments

  4. Novel polar dielectrics with the tetragonal tungsten bronze structure

    OpenAIRE

    Andrei ROTARU

    2013-01-01

    There is great interest in the development of new polar dielectric ceramics and multiferroic materials with new and improved properties. A family of tetragonal tungsten bronze (TTB) relaxors of composition Ba₆M³⁺Nb₉O₃₀ (M³⁺ = Ga³⁺, Sc³⁺ and In³⁺, and also their solid solutions) were studied in an attempt to understand their dielectric properties to enable design of novel polar TTB materials. A combination of electrical measurements (dielectric and impedance spectroscopy) and powder diffr...

  5. Structural Analysis and Electrical Property of Tungsten Bronze Prepared by Rare Earth Gaseous Permeation

    Institute of Scientific and Technical Information of China (English)

    李中华; 李昕; 陈刚; 苏铭汉; 韦永德

    2004-01-01

    The cubic sodium tungsten bronzes, NaxWO3(x=0.854 and 0.814)were prepared by rare earths gaseous permeation method. Structural analysis was carried out by Rietveld method from powder X-ray diffraction data. The X-ray diffraction profile calculated with cubic P32 models are in good agreement with the observed X-ray diffraction patterns. There is only a little difference in W-O bond and Na-O bond between Na0.854WO3 and Na0.814WO3. Conductivity measurements indicate that NaxWO3 show anomalous semiconducting behavior and percolation model was used to interpret it.

  6. Characterization and Photocatalytic Activity of KSr_2Nb_5O_(15) with Tungsten Bronze Structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaoke; LI Yiqiu; WANG Junting; TU Haibin; YU Xinyi

    2009-01-01

    Tungsten bronze(TB)type potassium strontium niobate KSr_2Nb_5O_(15) was prepared by solid-state reaction method,and was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and UV-vis diffuse spectrum.The photocatalyst shows high photocatalytic activity of photodegrading acid red G.The effects of photocatalyst dosage and initial concentration of acid red G on the photodegradation process were studied.The kinetics of photocatalytic degradation of acid red G by KSr_2Nb_5O_(15) catalyst follows the first order reaction.

  7. Studies of solids at low temperatures. Final scientific report. [Fluoro-tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Moulton, W.G.

    1970-10-01

    One of the primary objectives of this research has been to investigate the magnetic properties of materials which are likely to exhibit unusual magnetic transitions which may prove to be useful for microwave or switching devices. Experimental techniques used in this research included nuclear magnetic resonance, magnetic susceptibility measurements, optical spectroscopy, and electron spin resonance. A second goal was to develop relationships between magnetic properties and chemical bonding so that eventually magnetic properties could be predicted from the structure of a compound. Another objective of this research was to investigate the possibility of superconductivity in the fluoro-tungsten bronzes. Forty-two of these compounds were synthesized and all were found to have superconducting transition temperatures between one and one half degrees and five degrees kelvin. Relationships between the critical fields and the transition temperature and the composition have been established.

  8. Origin of ferroelectric polarization in tetragonal tungsten-bronze-type oxides

    Science.gov (United States)

    Olsen, Gerhard Henning; Aschauer, Ulrich; Spaldin, Nicola A.; Selbach, Sverre Magnus; Grande, Tor

    2016-05-01

    The origin of ferroelectric polarization in tetragonal tungsten-bronze- (TTB-) type oxide strontium barium niobate (SBN) is investigated using first-principles density functional calculations. We study in particular the relationship between the polarization and the cation and vacancy ordering on alkali-earth metal lattice sites. Lattice dynamical calculations for paraelectric structures demonstrate that all cation configurations that can be accommodated in a 1 ×1 ×2 supercell result in a single unstable polar phonon, composed primarily of relative Nb-O displacements along the polar axis, as their dominant instability. The majority of the configurations also have a second octahedral tilt-mode instability which couples weakly to the polar mode. The existence of the tilt mode is strongly dependent on the local cation ordering, consistent with the fact that it is not found experimentally. Our results suggest that ferroelectricity in the SBN system is driven by a conventional second-order Jahn-Teller mechanism caused by the d0 Nb5 + cations, and demonstrate the strong influence of the size of Sr and Ba on the lattice distortions associated with polarization and octahedral tilting. Finally, we suggest a mechanism for the relaxor behavior in Sr-rich SBN based on Sr displacement inside pentagonal channels in the TTB structure.

  9. Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Najdoski, Metodija, E-mail: metonajd@yahoo.com [Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, POB 162, Arhimedova 5, 1000 Skopje, Republic of Macedonia (Macedonia, The Former Yugoslav Republic of); Koleva, Violeta [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Demiri, Sani [Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius University, POB 162, Arhimedova 5, 1000 Skopje, Republic of Macedonia (Macedonia, The Former Yugoslav Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We report a new chemical bath method for the deposition of vanadium bronze thin films. Black-Right-Pointing-Pointer The films are phase mixture of NaV{sub 6}O{sub 15} and Na{sub 1.1}V{sub 3}O{sub 7.9} with 10.58% lattice water. Black-Right-Pointing-Pointer The as-deposited vanadium bronze films exhibit two-step electrochromism. Black-Right-Pointing-Pointer They change their yellow-orange color to green and then from green to blue color. Black-Right-Pointing-Pointer The method allows the preparation of films on substrates with low melting point. -- Abstract: Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium-vanadium solution (1:1) at 75 Degree-Sign C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM-EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV{sub 6}O{sub 15} (predominant component) and Na{sub 1.1}V{sub 3}O{sub 7.9} with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 Degree-Sign C changes the composition, optical and electrochemical properties.

  10. Tungsten bronze-based nuclear waste form ceramics. Part 1. Conversion of microporous tungstates to leach resistant ceramics

    Science.gov (United States)

    Luca, Vittorio; Griffith, Christopher S.; Drabarek, Elizabeth; Chronis, Harriet

    2006-11-01

    The effective immobilization of Cs + and/or Sr 2+ sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials has been achieved by heating in air at temperatures in the range 500-1000 °C. Crystalline powdered HTB materials formed by heating at 800 °C displayed leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. If the Cs-loaded HTB sorbents were pressed into pellets prior to calcination, ceramic monoliths could be prepared with negligible Cs volatilization losses. Heating to temperatures in excess of 1250 °C under dynamic air flow resulted in the melting of the sorbent to form phase assemblages consisting of millimetre-sized crystals of bronzoid phases. Up to 5 wt% mass loss was observed for small scale samples of melted materials under dynamic air flow. Both the calcined and melted bronzoid waste forms are multiphase ceramics in which Cs + remains bound within, and appears to stabilize, the hexagonal bronze phase, even after complete melting at 1300 °C. The leachability of Sr from the phases prepared by heating appears to be somewhat worse than that of Cs. Saturation of the HTB adsorbents with lanthanide elements (Nd, La, Ce) gave rise to cubic bronze phases in which we propose that the lanthanides substitute at the tungsten or molybdenum sites rather than the tunnel positions. The lanthanides were rather easily leached from the calcined phases in 0.1 M HNO 3 at 150 °C.

  11. Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

    International Nuclear Information System (INIS)

    Highlights: ► We report a new chemical bath method for the deposition of vanadium bronze thin films. ► The films are phase mixture of NaV6O15 and Na1.1V3O7.9 with 10.58% lattice water. ► The as-deposited vanadium bronze films exhibit two-step electrochromism. ► They change their yellow-orange color to green and then from green to blue color. ► The method allows the preparation of films on substrates with low melting point. -- Abstract: Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium–vanadium solution (1:1) at 75 °C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM–EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV6O15 (predominant component) and Na1.1V3O7.9 with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 °C changes the composition, optical and electrochemical properties

  12. The preparation and chemical reaction kinetics of tungsten bronze thin films and nitrobenzene with and without a catalyst

    Science.gov (United States)

    Materer, Nicholas F.; Apblett, Allen; Kadossov, Evgueni B.; Khan, Kashif Rashid; Casper, Walter; Hays, Kevin; Shams, Eman F.

    2016-06-01

    Microcrystalline tungsten bronze thin films were prepared using wet chemical techniques to reduce a tungsten oxide thin film that was prepared by thermal oxidation of a sputter deposited tungsten metal film on a quartz substrate. The crystallinity of these films was determined by X-ray diffraction and the surface was characterized by X-ray and Ultra-Violet Photoelectron spectroscopy. The total amount of hydrogen incorporated in the film was monitored using absorbance spectroscopy at 900 nm. The oxidation kinetics of the film and the hydrogenation of nitrobenzene in hexane were measured as a function of film thickness. A satisfactory fit of the resulting kinetics was obtained using a model that involves two simultaneous processes. The first one is the proton diffusion from the bulk of the film to the surface, and the second is a reaction of the surface protons with the oxidants. Finally, the dependence of the reaction rates on the presence of catalytic amounts of first row transition metals on the surface of the film was explored.

  13. Solvothermal Synthesis of Caesium Tungsten Bronze in the Presence of Various Organic Acids and Its NIR Absorption Properties

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Chongshen; Yin, Shu; Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); Adachi, Kenji; Chonan, Takeshi, E-mail: bigguop@mail.tagen.tohoku.ac.jp [Ichikawa Research Laboratory, Sumitomo Metal Mining Co., Ltd (Japan)

    2011-10-29

    Nanoparticles of caesium tungsten bronze were successfully synthesized by solvothermal reactions in ethanol with the introduction of different organic fatty acids with various carbon numbers of 1 to 5. Compared to the sample prepared in pure ethanol, the samples obtained by mixed solvent of ethanol and fatty acids showed higher production yield, smaller particle size, more uniform particles size distribution and higher Cs/W atomic ratio. In addition, all of samples obtained using acids-ethanol mixed solvent exhibited higher visible light transmittance and greater NIR absorption performance, indicating the potential application for smart window and heat-ray shielding materials. The addition of acetic acid showed the best performance to facilitate the formation of well dispersed Cs{sub x}WO{sub 3} regular nanorods, leading to its excellent optical properties.

  14. A Facile One-Step Solvothermal Synthesis and Electrical Properties of Reduced Graphene Oxide/Rod-Shaped Potassium Tungsten Bronze Nanocomposite.

    Science.gov (United States)

    Liu, Bin; Yin, Shu; Wang, Yuhua; Guo, Chongshen; Wu, Xiaoyong; Dong, Qiang; Kobayashi, Makoto; Kakihana, Masato; Sato, Tsugio

    2015-09-01

    Reduced graphene oxide (rGO)/rod-shaped potassium tungsten bronze nanocomposites with the different ratio were successfully synthesized by solvothermal reaction and followed by the reduction in H2(5 vol.%)/N2 atmosphere at 550 degrees C. The coupled samples showed excellent shielding ability of NIR light as well as certain visible lights transparency. The synergistic effects could be observed in the composites, i.e., when 15 wt% and 20 wt% of rGO which was fabricated by chemical reduction of graphene oxide, were composed into K(x)WO3, the composite showed the higher electrical conductivity than those of rGO and potassium tungsten bronze. PMID:26716327

  15. On the nature of phase transitions in the tetragonal tungsten bronze GdK2Nb5O15 ceramics

    International Nuclear Information System (INIS)

    Phase transitions in gadolinium potassium niobate GdK2Nb5O15 (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at Tc1 = 238 °C and Tc2 = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T0. The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence

  16. Dielectric relaxation and ac conductivity of sodium tungsten phosphate glasses

    Indian Academy of Sciences (India)

    B Singh; P S Tarsikka; L Singh

    2002-10-01

    Studies of dielectric relaxation and ac conductivity have been made on three samples of sodium tungsten phosphate glasses over a temperature range of 77–420 K. Complex relative permittivity data have been analyzed using dielectric modulus approach. Conductivity relaxation frequency increases with the increase of temperature. Activation energy for conductivity relaxation has also been evaluated. Measured ac conductivity (m()) has been found to be higher than dc at low temperatures whereas at high temperature m() becomes equal to dc at all frequencies. The ac conductivity obeys the relation ac() = A over a considerable range of low temperatures. Values of exponent are nearly equal to unity at about 78 K and the values decrease non-linearly with the increase of temperature. Values of the number density of states at Fermi level ((F)) have been evaluated at 80 K assuming values of electron wave function decay constant to be 0.5 (Å)-1. Values of (F) have the order 1020 which are well within the range suggested for localized states. Present values of (F) are smaller than those for tungsten phosphate glasses.

  17. Behavior of the monophosphate tungsten bronzes (PO{sub 2}){sub 4}(WO{sub 3}){sub 2m} (m=4 and 6) in electrochemical lithium insertion

    Energy Technology Data Exchange (ETDEWEB)

    Longoria Rodriguez, F.E.; Martinez-de la Cruz, A.; Lopez Cuellar, E. [Division de Estudios de Posgrado, Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, NL (Mexico)

    2006-10-06

    The electrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO{sub 2}){sub 4}(WO{sub 3}){sub 2m}, where m=4 and 6. Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostatic intermittent technique, the different processes which take place in the cathode during the discharge of the cell were analysed. The nature of the bronzes Li{sub x}(PO{sub 2}){sub 4}(WO{sub 3}){sub 2m} formed was determined by in situ X-ray diffraction experiments. These results have allowed establishment of a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion. Measurements of resistivity showed that upon lithium insertion, the metallic pristine oxides become insulating. (author)

  18. Thermal Expansion and Second Harmonic Generation Response of the Tungsten Bronze Pb2AgNb5O15.

    Science.gov (United States)

    Lin, Kun; Gong, Pifu; Sun, Jing; Ma, Hongqiang; Wang, You; You, Li; Deng, Jinxia; Chen, Jun; Lin, Zheshuai; Kato, Kenichi; Wu, Hui; Huang, Qingzhen; Xing, Xianran

    2016-03-21

    The incorporation of transition metal element Ag was performed to explore negative thermal expansion (NTE) materials with tetragonal tungsten bronze (TTB) structures. In this study, the structure and thermal expansion behaviors of a polar TTB oxide, Pb2AgNb5O15 (PAN), were systematically investigated by high-resolution synchrotron powder diffraction, high-resolution neutron powder diffraction, transmission electron microscope (TEM), and high-temperature X-ray diffractions. The TEM and Rietveld refinements revealed that the compound PAN displays (√2a(TTB), √2b(TTB), 2c(TTB))-type superstructure. This superstructure within the a-b plane is caused by the ordering of A-site cations, while the doubling of the c axis is mainly induced by a slight tilt distortion of the NbO6 octahedra. The transition metal Ag has larger spontaneous polarization displacements than Pb, but the Pb-O covalence seems to be weakened compared to the potassium counterpart Pb2KNb5O15 (PKN), which may account for the similar Curie temperature and uniaxial NTE behavior for PAN and PKN. Powder second harmonic generation (SHG) measurement indicates that PAN displays a moderate SHG response of ∼0.2 × LiNbO3 (or ∼100 × α-SiO2) under 1064 nm laser radiation. The magnitudes of the local dipole moments in NbO6 and PbOx polyhedra were quantified using bond-valence approach. We show that the SHG response stems from the superposition of dipole moments of both the PbO(x) and NbO6 polyhedra. PMID:26928907

  19. Crystallography properties of solid solution of NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}s}tructure of tetragonal tungsten bronze; Propriedades cristalograficas da solucao de NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}} de estrutura tetragonal tungstenio bronze

    Energy Technology Data Exchange (ETDEWEB)

    Polini, C.; Dantas, S.A.; Mikaro, C.; Lima, A.R.F.; Nobre, M.A.L.; Lanfredi, S. [Universidade Estadual Paulista (LaCCeF/UNESP), Presidente Prudente, SP (Brazil). Dept. de Fisica, Quimica e Biologia. Lab. de Compositos e Ceramicas Funcionais

    2009-07-01

    In this work was investigated the crystallographic characterization of single phase and nanometric powders of sodium strontium niobate doped with nickel, with NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}} stoichiometry, prepared by conventional route from mechanical mixture of oxides / carbonates using the high energy ball milling. The optimization of the parameters as time and calcination temperature for the preparation of the NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}} solid solution were monitored by X-ray diffraction, using the Rietveld method. The NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}} single phase powders with tetragonal tungsten bronze type structure were obtained with crystallite size at around 30 nm. From crystallographic parameters was constructed the unitary cellule of the NaSr{sub 2}(NiNb{sub 4})O{sub 15-{delta}} using the CaRIne Crystallography 3.1 program. The occupation of sites by the Na{sup +} and Sr{sup 2+} cations and the interatomic distances between nickel and niobium atoms were determined. Changes in structural parameters of sodium strontium niobate by addition of nickel are discussed. (author)

  20. The crystal chemistry of the tetragonal tungsten-bronze: Ba6FeNb9O30

    International Nuclear Information System (INIS)

    Solid state reaction of BaCO3, FeC2O4 x 2 H2O and Nb2O5 gave single crystals of Ba6FeNb9O30. The crystal strucuture was solved by X-ray investigations (a = 12.597, c = 3.990 Ao, space group P4 bm - C4v2, Z = 1). Ba6FeNb9O30 crystallyzes in the tetragonal bronze type with a statistical distribution of Fe3+ and Nb5+ in the octahedral framework. The anisotropic temperature factors of barium are discussed with respect to the oxygen coordination. (Author)

  1. Behavior of the monophosphate tungsten bronzes (PO{sub 2}){sub 4}(WO{sub 3}){sub 2m} (m = 7 and 8) in the course of electrochemical lithium insertion

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-de la Cruz, A. [Division de Estudios de Posgrado, Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451, San Nicolas de los Garza, N.L. (Mexico); Longoria Rodriguez, F.E.; Gonzalez, Lucy T. [Departamento de Quimica, Unidad de Cursos Basicos, Nucleo Monagas, UDO, Av Universidad Los Guaritos, Maturin, Monagas (Venezuela); Torres-Martinez, Leticia M. [Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Av Universidad s/n, San Nicolas de los Garza, N.L. (Mexico)

    2007-07-10

    The electrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO{sub 2}){sub 4}(WO{sub 3}){sub 2m}, where m = 7 and 8. Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostatic intermittent technique the different processes which take place in the cathode during the discharge of the cell were analyzed. The nature of the bronzes Li{sub x}(PO{sub 2}){sub 4}(WO{sub 3}){sub 2m} formed was determined by in situ X-ray diffraction experiments. These results have allowed establishing a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion. (author)

  2. On the nature of phase transitions in the tetragonal tungsten bronze GdK{sub 2}Nb{sub 5}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Gagou, Y.; Lukyanchuk, I.; El Marssi, M., E-mail: mimoun.elmarssi@u-picardie.fr [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Amira, Y. [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Mezzane, D. [Laboratoire de la Matière Condensée et Nanostructures, FSTG, Université Cadi Ayyad Marrakech, Maroc (Morocco); Courty, M.; Masquelier, C. [Laboratoire de Réactivité et Chimie des Solides, UMR 7314, Université de Picardie Jules Verne, Pôle Scientifique, 33 rue Saint-Leu, 80039 Amiens Cedex 1 (France); Yuzyuk, Yu. I. [Faculty of Physics, Southern Federal University, 5, Zorge Str. Rostov-on-Don 344090 (Russian Federation)

    2014-02-14

    Phase transitions in gadolinium potassium niobate GdK{sub 2}Nb{sub 5}O{sub 15} (GKN) ceramics have been investigated by x-ray diffraction, dielectric susceptibility, differential scanning calorimetry, and Raman scattering. The results of our complementary studies show that GKN exhibits two phase transitions at T{sub c1} = 238 °C and T{sub c2} = 375 °C attributed to the ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) phase transitions. According to the x-ray diffraction analysis, the FE and PE phases were refined in the polar P4bm and centrosymmetric P4/mbm space groups. For the intermediate phase, the structure is refined in the space group P4nc with doubling of the c unit cell parameter, which is compatible with an AFE phase. This result was confirmed by Raman spectroscopy since new low-frequency lines are activated in the AFE phase due to the Brillouin zone-folding effect, typical for the modulated phases. The presence of the AFE phase between the FE and PE phases and the complex nature of tetragonal tungsten bronze crystal structure can explain the large thermal hysteresis observed at the FE-AFE transition between heating and cooling cycle and the strong depression of the Curie-Weiss temperature T{sub 0}. The semi-phenomenological Ising-like model based on the obtained experimental data is proposed to account for the observed FE-AFE-PE transition sequence.

  3. Tungsten bronze-based nuclear waste form ceramics. Part 2: Conversion of granular microporous tungstate polyacrylonitrile (PAN) composite adsorbents to leach resistant ceramics

    Science.gov (United States)

    Griffith, Christopher S.; Sebesta, Ferdinand; Hanna, John V.; Yee, Patrick; Drabarek, Elizabeth; Smith, Mark E.; Luca, Vittorio

    2006-11-01

    Conversion of a granular molybdenum-doped, hexagonal tungsten bronze (MoW-HTB)-polyacrylonitrile (PAN) composite adsorbent to a leach resistant ceramic waste form capable of immobilizing adsorbed Cs + and Sr 2+ has been achieved by heating in air at temperatures in the range 600-1200 °C. Thermal treatment of the Cs- and Sr-loaded composite material at 1000 °C was sufficient to invoke a 60% reduction in volume of the composite while still retaining its spherical morphology. Cs-133 MAS NMR studies of this sample suite at 9.4 T and 14.1 T showed that multiple Cs sites are present throughout the entire thermal treatment range. Scanning electron microscopy investigations of the phase assemblages resulting from thermal treatment demonstrated that the full complement of Cs, and the majority of Sr, partitions into HTB phases (A 0.16-0.3MO 3; A = Cs +, Sr 2+ and Na +; M = Mo, W). The potentially reducing conditions resulting from the removal of the PAN matrix or the presence of high concentrations of Na + relative to either Cs + or Sr 2+ does not retard the formation of the high temperature HTB phases. The fraction of Cs + and Sr 2+ leached from the tungstate phase assemblages was superior or comparable with cesium hollandite (Cs 0.8Ba 0.4Ti 8O 18; f = ≈8 × 10 -5; rate = <1.2 × 10 -4 g/m 2/day) and strontium titanate (SrTiO 3; f = 3.1 × 10 -3; rate = 2.63 × 10 -4 g/m 2/day), respectively, using a modified PCT test in Millipore water at 90 °C. Furthermore, where aggressive leaching conditions were employed (0.1 M HNO 3; 150 °C; 4 days), the tungstate phase assemblages displayed leach resistance almost two orders of magnitude greater than the reference phases.

  4. Tungsten bronze-based nuclear waste form ceramics. Part 2: Conversion of granular microporous tungstate-polyacrylonitrile (PAN) composite adsorbents to leach resistant ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Christopher S. [Australian Nuclear Science and Technology Organisation, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234 (Australia); Sebesta, Ferdinand [Czech Technical University in Prague, Department of Nuclear Chemistry, Brehova 7, 115 19 Prague 1 (Czech Republic); Hanna, John V. [Australian Nuclear Science and Technology Organisation, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234 (Australia); Yee, Patrick [Australian Nuclear Science and Technology Organisation, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234 (Australia); Drabarek, Elizabeth [Australian Nuclear Science and Technology Organisation, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234 (Australia); Smith, Mark E. [Department of Physics, University of Warwick, Gibbett Hill Road, Coventry CV47AL (United Kingdom); Luca, Vittorio [Australian Nuclear Science and Technology Organisation, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234 (Australia)]. E-mail: vlu@ansto.gov.au

    2006-11-30

    Conversion of a granular molybdenum-doped, hexagonal tungsten bronze (MoW-HTB)-polyacrylonitrile (PAN) composite adsorbent to a leach resistant ceramic waste form capable of immobilizing adsorbed Cs{sup +} and Sr{sup 2+} has been achieved by heating in air at temperatures in the range 600-1200 deg. C. Thermal treatment of the Cs- and Sr-loaded composite material at 1000 deg. C was sufficient to invoke a 60% reduction in volume of the composite while still retaining its spherical morphology. Cs-133 MAS NMR studies of this sample suite at 9.4 T and 14.1 T showed that multiple Cs sites are present throughout the entire thermal treatment range. Scanning electron microscopy investigations of the phase assemblages resulting from thermal treatment demonstrated that the full complement of Cs, and the majority of Sr, partitions into HTB phases (A{sub 0.16-0.3}MO{sub 3}; A = Cs{sup +}, Sr{sup 2+} and Na{sup +}; M = Mo, W). The potentially reducing conditions resulting from the removal of the PAN matrix or the presence of high concentrations of Na{sup +} relative to either Cs{sup +} or Sr{sup 2+} does not retard the formation of the high temperature HTB phases. The fraction of Cs{sup +} and Sr{sup 2+} leached from the tungstate phase assemblages was superior or comparable with cesium hollandite (Cs{sub 0.8}Ba{sub 0.4}Ti{sub 8}O{sub 18}; f = {approx}8 x 10{sup -5}; rate = <1.2 x 10{sup -4} g/m{sup 2}/day) and strontium titanate (SrTiO{sub 3}; f = 3.1 x 10{sup -3}; rate = 2.63 x 10{sup -4} g/m{sup 2}/day), respectively, using a modified PCT test in Millipore water at 90 deg. C. Furthermore, where aggressive leaching conditions were employed (0.1 M HNO{sub 3}; 150 deg. C; 4 days), the tungstate phase assemblages displayed leach resistance almost two orders of magnitude greater than the reference phases.

  5. Structure and dielectric properties of Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} tungsten bronze ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Yan-Qing; Yu, Yuan [College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19(A) Yu Quan Road, Beijing 100049 (China); Hao, Yong-Mei, E-mail: ymhao@ucas.ac.cn [College of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19(A) Yu Quan Road, Beijing 100049 (China); Dong, Su-Ying; Yang, Yi-Wen [Beijing National Day School, 66 Yu Quan Road, Beijing 100039 (China)

    2013-05-15

    Highlights: ► Tetragonal tungsten bronze ceramic Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} was prepared. ► Titanium was replaced by copper in M{sub 5}RTi{sub 3}Nb{sub 7}O{sub 30} for the first time. ► Detailed structural information was retrieved by Rietveld refinement. ► An obvious relaxor-like dielectric behavior was observed in this ceramic, ion disorders in A1 and B sites contribute to this behavior. - Abstract: A new type of tungsten bronze ceramic Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} has been prepared by a conventional solid-state reaction technique. Its structural, dielectric properties were investigated. Rietveld analysis shows that Ba{sub 5}NdCu{sub 1.5}Nb{sub 8.5}O{sub 30−δ} has a single-phase tetragonal (space group P4bm and lattice constants a = b = 12.4961(4) Å, c = 3.9426(8) Å, V = 615.66(4) Å{sup 3}) tungsten bronze structure. The occupations of sites A and B are quite interesting. A1 sites are fully disordered occupied by Ba ions and Nd ions and A2 sites for Ba ions only, while B-sites are equal for both Cu and Nb ions to occupy. This material exhibits an obvious relaxation behavior in the 213–573 K temperature range. The dielectric constants have been fitted by the modified Curie–Weiss law and all the estimated γ values are close to 2, confirming the typical relaxor ferroelectric behavior. The disorders of Ba{sup 2+} or Nd{sup 3+} in A1 sites and Nb{sup 5+}, Cu{sup 2+} in B sites induced by the oxygen vacancies may contribute to this dielectric behavior.

  6. Ion-exchange equilibria of tungsten in the ionite-sodium sulfate sulfuric acid solution system

    International Nuclear Information System (INIS)

    Ion-exchange equilibrium in the system macroporous ionite-Na2WO4-Na2SO4-H2O(H2SO4) are studied by the methods of IR- and absorption spectroscopy, electron microscopy and mercury porometry to develop methods for tungsten selective extraction from solutions mentioned. It is ascertained that amine-containing macroporous anionites features a high exchange capacity towards tungsten ions in sulfate solutions at pH 2.5-5.5. The anionites permit a complete separation of tungsten ions from sulfate ions and preparation of pure tungsten salts

  7. Bronze Saddlery

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    A number of relics were unearthed when Chinese archaeologists discovered a group of graves in Liaoning Province in April, 1976. Dating back to the Spring and Autumn Period and the Warring States Period, the tombs contained many bronze ornaments for saddles that featured such animals as frogs, snakes, tigers and rabbits.

  8. Adsorption of Lanthanides by A{sub y}Mo{sub x}W{sub 1-x}O{sub 3} Hexagonal Tungsten Bronzes and Prospects for their Potential Use as Recyclable Inert Matrix Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio; Yang, Bin; Yaman, Ilkay; Griffith, Christopher S.; Scales, Nicholas; Sizgek, Erden [Australian Nuclear Science and Technology Organisation (ANSTO), Institute of Materials Engineering, New Illawarra Road, Lucas Heights, New South Wales, 2234 (Australia)

    2008-07-01

    The hexagonal tungsten bronze (HTB) based adsorbents of general formula A{sub y}M{sub x}W{sub 1-x}O{sub 3}.ZH{sub 2}O have been a particular focus of attention in our laboratory for some time. In the context of a potential partition and transmutation strategy our interest in these HTB materials has been stimulated by their particularly high affinity for lanthanide (LN) and minor actinide (MA). In addition to partitioning operations the materials can also be contemplated for mop-up and decontamination applications. With Cs{sup +} as the target species, HTBs can be converted to very effective waste form materials with performances comparable to the best Cs-containing ceramics such as hollandite. However, their excellent affinity for LNs and MAs suggest their use for MA recycling. When granular variants of the HTB adsorbents are loaded with LNs and are heated in air to relatively modest temperatures these elements preferentially partition into relatively soluble phases imbedded within a durable WO{sub 3} matrix. Since the LN-containing phase is relatively soluble, efficient recovery of the LNs or potentially MAs is feasible. This, together with potentially favorable irradiation properties, suggests they may have uses as recyclable inert matrix fuels. In this communication, we discuss LN and MA adsorption and thermal properties of HTB materials with variable x, as well as resistance to {gamma}-radiation and heavy ion bombardment. Finally, recoverability of the LNs is considered. (authors)

  9. Direct determination of sodium, potassium, chromium and vanadium in biodiesel fuel by tungsten coil atomic emission spectrometry

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •Direct analysis of biodiesel on a tungsten coil atomizer. •Determination of Na, K, Cr and V by tungsten coil atomic emission spectrometry. •Sample dilution with methanol or ethanol. •Ten-microliter sample aliquots and limits of detection between 20 and 90 μg kg−1. •Low consumption of reagents, samples and gases in a 140 s per run procedure. -- Abstract: High levels of sodium and potassium can be present in biodiesel fuel and contribute to corrosion, reduced performance and shorter engine lifetime. On the other hand, trace amounts of chromium and vanadium can increase the emission of pollutants during biodiesel combustion. Sample viscosity, immiscibility with aqueous solutions and high carbon content can compromise biodiesel analyzes. In this work, tungsten filaments extracted from microscope light bulbs are used to successively decompose biodiesel's organic matrix, and atomize and excite the analytes to determine sodium, potassium, chromium and vanadium by tungsten coil atomic emission spectrometry (WCAES). No sample preparation other than simple dilution in methanol or ethanol is required. Direct analysis of 10-μL sample aliquots using heating cycles with less than 150 s results in limits of detection (LOD) as low as 20, 70, 70 and 90 μg kg−1 for Na, K, Cr and V, respectively. The procedure's accuracy is checked by determining Na and K in a biodiesel reference sample and carrying out spike experiments for Cr and V. No statistically significant differences were observed between reference and determined values for all analytes at a 95% confidence level. The procedure was applied to three different biodiesel samples and concentrations between 6.08 and 95.6 mg kg−1 for Na and K, and between 0.22 and 0.43 mg kg−1 for V were obtained. The procedure is simple, fast and environmentally friendly. Small volumes of reagents, samples and gases are used and no residues are generated. Powers of detection are comparable to

  10. Direct determination of sodium, potassium, chromium and vanadium in biodiesel fuel by tungsten coil atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dancsak, Stacia E. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Silva, Sidnei G.; Nóbrega, Joaquim A. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, São Carlos, SP (Brazil); Jones, Bradley T. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Donati, George L., E-mail: georgedonati@yahoo.com.br [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States)

    2014-01-02

    Graphical abstract: -- Highlights: •Direct analysis of biodiesel on a tungsten coil atomizer. •Determination of Na, K, Cr and V by tungsten coil atomic emission spectrometry. •Sample dilution with methanol or ethanol. •Ten-microliter sample aliquots and limits of detection between 20 and 90 μg kg{sup −1}. •Low consumption of reagents, samples and gases in a 140 s per run procedure. -- Abstract: High levels of sodium and potassium can be present in biodiesel fuel and contribute to corrosion, reduced performance and shorter engine lifetime. On the other hand, trace amounts of chromium and vanadium can increase the emission of pollutants during biodiesel combustion. Sample viscosity, immiscibility with aqueous solutions and high carbon content can compromise biodiesel analyzes. In this work, tungsten filaments extracted from microscope light bulbs are used to successively decompose biodiesel's organic matrix, and atomize and excite the analytes to determine sodium, potassium, chromium and vanadium by tungsten coil atomic emission spectrometry (WCAES). No sample preparation other than simple dilution in methanol or ethanol is required. Direct analysis of 10-μL sample aliquots using heating cycles with less than 150 s results in limits of detection (LOD) as low as 20, 70, 70 and 90 μg kg{sup −1} for Na, K, Cr and V, respectively. The procedure's accuracy is checked by determining Na and K in a biodiesel reference sample and carrying out spike experiments for Cr and V. No statistically significant differences were observed between reference and determined values for all analytes at a 95% confidence level. The procedure was applied to three different biodiesel samples and concentrations between 6.08 and 95.6 mg kg{sup −1} for Na and K, and between 0.22 and 0.43 mg kg{sup −1} for V were obtained. The procedure is simple, fast and environmentally friendly. Small volumes of reagents, samples and gases are used and no residues are generated

  11. Tungsten bronze-based nuclear waste form ceramics. Part 3: The system Cs 0.3M xW 1- xO 3 for the immobilization of radio cesium

    Science.gov (United States)

    Luca, Vittorio; Drabarek, Elizabeth; Chronis, Harriet; McLeod, Terry

    2006-11-01

    Previous studies in this series have indicated that Cs- and Sr-loaded Mo-doped hexagonal tungsten bronze (MoW-HTB) oxides, either in the form of fine grained powders, or as composite granules, can be converted to leach resistant ceramics at modest temperatures in the range 600-1200 °C. In the present study it has been shown that such waste form ceramics can also be readily prepared through very simple conventional routes involving the blending of cesium nitrate with tungstic acid and other oxide components followed by heating in air. The phase chemistry resulting from the blending of these oxides has been explored. In the Cs 0.3M xW 1- xO 3 compositional system where x = Ti, Zr, Nb and Ta the solid solution limit has been found to be where x = 0.2. For all values of x between 0 and 0.2 mixed phase materials of HTB and WO 3 were obtained and Cs was found associated with HTB phases that are both rich and depleted in M element. At temperatures above about 1000 °C, phase pure HTB compounds in the space group P63/ mcm were obtained. Even when x greatly exceeds 0.2, the additional oxide content did not interfere with the formation of the HTB phase. Durability of the Cs 0.3M xW 1- xO 3 compositions as gauged by the fractional Cs loss in de-mineralized water was lowest when M = Ti and Nb, and greatest when M = Zr. From these results the durability appears intimately linked with the unit cell a-dimension which in turn varies with M cation radius.

  12. Effect of lead fluoride incorporation on the structure and luminescence properties of tungsten sodium phosphate glasses

    Science.gov (United States)

    Nardi, Rachel Prado Russo Delorenzo; Braz, Celso Eduardo; de Camargo, Andrea S. S.; Ribeiro, Sidney J. L.; Rocha, Lucas A.; Cassanjes, Fábia Castro; Poirier, Gael

    2015-11-01

    Tungsten phosphate glasses are known to be promising materials for several applications in optics such as non linear optical properties, lower phonon energy or photochromic effects related with tungsten oxide incorporation inside the phosphate network. In this study, lead fluoride has been incorporated in a 60NaPO3-40WO3 glass composition according to the ternary molar compositions (100 - x)[0.6NaPO3-0.4WO3]-xPbF2 with x varying from 0 to 60 mol%. The structural changes as a function of composition were investigated by thermal analysis, UV-visible absorption, Raman spectroscopy, X-ray diffraction of the crystallized samples, and Eu3+ emission in the visible. While DSC analyzes points out a strong decrease in the glass network connectivity and higher crystallization tendency with increasing PbF2 contents, Raman spectra clearly identify a progressive incorporation of PbF2 in the phosphate network with the formation of terminal Psbnd F and Wsbnd F bonds. These results are also in agreement with the crystallization of β-PbF2 observed for the most lead fluoride concentrated samples. Investigation of Eu3+ emission data in the visible showed longer 5D0 excited state lifetime values and higher quantum efficiencies. These results are discussed in terms of the assumption of higher local symmetry around Eu3+ with increasing PbF2 contents.

  13. Neutron diffraction study of the atomic structure of cubic sodium-tungsten bronze (Na0.69WO3) single crystal

    International Nuclear Information System (INIS)

    The atomic structure of a single crystal of one of four Na0.69WO3 phases, which exist below 293 K, has been refined from neutron diffraction data (WWR-c reactor at the Karpov Institute of Physical Chemistry, Obninsk Branch; λ = 1.168 Å; λ/2 contribution −1). The Na0.69WO3 atomic structure has been refined (198 independent reflections) taking into account the anisotropy of thermal vibrations (Rw = 4.0%). The stoichiometric coefficient Na(0.69) is also refined. A structural distortion is revealed, which is characterized by the displacement of oxygen atoms (0, 0.2609(2), 0.2391(2)) from the ideal perovskite positions (0, 1/4, 1/4); this displacement doubles the ideal perovskite lattice period. The oxygen displacements can be described as rotations of oxygen octahedra by 3.58° around the [111] direction. The structure remains cubic because the octahedra rotations with respect to all three perovskite cubic axes are identical.

  14. Bronze rainbow hologram mirrors

    Science.gov (United States)

    Dawson, P.

    2006-02-01

    This project draws on holographic embossing techniques, ancient artistic conventions of bronze mirror design and modelling and casting processes to accomplish portraiture of reflection. Laser scanning, 3D computer graphics and holographic imaging are employed to enable a permanent 3D static holographic image to appear integrated with the real-time moving reflection of a viewer's face in a polished bronze disc. The disc and the figure which holds it (caryatid) are cast in bronze from a lost wax model, a technique which has been used for millennia to make personal mirrors. The Caryatid form of bronze mirror which went through many permutations in ancient Egyptian, Greece and Rome shows a plethora of expressive figure poses ranging from sleek nudes to highly embellished multifigure arrangements. The prototype of this series was made for Australian choreographer Graeme Murphy, Artistic Director of the Sydney Dance Company. Each subsequent mirror will be unique in figure and holographic imagery as arranged between artist and subject. Conceptually this project references both the modern experience of viewing mirrors retrieved from ancient tombs, which due to deterioration of the surface no longer reflect, and the functioning of Chinese Magic mirrors, which have the ability to project a predetermined image. Inspired by the metaphorical potential of these mirrors, which do not reflect the immediate reality of the viewer, this bronze hologram mirror series enables each viewer to reflect upon himself or herself observing simultaneously the holographic image and their own partially obliterated reflection.

  15. Phase transitions and electrical characterizations of (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics with 'unfilled' and 'filled' tetragonal tungsten-bronze (TTB) crystal structure

    KAUST Repository

    Yao, Yingbang

    2012-12-01

    Alkali-doped strontium barium niobate (K 0.5Na 0.5) 2x(Sr 0.6Ba 0.4) 5-xNb 10O 30 (KNSBN) ceramics has been prepared by a conventional solid-state reaction method. The alkali-dopant concentration x has been varied from 0.24 to 1.15 so that the crystal structure was transformed from \\'unfilled\\' to \\'filled\\' tetragonal tungsten-bronze (TTB) structure. Apart from the change in the structural properties, the effects of the alkali-dopants on the phase transition as well as ferroelectric, piezoelectric and pyroelectric properties have also been investigated. Phase transitions have been studied in the temperature range of -200°C to 350°C. The origins of these phase transitions are discussed. The addition of the alkali-dopants enhances the ferroelectric, piezoelectric and pyroelectric properties of the KNSBN ceramics. Alkali-doping also favors abnormal grain growth and thus results in a porous microstructure, which might contribute to the enhancement of the pyroelectric performance. © 2012 Elsevier Ltd.

  16. Bronze Age Acrobats

    DEFF Research Database (Denmark)

    Iversen, Rune

    2014-01-01

    immaterial, ritual and cosmological exchange that characterized the second and early firstmillennium BC.Beliefs and ritual practices went hand in hand with the adoption of a series of elite items and an aristocratic lifestyle, thereby creating a unique and fascinating European Bronze Age....

  17. Precipitation and ion floatation of molybdenum, tungsten, copper, and cobalt compounds by cetyltrimethylammonium bromide and sodium diethyldithiocarbamate

    International Nuclear Information System (INIS)

    Experimental data are presented on application of ion-flotation in purification of low-concentration (less than 10-3 M) acid solutions from molybdenum, tungsten, copper and cobalt ions. Two collectors, i.e. DEDC and CTMAB have been tested, their optimal consumption is determined. It is shown that CTMAB provides for selective purification from Mo and W ions and allows foam product with little water on flotation in a column to be obtained. But the achieved residual W and Mo concentration of 20 to 10 mg/l require deeper finishing purification in order to meet a sanitary permissible limiting concentration value employing other methods. DEDC provides for sufficient purification from nonferrous metal ions but does not possess selectivity with respect to some metals. The obtained results have shown the possibility to apply ion-flotation in concentration of metal ions in foam product in the process of waste water purification with further finishing purification up to a sanitary permissible limiting concentration value. 14 refs.; 3 figs.; 1 tab

  18. Ancient Chinese Bronzes: Teacher's Packet.

    Science.gov (United States)

    Smithsonian Institution, Washington, DC. Arthur M. Sackler Gallery.

    The focus of this teacher's packet is the bronze vessels made for the kings and great families of the early Chinese dynasties between 1700 B.C. and 200 A.D. The materials in the guide are intended for use by teachers and students visiting the exhibition, "The Arts of China," at the Arthur M. Sackler Gallery of the Smithsonian Institution in…

  19. Bronze Statuettes in Roman Graves

    Directory of Open Access Journals (Sweden)

    Margherita Bolla

    2014-02-01

    Full Text Available This research follows the investigations about the relationship between bronze statuettes and contexts in Roman times, particularly explored by Annemarie Kaufmann-Heinimann. The rarity of bronze figures (human, divine and animals in Roman tombs of Imperial age has been repeatedly emphasized. The aim of the paper is the collection, not exhaustive, of evidences in funerary contexts, to determine their meaning. From a methodological point of view, it was necessary to exclude figurines placed in graves but with other originary functions and several bronzes whose finding in tombs is unreliable. This preliminary survey has given about eighty all-round bronzes from burials, distributed in different areas, both in the Empire and marginal. Considering the huge amount of Roman burials known today, the overall evidence is scarce but allows some observations; it is evident the pre-eminence of Venus and Mercury, gods which had a funerary role. There is also an attempt to find the reasons of the rarity of metal statuettes in the tombs of roman period.

  20. Decorative layers on tin bronzes

    Directory of Open Access Journals (Sweden)

    Z. Konopka

    2010-10-01

    Full Text Available Decorative layers are decisive for aesthetic value of castings, therefore significant demands are raised towards such layers, e.g. pleasant durable colour, gloss, and smoothness. The work discusses the influence of the type of mechanical working applied to the surfaces of CuSn10 tin bronze castings on the quality and durability of a decorative coating. The scope of the work has included designing and manufacturing of cast samples of tin bronze, mechanical working of the surfaces in order to prepare them for applying coating layers,generating decorative layers as a result of chemical reactions, and the quality assessment and comparison of the obtained coating. Theassessment of thickness and continuity of the obtained decorative layers based on metallographic examinations has been presented.

  1. The Bronze Age Smith as Individual

    DEFF Research Database (Denmark)

    Nørgaard, Heide Wrobel

    During 1550-1100 BC magnificent decorated bronze objects appear in grave and hoard finds in Northwest Europe. While investigating similarities in the decorative elements of bronze objects belonging to the female gender, it is possible to find traces of the production process. These distinctive fe...

  2. New Research on Bronze Age Textile Production

    DEFF Research Database (Denmark)

    Andersson, Eva Birgitta; Mårtensson, Linda; Nosch, Marie-Louise Bech;

    2008-01-01

    presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed.......presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed....

  3. Population genomics of Bronze Age Eurasia.

    Science.gov (United States)

    Allentoft, Morten E; Sikora, Martin; Sjögren, Karl-Göran; Rasmussen, Simon; Rasmussen, Morten; Stenderup, Jesper; Damgaard, Peter B; Schroeder, Hannes; Ahlström, Torbjörn; Vinner, Lasse; Malaspinas, Anna-Sapfo; Margaryan, Ashot; Higham, Tom; Chivall, David; Lynnerup, Niels; Harvig, Lise; Baron, Justyna; Della Casa, Philippe; Dąbrowski, Paweł; Duffy, Paul R; Ebel, Alexander V; Epimakhov, Andrey; Frei, Karin; Furmanek, Mirosław; Gralak, Tomasz; Gromov, Andrey; Gronkiewicz, Stanisław; Grupe, Gisela; Hajdu, Tamás; Jarysz, Radosław; Khartanovich, Valeri; Khokhlov, Alexandr; Kiss, Viktória; Kolář, Jan; Kriiska, Aivar; Lasak, Irena; Longhi, Cristina; McGlynn, George; Merkevicius, Algimantas; Merkyte, Inga; Metspalu, Mait; Mkrtchyan, Ruzan; Moiseyev, Vyacheslav; Paja, László; Pálfi, György; Pokutta, Dalia; Pospieszny, Łukasz; Price, T Douglas; Saag, Lehti; Sablin, Mikhail; Shishlina, Natalia; Smrčka, Václav; Soenov, Vasilii I; Szeverényi, Vajk; Tóth, Gusztáv; Trifanova, Synaru V; Varul, Liivi; Vicze, Magdolna; Yepiskoposyan, Levon; Zhitenev, Vladislav; Orlando, Ludovic; Sicheritz-Pontén, Thomas; Brunak, Søren; Nielsen, Rasmus; Kristiansen, Kristian; Willerslev, Eske

    2015-06-11

    The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought. PMID:26062507

  4. The Bronze Age Smith as Individual

    OpenAIRE

    Nørgaard, Heide Wrobel

    2011-01-01

    During 1550-1100 BC magnificent decorated bronze objects appear in grave and hoard finds in Northwest Europe. While investigating similarities in the decorative elements of bronze objects belonging to the female gender, it is possible to find traces of the production process. These distinctive features can help to identify workshops and their sphere of influence. Sometimes these traces have the ability to give much more information than just indicate the crafting process of the object. Errors...

  5. Tungsten Alloy Outgassing Measurements

    CERN Document Server

    Rutherfoord, John P; Shaver, L

    1999-01-01

    Tungsten alloys have not seen extensive use in liquid argon calorimeters so far. Because the manufacturing process for tungsten is different from the more common metals used in liquid argon there is concern that tungsten could poison the argon thereby creating difficulties for precision calorimetry. In this paper we report measurements of outgassing from the tungsten alloy slugs proposed for use in the ATLAS FCal module and estimate limits on potential poisoning with reasonable assumptions. This estimate gives an upper limit poisoning rate of tungsten slugs.

  6. Research on the Orientation of Decoration on Bronzes from Yinxu

    Institute of Scientific and Technical Information of China (English)

    岳洪彬

    2003-01-01

    The study of surface decoration is one important aspect of research on Yinxu 殷墟 bronzes and has been a particular focus of investigations of bronzes from the Three Dynasties. Previous scholars have already made great strides in this line of research and they have provided not only an important precedent for making chronological distinctions among the late Shang bronzes.

  7. “Neutron metallography” of archaeological bronzes

    Science.gov (United States)

    Siano, S.; Bartoli, L.; Kockelmann, W.; Zoppi, M.; Miccio, M.

    2004-07-01

    Following a first demonstration on the potentials of time-of-flight neutron diffraction in the microstructural characterisation of archaeological bronzes, we present here the results of a further systematic study on the topic. The experiments were performed on standardised specimens and original archaeological bronze findings at the powder diffractometer ROTAX. The possibility to achieve various metallographic data concerning alloy composition, homogeneity, dendritic structure, metal and mineral phases, as well as the effects of hardening, annealing, and re-crystallisation processes was successfully demonstrated. Furthermore, we also report a texture analysis on a Roman coin, which provided a clear striking fingerprint thus demonstrating a powerful authentication method.

  8. Tungsten filament fire

    Science.gov (United States)

    Ruiz, Michael J.; Perkins, James

    2016-05-01

    We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent light bulb is being replaced by compact fluorescent and LED lamps.

  9. 75 FR 14257 - Pricing for Bronze Medals

    Science.gov (United States)

    2010-03-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY United States Mint Pricing for Bronze Medals AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing the price of the 1\\5/16\\- inch...

  10. Copper and bronze coating with molybdenite

    International Nuclear Information System (INIS)

    The conditions were studied for producing qualitative bronze self-lubricating composite electrochemical coatings (SCEC). The copper composite coatings have been produced from sulfate electrolyte used for copper plating. The bronze SCEC have been obtained from a bath of the composition: tin dichloride-35, copper chloride-40, pyrophosphoric potassium-490. The problem of the optimal planning of Cu-MoS2 composite coatings characteristics has been considered. The matrix of the experiments planning is given, as well as the test results and numerical solution of coefficients of regression equations. The hardness of the bronze SCEC is affected most of all by the concentration and acidity of the suspension, and least of all - by the bath temperature. The friction coefficient of the self-lubricating coatings coupled with brass depends to a greater extent on the temperature and concentration of the suspension. The highest decrease of the friction coefficient can be expected at the minimum value of the abovesaid technological factors. The transient electric conductivity of the couple undergoing friction in air depends mainly on the cathode current density and concentration of dispersion phase in the electrolyte used for bronze plating. With the increase in the suspension concentration (and, therefore, in the amount of MoS2 inclusions into the coatings) the antifriction properties of the SCEC enhance. The dispersion addition increases the transient electric conductivity of the contact, however this does not prevent SCEC from being used in electrocommutation devices

  11. Population genomics of Bronze Age Eurasia

    DEFF Research Database (Denmark)

    Allentoft, Morten E.; Sikora, Martin; Sjögren, Karl-Göran;

    2015-01-01

    The Bronze Age of Eurasia (around 3000-1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We inv...... a more recent onset of positive selection on lactose tolerance than previously thought....

  12. Textbook tests with tungsten

    CERN Multimedia

    Barbara Warmbein

    2010-01-01

    CERN's linear collider detector group joins forces with CALICE in building the world's first tungsten hadronic calorimeter.   Hadronic calorimeter prototype made of tungsten for the linear collider detector being equipped with CALICE scintillators. In a hall for test beam experiments at CERN, next to the CLOUD climate experiment and an irradiation facility, sits a detector prototype that is in many ways a first. It's the first ever hadronic sandwich calorimeter (HCal) prototype made of tungsten. It's the first prototype for a detector for the Compact Linear Collider Study CLIC, developed by the linear collider detector R&D group (LCD group) at CERN. And it's the first piece of hardware that results directly from the cooperation between CLIC and ILC detector study groups. Now its makers are keen to see first particle showers in their detector. The tungsten calorimeter has just moved from a workshop at CERN, where it was assembled from finely polished tungsten squares and triangles, into the ...

  13. Corrosion of high-density sintered tungsten alloys. Part 1

    International Nuclear Information System (INIS)

    The corrosion behaviour of four tungsten alloys has been evaluated through weight loss measurements after total immersion in both distilled water insight into the mechanism of corrosion was afforded by an examination of the and 5% sodium chloride solutions. Some insight the mechanism of corrosion was afforded by using the Scanning Electron Microscopy and through an analysis of the corrosion products. Pure tungsten and all the alloys studied underwent corrosion during the tests, and in each case the rare of corrosion in sodium chloride solution was markedly less than that in distilled water. A 95% W, 3.5% Ni, 1.5% Fe alloy was found to be the most corrosion resistant of the alloys under the experimental conditions. Examination of the data shows that for each of the tests, copper as an alloying element accelerates corrosion of tungsten alloys. 9 refs., 7 tabs., 12 figs

  14. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  15. 77 FR 14600 - Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse Bronze Medal...

    Science.gov (United States)

    2012-03-12

    ... United States Mint Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse.... SUMMARY: The United States Mint is announcing 2012 pricing for Kennedy Half-Dollar bags and rolls, bronze..., Associate Director for Sales and Marketing; United States Mint; 801 9th Street NW., Washington, DC 20220;...

  16. Gold and Silver Inlaid Bronze Sheep

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Gold and silver inlaying is a metal processing technique popular during the Spring and Autumn Period (770-476 B. C.) and the Warring States Period (475-221 B. C.). Patterns on the surface of the bronze figure are chiselled out and gold and silver threads (which can be as thin as hair) are inlaid. Finally the whole figure is filed and polished resulting in a splendid artistic work highlighting the different colours of the three different kinds of metal. The artifact shown here was unearthed from Ningxia'...

  17. Tungsten diffusion in olivine

    Science.gov (United States)

    Cherniak, D. J.; Van Orman, J. A.

    2014-03-01

    Diffusion of tungsten has been characterized in synthetic forsterite and natural olivine (Fo90) under dry conditions. The source of diffusant was a mixture of magnesium tungstate and olivine powders. Experiments were prepared by sealing the source material and polished olivine under vacuum in silica glass ampoules with solid buffers to buffer at NNO or IW. Prepared capsules were annealed in 1 atm furnaces for times ranging from 45 min to several weeks, at temperatures from 1050 to 1450 °C. Tungsten distributions in the olivine were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for W diffusion in forsterite: D=1.0×10-8exp(-365±28 kJ mol/RT) m s Diffusivities for the synthetic forsterite and natural Fe-bearing olivine are similar, and tungsten diffusion in olivine shows little dependence on crystallographic orientation or oxygen fugacity. The slow diffusivities measured for W in olivine indicate that Hf-W ages in olivine-metal systems will close to diffusive exchange at higher temperatures than other chronometers commonly used in cosmochronology, and that tungsten isotopic signatures will be less likely to be reset by subsequent thermal events.

  18. OPAL Silicon Tungsten Luminometer

    CERN Multimedia

    OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. The Silicon Tungsten Luminometer was part of OPAL's calorimeter which was used to measure the energy of particles. Most particles end their journey in calorimeters. These detectors measure the energy deposited when particles are slowed down and stopped.

  19. The determination of tungsten and iron in ferrotungsten alloys by x-ray-fluorescence spectrometry

    International Nuclear Information System (INIS)

    An accurate and precise method for the determination of tungsten and iron in ferrotungsten alloys is described. Samples are prepared for analysis by fusion with sodium peroxide and sodium hydroxide in a zirconium crucible. The melt is leached in water and acidified with hydrochloric acid. The tungstic acid thus produced is brought into solution by formation of a complex with tartaric acid. Matrix correction and calibration are achieved by means of the single-standard calibration method, use being made of a reference solution for tungsten prepared from sodium tungstate and a reference solution for iron prepared from iron wire

  20. Tungsten oxide nanowire synthesis from amorphous-like tungsten films.

    Science.gov (United States)

    Seelaboyina, Raghunandan

    2016-03-18

    A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis. PMID:26871521

  1. Atomically resolved images of lithium purple bronze

    Energy Technology Data Exchange (ETDEWEB)

    Klinke, Melanie; Bienert, Robert; Waelsch, Michael; Podlich, Tatjana; Matzdorf, Rene [Experimentalphysik II, Universitaet Kassel (Germany); Jin, Rongying [Department of Physics and Astronomy, Lousiana State University (United States)

    2012-07-01

    The lithium molybdenum purple bronze Li{sub 0.9}Mo{sub 6}O{sub 17} is a quasi 1D metal at room temperature showing Luttinger liquid physics. The highly anisotropic conductivity runs along the crystallographic b axis where Mo-O chains, formed by the shared edges of the MoO{sub 6} octahedra, provide the electrical transport. Li{sub 0.9}Mo{sub 6}O{sub 17} samples were investigated with low-temperature scanning tunneling microscopy and spectroscopy. By cleaving the samples at low temperatures (60 K) we obtained atomically resolved images of the surface. In these images the Mo-O chains are visible, which are covered by layers of MoO{sub 6} octahedra and MoO{sub 4} tetrahedra.

