Effect of structural packing on the luminescence properties in tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba)

Energy Technology Data Exchange (ETDEWEB)

Yin Xin; Shi Liu [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wei Ang, E-mail: iamawei@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays, 9 Wenyuan Road, Nanjing 210046 (China); Wan Dongyun; Wang Yaoming [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Huang Fuqiang, E-mail: huangfq@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2012-08-15

Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) were successfully synthesized, and the luminescence properties were investigated. Among the three compounds, Ca{sub 2}KNb{sub 5}O{sub 15} showed an obviously broad band of host luminescence at 460 nm with exciting at 269 nm. By doping Eu{sup 3+} into the M sites, Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} displayed strong red emission from Eu{sup 3+} ions characteristic transitions, nearly four times higher than Sr{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} and seven times higher than Ba{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+}. Crystal packing factor (PF) was introduced to account for this luminescence difference, lower PF being correlated to higher luminescence intensity for perovskite-related structure. Both the as-prepared compounds and the literature examples were proved to fit this correlation. This can be explained through the influence of the structural packing on the environment distortion and crystal field splitting of the doping site. - Graphical abstract: Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) show the dependence of luminescence properties on structural packing, among which Ca{sub 2}KNb{sub 5}O{sub 15} has the superior luminescence. Highlights: Black-Right-Pointing-Pointer Tungsten bronze compounds were synthesized by solid state reaction. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15} displayed remarkably blue host luminescence. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} showed more intense red emission than M{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} (M=Sr, Ba). Black-Right-Pointing-Pointer The relationship between crystal packing factor and luminescence was obtained.

Electrochemical fabrication of interconnected tungsten bronze nanosheets for high performance supercapacitor

Science.gov (United States)

Yang, Gan; Liu, Xiao-Xia

2018-04-01

Interconnected H0.12WO3ṡH2O nanosheets with high electrochemical performances are fabricated on partial exfoliated graphite substrate (Ex-GF) by potential-limited pulse galvanostatic method (PLPG). The dead volume problem of bulk pesudocapacitive materials is addressed by the novel interconnected nanosheets structure, enabling a large specific capacitance of 5.95 F cm-2 (495.8 F g-1) at 2 mA cm-2. Merited from the fluent electrolyte penetration channels established by the plenty voids among nanosheets, as well as fast electron transportation in the electronic conductive tungsten bronze which is directly grown from graphite substrate, the obtained WO3/Ex-GF demonstrates excellent rate capability. The material can maintain 60.0% of its capacitance when the discharge current density increases from 2 to 100 mA cm-2. Moreover, WO3/Ex-GF doesn't show capacitance decay after 5000 galvanostatic charge-discharge cycles, displaying its super stability. Furthermore, a high performance asymmetric supercapacitor assembled by using WO3/Ex-GF and electrochemical fabricated MnO2/Ex-GF as negative and positive electrodes, respectively displays a high energy density of 2.88 mWh cm-3 at the power density of 11.1 mW cm-3, demonstrating its potential application for energy storage.

Processing by both classical and mechanosynthesis routes and characterization of a new solid solution of tungsten-bronze structure ceramics

International Nuclear Information System (INIS)

Khachane, M.; Moure, A.; Elaatmani, M.; Zegzouti, A.; Daoud, M.; Castro, A.

2006-01-01

A new family of ferroelectric compounds with Ba 2-x Na 1+x Li x Nb 5 O 15 composition (0 ≤ x ≤ 1) and tetragonal tungsten-bronze structure is processed for the first time. This new family of materials derived from Ba 2 NaNb 5 O 15 compound was processed by classical solid-state reaction and by mechanosynthesis. The powders prepared by these two routes were characterized by X-ray diffraction (at room and high temperature), differential thermal analysis, thermogravimetry and scanning electron microscopy. The results confirm the formation of the solid solution in the whole range of composition. The influence of Li addition on the dielectric permittivity and losses and on the ferro-paraelectric transition temperature is also studied

Synthesis of new perovskite and ''tetragonal bronze'' materials with thorium

International Nuclear Information System (INIS)

Launay, Suzanne; Erb, Alfred; Freundlich, William

1982-01-01

Disclosure and crystal chemistry study of the solid solutions Th(NbO 3 ) 4 , NaNbO 3 or AgNbO 3 with perovskite structure and Th(Nb, TaO 3 ) 4 , K(Nb,Ta)O 3 with ''tetragonal tungstene bronze'' structure, ''Banana'' type [fr

Synthesis of new perovskite and ''tetragonal bronze'' materials with thorium

Energy Technology Data Exchange (ETDEWEB)

Launay, S; Erb, A; Freundlich, W [Universite Paris-VI (France)

1982-03-22

Disclosure and crystal chemistry study of the solid solutions Th(NbO/sub 3/)/sub 4/, NaNbO/sub 3/ or AgNbO/sub 3/ with perovskite structure and Th(Nb, TaO/sub 3/)/sub 4/, K(Nb,Ta)O/sub 3/ with ''tetragonal tungstene bronze'' structure, ''Banana'' type.

Evolution of coherent collective modes through consecutive charge-density-wave transitions in the (PO2)4(WO3)12 monophosphate tungsten bronze

Science.gov (United States)

Stojchevska, L.; Borovšak, M.; Foury-Leylekian, P.; Pouget, J.-P.; Mertelj, T.; Mihailovic, D.

2017-07-01

All-optical femtosecond relaxation dynamics in a single crystal of monophosphate tungsten bronze (PO2)4(WO3)2m with alternate stacking m =6 of WO3 layers was studied through the three consequent charge-density-wave (CDW) transitions. Several transient coherent collective modes associated with the different CDW transitions were observed and analyzed in the framework of the time-dependent Ginzburg-Landau theory. Remarkably, the interference of the modes leads to an apparent rectification effect in the transient reflectivity response. A saturation of the coherent-mode amplitudes with increasing pump fluence well below the CDWs destruction threshold fluence indicates a decoupling of the electronic and lattice parts of the order parameter on the femtosecond timescale.

Impact of copper substitution on the structural, ferroelectric and magnetic properties of tungsten bronze ceramics

Science.gov (United States)

Jindal, Shilpi; Devi, Sheela; Batoo, Khalid Mujasam; Kumar, Gagan; Vasishth, Ajay

2018-05-01

The copper substituted tungsten bronze ceramics with generic formula Ba5CaCuXTi2-xNb8O30(x = 0.0, 0.02, 0.04, 0.06 and 0.08) were successfully synthesized for the first time by solid state reaction method. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were utilized to examine the different structural parameters and elemental compositions. XRD study depicted the single phase tetragonal structure having space group P4bm. The crystallite size was observed to be in the range 14.4-30.23 nm. The coexistent of ferroelectricity and magnetism was established by P-E and M-H measurements. The P-E loop study indicated an increase in the coercive field (11.805-23.736 kVcm-1) while the M-H study depicted adecrease in the magnetization (7.65 × 10-4-5.32 × 10-4 emu/g) with the incorporation of Cu2+ ions. Raman spectrum depicted that there is shift in the position of Raman modes with the substitution of copper which revealed one-mode behavior in the synthesized ceramics.

Standard formation enthalpies of Nasub(2+x)Vsub(6)Osub(16-y) bronze of kappa type

International Nuclear Information System (INIS)

Khodos, M.Ya.; Slobodin, B.V.; Surat, L.L.; Fotiev, A.A.

1980-01-01

Standard formation enthalpies of sodium oxide vanadium bronze of kappa Nasub(2+x)Vsub(6)Osub(16-y) type of different composition have been determined by the method of solution calorimetry. It has been ascertained that within the limits of homogeneity a standard formation enthalpy decreases insignificantly with the increase of bronze oxygen defectiveness and is a linear function of sodium content

Electrical and optical properties of mixed phase tungsten trioxide films grown by laser pyrolysis

CSIR Research Space (South Africa)

Govender, M

2014-02-01

Full Text Available the tungstate bronzes to tungsten oxide. I-V curves of the films showed n-type semiconducting behaviour, but the mixed phase appeared to cause a similar behaviour of dopants in a semiconductor. The refractive index decreased with increasing wavelength and gave...

The effect of phosphorus on the formation of tungsten dioxide: A novel morphology

International Nuclear Information System (INIS)

Hegedus, E.; Neugebauer, J.

1999-01-01

The industrial production of tungsten is based on the hydrogen reduction of tungsten oxides, ammonium paratungstate (APT) or ammonium tungsten oxide bronze (ATOB). Hydrogen reduction is applied when high purity tungsten is required and when the addition of other elements or compounds (dopants) is desired for modification of the properties of the metal powder. The first stage of the reduction is finished when WO 2 is formed and it seems that the efficient incorporation of the additives starts mainly at this reduction step. The study reported here was undertaken to investigate the effect of phosphorus dope on the morphology of the intermediate tungsten dioxide and analyze its influence on the grain size of the final tungsten metal powder. The authors observed star shaped morphology of WO 2 , a structure which has not been describe in the literature. Contrary to the well-known cauliflower shaped tungsten dioxide, these starlets are not pseudomorphic to the initial ATOB particles; they grow separately and have a great influence on the grain size of the final metal powder

Phase II Tungsten Fate-and Transport Study for Camp Edwards

Science.gov (United States)

2010-02-01

cubic meters degrees Fahrenheit (oF-32)/1.8 degrees Celsius (oC) feet 0.3048 meters gallons (U.S. liquid) 3.785412 E-03 liters inches 0.0254 meters...1 Desorption/dissolution of tungsten 451 39 8.1 2 Sorption of sodium tungstate and desorption/dissolution of tungsten and sodium tungstate 124

Understanding metal–insulator transition in sodium tungsten bronze

Indian Academy of Sciences (India)

, A Chakraborty, D D Sarma, P Mahadevan, S. Oishi, W H McCarroll and M Greenblatt, Phys. Rev. B 75, 155116 (2007). [17] S Raj, A Chakraborty, D Choudhury, T Sato, T Takahashi, P Mahadevan, J Fujii, I Vobornik and D D Sarma, Phys. Rev.

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

International Nuclear Information System (INIS)

Dancsak, Stacia E.; Silva, Sidnei G.; Nóbrega, Joaquim A.; Jones, Bradley T.; Donati, George L.

2014-01-01

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

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

Effect of Annealing Time for Quenching CuAl7Fe5Ni5W2Si2 Bronze on the Microstructure and Mechanical Properties

Directory of Open Access Journals (Sweden)

B. P. Pisarek

2012-04-01

Full Text Available This paper presents the influence of annealing time 30, 60 and 120 min at 1000°C for quenching CuAl7Fe5Ni5W2Si2 bronze in 10% water solution of NaCl, on the microstructure and mechanical properties. The presented results concern the species newly developed aluminum-iron-nickel bronze, with additions W and Si.In order to determine changes in the microstructure of the hardened bronze metallographic studies were performed on cylindrical samples of diameter 10 mm, on the metallographic microscope with digital image analysis, X-ray phase analysis, EDX point with the digital recording on the computer. Specified percentage of the microstructure of martensite and bainite, participation of proeutectoid α phase in the microstructure, grain size of former β phase, the amount of dissolved κ phase.It was found that in the microstructure of bronze in the cast state, there are a number of intermetallic phases of κ type. At interphase boundaries of primary intermetallic faceted precipitates, especially rich in tungsten (IM_W, nucleate and grow dendritic primary intermetallic κI phases, with chemical composition similar to the type of Fe3Si iron silicide.Dissolved, during the heating, in the β phase are all the intermediate phase included in the microstructure, with the exception of primary intermetallic phases of tungsten and κI. Prolongation of the isothermal annealing causes coagulation and coalescence of primary phases. In microstructure of the bronze after quenching obtained the α phase precipitation on the grain boundary of secondary β phase, coarse bainite and martensite, for all annealing times. With the change of annealing time are changed the relative proportions of individual phases or their systems, in the microstructure. In the microstructure of bronze, hold at temperature of 1000°C for 60 min, after quenching martensitic microstructure was obtained with the primary phases, and the least amount of bainite.

Corrosion of high-density sintered tungsten alloys

International Nuclear Information System (INIS)

Batten, J.J.; Moore, B.T.

1989-01-01

In comparative corrosion tests, the corrosion resistance of an Australian tungsten alloy (95% W, 3.5% Ni, 1.5% Fe) was found to be superior to three other tungsten alloys and, under certain conditions, even more corrosion-resistant than pure tungsten. Corrosion resistance was evaluated after immersion in both distilled water and 5% sodium chloride solutions, and in cyclic humidity and salt mist environments. For all but the Australian alloy, the rate of corrosion in sodium chloride solution was markedly less than that in distilated water. In all cases, alloys containing copper had the greatest corrosion rates. Corrosion mechanisms were investigated using a scanning electron microscope, analysis of corrosion products and galvanic corrosion studies. For the alloys, corrosion was attributed primarily to a galvanic reaction. Whether the tungsten or binder phase of the alloy became anodic, and thus was attacked preferentially, depended upon alloy composition and corrosion environment. 16 refs., 4 tabs., 4 figs

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

International Nuclear Information System (INIS)

Gagou, Y.; Lukyanchuk, I.; El Marssi, M.; Amira, Y.; Mezzane, D.; Courty, M.; Masquelier, C.; Yuzyuk, Yu. I.

2014-01-01

Phase transitions in gadolinium potassium niobate GdK 2 Nb 5 O 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 c1  = 238 °C and T 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 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

Upper limit for magnetoresistance in silicon bronze and phosphor bronze wire

Science.gov (United States)

Feldman, R.; Talley, L.; Rojeski, M.; Vold, T.; Woollam, J. A.

1977-01-01

The electrical resistivity of silicon bronze and phosphor bronze was measured in magnetic fields from 0 to 14 T and at temperatures between 2 and 300 K. At any fixed temperature, the change in resistivity to 14 T was less than a few parts in 100,000. Thus, these bronzes are excellent for use in high magnetic fields where constant resistance is required. Welding leads to the sample was found to be superior to soldering. The soldered contacts were subject to spurious resistivity changes that resulted from superconducting transitions in the solder.

Study of the tungsten bronze Ag0.01WO3 using positron annihilation method

International Nuclear Information System (INIS)

Dryzek, J.; Dryzek, E.; Placzek, A.

1992-01-01

The study of the positron annihilation and the Seebeck effect was performed on silver doped tungsten trioxide of composition Ag 0.01 WO 3 and the tungsten trioxide phase: WO 2.90 (W 20 O 58 ). Both methods point out that there are some clusters of Ag + ions in the first compound and oxygen vacancies in the second case. The clusters have some internal substructure. The measurements of the Seebeck effect showed that Ag 0.01 WO 3 is normal n-type semiconductor whereas WO 2.90 exhibits metal-like properties

75 FR 14257 - Pricing for Bronze Medals

Science.gov (United States)

2010-03-24

... 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 bronze medals, 1\\1/2\\-inch bronze medals and three-inch bronze medals. Beginning March...

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.

Nonstoichiometric control of tunnel-filling order, thermal expansion, and dielectric relaxation in tetragonal tungsten Bronzes Ba0.5-xTaO3-x.

Science.gov (United States)

Pan, Fengjuan; Li, Xiaohui; Lu, Fengqi; Wang, Xiaoming; Cao, Jiang; Kuang, Xiaojun; Véron, Emmanuel; Porcher, Florence; Suchomel, Matthew R; Wang, Jing; Allix, Mathieu

2015-09-21

Ordering of interpolated Ba(2+) chains and alternate Ta-O rows (TaO)(3+) in the pentagonal tunnels of tetragonal tungsten bronzes (TTB) is controlled by the nonstoichiometry in the highly nonstoichiometric Ba0.5-xTaO3-x system. In Ba0.22TaO2.72, the filling of Ba(2+) and (TaO)(3+) groups is partially ordered along the ab-plane of the simple TTB structure, resulting in a √2-type TTB superstructure (Pbmm), while in Ba0.175TaO2.675, the pentagonal tunnel filling is completely ordered along the b-axis of the simple TTB structure, leading to a triple TTB superstructure (P21212). Both superstructures show completely empty square tunnels favoring Ba(2+) conduction and feature unusual accommodation of Ta(5+) cations in the small triangular tunnels. In contrast with stoichiometric Ba6GaTa9O30, which shows linear thermal expansion of the cell parameters and monotonic decrease of permittivity with temperature within 100-800 K, these TTB superstructures and slightly nonstoichiometric simple TTB Ba0.4TaO2.9 display abnormally broad and frequency-dependent extrinsic dielectric relaxations in 10(3)-10(5) Hz above room temperature, a linear deviation of the c-axis thermal expansion around 600 K, and high dielectric permittivity ∼60-95 at 1 MHz at room temperature.

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.

Corrosion of high-density sintered tungsten alloys. Part 1

International Nuclear Information System (INIS)

Batten, J.J.; McDonald, I.G.; Moore, B.T.; Silva, V.M.

1988-10-01

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

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.

The determination of iron, chromium, titanium, and tungsten by x-ray-fluorescence spectrometry

International Nuclear Information System (INIS)

Austen, C.E.

1977-01-01

An accurate and precise method is described for the determination of iron and chromium in chromite, iron and titanium in ilmenite, and tungsten in tungsten ores. Samples are prepared for analysis by fusion with sodium peroxide or sodium tetraborate and leaching of the melt in a solution of tartaric or hydrochloric acid. Matrix correction and calibration are achieved by means of the single-standard calibration method with reference solutions prepared from compounds of the elements determined

Novel sodium intercalated (NH4)2V6O16 platelets: High performance cathode materials for lithium-ion battery.