  2. Russian meteorite Bronze Age (rock record)

    CERN Document Server

    Vodolazhskaya, Larisa

    2013-01-01

    This paper presents the results of a study of petroglyphs found in the quartzite grotto near the Skelnovsky small village in the Northern Black Sea in the South of Russia. The aim of the study was the analysis and interpretation of the Early Bronze Age petroglyphs using archaeoastronomical methods. The article presents a comparative analysis of Skelnovsky grotto ancient images and contemporary eyewitness accounts of the Sikhote-Alin meteorite fall and meteorite shower. Some petroglyphs were interpreted by us using ethnographic and folklore material. In this study, the magnetic declination for the geographical coordinates Skelnovsky farm was calculated, and the projection of the whole picture Skelnovskih petroglyphs on the topographical map of the area was built. The proposed location of the meteorite fall was determined with this projection. It is confirmed by satellite pictures, on which are the distinguishable terrain features, typical for the meteorite fall, are visible including the possible impact crater...

  3. Stamps of New China Eastern Zhou Dynasty Bronzes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The State Postal Bureau’s latest set of special stamps for 2003 features Eastern Zhou Dynasty (770-256 B,C.) bronzes. This eight-stamp set is the third to feature this type of relic; a set issued in 1964 depicted bronzes from the Yin Dynasty (14th-11th century}, and one featuring Western Zhou Dynasty (11th century-771 B.C.) bronzes was released in 1982.The Eastern Zhou Dynasty followed the Western, and during this period, bronze vessel casting developed remarkably. Artifacts from this period include sacrificial vessels, musical instruments, utensils, weapons and tools.One of these pieces, a rectangular tray decorated with tortoise and fish patterns, dates back to the late Spring and Autumn Period

  4. Reversibility of the lithium-vanadium bronze structure when cycled

    International Nuclear Information System (INIS)

    The positive electrodes of the lithium secondary current sources, manufactured on the basis of the Li1+x V3O8 lithium-vanadium bronze, obtained through the alcoxotechnology, are studied. It is established, that in proportion to the lithium introduction the initial crystalline bronze renders amorphous, remaining a single-phase one. Increase in the x-lithifying rate leads practically to decrease in the α-parameters and increase in the b- and c-parameters of the bronze crystal lattice, whereby these changes are quite reversible by cycling. The obvious degradation of the electrode electrical parameters is not connected with irreversible structural changes and may be explained by formation of passive films on the surface of the particles of the lithium-vanadium bronze

  5. Helium bubble bursting in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Sefta, Faiza [University of California, Berkeley, California 94720 (United States); Juslin, Niklas [University of Tennessee, Knoxville, Tennessee 37996 (United States); Wirth, Brian D., E-mail: bdwirth@utk.edu [University of Tennessee, Oak Ridge National Laboratory, Knoxville, Tennessee 37996 (United States)

    2013-12-28

    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.

  6. Preparation of tungsten oxide

    Science.gov (United States)

    Bulian, Christopher J.; Dye, Robert C.; Son, Steven F.; Jorgensen, Betty S.; Perry, W. Lee

    2009-09-22

    Tungsten trioxide hydrate (WO.sub.3.H.sub.2O) was prepared from a precursor solution of ammonium paratungstate in concentrated aqueous hydrochloric acid. The precursor solution was rapidly added to water, resulting in the crash precipitation of a yellow white powder identified as WO.sub.3.H.sub.2O nanosized platelets by x-ray diffraction and scanning electron microscopy. Annealing of the powder at 200.degree. C. provided cubic phase WO.sub.3 nanopowder, and at 400.degree. C. provided WO.sub.3 nanopowder as a mixture of monoclinic and orthorhombic phases.

  7. 75 FR 57825 - Culturally Significant Objects Imported for Exhibition Determinations: “Ancient Chinese Bronzes...

    Science.gov (United States)

    2010-09-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition Determinations: ``Ancient Chinese Bronzes From the... objects to be included in the exhibition ``Ancient Chinese Bronzes from the Shouyang Studio: The...

  8. Electrochemical testing of laser treated bronze surface

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [Dept. of Mechanical Engineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261 (Saudi Arabia); Toor, Ihsan-ul-Haq; Malik, Jahanzaib; Patel, F. [Dept. of Mechanical Engineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261 (Saudi Arabia); Karatas, C. [Engineering Faculty, Hacettepe University, Ankara (Turkey)

    2013-06-25

    Highlights: ► Laser treated surface is free from asperities. ► Laser treated layer extends uniformly below the surface with a thickness in the order of 40 μm. ► Presence of Cu{sub 3}N nitrides is evident from X-ray diffractogram. ► Dendritic structure is formed below the surface due to relatively slower cooling rates as compared to that at the surface. ► The corrosion current density for the laser treated surface is much less than that of the as-received surface. -- Abstract: Electrochemical testing of laser treated bronze surface is carried out and corrosion resistance of the surface is assessed. Morphological and metallurgical changes in the laser treated layer are examined using scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction. The pit sites formed at the surface are analyzed using scanning electron microscope. It is found that laser treatment improves the corrosion resistance of the treated surface. Fine grains are formed in the surface region of the laser treated layer, which are attributed to the large cooling rates from the surface.

  9. Study of patina formation on bronze specimens

    International Nuclear Information System (INIS)

    In this study, bronze samples (94.059% Cu; 0.023% Zn; 0.077% Pb and 5.801% Sn, w/w) were exposed for 8 months to a marine atmosphere (splash zone) at Barra of Tijuca Beach, Rio de Janeiro. X-ray diffraction analysis (XRD) was used to identify the composition of the corrosion products formed on the samples. The electrochemical properties were analyzed using potential and electrochemical impedance measurements. These analyses and measurements were obtained from periodically removed samples, and compared to those exposed to laboratory tests (total and alternating immersion) in 10-2 mol L-1 NaCl solution. The corrosion potential results, allied to XRD analysis, showed that the chemical nature of the films obtained on the surface of the field test samples was very similar to that obtained in the alternating immersion test. The main products identified were cuprite and atacamite. However, the film formed during the total immersion (TI) test was primarily composed of cuprite with nantokite traces, which was not observed in either the field or in alternating tests. The electrochemical impedance measurements obtained in laboratory and field test samples showed the formation of films with a porous structure. The thermodynamic evaluation was also consistent with the corrosion products formed.

  10. Evaluation of Bio-field Treatment on Physical and Structural Properties of Bronze Powder

    OpenAIRE

    Mahendra Kumar Trivedi; Gopal Nayak; Rama Mohan Tallapragada

    2015-01-01

    Bronze, a copper-tin alloy, widely utilizing in manufacturing of gears, bearing, and packing technologies due to its versatile physical, mechanical, and chemical properties. The aim of the present work was to evaluate the effect of bio-field treatment on physical and structural properties of bronze powder. Bronze powder was divided into two samples, one served as control and the other sample was received bio-field treatment. Control and treated bronze samples were characterized using x-ray di...

  11. Evaluation of Biofield Treatment on Physical and Structural Properties of Bronze Powder

    OpenAIRE

    Trivedi, Mahendra; Nayak, Gopal

    2015-01-01

    Bronze, a copper-tin alloy, widely utilizing in manufacturing of gears, bearing, and packing technologies due to its versatile physical, mechanical, and chemical properties. The aim of the present work was to evaluate the effect of biofield treatment on physical and structural properties of bronze powder. Bronze powder was divided into two samples, one served as control and the other sample was received biofield treatment. Control and treated bronze samples were characterized using x-ray diff...

  12. Tungsten oxide in polymer electrolyte fuel cell electrodes-A thin-film model electrode study

    Energy Technology Data Exchange (ETDEWEB)

    Wickman, Bjoern, E-mail: bjorn.wickman@chalmers.s [Competence Centre for Catalysis, Department of Applied Physics, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Wesselmark, Maria; Lagergren, Carina; Lindbergh, Goeran [Applied Electrochemistry, School of Chemical Science and Engineering, KTH, SE-100 44 Stockholm (Sweden)

    2011-10-30

    Highlights: > Platinum and tungsten oxide thin-film electrocatalysts. > Single cell fuel cell evaluation. > Hydrogen-tungsten bronze formation. > CO oxidation on platinum on tungsten oxide. - Abstract: Thin films of WO{sub x} and Pt on WO{sub x} were evaporated onto the microporous layer of a gas diffusion layer (GDL) and served as model electrodes in the polymer electrolyte fuel cell (PEFC) as well as in liquid electrolyte measurements. In order to study the effects of introducing WO{sub x} in PEFC electrodes, precise amounts of WO{sub x} (films ranging from 0 to 40 nm) with or without a top layer of Pt (3 nm) were prepared. The structure of the thin-film model electrodes was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy prior to the electrochemical investigations. The electrodes were analyzed by cyclic voltammetry and the electrocatalytic activity for hydrogen oxidation reaction (HOR) and CO oxidation was examined. The impact of Nafion in the electrode structure was examined by comparing samples with and without Nafion solution sprayed onto the electrode. Fuel cell measurements showed an increased amount of hydrogen tungsten bronzes formed for increasing WO{sub x} thicknesses and that Pt affected the intercalation/deintercalation process, but not the total amount of bronzes. The oxidation of pre-adsorbed CO was shifted to lower potentials for WO{sub x} containing electrodes, suggesting that Pt-WO{sub x} is a more CO-tolerant catalyst than Pt. For the HOR, Pt on thicker films of WO{sub x} showed an increased limiting current, most likely originating from the increased electrochemically active surface area due to proton conductivity and hydrogen permeability in the WO{sub x} film. From measurements in liquid electrolyte it was seen that the system behaved very differently compared to the fuel cell measurements. This exemplifies the large differences between the liquid electrolyte and fuel cell systems. The thin-film model

  13. Deposition and Coating Properties on CVD Tungsten

    Institute of Scientific and Technical Information of China (English)

    DU Ji-hong; LI Zheng-xiang; LIU Gao-jian; ZHOU Hui-Huang; CHUN liang

    2004-01-01

    Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.

  14. Sodium Azide

    Science.gov (United States)

    ... Matters What's New A - Z Index Facts About Sodium Azide What sodium azide is Sodium azide is a rapidly acting, ... give people sufficient warning of the danger. Where sodium azide is found and how it is used ...

  15. Prompt gamma-ray analysis of archaeological bronze

    International Nuclear Information System (INIS)

    Prompt γ-ray analysis using the internal monostandard method was applied to voluminous archaeological bronze mirrors produced in ancient China. Sn/Cu content ratios were determined nondestructively by this method. Furthermore, Au/Cu, As/Cu, and Sb/Cu content ratios were determined by means of measuring decay γ-rays emitted from radioactive nuclides produced within samples via (n,γ) reactions. It is clear that the Sn/Cu content ratios in bronze mirrors produced in the Sung era is smaller than in ones produced in between the Han and the Tung era. (author)

  16. The Early Bronze Age Dwellings in the Southern Levant

    Directory of Open Access Journals (Sweden)

    Deborah Sebag

    2007-10-01

    Full Text Available The house is a strategic base for the study of any given civilization. By studying the habitations, it is possible to find indications of not only the way of life of its occupants, their social organization, their world view, their needs, their resources but also of the available technologies. In this study, we will give a chronological presentation of the various types of dwellings through the Early Bronze age, in the Southern Levant. It is during the Early Bronze Age (3 100-2 000 B.C., t...

  17. Discovery of the Tungsten Isotopes

    OpenAIRE

    A. Fritsch; Ginepro, J. Q.; Heim, M.; Schuh, A.; SHORE, A.; Thoennessen, M

    2009-01-01

    Thirty-five tungsten 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.

  18. Archaeological investigations of the Bronze Age village of Bagnara di Romagna (RA

    Directory of Open Access Journals (Sweden)

    Maurizio Cattani

    2014-12-01

    Full Text Available This paper summarizes the results of researches carried out in the area next to the modern village of Bagnara di Romagna (RA, where several evidences related to a Bronze Age settlement have been collected. Recently test trenches and surface collections allowed to retrieve bronze and ceramics dating from the Middle Bronze Age (phase BM2 to the Recent Bronze Age (phase BR2. The analysis of landscape and the palaeoenvironmental reconstruction complete the outline of the region of Imola, Faenza and Lugo during the Bronze Age where are well known the ancient settlements of Solarolo, via Ordiere, Monte Castellaccio end S. Giuliano di Toscanella.

  19. Method to manufacture tungsten carbide

    International Nuclear Information System (INIS)

    The patent deals with an improved method of manufacturing tungsten carbide. An oxide is preferably used as initial product whose particle size and effective surface approximately corresponds to that of the endproduct. The known methods for preparing the oxide are briefly given. Carbon monoxide is passed over the thus obtained oxide particles whereby the reaction mixture is heated to a temperature at which tungsten oxide and carbon monoxide react and tungsten carbide is formed, however, below that temperature at which the tungsten-containing materials are caked or sintered together. According to the method the reaction temperature is about below 9000C. The tungsten carbide produced has a particle size of under approximately 100 A and an active surface of about 20 m2/g. It has sofar not been possible with the usual methods to obtain such finely divided material with such a large surface. These particles may be converted back to the oxide by heating in air at low temperature without changing particle size and effective surface. One thus obtains a tungsten oxide with smaller particle size and larger effective surface than the initial product. (IHOE)

  20. Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nadja B.D. da [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, s/n, Pelotas, RS (Brazil); Pazinato, Julia C.O. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Sombrio, Guilherme; Pereira, Marcelo B.; Boudinov, Henri [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Gündel, André; Moreira, Eduardo C. [Universidade Federal do Pampa, Travessa 45, 1650 Bagé, RS (Brazil); Garcia, Irene T.S., E-mail: irene.garcia@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

    2015-03-02

    Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na{sub 2}HPO{sub 4} as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na{sub 2}HPO{sub 4} present similar photocatalytic activity.

  1. Origin of the mysterious Yin-Shang bronzes in China indicated by lead isotopes

    Science.gov (United States)

    Sun, Wei-dong; Zhang, Li-peng; Guo, Jia; Li, Cong-ying; Jiang, Yu-hang; Zartman, Robert E.; Zhang, Zhao-feng

    2016-01-01

    Fine Yin-Shang bronzes containing lead with puzzlingly highly radiogenic isotopic compositions appeared suddenly in the alluvial plain of the Yellow River around 1400 BC. The Tongkuangyu copper deposit in central China is known to have lead isotopic compositions even more radiogenic and scattered than those of the Yin-Shang bronzes. Most of the Yin-Shang bronzes are tin-copper alloys with high lead contents. The low lead and tin concentrations, together with the less radiogenic lead isotopes of bronzes in an ancient smelting site nearby, however, exclude Tongkuangyu as the sole supplier of the Yin-Shang bronzes. Interestingly, tin ingots/prills and bronzes found in Africa also have highly radiogenic lead isotopes, but it remains mysterious as to how such African bronzes may have been transported to China. Nevertheless, these African bronzes are the only bronzes outside China so far reported that have lead isotopes similar to those of the Yin-Shang bronzes. All these radiogenic lead isotopes plot along ~2.0–2.5 Ga isochron lines, implying that deposits around Archean cratons are the most likely candidates for the sources. African cratons along the Nile and even micro-cratons in the Sahara desert may have similar lead signatures. These places were probably accessible by ancient civilizations, and thus are the most favorable suppliers of the bronzes. PMID:26988425

  2. Origin of the mysterious Yin-Shang bronzes in China indicated by lead isotopes

    Science.gov (United States)

    Sun, Wei-Dong; Zhang, Li-Peng; Guo, Jia; Li, Cong-Ying; Jiang, Yu-Hang; Zartman, Robert E.; Zhang, Zhao-Feng

    2016-03-01

    Fine Yin-Shang bronzes containing lead with puzzlingly highly radiogenic isotopic compositions appeared suddenly in the alluvial plain of the Yellow River around 1400 BC. The Tongkuangyu copper deposit in central China is known to have lead isotopic compositions even more radiogenic and scattered than those of the Yin-Shang bronzes. Most of the Yin-Shang bronzes are tin-copper alloys with high lead contents. The low lead and tin concentrations, together with the less radiogenic lead isotopes of bronzes in an ancient smelting site nearby, however, exclude Tongkuangyu as the sole supplier of the Yin-Shang bronzes. Interestingly, tin ingots/prills and bronzes found in Africa also have highly radiogenic lead isotopes, but it remains mysterious as to how such African bronzes may have been transported to China. Nevertheless, these African bronzes are the only bronzes outside China so far reported that have lead isotopes similar to those of the Yin-Shang bronzes. All these radiogenic lead isotopes plot along ~2.0–2.5 Ga isochron lines, implying that deposits around Archean cratons are the most likely candidates for the sources. African cratons along the Nile and even micro-cratons in the Sahara desert may have similar lead signatures. These places were probably accessible by ancient civilizations, and thus are the most favorable suppliers of the bronzes.

  3. The Partitioning of Tungsten bwtween Aqueous Fluids and Silicate Melts

    Institute of Scientific and Technical Information of China (English)

    许永胜; 张本仁; 等

    1993-01-01

    An experimental study has been carried out to determine the partition coefficients of tungsten between aqueous fluids and granitic melts at 800℃ and 1.5kb with natural granite as the starting material,The effects of the solution on the partition coefficients of tungsten show a wequence of P>co32->B>H2O.The effects are limited(generally KD<0.3)and the tungsten shows a preferential trend toward the melt over the aqueous fiuid.The value of KD increases with increasing concentration of phosphorus;the KD increases first and then reduces with the concentration of CO32-;when temperature decreases,the KD between the solution of CO32- and the silicate melt increases,and that between the solution of B4O72- and the silicate melt decreases.The partition coefficients of phosphorus and sodium between fluids and silicate melts have been calculated from the concentrations of the elements in the melts.The KD value for phosphorus is 0.38 and that for sodium is 0.56.Evidence shows that the elements tend to become richer and richer in the melts.

  4. Reporting Casting Bronze Plaque Becomes Advisers Class Project

    Science.gov (United States)

    Ross, Charlie

    1977-01-01

    Describes an advisers' class project (at the University of Oklahoma) which consisted of reporting on the casting of a bronze plaque bearing the names of the first school newspaper, "The Students Gazette," and its editor, Samuel M. Fox, for presentation in Philadelphia to commemorate scholastic journalism's Bicentennial. (MB)

  5. Panetta Awarded Bronze Star for Afghanistan Intel Mission

    OpenAIRE

    Naval Postgraduate School Public Affairs Office

    2008-01-01

    Fellow officers in full dress uniform, family and friends ringed the room in rapt attention as Naval Reserve Lt. James Panetta was awarded the Bronze Star Medal by Naval Postgraduate School President Daniel Oliver in a special ceremony in the President's Conference Room, Dec. 9.

  6. Corrosion behavior of leaded-bronze alloys in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Zohdy, K.M., E-mail: khalzohdy@yahoo.com [Higher Technological Institute, 10" t" h of Ramadan City (Egypt); Sadawy, M.M. [Mining and Petroleum Engineering Department, Al-Azhar University, Nasr City, Cairo 11371 (Egypt); Ghanem, M. [Industrial Education, Suez University (Egypt)

    2014-10-15

    The corrosion behavior of leaded-bronze alloys (Cu–5Sn–5Zn–5Pb, Cu–8Sn–8Zn–8Pb and Cu–10Sn–10Zn–10Pb) in sea water was investigated using weight loss method, open-circuit potential measurements (OCP), polarization techniques and electrochemical impedance spectroscopy (EIS). The nature and morphology of the corrosion products were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion resistance decreases with decreasing copper content. The XRD indicated that the composition of patina depends on the concentration of Cu, Sn, Zn and Pb in each alloy. - Highlights: • The corrosion potential of leaded bronze shifts to more noble potential. • The corrosion resistance increases with increasing amount of copper content in leaded bronze alloys. • The patina formed on Cu–5Sn–5Zn–5Pb is more uniform and protective than other alloys. • The composition of patina formed on leaded bronze depends on the concentration of Cu, Sn, Zn and Pb in the alloy.

  7. Electrodeposited nanocrystalline bronze alloys as replacement for Ni

    NARCIS (Netherlands)

    Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

    2008-01-01

    Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization curv

  8. Chemical characterization of CVD tungsten

    International Nuclear Information System (INIS)

    Characterization of tungsten films that have been deposited under ''selective'' conditions is presented. SEM and TEM studies indicate good conformal coverage and minimum encroachment. Cross section TEM results may indicate that some ''damage'' occurs at hole corners. Auger and SIMS depth profiles reveal very clean films. SIMS however does reveal that fluorine is a contaminant. Tungsten films were deposited at about 30A/min at 3000C with a 30/1 H/sub 2//WF/sub 6/ flow ration at 0.3 Torr. These films were selective up to film thicknesses of about 2000A. Mass spectral analysis of 99.8% WF/sub 6/ indicated no oxyfluorides and only a trace of methyl fluorosilanes that may have been an artifact of the gas sampling technique via contamination with silicone grease or lubricant. The sheet resistance of films became constant at about 8μ Ω-cm for film thicknesses (measured by profilometer after tungsten etch) greater than 4000A and increased up to about 20μ Ω-cm for very thin films (less than 500A). Auger depth profiling indicated that a thin oxide layer at the tungsten silicon interface corresponded to films having good adhesion as determined by a scribed tape pull test; where as a film deposited on a freshly HF cleaned surface with high carbon level had poor adhesion. Auger analysis indicated clean tungsten films with no evidence of fluorine. However, SIMS analysis indicated measurable levels of fluorine throughout the tungsten film and fluorine may be a significant contaminant as at higher temperatures it was found to have migrated to all interface areas as shown in SIMS study of annealed and unannealed W Six. The importance of fluorine impurities has not been correlated with any electrical properties

  9. Tungsten:Balance between Demand and Supply

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>In 2011,the tungsten market remained basically consistent with macro economic trends. In the first half of 2011, under the backdrop of upward economic situation,tungsten export and domestic consumption grew significantly and tungsten enterprises achieved remarkable economic benefits. However, as European debt crisis deepened in the second half of 2011, the global economic growth slowed down and

  10. The tungsten metallome of Pyrococcus furiosus

    NARCIS (Netherlands)

    Sevcenco, A.M.; Pinkse, M.W.H.; Bol, E.; Krijger, G.C.; Wolterbeek, H.T.; Verhaert, P.; Hagedoorn, P.L.; Hagen, W.R.

    2009-01-01

    The tungsten metallome of the hyperthermophilic archaeon Pyrococcus furiosus has been investigated using electroanalytical metal analysis and native-native 2D-PAGE with the radioactive tungsten isotope W-187 (t(1/2) = 23.9 h). P. furiosus cells have an intracellular tungsten concentration of 29 mu M

  11. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  12. The study of bronze statuettes with the help of neutron-imaging techniques

    OpenAIRE

    Van Langh, R.; Lehmann, E; Hartmann, S.; Kaestner, A.; Scholten, F.

    2009-01-01

    Until recently fabrication techniques of Renaissance bronzes have been studied only with the naked eye, microscopically, videoscopically and with X-radiography. These techniques provide information on production techniques, yet much important detail remains unclear. As part of an interdisciplinary study of Renaissance bronzes undertaken by the Rijksmuseum Amsterdam, neutron-imaging techniques have been applied with the aim of obtaining a better understanding of bronze workmanship during the R...

  13. Characterization of bronzes by abrasive stripping voltammetry and thin layer chromatography

    OpenAIRE

    Komorsky-Lovrić, Šebojka; Horvat, Alka J.M.; Ivanković, Danijela

    2006-01-01

    Corrosion potentials of five samples of bronzes having different compositions and the stripping peak potentials of their main components were determined by abrasive stripping voltammetry. Using thin-layer chromatography in combination with electrochemical dissolution of bronzes in the two electrode sampler, the ions of tin, copper, lead and nickel were detected as the products of electro-oxidation of bronzes. It is shown that the dissolution of tin is preferential at low potential differences...

  14. Rewriting the Central European Early Bronze Age Chronology: Evidence from Large-Scale Radiocarbon Dating.

    Directory of Open Access Journals (Sweden)

    Philipp W Stockhammer

    Full Text Available The transition from the Neolithic to the Early Bronze Age in Central Europe has often been considered as a supra-regional uniform process, which led to the growing mastery of the new bronze technology. Since the 1920s, archaeologists have divided the Early Bronze Age into two chronological phases (Bronze A1 and A2, which were also seen as stages of technical progress. On the basis of the early radiocarbon dates from the cemetery of Singen, southern Germany, the beginning of the Early Bronze Age in Central Europe was originally dated around 2300/2200 BC and the transition to more complex casting techniques (i.e., Bronze A2 around 2000 BC. On the basis of 140 newly radiocarbon dated human remains from Final Neolithic, Early and Middle Bronze Age cemeteries south of Augsburg (Bavaria and a re-dating of ten graves from the cemetery of Singen, we propose a significantly different dating range, which forces us to re-think the traditional relative and absolute chronologies as well as the narrative of technical development. We are now able to date the beginning of the Early Bronze Age to around 2150 BC and its end to around 1700 BC. Moreover, there is no transition between Bronze (Bz A1 and Bronze (Bz A2, but a complete overlap between the type objects of the two phases from 1900-1700 BC. We thus present a revised chronology of the assumed diagnostic type objects of the Early Bronze Age and recommend a radiocarbon-based view on the development of the material culture. Finally, we propose that the traditional phases Bz A1 and Bz A2 do not represent a chronological sequence, but regionally different social phenomena connected to the willingness of local actors to appropriate the new bronze technology.

  15. Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

    CERN Document Server

    Siano, S; Celli, M; Pini, R; Salimbeni, R; Zoppi, M; Kockelmann, W A; Iozzo, M; Miccio, M; Moze, O

    2002-01-01

    In this paper, we report the first investigation on the potentials of neutron diffraction to characterize archaeological bronze artifacts. The preliminary feasibility of phase and structural analysis was demonstrated on standardised specimens with a typical bronze alloy composition. These were realised through different hardening and annealing cycles, simulating possible ancient working techniques. The Bragg peak widths that resulted were strictly dependent on the working treatment, thus providing an important analytical element to investigate ancient making techniques. The diagnostic criteria developed on the standardised specimens were then applied to study two Etruscan museum pieces. Quantitative multiphase analysis by Rietveld refinement of the diffraction patterns was successfully demonstrated. Furthermore, the analysis of patterns associated with different artifact elements also yielded evidence for some peculiar perspective of the neutron diffraction diagnostics in archeometric applications. (orig.)

  16. Friction stir processing / welding of NiAl bronzes

    OpenAIRE

    McNelley, Terry; Menon, Sarath

    2016-01-01

    Research Project Friction stir processing (FSP) of as-cast NiAl bronzes converts the as-cast microstructure to a wrought condition in the volume of materials subjected to the process. This results in improved properties in the absence of component shape change. With the development of portable systems, friction stir processing may enable in situ repair of defective components such as propellers and thus avoid expensive procedures such as dry docking for such repairs.

  17. NUMERICAL MODELING OF HARDENING OF UNINTERRUPTEDLY-CASTED BRONZE CASTING

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2009-01-01

    Full Text Available The three-dimensional numerical model for calculation of thermal fields during solidification of continuously casted bronze casting is developed. Coefficients of heat transfer on borders of calculation areas on the basis of the solution of inverse heat transfer conduction problem are determined. The analysis of thermal fields, depending on loop variables of drawing and the sizes of not cooled zone of crystallizer is curried out.

  18. Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

    OpenAIRE

    Napachat Tareelap; Kaysinee Sriraksasin; Nakorn Srisukhumbowornchai; Swieng Thuanboon; Choochat Nitipanyawong

    2014-01-01

    Due to the failure of manganese aluminium bronze (MAB) propeller caused by dealloying corrosion as described in Part I [1], this work aims to study the prevention of dealloying corrosion using aluminium and zinc sacrificial anodes. The results indicated that both of the sacrificial anodes could prevent the propeller from dealloying. Moreover, the dealloying in seawater was less than that found in brackish water. It was possible that hydroxide ions, from cathodic reaction, reacted with calcium...

  19. The Development of Iron Technology in the Mediterranean Bronze Age

    OpenAIRE

    Leek, Rodney Thomas

    2014-01-01

    In the eastern Mediterranean region in the Bronze Age there were a number of elite controlled, complex societies that through cultural activities and trade and international agreements, participated in a regional exchange economy. In the transition to Iron Age there was a confusing period with wars, migrations and the collapse of most of the elite societies,. At this time, iron technology had already spread to some parts of the region. When the regional economy collapsed in c. 1200 BC it crea...

  20. Tungsten biochemistry of Pyrococcus furiosus

    NARCIS (Netherlands)

    Bevers, L.E.

    2008-01-01

    Tungsten is the heaviest element that exhibits biological activity (atomic number 74), when it is present in an enzyme. It is taken up by cells in the form of tungstate, and it is subsequently processed into an organic cofactor referred to as tungstopterin, which is found as active center in several

  1. Tantalum and vanadium substitution in hexagonal K{sub 0.3}WO{sub 3} bronze. Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md. Shahidur; Murshed, M. Mangir; Gesing, Thorsten M. [Bremen Univ. (Germany). Chemische Kristallographie fester Stoffe; Baabe, Dirk [Technische Univ. Braunschweig (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-02-01

    Polycrystalline samples of tantalum and vanadium single and double substituted hexagonal potassium tungsten bronzes (K-HTB's) with nominal compositions of K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}Ta{sup 5+}{sub y})O{sub 3} (0 ≤ y ≤ 0.3), K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}V{sup 5+}{sub y})O{sub 3} (0 ≤ y ≤ 0.18) and K{sub 0.3}(W{sup 6+}{sub 0.7}W{sup 5+}{sub 0.3-y}Ta{sup 5+}{sub y/2}V{sup 5+}{sub y/2})O{sub 3} (0 ≤ y ≤ 0.3) were synthesized by solid state reactions in quartz tubes at 10{sup -7} MPa and 1073 K. The applied synthesis condition allowed K{sub 0.3}WO{sub 3} to crystallize in space group P6{sub 3}22, confirmed by X-ray powder diffraction and Raman spectroscopic analyses. In this K-HTB composition, W{sup 5+} could fully be replaced by Ta{sup 5+}, whereas V{sup 5+} could only be substituted up to y=0.16. The degree of W{sup 5+} substitution was explained in terms of second-order Jahn-Teller (SOJT) distortion of the d{sup 0} cations W{sup 6+}, Ta{sup 5+} and V{sup 5+}. The applied distortion index also demonstrates why a complete substitution of W{sup 5+} in K{sub 0.3}(W{sup 6+}W{sup 5+})O{sub 3} was allowed by a concomitant sharing of Ta{sup 5+} and V{sup 5+}, which are statistically distributed on the W{sup 5+}/W{sup 6+} sites. As W{sup 5+}(d{sup 1}) is not SOJT susceptible, it is also shown that the concentration of W{sup 5+} in tungsten bronzes plays an important role in the local WO{sub 6} octahedral symmetry as well as in its coordination.

  2. Tamil Chola Bronzes and Swamimalai Legacy: Metal Sources and Archaeotechnology

    Science.gov (United States)

    Srinivasan, Sharada

    2016-05-01

    This review explores the great copper alloy image casting traditions of southern India from archaeometallurgical and ethnometallurgical perspectives. The usefulness of lead isotope ratio and compositional analysis in the finger-printing and art historical study of more than 130 early historic, Pallava, Chola, later Chola, and Vijayanagara sculptures (fifth-eighteenth centuries) is highlighted, including Nataraja, Buddha, Parvati, and Rama images made of copper, leaded bronze, brass, and gilt copper. Image casting traditions at Swamimalai in Tamil Nadu are compared with artistic treatises and with the technical examination of medieval bronzes, throwing light on continuities and changes in foundry practices. Western Indian sources could be pinpointed for a couple of medieval images from lead isotope analysis. Slag and archaeometallurgical investigations suggest the exploitation of some copper and lead-silver sources in the Andhra and Karnataka regions in the early historic Satavahana period and point to probable copper sources for the medieval images in Karnataka, Tamil Nadu, and Andhra Pradesh. The general lower iron content in southern Indian bronzes perhaps renders the proximal copper-magnetite reserves of Seruvila in Sri Lanka as a less likely source. Given the lack of lead deposits in Sri Lanka, however, the match of the lead isotope signatures of a well-known Ceylonese Buddhist Tara in British Museum with a Buddha image from Nagapattinam in Tamil Nadu may underscore ties between the island nation and the southern Indian Tamil regions.

  3. Matisse to Picasso: a compositional study of modern bronze sculptures.

    Science.gov (United States)

    Young, Marcus L; Schnepp, Suzanne; Casadio, Francesca; Lins, Andrew; Meighan, Melissa; Lambert, Joseph B; Dunand, David C

    2009-09-01

    Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to determine the bulk metal elemental composition of 62 modern bronze sculptures cast in Paris in the first half of the twentieth century from the collections of The Art Institute of Chicago and the Philadelphia Museum of Art. As a result, a comprehensive survey of the alloy composition of the sculptures of many prominent European artists of the early twentieth century is presented here for the first time. The sculptures in this study consist of predominantly copper with two main alloying elements (zinc and tin). By plotting the concentrations of these two elements (zinc and tin) against each other for all the sculptures studied, three clusters of data become apparent: (A) high-zinc brass; (B) low-zinc brass; (C) tin bronze. These clusters correlate to specific foundries, which used specific casting methods (sand or lost wax) that were influenced by individual preferences and technical skills of the foundry masters. For instance, the high-zinc brass alloys (with the highest levels of tin and zinc and the lowest melting temperature) correspond to most of the Picasso sculptures, correlate with the Valsuani foundry, and are associated with the most recent sculptures (post-WWII) and with the lost-wax casting method. By expanding the ICP-OES database of objects studied, these material correlations may become useful for identifying, dating, or possibly even authenticating other bronzes that do not bear foundry marks. Figure. PMID:19629458

  4. Tamil Chola Bronzes and Swamimalai Legacy: Metal Sources and Archaeotechnology

    Science.gov (United States)

    Srinivasan, Sharada

    2016-08-01

    This review explores the great copper alloy image casting traditions of southern India from archaeometallurgical and ethnometallurgical perspectives. The usefulness of lead isotope ratio and compositional analysis in the finger-printing and art historical study of more than 130 early historic, Pallava, Chola, later Chola, and Vijayanagara sculptures (fifth-eighteenth centuries) is highlighted, including Nataraja, Buddha, Parvati, and Rama images made of copper, leaded bronze, brass, and gilt copper. Image casting traditions at Swamimalai in Tamil Nadu are compared with artistic treatises and with the technical examination of medieval bronzes, throwing light on continuities and changes in foundry practices. Western Indian sources could be pinpointed for a couple of medieval images from lead isotope analysis. Slag and archaeometallurgical investigations suggest the exploitation of some copper and lead-silver sources in the Andhra and Karnataka regions in the early historic Satavahana period and point to probable copper sources for the medieval images in Karnataka, Tamil Nadu, and Andhra Pradesh. The general lower iron content in southern Indian bronzes perhaps renders the proximal copper-magnetite reserves of Seruvila in Sri Lanka as a less likely source. Given the lack of lead deposits in Sri Lanka, however, the match of the lead isotope signatures of a well-known Ceylonese Buddhist Tara in British Museum with a Buddha image from Nagapattinam in Tamil Nadu may underscore ties between the island nation and the southern Indian Tamil regions.

  5. Chemical and Electrochemical Characterization of Artificial Sulphate Patina on Bronze

    Institute of Scientific and Technical Information of China (English)

    MAO Yangwu; NIE Dunwei; MOMBELLO Domenico

    2014-01-01

    Copper patinas are generally regarded as aesthetically pleasing and are supposed to protect copper against further corrosion. The preparation of artificial sulphate patina on bronzes has been realized by immersing the bronze into CuSO4 solution. The effect of immersion time on the formation of the patina has been investigated. The sulphate patina obtained with immersion time of 500 h in CuSO4 solution consists of flat area and crystals. The flat area in the patina is mainly made of cuprite, whereas the crystals are mainly composed of brochantite. The electrochemical measurement of sulphate patina in simulated acid rain with pH 3.1 shows that the protective effectiveness of patina decreases with time and the dissolution of patina is the key factor leading to the degradation of patina. The investigation of the formation mechanism of sulphate patina shows that the cuprite layer forms on the surface of bronze in the initial patination. Then, crystal brochantite grows on the surface of cuprite by the oxidation of cuprite and the incorporation of CuSO4 solution.

  6. HANDICRAFT IN LATE BRONZE-EARLY IRON AGE IN NAKHCHIVAN

    Directory of Open Access Journals (Sweden)

    Toğrul HALİLOV

    2012-04-01

    Full Text Available The article handicraft have been learnt in the Nakhchivan late bronze-early iron age. It was defined that pottery wasone of the ancient craftsmanship areas in Nakhichivan. At that time Nakhichivan, as well as the other regions of Azerbaijan, was an important centre of craftsmanship. The pottery products differed from one another in their size, shape, ornaments on them, the material the were made of and the technology. The pottery products made by Nakhichivan potters were divided into two groups-welfare and kitchen ceramics. Their similar monuments in the South Caucasus and the Middle East in the same period, the archaeological materials found in the Urmia basin and Eastern Anatolia. As a result of comparative investigation it is defined that oldest labour tools producted from bone and stone in Nakchivan. New type of labour tools are producted connecting to treatmen of metal in following period. Stone and bone tools are used little in iron and bronz period. It is defined that daggers, arrow and spear heads, jewelry founded in archaeological monument belong to epoch late bronze-early iron age in the Nakhchivan have got peculiarity of culture of Khojalı-Gadabay in Azerbaijan. Some of daggers belong to culture Near East.

  7. Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps

    Directory of Open Access Journals (Sweden)

    Pee J.-H.

    2015-06-01

    Full Text Available Typical oxidation process of tungsten scraps was modified by the rotary kiln with oxygen burner to increase the oxidation rate of tungsten scraps. Also to accelerate the solubility of solid oxidized products, the hydrothermal reflux method was adapted. By heating tungsten scraps in rotary kiln with oxygen burner at around 900° for 2hrs, the scraps was oxidized completely. Then oxidized products (WO3 and CoWO4 was fully dissolved in the solution of NaOH by hydrothermal reflux method at 150° for 2hrs. The dissolution rate of oxidized products was increased with increasing the reaction temperature and concentration of NaOH. And then CaWO4 and H2WO4 could be generated from the aqueous sodium tungstate solution. Ammonium paratungstate (APT also could be produced from tungstic acid using by aqueous ammonium solution. The morphologies (cubic and plate types of APT was controlled by the stirring process of purified solution of ammonium paratungstate.

  8. Tungsten oxide nanowires grown on amorphous-like tungsten films.

    Science.gov (United States)

    Dellasega, D; Pietralunga, S M; Pezzoli, A; Russo, V; Nasi, L; Conti, C; Vahid, M J; Tagliaferri, A; Passoni, M

    2015-09-11

    Tungsten oxide nanowires have been synthesized by vacuum annealing in the range 500-710 °C from amorphous-like tungsten films, deposited on a Si(100) substrate by pulsed laser deposition (PLD) in the presence of a He background pressure. The oxygen required for the nanowires formation is already adsorbed in the W matrix before annealing, its amount depending on deposition parameters. Nanowire crystalline phase and stoichiometry depend on annealing temperature, ranging from W18O49-Magneli phase to monoclinic WO3. Sufficiently long annealing induces the formation of micrometer-long nanowires, up to 3.6 μm with an aspect ratio up to 90. Oxide nanowire growth appears to be triggered by the crystallization of the underlying amorphous W film, promoting their synthesis at low temperatures. PMID:26292084

  9. Synthesis of nanosized tungsten powder

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Nanosized tungsten powder was synthesized by means of different methods and under different conditions with nanosized WO3 powder. The powder and the intermediate products were characterized using XRD, SEM, TEM, BET (Brunauer Emmett Teller Procedure) and SAXS (X-ray diffracto-spectrometer/Kratky small angle scattering goniometer). The results show that nanosized WO3 can be completely reduced to WO2 at 600℃ after 40 min, and WO2 can be reduced to W at 700℃ after 90 min, moreover, the mean size of W particles is less than 40 nm. Furthermore, the process of WO3→WO2→W excelled that of WO3→W in getting stable nanosized tungsten powder with less grain size.

  10. Laser cleaning of tungsten ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Aniruddha, E-mail: nontee65@rediffmail.com [Advanced Fuel Fabrication Facility, Bhabha Atomic Research Centre, Tarapur, Maharashtra, 401504 (India); Sonar, V.R.; Das, D.K.; Bhatt, R.B.; Behere, P.G.; Afzal, Mohd.; Kumar, Arun [Advanced Fuel Fabrication Facility, Bhabha Atomic Research Centre, Tarapur, Maharashtra, 401504 (India); Nilaya, J.P.; Biswas, D.J. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, 400085 (India)

    2014-07-01

    Removal of a thin oxide layer from a tungsten ribbon was achieved using the fundamental, second and third harmonic radiation from a Q- switched Nd-YAG laser. It was found that beyond the threshold, oxide removal was achieved at all wavelengths for a wide range of fluence values. The removal mechanism of the oxide layer was found to be critically dependent on both wavelength and fluence of the incident radiation and has been identified as ejection or sublimation. The un-cleaned and cleaned surfaces were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of Neodymium atoms.

  11. The moessbauer spectroscopy study of an ancient bronze mirror without sampling

    International Nuclear Information System (INIS)

    The Moessbauer spectra of 119Sn for a bronze mirror of the Han Dynasty are described. A method of measuring Moessbauer spectrum without sampling is established. For the sake of contrast, both the spectra of transmission and of γ-ray scattering were measured. The results show that on the surface of the bronze mirror tin is in the state of Sn4+ oxide

  12. Abrasive wear of BA1055 bronze with additives of Si, Cr, Mo and/or W

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2008-10-01

    Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, aboutgood sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. The additions Mo and/or W were not applied so far. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the surface distribution of the concentration of elements in the microstructure of the studied bronze on X-ray microanalyzer were conducted. It results from conducted investigations, that in the aluminium bronze BA1055 after makes additions Si, Cr, Mo and/or W the phases of the type κFe, κNi crystallize, probably as complex silicides. Elements such as: Fe and Si dissolve first of all in phases κ, in smaller stage in the matrix of the bronze; Mn, Ni and W they dissolve in matrix and phases κ. It dissolves Cr and Mo in the larger stage in phases κ than in the matrix. The sizes of the abrasive wear were compared in the state cast multicomponentnew casting Cu-Al-Fe-Ni bronzes with the additives Cr, Mo or W with the wear of the bronze CuAl10Fe5Ni5Si. The investigations of thewear were conducted on the standard device. It results from conducted investigations, that make additions to bronze BA1055 of the additives of Si, Cr, Mo, and/or W it influences the rise of the hardness (HB of the bronze in the cast state, in the result of the enlarged quantity separates of hard phases κ, and in the consequence the decrease of the abrasive wear. The addition of molybdenum made possible obtainment of the microhardness of the phase α and γ 2 on the comparable level. From the microstructure of the bronze CuAl10Fe5Ni5MoSi is characterizes the smallest abrasive wear among

  13. Sodium Oxybate

    Science.gov (United States)

    Sodium oxybate is used to prevent attacks of cataplexy (episodes of muscle weakness that begin suddenly and ... urge to sleep during daily activities, and cataplexy). Sodium oxybate is in a class of medications called ...

  14. Sodium Test

    Science.gov (United States)

    ... be limited. Home Visit Global Sites Search Help? Sodium Share this page: Was this page helpful? Also known as: Na Formal name: Sodium Related tests: Chloride , Bicarbonate , Potassium , Electrolytes , Osmolality , Basic ...

  15. Sodium Phosphate

    Science.gov (United States)

    Sodium phosphate is used in adults 18 years of age or older to empty the colon (large intestine, bowel) ... view of the walls of the colon. Sodium phosphate is in a class of medications called saline ...

  16. Determining Foundry Area of Bronze Vessel Using REE in Clay Mould Residues

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The composition of casting clay core might provide clue to the foundry area of the bronze vessels. REE analysis of the residual clay mould was conducted by inductively coupled plasma atomic emission spectrometer (ICP-AES). Results reveal that characteristic of REE of clay mould from different region is dissimilar. It is feasible to restrict the possible foundry area of the bronze vessels on the basis of analysis of REE of clay mould residues on the bronzes. Meanwhile, this paper attempts to determine the foundry area of the bronze vessels unearthed at Jiuliandun tombs of Chu State, dated back to Warring States Period, in Zaoyang City, Hubei Province, and at Zuozhong cemetery, Spring and Autumn Period, in Jingmen City, Hubei Province. REE of clay core provides information on the foundry area of bronze vessels.

  17. Metallurgical and Chemical Characterization of Bronze Remains Found at the Houhe Site in Shanxi Province, China

    Science.gov (United States)

    Mu, D.; Nan, P. H.; Wang, J. Y.; Song, G. D.; Luo, W. G.

    2015-07-01

    This study attempts to determine the metallurgical and chemical characteristics of Chinese bronze artifacts from the early Iron Age by taking the bronze artifacts from the Houhe site as an example. The bronze artifacts included vessels, buckles, mirrors, and bells. Elemental compositions of 10 Chinese bronze artifacts from the Houhe site were determined by an x-ray fluorescence system. Microstructures were observed by a polarizing microscope. Most of the artifacts were cast and lacked external evidence of secondary processing. The copper content of the vessels is higher than the other samples, and the copper content of buckles is the lowest. High tin content is a distinctive characteristic of the mirrors. Through comparisons, bells show a decline in the content of copper from the Western Zhou dynasty to the early Han dynasty, and the content of lead increased over time. Combined with historical studies, the findings show that there may have been industrial standards for bronze production during the Han dynasty.

  18. Preliminary result on the analysis of Late Bronze Age metals

    International Nuclear Information System (INIS)

    Complete text of publication follows. The main event of the complex cultural changes during the transition from Middle to Late Bronze Age was the appearance of Tumulus culture in the Danube-Tisza region. In this period people rose mounds (tumuli) above their graves made from stone and soil. According to our present knowledge we believe that the ethnically inhomogeneous Tumulus culture was made homogenous by commerce (especially bronze commerce). Depots were typical of the final period of Middle Bronze Age called Koszider-phase. During the tumulus period the practice of hiding depots came to its end, bronze objects were put into graves. Therefore, it would be important to analyze the relation between the Koszider and Tumulus metallurgy. The main question to be answered is the following: were the trade connections and exchange of goods discontinued during the time of cultural changes? Examination of archaeological finds is carried out usually by typological methods which provide information on the attire fashion and funeral rite of cultures. The inherent capability of analytical techniques makes it possible to draw conclusions on the provenance of metals, thus facilitating to establish the contemporary trade routes. The metal finds from the southern part of the Great Hungarian Plain has not been investigated yet, though it would be important from the point of view of Tumulus culture. The main question is whether there is any noticeable change between the metallurgical craftsmanship of the consecutive eras. Therefore, it is important to determine the composition of the used raw materials, their sources, as well as the applied manufacturing technologies. For the characterization of archaeological bronze finds both conventional X-ray fluorescence (XRF) method and micro proton induced X-ray fluorescence (micro-PIXE) techniques are applied. The first one serves for the determination of the bulk composition of samples while the second one for the characterization of

  19. Trapping and release of helium in tungsten

    OpenAIRE

    Lhuillier, Pierre-Emile; Belhabib, Taieb; Desgardin, Pierre; Courtois, Blandine; Sauvage, Thierry; Barthe, Marie-France; Thomann, Anne-Lise; Brault, Pascal; Tessier, Yves

    2011-01-01

    The behavior of tungsten under irradiation and helium implantation is a major stake of the materialrelated issues of fusion reactors. In this perspective the fate of helium in tungsten was studied by mean of several characterization techniques. The aim of this study is to highlight the trapping mechanisms of helium in tungsten and their correlation with implantation-induced defects. Helium was implanted into tungsten at two different energies, 0.32 and 60 keV. The helium was studied as a func...

  20. Fine grain tungsten produced with nanoscale powder

    Institute of Scientific and Technical Information of China (English)

    Tao Lin; Fang Zhao; Liying Zhang; Chengyi Wu; Zhimeng Guo

    2005-01-01

    Nanoscale tungsten powder was prepared by reducing nanoscale tungsten trioxide in hydrogen to WO2.90 and further to W powder. After compacted with a rubber die, the nanoscale tungsten powder was sintered in a high-temperature dilatometer to investigate its shrinkage process. The results show that the compact of the nanoscale tungsten powder starts to shrink at 1050℃ and ends at 1500℃. The shrinkage rate reaches the maximum value at 1210℃. The relative density of sintered samples is 96.4%, and its grain size is about 5.8 μm.

  1. Investigation of laser cleaning on bronze cultural relics

    Science.gov (United States)

    Ling, Xiulan; Wang, Gao; Zhang, Chen

    2016-05-01

    The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm-2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens.

  2. Diffusion bonding of titanium alloy to tin-bronze

    Institute of Scientific and Technical Information of China (English)

    李卓然; 冯吉才; 刘会杰

    2002-01-01

    The vacuum diffusion bonding of titanium alloy to tin-bronze has been studied and the feasibility and appropriate processing parameters have been investigated. The maximum tensile strength of the joints is bonded joint has been observed by SEM, X-ray and EPMA, and the main factors affecting diffusion bonding have been analyzed. The intermetallic compounds Ti2Cu and TiCu were formed near the interface. The width and quantity of the intermetallic compound increases with the increase of the bonding time. The formation of the intermetallic compounds results in embrittlement of the joint and the poor joint properties.

  3. Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

    Directory of Open Access Journals (Sweden)

    Napachat Tareelap

    2014-03-01

    Full Text Available Due to the failure of manganese aluminium bronze (MAB propeller caused by dealloying corrosion as described in Part I [1], this work aims to study the prevention of dealloying corrosion using aluminium and zinc sacrificial anodes. The results indicated that both of the sacrificial anodes could prevent the propeller from dealloying. Moreover, the dealloying in seawater was less than that found in brackish water. It was possible that hydroxide ions, from cathodic reaction, reacted with calcium in seawater to form calcium carbonate film protecting the propeller from corrosion.

  4. Environmental roots of the late bronze age crisis.

    Science.gov (United States)

    Kaniewski, David; Van Campo, Elise; Guiot, Joël; Le Burel, Sabine; Otto, Thierry; Baeteman, Cecile

    2013-01-01

    The Late Bronze Age world of the Eastern Mediterranean, a rich linkage of Aegean, Egyptian, Syro-Palestinian, and Hittite civilizations, collapsed famously 3200 years ago and has remained one of the mysteries of the ancient world since the event's retrieval began in the late 19(th) century AD/CE. Iconic Egyptian bas-reliefs and graphic hieroglyphic and cuneiform texts portray the proximate cause of the collapse as the invasions of the "Peoples-of-the-Sea" at the Nile Delta, the Turkish coast, and down into the heartlands of Syria and Palestine where armies clashed, famine-ravaged cities abandoned, and countrysides depopulated. Here we report palaeoclimate data from Cyprus for the Late Bronze Age crisis, alongside a radiocarbon-based chronology integrating both archaeological and palaeoclimate proxies, which reveal the effects of abrupt climate change-driven famine and causal linkage with the Sea People invasions in Cyprus and Syria. The statistical analysis of proximate and ultimate features of the sequential collapse reveals the relationships of climate-driven famine, sea-borne-invasion, region-wide warfare, and politico-economic collapse, in whose wake new societies and new ideologies were created. PMID:23967146

  5. Environmental roots of the late bronze age crisis.

    Directory of Open Access Journals (Sweden)

    David Kaniewski

    Full Text Available The Late Bronze Age world of the Eastern Mediterranean, a rich linkage of Aegean, Egyptian, Syro-Palestinian, and Hittite civilizations, collapsed famously 3200 years ago and has remained one of the mysteries of the ancient world since the event's retrieval began in the late 19(th century AD/CE. Iconic Egyptian bas-reliefs and graphic hieroglyphic and cuneiform texts portray the proximate cause of the collapse as the invasions of the "Peoples-of-the-Sea" at the Nile Delta, the Turkish coast, and down into the heartlands of Syria and Palestine where armies clashed, famine-ravaged cities abandoned, and countrysides depopulated. Here we report palaeoclimate data from Cyprus for the Late Bronze Age crisis, alongside a radiocarbon-based chronology integrating both archaeological and palaeoclimate proxies, which reveal the effects of abrupt climate change-driven famine and causal linkage with the Sea People invasions in Cyprus and Syria. The statistical analysis of proximate and ultimate features of the sequential collapse reveals the relationships of climate-driven famine, sea-borne-invasion, region-wide warfare, and politico-economic collapse, in whose wake new societies and new ideologies were created.

  6. Corrosion characteristics of copper and leaded bronze in palm biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Haseeb, A.S.M.A.; Masjuki, H.H.; Ann, L.J.; Fazal, M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2010-03-15

    Biodiesel has become more attractive as alternative fuel for automobiles because of its environmental benefits and the fact that it is made from renewable sources. However, corrosion of metals in biodiesel is one of the concerns related to biodiesel compatibility issues. This study aims to characterize the corrosion behavior of commercial pure copper and leaded bronze commonly encountered in the automotive fuel system in diesel engine. Static immersion tests in B0, B50 and B100 fuels were carried out at room temperature for 2640 h. Similar immersion tests in B0, B100 and B100 (oxidized) fuels were also conducted at 60 C for 840 h. At the end of the test, corrosion behavior was investigated by weight loss measurements and changes in surface morphology. Fuels were analyzed by using TAN analyzer, FTIR, MOA (multi-element oil analyzer) to investigate acid concentration, oxidation level with water content and corrosive impurities respectively. Results showed that under the experimental conditions, pure copper was more susceptible to corrosion in biodiesel as compared to leaded bronze. (author)

  7. Development of quantitative atomic modeling for tungsten transport study Using LHD plasma with tungsten pellet injection

    International Nuclear Information System (INIS)

    Quantitative tungsten study with reliable atomic modeling is important for successful achievement of ITER and fusion reactors. We have developed tungsten atomic modeling for understanding the tungsten behavior in fusion plasmas. The modeling is applied to the analysis of tungsten spectra observed from currentless plasmas of the Large Helical Device (LHD) with tungsten pellet injection. We found that extreme ultraviolet (EUV) lines of W24+ to W33+ ions are very sensitive to electron temperature (Te) and useful to examine the tungsten behavior in edge plasmas. Based on the first quantitative analysis of measured spatial profile of W44+ ion, the tungsten concentration is determined to be n(W44+)/ne= 1.4x10-4 and the total radiation loss is estimated as ∼4 MW, of which the value is roughly half the total NBI power. (author)

  8. Structural and electrical properties in tungsten/tungsten oxide multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cacucci, Arnaud [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Potin, Valérie, E-mail: valerie.potin@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Imhoff, Luc [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Martin, Nicolas [Institut FEMTO-ST, UMR 6174 CNRS, Université de Franche-Comté, ENSMM, UTBM, 32 Avenue de l' observatoire, F-25044, BESANCON Cedex (France)

    2014-02-28

    Tungsten and tungsten oxide periodic nanometric multilayers have been deposited by DC reactive sputtering using the reactive gas pulsing process. Different pulsing periods have been used for each deposition to produce metal-oxide periodic alternations ranging from 3.3 to 71.5 nm. The morphology, crystallinity and chemical composition of these films have been investigated by transmission electron microscopy and energy-dispersive X-ray spectroscopy techniques. The produced multilayers exhibited an amorphous structure and the composition stability of WO{sub 3} sub-layers has been pointed out. Moreover, electrical properties have also been studied by the van der Pauw technique. It revealed a clear stability of resistivity versus temperature for almost all samples and an influence of the multilayered structure on the resistivity behavior. - Highlights: • W/WO{sub 3} multilayers with nanometric periods are produced by gas pulsing. • Multilayers are mainly amorphous and the oxide sub-layers composed of WO{sub 3}. • Crystallized inclusions of β-W and β-W{sub 3}O phases in metallic sub-layers • Metallic-like behavior with low temperature coefficient of resistance.

  9. Tribological properties of sputtered tungsten and tungsten nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Wong; K.M.; ShenY.G.; Wong; P.L.

    2001-01-01

    The surface roughness, hardness and tribological properties of tungsten (W) and tung-sten nitride (WNx) thin films prepared by dc magnetron sputtering and reactive magnetron sputter-ing in Ar-N2 gas mixtures have been studied using atomic force microscopy (AFM), nanoindenta-tion measurements and ball-on-disc wear testing. A pronounced surface roughness was observedonly for films under compressive strains. The surface was flat under tension but rough under com-pression. Similar hardness with value about 20 GPa were observed in the W and WNx (x=0.3)films. This is thought to be due to the fact the grains are restricted to a very small size in the coat-ings. The higher coefficients of friction (0.4 for W and 0.9 for WN0.3) suggest that WN0.3 is not theoptimum phase. Finally, discussions are made with tribological test results.