Science.gov (United States)

Fei, Hailong; Wu, Xiaomin; Li, Huan; Wei, Mingdeng

2014-02-01

A simple and versatile method for preparation of novel sodium intercalated (NH4)2V6O16 is developed via a simple hydrothermal route. It is found that ammonium sodium vanadium bronze displays higher discharge capacity and better rate cyclic stability than ammonium vanadium bronze as lithium-ion battery cathode material because of smaller charge transfer resistance, which would favor superior discharge capacity and rate performance. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

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...... 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...

Positron lifetime in vanadium oxide bronzes

International Nuclear Information System (INIS)

Dryzek, J.; Dryzek, E.

2003-01-01

The positron lifetime (PL) and Doppler broadening (DB) of annihilation line measurements have been performed in vanadium oxide bronzes M x V 2 O 5 . The dependence of these annihilation characteristics on the kind and concentration of the metal M donor has been observed. In the PL spectrum only one lifetime component has been detected in all studied bronzes. The results indicate the positron localization in the structural tunnels present in the crystalline lattice of the vanadium oxide bronzes. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Sliding charge density wave in the monophosphate tungsten bronze (PO2)4(WO3)2m with alternate stacking of m=4 and m=6 WO3 layers

International Nuclear Information System (INIS)

Foury-Leylekian, P.; Sandre, E.; Ravy, S.; Pouget, J.-P.; Elkaim, E.; Roussel, P.; Groult, D.; Labbe, Ph.

2002-01-01

The monophosphate tungsten bronzes (PO 2 ) 4 (WO 3 ) 2m form family of two-dimensional metals which exhibit charge density wave (CDW) instabilities. These materials are generally built by the regular stacking of (a,b) layers in which chains made of segments of m WO 6 octahedra directed along the a and a±b directions are delimited. Their electronic structure thus originates from quasi-one-dimensional (1D) bands located on these chains. As a consequence their Fermi surface (FS) exhibits large flat portions whose nesting gives rise to successive CDW instabilities. Here we present a structural study of the CDW instability of the (PO 2 ) 4 (WO 3 ) 10 member formed by the alternate stacking of layers built with segments of m=4 and m=6 WO 6 octahedra. Its ab initio electronic structure calculation shows that the FS of this member exhibits large flat portions which can be extremely well nested. Its best nesting wave vector accounts for the modulation wave vector stabilized by the CDW transition which occurs at 156 K. Because of the regular stacking of layers of different m values the FS is slightly split. The unusual thermal dependence of the x-ray satellite intensity provides evidence that the two types of layers become modulated at different temperature. This also leads to a slight thermal sliding of the CDW-nesting modulation wave vector, which can be accounted for within the framework of a Landau-Ginzburg theory. In addition, the observation of a global hysteresis in the thermal cycling of the satellite intensity, as well as the degradation of the interlayer order upon cooling, suggest the formation of a disordered lattice of dilute solitons. Such solitons allow to accommodate the charge transferred between the two types of layer. Finally the relevance of local charge transfers, at intergrowth defects, for example, to create pinned discommensurations that break the CDW coherence is emphasized in this whole family of bronzes

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...

Thermochemical investigation of lithium-vanadium bronzes

International Nuclear Information System (INIS)

Filippova, S.E.; Kesler, Ya.A.; Tret'yakov, Yu.D.; Gordeev, I.V.

1979-01-01

A thermochemical investigation was carried out of lithium-vanadium bronzes. The enthalpies of solution and the standard enthalpies of formation of the bronzes β-Lisub(x)Vsub(2)Osub(5) were determined. Investigated was the dependence of the enthalpy of mixing bronzes on the composition; a linear character of the dependence evidences of negligibly small, as compared to the experimental error, energy variations of the matrix V 2 O 5 on introduction of lithium. The variation was calculated of the partial molar enthalpy of lithium in the formation of β-Lisub(x)Vsub(2)Osub(5)

Granulation of Cu-Al-Fe-Ni Bronze

Directory of Open Access Journals (Sweden)

Pisarek B.P.

2014-08-01

Full Text Available With the increase in wall thickness of the casting of iron-nickel-aluminium-bronze, by the reduction of the cooling rate the size of κII phase precipitates increases. This process, in the case of complex aluminium bronzes with additions of Cr, Mo and W is increased. Crystallization of big κII phase, during slow cooling of the casting, reduces the concentration of additives introduced to the bronze matrix and hardness. Undertaken research to develop technology of thick-walled products (g> 6 mm of complex aluminium bronzes. Particular attention was paid to the metallurgy of granules. As a result, a large cooling speed of the alloy, and also high-speed solidification casting a light weight of the granules allows: to avoid micro-and macrosegregation, decreasing the particle size, increase the dispersion of phases in multiphase alloys. Depending on the size granules as possible is to provide finished products with a wall thickness greater than 6 mm by infiltration of liquid alloy of granules (composites. Preliminary studies was conducted using drip method granulate of CuAl10Fe5Ni5 bronze melted in a INDUTHERM-VC 500 D Vacuum Pressure Casting Machine. This bronze is a starting alloy for the preparation of the complex aluminium bronzes with additions of Cr, Mo, W and C or Si. Optimizations of granulation process was carried out. As the process control parameters taken a casting temperature t (°C and the path h (mm of free-fall of the metal droplets in the surrounding atmosphere before it is intensively cooled in a container of water. The granulate was subjected to a sieve analysis. For the objective function was assume maximize of the product of Um*n, the percentage weight “Um” and the quantity of granules ‘n’ in the mesh fraction. The maximum value of the ratio obtained for mesh fraction a sieve with a mesh aperture of 6.3 mm. In the intensively cooled granule of bronze was identified microstructure composed of phases: β and fine bainite

Hydrothermal synthesis of electrode materials pyrochlore tungsten trioxide film

Science.gov (United States)

Guo, Jingdong; Li, Yingjeng James; Stanley Whittingham, M.

Hydrothermal synthesis methods have been successfully used to prepare new transition-metal oxides for cathodes in electrochemical devices such as lithium batteries and electrochromic windows. The tungsten oxides were the first studied, but the method has been extended to the oxides of molybdenum, vanadium and manganese. Sodium tungsten oxide films with the pyrochlore structure have been prepared on gold/alumina and indium-doped tin oxide substrates. These films reversibly and rapidly intercalate lithium and hydrogen ions.

Chromaticity and Glossiness of Gold, Silver, and Bronze Colors

Directory of Open Access Journals (Sweden)

Tomohisa Matsumoto

2011-05-01

Full Text Available Appearance of metallic colors, such as gold, silver and bronze, depends on chromaticity and glossiness of a surface. We aim to obtain the chromaticity region of gold, silver, and bronze by using CG simulated surfaces with various glossiness. The physical glossiness was defined by the intensity ratio of specular reflectance of the surface stimulus. The observer estimated degree of perceived glossiness, and also degree of gold, silver, or bronze appearance of the stimulus with a physical glossiness and a chromaticity. The results showed that the stimulus began to appear gold, silver or bronze at a certain chromaticity point only when the stimulus had glossiness. The chromaticity range, where gold, silver and bronze colors were observed, expanded as the degree of glossiness increased. Furthermore the ratio of the degree of gold, silver or bronze colors to that of glossiness of the stimulus was found to be different among the chromaticity points of the stimulus. This ratio was highest with highly saturated stimuli for gold and bronze colors, and with achromatic stimuli for silver color.

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.

A lead isotope ratio data base of ancient Chinese bronzes

International Nuclear Information System (INIS)

Jin Zhengyao

2005-01-01

A data base of lead isotope ratio of ancient Chinese bronzes is set up. There are 2888 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. (author)

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....

Corrosion evaluation of traditional and new bronzes for artistic castings

International Nuclear Information System (INIS)

Chiavari, C.; Colledan, A.; Frignani, A.; Brunoro, G.

2006-01-01

By electrochemical and accelerated weathering tests, the corrosion behaviour of a new type of tin-bronze, containing about 3 wt.% silicon (SI3 bronze) was compared to a traditional 5% Sn, 5% Zn, 5% Pb bronze used for artistic castings (G85 bronze) under conditions simulating urban-industrial and marine environments. The aggressive media were: a synthetic pH 3.1 acid rain (AR) solution; a typical moist SO 2 -NO x for a climatic chamber and AR or 3.5% NaCl aqueous solution for salt spray cabinet. In all the environments the corrosion product layers formed on SI3 bronze were more uniform and protective than those formed on the traditional G85 bronze. The nature and morphology of the corrosion products were investigated by X-ray diffraction (XRD), optical and scanning electron microscopy with microprobe (SEM-EDS), atomic force microscopy (AFM)

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.

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; Mak, C. L.; Ploss, Bernd

2012-01-01

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.

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

... DEPARTMENT OF THE TREASURY United States Mint Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse Bronze Medal Set and the Birth Set AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing 2012 pricing for...

Titrimetric determination of tungsten in its alloys with tantalum

International Nuclear Information System (INIS)

Elinson, S.V.; Nezhnova, T.I.

1982-01-01

Titrimetric method of tungsten determination in tantalum base alloys has been developed. The method permits to determine 5-10% tungsten in the alloys with relative standard deviation of 0.013. The conditions are created by application of precipitation from homogeieous solutions or by the method of appearing reagents at pH values, which condition gradual hydrolytic precipitation of tantalum, and sodium tungstate remains in the solution and is not sorbed on tantalum hydroxide. After separation of tantalum oxide tungsten is precipitated in the form of lead tungstate by the excess of ti trated solution of lead salt during boiling and then at the background of lead tungstate precipitate without its separation lead excess is titrated by EDTA in the presence of mixed indicator-4-(2-pyridylazo)resocinol and xylenole orange in acetate buffer solution

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.

Effect of tempering on corrosion resistance of cast aluminium bronzes

International Nuclear Information System (INIS)

Aaltonen, P.; Klemetti, K.; Haenninen, H.

1985-01-01

The subject of this study is corrosion resistance of aluminium bronzes, which are copper base alloys containing aluminium up to 12% with additions of nickel, iron and manganese. The main conclutions that can be drawn are: (1) The dealloying corrosion resistance of nickel-aluminium bronze is much better than that of aluminium bronze with iron and manganese additions, but it is not immune; (2) The dealloying corrosion resistance of aluminium bronzes can be improved by appropiate heat treatments. The best properties were obtained by temperering between 600 and 800 deg C, depending on the initial microstructure; (3) In crevice conditions, where local acidification can occur, dealloying of aluminium bronzes is a consequence of the preferential attack of aluminium-rich phases. By appropriate tempering, a uniform distribution of aluminium-rich phases is obtained and the continous path for selective corrosion is not formed

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

2016-03-18

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.

Determination of tungsten and tin ions after preconcentration by flotation

International Nuclear Information System (INIS)

Dietze, U.; Kunze, S.

1990-01-01

A highly sensitive and selective combined method of flotation followed by spectrophotometry/d.c. polarography for the determination of tungsten and tin ions in acid and alkaline waste waters and hydrometallurgical solutions is presented here. Both kinds of ions are coprecipitated in the analyte solution with zirconium hydroxide after addition of ZrOCl 2 solution and ammonia. Afterwards, the collector precipitate is separated from the aqueous phase and preconcentrated by flotation for which sodium oleate and a frother are added. The precipitate is dissolved in a small amount of acid, with the organic reagents being destroyed by oxidation. The enrichment factor of the proposed technique is 100, with variations possible. Recovery is 94 % for tungsten and 99 % for tin. Spectrophotometry of the thiocyanate complex and d.c. polarography are applied as determination techniques for tungsten and tin, respectively. Detection limits attainable by this technique are 6 ng.ml -1 for tungsten and 5 ng.ml -1 for tin for the initial sample. (Authors)

Setup of Galvanic Sensors for the Monitoring of Gilded Bronzes

Directory of Open Access Journals (Sweden)

Sara Goidanich

2014-04-01

Full Text Available Traditional electrochemical techniques, such as linear polarization resistance (Rp, and electrochemical impedance spectroscopy (EIS, cannot be applied to gilded bronzes, as it may not be possible to interpret the results obtained due to the bimetallic nature of the studied material. The measurement of the macrocouple current generated by the gold/bronze galvanic couple can be used as an indicator of degradation processes. Nevertheless, this measurement cannot be performed directly on the original artifacts due to the systematic presence of short-circuits between the two metals. In the present work the use of galvanic sensors is proposed as a possible solution for the monitoring of gilded bronze artefacts. The sensors have been designed to simulate real gilded bronze surfaces in terms of composition and stratigraphy and have proved to be a reliable diagnostic tool for the in situ monitoring of the rates of deterioration of gilded bronze surfaces and to test new conservation treatments. Their set-up and application is reported and their performances discussed.

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.

Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

International Nuclear Information System (INIS)

Patil, V.B.; Adhyapak, P.V.; Suryavanshi, S.S.; Mulla, I.S.

2014-01-01

Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO 3 was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO 3 , however, on addition of oxalic acid a single phase hexagonal WO 3 with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO 3 bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm −1 ) for 72 h of heating at 170 °C

Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

Energy Technology Data Exchange (ETDEWEB)

Patil, V.B. [School of Physical Sciences, Solapur University, Solapur 413255 (India); Adhyapak, P.V. [Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University, Solapur 413255 (India); Mulla, I.S., E-mail: ismulla2001@gmail.com [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India)

2014-03-25

Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO{sub 3} was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO{sub 3}, however, on addition of oxalic acid a single phase hexagonal WO{sub 3} with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO{sub 3} bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm{sup −1}) for 72 h of heating at 170 °C.

Development and electrochemical characterization of Ni‐P coated tungsten incorporated electroless nickel coatings

Energy Technology Data Exchange (ETDEWEB)

Shibli, S.M.A., E-mail: smashibli@yahoo.com; Chinchu, K.S.

2016-08-01

Ni‐P-W alloy and composite coatings were prepared by incorporation of sodium tungstate/tungsten and Ni‐P coated tungsten into electroless nickel bath respectively. Good inter-particle interactions among the depositing elements i.e. Ni and P with the incorporating tungsten particles were achieved by means of pre-coated tungsten particle by electroless nickel covering prior to its addition into the electroless bath. The pre-coated tungsten particles got incorporated uniformly into the Ni-P matrix of the coating. The particles and the coatings were characterized at different stages by different techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The electroless Ni-P coating incorporated with pre-coated tungsten exhibited considerably high hardness, thickness and deposition rate. The performance and corrosion resistance characteristics of the composite coating incorporated with the nickel coated tungsten were found to be superior over other conventional Ni-P-W ternary alloy coatings currently reported. - Highlights: • An amorphous Ni-P coating was effectively formed on tungsten particles. • Electroless ternary Ni-P-W composite coatings were successfully prepared. • Enhancement in the inter-particle interaction in the Ni-P composite matrix was achieved. • Efficient and uniform incorporation of the composite in the internal layer was evident. • The tungsten incorporated coating possessed effective barrier protection.

Manufacturing method of the bronze metallic filters

International Nuclear Information System (INIS)

Krivij, N.; Suwardjo, W.; Garcia, L.; Cores, A.; Formoso, A.

1997-01-01

Granulated (spherical) powders of bronze have been produced by spraying molten metal with gas at high pressure in the experimental industrial installation belonging to the Metallurgical Research Centre (CIME) in Havana City. A physical-chemical and technological characterisation of the spherical bronze powder has been carried out and the optimum parameters have been determined from these powders. The mechanical properties of these filters can satisfactorily rival in applications such as in motor transport goods, in industry and agriculture. (AUthor)

Metallography and microstructure interpretation of some archaeological tin bronze vessels from Iran

Energy Technology Data Exchange (ETDEWEB)

Oudbashi, Omid, E-mail: o.oudbashi@aui.ac.ir [Department of Conservation of Historic Properties, Faculty of Conservation, Art University of Isfahan, Hakim Nezami Street, Sangtarashha Alley, P.O. Box 1744, Isfahan (Iran, Islamic Republic of); Davami, Parviz, E-mail: pdavami@razi-foundation.com [Faculty of Material Science and Engineering, Sharif University of Technology/Razi Applied Science Foundation, No. 27, Fernan St., Shahid Ghasem Asghari Blvd., km 21 of Karadj Makhsous Road, Tehran (Iran, Islamic Republic of)

2014-11-15

Archaeological excavations in western Iran have recently revealed a significant Luristan Bronzes collection from Sangtarashan archaeological site. The site and its bronze collection are dated to Iron Age II/III of western Iran (10th–7th century BC) according to archaeological research. Alloy composition, microstructure and manufacturing technique of some sheet metal vessels are determined to reveal metallurgical processes in western Iran in the first millennium BC. Experimental analyses were carried out using Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy and Optical Microscopy/Metallography methods. The results allowed reconstructing the manufacturing process of bronze vessels in Luristan. It proved that the samples have been manufactured with a binary copper–tin alloy with a variable tin content that may relates to the application of an uncontrolled procedure to make bronze alloy (e.g. co-smelting or cementation). The presence of elongated copper sulphide inclusions showed probable use of copper sulphide ores for metal production and smelting. Based on metallographic studies, a cycle of cold working and annealing was used to shape the bronze vessels. - Highlights: • Sangtarashan vessels are made by variable Cu-Sn alloys with some impurities. • Various compositions occurred due to applying uncontrolled smelting methods. • The microstructure represents thermo-mechanical process to shape bronze vessels. • In one case, the annealing didn’t remove the eutectoid remaining from casting. • The characteristics of the bronzes are similar to other Iron Age Luristan Bronzes.