  10. Novel properties of Tungsten ditelluride

    Science.gov (United States)

    Liu, Huimei; National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Cent Collaboration

    Tungsten ditelluride has attracted intense research interest due to the recent discovery of its large unsaturated magnetoresistance up to 60 Tesla. By using density functional theory calculations, we qualitatively reproduced the observed spin texture. Since the spin texture would forbid back scatterings that are directly involved in the resistivity, we suggest that the SOC and the related spin and orbital angular momentum textures may play an important role in the anomalously large magnetoresistance of WTe2. Motivated by the presence of a small, sensitive Fermi surface of 5d electronic orbitals, we also boost the electronic properties by applying a high pressure, and introduce superconductivity successfully.

  11. A convenient thermal decomposition-co-reduction synthesis of nanocrystalline tungsten disilicide

    Indian Academy of Sciences (India)

    Jianhua Ma; Yihong Du; Yitai Qian

    2005-08-01

    Nanocrystalline WSi2 was synthesized by a thermal decomposition-co-reduction route via the reaction of anhydrous tungsten hexachloride and sodium fluorosilicate with metallic potassium in an autoclave at 650°C. X-ray powder diffraction pattern indicated that it was tetragonal WSi2. Transmission electron microscope image showed that it consisted of particles with an average diameter of about 50 nm. TGA and DTA indicated that it had good thermal stability below 600°C in air.

  12. Palaeoethnobotanical Data from the High Mountainous Early Bronze Age Settlement of Tsaghkasar-1 (Mt. Aragats, Armenia

    Directory of Open Access Journals (Sweden)

    Roman Hovsepyan

    2011-09-01

    Full Text Available Palaeoethnobotanical investigations suggest that at least part of the Early Bronze Age population of Tsaghkasar was settled and practiced agriculture in the high mountainous zone. People there appear to have cultivated hexa‐ and tetraploid wheats (probably bread wheat and emmer and barley (possibly hulled. Bronze Age agriculture in the Southern Caucasus differs from earlier and later period when cultivation of pulses, oil‐producing plants, and other plants was common. This emphasis on the cultivation and use of certain cereal grains at Early Bronze sites such as Tsaghkasar can tentatively be added to a constellation of practices associated with the Kura‐Araxes culture in the South Caucasus.

  13. Development of tungsten fibre-reinforced tungsten composites towards their use in DEMO—potassium doped tungsten wire

    Science.gov (United States)

    Riesch, J.; Han, Y.; Almanstötter, J.; Coenen, J. W.; Höschen, T.; Jasper, B.; Zhao, P.; Linsmeier, Ch; Neu, R.

    2016-02-01

    For the next step fusion reactor the use of tungsten is inevitable to suppress erosion and allow operation at elevated temperature and high heat loads. Tungsten fibre-reinforced composites overcome the intrinsic brittleness of tungsten and its susceptibility to operation embrittlement and thus allow its use as a structural as well as an armour material. That this concept works in principle has been shown in recent years. In this contribution we present a development approach towards its use in a future fusion reactor. A multilayer approach is needed addressing all composite constituents and manufacturing steps. A huge potential lies in the optimization of the tungsten wire used as fibre. We discuss this aspect and present studies on potassium doped tungsten wire in detail. This wire, utilized in the illumination industry, could be a replacement for the so far used pure tungsten wire due to its superior high temperature properties. In tensile tests the wire showed high strength and ductility up to an annealing temperature of 2200 K. The results show that the use of doped tungsten wire could increase the allowed fabrication temperature and the overall working temperature of the composite itself.

  14. History of a Bronze Age tell and its environment

    Science.gov (United States)

    Kovács, Gabriella; Füleky, György; Vicze, Magdolna

    2016-04-01

    Százhalombatta-Földvár is the most excessively researched Bronze Age tell site in Hungary. Parallel to the investigation of the settlement structure and activity patterns the changes of the landscape and the effect of human alteration is also studied. Significant changes of the landscape can be detected from the Bronze Age until the recent natural and cultural heritage protection of the area. Archaeological, soil analytical and thin section soil micromorphological methods are used to reconstruct the past 4000 years of the tell and its immediate surroundings. Prior to the Bronze Age the area was covered by forest vegetation, so the initial settling could only be realised after deforestation (2000 BC). The result of the soil corings and the prepared soil thin sections are solid proves of this action. It also became evident that at some areas - so far it seems that at locales where house floors were laid for the very first time - even the topsoil was removed so intensively that only the B horizon of the relict forest soil can be found. This observation needs to be further tested outside the habitation area to define the horizontal extension of the forest clearance and the topsoil removal. The northern side of the settlement is bordered by a natural erosion gully. At 2000 BC it was just a natural depression, but by 1500 BC it was deepened to serve as a fortification ditch. Around 1200 BC the ditch started to be filled in and by 1000 BC it was refilled to such an extent that its surface was utilised again. At about 600 BC (Late Iron Age) a smaller inner rampart was erected on the southern side of the ditch for inner separation. Not much is known about the Roman period of this area (200 AD) but the remnants of a watchtower indicate their presence. During the 18th century AD the area was used for grape cultivation and later for hobby gardens up until the protection of the area in the late 20th century. Since then species of the original vegetation started to grow back

  15. Selective tungsten deposition: Temperature-programmed studies on silicon, silicon dioxide, and tungsten surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hindman, G.T.

    1989-01-01

    Selective tungsten chemical vapor deposition (CVD) is a technique which has shown considerable promise for the semiconductor manufacturing industry due to tungsten's physical properties and its ability to be deposited in a spatially selective manner. Routine employment of selective tungsten deposition has been impeded by a lack of knowledge about processes by which selectivity is lost. In order to better understand the cause of selectivity loss and the chemistry of selective tungsten CVD, the interactions of WF{sub 6} on SiO{sub 2}, Si, and W surfaces were studied in ultra high vacuum (UHV) using Temperature Programmed Reaction Spectroscopy. These experiments revealed that WF{sub 6} is capable of reacting with a native oxide surface even at low temperatures. Tungsten oxyfluorides or silicon oxyfluorides desorption signals were not observed from either thick thermal or thin native oxide surfaces. On Si(100) multiple overlapping WF{sub 6} desorption peaks were observed. These chemisorption peaks shifted to higher temperatures with increasing exposure, and are believed to be due to the decomposition of a W-Si-F corrosion layer. Hydrogen did not adsorb on silicon surfaces containing appreciable amounts of tungsten. Tungsten and silicon rapidly interdiffused in tungsten films grown in situ by silicon reduction. Silicon on or in these in situ W films was more reactive than clean, tungsten-free silicon. Experiments on polycrystalline tungsten revealed that WF{sub 6} adsorption is partially irreversible.

  16. Hidden Sodium

    Centers for Disease Control (CDC) Podcasts

    2013-03-04

    In this podcast, learn about reducing sodium intake by knowing what to eat and the main sources of sodium in the diet. It's important for a healthy lifestyle.  Created: 3/4/2013 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 3/4/2013.

  17. Environmental fate of tungsten from military use

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Jay L. [Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, New Hampshire, 03755 (United States)], E-mail: Jay.L.Clausen@erdc.usace.army.mil; Korte, Nic [1946 Clover Ct., Grand Junction, Colorado, 81506 (United States)

    2009-04-01

    This manuscript describes the distribution, fate and transport of tungsten used in training rounds at three small arms ranges at Camp Edwards on the Massachusetts Military Reservation (MMR), USA. Practice with tungsten/nylon rounds began in 2000 subsequent to a 1997 US Environmental Protection Agency ban on training with lead. Training with the tungsten rounds was halted in 2005 because of concerns regarding tungsten's environmental mobility and potential toxicity. This study, therefore, examines how tungsten partitions in the environment when fired on a small arms training range. Soil sampling revealed surface soil concentrations, highest at the berm face, up to 2080 mg/kg. Concentrations decreased rapidly with depth-at least by an order of magnitude by 25 cm. Nonetheless, tungsten concentrations remained above background to at least 150 cm. Pore-water samples from lysimeters installed in berm areas revealed a range of concentrations (< 1-400 mg/L) elevated with respect to background although there was no discernable trend with depth. Groundwater monitoring well samples collected approximately 30 m below ground surface showed tungsten (0.001-0.56 mg/L) attributable to range use.

  18. Cavitation erosion behavior of nickel-aluminum bronze weldment

    Institute of Scientific and Technical Information of China (English)

    李小亚; 闫永贵; 许振明; 李建国

    2003-01-01

    Cavitation erosion behavior of nickel-aluminum bronze(NAB)weldment in 3.5% NaCl aqueous solution was studied by magnetostrictive vibratory device for cavitation erosion.The results show that cavitation erosion resistance of the weld zone(WZ)of the weldment is superior to that of the base metal.SEM observation of eroded specimens reveals that the phases undergoing selective attack by the stress of cavitation erosion at the early stage of cavitation erosion are:martensite in the WZ,α phase in the heat-affected zone(HAZ)and eutectoidal phase in the base metal; the microcracks causing cavitation damage initiate at the phase boundaries.

  19. LAMQS analysis applied to ancient Egyptian bronze coins

    International Nuclear Information System (INIS)

    Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.

  20. LAMQS analysis applied to ancient Egyptian bronze coins

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, L., E-mail: lorenzo.torrisi@unime.i [Dipartimento di Fisica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Caridi, F.; Giuffrida, L.; Torrisi, A. [Dipartimento di Fisica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Mondio, G.; Serafino, T. [Dipartimento di Fisica della Materia ed Ingegneria Elettronica dell' Universita di Messina, Salita Sperone, 31, 98166 Messina (Italy); Caltabiano, M.; Castrizio, E.D. [Dipartimento di Lettere e Filosofia dell' Universita di Messina, Polo Universitario dell' Annunziata, 98168 Messina (Italy); Paniz, E.; Salici, A. [Carabinieri, Reparto Investigazioni Scientifiche, S.S. 114, Km. 6, 400 Tremestieri, Messina (Italy)

    2010-05-15

    Some Egyptian bronze coins, dated VI-VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified.

  1. Dietary sodium

    DEFF Research Database (Denmark)

    Graudal, Niels

    2015-01-01

    The 2013 Institute of Medicine (IOM) report "Sodium Intake in Populations: Assessment of Evidence" did not support the current recommendations of the IOM and the American Heart Association (AHA) to reduce daily dietary sodium intake to below 2,300 mg. The report concluded that the population......-based health outcome evidence was not sufficient to define a safe upper intake level for sodium. Recent studies have extended this conclusion to show that a sodium intake below 2,300 mg/day is associated with increased mortality. In spite of this increasing body of evidence, the AHA, Centers for Disease...... Control (CDC), other public health advisory bodies, and major medical journals have continued to support the current policy of reducing dietary sodium....

  2. Elements inter-diffusion in the turning of wear-resistance aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Inter-diffusion of elements between the tool and the workpiece during the turning of aluminum bronze using high-speed steel and cemented carbide tools have been studied. The tool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turn a novel high strength, wear-resistance aluminum bronze without coolant and lubricant. Adhesion of workpiece materials was found on all tools' surface. The diffusion couples made of tool materials and aluminum bronze were prepared to simulate the inter-diffusion during the machining. The results obtained from tool wear samples were compared with those obtained from diffusion couples. Strong inter-diffusion between the tool materials and the aluminum bronze was observed in all samples. It is concluded that diffusion plays a significant role in the tool wear mechanism.

  3. University receives 2009 Governor's Environmental Excellence Bronze Medal for Campus Tree Tour 2008 Event

    OpenAIRE

    West, Hilary

    2009-01-01

    Virginia Tech received the 2009 Governor's Environmental Excellence Bronze Medal in the Environmental Project (Government) category for hosting the Campus Tree Tour 2008 tree planting event in Blacksburg on Oct. 21, 2008.

  4. The Bronze "Ding of Flourishing Olympic "for the Main Stadium of the 2008 Olympic Games

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The bronze "Ding of Flourishing Olympic" for the main stadium of the 2008Olympic Games has been completed by Yuda Group Company. The "Ding of Flourishing Olympic" was designed by Lanzhou Ludu Chunqiu Cultural Disseminating Co. Ltd.

  5. Influence Cr on Crystallization and the Phase Transformations of the Bronze BA1044

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2007-07-01

    Full Text Available The investigations were introduced in the paper, method of thermal and derivative analysis (TDA, the process of crystallization and phase transformation in the solid state of the aluminium bronze CuA110Fe4Ni4 (BA1044 and with the addition 0.3% Cr. Two intermetallic phase were identified in the microstructure of the bronze BA1044: κFel - rich in Fe and Cu and κFe2 - rich in Fe, and in the microstructure of the bronze BA1044+0.3 % Cr only one phase κFel - rich in Fe, Cu and Cr. The presence of chrome in the bronze BA1044 reduce size the primary crystals of the phase β, reduces the dynamics of the processes of thermal phase transformation in the solid state and lengthens the time their of duration.

  6. Fabrication and properties of tungsten heavy metal alloys containing 30% to 90% tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Gurwell, W.E.; Nelson, R.G.; Dudder, G.B.; Davis, N.C.

    1984-09-01

    In 1983, Pacific Northwest Laboratory conducted a survey of tungsten heavy metal alloys having lower-than-normal (<90%) tungsten content. The purpose of the work was to develop tougher, more impact-resistant high-density alloys for applications benefitting from improved mechanical properties. Tungsten heavy metal alloys of 30 to 90% tungsten content were fabricated and their mechanical properties measured. Although ultimate strength was essentially independent of tungsten content, lower tungsten-content alloys had lower yield stress, hardness, and density, and decidedly higher elongations and impact energies. Cold work was effective in raising strength and hardness but detrimental to elongation and impact energies. Precipitation hardening and strain aging raised hardness effectively but had less influence on other mechanical properties. 34 figures, 7 tables.

  7. Rapid and direct determination of percentage tungsten in tantalum-10% tungsten alloy by Wavelength Dispersive X-Ray Fluorescence Spectrometry

    International Nuclear Information System (INIS)

    A method for rapid and direct determination of percentage tungsten in tungsten-tantalum alloy by Wavelength Dispersive X-Ray Fluorescence Spectrometry has been developed for the routine determination of tungsten in tantalum-10% tungsten alloy samples. A RSD of < 1% is obtained in the technique. (author)

  8. Characterization of nanometer tungsten powders

    Institute of Scientific and Technical Information of China (English)

    LI Huiqian; LIN Tao; SHAO Huiping; WU Chengyi; GUO Zhimeng; LUO Ji

    2008-01-01

    Three types of tungsten powders were prepared by hydrogen reduction of three precursor powders at low temperature,which were used as samples,and were then characterized by Brunauer-Emmer-Teller (BET) method,scanning electron microscopy (SEM),transmission electronic microscopy (TEM),small angle X-ray scattering (SAXS),and field-emission scanning electron microscopy (FESEM) respectively.The results showed that although BET and SEM could not characterize the particle size of nanometer powders,they were important means of assistance to exclude non-nanometer powders.TEM and FESEM could directly measure the particle size of nanometer powders,but this needs a lot of time,to count the average particle size and particle size distribution.SAXS could not describe the state of agglomeration.By the combination of FESEM and SAXS,the particle size,particle size distribution,and particle shape of nanorneter powders could be preciscly characterized.

  9. Tungsten Ditelluride: a layered semimetal

    Science.gov (United States)

    Lee, Chia-Hui; Silva, Eduardo Cruz; Calderin, Lazaro; Nguyen, Minh An T.; Hollander, Matthew J.; Bersch, Brian; Mallouk, Thomas E.; Robinson, Joshua A.

    2015-06-01

    Tungsten ditelluride (WTe2) is a transition metal dichalcogenide (TMD) with physical and electronic properties that make it attractive for a variety of electronic applications. Although WTe2 has been studied for decades, its structure and electronic properties have only recently been correctly described. We experimentally and theoretically investigate the structure, dynamics and electronic properties of WTe2, and verify that WTe2 has its minimum energy configuration in a distorted 1T structure (Td structure), which results in metallic-like transport. Our findings unambiguously confirm the metallic nature of WTe2, introduce new information about the Raman modes of Td-WTe2, and demonstrate that Td-WTe2 is readily oxidized via environmental exposure. Finally, these findings confirm that, in its thermodynamically favored Td form, the utilization of WTe2 in electronic device architectures such as field effect transistors may need to be reevaluated.

  10. Facile Preparation of Molybdenum Bronzes as an Efficient Hole Extraction Layer in Organic Photovoltaics.

    Science.gov (United States)

    Wang, Jiantai; Zhang, Jun; Meng, Bin; Zhang, Baohua; Xie, Zhiyuan; Wang, Lixiang

    2015-06-24

    We proposed a facile and green one-pot strategy to synthesize Mo bronzes nanoparticles to serve as an efficient hole extraction layer in polymer solar cells. Mo bronzes were obtained through reducing the fractional self-aggregated ammonium heptamolybdate with appropriate reducing agent ascorbic acid, and its optoelectronic properties were fully characterized. The synthesized Mo bronzes displayed strong n-type semiconductor characteristics with a work function of 5.2-5.4 eV, matched well with the energy levels of current donor polymers. The presented gap states of the Mo bronzes near the Fermi level were beneficial for facilitating charge extraction. The as-synthesized Mo bronzes were used as hole extraction layer in polymer solar cells and significantly enhanced the photovoltaic performance and stability. The power conversion efficiency was increased by more than 18% compared with the polyethylene dioxythiophene:polystyrenesulfonate-based reference cell. The excellent performance and facile preparation render the as-synthesized solution-processed Mo bronzes nanoparticles a promising candidate for hole extraction layer in low-cost and efficient polymer solar cells.

  11. Investigating Early/Middle Bronze Age copper and bronze axes by micro X-ray fluorescence spectrometry and neutron imaging techniques

    Science.gov (United States)

    Figueiredo, Elin; Pereira, Marco A. Stanojev; Lopes, Filipa; Marques, José G.; Santos, Joana P.; Araújo, M. Fátima; Silva, Rui J. C.; Senna-Martinez, João C.

    2016-08-01

    Micro X-ray fluorescence (micro-XRF) analysis and neutron imaging techniques, namely 2D radiography and 3D tomography, have been applied for the study of four metal axes from the Early/Middle Bronze Age in Western Iberia, a period characterized by a metallurgical change in the use of copper to bronze. Micro-XRF analysis has shown that one of the axes was produced in copper with some arsenic while the other three were produced in a copper-tin alloy (bronze) with variable tin contents and some arsenic and lead. Neutron radiography and tomography were applied to study internal heterogeneities of the axes in a non-invasive way since the specificities of neutron interaction with matter allow a suitable penetration of these relatively thick copper-based objects when compared to the use of a conventional X-ray radiography. Neutron imaging allowed the visualization of internal fissures and pores and the evaluation of their distribution, size and shape. Relevant information for the reconstruction of ancient manufacturing techniques was gathered, revealing that one ax was produced with the mold in an angle of ≈ 25°, probably to facilitate gas escape during metal pouring. Also, information regarding physical weaknesses of the axes was collected, providing relevant data for their conservation. The combination of these non-destructive techniques allowed the evaluation of the metal composition and the internal structure of the axes. Micro-XRF allowed the distinction among copper and bronze axes, and provided data about the composition of early bronzes for which data is scarce. The neutron imaging study allowed for the first time the visualization of internal heterogeneities in early bronze axes, namely pores and large voids, providing relevant information for the reconstruction of ancient manufacturing techniques and raising pertinent information regarding physical weaknesses of these types of objects.

  12. Effect of process parameters on induction plasma reactive deposition of tungsten carbide from tungsten metal powder

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Tungsten carbide deposit was made directly from tungsten metal powder through the reaction with methane in radio frequency induction plasma. Effect of major process parameters on the induction plasma reactive deposition of tungsten carbide was studied by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, water displacement method, and microhardness test. The results show that methane flow rate, powder feed rate, particle size, reaction chamber pressure and deposition distance have significant influences on the phase composition, density, and microhardness of the deposit. Extra carbon is necessary to ensure the complete conversion of tungsten metal into the carbide.

  13. Visible light photoinactivation of bacteria by tungsten oxide nanostructures formed on a tungsten foil

    Energy Technology Data Exchange (ETDEWEB)

    Ghasempour, Fariba [Plasma Physics Research Centre, Science and Research Branch, Islamic Azad University, P.O. Box 147789-3855, Tehran (Iran, Islamic Republic of); Azimirad, Rouhollah [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Amini, Abbas [School of Computing, Engineering and Mathematics, University of Western Sydney, Kingswood, NSW 2751 (Australia); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2015-05-30

    Highlights: • Synthesis of tungsten oxide nano/micro-structures on W foils using KOH as a catalyst. • Strong antibacterial activity of tungsten oxide nanorods under visible light irradiation. • Decrease in photoinactivation of bacteria on tungsten oxide nano/micro-rods doped by potassium. - Abstract: Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400–800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50–90 nm and crystalline phase of WO{sub 3}) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K{sub 2}W{sub 6}O{sub 19} crystalline phase were formed on the foils. The WO{sub 3} nanorods showed a strong antibacterial property under visible light irradiation, corresponding to >92% bacterial inactivation within 24 h irradiation at room temperature, while the K{sub 2}W{sub 6}O{sub 19} microrods formed at 800 °C could inactivate only ∼45% of the bacteria at the same conditions.

  14. Nanostructured Tungsten Materials by Chemical Methods

    OpenAIRE

    Wahlberg, Sverker

    2011-01-01

    Tungsten based-materials are used in many different technical fields, particularly in applications requiring good temperature and/or erosion resistance. Nanostructuring of tungsten alloys and composites has the potential to dramatically improve the materials’ properties, enhancing the performance in present applications or enabling totally new possibilities. Nanostructured WC-Co composites have been the focus of researchers and industries for over two decades. New methods for powder fabricati...

  15. Tungsten carbide production from ore concentrates by molten salt-natural gas sparging treatment

    International Nuclear Information System (INIS)

    The U.S. Bureau of Mines conducted a bench-scale study to delineate the important parameters in a three-step process to produce commercial-quality tungsten carbide (WC) directly from tungsten minerals. In the process, tungsten concentrates of wolframite or wolframite and scheelite are decomposed at 1,0500C in a molten mixture of NcCl and Na2SiO3 that forms two immiscible phases. Tungsten, as sodium tungstate, reports to the halide phase and is separated from the gangue constituents, which report to the silicate phase. After decanting to separate the two phases, natural gas is sparged into the molten halide phase a 1,0700C. Submicrometer crystals of WC are initially produced. These crystals grow into thin triangular-shaped plates up to 100 μm on a side or into popcorn-shaped conglomerates. Sparged WC was examined for its suitability for use in sintered carbide products. In physical evaluations, sparged WC ground to an average particle size of 1.52 μm and compacted with 10 pct Co binder into standard 6-by 22-mm test bars had a density of 14.35 and a Rockwell A hardness of 89.6. This compared favorably with 14.39 and 89.7 respectively, for test bars made from a standard commercial 1.52-μm WC powder. Test bars made from Bureau of Mines WC had no ''C'' porosity or eta phase

  16. Electrolytic preparation of vanadium(5) oxide from oxovanadium(4) sulfate solution in the presence of sodium ions

    International Nuclear Information System (INIS)

    Influence of anodic current density, pH value and reagents concentration on the character of anodic processes, current efficiency and properties of deposits during electrolytic deposition of vanadium(5) oxide from aqueous solutions of oxovanadium(4) sulfate in the presence of sodium ions was studied. It was ascertained that in the presence of sodium ions some deposits are formed on the anode, which differ qualitatively from the ones prepared from solutions without additions. According to data of X-ray phase analysis the sediments after annealing at 500 deg C for 5-7 h were sodium-vanadium bronze of NaxV2O5 composition, featuring elevated electrochemical activity

  17. 高纯六氟化钨制备工艺研究%Preparation Technology of High Purity Tungsten Hexafluoride

    Institute of Scientific and Technical Information of China (English)

    陈志刚; 陈财华; 冯振雷

    2014-01-01

    介绍了利用氟气与钨粉为原料制备高纯六氟化钨的工艺方法和设备体系。其过程是利用电解槽电解氟氢化钾制取氟气,并采用氟化钠吸附配合深冷工艺纯化氟气,净化后的氟气与固定床里的钨粉在一定温度条件下反应合成初级六氟化钨,通过低温冷凝回收,收集的初级六氟化钨经过固化后抽真空排轻等方法进行初步提纯,然后将初步提纯的产品蒸馏至填料式精馏塔内进行深度提纯,经过多步提纯后的成品六氟化钨纯度可达99.999%以上。%This paper introduces the processing and equipment system for high-purity tungsten hexafluoride using fluorine gas and tungsten powder as raw materials. Electrolytic cell is applied to prepare fluorine gas by electrolyzing the potassium bifluoride. Sodium fluoride adsorption with cryogenic mixture is used to purify the fluorine gas. Purified fluorine gas reacts with tungsten powder to synthesize the impure tungsten hexafluoride in the fixed bed reactor at a certain temperature. The impure tungsten hexafluoride is obtained by low-temperature condensation. Curing and vacuuming technologies are performed on impure tungsten hexafluoride use to remove the volatile impurity. Filler type distillation column is utilized to further purify by monitoring the distillation products intermittently to prevent unqualified products collection. The results show that the purity of tungsten hexafluoride reaches 99.999%.

  18. Flux pinning in bronze-processed Nb3Sn wires

    International Nuclear Information System (INIS)

    The scaling law derived by Kramer for magnetic flux pinning in high magnetic fields was examined for its applicability to the magnetic field dependence of critical-current densities in the bronze processed monofilamentary Nb3Sn wires. From this it was concluded that: (1) its prediction for the form of the dependence of critical current on magnetic field and grain size [/J vector /sub c/ x H vector/ approx. h/sup 1/2/(1-h)2(1-a0√rho)-2] was found to be very good in most cases including wires with very small Nb3Sn grains (approx. 400 A). It was found very useful in comparison of J/sub c/ for different wires and in extrapolating to obtain H/sub c2/ for these wires. (2) However, it could not account consistently for the anisotropy in critical current of a tape which was measured with H applied perpendicular and parallel to the tape face. (3) The values of kappa1 which were determined with the scaling law were too small by a factor of 2 to 3, and the trend in the variation with heat-treating time was opposite to that which is reasonably to be expected. That the behavior of kappa1 is thus seriously in contradiction with the expected behavior for Nb3Sn suggests basic faults in the derivation of the scaling equation for critical currents at high magnetic fields

  19. Exploring the bronzing effect at the surface of ink layers

    Science.gov (United States)

    Hébert, Mathieu; Mallet, Maxime; Deboos, Alexis; Chavel, Pierre; Kuang, Deng-Feng; Hugonin, Jean-Paul; Besbes, Mondher; Cazier, Anthony

    2015-03-01

    We investigate the optical phenomenon responsible for the colored shine that sometimes appears at the surface of ink layers in the specular direction, often called bronzing or gloss differential. It seems to come from the wavelength-dependent refractive index of the ink, which induces a wavelength-dependent reflectance of the ink-air interface. Our experiments on cyan and magenta inkjet inks confirm this theory. Complex refractive indices can be obtained from measurements of the spectral reflectance and transmittance of a transparency film coated with the ink. We propose a correction of the classical Clapper-Yule model in order to include the colored gloss in the prediction of the spectral reflectance of an inked paper. We also explored effects of scattering by the micrometric or nanometric roughness of the ink surface. The micrometric roughness, easy to model with a geometrical optics model, can predict the spreading of the colored gloss over a large cone. Electromagnetic models accounting for the effect of the nanometric roughness of the surface also predict the attenuation of short wavelengths observed under collimated illumination.

  20. Corrosion of Bronzes by Extended Wetting with Single versus Mixed Acidic Pollutants

    Directory of Open Access Journals (Sweden)

    Liliana Gianni

    2014-04-01

    Full Text Available The corrosion of bronzes was examined in the context of single-acid versus mixed-acid (as in urban acid rain solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes. The kinetics of corrosion and the properties of the resulting patinas were monitored weekly by electrochemical impedance spectroscopy and open-circuit potential measurements. The sizes and appearances of the corrosion products were monitored and used to estimate the progress of the corrosion, whose crystalline structures were visualized using scanning electron microscopy with energy dispersive spectroscopy, identified by X-ray diffraction, and characterized by spectrocolorimetry. The electrochemical measurements demonstrated that greater damage (in terms of color change and corrosion product formation did not correspond to deficiencies in protection. The mixed-acid solution did not corrode the bronzes, as would be expected from the additive effects of the single acids. The postulated mechanisms of metal dissolution appear to be specific to a particular bronze alloy, with the tin component playing an important role.

  1. Dating simple flakes: Early Bronze Age flake production technology on the Middle Euphrates Steppe, Syria

    Directory of Open Access Journals (Sweden)

    Yoshihiro Nishiaki

    2014-03-01

    Full Text Available Aceramic flint scatters, comprising very crude cores or flakes and no formalised tools, are frequently found on the Middle Euphrates steppe of northern Syria. Previous studies suggest that many of them are residues of short-term activities by the nomads or shepherds of the Early Bronze Age. In order to verify this interpretation, a more precise chronological framework needs to be established for the Early Bronze Age lithic industry. This paper analyses stratified flake assemblages of the Early Bronze Age at Tell Ghanem al-Ali, a securely radiocarbon-dated settlement on the Middle Euphrates, and examines which occupation level yields assemblages most similar to those of the steppe. Results demonstrate that the lithic industry of this period underwent significant diachronic changes in terms of core reduction technology. Based on the chronological framework developed at Tell Ghanem al-Ali, the steppe assemblages in question can be assigned to different phases of the Early Bronze Age. This finding will help identify processes at the beginning of the extensive exploitation of the steppe, which is regarded as one of the most important socioeconomic changes that occurred among Early Bronze Age communities of the Middle Euphrates.

  2. Growth inhibition by tungsten in the sulfur-oxidizing bacterium Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Negishi, Atsunori; Muraoka, Tadashi; Maeda, Terunobu; Takeuchi, Fumiaki; Kanao, Tadayoshi; Kamimura, Kazuo; Sugio, Tsuyoshi

    2005-11-01

    Growth of five strains of sulfur-oxidizing bacteria Acidithiobacillus thiooxidans, including strain NB1-3, was inhibited completely by 50 microM of sodium tungstate (Na(2)WO(4)). When the cells of NB1-3 were incubated in 0.1 M beta-alanine-SO(4)(2-) buffer (pH 3.0) with 100 microM Na(2)WO(4) for 1 h, the amount of tungsten bound to the cells was 33 microg/mg protein. Approximately 10 times more tungsten was bound to the cells at pH 3.0 than at pH 7.0. The tungsten binding to NB1-3 cells was inhibited by oxyanions such as sodium molybdenum and ammonium vanadate. The activities of enzymes involved in elemental sulfur oxidation of NB1-3 cells such as sulfur oxidase, sulfur dioxygenase, and sulfite oxidase were strongly inhibited by Na(2)WO(4). These results indicate that tungsten binds to NB1-3 cells and inhibits the sulfur oxidation enzyme system of the cells, and as a result, inhibits cell growth. When portland cement bars supplemented with 0.075% metal nickel and with 0.075% metal nickel and 0.075% calcium tungstate were exposed to the atmosphere of a sewage treatment plant containing 28 ppm of H(2)S for 2 years, the weight loss of the portland cement bar with metal nickel and calcium tungstate was much lower than the cement bar containing 0.075% metal nickel.

  3. Scandia doped tungsten matrix for impregnated cathode

    Institute of Scientific and Technical Information of China (English)

    WANG Jinshu; WANG Yanchun; LIU Wei; LI Hongyi; ZHOU Meiling

    2008-01-01

    As a matrix for Sc-type impregnated cathode,scandia doped tungsten with a uniform ldistribution of SC2O3 was obtained by powder metallurgy combined with the liquid-solid doping method.The microstructure and composition of the powder and the anti-ion bombardment behavior of scandium in the matrix were studied by means of SEM,EDS,XRD,and in-situ AES methods.Tungsten powder covered with scandium oxide,an ideal scandium oxide-doped tungsten powder for the preparation of Sc-type impregnated cathode,was obtained using the liquid-solid doping method.Compared with the matrix prepared with the mechanically mixed powder of tungsten and scandium oxide,SC2O3-W matrix prepared with this kind of powder had smaller grain size and uniform distribution of scandium.Sc on the surface of Sc2O3 doped tungsten mauix had good high temperature stability and good anti-ion bombardment capability.

  4. Electrocatalytic Activity of Tungsten Trioxide Micro-spheres, Tungsten Carbide Microspheres and Multi-walled Carbon Nanotube-tungsten Carbide Composites

    Institute of Scientific and Technical Information of China (English)

    LU Hongzhi; YAN Taining

    2009-01-01

    Tungsten trioxide micropheres were prepared by spray pyrolysis, and tungsten carbidemicrospheres were produced by spray pyrolysis-low temperature reduction and carbonization technology.Multi-walled carbon nanotube-tungsten carbide composites were prepared by the continuous reductionand carbonization process using multi-walled carbon nanotubes (MWCNTs) and WO_3 precursor by mo-lecular level mixing and calcination. The morphology and structure of the samples were characterized byscanning electron microscope and transmission electron microscope. Furthermore, the crystal phase was identified by X-ray diffraction. The electrocatalytic activity of the sample was analyzed by means of me-thanol oxidation. Tungsten carbide microspheres were catalytic active for methanol oxidation reaction.Nevertheless tungsten trioxide microspheres and multi-walled carbon nanotube-tungsten carbide compos-ites were not catalytic active for methanol oxidation reaction. These results indicate that tungsten carbide micropheres are promising catalyst for methanol oxidation.

  5. Growth of tungsten oxide on carbon nanowalls templates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua, E-mail: wanghua@dlou.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023 (China); Su, Yan [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Chen, Shuo, E-mail: shuochen@dlut.edu.cn [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-03-15

    Highlights: ► Tungsten oxide deposited on carbon nanowalls by hot filament chemical vapor deposition technique. ► This composite has two-dimensional uniform morphology with a crystalline structure of monoclinic tungsten trioxide. ► Surface photoelectric voltage measurements show that this product has photoresponse properties. - Abstract: In the present work we present a simple approach for coupling tungsten oxide with carbon nanowalls. The two-dimensional carbon nanowalls with open boundaries were grown using plasma enhanced hot filament chemical vapor deposition, and the subsequent tungsten oxide growth was performed in the same equipment by direct heating of a tungsten filament. The tungsten oxide coating is found to have uniform morphology with a crystalline structure of monoclinic tungsten trioxide. Surface photoelectric voltage measurements show that this product has photoresponse properties. The method of synthesis described here provides an operable route to the production of two-dimensional tungsten oxide nanocomposites.

  6. Electroanalytical determination of tungsten and molybdenum in proteins.

    Science.gov (United States)

    Hagedoorn, P L; van't Slot, P; van Leeuwen, H P; Hagen, W R

    2001-10-01

    Recent crystal structure determinations accelerated the progress in the biochemistry of tungsten-containing enzymes. In order to characterize these enzymes, a sensitive determination of this metal in protein-containing samples is necessary. An electroanalytical tungsten determination has successfully been adapted to determine the tungsten and molybdenum content in enzymes. The tungsten and molybdenum content can be measured simultaneously from 1 to 10 microg of purified protein with little or no sample handling. More crude protein samples require precipitation of interfering surface active material with 10% perchloric acid. This method affords the isolation of novel molybdenum- and tungsten-containing proteins via molybdenum and tungsten monitoring of column fractions, without using radioactive isotopes. A screening of soluble proteins from Pyrococcus furiosus for tungsten, using anion-exchange column chromatography to separate the proteins, has been performed. The three known tungsten-containing enzymes from P. furiosus were recovered with this screening.

  7. Mathematical Modelling of Process of Fluoration of Metal Tungsten

    Directory of Open Access Journals (Sweden)

    Brendakov Roman V.

    2016-01-01

    Full Text Available Wide use of products from metal tungsten in various branches of a national economy is caused by unique properties of this metal. By means of physical and mathematical modelling of process of receiving gaseous hexafluoride of tungsten it is possible to solve a problem of creation of import-substituting technology of processing of metal tungsten. The fluoride technology of processing of tungsten allows to put various coverings and to make products of tungsten of a various form which can't be received by traditional methods. Fluoride technology of processing of tungsten it is possible to present in the form sequences of two processes, process of fluorination of metal tungsten and process of restoration of fluorides of tungsten hydrogen.

  8. 青铜乐器自名研究%A Study of the Names Inscribed on Bronze Musical Instruments

    Institute of Scientific and Technical Information of China (English)

    陈双新

    2001-01-01

    Based on his studies of the bronze musical instruments, the author analyses the inscriptions referring the self-named modifiers and tries to give them new explanations. The study is important to understand the function and values of the bronze musical instruments.

  9. Principles of the alloying of tungsten and development of the manufacturing technology for the tungsten alloys

    International Nuclear Information System (INIS)

    Tungsten alloys (Tm = 3410 oC) are intended for service in reducing and neutral media or in vacuum at temperatures and loads that are too high to be suitable for alloys based on more low-melting metals. The disadvantage of tungsten as bcc transition metal of IV group is its susceptibility to cold brittleness (low plasticity at temperatures below the ductile-brittle transition temperature Td/b). The aim of the present work was to develop the principle of the design of tungsten-based structural alloys and their manufacturing and treatment processes providing the production of high-strength high-temperature tungsten-based materials having a satisfactory low-temperature plasticity and workability both in thin sections and in large-scale articles. To achieve this goal, it was necessary to solve the following problems: 1. to elaborate the methods controlling the cold brittleness of tungsten with allowance for the factors responsible for this damage and with reference to the production method; 2. to elaborate the methods improving strength and high-temperature strength with allowance for the acceleration of diffusion processes in bcc metals at temperatures above 0.6 Tm and for the absence of 'more sluggish' alloying elements (AE) than the most refractory metal tungsten; 3. to elaborate the methods of the uniform distribution of AE and strengthening phases in conventionally melted or powder tungsten alloys for the stabilization of required phase composition and structural state and the required combination of the properties of tungsten-based materials; 4. to elaborate the possibility and reasonability to use one ore another type of alloying and microstructure formation upon the manufacturing and thermoplastic treatment with reference to the type and destination of semiproducts or articles produced from tungsten-based alloys or composites. (author)

  10. Bibliographic study on the recovery tungsten

    International Nuclear Information System (INIS)

    Because of the importance of tungsten as a metal and its availability in Algerian ores, many prospective missions have been organized in the hoggar region since the country has recovered its independence and autonomy in order to extract the metal. The tungsten ores which are found in the hoggar are essentially composed of wolframite. With a 100000 tons per year as a production rate and a content of W03 + Sn very rarely greater than 1% the hoggar occupies a honorrable place among the regions which are well know throughout the world to produce tungsten. The are valorization technique which has been developed is mainly a gravimetric in humid media. It consists of a local preconcentration giving birth to a preconcentrated sample that is afterwards transferred to and dealt with a central plant where the final product is obtained

  11. TPV Systems with Solar Powered Tungsten Emitters

    International Nuclear Information System (INIS)

    A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at λ > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed

  12. Preliminary study on corrosion layers of unearthed bronzes relics of Xizhou dynasty, China

    International Nuclear Information System (INIS)

    Engineering barrier for HLW repository is composed of vitrified waste, canister and buffer/backfill material. Assessment of the applicability of metal as candidate materials of canister for HLW has been conducted in some countries.. Many bronze relics in Xizhou Dynasty, China, dated from more than 3000 years ago, have been preserved perfectly. The study on the corrosion of the bronze relics would contribute to the material selection and design of canister for HLW. The corrosion products of ancient bronzes consist of copper carbonate hydrate, lead carbonate, copper oxides etc. The corrosion mechanism of the substrate were mainly characterized by electrochemical corrosion, whereas the corrosion mechanism of surface layers was characterized by direct chemical corrosion and electrochemical corrosion. (author)

  13. DEGRADATION WORKS OF MONUMENTAL ART CAST BRONZE UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS

    Directory of Open Access Journals (Sweden)

    Delia NICA-BADEA

    2012-11-01

    Full Text Available Intensive pollution, combined with the lack of conservation of monuments exposed to these environments make the main cause of deterioration of cultural objects to atmospheric corrosion metal. This paper proposes a study of the main factors leading to degradation Bronze alloy, cast bronze monuments exposed to open atmosphere: corrosive environmental factors, stability and products of corrosion of bronze. In general, all corrosion products present on a metal surface are indicated as 'skate', can be composed of single-layer or multilayer products. The paper also includes a case study on the influence of environmental factors on degradation Matthias monument statue in Cluj-Napoca, Romania. Visual inspection of the monument informs us that have white spots, gray, reddish not consistent with the base color green patina, surfaces showing depigmentation, the rain washed areas, crystallization, deposition of air-borne particles.

  14. Tool wear mechanism in turning of novel wear-resisting aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    倪东惠; 夏伟; 张大童; 郭国文; 邵明

    2003-01-01

    Tool wear and wear mechanism during the turning of a wear-resisting aluminum bronze have been stud-ied. Tool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turn a novelhigh strength, wear resisting aluminum bronze without coolant and lubricant. Adhesion of workpiece materials wasfound on tool's surface. Under the turning condition used in this study major wear mechanisms for turning aluminumbronze using M2 high-speed steel tool are diffusion wear, adhesive wear and plastic deformation and shear on thecrater. Partial melting of high-speed steel on the rake plays a role in the tool wear also. Major wear mechanisms forturning aluminum bronze using YW1 cemented carbide tool are diffusion wear, attrition wear and sliding wear. Tocontrol the machining temperature is essential to reduce tool wear.

  15. The huastec region: a second locus for the production of bronze alloys in ancient mesoamerica.

    Science.gov (United States)

    Hosler, D; Stresser-Pean, G

    1992-08-28

    Chemical analyses of 51 metal artifacts, one ingot, and two pieces of intermediate processed material from two Late Post Classic archeological sites in the Huastec area of Eastern Mesoamerica point to a second production locus for copper-arsenic-tin alloys, copper-arsenic-tin artifacts, and probably copper-tin and copper-arsenic bronze artifacts. Earlier evidence had indicated that these bronze alloys were produced exclusively in West Mexico. West Mexico was the region where metallurgy first developed in Mesoamerica, although major elements of that technology had been introduced from the metallurgies of Central and South America. The bronze working component of Huastec metallurgy was transmitted from the metalworking regions of West Mexico, most likely through market systems that distributed Aztec goods. PMID:17742754

  16. Mesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Mesoporous films exhibit better electrochemical kinetics compared to the dense films. • Mesoporous films exhibit better reversibility compared to the dense films. • Li+cations disrupt WO3 network in a reversible way in the mesoporous film. • Li+ irreversibly intercalate in the voids of crystallites in the dense film. - Abstract: The intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics. In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and de-intercalation. According to chronoamperometric measurements, Li+ intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s). The electrochemical measurements (cyclic voltammetry and chronoamperometry) also showed worse reversibility for the dense film compared to the mesoporous film, giving rise to important Li+ trapping and remaining coloration of the film. Raman analysis showed that the mesoporous film provides more accessible and various W-O surface bonds for Li+ intercalation. On the contrary, in the first electrochemical insertion and de-insertion in the dense film, Li+ selectively reacts with a few surface W-O bonds and preferentially intercalates into pre-existing crystallites to form stable irreversible LixWO3 bronze

  17. The effects of chemical oxide on the deposition of tungsten by the silicon reduction of tungsten hexaflouride

    International Nuclear Information System (INIS)

    The effects of thin (chemical) oxide grown during the chemical cleaning of silicon wafers on the silicon reduction of tungsten hexaflouride have been investigated. Unlike tungsten deposition on samples without the chemical oxide, deposition thickness on those with the chemical oxide was found to be substantially thicker. Inspection by cross sectional SEM and TEM revealed the existence of micro-channels penetrating the tungsten film, reaching all the way from the surface of the film to the tungsten/silicon interface. These channels enable tungsten hexaflouride to reach the substrate, thus causing unlimited tungsten growth. Because the silicon surface participates directly in the reaction, it should be expected that the reaction itself be influenced by the chemical treatment of the surface prior to tungsten deposition. Under certain deposition conditions, and for properly prepared silicon surfaces, silicon reduction is known to result in self limiting tungsten deposition

  18. Ultra-broad band absorber made by tungsten and aluminium

    Science.gov (United States)

    Wang, Wei; Zhao, Ding; Li, Qiang; Qiu, Min

    2016-01-01

    A broadband absorber comprising tungsten cubic arrays, a alumina layer and a tungsten film, is numerically and experimentally investigated, which exhibits near-unity absorption of visible and near-infrared light from 400 nm to 1150 nm. Benefiting from high melting points of tungsten and alumina, this device has great application potential in solar cells and thermal emission.

  19. Tungsten potentiodynamic behaviour in sulfuric acid solutions

    International Nuclear Information System (INIS)

    The behaviour of a tungsten electrode to cyclic voltametry as a perturbation technique was studied. Tests were carried out in 1M H2SO4 (25.0 + - 0.2)0C and using a three electrode conventional cell. The electrode potential was measured in relation to a saturated calomel electrode connected to a Luggin capillary. The working electrode consisted of a tungsten wire, of spectroscopic purity, having 0.6 cm2 geometric area and a platinum counter-electrode. Considerations about the conditions and feasibility of using such an electrode for electrochemical and electrocatalytic studied are made. (C.L.B.)

  20. Microstructural evolution of tungsten oxide thin films

    International Nuclear Information System (INIS)

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  1. Bronze and Iron Age sites in Srem and the stratigraphy of Gomolava

    Directory of Open Access Journals (Sweden)

    Tasić Nikola

    2005-01-01

    Full Text Available Systematic excavation at Gomolava conducted almost interruptedly between 1953 and 1985 provided an almost full insight into the human occupation of the southern Pannonian Plain from the Early Neolithic to the successive arrival of Celts and Romans. This fact makes it possible for many of the excavated short-lived or horizontally-stratified settlements to be defined in relation to Gomolava's stratigraphic sequence. As a result, the paper attempts to establish a relative chronology for Bronze and Iron Age sites in the area between the Sava and Danube rivers. By way of illustration, it offers four maps suggesting synchronous developments. Thus Map 1 shows chronological parallelism between the Early Bronze Age layers and late Vučedol and Vinkovci sites (such as Pećine near Vrdnik, or Belegiš, Vojka and Batajnica belonging to the final Eneolithic and Early Bronze, while Map 2 shows synchronisms between Gomolava IVb-c and the Vinkovci layers at the sites of Gradina on the Bosut, Gradac at Belegiš, Petrovaradin Fortress, and Asfaltna Baza on the outskirts of Zemun. The end of the Bronze Age represented by Gomolava IVb1 to IVc is shown to be synchronous with the settlements, necropolises and hoard horizons of an Ha A1 and A2 date. Finally, Early Iron Age sites are easy to fit in with the Srem sites owing to systematic excavations at Gradina on the Bosut near Šid, Kalakača near Beška and numerous hoards of bronze artefacts marking a clear boundary between the Bronze and Early Iron Ages. At Gomolava this transition is reflected in horizons Va to Vd: the earliest is represented by black channeled pottery of the Gava type, while the other three are connected with the evolution of the Bosut-Basarabi complex.

  2. Dynamic characteristics of Great Bronze Buddha of Kamakura using microtremor

    International Nuclear Information System (INIS)

    The second largest bronze Buddha in Japan built in around 1250AD at Kamakura immediately above the focal region of the 1923 Kanto earthquake. Great Buddha of Kamakura has still remained basically its original shape, though it has been suffered several natural disasters as losing its hall. Especially, although the 1703 and 1923 Kanto earthquakes caused settlement and sliding of the basement over 0.3 m., the body has been not suffered serious damage. This statue was casted in order from the bottom with many joints. The joint between the head and the body was noticed because it is reinforced by FRP, Fiber Reinforced Plastic, at the time of the last major repair in 1961. And ingenuity was exercised to fence off the earthquake motion over 400 Gal with sliding the body on the basement, to reduce the load for the neck during earthquake. This is the first example of the earthquake isolation system for cultural properties in Japan. Over 50 years passed after the during earthquake motion, microtremor measurement was conducted. As a result of the primary investigation in 2009, the surrounding ground was estimated that liquefaction was occurred at the front and right sides of the basement and the basement suffered damage as settlement. However, it is considered that the propagation of the earthquake motion for the statue was interrupted because of the liquefaction. Thus, it seems that the damage for the statue itself was prevented because of namely the natural isolation system. Additional y in 2013 microtremor of the statue itself was measured for making clear the connection status between the body and the head.

  3. Spinal arthritis and physical stress at Bronze Age Harappa.

    Science.gov (United States)

    Lovell, N C

    1994-02-01

    This study examines joint changes in the vertebral skeleton in human remains excavated in 1987 and 1988 at Bronze Age Harappa, an urban center of the Indus Valley civilization. The sample consists of 23 complete skeletons from primary burial context, the partial remains of more than 69 other individuals, and hundreds of skeletal elements from secondary context, totalling 3,084 vertebral joint margins and articular surfaces. Marginal bone proliferation, pitting of articular surfaces, eburnation, and ankylosis were scored macroscopically for vertebral body margins and surfaces and posterior apophyseal facet joints. Marginal lipping is far more prevalent on the vertebral bodies than on the apophyseal facets and surface pitting is also more frequent on vertebral bodies although its expression is relatively low overall. Cervical vertebrae in this sample exhibit the same amount of marginal new bone and much more surface pitting of the vertebral bodies than do either thoracic or lumbar vertebrae; the cervical segment also exhibits the most severe expressions of both types of lesions. In addition, although the frequencies of cervical and lumbar posterior facet involvement are similar, the cervical facets exhibit much more severe lipping as well as the only cases of eburnation and ankylosis. Pitting of the posterior facets is most common in the lumbar segment, but the cervical examples are the only severe cases. It is proposed that the severe joint changes in the cervical spine result from trauma, perhaps accumulated microtrauma from activity stresses. There are no age or sex associated patterns in the frequency of arthritis although this result may be influenced by the small proportions of the total sample for which age and sex could be determined. PMID:8147433

  4. Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

    International Nuclear Information System (INIS)

    External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author)

  5. Symbolic metal bit and saddlebag fastenings in a Middle Bronze Age donkey burial.

    Directory of Open Access Journals (Sweden)

    Guy Bar-Oz

    Full Text Available Here we report the unprecedented discovery of the skeleton of a ritually interred donkey with a metal horse bit in association with its teeth and saddlebag fastenings on its back. This discovery in the Middle Bronze Age III sacred precinct (1700/1650-1550 BCE at Tel Haror, Israel, presents a unique combination of evidence for the early employment of equid harnessing equipment, both for chariot bridling (horse bit and pack animals (saddlebags. The ritually deposited donkey with its unique accoutrements advances our understanding of the broad social and religious significance of equids in the Levantine Bronze Age, previously known mainly from textual and iconographical sources.

  6. O bronze final na região de Mértola

    OpenAIRE

    BARROS, Pedro de

    2012-01-01

    Mértola fica localizada num local com boa defensibilidade, no final do longo estuário do Rio Guadiana no Sudoeste Peninsular entre uma peneplanicíe e os vales encaixados, onde as linhas de água subsidiárias têm o seu percurso. A ocupação do Bronze Final de Mértola é revelada pela presença de cerâmica com ornatos brunidos, formas cerâmicas manuais, cerâmica frequentemente designada "tipo Carambolo" e um exemplar de foice em bronze do "tipo Rocanes". Apesar de serem poucos os elementos, estes r...

  7. Pressure Effects on Solid State Phase Transformation of Aluminium Bronze in Cooling Process

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-Yan; CHEN Yan; LIU Yu-Wen; LI Fei; LIU Jian-Hua; PENG Gui-Rong; WANG Wen-Kui

    2009-01-01

    Effects of high pressure (6 GPa) on the solid state phase transformation kinetic parameters of aluminum bronze during the cooling process are investigated, based on the measurement and calculation of its solid state phase transformation temperature, duration and activation energy and the observation of its microstructures. The results show that high pressure treatment can reduce the solid phase transformation temperature and activation energy in the cooling process and can shorten the phase transformation duration, which is favorable when forming fine-grained aluminum bronze.

  8. Bronze Age moss fibre garments from Scotland – the jury’s out

    OpenAIRE

    Harris, Susanna; Gleba, Margarita

    2015-01-01

    In the light of recent discoveries of early to middle Bronze Age burials with mats and fibrous material in Scotland, for example at Langwell farm and Forteviot, it was deemed timely to re-evaluate earlier finds of this period, several of which were discovered and initially reported on nearly a century ago. As part of this research it was noted that three Bronze Age finds from the old literature were reported as clothing or shrouds made of hair moss (Polytrichum commune). Three of these are r...

  9. Vegetation reconstruction of Bronze Age by using microscopic structure of charcoals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The microscopic structure of charcoals was determined in two sites of Bronze Age, Chifeng area by using the scanning electronic microscope. The results showed that these charcoals are all timbers of Mongolian oak (Quercus mongolica). It has powerful climatic indicative significance. Based on the assemblage of pollen composition, their eco-climatic index and character of community, the vegetation reconstruction of Bronze Age was obtained. The reconstruction showed that the zonal vegetation was Mongolian oak forest and Chinese pine forest in the loess hills in the Chifeng area, which suggested that the climatic condition was warmer and wetter at that time than present time.

  10. Symbolic Metal Bit and Saddlebag Fastenings in a Middle Bronze Age Donkey Burial

    Science.gov (United States)

    Bar-Oz, Guy; Nahshoni, Pirhiya; Motro, Hadas; Oren, Eliezer D.

    2013-01-01

    Here we report the unprecedented discovery of the skeleton of a ritually interred donkey with a metal horse bit in association with its teeth and saddlebag fastenings on its back. This discovery in the Middle Bronze Age III sacred precinct (1700/1650-1550 BCE) at Tel Haror, Israel, presents a unique combination of evidence for the early employment of equid harnessing equipment, both for chariot bridling (horse bit) and pack animals (saddlebags). The ritually deposited donkey with its unique accoutrements advances our understanding of the broad social and religious significance of equids in the Levantine Bronze Age, previously known mainly from textual and iconographical sources. PMID:23484046

  11. Nomadic pastoralism in the Early Bronze Age of the central Balkans evaluation of background knowledge

    Directory of Open Access Journals (Sweden)

    Porčić Marko

    2008-01-01

    Full Text Available The aim of the paper is to examine background knowledge about the orga­nizational properties of mobile pastoral groups in order to assess the likelihood of the existence of pastoral nomads in the Early Bronze Age in the central Balkans. The patterning found by A. L. Johnson (2002 is taken as a point of departure for the cross-cultural analysis conducted in this study. Johnson’s findings are in the main corroborated. Acquired knowledge about the workings of pastoral societies suggests that highly mobile pastoral groups should not be expected in the Early Bronze Age of the central Balkans.

  12. Formation and Oxidation of Hydrogen Molybdenum Bronze on platinum electrode in sulfuric acid solution

    Institute of Scientific and Technical Information of China (English)

    Jin LU; Jun Hua DU; Wei Shan Li; Jia Mo FU

    2004-01-01

    Hydrogen molybdenum bronze (HxMoO3) can be electrodeposited on platinum and oxidized in two steps to the hydrogen molybdenum bronze with less amount of hydrogen HyMoO3 (y

  13. Test Your Sodium Smarts

    Science.gov (United States)

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  14. Aluminum-tungsten fiber composites with cylindrical geometry and controlled architecture of tungsten reinforcement

    OpenAIRE

    Lucchese, Carl Joesph

    2010-01-01

    A aluminum matrix-W rod/wire structural material in support of DARPA initiative BAA 08-23 was developed and its density and mechanical strength ascertained, both being part of the DARPA matrices. Aluminum tubes and four 90 degree cross-ply tungsten fiber layers were arranged such that under extreme static pressure conditions the aluminum would viscoplastically flow into the tungsten arrangement to create a metal matrix composite. It was found that a cold isostatic process induced "Brazilian" ...

  15. Thermal cycling and high power density hydrogen ion beam irradiation of tungsten layers on tungsten substrate

    Science.gov (United States)

    Airapetov, A. A.; Begrambekov, L. B.; Gretskaya, I. Yu; Grunin, A. V.; Dyachenko, M. Yu; Puntakov, N. A.; Sadovskiy, Ya A.

    2016-09-01

    Tungsten layers with iron impurity were deposited on tungsten substrates modeling re-deposited layers in a fusion device. The samples were tested by thermocycling and hydrogen ion beam tests. Thermocycling revealed globule formation on the surface. The size of the globules depended on iron impurity content in the coating deposited. Pore formation was observed which in some cases lead to exfoliation of the coatings. Hydrogen ion irradiation lead to formation of blisters on the coating and finally its exfoliation.