Tungsten oxide thin film exposed to low energy D and He plasma: evidence for a thermal enhancement of the erosion yield

Science.gov (United States)

Hijazi, Hussein; Martin, C.; Roubin, P.; Addab, Y.; Cabie, C.; Pardanaud, C.; Bannister, M.; Meyer, F.

2017-10-01

Nanocrystalline tungsten oxide thin films (25 nm - 250 nm thickness) produced by thermal oxidation of a tungsten substrate were exposed to low energy D and He plasma. Low energy D plasma exposure (11 eV/D+) of these films have resulted in the formation of a tungsten bronze (DxWO3) clearly observed by Raman microscopy. D plasma bombardment (4 1021 m-2) has also induced a color change of the oxide layer which is similar to the well-known electro-chromic effect and has been named ``plasma-chromic effect''. To unravel physical and chemical origins of the modifications observed under exposure, similar tungsten oxide films were also exposed to low energy helium plasma (20 eV/He+) . Due to the low fluence (4 1021 m-2) and low ion energy (20 eV), at room temperature, He exposure has induced only very few morphological and structural modifications. On the contrary, at 673 K, significant erosion is observed, which gives evidence for an unexpected thermal enhancement of the erosion yield. We present here new results concerning He beam exposures at low fluence (4 1021 m-2) varying the He+ energy from 20 eV to 320 eV to measure the tungsten oxide sputtering threshold energy. Detailed analyses before/after exposure to describe the D and He interaction with the oxide layer, its erosion and structural modification at the atomic and micrometer scale will be presented.

Tungsten

International Nuclear Information System (INIS)

Eschnauer, H.

1978-01-01

There is no substitute for tungsten in its main field of application so that the demand will not decrease, but there is a need for further important applications. If small variations are left out of account, a small but steady increase in the annual tungsten consumption can be expected. The amount of tungsten available will increase due to the exploritation of new deposits and the extension of existing mines. This tendency will probably be increased by the world-wide prospection. It is hard to make an assessment of the amount of tungsten are obtained in the People's Republic of china, the purchases of Eastern countries in the West, and the sales policy of the USA; pice forecasts are therefore hard to make. A rather interesting subject with regard to the tungsten cycle as a whole is the reprocessing of tungsten-containing wastes. (orig.) [de

Synchrotron X-ray diffraction and imaging of ancient Chinese bronzes

International Nuclear Information System (INIS)

Young, M.L.; Dunand, D.C.; Casadio, F.; Schnepp, S.; Almer, J.; Haeffner, D.R.

2006-01-01

High-energy synchrotron X-ray diffraction and imaging experiments were performed at the Advanced Photon Source on two ancient Chinese bronzes from the Art Institute of Chicago with the goal to nondestructively study their microstructure. The first object, a bronze fragment from an early Western Zhou dynasty vessel (Hu, 11th/10th century B.C.), was investigated with spatially-resolved diffraction to reveal the depth and composition of the surface corrosion layer as well as the composition and grain size of the underlying bronze core. The second object, a bronze dagger-axe (Ge, 3rd/2nd century B.C.) with a silver-inlaid sheath, was studied under both diffraction and imaging conditions. It was found to have been cast as a single object, answering longstanding scholars' questions on whether the ceremonial object concealed an interior blade. (orig.)

Copper smelting and sediment pollution in Bronze Age China.

Science.gov (United States)

Zhang, S.; Dong, G.

2017-12-01

The emergence and diffusion of metallurgical technology had tremendous environmental consequence, however, the spatial-temporal consequences of the metallurgy during Bronze Age are not clear in China. Here, Xray fluorescence (XRF) measurement and principal component analysis (PCA) were conducted on heavy metal element (Cu, Ni, Pb, Zn, Cr and As) concentrations (HMEC) of natural and anthropogenic sediment samples systematically collected from 22 late Neolithic-Bronze Age sites in Hexi corridor to explore the potential for subcontinental-wide changes in soil geochemistry. We place this data within the context of the Cu concentrations in lacustrine sediments located near smelting and mining centers in Bronze Age China. Our results show that variation of HMEC in anthropogenic sediment in Hexi corridor is contemporaneous with the increases of the Cu concentrations in lacustrine sediment around 4000 BP. Comparative data suggests the metallurgical production diffused from the Hexi corridor to central and southwestern China around 3600 BP. We argue that sediment pollution is not an isolated phenomenon during the Bronze Age China, but rather occurred on regional scales and is closely related to the intensity of smelting activities.

Combined aging of beryllium bronze

International Nuclear Information System (INIS)

Duraev, P.P.; Kaplun, Yu.A.; Pastukhova, Zh.P.; Rakhshtadt, A.G.

1986-01-01

This article evaluates the possibility of increasing the resistance of beryllium bronze to small plastic deformations as a result of the application of stepped aging under stress. Low-temperature aging under conditions of bending under a stress of about 100 MPa was applied to alloy BrBNT1, 9Mg at 150, 180, and 210 0 C, high-temperature aging at 300 and 340 0 C under stress and without stress. As a result of applying stepped aging under stress, the elastic limit of the alloy BrBNT1, 9Mg was raised to 900 MPa. Stepped aging under stress has a substantial effect on the relaxation stability of the alloy. The procedure suggested in the article for aging may be used efficiently for treating elastic elements made of other brands of bronze as well

Prompt gamma-ray analysis of archaeological bronze

International Nuclear Information System (INIS)

Oura, Y.; Saito, A.; Sueki, K.; Nakahara, H.; Tomizawa, T.; Nishikawa, T.; Yonezawa, C.; Matsue, H.; Sawahata, H.

1999-01-01

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)

The Early-Middle bronze ages tombs from the Kartal fortress

Directory of Open Access Journals (Sweden)

Igor Bruiako

2017-09-01

Full Text Available The burials of Early- and Middle Bronze Age discovered by excavations of Kartal hill fort are analyzed in this article. One part of them belongs to the Pit-Grave Culture (later period, another – to the Culture Mnogovalikovaja. Allburials aresituated in the vicinity of ancient site, abandoned during the most part of the Bronze Age. The part of Pit-Grave burials representsflat/ pitgraves (non-kurgan. We assume that the seasonal settlement was located here in some periods of Bronze Age, while in the steppe of Eastern Europe dominated the populations of cattle-breeders.

An important harvest by applying Pb-isotope analysis to ancient Chinese bronzes

International Nuclear Information System (INIS)

Jin Zhengyao

2003-01-01

Analysing numerous ancient Chinese bronze objects unearthed at the archaeological sites by lead isotopic method, we found that a major portion Shang (1600 B. C.-1100 B. C.) bronzes contained a kind of high-radiogenic lead, The results suggested that there is a 'bronze road' linking the Shang sites in both of the Yellow River valley and the Yangtze River valley in Shang dynasty. (authors)

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

Evaluation of some phenothiazine derivatives as corrosion inhibitors for bronze in weakly acidic solution

International Nuclear Information System (INIS)

Bostan, Roxana; Varvara, Simona; Găină, Luiza; Mureşan, Liana Maria

2012-01-01

Highlights: ► Phenothiazine derivatives are efficient inhibitors for bronze corrosion. ► Potentiodynamic polarization and EIS were used to elucidate inhibition mechanism. ► Adsorption of phenothiazine derivatives on bronze surface obeys Langmuir isotherm. ► A correlation between energy gaps and inhibition efficiencies values was obtained. - Abstract: Four phenothiazine derivatives have been tested as inhibitors for bronze corrosion in a solution containing Na 2 SO 4 and NaHCO 3 (pH 5). Electrochemical investigations (potentiodynamic polarisation and impedance measurements) revealed that all phenothiazine derivatives exert a protective effect against bronze corrosion and, in some cases their inhibition efficiency exceeds 90% at concentration level as low as 75 μM. An adherent layer of organic molecules chemisorbed on bronze surface is responsible for the protective effect of the investigated compounds. Adsorption of phenothiazine derivatives on bronze obeys Langmuir isotherm. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compounds was discussed using DFT method.

Separation of tungsten and rhenium on alumina

Directory of Open Access Journals (Sweden)

MILOVAN SM. STOILJKOVIC

2004-09-01

Full Text Available The conditions for the efficient separation of tungsten(VI and rhenium (VII on alumina were established. The distribution coefficients Kd for tungstate and perrhenate anions, as well as the separation factors a (a = KdWO42-/Kd ReO4- were determined using hydrochloric or nitric acid as the aqueous media. A solution of sodium chloride in the pH range 2–6 was also examined. Under all the tested experimental conditions, alumina is a much better adsorbent for tungsten than for rhenium. The obtained results indicated that the best separation of these two elements is achieved when 0.01– 0.1 mol dm-3 HCl or 1.0 mol dm-3 HNO3 are used as the aqueous media. If NaCl is used as the aqueous phase, the best separation is achieved with 0.20 mol dm-3 NaCl, pH 4–6. Under these experimental conditions, the breakthrough and saturation capacities of alumina for tungsten at pH 4 are 17 and 26 mg W/g Al2O3, respectively. With increasing pH, these values decrease. Thus, at pH 6 they are only 4 and 13 mg W/g Al2O3, respectively.

Characterisation of a Proto-historic bronze collection by micro-EDXRF

International Nuclear Information System (INIS)

Figueiredo, Elin; Araújo, M. Fátima; Silva, Rui J.C.; Vilaça, Raquel

2013-01-01

Highlights: ► A collection of Proto-historic metal artefacts was analysed by micro-EDXRF. ► Composition of major and minor elements has been determined. ► Artefacts were manufactured in a bronze alloy with a low impurity pattern. ► The alloy shows parallels with indigenous Late Bronze Age Iberian productions. -- Abstract: Studies concerning European Proto-historic metallic artefacts can provide important clues about technological transfers during a period of time characterised by diverse cultural interactions. A collection of Proto-historic metallic artefacts from Medronhal (western Iberian Peninsula) composed by rings, bracelets and a fibula related to different cultural affiliations were investigated by micro-EDXRF to provide a major and a minor elemental characterisation. Results show that the Medronhal collection was manufactured in a Cu–Sn alloy (binary bronze) with similar Sn contents among the various types of artefacts and a low impurity pattern. Results of the type and quality of metal were compared to other artefact collections to infer about metallurgical parallels. Strong parallels with indigenous Late Bronze Age Iberian metallurgical productions were found

Characterisation of a Proto-historic bronze collection by micro-EDXRF

Energy Technology Data Exchange (ETDEWEB)

Figueiredo, Elin, E-mail: elin@itn.pt [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Araújo, M. Fátima [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Silva, Rui J.C. [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Vilaça, Raquel [CEAUCP-FCT, Instituto de Arqueologia, Departamento de História, Arqueologia e Artes, Faculdade de Letras, Universidade de Coimbra, Palácio de Sub-Ripas, 3000-395 Coimbra (Portugal)

2013-02-01

Highlights: ► A collection of Proto-historic metal artefacts was analysed by micro-EDXRF. ► Composition of major and minor elements has been determined. ► Artefacts were manufactured in a bronze alloy with a low impurity pattern. ► The alloy shows parallels with indigenous Late Bronze Age Iberian productions. -- Abstract: Studies concerning European Proto-historic metallic artefacts can provide important clues about technological transfers during a period of time characterised by diverse cultural interactions. A collection of Proto-historic metallic artefacts from Medronhal (western Iberian Peninsula) composed by rings, bracelets and a fibula related to different cultural affiliations were investigated by micro-EDXRF to provide a major and a minor elemental characterisation. Results show that the Medronhal collection was manufactured in a Cu–Sn alloy (binary bronze) with similar Sn contents among the various types of artefacts and a low impurity pattern. Results of the type and quality of metal were compared to other artefact collections to infer about metallurgical parallels. Strong parallels with indigenous Late Bronze Age Iberian metallurgical productions were found.

Non-destructive analysis of archaeological bronzes by nuclear techniques

International Nuclear Information System (INIS)

Respaldiza, M.A.; Gomez-Tubio, B.M.; Sanchez del Junco, A.; Barranco, F.; Saiz-Jimenez, C.

1994-01-01

This paper studies a method for overcoming the difficulty of corroded surfaces by means of nondestructive nuclear methods in the determination of the composition of archaeological bronzes. It consists of the combination of PIXE or XRF information with Gamma Ray Transmission (GRT) data. A wide range applicability of this combined method is established by comparison with profiles of concentrations along the bronzes' patina obtained by SEM-EDAX. (orig.)

Tungsten and tungsten alloys by powder metallurgy

International Nuclear Information System (INIS)

Belhadjhamida, A.; German, R.M.

1991-01-01

Tungsten has a historical link with powder metallurgy and there is continued progress in expanding the available compositions and processing options. This paper starts with an introduction to the history of tungsten powder metallurgy and use this as a basis for analyzing some of the current trends. The literature base in tungsten processing is expanding and includes new alloys, microstructures, and processing routes. A few examples will be emphasize here to produce a frame work for this program, including description of sintering mechanisms for tungsten, liquid phase sintering advances, hot consolidation fundamentals, and options for complex shaping using powder injection modeling. For this base, subsequent presentations will expand on these fundamental advances

Application of SIMS in patina studies on Bronze Age copper alloys

International Nuclear Information System (INIS)

Wouters, H.J.; Butaye, L.A.; Adams, F.C.

1992-01-01

The potential of secondary ion mass spectrometry for the patina studies on Bronze Age copper alloys is discussed. It is shown that the combined use of metallography, electron probe micro-analysis and ion microscopy can obtain very useful information concerning fabrication technology and corrosion mechanisms of ancient metals. Especially the convenience of measuring ion micrographs for relatively rapid qualitative indication of phases and inclusions, which are of interest for the investigation of different corroded surfaces found on ancient bronzes, is outlined. The results of investigated of two bronze objects with a specific patina appearance are presented. (orig.)

Characterization of corroded bronze Ding from the Yin Ruins of China

International Nuclear Information System (INIS)

Ling, He; Qingrong, Zhao; Min, Gao

2007-01-01

This paper presents the result of scientific examinations carried out on the soil-buried archaeological bronzes Ding from Yin Ruins of China. Eight of typical fragments from different bronze Ding were selected as researched samples according to their deterioration characteristics. Optical microscopy (OM), scanning electron microscopy coupled with energy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to understand the corrosive morphological characteristics, to clear the nature of patina and to analyze the elementary composition of bronze Ding. The results indicated that it is not possible to distinguish the original lustrous metallic surface in most samples because of the corrosive crust. The substrate of bronze Ding contains74-86% Cu, 1.1-4.6% Pb, and 10-18% Sn, which is in agreement with the historical investigation in the ritual vessels of Shang time. Copper-containing compounds were the main constituents of natural patina: Cu 2 (OH) 3 Cl existed as corrosion product in all the powdery or crack surface; Cu 2 (OH) 2 CO 3 was the main corrosive product in a compact and hard corrosive surface. This study provides useful information for the restoration and protection of bronze Ding in Yin Ruins

Characterization of metallic surfaces in phosphorous-bronze ordered packings

International Nuclear Information System (INIS)

Sandru, Claudia; Titescu, Gh.

1997-01-01

Copper and its alloys, particularly the phosphorous bronze, are characterized by a high water wettability as compared with other materials. This feature led to utilization of phosphorous bronze in fabrication of contact elements, a packing type equipping the distillation columns. For heavy water separation by isotopic distillation under vacuum, ordered packings of phosphorous bronze networks were fabricated. The superior performances of these packings are determined by the material and also by the geometrical form and the state of the metallic surface. Thus, a procedure of evaluating the wettability has been developed, based on tests of the network material. The results of the tests constitute a criterion of rating the functional performances of packings, particularly of their efficiencies. Also, investigation techniques of the chemical composition and of the thickness of superficial layer on the packing were developed. It was found that the packing surface presents a layer of about 5-20 μm formed mainly by oxides of copper, tin, and, depending on the packing treatment, of oxides of other elements coming from the treatment agent. The paper presents characterization of phosphorous bronze treated with potassium permanganate, a specific treatment for improving the functional performances of the packings used in the heavy water concentration and re-concentration installations

Population genomics of Bronze Age Eurasia

Czech Academy of Sciences Publication Activity Database

Allentoft, M. E.; Sikora, M.; Sjogren, K.-G.; Rasmussen, S.; Rasmussen, M.; Stenderup, J.; Damgaard, P. B.; Schroeder, H.; Ahlström, T.; Vinner, L.; Malaspinas, A.-S.; Margaryan, A.; Higham, T.; Chivall, D.; Lynnerup, N.; Harvig, L.; Baron, J.; Della Casa, P.; Dabrowski, P.; Duffy, P. R.; Ebel, A. V.; Epimakhov, A.; Frei, K.; Furmanek, M.; Gralak, T.; Gromov, A.; Gronkiewicz, S.; Grupe, G.; Hajdu, T.; Jarysz, R.; Khartanovich, V.; Khokhlov, A.; Kiss, V.; Kolář, Jan; Kriiska, A.; Lasak, I.; Lonhgi, C.; McGlynn, G.; Merkevicius, A.; Merkyte, I.; Metspalu, M.; Mkrtchyan, R.; Moiseyev, V.; Paja, L.; Pilli, G.; Pokutta, D.; Pospieszny, L.; Price, D.; Saag, L.; Sablin, M.; Shishlina, N.; Smrčka, V.; Soenov, V. I.; Szeverenyi, V.; Tóth, G.; Trifanova, S. V.; Varul, L.; Vicze, M.; Yepiskoposyan, L.; Zhitenev, L.; Orlando, L.; Sicheritz-Ponten, T.; Brunak, S.; Nielsen, R.; Kristiansen, K.; Willerslev, E.