  16. Electrospark doping of steel with tungsten

    Science.gov (United States)

    Denisova, Yulia; Shugurov, Vladimir; Petrikova, Elizaveta; Seksenalina, Malika; Ivanova, Olga; Ikonnikova, Irina; Kunitsyna, Tatyana; Vlasov, Victor; Klopotov, Anatoliy; Ivanov, Yuriy

    2016-01-01

    The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

  17. Joining of Tungsten Armor Using Functional Gradients

    International Nuclear Information System (INIS)

    The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

  18. Electrospark doping of steel with tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, Yulia, E-mail: yukolubaeva@mail.ru; Shugurov, Vladimir, E-mail: shugurov@opee.hcei.tsc.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); Petrikova, Elizaveta, E-mail: elizmarkova@yahoo.com [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Seksenalina, Malika, E-mail: sportmiss@bk.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Ivanova, Olga, E-mail: ivaov@mail.ru; Ikonnikova, Irina, E-mail: irinaikonnikova@yandex.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Kunitsyna, Tatyana, E-mail: kma11061990@mail.ru; Vlasov, Victor, E-mail: rector@tsuab.ru [National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); Tomsk State University of Architecture and Building, 2 Solyanaya Sq. Tomsk, 634003 (Russian Federation); Ivanov, Yuriy, E-mail: yufi55@mail.ru [Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, 634055, Russia, Tomsk, 2/3 Akademicheskiy Ave (Russian Federation); National Research Tomsk State University, 36 Lenin Str. Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Str. Tomsk, 634050 (Russian Federation)

    2016-01-15

    The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

  19. OPAL Example Segment of Silicon Tungsten Luminometer

    CERN Multimedia

    OPAL was one of the four experiments installed at the LEP particle accelerator from 1989 - 2000. The Silicon Tungsten Luminometer was part of OPAL's calorimeter which was used to measure the energy of particles. Most particles end their journey in calorimeters. These detectors measure the energy deposited when particles are slowed down and stopped.

  20. Titanium tungsten coatings for bioelectrochemical applications

    DEFF Research Database (Denmark)

    Wierzbicki, Rafal; Amato, Letizia; Łopacińska, J.;

    2011-01-01

    This paper presents an assessment of titanium tungsten (TiW) coatings and their applicability as components of biosensing systems. The focus is put on using TiW as an electromechanical interface layer between carbon nanotube (CNT) forests and silicon nanograss (SiNG) cell scaffolds. Cytotoxicity...

  1. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.3E11 protons @ 440 GeV are impinging on the target.

  2. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.85E11 protons @ 440 GeV are impinging on the target.

  3. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 2E11 protons @ 440 GeV are impinging on the target.

  4. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    HiRadMat facility of CERN/SPS

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 1.7E11 protons @ 440 GeV are impinging on the target.

  5. Proton Induced Effects on Tungsten Powder

    CERN Multimedia

    2012-01-01

    In the HRMT-10 experiment, that took place in HiRadMat facility of CERN/SPS, the effects of a high-power incident proton beam on a tungsten powder target were investigated. In this video, 2.64E11 protons @ 440 GeV are impinging on the target.

  6. Theory and practice of tungsten oxides reduction

    International Nuclear Information System (INIS)

    The paper provides for a critical analysis of a thermograviometric technique for determining the kinetics of tungsten oxides reduction. A mechanism of heterogeneous reduction is proposed which is called discrete-dispersion mechanism. Certain technical and economic data and results of industrial vertical continuous furnace testing are presented

  7. CVD coated tungsten powder composites. Part 2

    International Nuclear Information System (INIS)

    In work sponsored by the Army Materials Technology Laboratory (AMTL), the tungsten composite powders described in Part I were consolidated by hot isostatic pressing (HIP), liquid phase sintering (LPS), and the Ceracon process. THis paper describes the results of consolidation, microstructural characterization, and mechanical properties testing at both quasistatic and elevated strain rates

  8. Computer simulations for thorium doped tungsten crystals

    Energy Technology Data Exchange (ETDEWEB)

    Eberhard, Bernd

    2009-07-17

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO{sub 2}, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a

  9. Computer simulations for thorium doped tungsten crystals

    International Nuclear Information System (INIS)

    Tungsten has the highest melting point among all metals in the periodic table of elements. Furthermore, its equilibrium vapor pressure is by far the lowest at the temperature given. Thoria, ThO2, as a particle dopant, results in a high temperature creep resistant material. Moreover, thorium covered tungsten surfaces show a drastically reduced electronic work function. This results in a tremendous reduction of tip temperatures of cathodes in discharge lamps, and, therefore, in dramatically reduced tungsten vapor pressures. Thorium sublimates at temperatures below those of a typical operating cathode. For proper operation, a diffusional flow of thorium atoms towards the surface has to be maintained. This atomic flux responds very sensitively on the local microstructure, as grain boundaries as well as dislocation cores offer ''short circuit paths'' for thorium atoms. In this work, we address some open issues of thoriated tungsten. A molecular dynamics scheme (MD) is used to derive static as well as dynamic material properties which have their common origin in the atomistic behavior of tungsten and thorium atoms. The interatomic interactions between thorium and tungsten atoms are described within the embedded atom model (EAM). So far, in literature no W-Th interaction potentials on this basis are described. As there is no alloying system known between thorium and tungsten, we have determined material data for the fitting of these potentials using ab-initio methods. This is accomplished using the full potential augmented plane wave method (FLAPW), to get hypothetical, i.e. not occurring in nature, ''alloy'' data of W-Th. In order to circumvent the limitations of classical (NVE) MD schemes, we eventually couple our model systems to external heat baths or volume reservoirs (NVT, NPT). For the NPT ensemble, we implemented a generalization of the variable cell method in combination with the Langevin piston, which results in a set of Langevin equations, i.e. stochastic

  10. Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.

    Science.gov (United States)

    Braida, Washington; Christodoulatos, Christos; Ogundipe, Adebayo; Dermatas, Dimitris; O'Connor, Gregory

    2007-11-19

    Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu. PMID:17686582

  11. Strangers in a strange land: Egyptians in southern Palestine during the Bronze Age

    Directory of Open Access Journals (Sweden)

    Rachael Sparks

    2002-10-01

    Full Text Available When the Institute of Archaeology was formally established in 1937, it became responsible for housing Sir Flinders Petrie’s collection of archaeological material from Palestine. This unique inheritance has great value as a research collection, as its curator demonstrates here in her discussion of interaction between Egypt and Palestine in the Bronze Age.

  12. La médaille de bronze du CNRS à un physicien clermontois

    CERN Multimedia

    2005-01-01

    Evey year, the National center for scientific research (CNRS), rewards around fifty of searchers at various stages of their career. The bronze medal rewards the first work of a searcher, making of him a specialist in his field; Philippe Crochet was awarded this medal

  13. Celestial Symbolism in Central European Later Prehistory - Case Studies from the Bronze Age Carpathian Basin

    Science.gov (United States)

    Pásztor, Emília

    It is commonly held that the sun played a particularly important cultural role in later prehistoric Europe. The rise of a general European sun cult has even been suggested for the Bronze Age. During this period, the increasing use of special symbols assumed to represent the sun is easily discernible on different types of archaeological finds.

  14. Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies EHOMO and ELUMO and HOMO–LUMO energy gap were used for correlation with the corrosion data

  15. Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Rotaru, Ileana [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Varvara, Simona, E-mail: svarvara@uab.ro [Department of Exact Sciences and Engineering, “1 Decembrie 1918” University, 11-13 Nicolae Iorga St., 510009 Alba Iulia (Romania); Gaina, Luiza [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Muresan, Liana Maria, E-mail: limur@chem.ubbcluj.ro [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania)

    2014-12-01

    Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies E{sub HOMO} and E{sub LUMO} and HOMO–LUMO energy gap were used for correlation with the corrosion data.

  16. Protection of bronze artefacts through polymeric coatings based on nanocarriers filled with corrosion inhibitors

    Science.gov (United States)

    de Luna, Martina Salzano; Buonocore, Giovanna; Di Carlo, Gabriella; Giuliani, Chiara; Ingo, Gabriel M.; Lavorgna, Marino

    2016-05-01

    Protective coatings based on polymers synthesized from renewable sources (chitosan or an amorphous vinyl alcohol based polymer) have been prepared for the protection of bronze artifacts from corrosion. Besides acting as an effective barrier against corrosive species present in the environment, the efficiency of the coatings has been improved by adding corrosion inhibitor compounds (benzotriazole or mercaptobenzothiazole) to the formulations. The liquid medium of the formulations has been carefully selected looking at maximizing the wettability on the bronze substrate and optimizing the solvent evaporation rate. The minimum amount of inhibitor compounds has been optimized by performing accelerated corrosion tests on coated bronze substrates. The inhibitors have been directly dissolved in the coating-forming solutions and/or introduced by means of nanocarriers, which allow to control the release kinetics. The free dissolved inhibitor molecules immediately provide a sufficient protection against corrosion. On the other hand, the inhibitor molecules contained in the nanocarriers serve as long-term reservoir, which can be activated by external corrosion-related stimuli in case of particularly severe conditions. Particular attention has been paid to other features which affect the coating performances. Specifically, the adhesion of the protective polymer layer to the bronze substrate has been assessed, as well as its permeability properties and transparency, the latter being a fundamental feature of protective coating for cultural heritages. Finally, the protective efficiency of the produced smart coatings has been assessed through accelerated corrosion tests.

  17. The Agro Pontino region, refuge after the Early Bronze Age Avellino eruption of Mount Vesuvius, Italy?

    NARCIS (Netherlands)

    C. Bakels; J. Sevink; W. Kuijper; H. Kamermans

    2015-01-01

    In recent years it was discovered that the Middle to Late Holocene infi ll of the Agro Pontino graben (Central Italy) held a tephra layer originating from the Avellino eruption of the Vesuvius volcano. The eruption is dated to 1995 ± 10 calBC and took therefore place during the Early Bronze Age. Thi

  18. Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

    Science.gov (United States)

    Masi, G.; Chiavari, C.; Avila, J.; Esvan, J.; Raffo, S.; Bignozzi, M. C.; Asensio, M. C.; Robbiola, L.; Martini, C.

    2016-03-01

    Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au-Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (XPS). We have found a net surface enrichment in Zn and Sn after fire-gilding and presence of metallic Hg, Pb and Cu within the Au layer. Moreover, the composition distribution of the elements together with their oxidation has been determined. It was also revealed that metallic phases including Hg and Pb remain in the gilding after corrosion. Moreover, selective dissolution of Zn and Cu occurs in the crater due to galvanic coupling, which locally induces relative Sn species enrichment (decuprification). The feasibility advantages and disadvantages of chemical imaging using HR-SRPES to study artworks have been investigated on representative replicas.

  19. The study of bronze statuettes with the help of neutron-imaging techniques

    NARCIS (Netherlands)

    Van Langh, R.; Lehmann, E.; Hartmann, S.; Kaestner, A.; Scholten, F.

    2009-01-01

    Until recently fabrication techniques of Renaissance bronzes have been studied only with the naked eye, microscopically, videoscopically and with X-radiography. These techniques provide information on production techniques, yet much important detail remains unclear. As part of an interdisciplinary s

  20. Electrodeposition and corrosion resistance of nanocrystalline white bronze (CuSn) coatings

    NARCIS (Netherlands)

    Hovestad, A.; Lekka, M.; Willemsen, R.M.R.; Tacken, R.A.; Bonora, P.L.

    2008-01-01

    For jewellery applications electroplated white bronze (CuSn) was investigated as undercoating for noble metal finishes as alternative to nickel. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. An electrochemical study o

  1. Isotopic dietary reconstruction of humans from Middle Bronze Age Lerna, Argolid, Greece

    NARCIS (Netherlands)

    Triantaphyllou, S.; Richards, M. P.; Zerner, C.; Voutsaki, S.

    2008-01-01

    This study presents the results of a carbon and nitrogen stable isotope analysis of 39 human bone and 8 animal samples from Middle Bronze Age (or Middle Helladic, MH, ca. 2100-1700 BC) Lerna, Greece. The isotopic data indicate that the humans had a C-3 terrestrial diet while certain individuals appe

  2. Dating Archaeological Copper/Bronze Artifacts by Using the Voltammetry of Microparticles

    OpenAIRE

    Doménech-Carbó, Antonio; Doménech-Carbó, Maria Teresa; Capelo, Sofia; Pasíes, Trinidad; Martínez-Lázaro, Isabel

    2014-01-01

    A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.

  3. Cold Spraying of Cu-Al-Bronze for Cavitation Protection in Marine Environments

    Science.gov (United States)

    Krebs, S.; Gärtner, F.; Klassen, T.

    2015-01-01

    Traveling at high speeds, ships have to face the problem of rudder cavitation-erosion. At present, the problem is countered by fluid dynamically optimized rudders, synthetic, and weld-cladded coatings on steel basis. Nevertheless, docking and repair is required after certain intervals. Bulk Cu-Al-bronzes are in use at ships propellers to withstand corrosion and cavitation. Deposited as coatings with bulk-like properties, such bronzes could also enhance rudder life times. The present study investigates the coating formation by cold spraying CuAl10Fe5Ni5 bronze powders. By calculations of the impact conditions, the range of optimum spray parameters was preselected in terms of the coating quality parameter η on steel substrates with different temperatures. As-atomized and annealed powders were compared to optimize cavitation resistance of the coatings. Results provide insights about the interplay between the mechanical properties of powder and substrate for coating formation. Single particle impact morphologies visualize the deformation behavior. Coating performance was assessed by analyzing microstructures, bond strength, and cavitation resistance. These first results demonstrate that cold-sprayed bronze coatings have a high potential for ensuring a good performances in rudder protection. With further optimization, such coatings could evolve towards a competitive alternative to existing anti-cavitation procedures.

  4. Microstructure and properties of liquid-phase sintered tungsten heavy alloys by using ultra-fine tungsten powders

    Institute of Scientific and Technical Information of China (English)

    于洋; 王尔德

    2004-01-01

    The microstructure and properties of liquid-phase sintered 93W-4.9Ni-2.1Fe tungsten heavy alloys using ultra-fine tungsten powders (medium particle size of 700 nm) and original tungsten powders (medium particle size of 3 μm) were investigated respectively. Commercial tungsten powders (original tungsten powders) were mechanically milled in a high-energy attritor mill for 35 h. Ultra-fine tungsten powders and commercial Ni, Fe powders were consolidated into green compacts by using CIP method and liquid-phase sintering at 1 465 ℃ for 30 min in the dissociated ammonia atmosphere. Liquid-phase sintered tungsten heavy alloys using ultra-fine tungsten powders exhibit full densification (above 99% in relative density) and higher strength and elongation compared with conventional liquidphase sintered alloys using original tungsten powders due to lower sintering temperature at 1 465 ℃ and short sintering time. The mechanical properties of sintered tungsten heavy alloy are found to be mainly dependent on the particles size of raw tungsten powders and liquid-phase sintering temperature.

  5. Randomised controlled trials of staged teaching for basic life support. 1. Skill acquisition at bronze stage.

    Science.gov (United States)

    Assar, D; Chamberlain, D; Colquhoun, M; Donnelly, P; Handley, A J; Leaves, S; Kern, K B

    2000-06-01

    We have investigated a method of teaching community CPR in three stages instead of in a single session. These have been designated bronze, silver, and gold stages. The first involves only opening of the airway and chest compression with back blows for choking, the second adds ventilation in a ratio of compressions to breaths of 50:5, and the third is a conversion to conventional CPR. In a controlled randomised trial of 495 trainees we compared the performance in tests immediately after instruction of those who had received a conventional course and those who had had the simpler bronze level tuition. The tests were based on video recordings of simulated resuscitation scenarios and the readouts from recording manikins. Differences occurred as a direct consequence of ventilation being required in one group and not the other, some variation probably followed from unforeseen minor changes in the way that instruction was given, whilst others may have followed from the greater simplicity in the new method of training. A careful approach was followed by slightly more trainees in the conventional group whilst appreciably more in the bronze group remembered to shout for help (44% vs. 71%). A clear advantage was also seen for bronze level training in terms of those who opened the airway as taught (35% vs. 56%), for checking breathing (66% vs. 88%), and for mentioning the need to phone for an ambulance (21% vs. 32%). Little difference was observed in correct or acceptable hand position between the conventional group who were given detailed guidance and the bronze group who were instructed only to push on the centre of the chest. The biggest differences related to the number of compressions given. The mean delay to first compression was 63 s and 34 s, and the mean duration of pauses between compressions was 16 s and 9 s, respectively. Average performed rates were similar in the two groups, but more in the conventional group compressed too slowly whereas more in the bronze group

  6. Grain refinement of bronze alloy by equal-channel angular pressing (ECAP and its effect on corrosion behaviour

    Directory of Open Access Journals (Sweden)

    M.M. Sadawy

    2016-08-01

    Full Text Available The corrosion behaviour of bronze alloy prepared by equal channel angular pressing (ECAP was investigated in 3.5 wt. % NaCl solution. Immersion corrosion tests and different electrochemical techniques were carried out. The results showed that ECAPed bronze samples exhibited higher corrosion resistance compared with the as-cast alloy and the passive current density decreased with increasing number of passes. Moreover, the morphology of alloys indicated that the corrosion damage on the surface of ECAPed bronze was smooth and uniform while the as-cast alloy suffered from selective corrosion.

  7. Nanocomposite anode materials for sodium-ion batteries

    Science.gov (United States)

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  8. Hardening of self ion implanted tungsten and tungsten 5-wt% rhenium

    International Nuclear Information System (INIS)

    Highlights: ► W+ ion implantation was used to simulate neutron damage in W and W–5 wt%Re. ► A Hardness increase in pure tungsten was seen to saturate by 0.4 dpa. ► TEM of pure W shows little change in damage levels between 0.4 and 33 dpa. ► W–5 wt%Re alloy shows a hardness saturation between 0.07 dpa and 1.2 dpa. ► Above 13 dpa rhenium clusters are seen by APT and hardness rapidly increases. - Abstract: Tungsten is one of the most promising materials for high temperature components in any future nuclear fusion tokamak. In this study tungsten-ion implantation has been used to simulate the damage caused by neutrons in pure tungsten and tungsten 5 wt% rhenium. This damaged layer is only 300 nm deep so conventional mechanical tests cannot be used to investigate it. Nanoindentation has been used to measure the change in hardness as a function of six damage levels (0 dpa, 0.07 dpa, 0.4 dpa, 1.2 dpa, 13 dpa and 33 dpa). In pure tungsten the hardness increase is seen to saturate by 0.4 dpa at ≈0.8 GPa. Transmission electron microscopy of the damage structure sees a similar saturation of the loop volume number density at the same damage level. In the tungsten 5 wt% rhenium the increase in hardness is constant between 0.07 and 1.2 dpa, ≈0.85 GPa. The loop volume number density as measured using TEM is also shows little change in this region. At a damage level of 33 dpa the hardness increase is 2.88 GPa; this corresponds with the formation of small 3–5 nm rhenium clusters as observed using atom probe tomography.

  9. Selection of the temperature of casting the bronzes to plaster moulds

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2009-07-01

    Full Text Available The results of the investigations of the process of solidification of the bronze CuSn5Zn5Pb5-C (B555 and CuSn10-C (B10 in the hot plaster mould show in the work. For four temperatures of casting: 1200 ° C, 1180 ° C, 1160 ° C and 1140 ° C was conducted the investi-gation: the size of contraction cavity, the fulfillment of the mould cavity formative the casts of test slats about the thickness: 4 mm, 0,8 mm and 0,5 mm. It was conducted the investigation the processes sets in the arrangement the cast-mould and X-ray analysis phase XRD of compound coming into being in indirect layer created among mould and cast in the result of the thermal decomposition of the anhy-drite. It results that the temperature 1140 ° C is the optimum temperature of casting the bronze to hot plaster mould from carried out investiga-tions. The minimum thickness of the wall of the cast from the bronze B555 is 0.5 mm, and from the bronze B10 0.8 mm.The realization of casts about thinner walls is made difficult because of giving off formed gases in the result of the thermal decomposition of the anhydrite. The products of the decomposition of the anhydrite react with elements steps in the chemical composition of studied bronzes, create in the arrangement the cast-mould the indirect layer folded from: sulphites, sulphides, oxides and clean metals (Pb or their compounds, especially Sn and Sb.

  10. The textural properties and microstructure of konjac glucomannan - tungsten gels induced by DC electric fields.

    Science.gov (United States)

    Wang, Lixia; Zhuang, Yuanhong; Li, Jingliang; Pang, Jie; Liu, Xiangyang

    2016-12-01

    Konjac glucomannan - tungsten (KGM-T) gels were successfully prepared under DC electric fields, in the presence of sodium tungstate. The textural properties and microstructure of the gels were investigated by Texture Analyzer, Rheometer and SEM. Based on the response surface methodology (RSM) results, the optimum conditions for KGM-T gel springiness is 0.32% sodium tungstate concentration, 0.54% KGM concentration, 24.66V voltage and 12.37min treatment time. Under these conditions, the maximum springiness value of KGM-T gel is 1.21mm. Steady flow measurement indicated that KGM-T gel showed characteristic non-Newtonian pseudoplastic behaviour, with low flow behaviour indexes in the shear thinning region. SEM demonstrated the porosity of the freeze-dried samples. These findings may pave the way to use DC electric fields for the design and development of KGM gels and to apply KGM gels for practical applications.

  11. Formation of nanoscale tungsten oxide structures and colouration characteristics

    Indian Academy of Sciences (India)

    Vijay Bhooshan Kumar; Dambarudhar Mohanta

    2011-06-01

    In this work, pH dependent evolution of tungsten oxide (WO3) nanostructures is being reported along with physical characteristics. The synthesis was carried out via an inexpensive solvothermal cum chemical reduction route, with sodium tungstate (Na2WO4) and cetyl trimethyl ammonium bromide (C19H42NBr) as main reactants. The X-ray diffraction, together with transmission electron microscopic studies have revealed formation of regular polyhedral nanocrystalline structures and fractals as one goes from higher pH (= 5.5) to lower pH (= 2) values. The average crystallite size, as calculated throughWilliamson–Hall plots, was varied within 2.8–6.8 nm for different pH samples. Fourier transform infrared spectroscopy reveals in-plane bending vibration (W–OH), observable at ∼1630 cm-1 and strong stretching (W–O–W) located at ∼814 cm-1. Raman spectroscopy has divulged WO3 Raman active optical phonon modes positioned at ∼717 and 805 cm-1. The thermochromic and photochromic properties of the nanoscale WO3 sample prepared at pH = 5.5, are also highlighted.

  12. Dynamic behavior of novel tungsten penetrator materials

    International Nuclear Information System (INIS)

    The scope of the investigations was to find criteria which are related to the terminal ballistic performance of high strength tungsten KE-penetrator materials. The study comprised three tungsten alloys having densities above 17.1 g/cm3 and comparable static material strengths. For this purpose the authors investigated the dynamic material behavior by means of the instrumented Taylor-test. The influence of the strain rate on the yield strength and the maximum strain when cracking occurred were determined. The measured dynamic strength data were compared with the terminal ballistic efficiency of rods penetrating a semi-infinite RHA-target. Furthermore, the structural properties of the alloys were discussed with respect to their behavior in the regime of hydrodynamic flow

  13. Femtosecond fiber laser additive manufacturing of tungsten

    Science.gov (United States)

    Bai, Shuang; Liu, Jian; Yang, Pei; Zhai, Meiyu; Huang, Huan; Yang, Lih-Mei

    2016-04-01

    Additive manufacturing (AM) is promising to produce complex shaped components, including metals and alloys, to meet requirements from different industries such as aerospace, defense and biomedicines. Current laser AM uses CW lasers and very few publications have been reported for using pulsed lasers (esp. ultrafast lasers). In this paper, additive manufacturing of Tungsten materials is investigated by using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. Fully dense Tungsten part with refined grain and increased hardness was obtained and compared with parts made with different pulse widths and CW laser. The results are evidenced that the fs laser based AM provides more dimensions to modify mechanical properties with controlled heating, rapid melting and cooling rates compared with a CW or long pulsed laser. This can greatly benefit to the make of complicated structures and materials that could not be achieved before.

  14. Thermal stability of warm-rolled tungsten

    DEFF Research Database (Denmark)

    Alfonso Lopez, Angel

    and recrystallization occur in tungsten, and quantifying the kinetics and microstructuralaspects of these restoration processes. Two warm-rolled tungsten plates are annealed attemperatures between 1100 °C and 1350 °C, under vacuum conditions or argon atmosphere. Theeffects of annealing on the microstructure....... In the presentwork, the annealing behavior is investigated after introducing different deformation structures byrolling to moderate (67% thickness reduction) and high (90% thickness reduction) rollingreductions. The deformation-induced microstructures after rolling are characterized by theaforementioned techniques...... to assess the effect of the processing parameters. Characterization of theannealed state reveals the effect of the degree of deformation on the recovery and recrystallizationannealing phenomena. This allowed comparing recrystallization kinetics (in terms of nucleation andgrowth) in dependence on initial...

  15. Microstructural evolution of tungsten oxide thin films

    Science.gov (United States)

    Hembram, K. P. S. S.; Thomas, Rajesh; Rao, G. Mohan

    2009-10-01

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 °C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a "instability wheel" model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  16. Microstructural evolution of tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hembram, K.P.S.S., E-mail: hembram@isu.iisc.ernet.in [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India); Theoretical Science Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore - 560064 (India); Thomas, Rajesh; Rao, G. Mohan [Department of Instrumentation, Indian Institute of Science, Bangalore - 560 012 (India)

    2009-10-30

    Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, the films annealed above 400 deg. were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a 'instability wheel' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

  17. Synthesis of molybdenum and tungsten oxytetrafluorides

    Energy Technology Data Exchange (ETDEWEB)

    Butskij, V.D.; Ignatov, M.E.; Golovanov, B.V. (AN SSSR, Moscow. Inst. Obshchej i Neorganicheskoj Khimii)

    1985-03-01

    A simple method of preparating molybdenum and tungsten oxytetrafluorides by silicon dioxide interaction with hexafluoride of the corresponding metal in a glass at 120-150 deg C and MF/sub 6/ pressure of 0.4-0.5 atm, is developed. MOF/sub 4/ (M=Mo, W) yield is 94-95%, purity is 99%. Synthesized MOF/sub 4/ are characterized by the data of chemical analysis, IR and NMR/sup 19/F spectrometry.

  18. Synthesis of molybdenum and tungsten oxytetrafluorides

    International Nuclear Information System (INIS)

    A simple method of preparating molybdenum and tungsten oxytetrafluorides by silicon dioxide interaction with hexafluoride of the corresponding metal in a glass at 120-150 deg C and MF6 pressure of 0.4-0.5 atm, is developed. MOF4 (M=Mo, W) yield is 94-95%, purity is 99%. Synthesized MOF4 are characterized by the data of chemical analysis, IR and NMR19F spectrometry

  19. Preliminary Study of Corrosion Status on Bronzes Excavated from Qin Dynasty Tombs at Xinfeng Town in China

    Directory of Open Access Journals (Sweden)

    Qian-li Fu

    2012-01-01

    Full Text Available From 2007 to 2008, many bronze wares of Qin Dynasty were excavated from tombs at Xinfeng town. Being an important finding, these bronze wares attracted people’s attention, especially for their conservation. Therefore, the corrosive products were explored by using Scanning Electron Microscope with Energy Dispersive X-ray Detector (SEM/EDS, X-Ray diffraction (XRD, and Raman spectroscopy (RM, which provided much valuable information on the conservation of these bronze wares. According to tested results, the corrosive products of bronzes were found to be comprised of cuprite (Cu2O, covellite (CuS, lead carbonate (PbCO3, and malachite (CuCO3·Cu(OH2. Meantime, the multilayer corrosive structure was found in some samples due to the cracks in Cu2O layer which had formed many microchannels to promote the material migration.

  20. Controlled nanostructuration of polycrystalline tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    Girault, B. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Institut de Recherche en Genie Civil et Mecanique (UMR CNRS 6183), LUNAM Universite, Universite de Nantes, Centrale Nantes, CRTT, 37 Bd de l' Universite, BP 406, 44602 Saint-Nazaire Cedex (France); Eyidi, D.; Goudeau, P.; Guerin, P.; Bourhis, E. Le; Renault, P.-O. [Institut P' (UPR 3346 CNRS), Universite de Poitiers, ENSMA, Bd Pierre et Marie Curie, 86962 Futuroscope Cedex (France); Sauvage, T. [CEMHTI/CNRS (UPR 3079 CNRS), Universite d' Orleans, 3A rue de la Ferollerie, 45071 Orleans Cedex 2 (France)

    2013-05-07

    Nanostructured tungsten thin films have been obtained by ion beam sputtering technique stopping periodically the growing. The total thickness was maintained constant while nanostructure control was obtained using different stopping periods in order to induce film stratification. The effect of tungsten sublayers' thicknesses on film composition, residual stresses, and crystalline texture evolution has been established. Our study reveals that tungsten crystallizes in both stable {alpha}- and metastable {beta}-phases and that volume proportions evolve with deposited sublayers' thicknesses. {alpha}-W phase shows original fiber texture development with two major preferential crystallographic orientations, namely, {alpha}-W<110> and unexpectedly {alpha}-W<111> texture components. The partial pressure of oxygen and presence of carbon have been identified as critical parameters for the growth of metastable {beta}-W phase. Moreover, the texture development of {alpha}-W phase with two texture components is shown to be the result of a competition between crystallographic planes energy minimization and crystallographic orientation channeling effect maximization. Controlled grain size can be achieved for the {alpha}-W phase structure over 3 nm stratification step. Below, the {beta}-W phase structure becomes predominant.

  1. The tungsten divertor experiment at ASDEX Upgrade

    Science.gov (United States)

    Neu, R.; Asmussen, K.; Krieger, K.; Thoma, A.; Bosch, H.-S.; Deschka, S.; Dux, R.; Engelhardt, W.; García-Rosales, C.; Gruber, O.; Herrmann, A.; Kallenbach, A.; Kaufmann, M.; Mertens, V.; Ryter, F.; Rohde, V.; Roth, J.; Sokoll, M.; Stäbler, A.; Suttrop, W.; Weinlich, M.; Zohm, H.; Alexander, M.; Becker, G.; Behler, K.; Behringer, K.; Behrisch, R.; Bergmann, A.; Bessenrodt-Weberpals, M.; Brambilla, M.; Brinkschulte, H.; Büchl, K.; Carlson, A.; Chodura, R.; Coster, D.; Cupido, L.; de Blank, H. J.; de Peña Hempel, S.; Drube, R.; Fahrbach, H.-U.; Feist, J.-H.; Feneberg, W.; Fiedler, S.; Franzen, P.; Fuchs, J. C.; Fußmann, G.; Gafert, J.; Gehre, O.; Gernhardt, J.; Haas, G.; Herppich, G.; Herrmann, W.; Hirsch, S.; Hoek, M.; Hoenen, F.; Hofmeister, F.; Hohenöcker, H.; Jacobi, D.; Junker, W.; Kardaun, O.; Kass, T.; Kollotzek, H.; Köppendörfer, W.; Kurzan, B.; Lackner, K.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L. L.; Leuterer, F.; Manso, M. E.; Maraschek, M.; Mast, K.-F.; McCarthy, P.; Meisel, D.; Merkel, R.; Müller, H. W.; Münich, M.; Murmann, H.; Napiontek, B.; Neu, G.; Neuhauser, J.; Niethammer, M.; Noterdaeme, J.-M.; Pasch, E.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pitcher, C. S.; Poschenrieder, W.; Raupp, G.; Reinmüller, K.; Riedl, R.; Röhr, H.; Salzmann, H.; Sandmann, W.; Schilling, H.-B.; Schlögl, D.; Schneider, H.; Schneider, R.; Schneider, W.; Schramm, G.; Schweinzer, J.; Scott, B. D.; Seidel, U.; Serra, F.; Speth, E.; Silva, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ulrich, M.; Varela, P.; Verbeek, H.; Verplancke, Ph; Vollmer, O.; Wedler, H.; Wenzel, U.; Wesner, F.; Wolf, R.; Wunderlich, R.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.

    1996-12-01

    Tungsten-coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of the ASDEX Upgrade tokamak and cover almost 90% of the surface facing the plasma in the strike zone. Over 600 plasma discharges have been performed to date, around 300 of which were auxiliary heated with heating powers up to 10 MW. The production of tungsten in the divertor was monitored by a W I line at 400.8 nm. In the plasma centre an array of spectral lines at 5 nm emitted by ionization states around W XXX was measured. From the intensity of these lines the W content was derived. Under normal discharge conditions W-concentrations around 0741-3335/38/12A/013/img12 or even lower were found. The influence on the main plasma parameters was found to be negligible. The maximum concentrations observed decrease with increasing heating power. In several low power discharges accumulation of tungsten occurred and the temperature profile was flattened. The concentrations of the intrinsic impurities carbon and oxygen were comparable to the discharges with the graphite divertor. Furthermore, the density and the 0741-3335/38/12A/013/img13 limits remained unchanged and no negative influence on the energy confinement or on the H-mode threshold was found. Discharges with neon radiative cooling showed the same behaviour as in the graphite divertor case.

  2. Epitaxial growth of tungsten nanoparticles on alumina and spinel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Suarez, T; Lopez-Esteban, S; Pecharroman, C; Esteban-Cubillo, A; Moya, J S [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), C/ Sor Juana Ines de la Cruz 3, 28049, Cantoblanco, Madrid (Spain); Diaz, L A; Torrecillas, R [Nanomaterials and Nanotechnology Research Center (CINN), Consejo Superior de Investigaciones CientIficas (CSIC), C/ Francisco Pintado Fe 26, 33011, Oviedo, Asturias (Spain); Gremillard, L [Universite de Lyon, INSA-Lyon, MATEIS, UMR CNRS 5510, 20 avenue Albert Einstein, Villeurbanne F-69621 (France)], E-mail: jsmoya@icmm.csic.es

    2008-05-28

    Isolated tungsten nanoparticles ({alpha}-W and {beta}-W phase) were synthesized and epitaxially grown on alumina and spinel particle surfaces with an average tungsten size of {<=}20 nm for a low tungsten content (of {<=}1.5 vol%). Using tungsten (VI) ethoxide alcoholic solutions, tungsten trioxide hydrated precursors were attached to a ceramic grains surface as a nanoparticle coating. High-resolution transmission electron microscopy (HRTEM) micrographs showed epitaxial interfaces between alumina, spinel and metallic tungsten. This epitaxial growth is assumed to be due to the effect of water vapour on the sublimation of ortho-tungstic acid during the reduction process in a hydrogen atmosphere. The planes involved in the epitaxy were found to be (22-bar 0){sub Al2O3} parallel (121){sub W} and (311){sub MgAl2O4} parallel (110){sub W}.

  3. Process for separation of tungsten and molybdenum by extraction

    International Nuclear Information System (INIS)

    A process for the separation of tungsten and molybdenum by extraction involves the addition of HCl or HNO3 to an aqueous solution containing tungsten and molybdenum to obtain a pH from 0.5 to 4.3, and introduction of a stabilizer comprising water-soluble phosphorus salts and a complexing agent, hydrogen peroxide, in an amount from 1.5 to 2 mole per 1 g-atom of the total content of tungsten and molybdenum. Then molybdenum is selectively extracted from the resulting aqueous solution with tri-n-butylphosphate with equal volumetric proportioning of the aqueous and organic solutions. Re-extraction of molybdenum and partially tungsten is carried out from the organic extracting agent with an alkali or soda solution. The process makes possible the preparation of tungsten solution containing no more than 0.001 g/l of molybdenum, and an increase in the degree of extraction of tungsten and molybdenum

  4. Measurement of thermophysical property of plasma forming tungsten nanofiber layer

    Science.gov (United States)

    Kajita, Shin; Yagi, Takashi; Kobayashi, Kenichi; Tokitani, Masayuki; Ohno, Noriyasu

    2016-05-01

    Thermophysical property of a nanostructured tungsten layer formed on a tungsten film was investigated. A 1-µm-thick tungsten film deposited on a quartz glass substrate was irradiated with a high density helium plasma at the surface temperature of 1500 K. The plasma irradiation led to the formation of highly porous fiberform-nanostructured tungsten layer with a thickness of 3.5 µm. Impulse heating was applied at the interface of the film/substrate, and transient heat diffusion was observed using a pulsed light heating thermoreflectance apparatus. The thermoreflectance signals clearly differed between the nanostructure existing and mechanically removed regions; the difference can be attributed to thermal effusivity of the nanostructured tungsten layer. The estimated thermal conductivity of the nanostructured tungsten decreases to ∼2% of that of bulk when the density of the nanostructure is assumed to be ∼6% of the bulk value.

  5. Synthesis and electrical characterization of tungsten oxide nanowires

    Institute of Scientific and Technical Information of China (English)

    Huang Rui; Zhu Jing; Yu Rong

    2009-01-01

    Tungsten oxide nanowires of diameters ranging from 7 to 200 nm are prepared on a tungsten rod substrate by using the chemical vapour deposition (CVD) method with vapour-solid (VS) mechanism. Tin powders are used to control oxygen concentration in the furnace, thereby assisting the growth of the tungsten oxide nanowires. The grown tungsten oxide nanowires are determined to be of crystalline W18O49. Ⅰ-Ⅴ curves are measured by an in situ transmission electron microscope (TEM) to investigate the electrical properties of the nanowires. All of the Ⅰ-Ⅴ curves observed are symmetric, which reveals that the tungsten oxide nanowires are semiconducting. Quantitative analyses of the experimental I V curves by using a metal-semiconductor-metal (MSM) model give some intrinsic parameters of the tungsten oxide nanowires, such as the carrier concentration, the carrier mobility and the conductivity.

  6. Chemical vapour deposition of tungsten and tungsten silicide layers for applications in novel silicon technology

    CERN Document Server

    Li, F X

    2002-01-01

    This work was a detailed investigation into the Chemical Vapour Deposition (CVD) of tungsten and tungsten silicide for potential applications in integrated circuit (IC) and other microelectronic devices. These materials may find novel applications in contact schemes for transistors in advanced ICs, buried high conductivity layers in novel Silicon-On-Insulator (SOI) technology and in power electronic devices. The CVD techniques developed may also be used for metal coating of recessed or enclosed features which may occur in novel electronic or electromechanical devices. CVD of tungsten was investigated using the silicon reduction reaction of WF sub 6. W layers with an optimum self-limiting thickness of 100 nm and resistivity 20 mu OMEGA centre dot cm were produced self-aligned to silicon. A hydrogen passivation technique was developed as part of the wafer pre-clean schedule and proved essential in achieving optimum layer thickness. Layers produced by this approach are ideal for intimate contact to shallow junct...

  7. Separation and estimation of tungsten and copper in tungsten-copper alloy

    International Nuclear Information System (INIS)

    The tungsten-copper alloy, also called as collet material, is regularly used in resistance welding of end caps of nuclear fuel pins during their fabrication at Nuclear Fuel Complex (NFC). The desirable properties of this material for welding purpose varies with the composition of the alloy. Therefore, it is mandatory to know its composition prior to its application. The present paper describes a modified gravimetric method where tungsten is separated from copper by digestion of the sample in concentrated nitric acid followed by filtration and subsequent ignition of the residue to tungstic oxide (WO3) while copper in the filtrate is estimated by electro-gravimetric method. A co-efficient of variation (CV) of ± 0.2% for tungsten and ± 0.4% for copper have been achieved. (author)

  8. Grain refinement of bronze alloy by equal-channel angular pressing (ECAP) and its effect on corrosion behaviour

    OpenAIRE

    M.M. Sadawy; Ghanem, M

    2016-01-01

    The corrosion behaviour of bronze alloy prepared by equal channel angular pressing (ECAP) was investigated in 3.5 wt. % NaCl solution. Immersion corrosion tests and different electrochemical techniques were carried out. The results showed that ECAPed bronze samples exhibited higher corrosion resistance compared with the as-cast alloy and the passive current density decreased with increasing number of passes. Moreover, the morphology of alloys indicated that the corrosion damage on the surface...

  9. Characterisation of passive layers of bronze patinas (Cu-Sn alloys) in relation with the tin content of the alloy

    OpenAIRE

    Robbiola, Luc; Fiaud, C.; Harch, A.

    1993-01-01

    International audience In order to develop our knowledge of the relations between the high degree of protectiveness of passive layers and their composition, corroded archaeological bronzes of Bronze Age (1500-950 BC) have been characterised by different methods of analysis. Results reveal that the passive layers have a bilayer structure and are due to the selective dissolution of copper from the copper solid solution of the alloy to the electrolyte. For all of the objects, the ratio [(Sn/C...

  10. Low sodium level

    Science.gov (United States)

    Low sodium level is a condition in which the amount of sodium (salt) in the blood is lower than normal. ... Sodium is found mostly in the body fluids outside the cells. It is very important for maintaining ...

  11. Sodium and Food Sources

    Science.gov (United States)

    ... Disease Cholesterol High Blood Pressure Million Hearts® WISEWOMAN Sodium and Food Sources Recommend on Facebook Tweet Share ... food [PDF-867K] and how to reduce sodium. Sodium Reduction Is Challenging Types of food matter: More ...

  12. The Tungsten Demand and Supply Situation in Recent Years

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>Tungsten is an important and valuable resource listed by the State as a kind of special minerals under the State protection. By the end of 2005, China had 310 tungsten mining areas with the total tungsten deposit amounting to 5.69 million tons. Among the total deposit, wolframite accounts for approximately 20.8 per cent and scheelite accounts for about 70 per cent with

  13. Experimental setup for tungsten transport studies at the NSTX tokamak

    International Nuclear Information System (INIS)

    Tungsten particles have been introduced into the National Spherical Torus Experiment (NSTX) in Princeton with the purpose to investigate the effects of tungsten injection on subsequent plasma discharges. An experimental setup for the study of tungsten particle transport is described where the particles are introduced into the tokamak using a modified particle dropper, otherwise used for lithium-powder injection. An initial test employing a grazing-incidence extreme ultraviolet spectrometer demonstrates that the tungsten-transport setup could serve to infer particle transport from the edge to the hot central plasmas of NSTX.

  14. Recent advances in high density tungsten composite processing. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Cytron, S.

    1993-10-01

    Conventional liquid phase sintering has been the mainstay for processing tungsten alloy composites for the past several decades. New application demands being placed on these high density composites have resulted in the emergence of new processing approaches aimed at developing a new generation of high density tungsten composite materials. Recent investigative studies into rapid solidification technology, solid state sintering, mechanical alloying, and explosive compaction are reported here to highlight these recent processing trends. Tungsten heavy alloys, Tungsten alloy composite, Solid state sintering, Mechanical alloying, Explosive composition, Rapid solidification technology.

  15. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    Science.gov (United States)

    Hilsenbeck, Shane J.; McCarley, Robert E.; Schrader, Glenn L.; Xie, Xiaobing

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  16. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Energy Technology Data Exchange (ETDEWEB)

    Airapetov, A. A.; Begrambekov, L. B., E-mail: lbb@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Buzhinskiy, O. I. [State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation); Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2015-12-15

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400–1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  17. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Science.gov (United States)

    Airapetov, A. A.; Begrambekov, L. B.; Buzhinskiy, O. I.; Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A.

    2015-12-01

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400-1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  18. WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)

    DEFF Research Database (Denmark)

    Ahmadi, Majid; Sahoo, Satyaprakash; Younesi, Reza;

    2014-01-01

    Tungsten oxide (WO3) nano-ribbons (NRs) were obtained by annealing tungstite (WO3·H2O) NRs. The latter was synthesized below room temperature using a simple, environmentally benign, and low cost aging treatment of precursors made by adding hydrochloric acid to diluted sodium tungstate solutions (...

  19. Wet and dry accelerated aging tests in a spray chamber to understand the effects of acid rain frequencies on bronze corrosion

    OpenAIRE

    Gianni, Liliana; Cavallini, Mauro; Natali, Stefano; Adriaens, Annemie

    2013-01-01

    We have conducted controlled laboratory experiments using a series of bronze alloys exposed to frequent, repeated wet and dry cycles, to simulate frequent acid rain exposure and study the resultant corrosion processes in bronze artifacts exposed to an outdoor urban environment. To simulate rainwater and condensation, a spray chamber for the corrosion tests was assembled, which delivered homogeneous vapor diffusion and drop deposition. Three bi-component bronzes, with 3%, 7% and 20% tin conten...

  20. Marks of heliacal rising of Sirius on the sundial of the Bronze Age

    CERN Document Server

    Vodolazhskaya, Larisa N; Nevsky, Mikhail Yu

    2015-01-01

    The article presents the results of interdisciplinary research made with the help of archaeological, physical and astronomical methods. The aim of the study were analysis and interpretation corolla marks of the vessel of the Late Bronze Age, belonging to Srubna culture and which was found near the Staropetrovsky village in the northeast of the Donetsk region (Central Donbass). Performed calculations and measurements revealed that the marks on the corolla of Staropetrovsky vessel are marking of horizontal sundial with a sloping gnomon. Several marks on the corolla of the vessel have star shape. Astronomical calculations show that their position on the corolla, as on "dial" of watch, indicates the time of qualitative change the visibility of Sirius in the day its heliacal rising and the next few days in the Late Bronze Age at the latitude of detection of Staropetrovsky vessel. Published in the article the results of astronomical calculations allow to state that astronomical year in the Srubna tradition began wi...

  1. Chronology for the Aegean Late Bronze Age 1700-1400 B.C.

    Science.gov (United States)

    Manning, Sturt W; Ramsey, Christopher Bronk; Kutschera, Walter; Higham, Thomas; Kromer, Bernd; Steier, Peter; Wild, Eva M

    2006-04-28

    Radiocarbon (carbon-14) data from the Aegean Bronze Age 1700-1400 B.C. show that the Santorini (Thera) eruption must have occurred in the late 17th century B.C. By using carbon-14 dates from the surrounding region, cultural phases, and Bayesian statistical analysis, we established a chronology for the initial Aegean Late Bronze Age cultural phases (Late Minoan IA, IB, and II). This chronology contrasts with conventional archaeological dates and cultural synthesis: stretching out the Late Minoan IA, IB, and II phases by approximately 100 years and requiring reassessment of standard interpretations of associations between the Egyptian and Near Eastern historical dates and phases and those in the Aegean and Cyprus in the mid-second millennium B.C. PMID:16645092

  2. DIFFUSION COUPLE BETWEEN HIGH STRENGTH WEAR-RESISTING ALUMINUM BRONZE AND MACHINING TOOLS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Diffusion couples of tool materials (prepared from commercially available high speed steel and YW1 carbide tools) and the wear-resisting aluminum bronze (KK) were prepared by casting to study the diffusion pattern and phase formation sequence in order to clarify the diffusion wear of the tools during the turning of the wear-resisting aluminum bronze. Optical micrographs show that good contact was obtained at the tool material-KK interface. After annealed at 900 ℃ for 6 h, strong inter-diffusion across the interface was observed. Microprobe analysis was used to study the elemental distribution across the interface and X-ray diffractometry was used to study the phases formed at the interface.

  3. Biological affinities and adaptations of Bronze Age Bactrians: III. An initial craniometric assessment.

    Science.gov (United States)

    Hemphill, B E

    1998-07-01

    Discovery of a previously unknown Bronze Age civilization (Oxus Civilization) centered on the oases of Central Asia immediately raised questions concerning the origin and interregional impacts of this civilization. Fifteen craniometric variables from 12 Bronze Age samples--encompassing 544 adults from Central Asia, Iran, the Indus Valley, and Anatolia--are compared to test which, if any, of the current hypotheses offered by archaeologists are best supported by the pattern of phenetic affinities possessed by the Oxus Civilization inhabitants of the north Bactrian oasis. Craniometric differences between samples are compared with Mahalanobis generalized distance, and patterns of phenetic affinity are assessed with two types of cluster analysis (WPGMA, neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis indicate that current hypotheses for both the origin and interregional impacts of Oxus Civilization populations are incomplete. PMID:9696149

  4. Studies on bronze pre-monetary signs found in Dobroudja using XRF and micro-PIXE

    Science.gov (United States)

    Constantinescu, B.; Cristea-Stan, D.; Talmatchi, G.; Ceccato, D.

    2016-03-01

    We performed compositional analyses on 180 Scythian-type arrowheads and pre-monetary signs using XRF method and on 60 small fragments of such items (approx. 100 microns diameter), sampling being performed on previously corrosion-cleaned areas on their surface, using micro-PIXE. The items are found in Dobroudja, Istros-Histria region. The most relevant for numismatists result is that for each finding place the same type of alloy was used both for fighting arrowheads and for pre-monetary signs. Our analyses revealed three types of alloys: Cu-Sn-Pb ("normal" bronze), Cu-Sn-Mn-Pb and Cu-Sn-Sb-Pb. The presence of antimony suggests the use of fahlore-type poly-metals deposits, most probably from Caucasus Mountains. The problem of ancient bronze containing manganese is more complicated; an explanation could be the use of manganese oxides as flux necessary to smelt oxidized ores.

  5. Radiocarbon dating of ancient bronze statues: Preliminary results from the Riace statues

    Energy Technology Data Exchange (ETDEWEB)

    Calcagnile, L., E-mail: lucio.calcagnile@unile.i [CEDAD, Department of Innovation Engineering, University of Salento, Via per Monteroni, 73100 Lecce (Italy); D' Elia, M.; Quarta, G. [CEDAD, Department of Innovation Engineering, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Vidale, M. [Istituto Centrale per il Restauro, Piazza San Francesco di Paola, 9, 00184 Rome (Italy)

    2010-04-15

    The low amount of material needed for the measurements makes AMS radiocarbon a technique suitable for the dating of ancient bronze artefacts through the analysis of the organic residues contained into the casting cores. We present the results of the AMS radiocarbon dating analyses carried out on the organic remains extracted from the casting cores of the Riace bronzes, among the most famous and well preserved sculptures of the Greek-Classical period. Although different dating hypotheses have been suggested on the base of stylistic considerations, no conclusive answers are, so far, available. The sample selection and preparation protocols of the different kind of organic materials (charred wood, vegetal remains and animal hairs) are described as well as the interpretation of the results in the frame of the current dating hypotheses and available analytical information about the casting technology.

  6. Comparative modeling of Bronze Age land use in the Malatya Plain (Turkey)

    Science.gov (United States)

    Arıkan, Bülent; Restelli, Francesca Balossi; Masi, Alessia

    2016-03-01

    Computational modeling in archeology has proven to be a useful tool in quantifying changes in the paleoenvironment. This especially useful method combines data from diverse disciplines to answer questions focusing on the complex and non-linear aspects of human-environment interactions. The research presented here uses various proxy records to compare the changes in climate during the Bronze Age in the Malatya Plain in eastern Anatolia, which is situated at the northern extremity of northern Mesopotamia. Extensive agropastoral land use modeling was applied to three sites of different size and function in the Malatya Plain during the Early Bronze Age I period to simulate the varying scale and intensity of human impacts in relation to changes in the level of social organization, demography, and temporal length. The results suggest that even in land use types subjected to a light footprint, the scale and intensity of anthropogenic impacts change significantly in relation to the level of social organization.

  7. Connections: the relationships between Neolithic and Bronze Age Megalithic Astronomy in Britain

    CERN Document Server

    Higginbottom, Gail

    2015-01-01

    It has already been empirically verified that for many Bronze Age monuments erected in Scotland between 1400-900 BC, there was a concerted effort on behalf of the builders to align their monuments to astronomical bodies on the horizon. It has also been found that there are two common sets of complex landscape and astronomical patternings, combining specific horizon qualities, like distance and elevation, with the rising and setting points of particular astronomical phenomena. However, it has only been very recently demonstrated by us that that the visible astronomical-landscape variables found at Bronze Age sites on the inner isles and mainland of western Scotland were first established nearly two millennia earlier, with the erection of the mooted first standing-stone 'great circles' in Britain: Callanish and Stenness of Scotland (see G. Higginbottom and R. Clay, The Origins of Standing Stone Astronomy in Britain submitted to Journal of Archaeological Science & available on ArXiv). In the current paper we...

  8. Neolithic and Bronze Age migration to Ireland and establishment of the insular Atlantic genome.

    Science.gov (United States)

    Cassidy, Lara M; Martiniano, Rui; Murphy, Eileen M; Teasdale, Matthew D; Mallory, James; Hartwell, Barrie; Bradley, Daniel G

    2016-01-12

    The Neolithic and Bronze Age transitions were profound cultural shifts catalyzed in parts of Europe by migrations, first of early farmers from the Near East and then Bronze Age herders from the Pontic Steppe. However, a decades-long, unresolved controversy is whether population change or cultural adoption occurred at the Atlantic edge, within the British Isles. We address this issue by using the first whole genome data from prehistoric Irish individuals. A Neolithic woman (3343-3020 cal BC) from a megalithic burial (10.3× coverage) possessed a genome of predominantly Near Eastern origin. She had some hunter-gatherer ancestry but belonged to a population of large effective size, suggesting a substantial influx of early farmers to the island. Three Bronze Age individuals from Rathlin Island (2026-1534 cal BC), including one high coverage (10.5×) genome, showed substantial Steppe genetic heritage indicating that the European population upheavals of the third millennium manifested all of the way from southern Siberia to the western ocean. This turnover invites the possibility of accompanying introduction of Indo-European, perhaps early Celtic, language. Irish Bronze Age haplotypic similarity is strongest within modern Irish, Scottish, and Welsh populations, and several important genetic variants that today show maximal or very high frequencies in Ireland appear at this horizon. These include those coding for lactase persistence, blue eye color, Y chromosome R1b haplotypes, and the hemochromatosis C282Y allele; to our knowledge, the first detection of a known Mendelian disease variant in prehistory. These findings together suggest the establishment of central attributes of the Irish genome 4,000 y ago. PMID:26712024

  9. Computed Tomography and Computed Radiography of late Bronze Age Cremation Urns from Denmark

    DEFF Research Database (Denmark)

    Harvig, Lise Lock; Lynnerup, Niels; Amsgaard Ebsen, Jannie

    2012-01-01

    To improve methods used to study prehistoric cremation rituals, cremation urns from the Danish late Bronze Age were examined using Computed Tomography and Computed Radiography (Digital X-ray). During microexcavation, the digital images were used as registration tool. Our results suggest that oste...... intensity show markedly poorer preservation and recovery than white calcined fragments do. Thus post-excavation estimations of cremation intensity are systematically biased...

  10. The metallurgy in Romagna and surrounding area in the Bronze Age.

    Directory of Open Access Journals (Sweden)

    Marcello Ravaglia

    2009-10-01

    Full Text Available The outline of the metallurgical production in Romagna and western limit represented by the province of Bologna shows a solid activity during the entire Bronze Age. Despite the preliminary state of the research, through the collection of records and the distributive analysis, it is possible to evaluate some of the peculiarities of the region. In particular, the presence of hoards in EBA and FBA suggests the main focus for the analysis of exchange dynamics between Northern and Central Italy.

  11. Electrolytic surface hardening of steel,cast iron and aluminium-bronze

    Institute of Scientific and Technical Information of China (English)

    Suhas Keshav Paknikar

    2006-01-01

    Electrolytic hardening process was developed in USSR in the 1950s. The process was developed but was not commercially exploited. There is no evidence of work done on this process in India. The author has done this original work applied to different materials like steel,cast iron and aluminum-bronze. This paper gives details of microstructural transformations along with hardness value achieved. There is vital scope for this process to become viable for surface hardening and selective hardening of small components.

  12. On the Origin of Bronze Belt Plaques of Ancient Nomads in Northern China

    Institute of Scientific and Technical Information of China (English)

    WUEn; 丁小雷

    2003-01-01

    The bronze plaques decorated with animal, human or geometric designs were the ornaments on the leather belts of the nomadic people, such as Xiongnu (Hun) and Xianbei (Sienpi) in Northern China in the Qin and Han Dynasties. These plaques had unique regional and ethnical characteristics. There have been many different ideas on the origination of this kind of plaques. The author plans to give his own opinion hereby on this issue.

  13. Towards mineralogical and geochemical reference groups for some Bronze Age ceramics 
from Transylvania (Romania)

    OpenAIRE

    Volker Hoeck; Corina Ionescu; Lucretia Ghergari; Carmen Precup

    2009-01-01

    Based on their chemical composition ceramic shards from three Bronze Age sites in Transylvania, i.e., Copăceni, Derşida and Palatca respectively, were distinguished by major, trace, and RE elements. Within the Copăceni samples, two subgroups (A and B) showing different chemistry and mineralogy were additionally separated out. The link between chemistry and mineralogy showed clearly the important contribution of the temper to the overall chemistry of the ceramic shards. In turn, the chemistry ...