2015-01-01

Roč. 522, č. 7555 (2015), s. 167-172 ISSN 0028-0836 Institutional support: RVO:67985939 Keywords : genetics * migration * Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 38.138, year: 2015

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.

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

International Nuclear Information System (INIS)

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

2016-01-01

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. (paper)

Tungsten foil laminate for structural divertor applications - Joining of tungsten foils

Science.gov (United States)

Reiser, Jens; Rieth, Michael; Möslang, Anton; Dafferner, Bernhard; Hoffmann, Jan; Mrotzek, Tobias; Hoffmann, Andreas; Armstrong, D. E. J.; Yi, Xiaoou

2013-05-01

This paper is the fourth in our series on tungsten laminates. The aim of this paper is to discuss laminate synthesis, meaning the joining of tungsten foils. It is obvious that the properties of the tungsten laminate strongly depend on the combination of (i) interlayer and (ii) joining technology, as this combination defines (i) the condition of the tungsten foil after joining (as-received or recrystallised) as well as (ii) the characteristics of the interface between the tungsten foil and the interlayer (wettability or diffusion leading to a solid solution or the formation of intermetallics). From the example of tungsten laminates joined by brazing with (i) an eutectic silver copper brazing filler, (ii) copper, (iii) titanium, and (iv) zirconium, the microstructure will be discussed, with special focus on the interface. Based on our assumptions of the mechanism of the extraordinary ductility of tungsten foil we present three syntheses strategies and make recommendations for the synthesis of high temperature tungsten laminates.

Development and characterisation of a tungsten-fibre reinforced tungsten composite

International Nuclear Information System (INIS)

Riesch, Johann

2012-01-01

In tungsten-fibre reinforced tungsten, tungsten wire is combined with a tungsten matrix. The outstanding ductility of the fibres and extrinsic mechanisms of energy dissipation lead to an intense toughening. With extensive analytical and experimental investigations a manufacturing method based on chemical vapour infiltration is developed and first material is produced. The toughening mechanisms are shown by means of sophisticated mechanical experiments i.a. X-ray microtomography.

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

International Nuclear Information System (INIS)

Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo

2013-01-01

We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K 2 SO 4 electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO 4 ) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo [Korea Univ., Seoul (Korea, Republic of)

2013-08-15

We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K{sub 2}SO{sub 4} electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO{sub 4}) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium.

Propolis as a green corrosion inhibitor for bronze in weakly acidic solution

Science.gov (United States)

Varvara, Simona; Bostan, Roxana; Bobis, Otilia; Găină, Luiza; Popa, Florin; Mena, Vicente; Souto, Ricardo M.

2017-12-01

In the present work, the inhibitive action of natural propolis on bronze corrosion in a weakly acidic solution containing Na2SO4 and NaHCO3 at pH 5 was evaluated using multiscale electrochemical techniques, namely potentiodynamic polarization, electrochemical impedance spectroscopy and scanning vibrating electrode technique measurements. The major constituents of propolis were identified by HPLC. Surface characterization was performed by SEM-EDX and AFM analysis. Experiments were performed as a function of the propolis concentration and immersion time in the corrosive electrolyte. The obtained results showed that propolis presents good anticorrosive properties on bronze, acting as a mixed-type inhibitor, but its protective effectiveness is time-dependent. The highest inhibiting efficiency of 98.9% was obtained in the presence of 100 ppm propolis, after about 12 h of exposure to inhibitor-containing electrolyte through the stabilization of Cu2O on the bronze surface. The inhibitive properties of propolis on bronze corrosion are likely due to the adsorption of its main constituents (flavonoids and phenolic compounds), through the oxygen atoms in their functional groups and aromatic rings, which have been evidenced by FT-IR spectra. The adsorption of propolis on bronze was found to follow Langmuir adsorption isotherm.

Portable XRF on Prehistoric Bronze Artefacts: Limitations and Use for the Detection of Bronze Age Metal Workshops

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

2017-01-01

sections were analysed using a scanning electron microscope (SEM). Results from the corrosion crust of copper-tin alloys, and the change measured within the elemental composition from the bulk metal to the surface, greatly influenced the interpretation of the second data set, which was measured using......Two different scientific analyses—one destructive and one non destructive—were conducted on two separate groups of bronze ornaments dating from 1500–1100 BC to investigate, amongst other traits, the metal composition of their copper-tin alloys. One group of artefacts was sampled, and polished thin...... a handheld X-ray fluorescence (XRF) device. The surface of corroded bronze ornaments consists mostly of copper carbonates, oxides, and chlorides. Chemical processes, such as decuprification, change the element composition in such a manner that the original alloy cannot be traced with a non-destructive method...

Late Bronze Age hoard studied by PIXE

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Neira, P.C., E-mail: carolina.gutierrez@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Zucchiatti, A., E-mail: alessandro.zucchiatti@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Montero-Ruiz, I., E-mail: ignacio.montero@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Vilaca, R., E-mail: rvilaca@fl.uc.pt [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Bottaini, C., E-mail: keret18@yahoo.it [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Gener, M., E-mail: marc.gener@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Climent-Font, A., E-mail: acf@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Department of Applied Physics, Universidad Autonoma de Madrid, Campus Cantobalanco, E-28049 Madrid (Spain)

2011-12-15

The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising four socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni, and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.

Tungsten foil laminate for structural divertor applications – Joining of tungsten foils

Energy Technology Data Exchange (ETDEWEB)

Reiser, Jens, E-mail: jens.reiser@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-AWP) (Germany); Rieth, Michael; Möslang, Anton; Dafferner, Bernhard; Hoffmann, Jan [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-AWP) (Germany); Mrotzek, Tobias; Hoffmann, Andreas [PLANSEE SE, Reutte (Austria); Armstrong, D.E.J.; Yi, Xiaoou [University of Oxford, Department of Materials (United Kingdom)

2013-05-15

This paper is the fourth in our series on tungsten laminates. The aim of this paper is to discuss laminate synthesis, meaning the joining of tungsten foils. It is obvious that the properties of the tungsten laminate strongly depend on the combination of (i) interlayer and (ii) joining technology, as this combination defines (i) the condition of the tungsten foil after joining (as-received or recrystallised) as well as (ii) the characteristics of the interface between the tungsten foil and the interlayer (wettability or diffusion leading to a solid solution or the formation of intermetallics). From the example of tungsten laminates joined by brazing with (i) an eutectic silver copper brazing filler, (ii) copper, (iii) titanium, and (iv) zirconium, the microstructure will be discussed, with special focus on the interface. Based on our assumptions of the mechanism of the extraordinary ductility of tungsten foil we present three syntheses strategies and make recommendations for the synthesis of high temperature tungsten laminates.

High-energy, high-rate consolidation of tungsten and tungsten-based composite powders

Energy Technology Data Exchange (ETDEWEB)

Raghunathan, S.K.; Persad, C.; Bourell, D.L.; Marcus, H.L. (Center for Materials Science and Engineering, Univ. of Texas, Austin (USA))

1991-01-20

Tungsten and tungsten-based heavy alloys are well known for their superior mechanical properties at elevated temperatures. However, unalloyed tungsten is difficult to consolidate owing to its very high melting temperature (3683 K). The additions of small amounts of low-melting elements such as iron, nickel, cobalt and copper, facilitate the powder processing of dense heavy alloys at moderate temperatures. Energetic high-current pulses have been used recently for powder consolidation. In this paper, the use of a homopolar generator as a power source to consolidate selected tungsten and tungsten-based alloys is examined. Various materials were consolidated including unalloyed tungsten, W-Nb, W-Ni, and tungsten heavy alloy with boron carbide. The effect of process parameters such as pressure and specific energy input on the consolidation of different alloy systems is described in terms of microstructure and property relationships. (orig.).

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.

Gas-driven permeation of deuterium through tungsten and tungsten alloys

Energy Technology Data Exchange (ETDEWEB)

Buchenauer, Dean A., E-mail: dabuche@sandia.gov [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States); Karnesky, Richard A. [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States); Fang, Zhigang Zak; Ren, Chai [University of Utah, Department of Metallurgical Engineering, Salt Lake City, UT 84112 (United States); Oya, Yasuhisa [Shizuoka University, Graduate School of Science, Shizuoka (Japan); Otsuka, Teppei [Kyushu University, Department of Advanced Energy Engineering Science, Fukuoka (Japan); Yamauchi, Yuji [Hokkaido University, Third Division of Quantum Science and Engineering, Faculty of Engineering, Sapporo (Japan); Whaley, Josh A. [Sandia National Laboratories, Energy Innovation Department, Livermore, CA 94550 (United States)

2016-11-01

Highlights: • We have designed and performed initial studies on a high temperature gas-driven permeation cell capable of operating at temperatures up to 1150 °C and at pressures between 0.1–1 atm. • Permeation measurements on ITER grade tungsten compare well with past studies by Frauenfelder and Zahkarov in the temperature range from 500 to 1000 °C. • First permeation measurements on Ti dispersoid-strengthened ultra-fine grained tungsten show higher permeation at 500 °C, but very similar permeation with ITER tungsten at 1000 °C. Diffusion along grain boundaries may be playing a role for this type of material. - Abstract: To address the transport and trapping of hydrogen isotopes, several permeation experiments are being pursued at both Sandia National Laboratories (deuterium gas-driven permeation) and Idaho National Laboratories (tritium gas- and plasma-driven tritium permeation). These experiments are in part a collaboration between the US and Japan to study the performance of tungsten at divertor relevant temperatures (PHENIX). Here we report on the development of a high temperature (≤1150 °C) gas-driven permeation cell and initial measurements of deuterium permeation in several types of tungsten: high purity tungsten foil, ITER-grade tungsten (grains oriented through the membrane), and dispersoid-strengthened ultra-fine grain (UFG) tungsten being developed in the US. Experiments were performed at 500–1000 °C and 0.1–1.0 atm D{sub 2} pressure. Permeation through ITER-grade tungsten was similar to earlier W experiments by Frauenfelder (1968–69) and Zaharakov (1973). Data from the UFG alloy indicates marginally higher permeability (< 10×) at lower temperatures, but the permeability converges to that of the ITER tungsten at 1000 °C. The permeation cell uses only ceramic and graphite materials in the hot zone to reduce the possibility for oxidation of the sample membrane. Sealing pressure is applied externally, thereby allowing for elevation

Determination of tungsten in high-alloy steels and heat resisting alloys by isotope dilution-spark source mass spectrometry

International Nuclear Information System (INIS)

Saito, Morimasa; Yamada, Kei; Okochi, Haruno; Hirose, Fumio

1983-01-01

Tungsten in high-alloy steels and heat-resisting alloys was determined by isotope dilution method combined with spark source mass spectrometry by using 183 W enriched tungsten. The spike solution was prepared by fusing tungsten trioxide in sodium carbonate. A high-alloy steel sample was dissolved in the mixture of sulfuric acid and phosphoric acid together with the spike solution; a sample of heat resisting alloy was similarly dissolved in the mixture of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. The solution was evaporated to give dense white fumes. Tungsten was separated from the residue by a conventional cinchonine salt-precipitation method. The salt was ignited, and the residue was mixed with graphite powder and pressed into electrodes. The isotope 183 W and 184 W were measured. The method was applied to the determination of tungsten in JSS and NBS standard high-alloy steels and JAERI standard nickel- and NBS standard cobalt-base heat resisting alloys containing more than 0.05% tungsten. The results were obtained with satisfactory precision and accuracy. However, the results obtained for JSS standard high- speed steels containing molybdenum tended to be significantly lower than the certified values. (author)

Information extraction from FN plots of tungsten microemitters

Energy Technology Data Exchange (ETDEWEB)

Mussa, Khalil O. [Department of Physics, Mu' tah University, Al-Karak (Jordan); Mousa, Marwan S., E-mail: mmousa@mutah.edu.jo [Department of Physics, Mu' tah University, Al-Karak (Jordan); Fischer, Andreas, E-mail: andreas.fischer@physik.tu-chemnitz.de [Institut für Physik, Technische Universität Chemnitz, Chemnitz (Germany)

2013-09-15

Tungsten based microemitter tips have been prepared both clean and coated with dielectric materials. For clean tungsten tips, apex radii have been varied ranging from 25 to 500 nm. These tips were manufactured by electrochemical etching a 0.1 mm diameter high purity (99.95%) tungsten wire at the meniscus of two molar NaOH solution. Composite micro-emitters considered here are consisting of a tungsten core coated with different dielectric materials—such as magnesium oxide (MgO), sodium hydroxide (NaOH), tetracyanoethylene (TCNE), and zinc oxide (ZnO). It is worthwhile noting here, that the rather unconventional NaOH coating has shown several interesting properties. Various properties of these emitters were measured including current–voltage (IV) characteristics and the physical shape of the tips. A conventional field emission microscope (FEM) with a tip (cathode)–screen (anode) separation standardized at 10 mm was used to electrically characterize the electron emitters. The system was evacuated down to a base pressure of ∼10{sup −8}mbar when baked at up to ∼180°C overnight. This allowed measurements of typical field electron emission (FE) characteristics, namely the IV characteristics and the emission images on a conductive phosphorus screen (the anode). Mechanical characterization has been performed through a FEI scanning electron microscope (SEM). Within this work, the mentioned experimental results are connected to the theory for analyzing Fowler–Nordheim (FN) plots. We compared and evaluated the data extracted from clean tungsten tips of different radii and determined deviations between the results of different extraction methods applied. In particular, we derived the apex radii of several clean and coated tungsten tips by both SEM imaging and analyzing FN plots. The aim of this analysis is to support the ongoing discussion on recently developed improvements of the theory for analyzing FN plots related to metal field electron emitters, which in

Information extraction from FN plots of tungsten microemitters

International Nuclear Information System (INIS)

Mussa, Khalil O.; Mousa, Marwan S.; Fischer, Andreas

2013-01-01

Tungsten based microemitter tips have been prepared both clean and coated with dielectric materials. For clean tungsten tips, apex radii have been varied ranging from 25 to 500 nm. These tips were manufactured by electrochemical etching a 0.1 mm diameter high purity (99.95%) tungsten wire at the meniscus of two molar NaOH solution. Composite micro-emitters considered here are consisting of a tungsten core coated with different dielectric materials—such as magnesium oxide (MgO), sodium hydroxide (NaOH), tetracyanoethylene (TCNE), and zinc oxide (ZnO). It is worthwhile noting here, that the rather unconventional NaOH coating has shown several interesting properties. Various properties of these emitters were measured including current–voltage (IV) characteristics and the physical shape of the tips. A conventional field emission microscope (FEM) with a tip (cathode)–screen (anode) separation standardized at 10 mm was used to electrically characterize the electron emitters. The system was evacuated down to a base pressure of ∼10 −8 mbar when baked at up to ∼180°C overnight. This allowed measurements of typical field electron emission (FE) characteristics, namely the IV characteristics and the emission images on a conductive phosphorus screen (the anode). Mechanical characterization has been performed through a FEI scanning electron microscope (SEM). Within this work, the mentioned experimental results are connected to the theory for analyzing Fowler–Nordheim (FN) plots. We compared and evaluated the data extracted from clean tungsten tips of different radii and determined deviations between the results of different extraction methods applied. In particular, we derived the apex radii of several clean and coated tungsten tips by both SEM imaging and analyzing FN plots. The aim of this analysis is to support the ongoing discussion on recently developed improvements of the theory for analyzing FN plots related to metal field electron emitters, which in

Information extraction from FN plots of tungsten microemitters.

Science.gov (United States)

Mussa, Khalil O; Mousa, Marwan S; Fischer, Andreas

2013-09-01

Tungsten based microemitter tips have been prepared both clean and coated with dielectric materials. For clean tungsten tips, apex radii have been varied ranging from 25 to 500 nm. These tips were manufactured by electrochemical etching a 0.1 mm diameter high purity (99.95%) tungsten wire at the meniscus of two molar NaOH solution. Composite micro-emitters considered here are consisting of a tungsten core coated with different dielectric materials-such as magnesium oxide (MgO), sodium hydroxide (NaOH), tetracyanoethylene (TCNE), and zinc oxide (ZnO). It is worthwhile noting here, that the rather unconventional NaOH coating has shown several interesting properties. Various properties of these emitters were measured including current-voltage (IV) characteristics and the physical shape of the tips. A conventional field emission microscope (FEM) with a tip (cathode)-screen (anode) separation standardized at 10 mm was used to electrically characterize the electron emitters. The system was evacuated down to a base pressure of ∼10(-8) mbar when baked at up to ∼180 °C overnight. This allowed measurements of typical field electron emission (FE) characteristics, namely the IV characteristics and the emission images on a conductive phosphorus screen (the anode). Mechanical characterization has been performed through a FEI scanning electron microscope (SEM). Within this work, the mentioned experimental results are connected to the theory for analyzing Fowler-Nordheim (FN) plots. We compared and evaluated the data extracted from clean tungsten tips of different radii and determined deviations between the results of different extraction methods applied. In particular, we derived the apex radii of several clean and coated tungsten tips by both SEM imaging and analyzing FN plots. The aim of this analysis is to support the ongoing discussion on recently developed improvements of the theory for analyzing FN plots related to metal field electron emitters, which in particular

Production and properties of bronze based cellular materials

International Nuclear Information System (INIS)

Strobl, S.; Danninger, H.