  14. 黑豆嘴类型青铜器中的西来因素%Western Elements in the Bronzes of Heidouzui Type

    Institute of Scientific and Technical Information of China (English)

    张文立; 林沄

    2004-01-01

    The cultural elements contained in the bronzes of Heidouzui type have often been studied in academic circles,but no unanimous views have been reached.The present paper discusses two forms of bronze ornaments of the Kayao culture in the Qinghai region and their date,as well as the relationship of some bronzes handed down from ancient times with those unearthed from Qinghai.On the basis of their comparative study the authors put forward that the Heidouzui-type bronzes contain cultural elements coming from the Qinghai region and even farther areas.These western elements might have been spread eastward and northward to still farther regions.

  15. Fabrication of tungsten and tungsten alloy and its high heat load testing for fusion applications

    International Nuclear Information System (INIS)

    Tungsten is one of the most promising candidate materials for an application as plasma facing material (PFM) in future thermonuclear fusion devices. In the divertor region PFM will be exposed to very severe heat load conditions. Steady state heat loads will be around 5 MW/m2 - 10 MW/m2 and in some parts of the divertor even 20 MW/m2 for short periods. These steady state heat loads are accompanied by transient events such as edge localised modes (ELMs), vertical displacement events (VDEs) and plasma disruptions which deposit very high heat loads of up to several MJ/m2 on the PFMs. Important properties which enable tungsten to withstand such environmental conditions are its high melting point, high thermal conductivity and low erosion rate. In present study, we have fabricated Pure Tungsten (W) and Tungsten +1wt. % La2O3 (WL) pallets of size 50 mm (dia) and 9 mm (height) through Powder Metallurgical process using graphite mould and sintered in Direct Sintering Press (DSP) at 2390 °C with 40 MPa pressing force. The crack formations and surface modification behaviours under transient high heat load condition were investigated. Detailed characterization of the exposed sample for its various properties evaluation will be discussed and presented in the paper

  16. Nordic and Celtic: religion in southern Scandinavia during the late bronze age and early iron age

    Directory of Open Access Journals (Sweden)

    Marianne Görman

    1990-01-01

    Full Text Available By means of modern archeological research it is today possible to gain much information even from non-written material, This paper covers the late bronze age and early iron age, ca. 1000 B.C. —O. It is based on material from Denmark, the Southwest of Sweden, and the Southeast of Norway. This region formed a cultural unity since the sea bound the area together. Our main sources of knowledge of Nordic religion during this time span are votive offerings and rock-carvings. During the bronze age and early iron age the Nordic peasant population had intensive contacts with the Southeastern and Centralparts of Europe. A great quantity of imported objects bear evidence of widespread connections. The inhabitants of the Nordic area not only brought home objects, but also ideas and religious conceptions. This is clearly reflected in the iconography. The cultures with which connections were upheld and from which ideas were introduced were those of Hallstatt and La Tène. They were both Celtic iron age cultures prospering in Central Europe at the same time as the late bronze age and early iron age in the Nordic area. This means that the new symbols in the Nordic area come from a Celtic environment. Consequently, Celtic religion such as it may be found in the pre-Roman period, can clarify the meaning of the conceptions, linked with these symbols.

  17. Effect of heat treatment on microstructure and properties of hot-extruded nickel-aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of heat treatment on the microstructure and properties of a hot-extruded nickel-aluminum bronze was investigated. Experimental materials were heat treated through different processes, including quenching, normalizing, aging and annealing, and their microstructure, corrosion resistance and mechanical properties were characterized. It is found that quenching causes all β phase transformed into β' phase, however, normalizing causes β phase transformed into β', α and κ phases. When the quenched sample is aged, fine κ phase is precipitated from the as-quenched microstructure of β' phase. Annealing causes the transformation of β' into a and κ phases. The results of mechanical property tests show that quenching, normalizing and aging improve the tensile strength and hardness of the experimental material, with a corresponding fall in elongation. Annealing raises the elongation but reduces the tensile strength and hardness. Furthermore, corrosion resistance of nickel-aluminum bronze ranks from worse to better in the following order: aged, quenched, normalized, hot-extruded and annealed. However, with the exposure time of corrosion test increasing, the difference of average corrosion rate between those nickel-aluminum bronzes tums small.

  18. Evaluation of the inhibitive effect of benzotriazole on archeological bronze in acidic medium

    Science.gov (United States)

    Hassairi, Hèla; Bousselmi, Latifa; Khosrof, Slim; Triki, Ezzeddine

    2013-12-01

    An archaeological bronze artefact was a Punic coin excavated from the north east of Tunisia in 2001. The composition of the copper alloy revealed a content of 3.5 % of tin and 1.4 % of lead with the presence of some sulphur heterogeneity. The surface presents some roughnesses and cracks and is covered by a corrosion layer of 20-40 μm thickness. The use of benzotriazole (BTA) as an inhibitor has become a standard element for the preservation of cuprous-based metals. In order to investigate the behaviour of BTA in an acidic medium, an Electrochemical Impedance Spectroscopy (EIS) investigation was performed to characterize the electrochemical behaviour of the interface of the archaeological bronze sample/acidic medium without and with BTA addition. Impedance diagrams obtained at different immersion times show that the presence of the inhibitor prevents the diffusional process observed in the absence of BTA. The inhibition of the pre-polarized bronze surface revealed that the mechanism of action of the benzotriazole molecule in an acidic medium is governed by the chemisorption process.

  19. Analysis of the Quintilii’s Villa Bronzes by Spectroscopy Techniques

    Directory of Open Access Journals (Sweden)

    Fabio Stranges

    2014-01-01

    Full Text Available The aim of this work is the characterization, with different diagnostic tests, of three fragments of bronze artefacts recovered from the Villa of the Quintilii (located in the south of Rome. In particular, the sample alloys were investigated by different chemical and morphological analysis. Firstly, an analysis of the alloy, implemented through the electronic spectroscopy, was taken to discriminate the bronze morphology and its elemental composition. Subsequently, a surface analysis was realized by molecular spectroscopy to identify the alteration patinas on surfaces (such as bronze disease. Two diagnostic techniques are used for the alloy analysis: scanning electron microscopy (SEM connected to the EDX spectroscopy (to study the morphology and alloy composition and Auger electron spectroscopy (AES (to identify the oxidation state of each element. Moreover, for the study of surface patinas, IR and Raman spectroscopies were implemented. All studies were performed on the “as received” samples, covered by a thin layer of excavated soil and on samples processed in an aqueous solution of sulphuric acid (10%, to remove patinas and alterations.

  20. Danaparoid sodium.

    Science.gov (United States)

    Acostamadiedo, J M; Iyer, U G; Owen, J

    2000-05-01

    Danaparoid sodium (Orgaran, Organon) is a heparinoid glycosamino-glycuronan antithrombotic agent approved for the prophylaxis of post-operative deep vein thrombosis (DVT), which may lead to pulmonary embolism (PE) in patients undergoing elective hip replacement surgery. Danaparoid is a low molecular weight heparinoid consisting of a mixture of heparan sulphate (84%), dermatan sulphate (12%) and small amounts of chondroitin sulphate (4%), whose antithrombotic activity has been well established. Its pharmacological effect is exerted primarily by inhibiting Factors Xa (FXa) and IIa (FIIa) at a ratio greater than heparin, with a minimal effect on platelet function. Danaparoid exhibits low cross-reactivity with heparin-induced antibodies when compared with heparin or low molecular weight heparins (LMWH), thereby making it an excellent choice for the management of heparin-induced thrombocytopenia (HIT). It has excellent bioavailability following s.c. injection. Danaparoid has little effect on routine coagulation tests (activated partial thromboplastin time [aPTT], prothrombin time [PT], and thrombin time [TT]). Patients with elevated serum creatinine should be monitored carefully. For its FDA approved indication (DVT prophylaxis during hip replacement surgery), its cost per day is approximately eight times more than LMWH. Even though monitoring is not routinely necessary according to the manufacturer for its approved indication, monitoring is frequently necessary when it is used in other clinical scenarios. Its higher cost than comparable therapies for DVT prophylaxis and the low availability of the FXa assay in most non-tertiary care hospitals has limited the widespread use of danaparoid. Danaparoid has been found to be effective in the treatment of HIT although this is an off label use, despite being the most frequent reason why danaparoid is used. PMID:11249517

  1. A systematic approach to Bronze corrosion products and the methods of treatment , applied on three bronze anklets from Dhamar museum , Yemen

    Directory of Open Access Journals (Sweden)

    Hazem Mohamed

    2014-04-01

    Full Text Available Three bronze anklets were found during the archaeological excavation of Yemeni mission 2002 A.D, in Gabal al- lawd , Jawf area , Yemen , they dated back to Minaean period in Yemen [sixth century B.C – 24 B.C] , and now they are situated in Dhamar regional museum .They were suffered from the deterioration aspects , two of these anklets had a thick corrosion products of pale green / brown , the third anklet had a rust-colored Black and Brown with the presence of small parts and scattered pale green. The aim of this paper is to examine, in detail, the corrosion of the selected objects that was grown during the long-term burial and identify its products that will help us to understand the corrosive factors and the degradation mechanisms , as well as their constituting metals in order to carry out scientific treatment and conservation .For this purpose ,samples from the objects were examined by Metallographic Microscope (ME , Scanning Electron Microscope (SEM, the corrosion products were analyzed by X-ray diffraction (XRD and X-ray fluorescence( XRF was used to determine the objects metallic constituents . XRD data showed that the corrosion products constitute of cuprite , atacamite , and paratacamite , whereas XRF analysis declared that the anklets compose of bronze alloy . Microscopic examination reveals that the three anklets were suffered from the deterioration spots , which dispersed on the metal surface . Chemical cleaning was chosen for treating the objects , finally they were isolated to preserve them against further attack.

  2. CALICE silicon-tungsten electromagnetic calorimeter

    Indian Academy of Sciences (India)

    G Mavromanolakis

    2007-12-01

    A highly granular electromagnetic calorimeter prototype based on tungsten absorber and sampling units equipped with silicon pads as sensitive devices for signal collection is under construction. The full prototype will have in total 30 layers and be read out by about 10000 Si cells of 1 × 1 cm2. A first module consisting of 14 layers and depth of 7.2 0 at normal incidence, having in total 3024 channels of 1 cm2, was tested recently with - beam. We describe the prototype and discuss some preliminary testbeam results on its performance with respect to position resolution, response inhomogeneity and transverse containment.

  3. Tungsten imido catalysts for selective ethylene dimerisation.

    Science.gov (United States)

    Wright, Christopher M R; Turner, Zoë R; Buffet, Jean-Charles; O'Hare, Dermot

    2016-02-14

    A tungsten imido complex W(NDipp)Me3Cl (Dipp = 2,6-(i)Pr-C6H3) is active for the selective dimerisation of ethylene to yield 1-butene under mild conditions. Immobilisation and activation of W(NDipp)Cl4(THF) on layered double hydroxides, silica or polymethylaluminoxane yields active solid state catalysts for the selective dimerisation of ethylene. The polymethylaluminoxane-based catalyst displays a turnover frequency (4.0 molC2H4 molW(-1) h(-1)) almost 7 times that of the homogeneous catalyst. PMID:26779579

  4. Tungsten imido catalysts for selective ethylene dimerisation.

    Science.gov (United States)

    Wright, Christopher M R; Turner, Zoë R; Buffet, Jean-Charles; O'Hare, Dermot

    2016-02-14

    A tungsten imido complex W(NDipp)Me3Cl (Dipp = 2,6-(i)Pr-C6H3) is active for the selective dimerisation of ethylene to yield 1-butene under mild conditions. Immobilisation and activation of W(NDipp)Cl4(THF) on layered double hydroxides, silica or polymethylaluminoxane yields active solid state catalysts for the selective dimerisation of ethylene. The polymethylaluminoxane-based catalyst displays a turnover frequency (4.0 molC2H4 molW(-1) h(-1)) almost 7 times that of the homogeneous catalyst.

  5. Preparation and Electrocatalytic Activity of Tungsten Carbide Nanorod Arrays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    High density tungsten carbide nanorod arrays have been prepared by magnetron sputtering (MS) using the aluminum lattice membrane (ALM) as template. Electrocatalytic properties of nitromethane electroreduction on the tungsten carbide nanorod arrays electrode were investigated by electrochemical method, and their electrocatalytic activity is approached to that of the Pt foil electrode.

  6. Sodium removal from sodium wetted under sodium ultra sonic scanner

    International Nuclear Information System (INIS)

    Highlights: ► Sodium wetted USUSS was subjected to sodium cleaning by water vapour–CO2 process. ► Hydrogen released during the process was monitored and regulated in safe limit. ► The temperature of USUSS was maintained below 80 °C to prevent caustic corrosion. ► The experiment revealed intricacies involved in the cleaning operation. ► The operational parameters for safe cleaning were optimised. - Abstract: Sodium is used as a coolant in primary and secondary heat transport systems of Liquid Metal cooled Fast Breeder Reactors (LMFBR). The Prototype Fast Breeder Reactor (PFBR) is in advanced stage of construction at Kalpakkam, India. Under Sodium Ultra Sonic Scanner (USUSS) is used to image the components dipped in sodium and more specifically the gap between Sub Assembly (SA) heads and the control plug. This is essential to confirm that no SA is protruding from its position. USUSS has to be qualified in sodium before its use in the reactor. After sodium testing, sodium adhering to the USUSS needs to be removed to prevent reaction with oxygen and moisture present in air when it is taken out. The sodium removal process is based on the use of moist carbon-di-oxide (CO2) at a temperature of about 353 K. The reaction rate is controlled by varying the ratio of CO2 to moisture. Hydrogen released during the reaction of sodium with moisture is continuously monitored to ensure safe limits of hydrogen concentration. This paper describes the details of the experimental setup used in a cleaning pit for the removal of sodium adhering on USUSS and the technical details of the cleaning process.

  7. The Relationship Between Ambiently Formed Oxides and the Tribological Behavior of Aluminum Bronze

    Science.gov (United States)

    Poggie, Robert Andre

    1992-01-01

    The relationship between ambiently formed oxides and the tribological behavior of aluminum bronze has been investigated. As the aluminum content of Al-bronze increases from zero to eight weight percent, the mechanical properties, oxidation kinetics, and tribological behavior of the alloy are significantly affected. This research has shown that the friction and wear behavior of Al-bronze depends primarily on the composition and mechanical stability of the ambiently formed surface oxide. Adhesive transfer of Al-bronze to the slider counterfaces increased with increasing aluminum content which corresponded to increased damage to the alloy surfaces and the formation of wear debris. The majority of surface damage (plastic deformation and galling) of the Cu-4 and 6 w/o Al alloys occurred during the initial portion (run-in) of wear testing. The Cu-1 w/o Al alloy wore via an oxidative wear mechanism throughout the course of wear testing. Galling, severe plastic deformation, the formation of metallic wear debris, and adhesive transfer were not observed for the Cu-1 AL w/o alloy. XPS and SEM analysis of the Cu-1 w/o Al alloy showed the worn surfaces to consist of a smooth and adherent Cu_2O layer. Long term ambient oxidation of the Cu-4 and 6 w/o Al alloys resulted in a layered oxide structure with Cu(OH)_2 at the surface followed by CuO, Cu_2O, Al_2O_3, and, lastly, the metallic substrate. The differences in elastic moduli, crystal structures, and composition between the copper alloy and the Al _2O_3 enriched surface oxide decreases the mechanical integrity of the surface oxide. The tensile and compressive stresses generated at the surface of the Al-bronze samples via frictional interaction with the opposing slider is sufficient to cause a large differential in strain across the oxide-metal interface and disruption of the brittle, Al_2O _3 enriched surface oxide. The exposed metal immediately repassivates itself by reforming a surface oxide or forming an adhesive bond with

  8. Tungsten recycling in the United States in 2000

    Science.gov (United States)

    Shedd, Kim B.

    2011-01-01

    This report, which is one of a series of reports on metals recycling, defines and quantifies the flow of tungsten-bearing materials in the United States from imports and stock releases through consumption and disposition in 2000, with particular emphasis on the recycling of industrial scrap (new scrap) and used products (old scrap). Because of tungsten's many diverse uses, numerous types of scrap were available for recycling by a wide variety of processes. In 2000, an estimated 46 percent of U.S. tungsten supply was derived from scrap. The ratio of tungsten consumed from new scrap to that consumed from old scrap was estimated to be 20:80. Of all the tungsten in old scrap available for recycling, an estimated 66 percent was either consumed in the United States or exported to be recycled.

  9. Plasma spray forming of tungsten coatings on copper electrodes

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-liang(蒋显亮); F.Gitzhofer; M.I.Boulos

    2004-01-01

    Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.

  10. A study on consumable aided tungsten indirect arc welding

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Wang Yuxin; Feng Jicai

    2009-01-01

    A consumable aided tungsten indirect arc welding method has been studied. This method is different from the traditional TIG welding because it introduces an MIG welding torch into the traditional TIG welding system. An indirect arc is generated between the consumable electrode of the MIG welding torch and the tungsten electrode of the TIG welding torch, but not generated between the tungsten electrode of the welding torch and the base metal. Welding current flows from the consumable electrode to the tungsten electrode in the free-burning indirect arc. The consumable aided tungsten indirect arc welding not only rapidly melts the welding wire but also effectively restrains the excessive fusion of the base metal. The welding experiment and the theoretical analysis confirm that this method can obtain a high deposition rate and a low dilution ratio during the welding process.

  11. Spreading of Ni - Fe - W melts over polycrystalline tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Yupko, V.L.; Minakova, R.V.; Kolchin, O.P.; Vodop' yanova, L.S.; Monastyreva, N.I.; Vojtenko, V.L. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya)

    1983-09-01

    The method of filming was employed to study the spread over dense and porous polycrystalline tungsten of Ni-Fe-W melts. When tungsten amount grows and the W-(Ni-Fe-W) system approaches the thermodynamic equilibrium state the melts spread deteriorates; in case of porous tungsten it is worse than in case of dense one. The observed porosity effect on the spread testifies to intensification of the liquid motion turbulence. Difference in the spread over polycrystalline tungsten between melts with a constant tungsten content (24%) and with the Ni:Fe ratio varying over wide ranges is within the limits of the experimental error, which is due to similar physicochemical properties of nickel and iron.

  12. Microstructural characterization and field emission properties of tungsten oxide and titanium-oxide-doped tungsten oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chia-Hsiang [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan (China); Su, Cherng-Yuh, E-mail: cysu@ntut.edu.tw [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Yan-Fu [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China)

    2015-03-01

    Tungsten oxide and titanium-oxide-doped tungsten oxide nanowires were synthesized by using the DC magnetron sputtering and infrared furnace annealing processes. Scanning election microscopy (SEM) and transmission electron microscopy (TEM) were utilized to evaluate the topography and sizes. X-ray diffraction (XRD), grazing incidence X-ray diffraction (GI-XRD), and high-resolution transmission electron microscopy (HRTEM) were used to analyze the composition and structure. From the results of HRTEM, it was discovered that the prepared nanowires have a monoclinic single-crystal phase of W{sub 18}O{sub 49} with lattice growth along the (010) lattice plane, and the lattice spacing is 0.378 nm, which agrees with XRD and GI-XRD results. The prepared tungsten oxide and titanium-oxide-doped tungsten oxide nanowires have turn-on voltage of 3.06 V/μm and 1.46 V/μm respectively. They also possess superior field enhancement factors of 5103 and 10667 respectively. Their behavior thus follows the Fowler-Nordheim expression for tunneling. - Highlights: • A simple method to prepare tungsten oxide nanowires by annealing tungsten film. • High aspect ratio of the 1D titanium-oxide-doped tungsten oxide nanowires. • High field enhancement factor of titanium-oxide-doped tungsten oxide nanowires.

  13. Concentration dependent hydrogen diffusion in tungsten

    Science.gov (United States)

    Ahlgren, T.; Bukonte, L.

    2016-10-01

    The diffusion of hydrogen in tungsten is studied as a function of temperature, hydrogen concentration and pressure using Molecular Dynamics technique. A new analysis method to determine diffusion coefficients that accounts for the random oscillation of atoms around the equilibrium position is presented. The results indicate that the hydrogen migration barrier of 0.25 eV should be used instead of the presently recommended value of 0.39 eV. This conclusion is supported by both experiments and density functional theory calculations. Moreover, the migration volume at the saddle point for H in W is found to be positive: ΔVm ≈ 0.488 Å3, leading to a decrease in the diffusivity at high pressures. At high H concentrations, a dramatic reduction in the diffusion coefficient is observed, due to site blocking and the repulsive H-H interaction. The results of this study indicates that high flux hydrogen irradiation leads to much higher H concentrations in tungsten than expected.

  14. Dynamic compaction of tungsten carbide powder.

    Energy Technology Data Exchange (ETDEWEB)

    Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward

    2005-04-01

    The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.

  15. Lead isotopic study of Shang Dynasty bronzes (13-11 B.C.) and their ore sources

    International Nuclear Information System (INIS)

    The Shang Dynasty civilization in China is based on the development of the bronze techniques. A large amount of Shang Dynasty bronzes, excavated from Jiangxi, Hubei and Henan Provinces, have become a focus of world attention. However, the Shang Dynasty center was located at Zhenzhou and Anyang city areas, Henan Province, where no large copper ores have been found so far. Therefore, where did the huge ore material for casting the bronzes come from? It is an unsettled question paid attention by the archaeologists and scientists. 35 Shang Dynasty bronzes and 21 copper and lead ore materials aged in the Shang-Zhou Dynasty, the Spring-Autumn Period and the modern time, have been measured by the use of mass spectrometry. Based upon lead isotopic ratios, the ore material for casting the bronzes with the middle isotopic ratios of 207Pb/206Pb ranged in 0.8∼0.9 could come from the ancient copper mine of Tongling, Jiangxi Province and Tong Lushan , Hubei Province and that with the high isotopic ratios (>0.9) could be from the northern part of the Shang Empire, called 'Gongfang' in the historical records, e.g. today's Hebei and Liaoning Provinces. the others with the low isotopic ratios (238U/204Pb in the ore flux or in the magma

  16. Highly efficient ablation of metastatic breast cancer using ammonium-tungsten-bronze nanocube as a novel 1064 nm-laser-driven photothermal agent.

    Science.gov (United States)

    Guo, Chongshen; Yu, Haijun; Feng, Bing; Gao, Weidong; Yan, Mei; Zhang, Zhiwen; Li, Yaping; Liu, Shaoqin

    2015-06-01

    Photothermal ablation (PTA) therapy has been viewed as an invasive option for cancer therapy with minimal deconstruction of healthy tissues. In this study, a potent candidate of (NH4)xWO3 nanocube was developed for PTA treatment of metastatic breast cancer in the second near-infrared (NIR) window. It was found that the as-synthesized (NH4)xWO3 nanocube had significant photoabsorption across the whole NIR window of 780-2500 nm and exhibited considerable photo-heat conversion efficiency. Moreover, the as-prepared (NH4)xWO3 nanocube displayed good biocompatibility and high cellular uptake efficiency through endocytosis pathway without nuclei entry. The PTA study employing 1064 nm laser in the second NIR window revealed that (NH4)xWO3 nanocubes induced significant cell necrosis and apoptosis by producing obviously hyperthermia effect inside cancer cells. Using an orthotopicly implanted breast tumor model, it demonstrated that the (NH4)xWO3 nanocube was a promising photothermal agent for effective ablation of solid tumors and suppressing their distant metastasis. PMID:25818447

  17. Tungsten transport in the plasma edge at ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Janzer, Michael Arthur

    2015-04-30

    The Plasma Facing Components (PFC) will play a crucial role in future deuterium-tritium magnetically confined fusion power plants, since they will be subject to high energy and particle loads, but at the same time have to ensure long lifetimes and a low tritium retention. These requirements will most probably necessitate the use of high-Z materials such as tungsten for the wall materials, since their erosion properties are very benign and, unlike carbon, capture only little tritium. The drawback with high-Z materials is, that they emit strong line radiation in the core plasma, which acts as a powerful energy loss mechanism. Thus, the concentration of these high-Z materials has to be controlled and kept at low levels in order to achieve a burning plasma. Understanding the transport processes in the plasma edge is essential for applying the proper impurity control mechanisms. This control can be exerted either by enhancing the outflux, e.g. by Edge Localized Modes (ELM), since they are known to expel impurities from the main plasma, or by reducing the influx, e.g. minimizing the tungsten erosion or increasing the shielding effect of the Scrape Off Layer (SOL). ASDEX Upgrade (AUG) has been successfully operating with a full tungsten wall for several years now and offers the possibility to investigate these edge transport processes for tungsten. This study focused on the disentanglement of the frequency of type-I ELMs and the main chamber gas injection rate, two parameters which are usually linked in H-mode discharges. Such a separation allowed for the first time the direct assessment of the impact of each parameter on the tungsten concentration. The control of the ELM frequency was performed by adjusting the shape of the plasma, i.e. the upper triangularity. The radial tungsten transport was investigated by implementing a modulated tungsten source. To create this modulated source, the linear dependence of the tungsten erosion rate at the Ion Cyclotron Resonance

  18. Tungsten transport in the plasma edge at ASDEX upgrade

    International Nuclear Information System (INIS)

    The Plasma Facing Components (PFC) will play a crucial role in future deuterium-tritium magnetically confined fusion power plants, since they will be subject to high energy and particle loads, but at the same time have to ensure long lifetimes and a low tritium retention. These requirements will most probably necessitate the use of high-Z materials such as tungsten for the wall materials, since their erosion properties are very benign and, unlike carbon, capture only little tritium. The drawback with high-Z materials is, that they emit strong line radiation in the core plasma, which acts as a powerful energy loss mechanism. Thus, the concentration of these high-Z materials has to be controlled and kept at low levels in order to achieve a burning plasma. Understanding the transport processes in the plasma edge is essential for applying the proper impurity control mechanisms. This control can be exerted either by enhancing the outflux, e.g. by Edge Localized Modes (ELM), since they are known to expel impurities from the main plasma, or by reducing the influx, e.g. minimizing the tungsten erosion or increasing the shielding effect of the Scrape Off Layer (SOL). ASDEX Upgrade (AUG) has been successfully operating with a full tungsten wall for several years now and offers the possibility to investigate these edge transport processes for tungsten. This study focused on the disentanglement of the frequency of type-I ELMs and the main chamber gas injection rate, two parameters which are usually linked in H-mode discharges. Such a separation allowed for the first time the direct assessment of the impact of each parameter on the tungsten concentration. The control of the ELM frequency was performed by adjusting the shape of the plasma, i.e. the upper triangularity. The radial tungsten transport was investigated by implementing a modulated tungsten source. To create this modulated source, the linear dependence of the tungsten erosion rate at the Ion Cyclotron Resonance

  19. Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia

    DEFF Research Database (Denmark)

    Sørensen, Lasse

    2012-01-01

    Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia......Pioneering farmers cultivating new lands in the North – The expansion of agrarian societies during the Neolithic and Bronze Age in Scandinavia...

  20. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    Science.gov (United States)

    Fukuda, Makoto; Kiran Kumar, N. A. P.; Koyanagi, Takaaki; Garrison, Lauren M.; Snead, Lance L.; Katoh, Yutai; Hasegawa, Akira

    2016-10-01

    Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). To investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ∼90-∼800 °C and fast neutron fluences were 0.02-9.00 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 1025 n/m2 (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.

  1. Nonlinear Saturable Absorption of Liquid-Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets.

    Science.gov (United States)

    Mao, Dong; Du, Bobo; Yang, Dexing; Zhang, Shengli; Wang, Yadong; Zhang, Wending; She, Xiaoyang; Cheng, Huachao; Zeng, Haibo; Zhao, Jianlin

    2016-03-01

    Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 μm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators. PMID:26800122

  2. COMPUTER NUMERICAL SIMULATION OF MECHANICAL PROPERTIES OF TUNGSTEN HEAVY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A microstructure model of tungsten heavy alloys has been developed. On the basis of the model and several assumptions, the macro-mechanical properties of 90 W heavy alloy under quasi-static tensile deformation and the effects of microstructural parameters (mechanical properties of the matrix phase and tungsten content) on them have been analyzed by computer numerical simulation. The mechanical properties of the alloy have been found to be dependent on the mechanical parameters of the matrix phase. As the elastic modulus and yield strength of the matrix phase increase, the tensile strength of the alloy increases, while the elongation decreases. If the mechanical parameters except the tensile strength of the matrix phase are constant, both the tensile strength and the elongation of the alloy increase linearly with the increase of tensile strength of the matrix phase. The properties of the alloy are very sensitive to the hardening modulus of the matrix phase. As the hardening modulus increases, both the tensile strength and the elongation of the alloy exponentially decrease. The elongation of the alloys monotonically decreases with the increase of tungsten content, while the decrease of tensile strength is not monotonic. When the tungsten content < 85 %, the strength of tungsten heavy alloys increases with the increase of tungsten content, while decreases when the tungsten content >85 %. The maximum of tensile strength of the alloys appears at the tungsten content of 85 %. The results showed that the binder phase with a higher strength and a lower hardening modulus is advantageous to obtaining an optimum combination of mechanical properties of tungsten heavy alloys.

  3. High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap

    Directory of Open Access Journals (Sweden)

    Han Chulwoong

    2015-06-01

    Full Text Available Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.

  4. Neutron irradiation effects on the microstructural development of tungsten and tungsten alloys

    Science.gov (United States)

    Hasegawa, Akira; Fukuda, Makoto; Yabuuchi, Kiyohiro; Nogami, Shuhei

    2016-04-01

    Data on the microstructural development of tungsten (W) and tungsten rhenium (Re) alloys were obtained after neutron irradiation at 400-800 °C in the Japan Materials Testing Reactor (JMTR), the experimental fast test reactor Joyo, and the High Flux Isotope Reactor (HFIR) for irradiation damage levels in the range of 0.09-1.54 displacement per atom (dpa). Microstructural observations showed that a small amount of Re (3-5%) in W-Re alloys is effective in suppressing void formation. In W-Re alloys with Re concentrations greater than 10%, acicular precipitates are the primary structural defects. In the HFIR-irradiated specimen, in which a large amount of Re was expected to be produced by the nuclear transmutation of W to Re because of the reactor's high thermal neutron flux, voids were not observed even in pure W. The synergistic effects of displacement damage and solid transmutation elements on microstructural development are discussed, and the microstructural development of tungsten materials utilized in fusion reactors is predicted.

  5. Mechanisms of selectivity loss during tungsten CVD (chemical vapor deposition)

    Energy Technology Data Exchange (ETDEWEB)

    Creighton, J.R.

    1990-01-01

    The tungsten subfluoride mechanism as well as other proposed mechanisms of selectivity loss are reviewed. To further demonstrate the viability of the tungsten subfluoride mechanism, we have extended the measurement of the tungsten subfluoride production rate down to 450{degree}C. We also report results from some preliminary experiments designed to identify the selectivity loss mechanism when elemental silicon is available for reaction. Comments regarding the origins of the insulator effect and selectivity loss for silane reduction are offered. 23 refs., 2 figs.

  6. Raman study of thermochromic phase transition in tungsten trioxide nanowires

    Science.gov (United States)

    Lu, Dong Yu; Chen, Jian; Chen, Huan Jun; Gong, Li; Deng, Shao Zhi; Xu, Ning Sheng; Liu, Yu Long

    2007-01-01

    Tungsten trioxide (WO3) nanowires were synthesized by thermal evaporation of tungsten powder in two steps: tungsten suboxide (WO3-x) nanowires were synthesized, and then oxidized in O2 ambient and transformed into WO3 nanowires. Raman spectroscopy was applied to study the thermochromic phase transition of one-dimensional WO3 nanowires. From the temperature dependence of the characteristic mode at 33cm-1 in WO3, the phase transition temperature was determined. It was found that the phase transition of WO3 nanowires was reversible and the phase transition temperatures were even lower than that of WO3 nanopowder.

  7. Electrode potentials of tungsten in fused alkali chlorides

    Science.gov (United States)

    Ivanov, A. B.; Volkovich, V. A.; Poskryakov, D. A.; Vasin, B. D.; Griffiths, T. R.

    2016-09-01

    Anodic dissolution of tungsten was studied at 823-1173 K in the melts based on NaCl-CsCl, NaCl-KCl-CsCl and LiCl-KCl-CsCl eutectic mixtures. The process results in the formation of W(IV) ions. Prolonged contact with silica results in oxidation W(IV) ions and decreasing tungsten concentration in the electrolyte due to formation of volatile higher oxidation state chloro- and oxychloro-species. Tungsten electrode potentials were measured in NaCl-CsCl and NaCl-KCl-CsCl based melts using potentiometry.

  8. Preparation of nanocomposite thoriated tungsten cathode by swaging technique

    Institute of Scientific and Technical Information of China (English)

    王发展; 诸葛飞; 张晖; 丁秉钧

    2002-01-01

    By using the high energy ball milling method,the nanosized ThO2 powders were obtained.Through mixing powders,sintering and hot swaging processing,a nanocomposite thoriated tungsten cathode was fabricated.The relative density of the nanocomposite material is near 100%.The microstructure of nanocomposite cathode is quite different from that of conventional thoriated tungsten cathode.Most of thoria particles are less than 100 nm in diameter,and distribute on the boundaries of tungsten grains.The nanocomposite cathode shows a much lower arc starting field than that of conventional cathode,which will improve the performance of the cathode significantly.

  9. Microstructure and mechanical properties of Ti6Al4V/Cu-10Sn bronze diffusion-bonded joint

    Institute of Scientific and Technical Information of China (English)

    ZHAO He; CAO Jian; FENG Ji-cai

    2009-01-01

    The microstructures and mechanical properties of Ti6Al4V/Cu-10Sn bronze diffusion-bonded joint were studied via scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS). Diffusion bonding of Ti6Al4V to Cu-10Sn bronze was investigated at different holding time. Four obvious interracial layers were observed in the joint. It is revealed that the bonding joint has high shear strength up to 102 MPa bonded at 830 ℃, bonding pressure 10 MPa and bonding time 15 min. Shear test results show that the fracture takes place between the reaction layer and the Cu-10Sn bronze substrate, and the shear strength is strongly related to the formation of Cu-Ti-Sn intermetallic compounds.

  10. Corrosion and wear behaviors of Al-bronzes in 5.0% H2SO4 solution

    Institute of Scientific and Technical Information of China (English)

    LI Wen-sheng; WANG Zhi-ping; LU Yang; YUAN Li-hua; XIAO Rong-zhen; ZHAO Xu-dong

    2009-01-01

    Steady-state corrosion and wear behaviors of two Al-bronzes, Cu-14Al-X and QAl9-4, in 5.0% H2SO4 solution were investigated. It is found that wear loss of bronzes in 5.0% H2SO4 solution is lower than that in water or in air, namely, it exhibits negative synergy between corrosion and wear. Further analysis shows that corrosive solution plays an important role in cooling of specimen during the sliding wear to prevent the reduction of the surface hardness of specimen, induced by frictional heat. On the other hand, the bronzes suffer a de-alloying corrosion, and a noble copper subsurface and patina form on the specimen surface in corrosive solution, which has a passive function for further corrosion. The noble copper subsurface experiences strain hardening during the corrosion and wear, resulting in the increase of the surface hardness thus the increase in wear resistance.

  11. A Preliminary Study of Bronzes in the Kayao Culture%卡约文化青铜器初步研究

    Institute of Scientific and Technical Information of China (English)

    三宅俊彦

    2005-01-01

    A chronological study of its pottery suggests that the Kayao culture remains can be divided into the groups of Huangshui River and Yellow River valleys and each group fall into six phases.On this basis the typology and combination of bronzes in the Kayao culture can be further studied. The results indicate that bronze-making technology in the Huangshui River valley was higher than that in the Yellow River valley, and that the sexual difference of tomb-owners is reflected from the distinction of funeral objects. Furthermore, the chronological study of the Kayao's bronzes provides reference data for dating the phases of this culture. These bronzes possess three categories of cultural elements: the elements of their own, common elements of bronzes in the Central Plains and North China, and those in northern Eurasia.

  12. Tungsten Oxide and Polyaniline Composite Fabricated by Surfactant-Templated Electrodeposition and Its Use in Supercapacitors

    Directory of Open Access Journals (Sweden)

    Benxue Zou

    2014-01-01

    Full Text Available Composite nanostructures of tungsten oxide and polyaniline (PANI were fabricated on carbon electrode by electrocodeposition using sodium dodecylbenzene sulfonate (SDBS as the template. The morphology of the composite can be controlled by changing SDBS surfactant and aniline monomer concentrations in solution. With increasing concentration of aniline in surfactant solution, the morphological change from nanoparticles to nanofibers was observed. The nanostructured WO3/PANI composite exhibited enhanced capacitive charge storage with the specific capacitance of 201 F g−1 at 1.28 mA cm−2 in large potential window of -0.5~ 0.65 V versus SCE compared to the bulk composite film. The capacitance retained about 78% when the sweeping potential rate increased from 10 to 150 mV/s.

  13. Stoner-enhanced paramagnetism in tungsten tetraboride

    International Nuclear Information System (INIS)

    We demonstrate that tungsten tetraboride (WB4), a heavy transition metallic compound without magnetic atoms, is an exchange-enhanced paramagnet revealed by the magnetization and specific heat measurements. WB4 has a small effective magnetic moment of 0.53 μ B/fu. The high magnetic susceptibility in the magnitude of 1 memu (mol·Oe)−1 below 10 K obeys quadratic temperature dependence. The upturn behavior of C P/T versus T 2 at low temperatures is attributed to the electron-paramagnon interactions. A high Stoner enhancement parameter, Z  =  0.93, was derived to explain the enhanced paramagnetism based on the Stoner model. (paper)

  14. Docusate Sodium and Pregnancy

    Science.gov (United States)

    ... live chat Live Help Fact Sheets Share Docusate Sodium Friday, 01 April 2016 In every pregnancy, a ... This sheet talks about whether exposure to docusate sodium may increase the risk for birth defects over ...

  15. Diclofenac sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002630.htm Diclofenac sodium overdose To use the sharing features on this page, please enable JavaScript. Diclofenac sodium is a prescription medicine used to relieve pain ...

  16. Naproxen sodium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002507.htm Naproxen sodium overdose To use the sharing features on this page, please enable JavaScript. Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used ...

  17. Preparation and characterization of electrochromic tungsten oxide–titania composite thin films with different tungsten/titanium ratios

    International Nuclear Information System (INIS)

    Tungsten oxide–titania composite thin films with different W/Ti atomic ratios were prepared and characterized in this study. Surface morphology, composition and structure of the composite thin films were investigated by scanning electron microscope with an energy dispersive spectrometer, X-ray diffraction and atomic force microscope analyses. Electrochromic properties including transmittance modulation ability, coloration efficiency and coloring/bleaching response time of these thin films were examined using cyclic voltammetry and double-potential-step experiment with in-situ ultraviolet–visible spectroscopy measurement. The presence of titania in the composite thin film could inhibit the crystal growth of tungsten oxide, which enhances the transmittance modulation ability and coloration efficiency but prolongs the coloring/bleaching response time of the composite thin film. The tungsten oxide–titania composite thin film (WTi-30) with a W/Ti atomic ratio of 78/22 exhibited better transmittance modulation ability (57.5%) and coloration efficiency (49.2 cm2/C) than a pristine tungsten trioxide thin film (53.6%, 36.2 cm2/C). - Highlights: • Tungsten oxide–titania thin films with different W/Ti atomic ratios are prepared. • Tungsten oxide and titania were well mixed in the composite thin films. • Crystal growth of tungsten oxide was inhibited by the incorporation of titania. • Transmittance modulation ability of the composite thin film is increased. • Coloration efficiency of the composite thin film is enhanced

  18. Preparation and characterization of electrochromic tungsten oxide–titania composite thin films with different tungsten/titanium ratios

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Cheng-Lan, E-mail: cllin@mail.tku.edu.tw [Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 25137, Taiwan (China); The Energy and Opto-Electronic Materials Research Center, Tamkang University, New Taipei City 25137, Taiwan (China); Chen, Yan-Wen; Chen, En [Department of Chemical and Materials Engineering, Tamkang University, New Taipei City 25137, Taiwan (China)

    2014-04-01

    Tungsten oxide–titania composite thin films with different W/Ti atomic ratios were prepared and characterized in this study. Surface morphology, composition and structure of the composite thin films were investigated by scanning electron microscope with an energy dispersive spectrometer, X-ray diffraction and atomic force microscope analyses. Electrochromic properties including transmittance modulation ability, coloration efficiency and coloring/bleaching response time of these thin films were examined using cyclic voltammetry and double-potential-step experiment with in-situ ultraviolet–visible spectroscopy measurement. The presence of titania in the composite thin film could inhibit the crystal growth of tungsten oxide, which enhances the transmittance modulation ability and coloration efficiency but prolongs the coloring/bleaching response time of the composite thin film. The tungsten oxide–titania composite thin film (WTi-30) with a W/Ti atomic ratio of 78/22 exhibited better transmittance modulation ability (57.5%) and coloration efficiency (49.2 cm{sup 2}/C) than a pristine tungsten trioxide thin film (53.6%, 36.2 cm{sup 2}/C). - Highlights: • Tungsten oxide–titania thin films with different W/Ti atomic ratios are prepared. • Tungsten oxide and titania were well mixed in the composite thin films. • Crystal growth of tungsten oxide was inhibited by the incorporation of titania. • Transmittance modulation ability of the composite thin film is increased. • Coloration efficiency of the composite thin film is enhanced.

  19. Analysis of the Portevin - Le Chatelier effect in tin bronzes at elevated temperatures

    Directory of Open Access Journals (Sweden)

    W. Ozgowicz

    2008-12-01

    Full Text Available Purpose: The aim of the present paper is the determination of the effect of the chemical composition and temperature of deformation of standardized tin bronzes and bronze modified with zirconium on the Portevin – Le Chatelier (PLC phenomenon, mainly basing on the shape of stress-strain curves within the temperature range of 100-300oC and observations of their structure. The reasons of the occurrence of such en effect are so far no fully known and explained and the opinions concerning is physical basis vary.Design/methodology/approach: Of essential design in this research is determination of the dependence of PLC effect on the chemical composition, temperature and strain rate and the preliminary heat treatment and grain size. The main method used in this investigation is tensile test at elevated temperature.Findings: The main conclusions are following: the PLC effect on tin bronzes with a micro-addition of zirconium in an amount of 0.01-0.05% depends the temperature of deformation in the tensile test in the range of 100-300oC and the chemical composition of the alloys; the type of serration revealed on the σ–ε curve depend mainly on the temperature of deformation and can be differ during the respective stages of the analyzed curves.Practical implications: In this paper implications for practice are not taken into consideration.Originality/value: In this paper an additive type of serration observed on the curves σ–ε, denoted by the symbol D, is new.

  20. On the degradation factors of an archaeological bronze bowl belonging to a private collection

    Energy Technology Data Exchange (ETDEWEB)

    Soffritti, C., E-mail: chiara.soffritti@unife.it [TekneHub, Department of Architecture, University of Ferrara, Via Quartieri 8, 44122 Ferrara (Italy); Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Fabbri, E., E-mail: elettra.fabbri@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Merlin, M., E-mail: mattia.merlin@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Garagnani, G.L., E-mail: gian.luca.garagnani@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); “A. Daccò” Corrosion and Metallurgy Study Centre, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Monticelli, C., E-mail: cecilia.monticelli@unife.it [Department of Engineering, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy); “A. Daccò” Corrosion and Metallurgy Study Centre, University of Ferrara, Via Saragat 1, 44122 Ferrara (Italy)

    2014-09-15

    Highlights: • Bronze bowl from Iran belonging to a private collection. • Style and manufacturing consistent with the Achaemenid art (I century B.C.). • Modified Type I patinas. • Apparently continuous tenorite layer at the metal surface on the internal bowl side. • Fragmentation attributed to a severe intergranular attack. - Abstract: A bronze bowl belonging to a private collection, stylistically consistent with the Achaemenid art was investigated to determine the cause of the artwork local fragmentation. The corrosion products were characterised by energy dispersive X-ray fluorescence spectrometry (EDXRF), Raman spectroscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The last technique was also used to determine the chemical composition of the alloy. The metallographic analysis showed that the bowl was obtained from a monophasic bronze alloy, containing about 11% tin and other elements in traces. The presence of an inhomogeneous microstructure with both thermal twin bands and slip lines was consistent with multiple hammering steps followed by partial annealing treatments. On the bowl a very limited chloride contamination was observed and chlorides were never detected in proximity to the metal. These findings and the morphological/compositional characteristics of the patinas permitted to classify that on the internal side of the bowl as a modified Type I morphology, while the patina on the external side of the bowl was less compact, so that it was judged borderline between a “noble” patina and a disfiguring one. On this side, a significant intergranular attack was found, reputed responsible for the fragmentation occurred.

  1. Electrolytic surface hardening of steel,castiron and aluminium-bronze

    Directory of Open Access Journals (Sweden)

    Suhas Keshav Paknik a r

    2006-08-01

    Full Text Available Electrolytic hardening process w as developed in USSR in the 1950s. The process w as developed but w as not com m ercially exploited. There is no evidence of w ork done on this process in India. The author has done this originalw ork applied to different m aterials like steel, castiron and alum inum -bronze.This paper gives details ofm icrostructuraltransform ations along w ith hardness value achieved. There is vitalscope for this process to becom e viable for surfacehardening and selective hardening ofsm allcom ponents.

  2. THE EFFECTS OF PERFORMANCE CHARACTERISTICS TO THE COEFFICIENT OF FRICTION IN SINTERED BRONZE BEARINGS

    Directory of Open Access Journals (Sweden)

    Gültekin KARADERE

    2001-01-01

    Full Text Available In this study, the effects of performance characteristics of self-lubricating, sintered bronze journal bearings to the coefficient of friction is investigated via an experimental test rig. In the experiments, the variation of the coefficient of friction for different velocities and pressures has been investigated for the cases in which an additional oil mass is fed and not fed into the bearing. Furthermore, in the cases where the other parameters are kept constant, the effects of velocity, pressure and temperature to the coefficient of friction are separately investigated, and the results are plotted.

  3. The Chalcolithic and the Bronze Age in the river Neiva Basin, NW of Portugal

    OpenAIRE

    Magalhães, Marisa Cardoso

    2016-01-01

    Relatório de estágio de mestrado em Arqueologia O presente relatório deseja expor os resultados da investigação sobre o Calcolítico e a Idade do Bronze da bacia do Neiva, desenvolvida durante o segundo ano de Mestrado em Arqueologia na Universidade do Minho. Relativamente a estes períodos cronológicos podemos destacar a diversidade de estratégias de povoamento, com tendências para ocupações de locais de menor altitude e mais próximas de vales. Estas comunidades que se estabelec...

  4. Synthesis and structure of a quadratic oxygen bronze containing uranium of valence six

    International Nuclear Information System (INIS)

    (Nb7.6U2.4)(Ba5.2K0.8)O30 is a quadratic bronze with space group P4bm and lattice parameters a = 12.608(5) and c = 4.012(2) A, Z=1. The structure of a single crystal was refined to R = 0.056 (RW = 0.072) for 967 independent reflections with I ≥ 3σI. The U6+ ion is located inside octahedral sites with Nb5+ and Nb4+. (orig.)

  5. THE PALEODEMOGRAPHIC PATTERN OF OYLUM HOYUK POPULATION (THE MIDDLE BRONZE AGE, KİLİS)

    OpenAIRE

    Ayşen Açıkkol Yıldırım

    2013-01-01

    In this study skeleton remaining of 72 individuals excavated from Middle Bronze Age layers of Oylum Höyük (mound) situated in Kilis province, were studied. Sex and age of skeletons, unearthed between 2007-2012, were determined and life tables of the population were formed. Mortality of infants and children of Oylum population was very high. Death rates were determined as 36.6 % for 0-5 years of age group, 57.75 % for 0-15 years of age group. 34.62 % of infants and children from 0-5 years of a...

  6. ARCHAEOMETALLURGICAL STUDIES OF SPEAR HEADS AND ARROW HEADS OF THE MIDDLE BRONZE AGE SITES OF AZERBAIJAN

    OpenAIRE

    Hasanova, Aziza

    2015-01-01

    Quantitative spectroscopy analysis of spear heads and arrow heads of Middle Bronze Age sites of Azerbaijan (second part of the III to the middle of the II millennium BC) has been made to determine the type of the alloy taking into account the accepted limits of natural impurity in metals ( - 0.5% and more). The analyses have shown that copper is the basic materials in all of them. Metallurgical classification the results of sixteen analysis spear heads have shown three of them made of arsenic...

  7. Compositional analyses of a Reutlingen Bronze Age sword discovered at Giurgiu, Romania

    CERN Document Server

    Olariu, A; Avram, A; Badica, T; Olariu, Agata; Alexandrescu, Emilian; Avram, Alexandru; Badica, Teodor

    2003-01-01

    The compositional scheme of a Bronze Age sword, found near the town of Giurgiu in Romania has been determined by the method of particle-induced X-ray emission (PIXE), at the tandem accelerator of the National Institute for Physics and Nuclear Engineering from Bucharest, Magurele, Romania. The results of the analyses and the comparison with the composition of other swords from the same geographic area, the Danubian plane from Bulgaria and Transylvania regions, show that the sword from Giurgiu could be relatively associated with the swords from Bulgaria, having also the same stylistic, temporal and geographical similitude.

  8. Enhanced toughness and stable crack propagation in a novel tungsten fibre-reinforced tungsten composite produced by chemical vapour infiltration

    Science.gov (United States)

    Riesch, J.; Höschen, T.; Linsmeier, Ch; Wurster, S.; You, J.-H.

    2014-04-01

    Tungsten is a promising candidate for the plasma-facing components of a future fusion reactor, but its use is strongly restricted by its inherent brittleness. An innovative concept to overcome this problem is tungsten fibre-reinforced tungsten composite. In this paper we present the first mechanical test of such a composite material using a sample containing multiple fibres. The in situ fracture experiment was performed in a scanning electron microscope for close observation of the propagating crack. Stable crack propagation accompanied with rising load bearing capacity is observed. The fracture toughness is estimated using the test results and the surface observation.

  9. Erosion/corrosion of machinable Tungsten in water

    International Nuclear Information System (INIS)

    It was recently discovered that significant erosion/corrosion occurs with machinable tungsten when exposed to water, particularly when the water has dissolved oxygen present. The problem was first discovered about 1 1/2 years ago when extensive corrosion was found inside the cooling channels of the L5-80 white-beam slits located in sector 3-ID-A. Figure 1 and Figure 2 show cut-away sections of the tungsten slit; the water passages are severely corroded from the cooling water used to cool the slit. The problem was brought to the attention of the world's two largest manufacturers of machinable tungsten, Mi-Tech Metals from Indianapolis, IN and Kulite Tungsten Corp. from East Rutherford, NJ. Neither company had any experience with this problem and were unaware that water could cause such significant corrosion, apparently the APS was the first customer to ever use the material in this fashion

  10. Tungsten alloy research at the US Army Materials Technology Laboratory

    International Nuclear Information System (INIS)

    This paper reports that recent research into tungsten heavy alloys at the U. S. Army Materials Technology Laboratory (MTL) has explored many areas of processing and process development. The recrystallization and respheroidization of tungsten grains in a heavily cold worked heavy alloy has been examined and resulted in the identification of a method of grain refinement. Another area of investigation has been lightly cold worked. It was determined that it was possible to increase the strength and hardness of the tungsten grains by proper hat treatment. MTL has been involved in the Army's small business innovative research (SBIR) program and several programs have been funded. Included among these are a method of coating the tungsten powders with the alloying elements and the development of techniques of powder injection molding of heavy alloys

  11. Underwater explosive welding of thin tungsten foils and copper

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, P., E-mail: manikandan_exp@yahoo.com [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Lee, J.O.; Mizumachi, K. [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Mori, A. [Department of Mechanical Engineering, Sojo University, 4-22-1 Ikeda, Kumamoto 860-0082 (Japan); Raghukandan, K. [Department of Manufacturing Engineering, Annamalai University, Annamalainagar, Cuddalore District, Tamilnadu 608 002 (India); Hokamoto, K. [Shock Wave and Condensed Matter Research Center, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan)

    2011-11-15

    Highlights: > Underwater explosive welding was used to clad tungsten and copper. > The preset inclination was varied and the microstructure was observed. > Microstructure reveals a clear wavy interface for higher preset inclination. > High pressure and high strain rate leads to plastic flow of tungsten. - Abstract: This study demonstrates the ability to clad pure tungsten foils on copper plate using underwater shock waves generated by the detonation of explosive. Microstructural characterization revealed that a higher preset inclination results in wavy morphology. Weld formed at lower inclination exhibit a planar interfacial layer comprising fine grained particles of both components. The plastic flow of tungsten is ascribed to the synergistic influence of high pressure and high strain rate at the collision point.

  12. Computer-controlled preparation of thin tungsten layers

    International Nuclear Information System (INIS)

    Tungsten layers of 1-6 mg/cm2 with diameters of 10 mm are needed as heavy-ion targets and as flat or domed windows for in-beam ion sources. They are prepared by a high-vacuum evaporation-deposition process carried out in a computer-controlled apparatus. The tungsten, placed in the water-cooled crucible of an electron-beam gun, is gradually heated and evaporates at about its melting point (Tm=3643 K). The tungsten is deposited onto 9 mg/cm2 copper backings which are preheated by the thermal radiation from the evaporant. The deposition rate is controlled by a quartz crystal monitor. After the high-vacuum deposition process, the copper backings are removed by selective etching and the self-supported tungsten foils are characterized by their areal mass. The features of the commercially available evaporation unit used are discussed by way of this deposition process. (orig.)

  13. TIG (Tungsten Inert Gas) welding; Le soudage TIG

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-09-15

    After having recalled the Tungsten Inert Gas process principle and the different alternative TIG processes, the author explains the advantages and limits of this process. The applications and recent developments are given. (O.M.)

  14. Use of tungsten coating on iter plasma facing components

    International Nuclear Information System (INIS)

    As part of the US ITER research and development activities, approaches to applying tungsten clads to copper, along with the development of a transpiration-cooled tungsten for use as a disruption energy dump, are being investigated. Joining is being attempted by diffusion bonding using nickel or titanium interlayers. Reduction in bondline residual stresses is being accomplished by use of functionally graded layers of tungsten and copper with copper as the continuous phase. Layers are being fabricated using vacuum plasma spray, liquid phase sintering and powder hot isostatic pressing. Initial metallographic results are promising, with fabrication of tensile and high heat flux specimens planned. Direct infiltration of 74% dense tungsten with magnesium and lithium is planned. (orig.)

  15. 夏商周青铜器铅同位素示踪研究数据库的构建%A Lead Isotope Ratio Data Base of Ancient Chinese Bronzes

    Institute of Scientific and Technical Information of China (English)

    金正耀

    2005-01-01

    A data base of lead isotope ratio of ancient Chinese bronzes is set up. There are 2 888 members, including bronze objects, casting remains, and related ores, etc. in the file. The file contents of data base are made from analysis work on Chinese bronze previously carried out in several laboratories in China, Japan and USA. The main body of the file contents is formed from records, analysis data, reference documents, and images. The data base is designed for sharing information in provenance study on raw metal material for bronze production in China Bronze Age.

  16. Factors affecting the deformation of tungsten (a literature survey)

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, R.L.

    1978-08-25

    Background information relative to wrought tungsten forming was required in support of development studies. Seven principal areas of tungsten metallurgy were of interest: fabrication methods, delamination, recrystallization, heat treatment, fracture characteristics, impurity effects, and surface treatments. Pertinent information in Metal Abstracts from 1967 to mid 1977 was summarized for each area. Only a few papers were reviewed in their entirety; the great majority of information was derived from abstracts of the papers. 61 references.

  17. Reaction of tungsten anion clusters with molecular and atomic nitrogen

    OpenAIRE

    Kim, Young Dok; Stolcic, Davor; Fischer, Matthias; Ganteför, Gerd

    2003-01-01

    Ultraviolet photoelectron spectra for WnN-2 (n=1 8) clusters produced by addition of atomic and molecular nitrogen on W anion clusters are presented. Evidence is provided that molecular chemisorption of N2 is more stable than the dissociative one on tungsten anion clusters consisting of eight atoms or less, which is completely different from the results on tungsten bulk surfaces. A general tendency toward molecular chemisorption for small clusters can be explained by reduced charge transfer f...

  18. Recent advances in high density tungsten composite processing

    Energy Technology Data Exchange (ETDEWEB)

    Cytron, S. [Army Armament Research, Development and Engineering Center, Dover, NJ (United States)

    1993-12-31

    Conventional liquid phase sintering has been the mainstay for processing tungsten alloy composites for the past several decades. New application demands being placed on these high density composites has resulted in the emergence of new processing approaches aimed at developing a new generation of high density tungsten composite materials. Recent investigative studies into rapid solidification technology, solid state sintering, mechanical alloying and explosive compaction are reported here to highlight these recent processing trends.

  19. Hydrodynamic Analysis to Process of Hydrostatic Extrusion for Tungsten Alloy

    Institute of Scientific and Technical Information of China (English)

    Fuchi WANG; Zhaohui ZHANG; Shukui LI

    2001-01-01

    The hydrodynamic analysis to the process of the hydrostatic extrusion for tungsten alloy is carried through the hydrodynamic lubrication theory and Reynolds equation in this paper. The critical velocity equation when the hydrodynamic lubrication conditions appear between the surfaces of the work- piece and the die is obtained, and the relationship between the critical velocity and the extrusion parameters is discussed, which build the theoretical bases to the application of the hydrostatic extrusion for tungsten alloy.

  20. First principle study of hydrogen behavior in hexagonal tungsten carbide

    OpenAIRE

    Kong, Xiang-Shan; You, Yu-Wei; Liu, C. S.; Q. F. Fang; Chen, Jun-Ling; Luo, G.-N.

    2010-01-01

    Understanding the behavior of hydrogen in hexagonal tungsten carbide (WC) is of particular interest for fusion reactor design due to the presence of WC in the divertor of fusion reactors. Therefore, we use first-principles calculations to study the hydrogen behavior in WC. The most stable interstitial site for the hydrogen atom is the projection of the octahedral interstitial site on tungsten basal plane, followed by the site near the projection of the octahedral interstitial site on carbon b...

  1. Metallic Tungsten Nanostructures and Highly Nanostructured Thin Films by Deposition of Tungsten Oxide and Subsequent Reduction in a Single Hot-Wire CVD Process

    NARCIS (Netherlands)

    Harks, P.P.R.M.L.; Houweling, Z.S.; de Jong, M.M.; Kuang, Y; Geus, J.W.; Schropp, R.E.I.

    2012-01-01

    The synthesis of metallic tungsten nanostructures and highly nanostructured thin films is presented. Crystalline tungsten oxide nanostructures are deposited on glassy carbon substrates kept at 700 100 8C by oxidizing resistively heated tungsten filaments in an air flow under subatmospheric pressures

  2. RF Breakdown Studies in Tungsten and Copper Structures

    Science.gov (United States)

    Laurent, L.; Adolphsen, C.; Beebe, S.; Döbert, S.; Luhmann, N. C.; Pearson, C.; Rodriguez, J. A.; Scheitrum, G.; Wuensch, W.

    2006-11-01

    This paper reports on experimental results from the SLAC NLC accelerator structure closeout program, and discusses a study that was conducted to improve the smoothness of machined tungsten for use in high gradient structures. At the Next Linear Collider Test Accelerator (NLCTA), an X-band (11.424 GHz) structure was operated at a lower temperature to determine whether this would decrease the low rate of breakdowns that still occur after initial processing. Also, various vacuum venting experiments were performed to determine the impact of air, airborne particulates, and oxidation on the performance of a processed accelerator structure. As part of a more long-range high-gradient structure development program, alternative materials to copper are being explored. The CLIC study group at CERN has conducted several accelerator experiments at 30 GHz with structures that have tungsten and molybdenum iris inserts. SLAC has also tested versions of the CLIC 30 GHz design scaled to 11.424 GHz. The results have prompted a tungsten material study directed at exploring new fabrication processes that would provide a cleaner and smoother tungsten surface topography suitable for high gradient applications. A significantly improved tungsten surface finish resulted from this material study, and a single cell X-band cavity containing noses with such tungsten surfaces will be high power tested soon.

  3. Integrated analytical methodologies for the study of corrosion processes in archaeological bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Alberghina, Maria Francesca; Barraco, Rosita; Brai, Maria; Schillaci, Tiziano, E-mail: tschillaci@unipa.it; Tranchina, Luigi

    2011-02-15

    The investigations on structure and micro-chemical composition of archaeological metal alloys are needed in archaeometry. The aim of this study is devoted both to acquire information about their provenance and production technology, and to improve our understanding about the corrosion processes. In this paper we present the study of the corrosion phenomena of bronze samples, laboratory-made according to binary, ternary and quaternary alloys typical of Roman archaeometallurgical production through an integrated methodology based on the use of non or micro invasive physical techniques. Among the analysed samples, two were artificially aged through burial in the archaeological site of Tharros, along the west coast of Sardinia (Italy). The corrosion products, typical of the bronzes in archaeological sites near the sea, have been characterized by non invasive and micro-destructive measurements. In particular, the corrosion patinas were examined through optical microscopy, scanning electron microscopy and microanalysis, X-ray fluorescence and laser ablation spectroscopy. The use of integrated technologies allowed us to determine both the elemental composition and surface morphology of the patina, highlighting the correlation between patina nature and chemical composition of the burial context. Moreover, data obtained by the laser-induced breakdown spectroscopy along the depth profile on the samples, have yielded information about the stratigraphic layers of corrosion products and their growth. Finally, the depth profiles allowed us to verify both the chemical elements constituting the patina, the metal ions constituting the alloy and the occurrence of migration phenomena from bulk to the surface.

  4. Las Lunas (Yuncler, Toledo. A Bronze Age hoard with metallic materials from the southern Iberian Meseta

    Directory of Open Access Journals (Sweden)

    Urbina Martínez, Dionisio

    2010-06-01

    Full Text Available Here we present the results of the preliminary study carried out on a new group of metallic materials of the Final Bronze Age, recovered at the end of 2008 in the archaeological excavations at the settlement of Las Lunas (Yuncler, Toledo, Spain. Its geographical situation far away from the main zones of distribution of this type of finds, the singularity of the materials, and the evidence of Atlantic and Mediterranean relations make these materials a remarkable sample for the study of the Final Bronze Age in the centre of the Iberian Peninsula.

    Se exponen los resultados del primer estudio realizado sobre un nuevo conjunto de materiales metálicos del Bronce Final recuperado a finales de 2008 en las excavaciones arqueológicas del yacimiento de Las Lunas (Yuncler, Toledo, España. La localización geográfica del hallazgo, lejos de las principales zonas de dispersión conocidas para este tipo de conjuntos, la singularidad de los objetos que integra, y las relaciones atlánticas y mediterráneas que evidencian sus materiales, lo convierten en un ejemplo destacado para el estudio de este período en el centro de la Península Ibérica.

  5. Thermal conductance at millikelvin temperatures of woven ribbon cable with phosphor-bronze clad superconducting wires

    Science.gov (United States)

    Woodcraft, Adam L.; Ventura, Guglielmo; Martelli, Valentina; Holland, Wayne S.

    2010-08-01

    Woven Nomex® ribbon cables made up with superconducting niobium-titanium wire are used at millikelvin temperatures in many large cryogenic instruments. It is important to know how much heat in transmitted down such cables. However, the conductivity of the materials used is not well known. Another problem is that the wires are normally clad with alloys which exhibit some magnetism. This is a potential problem for instruments employing superconducting detectors. A safe non-magnetic alternative to the usual materials is phosphor-bronze clad niobium-titanium wiring. However, there is little experience with such wires. We have therefore measured the conductance of a ribbon cable made up with these wires. The measured values are in good agreement with our predictions, suggesting that the values we have used to model the cable are sufficiently accurate, and could therefore be used to predict the performance of ribbon cables using other cladding materials, so long as the conductivity of the cladding is reasonably well known. As part of our analysis, we consider the likely variation in thermal conductivity values for C51000 phosphor bronze caused by legitimate variations in composition.

  6. Ancient bronze coins from Mediterranean basin: LAMQS potentiality for lead isotopes comparative analysis with former mineral

    Science.gov (United States)

    Torrisi, L.; Italiano, A.; Torrisi, A.

    2016-11-01

    Bronze coins coming from the area of the Mediterranean basin, dated back the II-X Cent. A.D., were analyzed using different physical analytical techniques. Characteristic X-ray fluorescence was used with electrons and photons, in order to investigate the elemental composition of both the surface layers and bulk. Moreover, the quadrupole mass spectrometry coupled to laser ablation (LAMQS technique) in high vacuum was used to analyse typical material compounds from surface contamination. Mass spectrometry, at high resolution and sensitivity, extended up to 300 amu, allowed measuring the 208Pb/206Pb and 207Pb/206Pb isotopic ratios into the coins. Quantitative relative analyses of these isotopic ratios identify the coin composition such as a "fingerprint" depending on the mineral used to extract the lead. Isotopic ratios in coins can be compared to those of the possible minerals used to produce the bronze alloy. A comparison between the measured isotope ratios in the analyzed coins and the literature database, related to the mineral containing Pb as a function of its geological and geophysical extraction mine, is presented. The analysis, restricted to old coins and the mines of the Mediterranean basin, indicates a possible correlation between the coin compositions and the possible geological sites of the extracted mineral.

  7. The bronze shields found at the Ayanis fortress (Van region, Turkey): manufacturing techniques and corrosion phenomena

    Science.gov (United States)

    Ingo, G. M.; Çilingiroğlu, A.; Faraldi, F.; Riccucci, C.; Casaletto, M. P.; Erdem, A.; Batmaz, A.

    2010-09-01

    The manufacturing techniques, chemical composition and corrosion products grown on archaeological bronze shields found during the excavation of the Ayanis fortress (Lake Van region, Eastern Anatolia, Turkey) were studied by means of the combined use of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. The shields are dated back to 673-645 BC and in some cases are decorated with cuneiform inscriptions and ornaments representing various animals, such as lions and bulls. The micro-chemical and structural results show the presence of corrosion products constituted by copper carbonates (azurite and malachite), cuprite and dangerous chlorine-based compounds (nantokite, atacamite, clinoatacamite and paratacamite) due to the Cl-enriched soil of Ayanis. Furthermore, the results show that the bronze shields are coated with a Sn-enriched thin layer, likely due to an intentional tinning process carried out in ancient times to achieve a silver-like finish. Analytical data show an inter-granular corrosion phenomenon that heavily corroded the boundaries of the large equiassic grains inducing mechanical weakness. This latter phenomenon was induced by the repeated cycles of mechanical work and annealing thermal treatments carried out to restore the ductility and malleability of the alloy. Such processing caused the crystallisation and growth of the flattened grains, as well as impurities segregation phenomena along grain boundaries, thus enhancing the inter-granular long-term corrosion.

  8. Neutron activation analysis of Lerna ceramics (Greece) at Early Bronze Age: local production and trade exchanges

    International Nuclear Information System (INIS)

    Neutron activation analysis is a powerful tool for determining the provenance of ancient ceramics. A sophisticated analytical system for gamma-ray spectrometry, designed specifically for the chemical analysis of ceramics by thermal neutron activation, was used to determine the concentrations of twenty elements in samples of ancient pottery. The measurements were made relative to the standard pottery of Perlman and Asaro. The purpose of the work was to study the production of fine pottery at the settlement of Lerna, in the Argolid of Greece, during the Early Bronze Age (third millennium BC). About half of the 50 samples analysed formed the major compositional group, which was attributed to Lerna. It included, besides the majority of the samples from the second phase of the Early Bronze Age (Lerna III), several samples from the third phase (Lerna IV); that is, from levels immediately succeeding the great destruction which marks the end of the Lerna III settlement. A small number of objects forms a second group of local origin and includes 4 of the 5 clay sealings sampled. Among the archaeologically unusual objects, several could be attributed to Lerna, while others were characterized as imports

  9. The atmospheric corrosion of quaternary bronzes: An evaluation of the dissolution rate of the alloying elements

    Science.gov (United States)

    Bernardi, E.; Chiavari, C.; Martini, C.; Morselli, L.

    2008-07-01

    A comparative evaluation of the corrosion behaviour of a G85 bronze in acid rain solutions was performed. As weathering technique, a wet dry device was used to simulate a cyclic exposure to stagnant rain. The weathering solutions were a collected natural rain and an artificial solution reproducing the natural rain. The solutions were periodically monitored as concerns pH and metallic ion concentrations. On the aged specimens, surface studies were performed through OM, SEM and Raman analyses. At the end of weathering tests (40 days), weight loss measurements were carried out. The aim of this work was to examine the reproducibility in laboratory of the corrosive conditions determined by a natural acid rain. The final goal of this research is to investigate the dissolution of a quaternary alloy exposed to acid rains. The results showed slightly different corrosion behaviours as a consequence of the exposure to natural or synthetic rain. Concerning the mechanism of corrosion of G85 bronze, the innovative approach adopted in this study allowed one to point out the contribution of each alloying element to the general corrosion. Actually, while Cu and Pb progressively form insoluble corrosion compounds, Zn continuously dissolves, without forming detectable insoluble products. The absence of dissolved tin is remarkable.

  10. The Pranemuru project and the radiocarbon chronology of the Sardinian Bronze Age

    Directory of Open Access Journals (Sweden)

    Rubinos, Antonio

    2003-12-01

    Full Text Available New C-14 data collected by a Spanish team working in the Sardinian Pranemuru area, allow usthe possibility of revising the C-14 Chronology for the Nuragic Bronze Age and discussing the reliability of some of the dates, as well as the way they have been published, and their matching with the new official chronology for the Sardinian Bronze and Iron Ages, built on Dendro and C14 sequences for the Italian Peninsula.

    La obtención por parte del Proyecto Pranemuru de cerca de una veintena de dataciones radiocarbónicas para una microregión en época nurágica, de las que aquí se recogen discuten catorce, abre la posibilidad de revisar la cronología de la Edad del Bronce en Cerdeña, a la luz de las dataciones recogidas desde los años 90 por Trump (1990 y Tykot (1994 y, más recientemente, por Webster (2001, discutir la validez de las fechas en función de los criterios de recogida de muestra, contexto arqueológico, desviación estándar y forma en que ha sido publicada, así como contrastarla con la cronología propuesta recientemente para la Protohistoria sarda, de acuerdo con la Dendrocronología y Cronología Radiocarbónica para la Italia peninsular (Lo Schiavo 2002.

  11. $Nb_{3}Sn macrostructure, microstructure, and property comparisons for bronze and internal Sn process strands

    CERN Document Server

    Lee, P J; Larbalestier, D C

    2000-01-01

    The variation in irreversibility field, B*(T), with temperature has been measured for Nb/sub 3/Sn superconducting strands manufactured for ITER using vibrating sample and SQUID magnetometers. The high performance strands were developed for both high transport critical current density, J/sub c/, and low hysteresis loss. Despite a wide variety of designs and components, the strands could be split into two distinctive groups, based on the extrapolated irreversibility fields, which lie about 10% lower than the upper critical field. "Bronze-process" strands exhibited consistently higher B*(T) (28 T to 31 T) compared with "internal Sn" process (24 T to 26 T) conductors. The intrinsic critical current density of the superconductor, J/sub c (sc)/, and the specific pinning force of the grain boundaries, Q/sub gb/, were evaluated using the measured J/sub c/, and image analysis of the macro- and micro-structures. A bronze-processed Nb(-Ta)/sub 3 /Sn was found to have a higher J/sub c(sc)/ but lower Q/sub gb/ than Nb/sub...

  12. Tungsten and tungsten alloy powder metallurgy. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    The bibliography contains citations concerning tungsten powder preparation and processing. Studies include sintering, densification, shrinkage, phase analysis, and heat treatment. The physical and mechanical properties of tungsten powder metal products are included. The effects of additives and particle size on the sintering and sintered articles are also described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  13. Tungsten-molybdenum fractionation in estuarine environments

    Science.gov (United States)

    Mohajerin, T. Jade; Helz, George R.; Johannesson, Karen H.

    2016-03-01

    Dissolved tungsten (W) and molybdenum (Mo) concentrations were measured in surface waters and sediment pore waters of Terrebonne Bay, a shallow estuary in the Mississippi River delta, to investigate the biogeochemical processes that fractionate these Group 6 elements relative to one another during transit from weathering to sedimentary environments. Although many of the chemical properties of W and Mo are similar, the two elements behave autonomously, and the fractionation mechanisms are only partly understood. In sulfidic pore waters, dissolved Mo is depleted relative to river water-seawater mixtures, whereas dissolved W is >10-fold enriched. Reductive dissolution of poorly crystalline phases like ferrihydrite, which is a preferential host of W relative to Mo in grain coatings on river-borne particles, can explain the dissolved W enrichment. Dissolved W becomes increasingly enriched as H2S(aq) rises above about 60 μM due to transformation of WO42- to thiotungstates as well as to additional reductive dissolution of phases that host W. In contrast, as rising sulfide transforms MoO42- to thiomolybdates in pore waters, dissolved Mo is suppressed, probably owing to equilibration with an Fe-Mo-S phase. This putative phase appears to control the aqueous ion product, Q = [Fe2+][MoS42-]0.6 [H2S0]0.4/[H+]0.8, at a value of 10-7.78. Concentrations of dissolved W and Mo in pore waters bear no relation to concentrations in surface waters of the same salinity. In surface waters, dissolved Mo is nearly conserved in the estuarine mixing zone. Dissolved W appears also to be conserved except for several cases where W may have been enhanced by exchange with underlying, W-rich pore waters. With increasing salinity, the molar Mo/W ratio rises from about 10 to about 1000 in surface waters whereas it is mostly sediments, whereas the second explains tungsten's proportionately greater sequestration on river-borne particles and its subsequent release to sulfidic pore waters after the

  14. Dialysate sodium and sodium gradient in maintenance hemodialysis: a neglected sodium restriction approach?

    OpenAIRE

    Munoz Mendoza, Jair; Sun, Sumi; Chertow, Glenn M.; Moran, John, (Thesis); Doss, Sheila; Schiller, Brigitte

    2011-01-01

    Background. A higher sodium gradient (dialysate sodium minus pre-dialysis plasma sodium) during hemodialysis (HD) has been associated with sodium loading; however, its role is not well studied. We hypothesized that a sodium dialysate prescription resulting in a higher sodium gradient is associated with increases in interdialytic weight gain (IDWG), blood pressure (BP) and thirst.

  15. Investigation on corrosion stratigraphy and morphology in some Iron Age bronze alloys vessels by OM, XRD and SEM-EDS methods

    Science.gov (United States)

    Oudbashi, Omid; Hasanpour, Ata; Davami, Parviz

    2016-04-01

    The recently study of the corrosion in some bronze artefacts from the Sangtarashan Iron Age site, western Iran, was established to identify corrosion morphology and mechanism in these objects. The corrosion layers in 22 samples were studied by optical microscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy and X-ray diffraction methods. The results showed that a thin corrosion crust has formed on the surface of bronzes with a triple-layer structure, including two internal and one external corrosion layers. The formation of these layers is due to copper leaching from the bronze surface. The internal corrosion part has been a compact, tin-rich corrosion/oxidation product (noble patina) with some evidences from original metallurgical aspects of the bronze as well as a very thin layer beneath the tin-rich layer. External corrosion products have been identified as basic copper carbonates, malachite and azurite. Based on the results, the corrosion morphology in the Sangtarashan Iron Age bronzes is due to long-term burial in an appropriate environment in a moderately corrosive soil. Although it is the first time to investigate Iron Age bronzes from Iran, this corrosion morphology is partially similar to type I corrosion morphology observed in archaeological bronze objects; nevertheless, some deviations are visible in comparison with previously established patterns.

  16. Mechanistic, kinetic, and processing aspects of tungsten chemical mechanical polishing

    Science.gov (United States)

    Stein, David

    This dissertation presents an investigation into tungsten chemical mechanical polishing (CMP). CMP is the industrially predominant unit operation that removes excess tungsten after non-selective chemical vapor deposition (CVD) during sub-micron integrated circuit (IC) manufacture. This work explores the CMP process from process engineering and fundamental mechanistic perspectives. The process engineering study optimized an existing CMP process to address issues of polish pad and wafer carrier life. Polish rates, post-CMP metrology of patterned wafers, electrical test data, and synergy with a thermal endpoint technique were used to determine the optimal process. The oxidation rate of tungsten during CMP is significantly lower than the removal rate under identical conditions. Tungsten polished without inhibition during cathodic potentiostatic control. Hertzian indenter model calculations preclude colloids of the size used in tungsten CMP slurries from indenting the tungsten surface. AFM surface topography maps and TEM images of post-CMP tungsten do not show evidence of plow marks or intergranular fracture. Polish rate is dependent on potassium iodate concentration; process temperature is not. The colloid species significantly affects the polish rate and process temperature. Process temperature is not a predictor of polish rate. A process energy balance indicates that the process temperature is predominantly due to shaft work, and that any heat of reaction evolved during the CMP process is negligible. Friction and adhesion between alumina and tungsten were studied using modified AFM techniques. Friction was constant with potassium iodate concentration, but varied with applied pressure. This corroborates the results from the energy balance. Adhesion between the alumina and the tungsten was proportional to the potassium iodate concentration. A heuristic mechanism, which captures the relationship between polish rate, pressure, velocity, and slurry chemistry, is presented

  17. 3D scanning and printing as conversation tools: an innovative treatment of a vandalized bronze statue, The Thinker by Rodin

    NARCIS (Netherlands)

    T. Beentjes; R. van der Molen

    2011-01-01

    This contribution discusses the innovative treatment of a severely vandalized bronze sculpture, The Thinker by Auguste Rodin, from the Singer Museum in Laren, The Netherlands. Additional aspects of this controversial treatment such as decision making and documentation are also discussed. In 2007 the

  18. Tungsten Oxides for Photocatalysis, Electrochemistry, and Phototherapy.

    Science.gov (United States)

    Huang, Zhen-Feng; Song, Jiajia; Pan, Lun; Zhang, Xiangwen; Wang, Li; Zou, Ji-Jun

    2015-09-23

    The conversion, storage, and utilization of renewable energy have all become more important than ever before as a response to ever-growing energy and environment concerns. The performance of energy-related technologies strongly relies on the structure and property of the material used. The earth-abundant family of tungsten oxides (WOx ≤3 ) receives considerable attention in photocatalysis, electrochemistry, and phototherapy due to their highly tunable structures and unique physicochemical properties. Great breakthroughs have been made in enhancing the optical absorption, charge separation, redox capability, and electrical conductivity of WOx ≤3 through control of the composition, crystal structure, morphology, and construction of composite structures with other materials, which significantly promotes the efficiency of processes and devices based on this material. Herein, the properties and synthesis of WOx ≤3 family are reviewed, and then their energy-related applications are highlighted, including solar-light-driven water splitting, CO2 reduction, and pollutant removal, electrochromism, supercapacitors, lithium batteries, solar and fuel cells, non-volatile memory devices, gas sensors, and cancer therapy, from the aspect of function-oriented structure design and control. PMID:26287959

  19. Anthocyanins facilitate tungsten accumulation in Brassica

    Energy Technology Data Exchange (ETDEWEB)

    Hale, K.L.

    2002-11-01

    Accumulation of molybdenum in Brassica was recently found to be correlated with anthocyanin content, involving the formation of a blue complex. Here the role of anthocyanins in tungsten sequestration was investigated using three species of Brassica: B. rapa (cv. Fast plants), B. juncea (Indian mustard) and B. oleracea (red cabbage). Seedlings of B. rapa and B. juncea turned blue when supplied with colourless tungstate. The blue compound co-localized with anthocyanins in the peripheral cell layers, and the degree of blueness was correlated with anthocyanin content. The direct involvement of anthocyanins in the blue coloration was evident when purified anthocyanins showed a colour change from pink to blue in vitro upon addition of tungstate, over a wide pH range. Anthocyanin production was upregulated 3-fold by W in B. juncea, possibly reflecting a function for anthocyanins in W tolerance or sequestration. The presence of anthocyanins facilitated W accumulation in B. rapa: anthocyanin-containing seedlings accumulated 3-fold more W than an anthocyaninless mutant. There was no correlation between anthocyanin content and W tolerance under these conditions. The nature of the interaction between anthocyanins and tungstate was investigated. X-ray absorption spectroscopy showed no change in the local chemical environment of Wupon uptake of tungstate by the plant; HPLC analysis of purified anthocyanin with or without tungstate showed no peak shift after metal treatment.

  20. Tungsten Oxides for Photocatalysis, Electrochemistry, and Phototherapy.

    Science.gov (United States)

    Huang, Zhen-Feng; Song, Jiajia; Pan, Lun; Zhang, Xiangwen; Wang, Li; Zou, Ji-Jun

    2015-09-23

    The conversion, storage, and utilization of renewable energy have all become more important than ever before as a response to ever-growing energy and environment concerns. The performance of energy-related technologies strongly relies on the structure and property of the material used. The earth-abundant family of tungsten oxides (WOx ≤3 ) receives considerable attention in photocatalysis, electrochemistry, and phototherapy due to their highly tunable structures and unique physicochemical properties. Great breakthroughs have been made in enhancing the optical absorption, charge separation, redox capability, and electrical conductivity of WOx ≤3 through control of the composition, crystal structure, morphology, and construction of composite structures with other materials, which significantly promotes the efficiency of processes and devices based on this material. Herein, the properties and synthesis of WOx ≤3 family are reviewed, and then their energy-related applications are highlighted, including solar-light-driven water splitting, CO2 reduction, and pollutant removal, electrochromism, supercapacitors, lithium batteries, solar and fuel cells, non-volatile memory devices, gas sensors, and cancer therapy, from the aspect of function-oriented structure design and control.

  1. The DAMPE silicon-tungsten tracker

    Science.gov (United States)

    Azzarello, P.; Ambrosi, G.; Asfandiyarov, R.; Bernardini, P.; Bertucci, B.; Bolognini, A.; Cadoux, F.; Caprai, M.; De Mitri, I.; Domenjoz, M.; Dong, Y.; Duranti, M.; Fan, R.; Fusco, P.; Gallo, V.; Gargano, F.; Gong, K.; Guo, D.; Husi, C.; Ionica, M.; La Marra, D.; Loparco, F.; Marsella, G.; Mazziotta, M. N.; Mesa, J.; Nardinocchi, A.; Nicola, L.; Pelleriti, G.; Peng, W.; Pohl, M.; Postolache, V.; Qiao, R.; Surdo, A.; Tykhonov, A.; Vitillo, S.; Wang, H.; Weber, M.; Wu, D.; Wu, X.; Zhang, F.

    2016-09-01

    The DArk Matter Particle Explorer (DAMPE) is a spaceborne astroparticle physics experiment, launched on 17 December 2015. DAMPE will identify possible dark matter signatures by detecting electrons and photons in the 5 GeV-10 TeV energy range. It will also measure the flux of nuclei up to 100 TeV, for the study of the high energy cosmic ray origin and propagation mechanisms. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon-tungsten tracker-converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7 m2. The STK has been extensively tested for space qualification. Also, numerous beam tests at CERN have been done to study particle detection at silicon module level, and at full detector level. After description of the DAMPE payload and its scientific mission, we will describe the STK characteristics and assembly. We will then focus on some results of single ladder performance tests done with particle beams at CERN.

  2. Large scale production of tungsten-188

    International Nuclear Information System (INIS)

    Tungsten-188 is produced in a fission nuclear reactor with double neutron capture on 186W. The authors have explored large scale production yield (100-200 mCi) of 188W from ORNL-High Flux Isotope Reactor (HFIR) and compared this data with the experimental data available from other reactors and the theoretical calculations. The experimental yield of 188W at EOB from the HFIR operating at 85 MWt power and for one cycle irradiation (∼21 days) at the thermal neutron flux of 2x1015, n.s-1 cm-2 is 4 mCi/mg of 186W. This value is lower than the theoretical value by almost a factor of five. However, for one day irradiation at the Brookhaven High Flux Beam Reactor, the yield of 188W is lower than the theoretical value by a factor of two. Factors responsible for these low production yields and the yields of 187W intermediate radionuclide from several targets is discussed

  3. THE RELATIONSHIP BETWEEN EGYPT AND PALESTINE IN THE MIDDLE BRONZE AGE (CA.2000-1550/1500 BCE.)

    Institute of Scientific and Technical Information of China (English)

    GuoDantong

    2004-01-01

    The relationship between Egypt and Palestine during the Bronze Age has been discussed since the 1940s. For the period of the Middle Bronze Age, the problem is both chronological and interpretative. The end of the Middle Bronze Age is fixed by the initial military activities of Dynasty 18 in Palestine around the end of the 16th century BCE. But the dates for the beginning of this period and the transition from one archaeological phase to another are still debated. Lacking a generally accepted solution, the chronology adopted here is that of Dever --- the transition from MB Ⅰ to MB Ⅱ occurred around 1800 BCE,

  4. Use of portable X-ray fluorescence instrument for bulk alloy analysis on low corroded indoor bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Šatović, D., E-mail: dsatovic@alu.hr [Department of Conservation and Restoration, Academy of Fine Arts, Ilica 85, 10000 Zagreb (Croatia); Desnica, V. [Department of Conservation and Restoration, Academy of Fine Arts, Ilica 85, 10000 Zagreb (Croatia); Fazinić, S. [Laboratory for Ion Beam Interactions, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia)

    2013-11-01

    One of the most often used non-destructive methods for elemental analysis when performing field measurements on bronze sculptures is X-ray fluorescence (XRF) analysis based on portable instrumentation. However, when performing routine in-situ XRF analysis on corroded objects obtained results are sometimes considerably influenced by the corrosion surface products. In this work the suitability of portable XRF for bulk analysis of low corroded bronzes, which were initially precisely characterized using sophisticated and reliable laboratory methods, was investigated and some improvements in measuring technique and data processing were given. Artificially corroded bronze samples were analyzed by a portable XRF instrument using the same methodology and procedures as when performing in-situ analysis on real objects. The samples were first investigated using sophisticated complementary laboratory techniques: Scanning Electron Microscopy, Proton-Induced X-ray Emission Spectroscopy and Rutherford Backscattering Spectrometry, in order to gain precise information on the formation of the corrosion product layers and in-depth elemental profile of corrosion layers for different aging parameters. It has been shown that for corrosion layers of up to ca. 25 μm a portable XRF can yield very accurate quantification results. - Highlights: • XRF quantification is very accurate for bronze corrosion layers of up to ca. 25 μm. • Corrosion layer formation on bronze described in two phases. • Corrosion layers precisely characterized using PIXE, RBS and SEM. • Corrosion approximated as CuO for layer thickness calculations via X-ray attenuations • Increasingly lighter corrosion matrix may cause SnLα radiation intensity inversion.

  5. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, D.A.; Herting, D.L.

    1984-09-01

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables.

  6. Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

    International Nuclear Information System (INIS)

    Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

  7. Tungsten Contact and Line Resistance Reduction with Advanced Pulsed Nucleation Layer and Low Resistivity Tungsten Treatment

    Science.gov (United States)

    Chandrashekar, Anand; Chen, Feng; Lin, Jasmine; Humayun, Raashina; Wongsenakhum, Panya; Chang, Sean; Danek, Michal; Itou, Takamasa; Nakayama, Tomoo; Kariya, Atsushi; Kawaguchi, Masazumi; Hizume, Shunichi

    2010-09-01

    This paper describes electrical testing results of new tungsten chemical vapor deposition (CVD-W) process concepts that were developed to address the W contact and bitline scaling issues on 55 nm node devices. Contact resistance (Rc) measurements in complementary metal oxide semiconductor (CMOS) devices indicate that the new CVD-W process for sub-32 nm and beyond - consisting of an advanced pulsed nucleation layer (PNL) combined with low resistivity tungsten (LRW) initiation - produces a 20-30% drop in Rc for diffused NiSi contacts. From cross-sectional bright field and dark field transmission electron microscopy (TEM) analysis, such Rc improvement can be attributed to improved plugfill and larger in-feature W grain size with the advanced PNL+LRW process. More experiments that measured contact resistance for different feature sizes point to favorable Rc scaling with the advanced PNL+LRW process. Finally, 40% improvement in line resistance was observed with this process as tested on 55 nm embedded dynamic random access memory (DRAM) devices, confirming that the advanced PNL+LRW process can be an effective metallization solution for sub-32 nm devices.

  8. Thermophysical properties of sodium

    International Nuclear Information System (INIS)

    Thermophysical properties of sodium for reactor safety studies are presented. Subcooled, superheated and saturated properties are given. A summary of the thermophysical properties is given in tabular form

  9. Contamination by slow diffusers in ion implantation processes: The examples of molybdenum and tungsten

    International Nuclear Information System (INIS)

    A procedure to measure molybdenum and tungsten contamination in implantation processes by DLTS (Deep Level Transient Spectroscopy) is defined and calibrated for the evaluation of molybdenum and tungsten contaminant dose. The obtained calibrations are used to study molybdenum contamination in BF2 implantations and tungsten contamination by sputtering from a previously contaminated wafer holder. In molybdenum-implanted samples, the molybdenum level located 0.3 eV above valence band is revealed only. In tungsten-implanted samples, two levels are revealed. One of these levels is the tungsten-related hole trap located 0.4 eV above valence band. The other level does not correspond to any tungsten-related level, however it is related to the presence of tungsten and to the sample preparation process. The SPV (Surface Photovoltage) measurement sensitivity to tungsten contamination was also tested, and it was found much lower than the DLTS sensitivity, due to the low tungsten diffusivity. This procedure was used to evaluate contamination in implantation processes. In BF2 implantations, in addition to molybdenum, tungsten contamination is found. Molybdenum and tungsten contamination is found in boron implantation too. The tungsten contamination induced by implantation in a previously contaminated implanter was quantified, and the efficiency of arsenic implantation as a decontamination process was tested. Finally, it was shown that TXRF (Total reflection X-ray Fluorescence) is much less sensitive than DLTS for monitoring tungsten contamination

  10. Contamination by slow diffusers in ion implantation processes: The examples of molybdenum and tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Polignano, M.L., E-mail: maria.polignano@st.com [ST Microelectronics, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy); Mica, I., E-mail: isabella.mica@st.com [ST Microelectronics, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy); Barbarossa, F., E-mail: fbarbarossa87@gmail.com [ST Microelectronics, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy); Galbiati, A., E-mail: amos.galbiati@st.com [ST Microelectronics, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy); Grasso, S., E-mail: salvatore.grasso-r2@st.com [ST Microelectronics, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy); Soncini, V., E-mail: vsoncini@micron.com [Micron, via Olivetti, 2, 20864 Agrate Brianza, MB (Italy)

    2015-08-01

    A procedure to measure molybdenum and tungsten contamination in implantation processes by DLTS (Deep Level Transient Spectroscopy) is defined and calibrated for the evaluation of molybdenum and tungsten contaminant dose. The obtained calibrations are used to study molybdenum contamination in BF{sub 2} implantations and tungsten contamination by sputtering from a previously contaminated wafer holder. In molybdenum-implanted samples, the molybdenum level located 0.3 eV above valence band is revealed only. In tungsten-implanted samples, two levels are revealed. One of these levels is the tungsten-related hole trap located 0.4 eV above valence band. The other level does not correspond to any tungsten-related level, however it is related to the presence of tungsten and to the sample preparation process. The SPV (Surface Photovoltage) measurement sensitivity to tungsten contamination was also tested, and it was found much lower than the DLTS sensitivity, due to the low tungsten diffusivity. This procedure was used to evaluate contamination in implantation processes. In BF{sub 2} implantations, in addition to molybdenum, tungsten contamination is found. Molybdenum and tungsten contamination is found in boron implantation too. The tungsten contamination induced by implantation in a previously contaminated implanter was quantified, and the efficiency of arsenic implantation as a decontamination process was tested. Finally, it was shown that TXRF (Total reflection X-ray Fluorescence) is much less sensitive than DLTS for monitoring tungsten contamination.

  11. Processing of ultra fine grained tungsten for using as plasma facing materials

    International Nuclear Information System (INIS)

    Tungsten with ultra fine grain size and containing no liquid-phase sintering aids is considered as promising candidate materials for plasma facing components using in fusion experimental reactor because of its many favorable properties. Due to the high melting point of tungsten, it is not easy to fabricate tungsten with very high density and retaining fine-grain size. This has been the motivation for exploring new processing techniques for ultra fine grained tungsten. In the author's laboratory, Resistance Sintering under Ultra High Pressure (RSUHP) has been developed to fabricate bulk tungsten with ultra fine grain size without any sintering additive added, and Atmosphere Plasma Spraying (APS) is used to fabricate tungsten coating with ultra fine grain size. It is found that when the initial powder size of tungsten is larger than 1 μm, the relative density of sintered product is more than 97%. For sub-micron sized tungsten powder, the relative density of sintered product is more than 92%, and the porosity of fabricated tungsten coating by APS is less than 10%. The microstructures observation shows that the grain size of both sintered tungsten and tungsten coating is nearly same to the initial powder size. Primary mechanical and thermal shock resistance properties test show that the ultra fine grained tungsten has better performance than traditional tungsten. (authors)

  12. Settlement and landscape history of the Northern Franconian Jura during the Bronze and Iron Ages

    Science.gov (United States)

    Kothieringer, Katja; Lambers, Karsten; Seregély, Timo; Schäfer, Andreas

    2014-05-01

    This paper describes the results of initial archaeological and geoarchaeological fieldwork in the Northern Franconian Jura between the cities of Bayreuth and Bamberg. Our research aims at the reconstruction of settlement patterns and strategies of land use during the Metal Ages (Bronze Age and Iron Age) in the catchment area of the river Weismain. The project is designed as a case study for research into the settlement and landscape history of a rural region of the Central German Uplands during the last two millennia before our era. During the Bronze Age and Iron Age (about 2.100 BC to 30 BC), the Northern Franconian Jura must have been densely populated, as evidenced by numerous burial monuments, prominent hillforts like the Staffelberg, and ritual places on the Jurassic plateau. However, little is known about small rural settlements and hamlets which would have accounted for most of the settlement activity in the region. Thus, we lack the most important element for understanding the cultural history and development of the region as well as the consequences of human impact on the landscape. This impact must have induced changes in vegetation and subsequent erosion processes, leading to the formation of geoarchives like colluvial layers. During our initial fieldwork we identified such colluvial layers in depressions on the Jurassic plateau or at footslope positions. As radiocarbon datings of charcoal fragments showed, some of them date from the Metal Ages. The type is wood of these charcoal fragments is oak, which recently only occurs sporadically in mixed forests with beeches. The quantification of the shift of sediments from the plateau to the valleys will be the next important step of geoarchaeological research. Thus, investigations both on the plateau and in the river valleys will accompany archaeological survey. Apart from landscape reconstruction, they will also provide information on the state of preservation and the conditions for identifying archaeological

  13. GPR Surveys for Archaeological Investigation in a Bronze Age site from NW Portugal

    Science.gov (United States)

    Gonçalves, L.; Sampaio, H. A.; Bettencourt, A. M. S.; Alves, M. I. C.

    2012-04-01

    This work describes the use of Ground-penetrating Radar (GPR) surveys in the identification and mapping of subtle cultural remains, from Pego Late Bronze Age settlement, located near the city of Braga, in NW Portugal. Bronze Age settlements from NW Portugal are characterized by the presence archaeological structures such as storage pits, postholes and trenches. These subtle structures have a very low dielectric contrast, making them quite difficult to detect in GPR surveys. In the case of Pego Site, previous investigations using conventional archaeological techniques, during a rescue excavation, partially revealed a residential area, a necropolis, and a stockade foundation trench that encircle the whole settlement. Different GPR prospection approaches were performed using GSSI Sir 3000 System, with 400 MHz antennae, with the objective of identify and define the borders between the different areas of human occupation inside the settlement. For the GPR survey, a grid-based approach with closely spaced parallels transects was defined, covering different areas inside the site. A first survey was conducted with a pseudo-3D methodology, with 50 cm profile separation, followed by a second survey with a dense data acquisition methodology, with 10 cm profile separation. Processed two-dimensional GPR profiles and constructed amplituded-slice maps were produced and analysed. Wave velocities were determined by reflected wave methods and by Hyperbola-Fitting method. The background analysis of the archaeological and geological features of the site, integrated with the preliminary interpretation of GPR data (profiles and amplitude slice-maps) suggest the presence of flat graves, in the west part of the site, and storage pits, post holes and some small trenches, in the centre and north area of the settlement. This interpretation indicates that the settlement is individualized in two different areas, a necropolis and a residential area, such as the first archaeological study

  14. Armorican arrowhead biographies: Production and function of an Early Bronze Age prestige good from Brittany (France

    Directory of Open Access Journals (Sweden)

    Clément Nicolas

    2014-09-01

    Full Text Available Brittany can pride itself on the Armorican arrowheads found in Early Bronze Age graves (2150-1700 BC. In the present state of knowledge, these are the only specialized craft products in knapped flint produced in this region at the western edge of continental Europe. Admired since the 19th century, these flint arrowheads have never really been studied. Due to the wealth of graves and grave-goods, a relatively precise study can be undertaken of the development of these craft products, despite the low number of reliable radiocarbon dates.These arrowheads are characterized by a well-defined type (pointed tang and oblique barbs most often combined with ogival form. Raw materials show the selection of a high quality yellow translucent flint, of which the origin has to be sought at more than 400 kilometers (Lower Turonian flint from Cher Valley. From a technical point of view, Armorican arrowheads reveal a great mastery of retouch by pressure-flaking. This skill is written in stone by the perfection of forms, the extreme thinness (until 2,5 mm thick and very long barbs (until 25 mm long. Such work could not have been done without the use of copper, even bronze, awls. Moreover, some marks may testify to the implication of these tools. On 549 arrowheads that have reached to us, none of them presents diagnostical impact features. However, use-wear analysis indicates that most of them were hafted (adhesive traces, bright spots, blunt edges. These facts suggest that they are less functional arrowheads than objects for the show. In the graves, Armorican arrowheads are frequently set down carefully in wooden boxes taking the shaft off.The Armorican arrowheads with their exotic raw materials, their high-degree of technicality, and their absence of use, have all features of a prestige good. They have been discovered by dozens in few graves under barrows with very rich funeral items (bronze daggers decorated with golden pins, precious bracers, silver beakers

  15. Earthquake and the Catastrophic End of the Late Bronze Age in the Eastern Mediterranean

    Science.gov (United States)

    Nur, A.

    2009-04-01

    The reasons for the catastrophic and wide spread political as well as physical collapse in the Aegean and Eastern Mediterranean areas that define the end of the Bronze age ca. 1225 BC to 1175 BC remain a major enigma. It has been attributed by historian to attacks by outsiders with the most favored group being the (enigmatic) so-called sea people. Unfortunately there is no real evidence for this. However combined geological, geophysical and archaeological evidence suggests that earthquakes may have played a key role in this extraordinary collapse during the late 13th and early 12th centuries . Based on the instrumentally recorded earthquakes occurring in the Aegean and Eastern Mediterranean region during the 20th century, several events that have clear historical information, and the geography of seismically active faults it is obvious that numerous earthquakes of magnitude 6·5 or greater (enough to destroy modern buildings, let alone those of antiquity) occurred here frequently in the past. Furthermore major earthquakes often occur in this region in groups, known as ‘‘sequences'' or ‘‘storms'', in which one large quake is followed days, months, or a few years later by others elsewhere on the plate boundary fault lines. When a map of the areas in the Aegean and Eastern Mediterranean region shaken by 20th century  earthquakes of magnitude 6·5 and greater and with an intensity of VII or greater is overlaid on Robert Drews' map of sites destroyed in these same regions during the so-called ‘‘Catastrophe'' near the end of the Late Bronze Age, it is readily apparent that virtually all of these LBA sites lie within the affected (‘‘high-shaking'') areas. This would suggest that a major ‘‘earthquake storm'' may have occurred in the Late Bronze Age Aegean and Eastern Mediterranean during the years 1225-1175 . This ‘‘storm'' may have interacted with societal, political and economic forces at work in these areas c. 1200  and

  16. Crystallographic conditions for the initiation of cavitation erosion in CuMn11Al11 bronze

    Directory of Open Access Journals (Sweden)

    D. Zasada

    2008-09-01

    Full Text Available Purpose: The basic aim of this paper is to examine and present specific destruction processes connected with cavitation erosion of multi-component Cu-Mn-Al bronzes. In technical operational conditions these processes are ‘masked’ by the effects of electrochemical corrosion phenomena. However, these destructive processes may significantly accelerate the destruction of flow devices and marine propulsion systems. The essential phenomena occurring during these processes are incubation and propagation of brittle cracks in the planes of cleavage planes of the ordered phase β (Cu3Mn2Al that occurs in the examined group of alloys. Additional purpose is the assessment of possible applications of alloys with single-phase structure of intermetallic phases as model materials for research into erosion-cavitation resistance.Design/methodology/approach: This work presents research results concerning erosion cavitation resistance of a model alloy examined at a cavitation jet stand. The destructed areas were examined by gravimetric methods and those using scanning microscopy combined with computer image analysis. As the test materials used were single phase model alloys with the composition simulating selected phase components of Cu-Mn-Al bronzes, it was possible to examine erosion cavitation phenomena in the conditions of minimized effect of electrochemical phenomena.Findings: It has been found that at the initial period of destruction of the phase β in multi-component Mn-Al bronzes the prevailing form of destruction was a classical attack along grain boundaries, starting from the grain boundary junctions while in cases where the Cu3Mn2Al superstructure was present, the major mechanism of the incubation of erosion cavitation damage in the phase β is brittle cracking along cleavage planes {001} oriented at 45° angle to the exposed surface.Research limitations/implications: An essential problem is the verification of the results obtained using the

  17. Measurements and modelling of hydrogen dynamics in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Johannes [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany); Technische Universitaet Muenchen, James-Franck-Str. 1, D-85748 Garching (Germany); Schwarz-Selinger, Thomas; Schmid, Klaus; Toussaint, Udo von; Jacob, Wolfgang [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

    2015-05-01

    Although hydrogen retention in defect free tungsten is low it can be significantly altered by plasma wetting. Thus understanding the interaction and dynamics of hydrogen in tungsten becomes an important issue. Present understanding distinguishes between solute and trapped hydrogen inventory. The solute hydrogen is located in the tetrahedral interstitial sites of bbc tungsten and can diffuse rapidly due to the low activation energy of 0.2-0.4 eV. The trapped hydrogen inventory resides at defects like vacancies, grain boundaries or dislocations, with de-trapping energies between 0.8-2.0 eV and is therefore less mobile. Common ex-situ experiments only allow the investigation of hydrogen retained in traps, while the solute is out of experimental reach due to its fast out-gassing at ambient temperatures. In this study the dynamics of the solute hydrogen in tungsten is measured in-situ for the first time. Diffusion/trapping simulations reveal that for low temperature e.g. 200 K, the solute hydrogen dominates the total inventory and its out-gassing after implantation is slowed down to the timescale of hours. Therefore in-situ hydrogen implantation and nuclear reaction analysis of tungsten samples are conducted at temperatures down to 140 K investigating experimentally the dynamics of solute hydrogen.

  18. Accelerated Molecular Dynamics studies of He Bubble Growth in Tungsten

    Science.gov (United States)

    Uberuaga, Blas; Sandoval, Luis; Perez, Danny; Voter, Arthur

    2015-11-01

    Understanding how materials respond to extreme environments is critical for predicting and improving performance. In materials such as tungsten exposed to plasmas for nuclear fusion applications, novel nanoscale fuzzes, comprised of tendrils of tungsten, form as a consequence of the implantation of He into the near surface. However, the detailed mechanisms that link He bubble formation to the ultimate development of fuzz are unclear. Molecular dynamics simulations provide insight into the He implantation process, but are necessarily performed at implantation rates that are orders of magnitudes faster than experiment. Here, using accelerated molecular dynamics methods, we examine the role of He implantation rates on the physical evolution of He bubbles in tungsten. We find that, as the He rate is reduced, new types of events involving the response of the tungsten matrix to the pressure in the bubble become competitive and change the overall evolution of the bubble as well as the subsequent morphology of the tungsten surface. We have also examined how bubble growth differs at various microstructural features. These results highlight the importance of performing simulations at experimentally relevant conditions in order to correctly capture the contributions of the various significant kinetic processes and predict the overall response of the material.

  19. Mechanical-property evaluation of a series of commercial tungsten alloys. Memorandum report

    Energy Technology Data Exchange (ETDEWEB)

    Bruchey, W.J.; Montiel, D.M.

    1987-06-01

    A series of commercially available tungsten alloys ranging in tungsten content from 75% to 95% were evaluated. Typical tensile and compressive engineering properties are reported. These tests were conducted in support of penetrator ballistic-test programs.

  20. 75 FR 75694 - Certain Semiconductor Integration Circuits Using Tungsten Metallization and Products Containing...

    Science.gov (United States)

    2010-12-06

    ... COMMISSION Certain Semiconductor Integration Circuits Using Tungsten Metallization and Products Containing... United States after importation of certain semiconductor integrated circuits using tungsten metallization... following six respondents ] remained in the investigation: Tower Semiconductor, Ltd. of Israel;...

  1. Influence of precipitate size and morphology on grain refinement in nickel aluminium bronze

    Science.gov (United States)

    Barr, C. J.; Xia, K.

    2015-08-01

    Nickel aluminium bronze (NAB) was subjected to equal channel angular pressing (ECAP) using routes BA and C at 400°C to investigate the effect of precipitate size and morphology on grain refinement in low stacking fault energy alloys. Both routes produced dynamically recrystallised grains of ∼550 nm in size although only route BA was able to create a uniform distribution of the refined grains. The large unrefined regions in NAB processed via route C was thought to arise from its inability to redistribute the various precipitate phases, as recrystallisation was enhanced around the coarse κII rosettes and refined κIII lamellae but reduced in the areas containing fine κIV precipitates.

  2. Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous chloride solution

    Indian Academy of Sciences (India)

    N Saoudi; A Bellaouchou; A Guenbour; A Ben Bachir; E M Essassi; M El Achouri

    2010-06-01

    A new corrosion inhibitor, viz. 3-ethyl-6-méthyl-quinoxalin-2-one, 1-benzyl-6-methyl-quinoxalin- 2-one, 2-benzyloxy-3,6-dimethyl-quinoxaline, 1-benzyl-3-methyl-quinoxalin-2-one, were synthesized in the laboratory. Their influence on the inhibition on corrosion of bronze in aqueous chloride solution (3% NaCl) was studied by electrochemical polarization methods and weight-loss measurements. The impact of temperature on the effectiveness of the substances mentioned above has been determined between 20 and 60°C. The results showed that the corrosion resistance was greatly enhanced in the presence of inhibitor and that the effectiveness depends on some physicochemical properties of the molecule, related to its functional groups. These compounds act through the formation of a protective film on the surface of the alloy.

  3. Paysages funéraires de l’âge du Bronze

    OpenAIRE

    Gomez de  Soto, José

    2015-01-01

    Du 15 au 18 octobre 2008 s’est tenu au musée de Herne en Westphalie un colloque international intitulé « Gräberlandschaften der Bronzezeit. Paysages funéraires de l’âge du Bronze ». Cette manifestation s’insère dans une succession de colloques bi-annuels inaugurée par celui sur le RSFO tenu à Nemours en 1986. Les actes, qui viennent de paraître, réunissent trente-sept contributions, rédigées en allemand, en français ou en anglais. Les résumés, donnés dans les trois langues, permettront à ceux...

  4. Performance evaluation of grid-enabled registration algorithms using bronze-standards

    CERN Document Server

    Glatard, T; Montagnat, J

    2006-01-01

    Evaluating registration algorithms is difficult due to the lack of gold standard in most clinical procedures. The bronze standard is a real-data based statistical method providing an alternative registration reference through a computationally intensive image database registration procedure. We propose in this paper an efficient implementation of this method through a grid-interfaced workflow enactor enabling the concurrent processing of hundreds of image registrations in a couple of hours only. The performances of two different grid infrastructures were compared. We computed the accuracy of 4 different rigid registration algorithms on longitudinal MRI images of brain tumors. Results showed an average subvoxel accuracy of 0.4 mm and 0.15 degrees in rotation.

  5. Strengthening Mechanisms in NiAl Bronze: Hot Deformation by Rolling and Friction-Stir Processing

    Science.gov (United States)

    Menon, Sarath K.; Pierce, Frank A.; Rosemark, Brian P.; Oh-Ishi, Keiichiro; Swaminathan, Srinivasan; McNelley, Terry R.

    2012-10-01

    Microstructures produced by isothermal hot rolling of a NiAl bronze material were evaluated by quantitative microscopy methods and parameters describing the contributions of precipitate dispersions, grain size, solute content, and dislocation density to the yield strengths of the individual constituents of microstructure were determined. Models for the strengths of the individual constituents were combined to predict the temperature dependence of the yield strength as a function of hot rolling temperature, and the prediction was found to be in good agreement with measured yield strengths. The models were applied to microstructures in a stir zone produced by multipass friction-stir processing (FSP) and, again, found to predict measured yield strengths with high accuracy. Such models may aid in assessing the role of microstructure gradients produced during FSP and other processes.

  6. Silvery hair with bronze-tan in a child: A case of Elejalde disease

    Directory of Open Access Journals (Sweden)

    Inamadar Arun

    2007-01-01

    Full Text Available A 5-year-old boy was admitted for severe neurological impairment including hypotonia and loss of consciousness without preceding febrile illness. On examination, he had silver colored hair and bronze-tan over photo-exposed body parts. He was born of consanguineous parents and three of his elder siblings, who died in early childhood, had similar colored hair. Complete blood count and serum immunoglobulin levels were within normal limits. Peripheral blood smear did not show any cytoplasmic granules in neutrophils. Cerebro-spinal fluid examination did not reveal any abnormality. Light microscopic examination of the hair revealed irregular clumping of the melanin throughout the shafts. The patient died on the second day following admission. A clinical diagnosis of Elejalde disease was made. The clinical and genetic overlapping of the three silvery-hair syndromes has been discussed.

  7. Influence of heat treatment on tribological behaviors of novel wrought aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    张卫文; 倪东惠; 夏伟; 邱诚; 陈维平

    2002-01-01

    Influence of heat treatment on mechanica l properties and tribologica l behaviors of Ti and B modified wrought aluminum bronze were studied. The res ults show that different strength and plasticity combination of the alloy after solu tion treatment can be obtained by adjusting the ageing temperature. When aged at 45 0 ℃, the tensile strength σb, yield strength σ0.2, elongatio n δ and hardness of the alloy are 1 050 MPa, 780 MPa, 4.5%, HB282, respectively. When aged at 650 ℃, those of the alloy are 905 MPa, 600 MPa, 12%, HB232, respectively. Under boundary l ubri cation condition with pressure above 22.2 MPa, alloy with low temperature agei ng has the best wear property. However, under the condition involving impact or sh ock loading, alloy with high temperature ageing is preferable. If the load is no t heavy, the alloy under extrusion state is favorable for wear-resisting parts.

  8. A mineralogical study of Late Bronze Age ceramics from Palatca (Transylvania, Romania

    Directory of Open Access Journals (Sweden)

    Lucretia Ghergari

    2012-01-01

    Full Text Available Our paper studies the mineralogical and petrographical characteristics of 28 ceramic fragments that were excavated in the village of Palatca, Transylvania (Romania. Optical microscopy, X-Ray powder diffraction (XRD, scanning electron microscopy (SEM, grain size analyses, and porosity measurements were used to investigate the samples. Our objective was to describe or reconstruct the corresponding products and to elucidate the manufacturing process, the firing techniques, and the transformation pathways. Based on our results, we conclude that the Late Bronze Age ceramics (1600-1300 BC were produced from clay and temper material such as river sand and ceramoclasts. It has been modeled by hand and fired between 800 and 950°C. For most samples, we can narrow the temperature range to 850-900°C. We interpret the data further from a geoarchaeological point of view with respect to the historical evolution of the local culture.

  9. Corrosion atmosphérique des bronzes et Spectroscopie Mössbauer.

    OpenAIRE

    Sougrati, Moulay Tahar

    2008-01-01

    Afin d'améliorer la compréhension de la corrosion atmosphérique des bronzes, nous avons mis en oeuvre : - La caractérisation des composés d'étain, susceptibles d'être formés en corrosion atmosphérique, par une approche multi-analytique, la spectroscopie Mössbauer joue un rôle central (analyse sélective et quantitative). Les paramètres hyperfins et les facteurs Lamb-Mössbauer de plusieurs oxydes, sulfates et chlorures d'étain ont été déterminés. Les facteurs f sont dispersés et dépendants de t...