2001-01-01

For production of lightweight components, cellular materials offer attractive potential. Here, manufacturing of sintered bodies from bronze hollow spheres is described. The process starts with fabrication of hollow copper particles by cementation of Cu on iron particles. The still fragile Cu shells are consolidated by coating with Sn and subsequent gravity sintering. The resulting specimens exhibit a closed cell bronze structure with rather consistent morphology and cell wall thickness. The apparent density may range between 1.5 and 3.0 gcm -3 and can be controlled by variation of particle size and wall thickness. The mechanical behavior of the structures esp. during compressive loading is described and related to the microstructural parameters. (author)

Experimental investigations of the frictional and wear behavior of tungsten carbide cermet ball bearings under axial load in liquid sodium

International Nuclear Information System (INIS)

Kleefeldt, K.W.

1976-01-01

The paper describes part of the R and D work performed on ball bearings operated in a liquid sodium environment and tested under conditions which are felt to be representative for high precision mechanisms in LMFBR's. After a short introduction, mainly dealing with the experimental results of other authors, a description will be given of the test facility, the test procedure, the ball bearings and the basis for the selection of the materials. The paper covers the experimental phase, which has been carried out in two steps. In the first phase material screening tests demonstrated the tungsten-carbide-cobalt cermet to be superior to the other materials tested with respect to friction and wear. This material, therefore, was selected for a more detailed parameter test programme during phase 2. Up to now a series of tests have been performed with bearing load and speed as parameters, indicating that fatigue is the life limiting factor. It shows that a life-load relationship, similar to that known for conventional ball bearing technology, also seems appropriate for the test conditions and environment investigated here

Hydrogen detector for sodium cooled reactors

International Nuclear Information System (INIS)

Roy, P.; Rodgers, D.N.

1975-01-01

An improved hydrogen detector for use in sodium cooled reactors is described. The improved detector basically comprises a diffusion tube of either pure nickel or stainless steel having a coating on the vacuum side (inside) of a thin layer of refractory metal, e.g., tungsten or molybdenum. The refractory metal functions as a diffusion barrier in the path of hydrogen diffusing from the sodium on the outside of the detector into the vacuum on the inside, thus by adjusting the thickness of the coating, it is possible to control the rate of permeation of hydrogen through the tube, thereby providing a more stable detector. (U.S.)

Further development of the tungsten-fibre reinforced tungsten composite

Energy Technology Data Exchange (ETDEWEB)

Gietl, Hanns; Hoeschen, Till; Riesch, Johann [Max-Planck-Institut fuer Plasmaphysik, 85748 Garching (Germany); Aumann, Martin; Coenen, Jan [Forschungszentrum Juelich, IEK4, 52425 Juelich (Germany); Huber, Philipp [Lehrstuhl fuer Textilmaschinenbau und Institut fuer Textiltechnik (ITA), 52062 Aachen (Germany); Neu, Rudolf [Max-Planck-Institut fuer Plasmaphysik, 85748 Garching (Germany); Technische Universitaet Muenchen, 85748 Garching (Germany)

2016-07-01

For the use in a fusion device tungsten has a unique property combination. The brittleness below the ductile-to-brittle transition temperature and the embrittlement during operation e.g. by overheating, neutron irradiation are the main drawbacks for the use of pure tungsten. Tungsten fibre-reinforced tungsten composites utilize extrinsic mechanisms to improve the toughness. After proofing that this idea works in principle the next step is the conceptual proof for the applicability in fusion reactors. This will be done by producing mock-ups and testing them in cyclic high heat load tests. For this step all constituents of the composite, which are fibre, matrix and interface, and all process steps need to be investigated. Tungsten fibres are investigated by means of tension tests to find the optimum diameter and pretreatment. New interface concepts are investigated to meet the requirements in a fusion reactor, e.g. high thermal conductivity, low activation. In addition weaving processes are evaluated for their use in the fibre preform production. This development is accompanied by an extensive investigation of the materials properties e.g. single fibre tension tests.

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.

Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

International Nuclear Information System (INIS)

Rotaru, Ileana; Varvara, Simona; Gaina, Luiza; Muresan, Liana Maria

2014-01-01

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 HOMO and E LUMO and HOMO–LUMO energy gap were used for correlation with the corrosion data

Deuterium trapping in tungsten

Science.gov (United States)

Poon, Michael

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Deuterium trapping in tungsten

International Nuclear Information System (INIS)

Poon, M.

2004-01-01

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. . Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D 2 molecules inside the void with a trap energy of 1.2 eV. . Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Deuterium trapping in tungsten

Energy Technology Data Exchange (ETDEWEB)

Poon, M

2004-07-01

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. . Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D{sub 2} molecules inside the void with a trap energy of 1.2 eV. . Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D

Clay Corner: Recreating Chinese Bronze Vessels.

Science.gov (United States)

Gamble, Harriet

1998-01-01

Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

21 CFR 73.1646 - Bronze powder.

Science.gov (United States)

2010-04-01

... percent. Maximum particle size 45µ (95 percent minimum). Aluminum, zinc, tin, and copper content shall be based on the weight of the dried powder after being thoroughly washed with ether. (c) Uses and restrictions. Bronze powder may be safely used in color externally applied drugs, including those intended for...

Lead isotope approach to the understanding of early Japanese bronze culture

International Nuclear Information System (INIS)

Mabuchi, H.; Hirao, Y.

1985-01-01

For several years, the authors have used lead isotope analysis to investigate extensively the provenance of ancient bronze or copper artifacts which had been excavated mainly from Japanese archaeological sites. The results have been published item by item in several relevant Japanese journals. This review is intended to give an account which will review the whole work relating early Japanese bronze culture to Chinese and Korean cultures through lead isotope study. (author)

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

Science.gov (United States)

2010-09-22

... DEPARTMENT OF STATE [Public Notice 7181] Culturally Significant Objects Imported for Exhibition Determinations: ``Ancient Chinese Bronzes From the Shouyang Studio: The Katherine and George Fan Collection... ``Ancient Chinese Bronzes from the Shouyang Studio: The Katherine and George Fan Collection,'' imported from...

Investigations on dry sliding of laser cladded aluminum bronze

Directory of Open Access Journals (Sweden)

Freiße Hannes

2016-01-01

Full Text Available The aim of this study was to investigate the tribological behaviour of laser cladded aluminum bronze tool surfaces for dry metal forming. In a first part of this work a process window for cladding aluminum bronze on steel substrate was investigated to ensure a low dilution. Therefore, the cladding speed, the powder feed rate, the laser power and the distance between the process head and the substrate were varied. The target of the second part was to investigate the influence of different process parameters on the tribological behaviour of the cladded tracks. The laser claddings were carried out on both aluminum bronze and cold work tool steel as substrate materials. Two different particle sizes of the cladding powder material were used. The cladding speed was varied and a post-processing laser remelting treatment was applied. It is shown that the tribological behaviour of the surface in a dry oscillating ball-on-plate test is highly dependent on the substrate material. In the third part a deep drawing tool was additively manufactured by direct laser deposition. Furthermore, the tool was applied to form circular cups with and without lubrication.

Mechanism of the electrochemical hydrogen reaction on smooth tungsten carbide and tungsten electrodes

International Nuclear Information System (INIS)

Wiesener, K.; Winkler, E.; Schneider, W.

1985-01-01

The course of the electrochemical hydrogen reaction on smooth tungsten-carbide electrodes in hydrogen saturated 2.25 M H 2 SO 4 follows a electrochemical sorption-desorption mechanism in the potential range of -0.4 to +0.1 V. At potentials greater than +0.1 V the hydrogen oxidation is controlled by a preliminary chemical sorption step. Concluding from the similar behaviour of tungsten-carbide and tungsten electrodes after cathodic pretreatment, different tungsten oxides should be involved in the course of the hydrogen reaction on tungsten carbide electrodes. (author)

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.

Characterisation of Late Bronze Age large size shield nails by EDXRF, micro-EDXRF and X-ray digital radiography

International Nuclear Information System (INIS)

Figueiredo, E.; Araujo, M.F.; Silva, R.J.C.; Senna-Martinez, J.C.; Ines Vaz, J.L.

2011-01-01

In the present study six exceptional large size metallic nails, a dagger and a sickle from the Late Bronze Age archaeological site of Figueiredo das Donas (Central Portugal) have been analysed by EDXRF, micro-EDXRF and X-ray digital radiography for the study of material composition and technology of fabrication. The combination of these analytical and examination techniques showed that all artefacts are made of bronze with As, Sb and Pb impurities, and that the nails were most likely manufactured using the casting-on technique. These results reinforce the use of binary bronze by Late Bronze Age in the region, and the incorporation of new fabrication technologies that resulted from ancient spheres of interaction. - Highlights: → EDXRF, micro-EDXRF and X-ray digital radiography in cultural heritage studies. → Archaeometallurgical study of a Late Bronze Age artefact collection from Portugal. → Practise of a specific and traditional bronze metallurgy. → Appearance of technological innovations as the casting-on technique.

Tensile behaviour of drawn tungsten wire used in tungsten fibre-reinforced tungsten composites

International Nuclear Information System (INIS)

Riesch, J; Feichtmayer, A; Fuhr, M; Gietl, H; Höschen, T; Neu, R; Almanstötter, J; Coenen, J W; Linsmeier, Ch

2017-01-01

In tungsten fibre-reinforced tungsten composites (W f /W) the brittleness problem of tungsten is solved by utilizing extrinsic toughening mechanisms. The properties of the composite are very much related to the properties of the drawn tungsten wire used as fibre reinforcements. Its high strength and capability of ductile deformation are ideal properties facilitating toughening of W f /W. Tensile tests have been used for determining mechanical properties and study the deformation and the fracture behaviour of the wire. Tests of as-fabricated and straightened drawn wires with a diameter between 16 and 150 μ m as well as wire electrochemically thinned to a diameter of 5 μ m have been performed. Engineering stress–strain curves and a microscopic analysis are presented with the focus on the ultimate strength. All fibres show a comparable stress–strain behaviour comprising necking followed by a ductile fracture. A reduction of the diameter by drawing leads to an increase of strength up to 4500 MPa as a consequence of a grain boundary hardening mechanism. Heat treatment during straightening decreases the strength whereas electrochemical thinning has no significant impact on the mechanical behaviour. (paper)

ISOTOPES, PLANTS, AND RESERVOIR EFFECTS : CASE STUDY FROM THE CASPIAN STEPPE BRONZE AGE

NARCIS (Netherlands)

Shishlina, N.; Zazovskaya, E.; van der Plicht, J.; Sevastyanov, V.; Boaretto, E.; Rebollo Franco, N.R.

2012-01-01

Bronze Age human and animal bone collagen from several steppe Bronze Age cultures (i.e. Early Catacomb, East and West Manych Catacomb, and Lola cultures) shows large variations in delta C-13 and delta N-15 values. In general, we observed that the older the sample, the lower the delta C-13 and delta

Portable EDXRF investigation of the patinas on the Riace Bronzes

Energy Technology Data Exchange (ETDEWEB)

Buccolieri, Giovanni, E-mail: giovanni.buccolieri@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy); Buccolieri, Alessandro, E-mail: alessandro.buccolieri@unisalento.it [Università del Salento, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, via Monteroni, 73100 Lecce (Italy); Donati, Paola, E-mail: paola.donati@beniculturali.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Marabelli, Maurizio, E-mail: maurizio.marabelli@libero.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Castellano, Alfredo, E-mail: alfredo.castellano@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy)

2015-01-15

This paper summarizes the experimental results concerning the Energy Dispersive X-ray Fluorescence (EDXRF) analysis of patinas on two Riace Bronzes, kept in the National Archaeological Museum of Reggio Calabria (Calabria, Southern Italy). The two large Greek sculptures, famous nude bearded warriors both dated in the fifth century BC, are without a doubt, two masterpieces of inestimable historic and artistic value. EDXRF survey had the aim to determinate the chemical composition of the surface of these two bronze statues and to discriminate their different patinas. In particular, the concentration of sulphur, chlorine, tin, manganese, iron, copper, zinc and lead was determined by using a portable apparatus. Multivariate statistical analysis was carried out in order to identify possible correlations and/or differences of elemental composition among the patinas of these two statues. The information obtained made it possible to improve knowledge about the patinas of the Riace Bronzes, and this may help further studies and subsequent methods of restoration and/or of preservation of the two celebrated Greek sculptures.

Thermodynamics of the hydrogen-carbon-oxygen-tungsten system, as applied to the manufacture of tungsten and tungsten carbide

International Nuclear Information System (INIS)

Schwenke, G.K.

2001-01-01

The thermodynamics of the quaternary hydrogen-carbon oxygen-tungsten system and its binary and ternary sub-systems are reviewed. Published thermodynamic data are evaluated, and expression for free energies of formation are chosen. These expressions are integrated with and equilibrium-calculating algorithm, producing a powerful tool for understanding and improving the manufacture of tungsten and tungsten carbide. Three examples are presented: reduction/carburization of tungstic oxide with hydrogen, carbon, and methane. (author)

Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium (VI)-I: comparison of thermometric and potentiometric titration curves.

Science.gov (United States)

Kiba, N; Takeuchi, T

1973-09-01

A new twin-cell thermometric titrator has been devised and used for thermometric titration of solutions of sodium molybdate, sodium tungstate, sodium orthovanadate, ammonium metavanadate, and potassium chromate with perchloric acid. The thermometric titration curves were compared with corresponding pH-titration curves for elucidation of the reactions occurring in the titrations. Thermometric titrimetric methods have been developed for the determination of tungsten, vanadium and chromium.

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.

Izumo and the East Asian Bronze Culture%出云与东亚的青铜文化

Institute of Scientific and Technical Information of China (English)

王巍

2003-01-01

The origin of bronzes in Yayoi Japan can be traced to their counterparts in Xia-Shang-Zhou China. It must have happened that ancient Chinese bronze weapons and small bells used aspractical implements were first spread into Japan through northeastern China and the Korean Peninsulaand then developed gradually into bronzes exclusively for sacrificial use. Among the bronzes unearthed inbatches from hoards in the Izumo area within the coastland of the Sea of Japan, the spearheads may havebeen made in the north of Kyushu, the small bells must have come from the Kinai region, and the over300 swords were probably local products. The repeated discovery of Yayoi bronze hoards in the Izumoarea suggests that this region was absolutely not an unpopulated land. On the contrary, as a very im-portant district, it should be fully affirmed to have played a considerable role in the development of an-cient Japanese history.

Tribaloy alloy reinforced tin-bronze composite coating for journal bearing applications

International Nuclear Information System (INIS)

Gao, F.; Liu, R.; Wu, X.J.

2011-01-01

This article presents an experimental study of the tribological behavior of a tin/bronze-based composite coating. The improved-ductility Tribaloy alloy (T-401) particles are selected as the reinforcement. This coating is made on the bushing of planet journals used in aerospace engines, deposited with the high velocity oxygen fuel (HVOF) thermal spray technique. The tribological properties such as friction and wear resistance of the coated bushing are investigated under the WAMsc3 Sliding Contact Test, along with the leaded tin/bronze bushing tested for comparison. The testing results show that the bushing coated with the composite exhibits superior tribological properties to the leaded tin/bronze bushing in that the former runs longer before the friction coefficient reaches 0.5 and also leads a to lower wear rate than the latter. The experimental results and wear mechanisms of these two bushings are discussed with the assistance of worn surface analyses using scanning electron microscopy (SEM).

Boiling heat transfer on single phosphor bronze and copper mesh microstructures

Directory of Open Access Journals (Sweden)

Orman Łukasz J.

2014-03-01

Full Text Available The paper presents experimental results of boiling heat transfer of distilled water and ethyl alcohol on surfaces covered with single layers of wire mesh structures made of phosphor bronze and copper. For each material two kinds of structures have been considered (higher and lower in order to determine the impact of the height of the structure on boiling heat transfer. The wire diameter of the copper meshes was 0,25 mm and 0,32 mm, while of the bronze meshes: 0,20 mm and 0,25 mm. The structures had the same mesh aperture (distance between the wires – 0,50 mm for copper and 0,40 for bronze but different wire diameter and, consequently, different height of the layers. The tests have been performed under ambient pressure in the pool boiling mode. The obtained results indicate a visible impact of the layer height on the boiling heat transfer performance of the analysed microstructures.

Tungsten foil laminate for structural divertor applications – Analyses and characterisation of tungsten foil

International Nuclear Information System (INIS)

Reiser, Jens; Rieth, Michael; Dafferner, Bernhard; Hoffmann, Andreas; Yi Xiaoou; Armstrong, David E.J.

2012-01-01

It has been attempted for several years to synthesise a tungsten material with a low brittle-to-ductile transition temperature and a high fracture toughness that can be used for structural parts. It was shown in our previous work that tungsten foil is ductile at room temperature and that this ductility can be transformed to bulk by synthesising a tungsten laminate. In this work we want to focus on tungsten foil and assess the microstructure as well as the mechanical properties of the foil. The assessment of the microstructure of 0.1 mm tungsten foil will be performed using electron microscopy. It will be shown that the grains of the tungsten foil have a dimension of 0.5 μm × 3 μm × 15 μm and a clear texture in (1 0 0) 〈0 1 1〉. This texture becomes even more pronounced by annealing. Three-point-bending tests with tungsten foil, as-received, will define the barriers: ductile at room temperature and brittle in liquid nitrogen (−196 °C). This shows that the ductility is a thermally activated process. Recrystallised tungsten foil (annealed for 1 h/2700 °C) shows ductile material behaviour at 200 °C. The paper closes with a discussion on the reasons of the ductility of 0.1 mm tungsten foil. These might be the ultra fine grained (UFG) microstructure or, in other words, a nano microstructure (see tungsten foil as-received), the high amount of mobile edge dislocations, and/or the foil effect, which means that dislocations can move to the surface and are annihilated (see tungsten foil recrystallised).