  10. Analysis of neutron diffraction profiles in bronze archaeological statuettes produced by solid lost wax casting

    Science.gov (United States)

    Giuliani, Alessandra; Fiori, Fabrizio; Gysens, Jacqueline; Manescu, Adrian; Rustichelli, Franco

    2008-03-01

    In the framework of a research aiming to assess the suitability of neutron/x-ray non-destructive techniques for the characterization of archaeological objects, two bronze items were studied by neutron diffraction. The origins of two small statues are, respectively, Egyptian (XXI-XXX Dynasties, c1070-343 B.C.) and Etruscan (IV-III centuries B.C.), belonging to a private collection. By hard x-ray diffraction we previously verified that both statuettes have a coarse microstructure (big grains). From historical considerations we believe that both items were produced by solid lost wax processes of casting. This processing technique does not completely justify the presence of microstrains; as a consequence, due to unexpected neutron diffraction peak broadening, a non-uniform Sn wt% is suspected. In the present work we discuss this deduction by means of Rietveld analysis of the neutron diffraction profiles.

  11. Combining X-ray based methods to study the protohistoric bronze technology in Western Iberia

    Energy Technology Data Exchange (ETDEWEB)

    Valério, P., E-mail: pvalerio@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Silva, R.J.C., E-mail: rjcs@fct.unl.pt [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Soares, A.M.M., E-mail: amsoares@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Araújo, M.F., E-mail: faraujo@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Gonçalves, A.P., E-mail: apg@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Soares, R.M., E-mail: ruigusmao@hotmail.com [UNIARQ, Centro de Arqueologia da Universidade de Lisboa, Faculdade de Letras, Alameda da Universidade, 1600-214 Lisboa (Portugal)

    2015-09-01

    The Phoenician arrival at Iberian coastal regions had an actual influence on indigenous technology. A collection of coeval metallurgical remains and artefacts was studied by EDXRF, micro-EDXRF, SEM–EDS and XRD, to identify certain features of the production and utilisation of metal in protohistoric Western Iberia. The composition of artefacts indicates a prevalence of Cu–Sn alloys with low content of impurities (Pb, As, Sb and Fe) during Late Bronze and Early Iron Ages, while the composition of slags points to a smaller loss of copper in Phoenician smelting operations. Moreover, the amount of iron impurities in metal proved to be a helpful discriminator between indigenous and Phoenician-based metallurgies, showing that later alloys have higher amounts of iron. Besides, the indigenous alloys have higher tin contents that can probably be explained by the easier access to metal sources of local communities.

  12. Towards mineralogical and geochemical reference groups for some Bronze Age ceramics 
from Transylvania (Romania

    Directory of Open Access Journals (Sweden)

    Volker Hoeck

    2009-09-01

    Full Text Available Based on their chemical composition ceramic shards from three Bronze Age sites in Transylvania, i.e., Copăceni, Derşida and Palatca respectively, were distinguished by major, trace, and RE elements. Within the Copăceni samples, two subgroups (A and B showing different chemistry and mineralogy were additionally separated out. The link between chemistry and mineralogy showed clearly the important contribution of the temper to the overall chemistry of the ceramic shards. In turn, the chemistry facilitated the provenance study of the raw materials, which were collected in the vicinity of the sites. In combination with the mineralogy of the ceramics, the chemical analyses can serve as a basis for a geochemical reference set used by further studies.

  13. The inhibition effect and mechanism of L-cysteine on the corrosion of bronze covered with a CuCl patina

    International Nuclear Information System (INIS)

    Highlights: • CuCl patina was synthesized on bronze electrodes with electrochemical method. • L-cysteine was used as a green inhibitor for bronze covered with CuCl patina. • The inhibition efficiency reached above 90%. • The inhibition mechanism of L-cysteine on CuCl patina was investigated. - Abstract: CuCl patina was synthesized on bronze electrodes with electrochemical method. The inhibition effect and mechanism of L-cysteine (Cys) on bronze covered with CuCl patina have been studied with electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques. The EIS results show that Cys stabilized the CuCl patina to a great extent. The hydrolysis reaction of CuCl was inhibited effectively and an inhibition efficiency of over 90% was achieved. The XPS analyses indicate that the chemisorption of Cys molecules on CuCl surface occurred through sulfur atom in thiol and nitrogen atom in amino group

  14. Biological affinities and adaptations of Bronze Age Bactrians: IV. A craniometric investigation of Bactrian origins.

    Science.gov (United States)

    Hemphill, B E

    1999-02-01

    Discovery of a previously unknown Bronze Age civilization (Oxus civilization) centered on the oases of Central Asia revealed the presence of large, preplanned urban centers immediately above sterile soil. Given the absence of local antecedents, the sudden appearance and proliferation of these Oxus civilization urban centers in the oases of Bactria and Margiana immediately raised the issue of where the inhabitants of these urban centers came from. Three hypotheses have been offered by archaeologists to account for the origins of Oxus civilization populations. These include the early influence model, the late colonization model, and the trichotomy model. Eleven craniometric variables from 12 Aeneolithic and Bronze Age samples, encompassing 657 adults from Central Asia, Iran, and the Indus Valley, are compared to test which if any of these hypotheses are supported by the pattern of phenetic affinities possessed by the Oxus civilization inhabitants of the north Bactrian oasis. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (WPGMA, neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results of this analysis provide no support for either the late colonization model or the trichotomy model but do offer some support for the early influence model. Nevertheless, it is clear that the early influence model fails to account for a shift in interregional contacts, perhaps from western China to the north around 2000 BC, that appears to have played a major role in the origins of the Oxus civilization inhabitants of the north Bactrian oasis. PMID:9988380

  15. Comparison of LIBS and {mu}-XRF measurements on bronze alloys for monitoring plasma effects

    Energy Technology Data Exchange (ETDEWEB)

    Alberghina, M F; Barraco, R; Brai, M; Schillaci, T; Tranchina, L, E-mail: tschillaci@unipa.it [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze Ed. 18, 90128 Palermo (Italy)

    2011-01-01

    The laser-induced breakdown spectroscopy (LIBS) technique is often used as atomic spectroscopic technique for elemental analysis of materials. However, it presents some drawbacks that make an accurate quantitative analysis difficult. Since the plasma properties, such as spatial inhomogeneity and plume stoichiometry strongly depend on the experimental conditions, the measurements are less reproducible. In order to evaluate the measurement fluctuations, we propose to use the more established micro X-Ray fluorescence ({mu}-XRF) technique for validating LIBS data. In particular, the quantitative data, obtained by varying the laser fluence, the shot numbers and the temporal acquisition parameters, were compared with those obtained by {mu}-XRF on laboratory made samples of binary, ternary and quaternary bronze alloys. For LIBS measurements a mobile double pulse laser instrument equipped with an high resolution Echelle type monochromator coupled to an intensified CCD camera was used. {mu}-XRF analyses were performed with a portable instrument that uses a micro collimated X-Ray beam and it is equipped with an high resolution detector. The LIBS results show a strong dependence both on the instrumental set up and the chemical-physical properties of the sample. With our findings we could identify the most suitable parameters to be used in the investigation of the different bronze alloys. The possibility to carry out a quantitative analysis by using the LIBS technique was checked through the comparison with related {mu}-XRF data. In particular in this paper we identified a set of reliable LIBS parameters for the quantitative analysis of copper, tin and zinc. Further analyses will be necessary to reach this goal also for the minor constituents as lead.

  16. Late Bronze Age in Alcáçova de Santarém (Portugal

    Directory of Open Access Journals (Sweden)

    Arruda, Ana Margarida

    2015-06-01

    Full Text Available The field work that took place in the restaurant area in Jardim das Portas do Sol (Alcáçova de Santarém recovered well-preserved archaeological layers dated to the Late Bronze Age, lying directly underneath the Iron Age phase. The excavation made it possible to collect an important set of ceramics that incorporate printed and incised decoration, which can be easily decoration related to the Cogotas 1 cultural background. Burnished decorations, with grooves on the inner surface and outer strips, are less common. The formal repertoire does not deviate from what is known about the Late Bronze Age in central and southern Iberian Peninsula. The data allow us to propose a chronology centered in the early 1st millennium BCE for this occupation.Durante los trabajos de campo, realizados en el área del restaurante del Jardim das Portas do Sol, se documentaron, por primera vez en Alcáçova de Santarém, niveles conservados del final de la Edad del Bronce, inmediatamente infrapuestos a los de la Edad del Hierro. Su excavación permitió recoger un conjunto de materiales cerámicos que incorpora varios fragmentos decorados por impresión e incisión, que pueden ser fácilmente relacionados con el universo cultural de Cogotas 1. Las decoraciones bruñidas con surcos en la superficie interna y con franjas al exterior son mucho menos frecuentes. El repertorio formal no difiere del conocido para el Bronce Final del centro y sur de la Península Ibérica. Los datos permiten proponer una cronologia del inicio del 1 milenio a.n.e. (siglo IX para esta ocupación.

  17. Bronze age cosmology and rock art images. Solar ships, deer and charts

    Science.gov (United States)

    Dimitriadis, G.

    Bronze Age societies were technologically complex. The impressive production of metal artefacts embodies clearly their astronomical culture and cosmological viewpoint. Same ascertainment is valid also for rock art. In fact, around the European landscape were discovered several cliffs engraved with solar ships, deer and charts. How one could be interpret them? Which is the hidden mentality? From the end of 3rd millennium-early 2nd millennium B. C. deep technological transformations are made by metals. New inventions such metal extraction for weapon production, horse pulling chariot used for war and the bull pulling one used for trade may shorten the culture and material distances between Central Europe and South Mediterranean area. Indeed, taphonomic studies indicate a specific modification of the human body mortuary traditional disposition (orientated to significant astronomical targets) below a substantial transformation of mortuary apparatus with spot evidence of weapons (halberds, swords, knifes) and ornaments (double spiral, lunar shape pectorals). The famous Trundhold Solar chart, the 2nd millennium terracotta chart form Dupljaja, the solar boats petroglyph in Bohusland and the horse rider carved on Philippi's cliffs were conceived by the same mentality: communion with the divinity. Culture expressions as communicate manifestation attested in rock art were produced by the same mentality presented in Bronze Age art-crafts such as, 1. Culture epidemiologic patterns dispersion took place through out iconographic motives, and, 2. Animals can play a double face function inside an analogical-mythological system: a. animal-reflex; b. animal-agent. The question is: Could such petroglyphs help us to "read" archaeoastronomical properly in an archaeological site?

  18. Archaeological fieldwork in the Bronze Age site of Cerro de la Encina (Monachil, Granada

    Directory of Open Access Journals (Sweden)

    Aranda Jiménez, Gonzalo

    2005-06-01

    Full Text Available New archaeological fieldwork has been carried out from November 2003 to May 2004 in the Bronze Age site of Cerro de la Encina, due to the interest of the regional government of Andalusia in displaying the settlement for visitors. The aim of this fieldwork has been the systematic excavation of a large settlement area partially known thanks to the excavations developed at the beginning of 1980s. A first toccupation period belonging to the Argaric Culture has been documented, highlighting specially the funerary ritual characterized by individual inhumations located below dwellings. After a gap in the occupation of the settlement a new social group belonging to the Late Bronze Age Culture of Southeast of Spain inhabits the Cerro de la Encina.

    El interés de la Consejería de Cultura de la Junta de Andalucía por la musealización del yacimiento del Cerro de la Encina ha motivado el desarrollo de nuevas investigaciones arqueológicas cuya primera fase se ha desarrollado entre Noviembre de 2003 y Mayo de 2004. Los trabajos han consistido en la excavación sistemática de un área de poblado de grandes dimensiones parcialmente conocida por las investigaciones realizadas a principios de los años 80. Los resultados han sido del máximo interés documentándose un primer momento de ocupación perteneciente a la Cultura de El Argar en el que destaca su espectacular registro funerario integrado dentro de las áreas de habitación. Tras un periodo de abandono del yacimiento se produce una nueva ocupación correspondiente a una comunidad del Bronce Final del Sureste.

  19. Annular sodium flowsensor

    International Nuclear Information System (INIS)

    This paper describes a unique eddy-current type liquid sodium flowsensor, designed as a joint effort between Argonne National Laboratory and Kaman Instrumentation Corp. Test results are included for operation of the flowsensor mounted on a sodium test loop whose configuration simulates the actual operating conditions, except for the magnetic field of the ALIP

  20. Visibility in sodium fume

    International Nuclear Information System (INIS)

    The appearance of sodium fume of unknown concentration and the effects of short term exposure on unprotected workers is described. The molecular extinction coefficient of sodium fume is calculated from which light transmission data, and a rapid method for the estimation of the fume concentration is proposed. (author)

  1. Properties of drawn W wire used as high performance fibre in tungsten fibre-reinforced tungsten composite

    Science.gov (United States)

    Riesch, J.; Almanstötter, J.; Coenen, J. W.; Fuhr, M.; Gietl, H.; Han, Y.; Höschen, T.; Linsmeier, Ch; Travitzky, N.; Zhao, P.; Neu, R.

    2016-07-01

    High strength and creep resistance also at high temperature, combined with a high thermal conductivity and high melting point make tungsten (W) an ideal material for highly loaded areas in future fusion reactors. However, as a typical bcc metal tungsten features an intrinsic brittleness up to very high temperature and is prone to operational embrittlement. Tungsten fibre-reinforced tungsten composite (Wf/W) utilizes extrinsic toughening mechanisms similar to ceramic fibre-reinforced ceramics and therefore overcomes the brittleness problem. The properties of the composite are to a large extend determined by the properties of the drawn tungsten wire used as reinforcement fibres. W wire exhibits a superior strength and shows ductile behaviour with exceptional local plasticity. Beside the typical mechanisms observed for ceramic composites the ductile deformation of the fibres is therefore an additional very effective toughening mechanism. Tension tests were used to investigate this phenomenon in more detail. Results show that there is a region of enhanced localized plastic deformation. The specific energy consumption in this region was estimated and used to suggest optimisation options for Wf/W composites.

  2. Tungsten-microdiamond composites for plasma facing components

    Science.gov (United States)

    Livramento, V.; Nunes, D.; Correia, J. B.; Carvalho, P. A.; Mardolcar, U.; Mateus, R.; Hanada, K.; Shohoji, N.; Fernandes, H.; Silva, C.; Alves, E.

    2011-09-01

    Tungsten is considered as one of promising candidate materials for plasma facing component in nuclear fusion reactors due to its resistance to sputtering and high melting point. High thermal conductivity is also a prerequisite for plasma facing components under the unique service environment of fusion reactor characterised by the massive heat load, especially in the divertor area. The feasibility of mechanical alloying of nanodiamond and tungsten, and the consolidation of the composite powders with Spark Plasma Sintering (SPS) was previously demonstrated. In the present research we report on the use of microdiamond instead of nanodiamond in such composites. Microdiamond is more favourable than nanodiamond in view of phonon transport performance leading to better thermal conductivity. However, there is a trade off between densification and thermal conductivity as the SPS temperature increases tungsten carbide formation from microdiamond is accelerated inevitably while the consolidation density would rise.

  3. Volatility from copper and tungsten alloys for fusion reactor applications

    International Nuclear Information System (INIS)

    Accident scenarios for fusion power plants present the potential for release and transport of activated constituents volatilized from first wall and structural materials. The extent of possible mobilization and transport of these activated species, many of which are ''oxidation driven'', is being addressed by the Fusion Safety Program at the Idaho National Engineering Laboratory (INEL). This report presents experimental measurements of volatilization from a copper alloy in air and steam and from a tungsten alloy in air. The major elements released included zinc from the copper alloy and rhenium and tungsten from the tungsten alloy. Volatilization rates of several constituents of these alloys over temperatures ranging from 400 to 1200 degree C are presented. These values represent release rates recommended for use in accident assessment calculations. 8 refs., 3 figs., 5 tabs

  4. Tungsten trioxide thin films prepared by electrostatic spray deposition technique

    International Nuclear Information System (INIS)

    Tungsten trioxide (WO3) thin films deposited on a Pt-coated alumina substrate using the electrostatic spray deposition (ESD) technique is reported in this paper. As precursor solution, tungsten (VI) ethoxide in ethanol was used. The morphology and the microstructure of the films were studied using scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Dense to porous morphologies were obtained by tuning the deposition temperature. Impedance spectroscopy and current-voltage measurements were used to study the electrical behaviour of the films in air, in temperature range 300-500 deg. C. The activation energy was estimated from Arrhenius plots. Considering the obtained results, the ESD technique proved to be an effective technique for the fabrication of porous tungsten trioxide thin films

  5. Sequential and simultaneous thermal and particle exposure of tungsten

    Science.gov (United States)

    Steudel, I.; Huber, A.; Kreter, A.; Linke, J.; Sergienko, G.; Unterberg, B.; Wirtz, M.

    2016-02-01

    The broad array of expected loading conditions in a fusion reactor such as ITER necessitates high requirements on the plasma facing materials (PFMs). Tungsten, the PFM for the divertor region, the most affected part of the in-vessel components, must thus sustain severe, distinct exposure conditions. Accordingly, comprehensive experiments investigating sequential and simultaneous thermal and particle loads were performed on double forged pure tungsten, not only to investigate whether the thermal and particle loads cause damage but also if the sequence of exposure maintains an influence. The exposed specimens showed various kinds of damage such as roughening, blistering, and cracking at a base temperature where tungsten could be ductile enough to compensate the induced stresses exclusively by plastic deformation (Pintsuk et al 2011 J. Nucl. Mater. 417 481-6). It was found out that hydrogen has an adverse effect on the material performance and the loading sequence on the surface modification.

  6. Field-emission spectroscopy of beryllium atoms adsorbed on tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, J.J.; Grzesiak, W.; Krajniak, J. (Politechnika Wroclawska (Poland))

    1981-01-01

    Field emission energy distributions (FEED) have been measured for the beryllium-tungsten (023) adsorption system over the 78-450 K temperature range. A temperature dependence of the normalized half-width, ..delta../d, of FEED peaks changed significantly due to beryllium adsorption; and the curve, ..delta../d vs p, for the Be/W adsorption system was identical in character to the calculated curve based on the free electron model in contrast to the curve for the clean tungsten surface. In the last part of this paper Gadzuk's theory of the resonance-tunneling effect is applied to the beryllium atom on tungsten. Experimental and theoretical curves of the enhancement factor as a function of energy have been discussed.

  7. Synthesis of Tungsten Diselenide Nanoparticles by Chemical Vapor Condensation Method

    Directory of Open Access Journals (Sweden)

    Oleg V. Tolochko

    2015-09-01

    Full Text Available Crystalline tungsten diselenide (WSe2 nanoparticles have been synthesized by a gas phase reaction using tungsten hexacarbonyl and elemental selenium as precursors. The WSe2 nanoparticle morphology varies from the spherical shape to flake-like layered structures. Mean size in smaller dimension are less than 5 nm and the number of layers decreased linearly with decreasing of reaction time and concentration of carbonyl in the gas phase. The mean value of interlayer distance in <0001> direction is comparable with the microscopic values. The selenium-to-tungsten atomic ratios of 2.07, 2.19 and 2.19 were determined respectively, approach to the stoichiometric ratio of 2:1. Main impurities are oxygen and carbon and strongly interrelated with carbonyl concentration in the gas phase.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7356

  8. Mechanism of vacancy formation induced by hydrogen in tungsten

    Directory of Open Access Journals (Sweden)

    Yi-Nan Liu

    2013-12-01

    Full Text Available We report a hydrogen induced vacancy formation mechanism in tungsten based on classical molecular dynamics simulations. We demonstrate the vacancy formation in tungsten due to the presence of hydrogen associated directly with a stable hexagonal self-interstitial cluster as well as a linear crowdion. The stability of different self-interstitial structures has been further studied and it is particularly shown that hydrogen plays a crucial role in determining the configuration of SIAs, in which the hexagonal cluster structure is preferred. Energetic analysis has been carried out to prove that the formation of SIA clusters facilitates the formation of vacancies. Such a mechanism contributes to the understanding of the early stage of the hydrogen blistering in tungsten under a fusion reactor environment.

  9. High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap

    OpenAIRE

    Han Chulwoong; Na Hyunwoong; Choi Hanshin; Kim Yonghwan

    2015-01-01

    Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungs...

  10. Effect of additions of Cr, Mo, W and/or Si on the technological properties of aluminum-iron-nickel bronze

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2011-07-01

    Full Text Available The aim of this study was to investigate the effect of additives of Cr, Mo, W and / or Si CuAl10Fe5Ni5 bronze, cast into sand moulds, the bronze technological properties such as: porosity, volumetric shrinkage Sv, linear shrinkage s and prone hot to cracking. The study relate to the newly developed grades aluminum-iron-nickel bronze, with additions of Cr, Mo, W and/or Si. In order to determine the technological properties of the test castings were made in the form of moulding sand, which made the mould cavities designed patterns. To evaluate the porosity and volumetric shrinkage was used for digital image analysis method. Volumetric shrinkage was determined using developed, the new method, the surface shrinkage Svp designation, and then converting it to the volumetric shrinkage, using prepared relation Sv=f(Djs*Svp. It was found that made the bronze alloy additions to reduce the size of pores surface area of gas and shrinkage in the test bronze. The probability of microporosity with an area of 0.002560÷0.120647 mm2 can be described by gamma distribution. Changing the chemical composition of the grades tested bronze strongly alter the first volumetric shrinkage Sv, and less to change the linear shrinkage s. The increase in gas porosity and shrink in bronze reduces the volumetric shrinkage and linear. The addition of Cr, Mo, W and/or Si to the bronze CuAl10Fe5Ni5 does not change its prone to hot cracking.

  11. Corrosion stability of different bronzes in simulsted urban rain: Korozijska stabilnost različnih bronov v umetnem kislem dežju:

    OpenAIRE

    Kosec, Tadeja; Kuhar, Viljem; Legat, Andraž; Švara Fabjan, Erika

    2011-01-01

    Copper and high copper alloys tend to passivate in humid air. In clean humid air, cuprite slowly transforms to black tenorite. If atmosphere contains aggressive species, acid rain might effect the formation of different corrosion products. The patina that forms upon exposure to urban acid rain also depends of the composition of the base alloy. In the present study three different alloys were investigated: leaded bronze, usually used for sculptures, unleaded bronze as an alloy without an impac...

  12. Nanocomposite anode materials for sodium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  13. Loss of Balance between Tungsten Reserve and Mining, China’s Resource Advantage Is Weakening

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>China’s tungsten reserve, product output, export trade volume and consumption all rank top in the world. By offering supply for more than 80% global tungsten consumption with less than 50% of global tungsten ore resource, China has made significant contribution to the development of

  14. Effect of neon plasma pre-irradiation on surface morphology and deuterium retention of tungsten

    NARCIS (Netherlands)

    Cheng, L.; De Temmerman, G.; van Emmichoven, P. A. Zeijlma; Ji, G.; Zhou, H. B.; Wang, B.; Yuan, Y.; Zhang, Y.; Lu, G. H.

    2015-01-01

    Neon and deuterium plasma irradiation of polycrystalline tungsten targets have been performed at high fluxes of ∼1024 ions m−2 s−1 to study the interaction of neon with tungsten and the influence of neon on deuterium retention. Tungsten exposure to neon plasma leads to the

  15. Microstructure and Texture Changes of Tungsten-Rhenium coated on Carbon Fiber Composite during Annealing

    Institute of Scientific and Technical Information of China (English)

    LIUXiang; XUZengyu; S.Tamura; N.Yoshida

    2002-01-01

    Since tungsten was chose as the divertor tiles of 1TER, the investigation of tungsten and its coating as plasma facing material (PFM) have been paid more attentions by fusion scientists all over the world. Recent years, tungsten coatings have been successfully

  16. Polaron transitions in charge intercalated amorphous tungsten oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saenger, M.F.; Hofmann, T.; Schubert, M. [Department of Electrical Engineering, and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln (United States); Hoeing, T. [Flabeg GmbH and Co. KG, Furth im Wald (Germany)

    2008-04-15

    We present a parametric dielectric function model in dependence of the intercalated charge per tungsten ion ratio x, which excellently describes the ellipsometric experimental data, and allows the identification of two polaron modes corresponding to transitions between W{sup 4+} and W{sup 5+} and between W{sup 5+} and W{sup 6+} tungsten ion sites. A competitive relation between the two polaron transitions is found. An empirical relation for the amplitude of the polaron transitions is found useful to provide a good description of the polaron transition dependence on x. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. First-principles study on migration of vacancy in tungsten

    International Nuclear Information System (INIS)

    We calculated the binding and migration energies of mono-vacancies and di-vacancies in tungsten material using density functional theory. Mono-vacancies diffuse in the [111] direction easier than in the [001] direction. The migration energies of mono-vacancies and di-vacancies are almost the same; moreover, the migration of mono-vacancies and di-vacancies is nearly similar. The di-vacancy binding energies are almost zero or negative. The interactions between two vacancies in tungsten material are repulsive from the second to the fifth nearest neighbors. The vacancies are difficult to aggregate because di-vacancies are less stable than mono-vacancies. (author)

  18. Production And Characterization Of Tungsten-Based Positron Moderators

    International Nuclear Information System (INIS)

    Experiments of interest in Atomic Physics require production of well-defined low-energy positron beams through a moderation process of high-energy positrons, which can be produced by either the use of a radioactive source or by accelerator based pair production process. Tungsten is one of the most commonly used moderator materials because of its reasonable efficiency, high work function and relatively low cost. In this work we present different methods to produce tungsten-based candidate moderators in a variety of shapes. We also present results from characterizing these candidate moderators by ion beam analysis and microscopy techniques.

  19. The WiZard/CAPRICE silicon-tungsten calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Bocciolini, M.; Celletti, F.; Finetti, N.; Grandi, M.; Papini, P.; Perego, A.; Piccardi, S.; Spillantini, P. [Florence Univ. (Italy). Dip. di Fisica]|[INFN, Florence (Italy); Bidoli, V.; Candusso, M. [Rome Univ. `Tor Vergata` (Italy). Dip. di Fisica]|[INFN, Sezione di Roma II (Italy)

    1995-09-01

    A silicon-tungsten calorimeter has been developed to be flown in the WiZard/ CAPRICE balloon borne experiment to measure the flux of antiprotons, positrons and light nuclei in the cosmic radiation. The calorimeter is composed of 8 x, y silicon sampling planes (active area (48x48) cm{sup 2}) interleaved with 7 tungsten absorbers (7 radiation lengths); it provides the topology of the interacting events together with an independent measurement of the deposited energy. Details of the front-end electronics and of the read-out system are given and the overall performances during pre-flight ground operations are described as well.

  20. The WiZard/CAPRICE silicon-tungsten calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Bocciolini, M. [Florence Univ. (Italy). Dipt. di Fisica; Celletti, F. [Florence Univ. (Italy). Dipt. di Fisica; Finetti, N. [Florence Univ. (Italy). Dipt. di Fisica; Grandi, M. [Florence Univ. (Italy). Dipt. di Fisica; Papini, P. [Florence Univ. (Italy). Dipt. di Fisica; Perego, A. [Florence Univ. (Italy). Dipt. di Fisica; Piccardi, S. [Florence Univ. (Italy). Dipt. di Fisica; Spillantini, P. [Florence Univ. (Italy). Dipt. di Fisica; Bidoli, V. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Candusso, M. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Casolino, M. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); De Pascale, M.P. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Morselli, A. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Picozza, P. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Sparvoli, R. [Dipartimento di Fisica dell`Universita `Tor Vergata`, and Sezione INFN di Roma 1I (Italy); Basini, G. [Laboratori Nazionali INFN, Frascati (Italy); Mazzenga, G. [Laboratori Nazionali INFN, Frascati (Italy); Ricci, M. [Laboratori Nazionali INFN, Frascati (Italy); Bronzini, F. [Dipartimento di Fisica dell`Universita `La Sapienza`, and Sezione INFN di Roma (Italy); Barbiellini, G. [Dipartimento di Fisica dell`Universita, Trieste and Sezione INFN di Trieste, Trieste (Italy); Boezio, M. [Dipartimento di Fisica dell`Universita, Trieste and Sezione INFN di Trieste, Trieste (Italy); Bravar, U. [Dipartimento di Fisica dell`Universita, Trieste and Sezione INFN di Trieste, Trieste (Italy); Fratnik, F. [Dipartimento di Fisica dell`Universita, Trieste and Sezione INFN di Trieste, Trieste (Italy); Schiavon, P. [Dipartimento di Fisica dell`Universita, Trieste and Sezione INFN di Trie (Italy)

    1996-02-21

    A silicon-tungsten calorimeter has been developed to be flown in the WiZard/CAPRICE balloon borne experiment to measure the flux of antiprotons, positrons and light nuclei in the cosmic radiation. The calorimeter is composed of 8 x,y silicon sampling planes [active area (48 x 48) cm{sup 2}] interleaved with 7 tungsten absorbers (7 radiation lengths); it provides the topology of the interacting events together with an independent measurement of the deposited energy. Details of the front-end electronics and of the read-out system are given and the overall performances during pre-flight ground operations are described as well. (orig.).

  1. Preparation of Ultrafine Tungsten Powder by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    Yuxian HAN; Tai QIU; Tao SONG

    2008-01-01

    Sol-gel method was employed for the preparation of nanoscale tungsten powder. The effects of different preparation conditions on particle size were discussed and the optimum preparation condition was found.The products were characterized by X-ray diffraction, scan electron microscopy and so on. The results show that the intermediate is monoclinic WO3, its particle shape is approximately spherical, and the particle size distribution is narrow. The average particle size is about 60 nm. After deoxidization, WO3 turns into cubic tungsten powder with small particle size (average particle size about 120 nm) and narrow size distribution.

  2. Electrolyte for deposition of coatings from nickel-tungsten alloy

    International Nuclear Information System (INIS)

    A new electrolyte to deposite coatings of nickel-tungsten alloy is produced. To increase microhardness of the coatings at the expense of tungsten content increase it contains additionally potassium iodide, and as a salt of tungstic acid-ammonium tungstate. The invention can be used when manufacturing strain-resistant, threshold strain-resistant, impulse, mixing and SHF-diodes on the basis of silicon. It is shown, that the electrolyte suggested permitted to achieve a two-time increase in the coating microhardness at the expense of tungstent increase in the coating

  3. Tungsten spectra recorded at the LHD and comparison with calculations

    OpenAIRE

    Harte, Colm S.; Suzuki, C.; Kato, T; Sakaue, H.A.; Kato, D.; Sato, K.; Tamura, N.; Sudo, S.; D'Arcy, Rebekah; Sokell, Emma; White, John K.; O'Sullivan, Gerry

    2010-01-01

    We have measured extreme ultraviolet (EUV) spectra from highly charged tungsten ions in low-density and high-temperature plasmas produced in the Large Helical Device at the National Institute for Fusion Science. The EUV spectra emitted after injection of a tungsten pellet into a hydrogen plasma were recorded at plasma temperatures of 1.5 and 3 keV and were dominated by an intense transition array in the 4.5–6.5 nm region, the profile and extent of which was different in both spectra. Some dis...

  4. L-SHELL IONIZATION MEASUREMENT OF TUNGSTEN BY ELECTRON IMPACT

    Institute of Scientific and Technical Information of China (English)

    PENG XIU-FENG; HE FU-QING; LONG XIAN-GUAN

    2000-01-01

    L-shell partial production cross sections of Lα- , Lβ-, Lγ- rays by electron impact were measured by observing the counts of X-ray from impacted thin tungsten target. Total production cross sections and mean ionization cross sections were deduced from these measured results. The electron beam energy range was from 11 to 36 keV. Tungsten was sputtered onto a carbon backing to reduce bremsstrahlung of the backing. The effect of electrons reflected by the backing has been corrected. Comparison with two theoretical calculations has performed. The experimental results agree rather well with the theoretical predications.

  5. Structural, electrochemical and optical comparisons of tungsten oxide coatings derived from tungsten powder-based sols

    Energy Technology Data Exchange (ETDEWEB)

    Isik, Dilek, E-mail: e145342@metu.edu.t [Department of Metallurgical and Materials Engineering, METU, 06531 Ankara (Turkey); Ak, Metin, E-mail: metinak@pamukkale.edu.t [Department of Chemistry, Pamukkale University, 20017 Denizli (Turkey); Durucan, Caner, E-mail: cdurucan@metu.edu.t [Department of Metallurgical and Materials Engineering, METU, 06531 Ankara (Turkey)

    2009-11-02

    Tungsten trioxide (WO{sub 3}) electrochromic coatings have been formed on indium tin oxide-coated glass substrates by aqueous routes. Coating sols are obtained by dissolving tungsten powder in acetylated (APTA) or plain peroxotungstic acid (PTA) solutions. The structural evolution and electrochromic performance of the coatings as a function of calcination temperature (250 {sup o}C and 400 {sup o}C) have been reported. Differential scanning calorimetry and X-ray diffraction have shown that amorphous WO{sub 3} films are formed after calcination at 250 {sup o}C for both processing routes; however, the coatings that calcined at 400 {sup o}C were crystalline in both cases. The calcination temperature-dependent crystallinity of the coatings results in differences in optical properties of the coatings. Higher coloration efficiencies can be achieved with amorphous coatings than could be seen in the crystalline coatings. The transmittance values (at 800 nm) in the colored state are 35% and 56% for 250 {sup o}C and 400 {sup o}C-calcined coatings, respectively. The electrochemical properties are more significantly influenced by the method of sol preparation. The ion storage capacities designating the electrochemical properties are found in the range of 1.62-2.74 x 10{sup -3} (mC cm{sup -2}) for APTA coatings; and 0.35-1.62 x 10{sup -3} (mC cm{sup -2}) for PTA coatings. As a result, a correlation between the microstructure and the electrochromic performance has been established.

  6. Les techniques de soudage de la grande statuaire antique en bronze: étude des paramètres thermiques et chimiques contrôlant le soudage par fusion au bronze liquide

    OpenAIRE

    Azéma, Aurélia

    2013-01-01

    Ces travaux s'inscrivent dans une recherche interdisciplinaire qui concerne l'évolution de l'ensemble des techniques de la grande statuaire antique en bronze (de la 2nd moitié du 6 siècle avant J.C. au 5e siècle après J.C.). L'objectif de la thèse est de contribuer à la compréhension du procédé de soudage par fusion au bronze liquide, en mettant en œuvre une double approche : étude de soudures antiques et essais expérimentaux en laboratoire. Les statues à étudier ont été choisies parmi les œu...

  7. Developments in sodium technology

    International Nuclear Information System (INIS)

    Sodium, because of its good heat transfer and nuclear properties, is used as a coolant in fast reactors. It is also used largely as a reducing agent in pharmaceutical, perfumery and general chemical industries. Its affinity to react with air and water is a strong disadvantage. However, this is fully understood and the design of engineering systems takes care of this aspect. With several experimental and test facilities established over the years in this country and abroad, 'sodium technology' has reached a level of maturity. The design of sodium systems considering all the physical and chemical properties and the development work carried out in this country are broadly covered in this article. (author)

  8. Sodium technology project

    International Nuclear Information System (INIS)

    The 1976 annual report of the subgroup Nuclear Energy of the organisation for Toegepast Natuurwetenschappelijk Onderzoek (TNO) discusses the research program related to the SNR-300 reactor. The program mainly comprises the properties of ferritic and austenitic construction steels, remote methods of repair (e.g. for welding of sodium moistured surfaces), calculational methods in the designing and large-scale testing of components for heat-transfer equipment, the properties of hydrogen in sodium systems (detection of leaks in steam generator pipes), the study of models for mass transport in sodium, wear and mechanical damage of pipes in heat exchangers

  9. Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

    International Nuclear Information System (INIS)

    To prevent the natural processes of decay and to develop and improve the treatments of conservation and restoration of artistic bronzes meaning statues and sculptures, it is important understanding the patination processes and the knowledge of artificially corroded surfaces. Chemical and physical characterization of artificial patinas obtained on artistic bronzes and coppers by using the 19th century Western traditional patination techniques and recipes by means of SEM-EDS, light microscopy and ATR/FT-IR has been done in previous studies [I.Z. Balta, L. Robbiola, Characterization of artificial black patinas on artistic cast bronze and pure copper by using SEM-EDS and light microscopy, in: Proceedings of the 13th European Microscopy Congress, 22-27 August 2004, Antwerp, Belgium, EMC 2004 CD-Rom Conference Preprints; I.Z. Balta, L. Robbiola, Traditional artificial artistic bronze and copper patinas-an investigation by SEM-EDS and ATR/FT-IR, in: Proceedings of the 8th International Conference on Non Destructive Investigations and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage, 15-19 May 2005, Lecce, Italy, ART'05 CD-Rom Conference Preprints]. Differences in morphology (structure, thickness, porosity, adherence, compactity, uniformity, homogeneity) and also in composition, on both artistic cast bronze and pure copper patinas, were clearly evidenced. Further in-depth investigation is required to be carried out in order to better understand the patinas mechanisms of formation and the layers kinetics of growth. The elemental and chemical analysis, either on a surface monolayer or in a depth profile, by using the Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS) techniques, can provide this kind of information, unique at trace-level sensitivity. SIMS has proved to be a suitable analytical technique for analyzing small amounts of material with high atomic sensitivity (ppm or even ppb) and high

  10. Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

    Science.gov (United States)

    Balta, I. Z.; Pederzoli, S.; Iacob, E.; Bersani, M.

    2009-04-01

    To prevent the natural processes of decay and to develop and improve the treatments of conservation and restoration of artistic bronzes meaning statues and sculptures, it is important understanding the patination processes and the knowledge of artificially corroded surfaces. Chemical and physical characterization of artificial patinas obtained on artistic bronzes and coppers by using the 19th century Western traditional patination techniques and recipes by means of SEM-EDS, light microscopy and ATR/FT-IR has been done in previous studies [I.Z. Balta, L. Robbiola, Characterization of artificial black patinas on artistic cast bronze and pure copper by using SEM-EDS and light microscopy, in: Proceedings of the 13th European Microscopy Congress, 22-27 August 2004, Antwerp, Belgium, EMC 2004 CD-Rom Conference Preprints; I.Z. Balta, L. Robbiola, Traditional artificial artistic bronze and copper patinas—an investigation by SEM-EDS and ATR/FT-IR, in: Proceedings of the 8th International Conference on Non Destructive Investigations and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage, 15-19 May 2005, Lecce, Italy, ART'05 CD-Rom Conference Preprints]. Differences in morphology (structure, thickness, porosity, adherence, compactity, uniformity, homogeneity) and also in composition, on both artistic cast bronze and pure copper patinas, were clearly evidenced. Further in-depth investigation is required to be carried out in order to better understand the patinas mechanisms of formation and the layers kinetics of growth. The elemental and chemical analysis, either on a surface monolayer or in a depth profile, by using the Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS) techniques, can provide this kind of information, unique at trace-level sensitivity. SIMS has proved to be a suitable analytical technique for analyzing small amounts of material with high atomic sensitivity (ppm or even ppb) and high

  11. Magnetization and Inter-Filament Contact in HEP and ITER Bronze-Route Nb(3)Sn Wires

    CERN Document Server

    Bordini, B; Devred, A; Richter, D; Bessette, D; Jewell, M; Bottura, L

    2011-01-01

    Magnetization measurements are relevant tests for the characterization of superconductors. Practically they are the only measurements that allow estimating the critical current density at low fields of low temperature superconductors, the effective filament size and the hysteresis losses. For this purpose CERN, in collaboration with the University of Geneva, has carried out magnetization measurements on five types of Nb(3)Sn wires: three bronze route strands used in the ITER project; one Powder In Tube (PIT) and one Internal Tin (IT) wires used for developing next generation accelerator magnets. The field dependent magnetization has been determined using three setups: a Vibrating Sample Magnetometer (VSM), a Superconducting Quantum Interference Device (SQUID) and a special system used for the production control of LHC strands. Samples of different lengths have been tested to check the different coupling between the filaments. Unexpectedly, it was found that the magnetization of the tested bronze wires was str...

  12. Magnetization and Inter-Filament Contact in HEP and ITER Bronze-Route Nb3Sn Wires

    CERN Document Server

    Bordini, B; Bottura, L; Devred, A; Jewell, M; Richter, D; Senatore, C

    2011-01-01

    Magnetization measurements are relevant tests for the characterization of superconductors. Practically they are the only measurements that allow estimating the critical current density at low fields of low temperature superconductors, the effective filament size and the hysteresis losses. For this purpose CERN, in collaboration with the University of Geneva, has carried out magnetization measurements on five types of Nb3Sn wires: three bronze route strands used in the ITER project; one Powder In Tube (PIT) and one Internal Tin (IT) wires used for developing next generation accelerator magnets. The field dependent magnetization has been determined using three set-ups: a Vibrating Sample Magnetometer (VSM), a Superconducting Quantum Interference Device (SQUID) and a special system used for the production control of LHC strands. Samples of different lengths have been tested to check the different coupling between the filaments. Unexpectedly, it was found that the magnetization of the tested bronze wires was stro...

  13. Simulation of tungsten plasma transport along magnetic field under ELM-like heat loads

    International Nuclear Information System (INIS)

    Tungsten plasma transport along the magnetic field calculated with the TOKES code has been validated using dedicated experiment in a plasma gun under the ELM-like conditions. The plasma velocity is in a good agreement with the measured one. The ion composition of the simulated tungsten plasma is in a qualitative agreement with the one reconstructed from the measured spectrum of the tungsten plasma, probably because of rather incomplete database for tungsten ions radiation. Nevertheless, it has been identified the radiation from cold and hot tungsten plasma regions with ion composition maxima at W7+–W8+ and W13+–W16+ correspondingly

  14. Gravimetric determination of tungsten with tetraphenylarsonium chloride after its extraction as thiocyanate

    International Nuclear Information System (INIS)

    Small amounts of tungsten in natural and industrial samples can be freed from all important interfering elements by extraction of molybdenum by xanthane, reduction of tungsten by mercury and extraction of tungsten (V) thiocyanate into tribenzylamine, and finally back-extraction. The tungsten can be then determined as tetraphenylarsonium tungstate by precipitating it at pH 2 to 4, filtering it off and drying it at 1100 for 45 min. An overall error of 0.1 to 0.2% is obtained for 5 to 60 mg of tungsten. (author)

  15. Oxygen isotope in archaeological bioapatites from India: Implications to climate change and decline of Bronze Age Harappan civilization

    OpenAIRE

    Anindya Sarkar; Arati Deshpande Mukherjee; Bera, M. K.; Das, B.; Navin Juyal; Morthekai, P.; Deshpande, R. D.; Shinde, V. S.; L. S. Rao

    2016-01-01

    The antiquity and decline of the Bronze Age Harappan civilization in the Indus-Ghaggar-Hakra river valleys is an enigma in archaeology. Weakening of the monsoon after ~5 ka BP (and droughts throughout the Asia) is a strong contender for the Harappan collapse, although controversy exists about the synchroneity of climate change and collapse of civilization. One reason for this controversy is lack of a continuous record of cultural levels and palaeomonsoon change in close proximity. We report a...

  16. MEASURING AND MODELING OF THE MECHANICAL PROPERTIES OF COMPOSITE BEARING PAD MADE OF PLASTIC MATRIX AND FINE BRONZE ELASTIC SPRINGS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The viscoelastic properties of the normal PTFE plastic and strengthened PTFE plastic for bearing pad are measured. The mechanical properties of the composite material for bearing pad, which is made of the aforementioned plastics as matrix reinforced by fine bronze elastic springs, are modeled and relaxation modulus of the material are presented. The difference between these two kinds of PTFE is studied. The results show that the complex modulus of PTFE plastics for bearing pad is higher than that of normal PTFE plastics.

  17. The Metallurgy of the Sicilian Final Bronze Age/Early Iron Age necropolis of Madonna del Piano (Catania, Sicily)

    OpenAIRE

    Giumlia-Mair, Alessandra; Albanese Procelli, Rosa Maria; Lo Schiavo, Fulvia

    2010-01-01

    This paper presents the analysis results of the copper- based finds, from the important Sicilian necropolis of Madonna del Piano, near Grammichele (Catania), dated between the local Final Bronze Age 2 and the Early Iron Age IA. 122 copper-based finds from the 273 graves (1970-71) of the large cemetery have been analysed. The sampled objects belong to different classes, there are for instance weapons of offence and defence, such as swords and greaves, small decorative objects for personal use,...

  18. Recent Progress in Processing of Tungsten Heavy Alloys

    Directory of Open Access Journals (Sweden)

    Y. Şahin

    2014-01-01

    Full Text Available Tungsten heavy alloys (WHAs belong to a group of two-phase composites, based on W-Ni-Cu and W-Ni-Fe alloys. Due to their combinations of high density, strength, and ductility, WHAs are used as radiation shields, vibration dampers, kinetic energy penetrators and heavy-duty electrical contacts. This paper presents recent progresses in processing, microstructure, and mechanical properties of WHAs. Various processing techniques for the fabrication of WHAs such as conventional powder metallurgy (PM, advent of powder injection molding (PIM, high-energy ball milling (MA, microwave sintering (MW, and spark-plasma sintering (SPS are reviewed for alloys. This review reveals that key factors affecting the performance of WHAs are the microstructural factors such as tungsten and matrix composition, chemistry, shape, size and distributions of tungsten particles in matrix, and interface-bonding strength between the tungsten particle and matrix in addition to processing factors. SPS approach has a better performance than those of others, followed by extrusion process. Moreover, deformation behaviors of WHA penetrator and depleted uranium (DU Ti alloy impacting at normal incidence both rigid and thick mild steel target are studied and modelled as elastic thermoviscoplastic. Height of the mushroomed region is smaller for α=0.3 and it forms sooner in each penetrator as compared to that for α=0.2.

  19. Helium effects on tungsten surface morphology and deuterium retention

    NARCIS (Netherlands)

    Ueda, Y.; H. Y. Peng,; H. T. Lee,; N. Ohno,; S. Kajita,; Yoshida, N.; Doerner, R.; De Temmerman, G.; V. Alimov,; G. Wright,

    2013-01-01

    Recent experimental results on tungsten surface morphology, especially nano-structure (fuzz), induced by helium plasma exposure at temperatures between 1000 K and 2000 K are reviewed. This structure was firstly reported in 2006. In this review, most of experimental results reported

  20. Geochemistry of the Panasqueira tungsten-tin deposit, Portugal

    NARCIS (Netherlands)

    Bussink, R.W.

    1984-01-01

    Major tin-tungsten deposits in Portugal are related to intrusions of the Younger Series (300-280 Ma) of Hercynian granitoids. Mineralized granites are 'specialized' by a specific increase or decrease of major, minor and trace element contents in comparison with non-mineralized occurrences. Component

  1. Thermal Desorption of Helium Implanted in Tungsten at RT

    Institute of Scientific and Technical Information of China (English)

    ZHANGFu; XUZengyu; LIUXiang; CHENJiming; XUYing; N.Yoshida; H.Iwakiri

    2002-01-01

    Tungsten is envisaged as one of the main candidate materials for divertor plate of ITER and future fusion reactors. Due to D-T reaction, PFMs would suffer helium irradiation from plasma additional to the high heat loads. Helium retention and thermal desorption behavior are largely concerned.

  2. Preparation of tungsten disulfide motor oil and its tribological characteristics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Through using mineral oil and synthetic oil to deploy the semisynthesis base oil, modifying the surfaces of ultrafine tungsten disulfide grains by surface chemical embellishment and adsorption embellishment to make them suspended steadily in the base oil as solid lubricating additive, and adding some function additives, the tungsten disulfide motor oil was prepared. The tribological characteristics of this kind motor oil and the well-known motor oils in our country and overseas were studied. The results show that the oil film strength of this kind of motor oil is respectively 1.06 and 1.38 times of that of shell helix ultra motor oil and great wall motor oil, and its sintering load is 1.75 and 2.33 times of that of them, and when tested under 392 N, 1 450 r/min and 30 min, the friction coefficients of friction pairs lubricated by the tungsten disulfide motor oil decrease with the increase of time, meanwhile, the diameter of worn spot is small, and the surface of worn spot is smooth, and no obvious furrows appear. The experiments indicate that the tungsten disulfide motor oil has the better antiwear, antifriction and extreme pressure properties than the well-known motor oils.

  3. Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

    Energy Technology Data Exchange (ETDEWEB)

    Z. Zak Fang, H. Y. Sohn

    2009-03-10

    This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

  4. Isothermal diffusion in tungsten-molybdenum-rhenium system

    International Nuclear Information System (INIS)

    Paper investigates into the regularities of diffusion interaction within α-region of tungsten-molybdenum-rhenium ternary system. Experimental determination of coefficients of mutual diffusion in binary diffusion pair was carried out using Matano method. Element distribution within diffusion range was determined by means of micro-X-ray-spectral analysis. 6 refs., 3 figs

  5. Fluorine solubility in liquid hexafluorides of uranium, tungsten and molybdenum

    International Nuclear Information System (INIS)

    Experimental data on fluorine solubility in liquid uranium, tungsten and molybdenum hexafluorides in the range 66-90 Deg C and fluorine partial pressure 226-1066 kPa are performed. Calculation values of the Henry constant for these systems and equilibrium constants of approximation by linearization of Henry constant temperature dependence are given

  6. Observations of multiply ionized tungsten radiation in the PLT discharges

    Energy Technology Data Exchange (ETDEWEB)

    Hinnov, E.; Mattioli, M.

    1977-10-01

    Spectral and spatial distributions of radiation bands with peaks at 33, 51 and 60 A, ascribed to 4d-4f transitions of tungsten ions in the range about W XX to W XXXV, have been measured in discharges of different electron temperatures.

  7. Erosion Behavior of the Materials on Basis of Tungsten

    International Nuclear Information System (INIS)

    It is presented in this work the results of the erosion behavior examination of the materials on the basis of tungsten which have been produced with the use of different technologies (vacuum-arc coating deposition, chemical vapor deposition, hot pressing in a vacuum) under steady state Penning discharge plasma irradiation

  8. Sodium carbonate poisoning

    Science.gov (United States)

    Sodium carbonate is found in: Automatic dishwashing soaps Clinitest (diabetes testing) tablets Glass products Pulp and paper products Some bleaches Some bubble bath solutions Some steam iron cleaners Note: This list is not all-inclusive.

  9. Fractional excretion of sodium

    Science.gov (United States)

    ... skin) Infection (a slight risk any time the skin is broken) Multiple punctures to locate veins There are no risks with the urine sample. Alternative Names FE sodium; FENa Images Male urinary system References Parikh CR, ...

  10. Sodium urine test

    Science.gov (United States)

    ... urine sodium level may be a sign of: Adrenal glands releasing too much hormone ( hyperaldosteronism ) Not enough fluid in the body (dehydration) Diarrhea and fluid loss Heart failure Kidney problems, such as chronic kidney disease or ...

  11. Sodium bicarbonate and sodium citrate: ergogenic aids?

    Science.gov (United States)

    Requena, Bernardo; Zabala, Mikel; Padial, Paulino; Feriche, Belén

    2005-02-01

    Numerous studies have used exogenous administration of sodium bicarbonate (NaHCO(3)) and sodium citrate (Na-citrate) in an attempt to enhance human performance. After ingestion of NaHCO(3) and Na-citrate, two observations have been made: (a) There was great individual variability in the ergogenic benefit reached, which can be attributed to the level of physical conditioning of the subjects and to their tolerance of the buffer substance; and (b) the subjects who had ingested NaHCO(3) and Na-citrate show higher levels of pH, bicarbonate, and lactate ions concentrations in their exercising blood than do the subjects who had ingested the placebo. A majority of the studies have suggested that the ingestion of both substances provides an ergogenic effect due to the establishment and maintenance of an elevated pH level during exercise. However, the exact mechanism by which the ergogenic effects occur has not been demonstrated conclusively. Sodium bicarbonate and Na-citrate seem to be effective in activities with a sufficient duration to generate a difference in the hydrogen ion gradient, characterized by a very high intensity and involving large muscular groups. However, in activities of equally high intensity, but with longer duration, the results obtained have been conflicting and inconclusive. PMID:15705037

  12. A theoretical and experimental study on the pulsed laser dressing of bronze-bonded diamond grinding wheels

    Science.gov (United States)

    Deng, H.; Chen, G. Y.; Zhou, C.; Zhou, X. C.; He, J.; Zhang, Y.

    2014-09-01

    A series of theoretical analyses and experimental investigations were performed to examine a pulsed fiber-laser tangential profiling and radial sharpening technique for bronze-bonded diamond grinding wheels. The mechanisms for the pulsed laser tangential profiling and radial sharpening of grinding wheels were theoretically analyzed, and the four key processing parameters that determine the quality, accuracy, and efficiency of pulsed laser dressing, namely, the laser power density, laser spot overlap ratio, laser scanning track line overlap ratio, and number of laser scanning cycles, were proposed. Further, by utilizing cylindrical bronze wheels (without diamond grains) and bronze-bonded diamond grinding wheels as the experimental subjects, the effects of these four processing parameters on the removal efficiency and the surface smoothness of the bond material after pulsed laser ablation, as well as the effects on the contour accuracy of the grinding wheels, the protrusion height of the diamond grains, the sharpness of the grain cutting edges, and the graphitization degree of the diamond grains after pulsed laser dressing, were explored. The optimal values of the four key processing parameters were identified.

  13. Multipeak self-biased magnetoelectric coupling characteristics in four-phase Metglas/Terfenol-D/Be-bronze/PMN-PT structure

    Science.gov (United States)

    Huang, Dongyan; Lu, Caijiang; Bing, Han

    2015-04-01

    This letter develops a self-biased magnetoelectric (ME) structure Metglas/Terfenol-D/Be-bronze/PMN-PT (MTBP) consisting of a magnetization-graded Metglas/Terfenol-D layer, a elastic Be-bronze plate, and a piezoelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) plate. By using the magnetization-graded Metglas/Terfenol-D layer and the elastic Be-bronze plate, multi-peak self-biased ME responses are obtained in MTBP structure. The experimental results show that the MTBP structure with two layers of Metglas foil has maximum zero-biased ME voltage coefficient (MEVC). As frequency increases from 0.5 to 90 kHz, eleven large peaks of MEVC with magnitudes of 0.75-33 V/(cm Oe) are observed at zero-biased magnetic field. The results demonstrate that the proposed multi-peak self-biased ME structure may be useful for multifunctional devices such as multi-frequency energy harvesters or low-frequency ac magnetic field sensors.

  14. Multipeak self-biased magnetoelectric coupling characteristics in four-phase Metglas/Terfenol-D/Be-bronze/PMN-PT structure

    Directory of Open Access Journals (Sweden)

    Dongyan Huang

    2015-04-01

    Full Text Available This letter develops a self-biased magnetoelectric (ME structure Metglas/Terfenol-D/Be-bronze/PMN-PT (MTBP consisting of a magnetization-graded Metglas/Terfenol-D layer, a elastic Be-bronze plate, and a piezoelectric 0.67Pb(Mg1/3Nb2/3O3-0.33PbTiO3 (PMN-PT plate. By using the magnetization-graded Metglas/Terfenol-D layer and the elastic Be-bronze plate, multi-peak self-biased ME responses are obtained in MTBP structure. The experimental results show that the MTBP structure with two layers of Metglas foil has maximum zero-biased ME voltage coefficient (MEVC. As frequency increases from 0.5 to 90 kHz, eleven large peaks of MEVC with magnitudes of 0.75-33 V/(cm Oe are observed at zero-biased magnetic field. The results demonstrate that the proposed multi-peak self-biased ME structure may be useful for multifunctional devices such as multi-frequency energy harvesters or low-frequency ac magnetic field sensors.

  15. Recent activity in development of bronze-processed Nb3Sn Wires. Improvements in strand performance and cabling

    International Nuclear Information System (INIS)

    Bronze-processed Nb3Sn wires have been used in practical applications of high-field magnets and large-scale magnets. Since the 1980s, Furukawa Electric Co., Ltd. has been developing and manufacturing many high-performance bronze-processed Nb3Sn wires. This paper describes our recent activity in development of the bronze-processed Nb3Sn wires. The non-Cu critical current density of the ITER-type strand was 1,150 A/mm2 at 12 T and 4.2 K, which is 1.8 times higher than that of the ITER-CS model coil 15 years ago. High-strength Nb3Sn wires reinforced with Cu-Ni/Nb-Ti or Cu-Nb composites have been successfully fabricated for high-field magnets. Enhancements of the superconducting properties resulting from pre-bending effects were demonstrated with Cu-Nb reinforced Nb3Sn wires. Mass production of practical cables for JT-60SA CS coils have been completed in exact accordance with the specifications. In addition, experimental manufacture of ITER-CSJA1 cables was properly carried out. Furthermore, a novel type of aluminum-alloy jacketed Nb3Sn conductor has been developed using the friction stir welding (FSW) technique. (author)

  16. Bronze Age pottery from the Aeolian Islands: definition of Temper Compositional Reference Units by an integrated mineralogical and microchemical approach

    Science.gov (United States)

    Brunelli, D.; Levi, S. T.; Fragnoli, P.; Renzulli, A.; Santi, P.; Paganelli, E.; Martinelli, M. C.