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.

Potentiometric determination of the tungsten content of tantalum-tungsten alloys with chromium II

International Nuclear Information System (INIS)

Gavra, Z.; Ronen, S.; Levin, R.

1977-05-01

A method was developed for the potentiometric determination of the tungsten content of tantalum-tungsten alloys of different compositions. These were dissolved under conditions that enabled the tungsten content to be determined with chromium (II). Phosphoric acid was selected as a suitable complexing agent for the prevention of the precipitation of tungsten and tantalum compounds. The use of chromium (II) required an oxygen-tight system and therefore the work was carried out in suitable vessels for storage and tritation

High temperature diffusion of hafnium in tungsten and a tungsten-hafnium carbide alloy

International Nuclear Information System (INIS)

Ozaki, Y.; Zee, R.H.

1994-01-01

Refractory metals and ceramics are used extensively in energy systems due to their high temperature properties. This is particularly important in direct conversion systems where thermal to electric conversion efficiency is a direct function of temperature. Tungsten, which has the highest melting temperature among elemental metals, does not possess sufficient creep resistance at temperature above 1,600 K. Different dispersion strengthened tungsten alloys have been developed to extend the usefulness of tungsten to higher temperatures. One of these alloys, tungsten with 0.4 mole percent of finely dispersed HfC particles (W-HfC), has the optimum properties for high temperature applications. Hafnium carbide is used as the strengthening agent due to its high chemical stability and its compatibility with tungsten. The presence of HfC particles retards the rate of grain growth as well as restricting dislocation motion. Both of which are beneficial for creep resistance. The long term behavior of this alloy depends largely on the evolution of its microstructure which is governed by the diffusion of its constituents. Data on the diffusion of carbon in tungsten and tungsten self-diffusion are available, but no direct measurements have been made on the diffusion of hafnium in tungsten. The only diffusion data available are estimated from a coarsening study and these data are highly unreliable. In this study, the diffusion behavior of hafnium in pure tungsten and in a W-HfC alloy was directly measured by means of Secondary Ion Mass Spectroscopy (SIMS). The selection of the W-HfC alloy is due to its importance in high temperature engineering applications, and its higher recrystallization temperature. The presence of HfC particles in tungsten restricts grain growth resulting in better high temperature creep resistance. The higher recrystallization temperature allows measurements to be made over a wider range of temperatures at a relatively constant grain size

Influence of Metal-Coated Graphite Powders on Microstructure and Properties of the Bronze-Matrix/Graphite Composites

Science.gov (United States)

Zhao, Jian-hua; Li, Pu; Tang, Qi; Zhang, Yan-qing; He, Jian-sheng; He, Ke

2017-02-01

In this study, the bronze-matrix/x-graphite (x = 0, 1, 3 and 5%) composites were fabricated by powder metallurgy route by using Cu-coated graphite, Ni-coated graphite and pure graphite, respectively. The microstructure, mechanical properties and corrosive behaviors of bronze/Cu-coated-graphite (BCG), bronze/Ni-coated-graphite (BNG) and bronze/pure-graphite (BPG) were characterized and investigated. Results show that the Cu-coated and Ni-coated graphite could definitely increase the bonding quality between the bronze matrix and graphite. In general, with the increase in graphite content in bronze-matrix/graphite composites, the friction coefficients, ultimate density and wear rates of BPG, BCG and BNG composites all went down. However, the Vickers microhardness of the BNG composite would increase as the graphite content increased, which was contrary to the BPG and BCG composites. When the graphite content was 3%, the friction coefficient of BNG composite was more stable than that of BCG and BPG composites, indicating that BNG composite had a better tribological performance than the others. Under all the values of applied loads (10, 20, 40 and 60N), the BCG and BNG composites exhibited a lower wear rate than BPG composite. What is more, the existence of nickel in graphite powders could effectively improve the corrosion resistance of the BNG composite.

Sodium-cooled Fast Reactor Cores using Uranium-Free Metallic Fuels for Maximizing TRU Support Ratio

International Nuclear Information System (INIS)

You, WuSeung; Hong, Ser Gi

2014-01-01

The depleted uranium plays important roles in the SFR burner cores because it substantially contributes to the inherent safety of the core through the negative Doppler coefficient and large delayed neutron. However, the use of depleted uranium as a diluent nuclide leads to a limited value of TRU support ratio due to the generation of TRUs through the breeding. In this paper, we designed sodium cooled fast reactor (SFR) cores having uranium-free fuels 3,4 for maximization of TRU consumption rate. However, the uranium-free fuelled burner cores can be penalized by unacceptably small values of the Doppler coefficient and small delayed neutron fraction. In this work, metallic fuels of TRU-(W or Ni)-Zr are considered to improve the performances of the uranium-free cores. The objective of this work is to consistently compare the neutronic performances of uranium-free sodium cooled fast reactor cores having TRU-Zr metallic fuels added with Ni or W and also to clarify what are the problematic features to be resolved. In this paper, a consistent comparative study of 400MWe sodium cooled burner cores having uranium-based fuels and uranium-free fuels was done to analyze the relative core neutronic features. Also, we proposed a uranium-free metallic fuel based on Nickel. From the results, it is found that tungsten-based uranium-free metallic fuel gives large negative Doppler coefficient due to high resonance of tungsten isotopes but this core has large sodium void worth and small effective delayed neutron fraction while the nickel-based uranium-free metallic fuelled core has less negative Doppler coefficient but smaller sodium void worth and larger effective delayed neutron fraction than the tungsten-based one. On the other hand, the core having TRU-Zr has very high burnup reactivity swing which may be problematic in compensating it using control rods and the least negative Doppler coefficient

Plasma etching of patterned tungsten

International Nuclear Information System (INIS)

Franssila, S.

1993-01-01

Plasma etching of tungsten is discussed from the viewpoint of thin film structure and integrated circuit process engineering. The emphasis is on patterned tungsten etching for silicon device and X-ray mask fabrication. After introducing tungsten etch chemistries and mechanisms, microstructural aspects of tungsten films (crystal structure, grain size, film density, defects, impurities) in relation to etching are discussed. Approaches to etch process optimization are presented, and the current state-of-the-art of patterned tungsten etching is reviewed. (orig.)

Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyeyoun [Division of Restoration Technology, National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of); Cho, Namchul, E-mail: nam1611@hanmail.net [Department of Cultural Heritage Conservation Science, Kongju National University, Gongju, 314-701 (Korea, Republic of); Lee, Jongmyoung [Laser Engineering Group, IMT Co. Ltd, Gyeonggi (Korea, Republic of)

2013-11-01

As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

Degradation measurement of bronzes, a recent application of the TLA techniques in the field of cultural heritage

International Nuclear Information System (INIS)

Danesi, P.R.; Laguzzi, G.; Luvidi, L

2001-01-01

The thin layer technique is normally applied in wear and corrosion monitoring of mechanical and plant components. A recent applications refers to the field of Cultural Heritage. In particular thought national and international research programmes TLA is used as a sensitivity toll in determining the properties towards corrosion of new bronze alloys to be used for artistic purposes, as in manufacturing of outdoor artworks. One activated and exposed to natural or artificial corrosive environments the bronze surface is treated with pick ling solutions to remove the corrosion products, The corresponding thickness loss is determined by the relevant γ-activity loss. The method sensitivity allows of the thickness loss evaluation in the order micrometers of lower. Besides comparative analyses of the behaviour of different bronze alloys, this method is also applied in determining the effectiveness of corrosion inhibitor or protective films, normally used on outdoor bronze sculptures. The metal activation is carried out by using a cyclotron accelerated proton beam (11.5 MeV) which products on the bronze surface and along a defined depth γemitting radionuclide 65 Zn (t 1/2 = 244 days). In the present paper, bronze corrosion results obtained in different environmental conditions as outdoor exposures and artificial weathering experiments are reported

Experiments and procedures for bottom-heating heat-transfer experiments through UO2 debris beds in sodium

International Nuclear Information System (INIS)

Sowa, E.S.; Pedersen, D.R.; Pavlik, J.; Purviance, R.

1982-01-01

Real materials experiments in heat transfer through beds of UO 2 in sodium have been performed at Argonne National Laboratory over a period of years. The most recent method utilizes the resistive heating in a sheet tungsten filament located at the base of the debris container. A schematic diagram of the apparatus is shown. The tungsten is clamped between two water cooled copper electrodes. The filament is a sheet of tungsten 0.15 mm thick, 5 cm wide and 18 cm long. Two 6.5 mm thick sheets of boron nitride sandwich the filament. The upper face of the upper boron nitride sheet is in intimate contact with the bottom of the debris container. Temperatures are measured at various levels in the bed as well as in the boron nitride plate. In addition, the sodium pool temperature is measured by the thermocouple. The heat transferral through the bed is measured by the temperature difference and mass flowrate in a NaK condenser located above the debris bed. The NaK inlet and outlet temperatures are recorded individually, as well as, differentially

Cloth cultures in prehistoric Europe: the Bronze Age evidence from Hallstatt

Directory of Open Access Journals (Sweden)

Susanna Harris

2009-09-01

Full Text Available Cloth Cultures in Prehistoric Europe is a Postdoctoral Fellowship project awarded to Susanna Harris by the British Academy. Its aim is to bring together and examine evidence for textiles and animal skins in prehistoric Europe from the Neolithic and Bronze Age. Several case studies are being examined as part of this project, including the Bronze Age Hallstatt salt mines. Here researchers working on the materials from Hallstatt look at some of the similarities and differences between the techniques applied to textiles and animal skins in their production and use in the mines.

Glycerol oxidehydration into acrolein and acrylic acid over W/V/Nb bronzes with hexagonal structure

Energy Technology Data Exchange (ETDEWEB)

Basile, F.; Cavani, F.; Chieregato, A. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali; CIRI Energia e Ambiente, Bologna (Italy); Concepcion, P.; Lopez Nieto, J.M.; Soriano, M.D. [Univ. Politecnica de Valencia (Spain). Inst. de Tecnologia Quimica; Liosi, G.; Trevisanut, C. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali

2012-07-01

This paper deals with an investigation of hexagonal W-V-Nb-O and W-V-Mo-O bronzes as catalysts for the one-pot oxidehydration of glycerol into acrylic acid. In a previous work, we reported a study on a bi-component bronze W-V-O that allowed us to obtain a 25% acrylic acid selectivity; in the current work, the incorporation of either Nb or Mo in a tri-component bronze structure allowed us to tune the acid and redox properties of the catalyst, so as to study their influence on the overall reaction scheme. (orig.)

Bronze railing from Mediana

Directory of Open Access Journals (Sweden)

Vasić Miloje R.

2003-01-01

Full Text Available The hoard containing components of bronze railing was discovered in trench 7 during excavations at Mediana in 2000. Railing consists of cancelli and herms with busts of deities between them. Railing was constructed in such a way that it was possible to disassemble and reassemble it. Three cancelli one fragmented semicancellus cast together with herm and herms, one with bust of Aesculapius and other with bust of Luna. It could be concluded that railing consisted of two segments with passage between them. Male deities were represented on the left segment of the railing and female deities on the right segment. Detailed analysis revealed that Aesculapius as well as Luna bear strong mark of classical Greek and Hellenistic art, which experienced some kind of renaissance in the time of Constantine I. It is very probable that we can recognize the portrait of Faustina, Constantine’s wife in the portrait of Luna. According to the historical events the railing could have been produced before 325 AD when Constantine definitively accepted Christianity at Council of Nicaea. It is difficult to say where the railing had been produced. It had been most probably brought to Mediana during the stay of emperor Julian in Niš in 361. The sculptures found in one room of the villa with peristyle had probably been brought at the same time. The apse of triclinium of this villa had most likely been arranged as small shrine with bronze railing at its entrance. The railing was buried in 378 after battle of Adrianople and invasion of Goths in diocese Dacia.

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

Study of wear mechanism of chopped fiber reinforced epoxy composite filled with graphite and bronze

Science.gov (United States)

Patil, Nitinchand; Prasad, Krishna

2018-04-01

The combined effect of graphite and sintered bronze with a short glass fiber reinforced epoxy composites was investigated in this work. A pin on disc wear test was carried out to study the wear behaviour and mechanism of the composites. The objective of this work is to develop an alternate friction resistance material for the application of sliding bearing. It was observed that the addition of sintered bronze improved mechanical and thermal stability of the composites as bronze has low contact resistance with graphite and has high thermal conductivity. It was observed from the test results that increased volume percentage of graphite and presence of bronze are play significant role in wear mechanism of the composites. It was observed from the scanning electronic microscopes (SEM) that the abrasive and adhesive wear mechanism was prominent in this study. It was also evident from the result that the frictional force remains stable irrespective of the applied normal load.

Haute Couture in the Bronze Age: A History of Minoan Female Costumes from Thera

DEFF Research Database (Denmark)

Nosch, Marie-Louise Bech

2008-01-01

Haute Couture in the Bronze Age from Thera is investigated via frescoes and with a historiographical approach on the reception of Minoan culture in contemporary Greek history......Haute Couture in the Bronze Age from Thera is investigated via frescoes and with a historiographical approach on the reception of Minoan culture in contemporary Greek history...

Development of quantitative atomic modeling for tungsten transport study using LHD plasma with tungsten pellet injection

Science.gov (United States)

Murakami, I.; Sakaue, H. A.; Suzuki, C.; Kato, D.; Goto, M.; Tamura, N.; Sudo, S.; Morita, S.

2015-09-01

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 plasmas of the large helical device (LHD) with tungsten pellet injection. We found that extreme ultraviolet (EUV) emission of W24+ to W33+ ions at 1.5-3.5 nm are sensitive to electron temperature and useful to examine the tungsten behavior in edge plasmas. We can reproduce measured EUV spectra at 1.5-3.5 nm by calculated spectra with the tungsten atomic model and obtain charge state distributions of tungsten ions in LHD plasmas at different temperatures around 1 keV. Our model is applied to calculate the unresolved transition array (UTA) seen at 4.5-7 nm tungsten spectra. We analyze the effect of configuration interaction on population kinetics related to the UTA structure in detail and find the importance of two-electron-one-photon transitions between 4p54dn+1- 4p64dn-14f. Radiation power rate of tungsten due to line emissions is also estimated with the model and is consistent with other models within factor 2.

75 FR 15764 - Culturally Significant Objects Imported for Exhibition Determinations: “Gods of Angkor: Bronzes...

Science.gov (United States)

2010-03-30

... Determinations: ``Gods of Angkor: Bronzes From the National Museum of Cambodia'' SUMMARY: Notice is hereby given... objects to be included in the exhibition ``Gods of Angkor: Bronzes from the National Museum of Cambodia,'' imported from abroad for temporary exhibition within the United States, are of cultural significance. The...

X-ray Photoelectron Spectroscopy as a tool to investigate silane-based coatings for the protection of outdoor bronze: The role of alloying elements

Science.gov (United States)

Masi, G.; Balbo, A.; Esvan, J.; Monticelli, C.; Avila, J.; Robbiola, L.; Bernardi, E.; Bignozzi, M. C.; Asensio, M. C.; Martini, C.; Chiavari, C.

2018-03-01

Application of a protective coating is the most widely used conservation treatment for outdoor bronzes (cast Cu-Sn-Zn-Pb-Sb alloys). However, improving coating protectiveness requires detailed knowledge of the coating/substrate chemical bonding. This is particularly the case for 3-mercapto-propyl-trimethoxy-silane (PropS-SH) applied on bronze, exhibiting a good protective behaviour in outdoor simulated conditions. The present work deals with X-Ray Photoelectron Spectroscopy (XPS) and Electron Microscopy (FEG-SEM + FIB (Focused Ion Beam)) characterization of a thin PropS-SH film on bronze. In particular, in order to better understand the influence of alloying elements on coating performance, PropS-SH was studied first on pure Cu and Sn substrates then on bronzes with increasing alloy additions: Cu8Sn as well as a quinary Cu-Sn-Zn-Pb-Sb bronze. Moreover, considering the real application of this coating on historical bronze substrates, previously artificially aged ("patinated") bronze samples were prepared and a comparison between bare and "patinated" quinary bronzes was performed. In the case of coated quinary bronze, the free surface of samples was analysed by High Resolution Photoelectron Spectroscopy using Synchrotron Radiation (HR-SRPES) at ANTARES (Synchrotron SOLEIL), which offers a higher energy and lateral resolution. By compiling complementary spectroscopic and imaging information, a deeper insight into the interactions between the protective coating and the bronze substrate was achieved.

Production of multifilamentary Nb3Sn composites incorporating a high tin bronze

International Nuclear Information System (INIS)

Petrovich, A.; Zeithlin, B.A.; Walker, M.S.

1977-01-01

The economics and processing methods have been examined for the fabrication of multifilamentary Nb 3 Sn using a high tin bronze reactive matrix. Four conductor configurations utilizing the high tin bronze were compared with a conventional Cu-13 wt % Sn bronze. The most promising of these designs is potentially 40% lower in cost per ampere meter than the conventional composite. Large hydrostatic extrusion facilities, which are required for the high tin processing, are not presently available in this country but can be made by conversion of conventional presses. They exist in Europe. Experiments were conducted to investigate the applicability of hydrostatic extrusion, and billet components were successfully prepared using the hydrostatic extrusion technique. We have concluded that the economics, availability of facilities and initial fabrication results are favorable for this type of conductor and that the next stage in this program of scale up to extrusion and drawing of 2'' to 3'' diameter composite billets should be undertaken

Determination of concentrations of minor and micro elements in ancient bronze drums artifacts samples by KO-standardization method of neutron activation analysis

International Nuclear Information System (INIS)

Nguyen Tac Anh; Ho Manh Dung; Diep Dinh Hoa; Cao Dong Vu

2000-01-01

The study aims to get a lot information about manufacturers of ancient bronze artifacts and ancient civilization. By KO-standardization method of neutron activation analysis developed in the Nuclear Research Institute, the concentrations of Au, Ag, As, Zn, Sb, Sn elements in ancient bronze alloy samples of 99 bronze artifacts from many excavated archaeological sites at the provinces in Vietnam were determined with uncertainties about ±10%. These elemental concentrations have been utilized in a statistical analysis procedure in order to determine similarities and correlation between the various samples. Th abnormal high of concentrations of noble metals as Au, Ag in ancient bronze indicates that the ancient metallurgists had been interested in role of these metals on sound quality of bronze artifacts. Especially, the concentrations of As in many samples are very high even at about 10%. This gives an evidence that in ancient time the humankind could use bronze As alloy in order to improve quality when they had produced bronze artifacts. (author)

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.

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

International Nuclear Information System (INIS)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H.

1992-01-01

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)

Learners’ Mistakes or Professional Error – the Nordic Bronze Age ornaments

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

Nordic Bronze Age ornaments are known for their rich decorations, often consisting of spiral bands used as part of a variety of other decorative elements. Even a cursory examination makes it clear that these ornaments vary greatly in terms of their quality. How can this variation be explained......? Is this the result of different workshops, levels of crafting skills or perhaps even the incorporation of novice metalworkers? As part of a study on craft organization in the Nordic Bronze Age, several metal workshops were analyzed in relation to the skill of the craftsmen and the amount of time involved...

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

Energy Technology Data Exchange (ETDEWEB)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H. [Academia Sinica, Taipei, TW (China). Inst. of Physics

1992-12-31

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).

Provenance study of a Bronze Age sword from Giurgiu

International Nuclear Information System (INIS)

Olariu, Agata; Badica, T.; Popescu, I. V.; Alexandrescu, E.

2000-01-01

This work is a compositional study of a bronze sword recently discovered near Giurgiu using the method of charged particles induced X ray emission (PIXE). The sword is of it Reutlingen type dated in the period Bronze Age D - Hallstatt A1, around 1200 B. C. The knowledge of its composition could give supplementary information about the provenance of this sword by comparing with other copper-based alloy objects from Bronze Age. To obtain the composition of the sword we have applied the method PIXE at the Tandem accelerator of IFIN-HH Magurele. We have extracted 3 samples from the body of the sword: one sample from the tip of the sword and 2 samples from the hilt. The samples have been flattened by a hammer and introduced in the irradiation chamber of the PIXE spectrometer. The targets have been irradiated by a current of protons of 3 MeV and about 5 nA from the linear accelerator Tandem of the department. The detection of the characteristic X ray emission have been done by a GeHP detector. The acquisition of the X ray spectra has been done online on a PC with a MCA interface Canberra. The detection system gave a 190 eV resolution at 5.9 keV. In the frame of the experimental conditions the following elements have been observed: As, Co, Cr, Cu, Fe, Ni, Pb, Sn and Zn. In the table we present the results of the PIXE analysis of the Bronze Age sword from Giurgiu. The instrumentation errors have been less than 15%. The values of the elemental concentrations have been normalized to 100%. In order to have a comparative study of composition we considered also the composition of 7 swords of the same type and from the same period from regions from the south of Danube in Bulgaria, and 6 copper-based alloy objects from Spalnaca deposit, in Transylvania, dated also Bronze Age. The sword from Giurgiu has a composition closer to the Bulgarian swords for the elements: As, Co, Cu, Ni, Sn. The ratios Sn/Cu versus As/Cu for the sword from Giurgiu, Spalnaca-Transylvania objects and

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

International Nuclear Information System (INIS)

Murakami, I.; Sakaue, H.A.; Suzuki, C.; Kato, D.; Goto, M.; Tamura, N.; Sudo, S.; Morita, S.

2014-10-01

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 W 24+ to W 33+ 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 W 44+ ion, the tungsten concentration is determined to be n(W 44+ )/n e = 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)

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.)

Early Bronze Age Houses in Upper Mesopotamia: Evidence of Dwellings or Private Enterprises?

OpenAIRE

Mas, Juliette

2014-01-01

This paper deals with the research I carried out on domestic architecture and private economy during Early Bronze Age in Upper-Mesopotamia. Archaeological records, as well as textual evidence, has been used to try to define private households activities and their relationships with official institutions. Households were the main source of production, distribution and consumption during the Early Bronze Age. As it seems that these private economic entities produced goods and crafts in their ow...

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 ...

Toughness enhancement of tungsten reinforced with short tungsten fibres

Energy Technology Data Exchange (ETDEWEB)

Jiang, Y. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhang, L.H. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Fang, Q.F., E-mail: qffang@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Zhang, T.; Wang, X.P.; Hao, T.; Liu, C.S. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2017-04-06

The feasibility and toughening efficiency of the short tungsten fibre reinforcement on tungsten were investigated in W{sub f}/W composites fabricated by powder metallurgy method of spark plasma sintering. Fibres in the composites presented a Z-free laminar structure. Partial recrystallization of fibre grains occurred but fibre crack or damage was not detected. Fracture energy of W{sub f}/W composites was estimated in tensile tests, and the results indicated great toughness improvement over pure tungsten in virtue of frictional pullout and plastic deformation of fibres, and matrix-fibres interfacial debonding since 873 K. The specimen with mass fraction of 10% and fibre diameter of 100 µm exhibits the largest elongation of 9±1.1% and the highest ultimate strength of 482±13 MPa at 873 K.

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N.

2018-01-01

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan

2018-02-12

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Process for recovering tungsten from alkaline leaching solution of tungsten ores

International Nuclear Information System (INIS)

Onozaki, S.; Nemoto, S.; Hazeyama, T.

1976-01-01

This invention relates to a process for recovering tungsten from an alkaline leaching solution of tungsten ores. This invention comprises adjusting the pH of an alkaline leaching solution which is obtained by lixiviating ore containing tungsten with an alkaline solution to 7--8 with acid to oxidize molybdic acid ions in the solution, adding a sulfide donor, then precipitating molybdenum sulfide compounds by adjusting the pH value of the solution to 2--3. Tungstic acid ions are recovered as calcium tungstate by the addition of a calcium ion donor after the molybdenum sulfide compounds are separated

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

International Nuclear Information System (INIS)

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

2016-01-01

Graphical abstract: - Highlights: • Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb). • Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer. • SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing. • Selective dissolution of Cu and Zn in the craters induces Sn species enrichment. • The main species in the craters are related to hydroxi-oxide compounds. - Abstract: 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 (<200 nm) using high energy and lateral resolution synchrotron radiation photoemission (HR-SRPES) of core levels and valence band after conventional characterisation of the samples by Glow Discharge optical Emission Spectroscopy (GD-OES) and conventional X-ray photoelectron spectroscopy (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

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

Energy Technology Data Exchange (ETDEWEB)

Masi, G., E-mail: giulia.masi5@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Chiavari, C., E-mail: cristina.chiavari@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); C.I.R.I. (Centro Interdipartimentale Ricerca Industriale) Meccanica Avanzata e Materiali, Università di Bologna, Bologna, via Terracini 28, 40131 Bologna (Italy); Avila, J., E-mail: jose.avila@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Esvan, J., E-mail: jerome.esvan@ensiacet.fr [Centre Interuniversitaire de Recherche et d’Ingénierie des Matériaux, Université de Toulouse, 4 allée Emile Monso, 31030 Toulouse (France); Raffo, S., E-mail: simona.raffo2@unibo.it [Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, viale Risorgimento 4, 40136 Bologna (Italy); Bignozzi, M.C., E-mail: maria.bignozzi@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Asensio, M.C., E-mail: maria-carmen.asensio@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Robbiola, L., E-mail: robbiola@univ-tlse2.fr [TRACES Lab (CNRS UMR5608), Université Toulouse Jean-Jaurès, 5, allées Antonio-Machado, 31058 Toulouse (France); and others

2016-03-15

Graphical abstract: - Highlights: • Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb). • Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer. • SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing. • Selective dissolution of Cu and Zn in the craters induces Sn species enrichment. • The main species in the craters are related to hydroxi-oxide compounds. - Abstract: 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 (<200 nm) using high energy and lateral resolution synchrotron radiation photoemission (HR-SRPES) of core levels and valence band after conventional characterisation of the samples by Glow Discharge optical Emission Spectroscopy (GD-OES) and conventional X-ray photoelectron spectroscopy (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

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.

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

International Nuclear Information System (INIS)

Hai-Yan, Wang; Jian-Hua, Liu; Gui-Rong, Peng; Yan, Chen; Yu-Wen, Liu; Fei, Li; Wen-Kui, Wang

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

Tungsten Filament Fire

Science.gov (United States)

Ruiz, Michael J.; Perkins, James

2016-01-01

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…

Bioarchaeology of adaptation to a marginal environment in bronze age Western China.

Science.gov (United States)

Berger, Elizabeth; Wang, Hui

2017-07-08

This study examines human adaptation to the 4000 BP climate change event, which is said to have increased the marginality of Inner Asian environments. We propose to define "marginal" environments not in relation to a specific economic activity (e.g., agriculture), but in relation to whether humans living there are physiologically stressed. Three sites in the Hexi Corridor of Gansu were studied, one from the early and two from the late Bronze Age (N = 125). The study includes three indicators of physiological stress: linear enamel hypoplasias (LEH); tibial periosteal lesions; and fertility. The early and late Bronze Age groups were compared to examine whether human physiological stress increased. The percent of individuals with LEH declined dramatically, indicating fewer growth disruptions. Tibial periosteal reactions also changed, from mostly active to mostly healing at the time of death, indicating that frailty declined. Fertility, which is sensitive to changes in population health and resource availability, did not change significantly. Counter to the dominant narrative of environmental deterioration and subsistence system collapse, the Bronze Age residents of the Hexi Corridor show no skeletal evidence that they suffered from resource shortages or struggled to adapt in the fluctuating climate that pertained after the 4000 BP climate event. In fact, this study found that people suffered from less frailty and fewer growth disruptions after the unstable climate had persisted for some time. Therefore, in human biological terms, the Hexi Corridor did not become more marginal for human habitation during the Bronze Age. © 2017 Wiley Periodicals, Inc.

Tungsten behaviour under anodic polarization

International Nuclear Information System (INIS)

Vas'ko, A.T.; Patsyuk, F.N.

1980-01-01

Electrochemical investigations have been carried out to identify the state of elements of the tungsten galvanic coating. Active zones on anode polarization curves in the hydrogen region of galvanic tungsten are established. The difference in the behaviour of monocrystal and galvanic tungsten electrodes is shown to be connected with the oxidation of hydrogen in the galvanic sediment

Helium bubble bursting in tungsten

International Nuclear Information System (INIS)

Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.

2013-01-01

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

Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean hills

International Nuclear Information System (INIS)

Friedman, E. S.; Brody, A. J.; Young, M. L.; Almer, J. D.; Serge, C. U.; Mini, S. M.

2008-01-01

Seven bronze bangles from Tell en-Nasbeh, northern Judah, were investigated to understand the phase composition and manufacturing process of the artifacts, and possibly suggest a provenance for their origin. Synchrotron x-ray radiation diffraction (XRD) and fluorescence (XRF) were used in the analysis to avoid any destructive sampling and at the same time penetrate through the surface into the core metal. These techniques enabled us to determine that the bangles were not just tin bronze, but leaded tin bronze. Based on excavation reports, it is unlikely that the metal objects were manufactured locally at Tell en-Nasbeh; rather, preliminary XRD and XRF data point towards the neighboring region of Edom as their origin. Despite their political enmity during the Iron Age II, the data suggest that Judahite social demands for bronze may have fostered a strong economic relationship between these two polities

Elemental analysis of bronze artifacts by muonic X-ray spectroscopy

International Nuclear Information System (INIS)

Ninomiya, Kazuhiko; Shinohara, Atsushi; Kubo, Michael K.; Strasser, Patrick; Nagatomo, Takashi; Kawamura, Naritoshi; Shimomura, Koichiro; Miyake, Yasuhiro; Kobayashi, Yoshio; Ishida, Katsuhiko; Higemoto, Wataru; Suzuki, Takao; Saito, Tsutomu

2015-01-01

A quantitative and multi-elemental analysis method for bulk samples based on muonic X-ray spectroscopy was applied to bronze artifacts (Tempo-Tsuho coins and a Seiun-kyo mirror). This method is based on the measurement of the characteristic high-energy muonic X-rays emitted in a sample after muon irradiation. The elemental compositions of these bronze artifacts were determined from muonic X-ray intensities in a non-destructive manner, using the relation between the muonic X-ray intensity and the elemental composition of the Cu–Sn–Pb alloy system. The analyzed values agreed well with those determined by X-ray fluorescence spectroscopy. We also estimated the detection limit of this method in the present experimental setup as 0.81 wt% of the background signal of the muonic X-ray spectra. (author)

Breakthrough of the Nordic Bronze Age: Transcultural warriorhood and a Carpathian crossroad in the 16th century BC

DEFF Research Database (Denmark)

Vandkilde, Helle

2014-01-01

The breakthrough of the Nordic Bronze Age (NBA) c. 1600 bc as a koiné within Bronze Age Europe can be historically linked to the Carpathian Basin. Nordic distinctiveness entailed an entanglement of cosmology and warriorhood, albeit represented through different media in the hotspot zone (bronze) ...... momentous creativity that drew upon Carpathian originals, contacts and a pool of Carpathian ideas, but ultimately drawing on emergent Mycenaean hegemonies in the Aegean. This provided the incentive for a cosmology-rooted resource from which the NBA could take its starting point....

Scanning tunneling microscopy measurements of the spin Hall effect in tungsten films by using iron-coated tungsten tips

Science.gov (United States)

Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

2018-05-01

Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.

Application of microjet in heat treatment of aluminium bronzes

Directory of Open Access Journals (Sweden)

Z. Górny

2011-04-01

Full Text Available Mechanical properties of a CuAl10Fe4Ni4 bronze subjected to solution heat treatment and toughening were examined. In solution heattreatment, a microjet was used to raise the cooling rate. A slight increase of mechanical properties was observed.

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.

Non-invasive chemical and phase analysis of Roman bronze artefacts from Thamusida (Morocco)

Energy Technology Data Exchange (ETDEWEB)

Gliozzo, Elisabetta, E-mail: gliozzo@unisi.i [Dipartimento di Scienze della Terra, Universita di Siena, via Laterina 8, 53100 Siena (Italy); Arletti, Rossella, E-mail: rarletti@unimore.i [Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia, Largo S. Eufemia 19, 41100 Modena (Italy); Cartechini, Laura, E-mail: laura@thch.unipg.i [Istituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM), c/o Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Imberti, Silvia, E-mail: Silvia.Imberti@stfc.ac.u [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX (United Kingdom); Kockelmann, Winfried A., E-mail: Winfried.Kockelmann@stfc.ac.u [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX (United Kingdom); Memmi, Isabella, E-mail: memmi@unisi.i [Dipartimento di Scienze della Terra, Universita di Siena, via Laterina 8, 53100 Siena (Italy); Rinaldi, Romano, E-mail: rrinaldi@unipg.i [Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Tykot, Robert H., E-mail: rtykot@cas.usf.ed [Department of Anthropology, University of South Florida, Tampa, FL 33620 (United States)

2010-12-15

A repertory of Roman military bronze equipment (1st- 3rd century AD) found at the archaeological site of Thamusida (Rabat, Morocco) was analysed by non-destructive X-ray fluorescence and time of flight neutron diffraction (TOF-ND). Most objects are made of leaded alloys, where copper is combined with tin and/or zinc and, in six cases, to arsenic as well. A mixed technology was employed, making a limited use of 'pure' semi-finished materials if compared with the large utilization of recycled materials (brass and bronze).

Surface characterization of a corroded bronze-leaded alloy in a salt spray cabinet

International Nuclear Information System (INIS)

Cura D'Ars de Figueiredo Junior, Joao; Freitas Cunha Lins, Vanessa de; Bellis, Vito Modesto de

2007-01-01

The corrosion products of a TM 23 bronze-leaded alloy (Cu 72%, Pb 15%, Zn 8% and Sn 5%) were obtained in a salt spray cabinet after exposition during 120 h and 1000 h. The products obtained were studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The major products of bronze-leaded corrosion were oxides and basic salts of Cu, CuCl 2 .3Cu(OH) 2 , and Pb, Pb(OH)Cl. The results can be attributed to a kinetic control of the corrosion reactions

Scanning tunneling microscopy measurements of the spin Hall effect in tungsten films by using iron-coated tungsten tips

Directory of Open Access Journals (Sweden)

Ting Xie

2018-05-01

Full Text Available Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.