    2013-12-01

    An integrated microchemical-petrographic approach is here proposed to discriminate the provenance of archaeological pottery artefacts from distinct production centres. Our study focuses on a statistically significant sampling ( n=186) of volcanic temper-bearing potteries representative of the manufacturing and dispersion among the islands of the Aeolian Archipelago during the Bronze Age. The widespread establishment of new settlements and the abundant recovery of Aeolian-made ceramic in southern Italy attest for the increased vitality of the Archipelago during the Capo Graziano culture (Early Bronze Age-Middle Bronze Age 2; 2300-1430 BC). Potteries from three of the main known ancient communities (Lipari, Filicudi and Stromboli) have been studied integrating old collections and newly excavated material. Volcanic tempers have been first investigated through multivariate analyses of relative abundances of mineral and rock clasts along with petrographic characters. In addition, we performed in-situ mineral chemistry microanalyses by Electron Microprobe and Laser Ablation—Inductively Coupled Plasma Mass Spectrometry to assess major and trace element composition of the most common mineral phases. Four Temper Compositional Reference Units have been recognised based on compositional trends. Two units (AI and AX) are unequivocally distinct by their peculiar trace element enrichment and petrographic composition; they mostly contain samples from the sites of Lipari and Stromboli, respectively. Units AIV and AVIII, restricted to the sites of Filicudi and Stromboli, show distinct petrographic characters but overlapped geochemical fingerprints.

  17. Isotopic Evidence For The Primary Production, Provenance And Trade Of Late Bronze Age Glass In The Mediterranean.

    Science.gov (United States)

    Henderson, J.; Evans, J.; Nikita, K.

    The earliest known man made glass comes from Mesopotamia and dates to the 23rd century BC. By the 16th century BC the first glass vessels appear in Mesopotamia, but the earliest evidence for the fusion of glass from raw materials has been found at the 13th century BC Egyptian site of Qantir. Chemical analyses of this elite Late Bronze Age material have produced compositional distinctions between glasses found in Mesopotamia and Egypt. It is however debatable whether trace element concentrations provide a (geological) provenance for the glasses. By using neodymium and strontium isotopes to fingerprint well-dated chemically analysed 15th to 11th century BC glass samples, we show that independent primary production probably occurred in both Egypt and Mesopotamia in the 14th century BC, and that both of these areas exported glass to Greece. We also discuss the technological implications for glass manufacture and colouring that these new data provide. The results add significant new scientific evidence for glass trade between Late Bronze Age palatial societies. Moreover, it is the first time that this methodology has been used to investigate Bronze Age glass.

  18. Pulse current electrodeposition of tungsten coatings on V–4Cr–4Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Fan, E-mail: jiangfan1109@163.com; Zhang, Yingchun, E-mail: zycustb@163.com; Li, Xuliang

    2015-04-15

    Highlights: • Tungsten coatings were successfully electroplated on vanadium alloy substrate. • Tungsten coatings consisted of two sub-layers. • Tungsten coatings plated at lower duty cycle has a better surface quality. • High heat flux property of tungsten coatings was investigated. • Helium ion irradiation property of tungsten coatings was investigated. - Abstract: Tungsten coatings with high (2 2 0)-orientation were formed on V alloy substrate by pulse current electrodeposition in air atmosphere. The coatings’ microstructure, crystal structure and adhesive strength between coatings and substrates were investigated. It could be observed the tungsten coatings consisted of two sub-layers with the inner tooth-like layer, and the outer columnar layer. The tungsten coatings deposited at lower duty cycle have a better surface quality with a little change in the adhesive strength. The tungsten coating was exposed to electron beam with power density of 200 MW/m{sup 2} in the thermal shock test, the tungsten crystal grain surface melt, the microcracks are found among the crystal grains. Exfoliation, flaking and dense needle-like holes were observed on the tungsten coating after irradiation with helium ions at an energy of 65 keV and an implanted dose of 22.67 × 10{sup 18} cm{sup −2}.

  19. Separate vaporisation of boric acid and inorganic boron from tungsten sample cuvette-tungsten boat furnace followed by the detection of boron species by inductively coupled plasma mass spectrometry and atomic emission spectrometry (ICP-MS and ICP-AES).

    Science.gov (United States)

    Kataoka, Hiroko; Okamoto, Yasuaki; Tsukahara, Satoshi; Fujiwara, Terufumi; Ito, Kazuaki

    2008-03-10

    Utilising extremely different vaporisation properties of boron compounds, the determination procedures of volatile boric acid and total boron using tungsten boat furnace (TBF) ICP-MS and TBF-ICP-AES have been investigated. For the determination of volatile boric acid by TBF-ICP-MS, tetramethylammonium hydroxide (TMAH, Me(4)NOH) was used as a chemical modifier to retain it during drying and ashing stages. As for the total boron, not only non-volatile inorganic boron such as boron nitride (BN), boron carbide (B(4)C), etc. but also boric acid (B(OH)(3)) was decomposed by a furnace-fusion digestion with NaOH to produce sodium salt of boron, a suitable species for the electrothermal vaporisation (ETV) procedure. The proposed method was applied to the analysis of various standard reference materials. The analytical results for various biological and steel samples are described.

  20. Bronze Age metal artefacts found on Cyprus - metal from Anatolia and the Western Mediterranean

    Directory of Open Access Journals (Sweden)

    Stos-Gale, Zofia A.

    2010-12-01

    Full Text Available Hundreds of Bronze Age metal artefacts excavated on archaeological sites in Cyprus have been analysed for their lead isotope and elemental composition in the Isotrace Laboratory, University of Oxford, in the years 1982-2002. In parallel, but in particular after 1995, hundreds of samples of minerals and slags collected from the mines and smelting sites around the Troodos Mountains were also analysed. Most of the results were published in various articles over the years, but the interpretation of some of the lead isotope data needs a current revision in view of new research conducted in Spain, Sardinia and southern France. It has been known that the lead isotope data for metal artefacts from the Cypriot Bronze Age sites shows that not all of the copper is consistent with origin from the Cypriot ores. In addition, the lead and silver artefacts found there must have been imported, because there are no lead or silver ores on Cyprus. The re-evaluation of the data shows that about 11 % of the analysed metal artefacts are consistent with the origin from the deposits in the Aegean and Turkey, while about 14 % with sources in the Western Mediterranean. This paper discusses in detail the current interpretation of the research into the sources of imported metal found in the Bronze Age context on Cyprus.

    Cientos de objetos de metal de la Edad del Bronce excavados en yacimientos de Chipre han sido analizados para conocer su composición elemental y sus isótopos de plomo en el Isotrace Laboratory de la Universidad de Oxford entre los años 1982 y 2002. Especialmente con posterioridad a 1995 cientos de muestras de minerales y escorias recogidas de minas y sitios de reducción de minerales localizadas en el entorno de las montañas de Troodos también fueron analizadas. La mayoría de los resultados fueron publicados en varios artículos a lo largo del tiempo, pero la interpretación de algunos análisis de isótopos de plomo necesitan de una revisión a

  1. Exposures from thorium contained in thoriated tungsten welding electrodes.

    Science.gov (United States)

    Jankovic, J T; Underwood, W S; Goodwin, G M

    1999-01-01

    Information provided in this article can be used for estimating the radiation dose associated with the use of thoriated tungsten electrodes in tungsten inert gas welding. Area and breathing zone concentrations of 232Th generated by welding and electrode sharpening along with particle size information; isotopic composition of electrodes from two domestic manufacturers and one European manufacturer; and process variables and estimates on the number of thoriated tungsten electrodes manufactured are presented. Past literature is reviewed and compared with the results of this study. Isotopic analysis of a nominal 2% thoriated electrode found 0.6 ppm +/- 0.4 ppm 230Th and less than 0.1 ppm 228Th. Analysis of a ceriated tungsten electrode and a lanthanated tungsten electrode for 232Th found 124 ppm and 177 ppm, respectively. Electrode consumption during welding was primarily the result of tip sharpening. Less than 3% of the weight loss was attributable to the welding process. The in-mask concentration of respirable thorium particulate in the welder's breathing zone was 0.002 x 10(-12) microCi 232Th/mL. The concentration of respirable thorium particulate from electrode sharpening was 1.3 x 10(-12) microCi 232Th/mL. The measured sharpening time was 20 sec per electrode. Estimates of the activity median aerodynamic diameters for the respirable fraction of the welding and electrode sharpening aerosols were 3.5 and 5 microns, respectively, when measured in the breathing zone at 0.3 m (12 inches) from the point of operation. The respirable fraction of the total welding and sharpening aerosols was 45 and 60%. PMID:10386359

  2. The Bronze Age in the Northwestern of Iberian Peninsula: an analysis from funerary practices

    Directory of Open Access Journals (Sweden)

    Bettencourt, Ana M. S.

    2010-06-01

    Full Text Available From the analysis of the funerary practices and of their integration in the different chronological-cultural contexts where they develop, the author works out a new interpretation of the mechanism of negotiation of power and the promotion of social identity through the Bronze Age of the NW Iberian Peninsula. When studying an area so wide she distinguishes two great trends in the type and distribution of the funerary architectures throughout the Bronze Age that she associates with different ways of interaction with, and perception of, the world. Thus, she argues that the necropolises of “cloudy” tombs (cists without tumuli, plain graves and pits, located in areas of great agricultural potential and close to the settlements, may have been constructed by sedentary communities, very involved in agricultural activities, with a great sense of territoriality and a great control over, and deep knowledge of, the territory. On the other hand the communities involved with mountain landscapes, eventually more related to cattle and with ways of life that would imply greater mobility, were responsible for the construction of more visible funerary structures, such as small tumuli of megalithic tradition, located away from the settlements. In relation to the social role of the corpse, the author argues for the Early Bronze Age, that, the occupation of new territories, the emergence of a new form of community interaction with the environment and the emergence of new mechanisms of power and legitimacy of the territory were materialized in burial practices and in the social role of some corpses, in copper and gold grave goods. This social role was represented in old and new places. From the Middle Bronze Age she assumes that the corpse loses importance in collective terms and that death becomes more familiar. The new settings of power negotiation and social identity are transferred to other contexts of action more connected with the sphere of the living

  3. Analysis of powdered tungsten carbide hard-metal precursors and cemented compact tungsten carbides using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Novotný, K.; Staňková, A.; Häkkänen, H.; Korppi-Tommola, J.; Otruba, V.; Kanický, V.

    2007-12-01

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the direct analysis of powdered tungsten carbide hard-metal precursors and cemented tungsten carbides. The aim of this work was to examine the possibility of quantitative determination of the niobium, titanium, tantalum and cobalt. The investigated samples were in the form of pellets, pressed with and without binder (powdered silver) and in the form of cemented tungsten carbides. The pellets were prepared by pressing the powdered material in a hydraulic press. Cemented tungsten carbides were embedded in resin for easier manipulation. Several lasers and detection systems were utilized. The Nd:YAG laser working at a basic wavelength of 1064 nm and fourth-harmonic frequency of 266 nm with a gated photomultiplier or ICCD detector HORIBA JY was used for the determination of niobium which was chosen as a model element. Different types of surrounding gases (air, He, Ar) were investigated for analysis. The ICCD detector DICAM PRO with Mechelle 7500 spectrometer with ArF laser (193 nm) and KrF laser (248 nm) were employed for the determination of niobium, titanium, tantalum and cobalt in samples under air atmosphere. Good calibration curves were obtained for Nb, Ti, and Ta (coefficients of determination r2 > 0.96). Acceptable calibration curves were acquired for the determination of cobalt (coefficient of determination r2 = 0.7994) but only for the cemented samples. In the case of powdered carbide precursors, the calibration for cobalt was found to be problematic.

  4. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

    International Nuclear Information System (INIS)

    The family of rare earth molybdenum bronzes, reduced ternary molybdates of composition LnMo16O44, was synthesized and a detailed structural study carried out. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO3-type Mo8O36 structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μB moments on each Mo. We suggest that the Mo8O36 units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal. - Graphical abstract: LnMo16O44 phases comprise corner sharing tetrahedral and octahedral molybdenum ions. The MoO6 octahedra form Mo8O36 units that are well separated and act like pseudo-atoms, accommodating 11 electrons each. - Highlights: • Single crystal X-ray diffraction refinements of LnMo16O44 single crystals for Ln=Ce, Pr, Nd, Tb, Dy and Ho. • DFT calculations based on LaMo16O44. • [Mo8O36] units behaving as superatoms with a net magnetic moment of 1 µB. • Bronze structure containing equal number of molybdenum tetrahedra and octahedral

  5. High-performance aqueous asymmetric supercapacitor based on carbon nanofibers network and tungsten trioxide nanorod bundles electrodes

    International Nuclear Information System (INIS)

    The demand for high-performance energy storage devices such as supercapacitors and lithium-ion batteries has been increasing to meet the application requirements of renewable energy systems. Here, high energy density aqueous asymmetric supercapacitor (ASC) is assembled based on carbon nanofibers (CNF) network positive electrode and tungsten trioxide (WO3) nanorod bundles negative electrode. Polyaniline-based CNF are prepared by direct carbonization of polyaniline nanofibers. WO3 nanorod bundles are synthesized via a simple sodium chloride assisted hydrothermal process. The CNF//WO3 ASC device operates with a voltage of 1.6 V and achieved a high energy density of 35.3 Wh kg−1 at a power density of 314 W kg−1. Furthermore, the device shows an excellent cycling performance with capacitance retention of 88% after 1000 cycles

  6. Alloy characterization of a 7th Century BC archeological bronze vase — Overcoming patina constraints using Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Manso, M. [Laboratório de Instrumentação, Engenharia Biomédica e Fisica da Radiação (LIBPhys-UNL), Departamento de Fisica, Faculdade de Ciências e Tecnologias, Universidade Nova de Lisboa, 2829-516 Monte da Caparica (Portugal); Faculdade de Belas-Artes da Universidade de Lisboa, Largo da Academia Nacional de Belas-Artes, 1249-058 Lisboa (Portugal); Schiavon, N. [Hercules Laboratory, University of Évora, Palácio do Vimioso,Largo Marquês de Marialva 8, 7000-809 Évora Portugal (Portugal); Queralt, I. [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabaris s/n, 08028 Barcelona (Spain); Arruda, A.M. [Centro de Arqueologia da Universidade de Lisboa (UNIARQ), Alameda da Universidade, 1600-214 Lisboa (Portugal); Sampaio, J.M. [BioISI — Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa (Portugal); Brunetti, A., E-mail: brunetti@uniss.it [Department of Political Science and Communication, University of Sassari, Via Piandanna 2, 07100 Sassari (Italy)

    2015-05-01

    In this work we evaluate the composition of a bronze alloy using X-ray fluorescence spectrometry (XRF) and Monte Carlo (MC) simulations. For this purpose, a 7th Century BC archeological vase from the SW Iberian Peninsula, displaying a well formed corrosion patina was analyzed by means of a portable X-ray fluorescence spectrometer. Realistic MC simulations of the experimental setup were performed with the XRMC code package which is based on an intensive use of variance-reduction techniques and uses XRAYLIB a constantly updated X-ray library of atomic data. A single layer model was applied for simulating XRF of polished/pristine bronze whereas a two-or-three-layer model was developed for bronze covered respectively by a corrosion patina alone or coupled with a superficial soil derived crust. These simulations took into account corrosion (cerussite (PbCO{sub 3}), cuprite (Cu{sub 2}O), malachite (Cu{sub 2}CO{sub 3}(OH){sub 2}), litharge (PbO)) and soil derived products (goethite (FeO(OH)) and quartz (SiO{sub 2})) identified by means of X-ray diffraction and Raman micro analytical techniques. Results confirm previous research indicating that the XRF/Monte Carlo protocol is well suited when a two-layered model is considered, whereas in areas where the patina + soil derived products' crust is too thick, X-rays from the alloy substrate are not able to exit the sample. Quantitative results based on MC simulations indicate that the vase is made of a lead–bronze alloy: Mn (0.2%), Fe (1.0%), Cu (81.8%), As (0.5%), Ag (0.6%), Sn (8.0%) and Pb (8.0%). - Highlights: • We study an archeological bronze vase with patina corrosion using XRF spectrometry. • The experimental setup is modeled using Monte Carlo (MC) simulations. • Combining MC simulations with XRF it is possible to derive concentrations. • We demonstrated that this is possible without removing the patina.

  7. Thermal reaction of SiC films with tungsten and tungsten-rhenium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roger, J.; Le Petitcorps, Y. [Univ Bordeaux 1, Lab Composites Thermostruct, CNRS-SAFRAN-CEA-UB1, UMR 5801, F-33600 Pessac, (France); Roger, J.; Audubert, F. [CEA Cadarache, DEN/DEC/SPUA/LTEC, F-13108 St Paul Les Durance, (France)

    2008-07-01

    Solid-state reactions between SiC films and W-xRe (x = 0, 5 and 25 at%) substrates on thermal annealing between 1673 K and 1873 K for various durations have been investigated. SiC coatings were deposited on metallic wires by hot filament chemical vapour deposition (HFCVD) from a gas mixture of tetramethyl-silane (TMS) and hydrogen at 1373 K under normal pressure. The interface zones were characterized using scanning electron and optical microscopies, X-ray diffraction and electron microprobe microanalysis. All analyses reveal that SiC reacts with substrates. Various metal silicides and carbides were formed in layered reaction and the presence of these phases was confirmed by electron probe microanalysis. The effects of rhenium on the reactivity were established by the determination of growth kinetics deducted from the thicknesses of reaction zones as a function of annealing time. It has been found that an increase in the diffusion kinetics and activation energy with the quantity of rhenium in the tungsten wire. (authors)

  8. Pitfalls of tungsten multileaf collimator in proton beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Moskvin, Vadim; Cheng, Chee-Wai; Das, Indra J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202 (United States) and Indiana University Health Proton Therapy Center (Formerly Midwest Proton Radiotherapy Institute), Bloomington, Indiana 47408 (United States)

    2011-12-15

    Purpose: Particle beam therapy is associated with significant startup and operational cost. Multileaf collimator (MLC) provides an attractive option to improve the efficiency and reduce the treatment cost. A direct transfer of the MLC technology from external beam radiation therapy is intuitively straightforward to proton therapy. However, activation, neutron production, and the associated secondary cancer risk in proton beam should be an important consideration which is evaluated. Methods: Monte Carlo simulation with FLUKA particle transport code was applied in this study for a number of treatment models. The authors have performed a detailed study of the neutron generation, ambient dose equivalent [H*(10)], and activation of a typical tungsten MLC and compared with those obtained from a brass aperture used in a typical proton therapy system. Brass aperture and tungsten MLC were modeled by absorber blocks in this study, representing worst-case scenario of a fully closed collimator. Results: With a tungsten MLC, the secondary neutron dose to the patient is at least 1.5 times higher than that from a brass aperture. The H*(10) from a tungsten MLC at 10 cm downstream is about 22.3 mSv/Gy delivered to water phantom by noncollimated 200 MeV beam of 20 cm diameter compared to 14 mSv/Gy for the brass aperture. For a 30-fraction treatment course, the activity per unit volume in brass aperture reaches 5.3 x 10{sup 4} Bq cm{sup -3} at the end of the last treatment. The activity in brass decreases by a factor of 380 after 24 h, additional 6.2 times after 40 days of cooling, and is reduced to background level after 1 yr. Initial activity in tungsten after 30 days of treating 30 patients per day is about 3.4 times higher than in brass that decreases only by a factor of 2 after 40 days and accumulates to 1.2 x 10{sup 6} Bq cm{sup -3} after a full year of operation. The daily utilization of the MLC leads to buildup of activity with time. The overall activity continues to increase

  9. Thermal shock behaviour of different tungsten grades under varying conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wirtz, Oliver Marius

    2012-07-19

    Thermonuclear fusion power plants are a promising option to ensure the energy supply for future generations, but in many fields of research enormous challenges have to be faced. A major step on the way to the prototype fusion reactor DEMO will be ITER which is build in Cadarache, southern France. One of the most critical issues is the field of in-vessel materials and components, in particular the plasma facing materials (PFM). PFMs that will be used in a device like ITER have to withstand severe environmental conditions in terms of steady state and transient thermal loads as well as high particle fluxes such as hydrogen, helium and neutrons. Candidate wall materials are beryllium, tungsten and carbon based materials like CFC (carbon fibre composite). Tungsten is the most promising material for an application in the divertor region with very severe loading conditions and it will most probably also be used as PFM for DEMO. Hence, this work focuses on the investigation of the thermal shock response of different tungsten grades in order to understand the damage mechanisms and to identify material parameters which influence this behaviour under ITER and DEMO relevant operation conditions. Therefore the microstructure and the mechanical and thermal properties of five industrially manufactured tungsten grades were characterised. All five tungsten grades were exposed to transient thermal events with very high power densities of up to 1.27 GWm{sup -2} at varying base temperatures between RT and 600 C in the electron beam device JUDITH 1. The pulse numbers were limited to a maximum of 1000 in order to avoid immoderate workload on the test facility and to have enough time to cover a wide range of loading conditions. The results of this damage mapping enable to define different damage and cracking thresholds for the investigated tungsten grades and to identify certain material parameters which influence the location of these thresholds and the distinction of the induced

  10. Development of sodium technology

    International Nuclear Information System (INIS)

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, τc = δ·g-0.83·10(3570/TNa-3.34), in 400-500 deg C of liquid sodium atmosphere. The characteristics of pressure propagation and gas flow, and pressure

  11. Development of sodium technology

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Tai; Nam, H. Y.; Choi, Y. D. [and others

    2000-05-01

    The objective of present study is to produce the experimental data for development and verification of computer codes for development of LMR and to develop the preliminary technologies for the future large scale verification experiments. A MHD experimental test loop has been constructed for the quantitative analysis of the effect of magnetic field on the sodium flow and experiments are carried out for three EM pumps. The previous pressure drop correlations are evaluated using the experimental data obtained from the pressure drop experiment in a 19-pin fuel assembly with wire spacer. An dimensionless variable is proposed to describe the amplitude and frequency of the fluctuation of free surface using the experimental data obtained from free surface experimental apparatus and an empirical correlation is developed using this dimensionless variable. An experimental test loop is constructed to measure the flow characteristics in IHX shell side and the local pressure drop in fuel assembly, and to test the vibration behaviour of fuel pins due to flow induced vibration. The sodium two-phase flow measuring technique using the electromagnetic flowmeter is developed and the sodium differential pressure drop measuring technique using the method of direct contact of sodium and oil is established. The work on the analysis of sodium fire characteristics and produce data for vlidation of computer code is performed. Perfect reopen time of self plugged leak path was observed to be about 130 minutes after water leak initiation. Reopen shape of a specimen appeared to be double layer of circular type, and reopen size of this specimen surface was about 2mm diameter on sodium side. In small water leakage experiments, the following correlation equation about the reopen time between sodium temperature and initial leak rate was obtained, {tau}{sub c} = {delta}{center_dot}g{sup -0.83}{center_dot}10{sup (3570/T{sub Na}-3.34)}, in 400-500 deg C of liquid sodium atmosphere. The characteristics

  12. Holes in teeth - Dental caries in Neolithic and Early Bronze Age populations in Central Germany.

    Science.gov (United States)

    Nicklisch, Nicole; Ganslmeier, Robert; Siebert, Angelina; Friederich, Susanne; Meller, Harald; Alt, Kurt W

    2016-01-01

    This study provides diachronic insight into the epidemiology of carious defects in teeth of Neolithic and Early Bronze Age populations in Central Germany over a period of 4000 years. The data were retrieved from skeletal remains uncovered at 21 sites throughout the Middle Elbe-Saale region (MES), comprising a total of 494 individuals with preserved teeth. The data generated were examined for age- and sex-related differences in order to gain information about the dietary habits and socio-economic structures of the period with the goal of identifying potential diachronic changes. The results indicated that dietary habits changed over the course of the Neolithic period: the prevalence of caries significantly decreased between the Early and Late Neolithic. The adults from the Early Neolithic sample, particularly those from the LBK bore the highest rate of caries. This highlights the essential importance of cereals in the diet of the early farmers in the Middle Elbe-Saale region. As time went on, meat and dairy products became more and more important, which had a positive impact on dental health. The data also show sex-specific differences: women were more often affected by caries than men and female jaws also generally exhibited greater numbers of carious teeth than their male counterparts. Dental health is a reflection of both biological factors and of economic and sociocultural structures. PMID:25765291

  13. Astronomical Interpretation of the Signs on the Vessel of the Bronze Age (Central Donbass)

    CERN Document Server

    Vodolazhskaya, Larisa N; Nevsky, Mikhail Yu

    2015-01-01

    The article presents the results of multidisciplinary study carried out with the help of archaeological and astronomical methods. The aim of the study was to analyze and interpret the signs - elements of the composition, incised on the outer side surface of the vessel of the Late Bronze Age, owned to Srubna culture and discovered near the Staropetrovsky village in the northeast of the Donetsk region. The measurements and astronomical calculations revealed that all signs have astronomical meaning. Fourray star has been interpreted as the star Sirius. The sign polyline has been interpreted as an analog of graphic of equation of time in which the testimony of a water clock correspond with average solar time, and the testimony of a sundial - the true solar time. Sign wheel has been interpreted as a complex of lines, reflecting the regularity changing the direction of the shadows from the gnomon at sunset at the equinoxes and solstices. The sign thin polyline has been interpreted as a symbol of change of height of...

  14. Effect of Annealing Atmosphere on the Mechanical Property of Free-cutting Phosphor Bronze Alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The present work is focused on the influence of annealing atmosphere on the microstructure and mechanical property of free-cutting phosphor bronze alloy. The annealing of the alloy was conducted in the three kinds of annealing atmosphere such as air, vacuum and nitrogen. After annealing, a discernable difference in recystallized grain size and lead particle size was not appeared with different annealing atmosphere. The tensile strength of the alloy annealed in air or nitrogen atmosphere was higher than that of those annealed in vacuum atmosphere. In thecase of the alloy annealed in vacuum atmosphere, the mechanical strength was reduced by vaporization of zinc. In the case of annealing in nitrogen and in air atmosphere, the sweating of lead was occurred. However, the inverse segregation of lead was suppressed by copper oxide layer on the surface annealed in air. This copper oxide layer leads to a decrease of the yield during fabrication process. Therefore, annealing of the alloy in nitrogen atmosphere is favorable in terms of the mechanical strength and yield.

  15. Computed tomography of a medium size Roman bronze statue of Cupid

    Energy Technology Data Exchange (ETDEWEB)

    Bettuzzi, M.; Brancaccio, R. [University of Bologna, Department of Physics and Astronomy, Bologna (Italy); Casali, F.; Morigi, M.P. [University of Bologna, Department of Physics and Astronomy, Bologna (Italy); Centro Fermi, Rome (Italy); Carson, D.; Chiari, G. [Getty Conservation Institute, Los Angeles, CA (United States); Maish, J. [The J. Paul Getty Museum, Los Angeles, CA (United States)

    2015-01-14

    Diagnostics based on X-ray computed tomography (CT) are becoming increasingly important, not only in the medical field but in industry and cultural heritage. CT devices typical for medical applications, however, can seldom be used on art objects because both they are not easily transportable and they often present high X-ray absorption. It is therefore necessary to make use of portable instrumentation and/or to develop tomographic systems optimized to the characteristics of the objects under examination. This work describes the computed tomography of a first century A.D. Roman bronze statue of Cupid (96.AB.53) in the collection of the J. Paul Getty Museum, within the collaborative framework between the Getty Conservation Institute and the Department of Physics and Astronomy (DIFA) of the University of Bologna (Italy). The tomography performed at the Getty facilities employed a 450 kV X-ray tube and a detection system developed at DIFA. The study highlighted the casting and construction techniques used by Roman foundry workers and provided information on the status of conservation of the statue. A 3D virtual reconstruction allowed the user to define different cross-sections enabling the study of the internal features. (orig.)

  16. The water clock of the Bronze Age (Northern Black Sea Coast)

    CERN Document Server

    Vodolazhskaya, Larisa N; Nevsky, Mikhail Yu

    2015-01-01

    In the article presents the results of the multidisciplinary study conducted with the help of archaeological, physical and astronomical methods. The aim of the study was to analyze and interpret marks and drawings applied to the surface of the vessel of the Bronze Age (Srubna culture) found near the Staropetrovsky village (Donetsk region, Ukraine) near the border between the Donetsk and Lugansk regions. The carried out calculations and measurements possible to prove that staropetrovsky vessel is the most ancient water clock, discovered on the territory of Europe, and have approximately the same age as the oldest known ancient Egyptian water clock. Such vessels - water clocks were needed for Srubna population to mark sundial, which had recently been discovered in the Northern Black Sea Coast. Based on the analysis of marks on the outside of the vessel, it was revealed that Staropetrovsky vessel is unique ancient complex device for measuring time and at the same time using a water clock, and with the help of a ...

  17. Mitochondrial DNA analysis of Bronze Age horses recovered from Chifeng region, Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Cai Dawei; Han Lu; Xie Chengzhi; Li Shengnan; Zhou Hui; Zhu Hong

    2007-01-01

    In this study, mitochondrial DNA (mtDNA) analysis was carried out on 9 Bronze Age horses recovered from Dashanqian and Jinggouzi archaeological sites in Chifeng region, Inner Mongolia, China to explore the origin of Chinese domestic horses. Both mtDNA 16S rRNA gene and control region (D-loop) fragments of ancient horses were amplified and sequenced. The analysis of the highly conservative 16S rRNA gene sequences indicated that the burial environment of Chifeng region is suitable for the preservation of ancient DNA (aDNA). Combing 465 mtDNA D-loop sequences representing different breeds from East Asia, Central Asia, Near East and Europe, we constructed a phylogenetic network to investigate the relationship between ancient and modern horses. The phylogenetic network showed that the 9 horses were distributed into different modem horse clusters which were closely related to them representing a certain ge-ographical distribution. Our results showed that the maternal genetic line of the ancient horses in Chifeng region was highly diversified,which contributed to the gene pool of modern domestic horses and suggested a complex origin of domestic horses in China.

  18. Leather material found on a 6th B.C. Chinese bronze sword: A technical study

    Science.gov (United States)

    Luo, Wugan; Si, Yi; Wang, Hongmin; Qin, Ying; Huang, Fengchun; Wang, Changsui

    2011-09-01

    During July to November, 2006, an important archaeological excavation was conducted in Yun country, Hubei province, southern China. Chinese archaeologists found some remnant of leather materials, covered with red pigments, on a 6th century B.C. Chinese bronze sword. To understand the technology/ies that may have been utilized for manufacturing the leathers, a combined of Raman spectroscopy, FT-IR and XRF was thus applied to the remnant of leather materials. Raman analyses showed that red pigment on the leather was cinnabar (HgS). FT-IR and XRF analyses indicated that the content of some elements, such as Ca (existing as CaCO 3) and Fe (existing as Fe 2O 3), were much higher than those in the surrounding grave soil. The results inferred an application of lime depilation and retting, and the Fe-Al compound salt as tanning agent. And it was furthermore implicated that the Fe-Al salt tanning technique had been developed in the middle and late Spring and Autumn Period of China.

  19. The examination, analysis and conservation of a bronze Egyptian Horus statuette

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A. [Conservation Department, Ditsong: National Museum of Cultural History, PO Box 28088, Sunnyside, Pretoria 0132 (South Africa); Botha, H. [South African Institute for Objects Conservation, PO Box 122, Joubertina 6410 (South Africa); Beer, F.C. de, E-mail: frikkie.debeer@necsa.co.za [Radiation Science, Necsa, PO Box 582, Pretoria 0001 (South Africa); Ferg, E. [Department of Chemistry, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2011-09-21

    The production techniques, corrosive deterioration, conservation and questions regarding authenticity of a small Egyptian bronze statuette of the Child Horus (in the collection of the Ditsong: National Museum of Cultural History in Pretoria) was scientifically examined and analysed. The statuette dates to Egypt's 12th Dynasty. When the statuette was damaged, it was considered the appropriate time to obtain valuable information about its history and background through scientific research. Neutron tomography (NT), a relatively new non-destructive technique (NDT) to the South African R and D community to study museum objects, was applied to perform this research. The results from NT were supported by additional tests done through XRF and XRD analyses of samples taken from the damaged statuette. Results revealed that the lost-wax method was used in the manufacturing process. The extent of the restoration and materials used can be verified and as a result the deterioration of the object can now be monitored. This paper describes in detail the analytical techniques used in the study and how it contributed to the conservation of the statuette and its authenticity.

  20. Canine transposition in prehistoric Pakistan: Bronze Age and Iron Age case reports.

    Science.gov (United States)

    Lukacs, J R

    1998-10-01

    This report documents two prehistoric cases of canine-first premolar transposition (Mx.C.P1) from the Indo-Pakistan subcontinent. Recent discussion of the etiology of canine transposition and reports of high prevalence for the condition in modern India accentuate the significance of the ancient cases reported there. Case 1 is from the Iron Age site of Sarai Khola in northern Pakistan (1000 BC). The specimen, an adult female, 25 to 30 years of age at death, exhibits unilateral Mx.C.P1 transposition on the left side. The condition is associated with a barrel-shaped maxillary left third molar in an otherwise normal and healthy maxillary dental arch. Case 2 is from the Bronze Age urban site of Harappa (2500 BC), an important center of the Indus Valley Civilization. In this specimen, an adult female, transposition is bilateral, resulting in displacement of premolars and large diastemata between the maxillary lateral incisors and first premolars. Bilateral agenesis of maxillary third molars and rotation of maxillary and mandibular teeth occur with transposition in this specimen. In neither case are the lateral incisors reduced in size, peg-shaped, or congenitally absent. This report of Mx.C.P1 transposition in prehistoric times is significant because it provides historical documentation for the female predilection of the trait and establishes its co-occurrence with specific dental variants, such as agenesis, reduction, and rotation of teeth. PMID:9770107

  1. Dental paleopathology and agricultural intensification in south Asia: new evidence from Bronze Age Harappa.

    Science.gov (United States)

    Lukacs, J R

    1992-02-01

    Patterns of dental disease among Bronze Age people of the Indus Valley Civilization are currently based on early and incomplete reports by non-specialists. This deficiency precludes accurate diachronic analysis of dental disease and its relationship with increasing agriculturalism in the Indian subcontinent. The objective of this paper is to document prevalence of dental disease at Harappa (2500-2000 B.C.), Punjab Province, Pakistan, comparatively evaluate the Harappan dental pathology profile, and use these data to assess theories regarding the dental health consequences of increasingly intensive agricultural dependence. Pathological conditions of the dentition included in the study are abscesses, ante-mortem tooth loss (AMTL), calculus, caries, hypoplasia, hypercementosis, pulp chamber exposure, and alveolar resorption. The Harappan dentition exhibits a dental pathology profile typical of a population whose subsistence base is agriculture. Dental caries at Harappa are present in 6.8% (n = 751) of the teeth and 43.6% (n = 39) of the more completely preserved dental specimens. The use of a caries correction factor is recommended to permit an estimate of caries induced AMTL in calculating the caries prevalence. All dental lesions are present at higher rates in this Harappan study sample than were reported in previous investigations, and important differences in prevalence of dental disease occur between the genders. Prevalence of dental disease increases in the greater Indus Valley as subsistence becomes more intensive and as food preparation and storage technology becomes more efficient. PMID:1543240

  2. Genetic evidence for an origin of the Armenians from Bronze Age mixing of multiple populations.

    Science.gov (United States)

    Haber, Marc; Mezzavilla, Massimo; Xue, Yali; Comas, David; Gasparini, Paolo; Zalloua, Pierre; Tyler-Smith, Chris

    2016-06-01

    The Armenians are a culturally isolated population who historically inhabited a region in the Near East bounded by the Mediterranean and Black seas and the Caucasus, but remain under-represented in genetic studies and have a complex history including a major geographic displacement during World War I. Here, we analyse genome-wide variation in 173 Armenians and compare them with 78 other worldwide populations. We find that Armenians form a distinctive cluster linking the Near East, Europe, and the Caucasus. We show that Armenian diversity can be explained by several mixtures of Eurasian populations that occurred between ~3000 and ~2000 bce, a period characterized by major population migrations after the domestication of the horse, appearance of chariots, and the rise of advanced civilizations in the Near East. However, genetic signals of population mixture cease after ~1200 bce when Bronze Age civilizations in the Eastern Mediterranean world suddenly and violently collapsed. Armenians have since remained isolated and genetic structure within the population developed ~500 years ago when Armenia was divided between the Ottomans and the Safavid Empire in Iran. Finally, we show that Armenians have higher genetic affinity to Neolithic Europeans than other present-day Near Easterners, and that 29% of Armenian ancestry may originate from an ancestral population that is best represented by Neolithic Europeans. PMID:26486470

  3. Aerobic swimming performance of juvenile largemouth bronze gudgeon (Coreius guichenoti) in the Yangtze River.

    Science.gov (United States)

    Tu, Zhiying; Li, Liping; Yuan, Xi; Huang, Yingping; Johnson, David

    2012-06-01

    Largemouth bronze gudgeon (Coreius guichenoti), a fish species once abundant in the Yangtze River, has been rapidly declining in recent years. One important factor, among many, is the interruption of the free-flowing rivers by dams. To obtain data that can be applied to the design of an effective fishway for C. guichenoti and other species in the fish community, a laboratory study of juvenile C. guichenoti's swimming ability and energetics was conducted in a flume-type respirometer equipped with a high-speed video camera system to record swimming behavior. The critical swimming speed (Ucrit ), standard metabolic rate (SMR), and maximum metabolic rate (MO2,max ) were determined during steady swimming at four water temperatures (10, 15, 20, and 25°C). A power function accurately describes the relationship between oxygen consumption rate (MO2 ) and swimming speed (U) at the four temperatures. The Ucrit , SMR, MO2,max , and metabolic scope increased with increasing temperature. The relationship between cost of transport (COT) and U was characteristically inverse bell-shaped, with minimum COT at Uopt = 4.5-5.0 body lengths per second (bl sec(-1)). This investigation provides data on the swimming ability of C. guichenoti that will add to the basic science required for fishway design.

  4. The questionable contribution of the Neolithic and the Bronze Age to European craniofacial form.

    Science.gov (United States)

    Brace, C Loring; Seguchi, Noriko; Quintyn, Conrad B; Fox, Sherry C; Nelson, A Russell; Manolis, Sotiris K; Qifeng, Pan

    2006-01-01

    Many human craniofacial dimensions are largely of neutral adaptive significance, and an analysis of their variation can serve as an indication of the extent to which any given population is genetically related to or differs from any other. When 24 craniofacial measurements of a series of human populations are used to generate neighbor-joining dendrograms, it is no surprise that all modern European groups, ranging all of the way from Scandinavia to eastern Europe and throughout the Mediterranean to the Middle East, show that they are closely related to each other. The surprise is that the Neolithic peoples of Europe and their Bronze Age successors are not closely related to the modern inhabitants, although the prehistoric/modern ties are somewhat more apparent in southern Europe. It is a further surprise that the Epipalaeolithic Natufian of Israel from whom the Neolithic realm was assumed to arise has a clear link to Sub-Saharan Africa. Basques and Canary Islanders are clearly associated with modern Europeans. When canonical variates are plotted, neither sample ties in with Cro-Magnon as was once suggested. The data treated here support the idea that the Neolithic moved out of the Near East into the circum-Mediterranean areas and Europe by a process of demic diffusion but that subsequently the in situ residents of those areas, derived from the Late Pleistocene inhabitants, absorbed both the agricultural life way and the people who had brought it. PMID:16371462

  5. THE PALEODEMOGRAPHIC PATTERN OF OYLUM HOYUK POPULATION (THE MIDDLE BRONZE AGE, KİLİS

    Directory of Open Access Journals (Sweden)

    Ayşen Açıkkol Yıldırım

    2013-12-01

    Full Text Available In this study skeleton remaining of 72 individuals excavated from Middle Bronze Age layers of Oylum Höyük (mound situated in Kilis province, were studied. Sex and age of skeletons, unearthed between 2007-2012, were determined and life tables of the population were formed. Mortality of infants and children of Oylum population was very high. Death rates were determined as 36.6 % for 0-5 years of age group, 57.75 % for 0-15 years of age group. 34.62 % of infants and children from 0-5 years of age group died before they completed their 1st year. Lifespan of males were longer than females (25 for females, 33 years for males. Average age of adults was 29. Mortality for females was highest in young adult period (18-30 ages however it becomes more prominent at adulthood period (30-45 years in males. Oylum Höyük population has one of the shortest lifespan among ancient Anatolian populations with its very high subadult death ratios. Paleopathological data states that, individuals were exposed to serious stress during growth period and reproductive period is the most dangerous period for females.

  6. Sliding Wear Response of a Bronze Bushing: Influence of Applied Load and Test Environment

    Science.gov (United States)

    Prasad, B. K.

    2012-10-01

    This investigation pertains to the examination of the sliding wear behavior of a leaded-tin bronze bushing under the conditions of varying applied loads and test environments against a steel shaft. The test environment was changed by adding 5% of solid lubricants like talc and lead to an oil lubricant separately as well as in combination; the fraction of the two (solid) lubricants within the solid lubricant mixture was varied in the range of 25-75% in the latter case. The wear performance of the bushing was characterized in terms of the wear rate, frictional heating, and friction coefficient. The increasing load led to deterioration in the wear response, while the addition of the solid lubricant particles produced a reverse effect. Further, an appreciable difference in the wear behavior was not observed when the tests were conducted in the oil plus talc and oil plus lead lubricant mixtures. However, the oil containing lead and talc together brought about a significant improvement in the wear response; best results were obtained in the case of the lubricant mixture consisting of lead and talc together in the ratio of 3:1 in the oil. The observed wear behavior of the samples has been discussed in terms of specific characteristics of various microconstituents. The features of the wear surfaces and subsurface regions further substantiated the wear response and enabled us to understand the operating material removal mechanisms.

  7. Fabricating Superior NiAl Bronze Components through Wire Arc Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Donghong Ding

    2016-08-01

    Full Text Available Cast nickel aluminum bronze (NAB alloy is widely used for large engineering components in marine applications due to its excellent mechanical properties and corrosion resistance. Casting porosity, as well as coarse microstructure, however, are accompanied by a decrease in mechanical properties of cast NAB components. Although heat treatment, friction stir processing, and fusion welding were implemented to eliminate porosity, improve mechanical properties, and refine the microstructure of as-cast metal, their applications are limited to either surface modification or component repair. Instead of traditional casting techniques, this study focuses on developing NAB components using recently expanded wire arc additive manufacturing (WAAM. Consumable welding wire is melted and deposited layer-by-layer on substrates producing near-net shaped NAB components. Additively-manufactured NAB components without post-processing are fully dense, and exhibit fine microstructure, as well as comparable mechanical properties, to as-cast NAB alloy. The effects of heat input from the welding process and post-weld-heat-treatment (PWHT are shown to give uniform NAB alloys with superior mechanical properties revealing potential marine applications of the WAAM technique in NAB production.

  8. Microstructure and properties of an ordered and a disordered ship propeller bronze

    Energy Technology Data Exchange (ETDEWEB)

    Benkisser, G.; Winkel, G. [Rostock Univ. (Germany); Eberlein, J.; Kaps, R. [Mecklenburger Metallguss Waren (Germany)

    2000-07-01

    The purpose of this paper is a presentation of the investigation results on the influence of the chemical composition and the casting conditions on the transformation behaviour, the microstructure and the properties of the complex aluminium bronzes. By the solidification of the melt is produced the bcc high temperature phase {beta}. In dependence on the cooling time the {beta} - phase transforms in several product phases. In the ordered alloy additionally occur an ordering transformation of the {beta} - phase. Both alloys investigated posses in the sand cast state a heterogenous, coarse grained microstructure. The predominant part of the microstructure is the fcc {alpha} - phase. The lamellar quasieutectoid ({alpha} + {kappa}{sub 3}) and several types of {kappa} - segregates are further parts in the microstructure of the ordered alloy. The {gamma}{sub 2} - phase appears not in the microstructure. In the microstructure of the disordered alloy the retained bcc {beta} - phase and also {kappa} - segregates additionaly exist. The mechanical properties of the alloys depend on the chemical composition and the processing, especially on the cast wall thickness, because the thickness determines the cooling time and in connection with it the transformation behaviour and the phase composition, the grain size and the form and distribution of the phases in the microstructure. The ordered alloy has a higher cavitation resistance in comparison to the disordered alloy. (orig.)

  9. High temperature performance of arc-sprayed aluminum bronze coatings for steel

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong-li; LI De-yuan; WANG Shui-yong

    2006-01-01

    The high-temperature oxidation behavior of arc-sprayed aluminum bronze coatings on steel substrate was studied during isothermal exposures in air at 900 ℃. The surface morphologies and interface of the coatings after isothermal oxidation at 900 ℃ for different times were observed. The experiments showed that the coatings on steel substrate were not deteriorated and the substrate was protected well, being exposed to high temperatures up to 900 ℃. The coatings withstood more than ten times thermal shock tests without any coating separation. The thermal expansion coefficient of the coatings was measured, revealing not much difference between it and that of steel substrate. After exposure at high temperature, the coatings were still adhered to steel substrate well.Isothermal mass gain of the coatings at elevated temperature in dry air was measured by means of a thermal balance and the oxidation behavior was evaluated by oxidation kinetic curves, exhibiting the oxidation kinetics curve accorded with a parabolic law.The parabolic rate constant of the oxidation kinetic curve is 1.02× 10-9 g2·cm-4·s-1 for the first 60 min and from 150 min to 2 880 min the constant is 5.1 × 10-12 g2·cm-4·s-1.

  10. Deformation behaviour of a newer tungsten heavy alloy

    International Nuclear Information System (INIS)

    Highlights: → Calculation of activation volume and strain rate sensitivity as a function of strain (from the room temperature tensile test data) has been carried out for the tungsten heavy alloy. → Flow behaviour of the tungsten heavy alloy at room temperature has been studied in detail. → Calculation of strain rate sensitivity index at room temperature and at elevated temperature is carried out from the tensile and compression test data. → Calculation of activation energy of deformation of tungsten heavy alloy is carried out to understand the rate controlling mechanism of deformation. → Study of the matrix flow behaviour at elevated (500-700 deg. C) temperatures is also carried out. - Abstract: The present study attempts to investigate room temperature and high temperature flow behaviour of a tungsten heavy alloy (W-7.10Ni-1.65Fe-0.5Co-0.25Mo alloy). The alloy was deformed under compression at room temperature and elevated temperatures (400-700 deg. C) at different strain rates (1-0.0001 s-1) to observe plasticity under compression loading at these temperatures and strain rates. The alloy showed higher plasticity and positive strain rate sensitivity at room temperature. Samples hardness after 70% deformation at room temperature increased from 3.20 ± 0.14 to 5.08 ± 0.03 GPa. Barreling was observed in room temperature compression tested samples. Microstructure of the alloy after heavy compressive deformation at room temperature showed that severe deformation of W grains took place along a direction at 45 deg. to the direction of applied stress. The alloy showed varying (positive and negative) strain rate sensitivity at elevated temperatures. Samples hardness after 70% deformation at elevated temperatures increased from 3.20 ± 0.14 to 4.60 ± 0.23 GPa. At 600 and 700 deg. C, the specimens failed by shear along the direction which is at an angle 45 deg. to the direction of applied stress. Microstructural evidences indicate that the failure at these

  11. Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten

    International Nuclear Information System (INIS)

    Highlights: ► Deuterium tungsten interaction was simulated using classical molecular dynamic methods. ► Low energy deuterium atoms tend to affix to high temperature tungsten surface. ► Tungsten substrate temperature barely affects the low energy deuterium implantation depth. ► Deuterium bubble formation resulting from near surface super-saturation was predicted. -- Abstract: The interaction between plasma particles and tungsten as plasma facing material is one of the critical issues in successfully using tungsten in Tokamak reactors environment. The deuterium bombardment of monocrystalline tungsten was modeled by molecular dynamics simulation using LAMMPS code and Tersoff type interatomic potential. The deuterium trapping rate, implantation depth, and the stopping time in tungsten at several temperatures ranging from 600 to 2000 K bombarded by 5–100 eV deuterium atoms were simulated. Deuterium bubble formation at near tungsten surface was also studied. Irradiated monocrystalline tungsten became amorphous state prior to deuterium cluster formation, and gas bubbles were observed in the 600, 900, and 1200 K tungsten samples. The formation of gas bubbles were caused by the near surface deuterium super-saturation region and the subsequent plastic deformation induced by the local high gas pressure

  12. Stability of the anodic growth porous tungsten oxide in different solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Y.; Yam, F. K.; Hassan, Z. [Nano-Optoelectronic Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-05-15

    This article presents the study of the stability of the anodic growth porous tungsten oxide (WO{sub 3}) film in different solutions. As-anodized films are relatively stable in acidic electrolytes like sulphuric acid (H{sub 2}SO{sub 4}), hydrochloric acid (HCl) but not in oxalic acid. In higher pH solution, rate of dissolution of the WO{sub 3} film is higher. Annealing at 400 °C for 2 h transform the as-grown sample from amorphous phase to the crystalline phase and this significantly improve the stability of the film in high pH solution. Photocurrent measurements reveal that there is no significant difference of the electrolyte used (0.5 M H{sub 2}SO{sub 4}, 0.33 M H{sub 3}PO{sub 4}, 0.1 M sodium sulfate (Na{sub 2}SO{sub 4})) on the photocurrent. As-annealed films exhibit good stablility for the long photoelectrochemical (PEC) measurements (1700 s) in 0.5 M H{sub 2}SO{sub 4} and 0.1 M Na{sub 2}SO{sub 4}. There is no effect on the photocurrent for the variation of the concentration of the acidic solution (H{sub 2}SO{sub 4}). However, lower photocurrent was obtained as the concentration of Na{sub 2}SO{sub 4} was increased.

  13. Potential of 5-methyl 1-H benzotriazole to suppress the dissolution of α-aluminum bronze in sulfide-polluted salt water

    Energy Technology Data Exchange (ETDEWEB)

    Nazeer, Ahmed Abdel; Ashour, E.A. [National Research Centre, Electrochemistry Laboratory, Dokki, Cairo 12622 (Egypt); Allam, Nageh K., E-mail: nageh.allam@aucegypt.edu [National Research Centre, Electrochemistry Laboratory, Dokki, Cairo 12622 (Egypt); Energy Materials Laboratory, Physics Department, School of Sciences and Engineering, The American University in Cairo, P.O. Box 74, New Cairo 11835 (Egypt)

    2014-03-01

    This work investigates the inhibition effect of 5-methyl 1-H benzotriazole (MBT) on the dissolution behavior of α-aluminum bronze in clean and sulfide-polluted salt water using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and scanning electron microscopy (SEM) techniques. The inhibition efficiency increases with the increasing MBT concentration and decreases with the increasing temperature. The adsorption process of MBT is spontaneous and follows Langmuir adsorption isotherm model. MBT possesses excellent inhibiting effect for the corrosion of α-Al-bronze, which acts as a mixed type inhibitor. Thermodynamic and kinetic parameters for the adsorption process were determined. The presence of sulfide ions (2 ppm) decreases the inhibition efficiency of MBT against the corrosion of Al-bronze alloy in chloride solutions from 94.7% to 89% as also confirmed via SEM images. The results obtained from the different techniques were in good agreement, which prove the validity of these tools in the measurements of the tested inhibitor. - Highlights: • MBT is an excellent mixed corrosion inhibitor for bronze. • There is a competitive adsorption between MBT and sulfide ions to adsorb on bronze surface. • The adsorption of MBT is spontaneous and follows Langmuir model. • CPE decreases significantly with the increasing MBT concentration.

  14. The effect of low-dose neutron irradiation on mechanical properties, electrical resistivity and fracture of NiAl bronze for ITER

    International Nuclear Information System (INIS)

    Nickel-aluminum bronze is a candidate material for several applications for ITER in-vessel components such as divertor and blanket attachments and remote handling equipment. This paper presents the first results of an experimental investigation of the effect of neutron irradiation on mechanical properties, fracture characteristics and electrical resistivity of NiAl bronze. Specimens of NiAl bronze were irradiated at 150 oC and 300 oC to doses of 10-3; 10-2; 0.7 * 10-1 dpa in the RBT-6 reactor (Φt therm/Φt fast ∼ 1) in Dimitrovgrad. It was shown that irradiation at 150 oC leads to minor changes of tensile properties, whereas irradiation at 300 oC results in significant loss of ductility at damage dose of 0.07 dpa. The change of electrical resistively of NiAl bronze is low, ∼3% at the maximum dose studied. The reasons for the high-radiation resistance of NiAl bronze in comparison with copper and copper alloys are discussed

  15. 古滇王国青铜器的造型艺术研究%Research on Bronze Aesthetic Art of the Ancient Dian Kinadom

    Institute of Scientific and Technical Information of China (English)

    张吉洪

    2012-01-01

    Bronze art from the Ancient Dian Kingdom of Yunnan is an especially charming segment of China' s ancient bronze culture. Ancient Dian bronze art is famous for its outstanding aesthetics and intricate details. The firm conceptualization and practicality underpinning its stunning appearance has put it in a class of its own. The Ancient Dian had rendered numerous aspects of their civilization' s culture on bronze art -- farming, livestock, textiles, hunting and war, among others. They have created their animated history on bronze.%云南古滇青铜器的艺术魅力,是中华民族古代青铜文化中的一支夺目的奇葩,以其造型精美奇特、纹饰细腻丰富闻名于世,其写实性之强,构思巧妙,独树一帜。滇国的先民们把当时耕作、畜牧、纺织、狩猎、战争等各种社会生活场景凝聚在青铜器上,用自己的双手铸造了一部生动的青铜史诗。

  16. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  17. Too Much Sodium

    Centers for Disease Control (CDC) Podcasts

    2012-02-07

    This podcast is based on the February 2012 CDC Vital Signs report. Ninety percent of Americans age two and older eat too much sodium which can increase your risk for high blood pressure and often leads to heart disease and stroke, two leading causes of death in the US. Learn several small steps you can take to reduce the amount of sodium in your diet.  Created: 2/7/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 2/7/2012.

  18. Development of positron annihilation spectroscopy for characterizing neutron irradiated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    C.N. Taylor; M. Shimada; D.W. Akers; M.W. Drigert; B.J. Merrill; Y. Hatano

    2013-05-01

    Tungsten samples (6 mm diameter, 0.2 mm thick) were irradiated to 0.025 and 0.3 dpa with neutrons in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Samples were then exposed to deuterium plasma in the tritium plasma experiment (TPE) at 100, 200 and 500ºC to a total fluence of 1 x 1026 m-2. Nuclear reaction analysis (NRA) and Doppler broadening positron annihilation spectroscopy (DB-PAS) were performed at various stages to characterize damage and retention. We present the first known results of neutron damaged tungsten characterized by DB-PAS in order to study defect concentration. Two positron sources, 22Na and 68Ge, probe ~58 µm and through the entire 200 µm thick samples, respectively. DB-PAS results reveal clear differences between the various irradiated samples. These results, and the calibration of DB-PAS to NRA data are presented.

  19. Modifying effect of tungsten on vacuum condensates of iron

    Science.gov (United States)

    Barmin, A. E.; Sobol', O. V.; Zubkov, A. I.; Mal'tseva, L. A.

    2015-07-01

    Laws of the structure formation, as well as the strength properties and thermal stability of vacuum condensates of the Fe-W system have been studied. It has been found that the alloying of iron foils with tungsten to 1 at % makes it possible to disperse the grained structure of the condensates to nanometric dimensionality and to markedly enhance their strength properties and recrystallization temperature. Thus, the foils containing ˜0.8% tungsten and grains of about 50 nm in size exhibit the hardness 5.5 GPa and recrystallization temperature 800°C. These results can be used to devise compositions of the steels designed for subsequently obtaining high-strength and thermostable nanostructural states.

  20. Delamination of LPD tungsten films by residual stress

    International Nuclear Information System (INIS)

    Thin tungsten films have been deposited on sapphire and glass substrates using laser photolytic deposition from a tungsten hexa-flouride precursor. This paper reports on failure of the films which is caused by the presence of large residual stresses (1.5 GPa). Compressive and tensile stresses are found at different stages of film growth and either may be responsible for delamination. Early compression is caused by oxidation and impurity influenced intrinsic stress. Tensile stress occurs with microstructural changes but it is not maintained with film growth. Large stress gradients, indicative of up to 0.75-1.2% lattice strain difference across the film, are found through both compressive and tensile films and are not explained