14C dating of the Early to Late Bronze Age stratigraphic sequence of Aegina Kolonna, Greece

International Nuclear Information System (INIS)

Wild, E.M.; Gauss, W.; Forstenpointner, G.; Lindblom, M.; Smetana, R.; Steier, P.; Thanheiser, U.; Weninger, F.

2010-01-01

Aegina Kolonna, located in the center of the Saronic Gulf in the Aegean Mediterranean (Greece), is one of the major archaeological sites of the Aegean Bronze Age with a continuous stratigraphic settlement sequence from the Late Neolithic to the Late Bronze Age. Due to its position next to the maritime cross roads between central mainland Greece, the northeast Peloponnese, the Cyclades and Crete, the island played an important role in the trade between these regions. In the course of new excavations, which focused on the exploration of the Early, Middle and Late Bronze Age at Kolonna, several short lived samples from different settlement phases have been 14 C-dated with the AMS method at the VERA laboratory. Bayesian sequencing of the 14 C data according to the stratigraphic position of the samples in the profile was performed to enable estimates of the transition time between the cultural phases. The Aegina Kolonna 14 C sequence is one of the longest existing so far for the Aegean Bronze Age, and therefore of major importance for the absolute Bronze Age chronology in this region. Preliminary results indicate that the Middle Helladic period seems to have started earlier and lasted longer than traditionally assumed. Further, at the present stage of our investigation we can give also a very tentative time frame for the Santorini volcanic eruption which seems to be in agreement with the science derived VDL date.

Building the Bronze Age : Architectural and social change on the Greek mainland during Early Helladic III, Middle Helladic and Late Helladic I

NARCIS (Netherlands)

Wiersma, Corien

2014-01-01

Communities living on the Greek Mainland during the end of the Early Bronze Age (EBA. ca. 2200-2000 BC) and the earlier Middle Bronze Age (MBA, ca. 2000-1800 BC) were thought to be relatively simple and egalitarian, while during the later MBA and early Late Bronze Age (LBA, ca. 1700-1600 BC),

Examination of Ife Bronze Casting Culture and Its Decline in ...

African Journals Online (AJOL)

DrNneka

civilization and culture, education, science and technology. ... to set up bronze casting industry to promote the commercial culture in the history of. Ife. ..... the development of science and technological advancement, while to others; it is the.

Reduction of blue tungsten oxide

International Nuclear Information System (INIS)

Wilken, T.; Wert, C.; Woodhouse, J.; Morcom, W.

1975-01-01

A significant portion of commercial tungsten is produced by hydrogen reduction of oxides. Although several modes of reduction are possible, hydrogen reduction is used where high purity tungsten is required and where the addition of other elements or compounds is desired for modification of the metal, as is done for filaments in the lamp industry. Although several investigations of the reduction of oxides have been reported (1 to 5), few principles have been developed which can aid in assessment of current commercial practice. The reduction process was examined under conditions approximating commercial practice. The specific objectives were to determine the effects of dopants, of water vapor in the reducing atmosphere, and of reduction temperature upon: (1) the rate of the reaction by which blue tungsten oxide is reduced to tungsten metal, (2) the intermediate oxides associated with reduction, and (3) the morphology of the resulting tungsten powder

Micro-powder injection moulding of tungsten

International Nuclear Information System (INIS)

Zeep, B.

2007-12-01

For He-cooled Divertors as integral components of future fusion power plants, about 300000 complex shaped tungsten components are to be fabricated. Tungsten is the favoured material because of its excellent properties (high melting point, high hardness, high sputtering resistance, high thermal conductivity). However, the material's properties cause major problems for large scale production of complex shaped components. Due to the resistance of tungsten to mechanical machining, new fabrication technologies have to be developed. Powder injection moulding as a well established shaping technology for a large scale production of complex or even micro structured parts might be a suitable method to produce tungsten components for fusion applications but is not yet commercially available. The present thesis is dealing with the development of a powder injection moulding process for micro structured tungsten components. To develop a suitable feedstock, the powder particle properties, the binder formulation and the solid load were optimised. To meet the requirements for a replication of micro patterned cavities, a special target was to define the smallest powder particle size applicable for micro-powder injection moulding. To investigate the injection moulding performance of the developed feedstocks, experiments were successfully carried out applying diverse cavities with structural details in micro dimension. For debinding of the green bodies, a combination of solvent debinding and thermal debinding has been adopted for injection moulded tungsten components. To develop a suitable debinding strategy, a variation of the solvent debinding time, the heating rate and the binder formulation was performed. For investigating the thermal consolidation behaviour of tungsten components, sinter experiments were carried out applying tungsten powders suitable for micro-powder injection moulding. First mechanical tests of the sintered samples showed promising material properties such as a

Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous ...

Indian Academy of Sciences (India)

Administrator

These compounds act through the formation of a protective film on the surface of the ... Bronze; inhibitors; quinoxalin compounds; chloride solution; electrochemical studies. 1. ... elements such as aluminum, nickel and iron offer a good ... cations such as pump casting, valves and heat exchanger. ..... to investigate this layer.

Impact of residual by-products from tungsten film deposition on process integration due to nonuniformity of the tungsten film

CERN Document Server

Sidhwa, A; Gandy, T; Melosky, S; Brown, W; Ang, S; Naseem, H; Ulrich, R

2002-01-01

The effects of residual by products from a tungsten film deposition process and their impact on process integration due to the nonuniformity of the tungsten film were investigated in this work. The tungsten film deposition process involves three steps: nucleation, stabilization, and tungsten bulk fill. Six experiments were conducted in search for a solution to the problem. The resulting data suggest that excess nitrogen left in the chamber following the tungsten nucleation step, along with residual by products, causes a shift in the tungsten film uniformity during the tungsten bulk fill process. Data reveal that, due to the residual by products, an abnormal grain growth occurs causing a variation in the tungsten thickness across the wafer during the bulk fill step. Although several possible solutions were revealed by the experiments, potential integration problems limited the acceptable solutions to one. The solution chosen was the introduction of a 10 s pumpdown immediately following the nucleation step. Thi...

Characterization and performances of cobalt-tungsten and molybdenum-tungsten carbides as anode catalyst for PEFC

International Nuclear Information System (INIS)

Izhar, Shamsul; Yoshida, Michiko; Nagai, Masatoshi

2009-01-01

The preparation of carbon-supported cobalt-tungsten and molybdenum-tungsten carbides and their activity as an anode catalyst for a polymer electrolyte fuel cell were investigated. The electrocatalytic activity for the hydrogen oxidation reaction over the catalysts was evaluated using a single-stack fuel cell and a rotating disk electrode. The characterization of the catalysts was performed by XRD, temperature-programmed carburization, temperature-programmed reduction and X-ray photoelectron spectroscopy. The maximum power densities of the 30 wt% 873 K-carburized cobalt-tungsten and molybdenum-tungsten mixed with Ketjen carbon (cobalt-tungsten carbide (CoWC)/Ketjen black (KB) and molybdenum-tungsten carbide (MoWC)/KB) were 15.7 and 12.0 mW cm -2 , respectively, which were 14 and 11%, compared to the in-house membrane electrode assembly (MEA) prepared from a 20 wt% Pt/C catalyst. The CoWC/KB catalyst exhibited the highest maximum power density compared to the MoWC/KB and WC/KB catalysts. The 873 K-carburized CoW/KB catalyst formed the oxycarbided and/or carbided CoW that are responsible for the excellent hydrogen oxygen reaction

Manipulation of polar order in the “empty” tetragonal tungsten bronzes: Ba{sub 4-x}Sr{sub x}Dy{sub 0.67}□{sub 1.33}Nb{sub 10}O{sub 30}, x = 0, 0.25, 0.5, 1, 2, 3

Energy Technology Data Exchange (ETDEWEB)

Gardner, Jonathan; Morrison, Finlay D., E-mail: finlay.morrison@st-andrews.ac.uk [EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom)

2016-08-15

A series of “empty” tetragonal tungsten bronze (TTB) ferroelectrics, Ba{sub 4-x}Sr{sub x}Dy{sub 0.67}□{sub 1.33}Nb{sub 10}O{sub 30} (x = 0, 0.25, 0.5, 1, 2, 3; □ = vacancy), is reported. With increasing x the unit cell contracts in both the ab plane and c-axis; x ≤ 1 compounds are normal ferroelectrics (FE) with decreasing T{sub C} as x increases, while x ≥ 2 are relaxor ferroelectrics (RFE) with associated frequency dependent permittivity peaks and with similar T{sub m} and T{sub f} (Vogel-Fulcher freezing temperatures) values. This observation is rationalised by differing cation occupancies: for x ≤ 1, Sr{sup 2+} principally occupies the A2-site (co-occupied by Ba{sup 2+} with the A1-site occupied by Dy{sup 3+} and vacancies); for x ≥ 2 significant Sr A1-site occupation leads to the observed RFE characteristics. This FE to RFE crossover is consistent with a previously proposed TTB crystal chemical framework where both a decrease in average A-site size and concurrent increase in A1-site tolerance factor (t{sub A1}) favour destabilization of long range polar order and relaxor behaviour. The effect of increasing t{sub A1} as a result of Sr occupancy at the A1 site is dominant in the compounds reported here.

Casting Simulation of an Austrian Bronze Age Sword Hilt

Science.gov (United States)

Pola, Annalisa; Mödlinger, Marianne; Piccardo, Paolo; Montesano, Lorenzo

2015-07-01

Bronze Age swords with a metal hilt can be considered the peak of Bronze Age casting technologies. To reconstruct the casting techniques used more than 3000 years ago, a metal hilted sword of the Schalenknauf type from Lower Austria was studied with the aid of macroscopic analyses and simulation of mold filling and casting solidification. A three-dimensional model of the hilt was created based on optical scanner measurements performed on a hilt recently discovered during archaeological excavations. Three different configurations of the gating system were considered, two on the pommel disk and one on the knob, and the effect of its location on the formation of casting defects was investigated. Three-dimensional computed tomography was used to detect internal defects, such as gas and shrinkage porosity, which were then compared with those calculated by simulation. The best match between actual and predicted hilt quality demonstrated the location of the gating system, which turned out to be on the pommel disk.

Irradiation effects in tungsten-copper laminate composite

Energy Technology Data Exchange (ETDEWEB)

Garrison, L.M., E-mail: garrisonlm@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Katoh, Y. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Snead, L.L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Byun, T.S. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Reiser, J.; Rieth, M. [Karlsruhe Institute of Technology, Karlsruhe (Germany)

2016-12-01

Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410–780 °C and fast neutron fluences of 0.02–9.0 × 10{sup 25} n/m{sup 2}, E > 0.1 MeV, 0.0039–1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile. - Highlights: • Fusion reactors need a tough, ductile tungsten plasma-facing material. • The unirradiated tungsten-copper laminate is more ductile than tungsten alone. • After neutron irradiation, the composite has significantly less ductility. • The tungsten behavior appears to dominate the overall composite behavior.

Chisels in the italian Bronze Age: technological and typological aspects

Directory of Open Access Journals (Sweden)

Speciale, Claudia

2010-12-01

Full Text Available Bronze chisels are tools used “à percussion posée”; this means they need a minimum length and some functional parts (tang, body, blade; they could have a handle of perishable material and they were used with a hammer to work wood, bronze and other materials. Chisels can be classified following their functional parts; the first element is the shape (rod or socketed chisel; the second one is body section; the third one is tang section. Chronology and distribution of every type were identified to obtain a general view of this class of tools during the Italian Bronze Age.

Los cinceles de bronce son herramientas que se utilizan en percusión apoyada (à percussion posée, por consiguiente, necesitan una longitud mínima y algunas partes funcionales (empuñadura, cuerpo, hoja; podrían tener un mango de material perecedero. Se utilizan con un martillo en el labrado de la madera, del bronce y de otros materiales. Los cinceles se pueden clasificar de acuerdo con los siguientes elementos funcionales: el primero es la forma (cincel de varilla o de cubo; el segundo es la sección del cuerpo; el tercero es la sección de la empuñadura. La cronología y la distribución de cada tipo se identificaron para obtener una visión general de esta clase de instrumentos durante la Edad del Bronce en Italia.

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.

48 CFR 252.216-7000 - Economic price adjustment-basic steel, aluminum, brass, bronze, or copper mill products.

Science.gov (United States)

2010-10-01

...-basic steel, aluminum, brass, bronze, or copper mill products. 252.216-7000 Section 252.216-7000 Federal... adjustment—basic steel, aluminum, brass, bronze, or copper mill products. As prescribed in 216.203-4-70(a... Mill Products (JUL 1997) (a) Definitions. As used in this clause— Established price means a price which...

Effect of bronze on the compression of Nb3Sn in multifilamentary conductors

International Nuclear Information System (INIS)

Rupp, G.

1978-01-01

Nb 3 Sn in multifilamentary conductors is subject to compressive strain as a result of the relatively small thermal contraction of the filaments as compared to bronze. The critical current Isub(c) is consequently degraded. The critical current increases, when an external tensile stress is applied, and passes through a maximum. The ratio of the maximum critical current to the initial critical current increases with the flux density and reaches a value of two at a flux density of 16 T for technical conductors. The strain epsilonsub(m), at which Isub(c) maximum is reached, lies between 0.4% and 0.7% for the conductors investigated and depends on the material parameters. For a constant ratio of bronze to filament cross section this strain epsilonsub(m) is reduced as the Nb 3 Sn layer thickness is increased and can be determined approximately by a graphical method from the stress-strain diagram. Epsilonsub(m) is to a large extent dependent on the metallurgical properties of bronze, which vary to a considerable extent depending upon the heat treatment. (author)

An investigation of tungsten by neutron activation techniques

International Nuclear Information System (INIS)

Svetsreni, R.

1978-01-01

This investigation used neutron from Plutonium-Beryllium source (5 curie) to analyse the amount of tungsten in tungsten oxide which was extracted from tungsten ores, slag and tungsten alloy of tungsten iron and carbon. The technique of neutron activation analysis with NaI(Tl) gamma detector 3'' x 3'' and 1024 multichannel analyzer. The dilution technique was used by mixing Fe 2 O 3 or pure sand into the sample before irradiation. In this study self shielding effect in the analysis of tungsten was solved and the detection limit of the tungsten in the sample was about 0.5%

One-Step Synthesis of Titanium Oxyhydroxy-Fluoride Rods and Research on the Electrochemical Performance for Lithium-ion Batteries and Sodium-ion Batteries.

Science.gov (United States)

Li, Biao; Gao, Zhan; Wang, Dake; Hao, Qiaoyan; Wang, Yan; Wang, Yongkun; Tang, Kaibin

2015-12-01

Titanium oxyhydroxy-fluoride, TiO0.9(OH)0.9F1.2 · 0.59H2O rods with a hexagonal tungsten bronze (HTB) structure, was synthesized via a facile one-step solvothermal method. The structure, morphology, and component of the products were characterized by X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatograph, energy-dispersive X-ray (EDX) analyses, and so on. Different rod morphologies which ranged from nanoscale to submicron scale were simply obtained by adjusting reaction conditions. With one-dimension channels for Li/Na intercalation/de-intercalation, the electrochemical performance of titanium oxyhydroxy-fluoride for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was also studied. Electrochemical tests revealed that, for LIBs, titanium oxyhydroxy-fluoride exhibited a stabilized reversible capacity of 200 mAh g(-1) at 25 mA g(-1) up to 120 cycles in the electrode potential range of 3.0-1.2 V and 140 mAh g(-1) at 250 mA g(-1) up to 500 cycles, especially; for SIBs, a high capacity of 100 mAh g(-1) was maintained at 25 mA g(-1) after 115 cycles in the potential range of 2.9-0.5 V.

Hydrogen permeation properties of plasma-sprayed tungsten

International Nuclear Information System (INIS)

Anderl, R.A.; Pawelko, R.J.; Hankins, M.R.; Longhurst, G.R.; Neiser, R.A.

1994-01-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D + 3 ion beam with fluxes of similar 6.5x10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

Hydrogen permeation properties of plasma-sprayed tungsten

Energy Technology Data Exchange (ETDEWEB)

Anderl, R.A. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Pawelko, R.J. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Hankins, M.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Longhurst, G.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Neiser, R.A. (Sandia National Laboratories, Albuquerque, NM 87185 (United States))

1994-09-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D[sup +][sub 3] ion beam with fluxes of similar 6.5x10[sup 19] D/m[sup 2] s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

Kinetics of low pressure chemical vapor deposition of tungsten silicide from dichlorocilane reduction of tungsten hexafluoride

International Nuclear Information System (INIS)

Srinivas, D.; Raupp, G.B.; Hillman, J.

1990-01-01

The authors report on experiments to determine the intrinsic surface reaction rate dependences and film properties' dependence on local reactant partial pressures and wafer temperature in low pressure chemical vapor deposition (LPCVD) of tungsten silicide from dichlorosilane reduction of tungsten hexafluoride. Films were deposited in a commercial-scale Spectrum CVD cold wall single wafer reactor under near differential, gradientless conditions. Over the range of process conditions investigated, deposition rate was found to be first order in dichlorosillane and negative second order in tungsten hexafluoride partial pressure. The apparent activation energy in the surface reaction limited regime was found to be 70-120 kcal/mol. The silicon to tungsten ratio of as deposited silicide films ranged from 1.1 to 2.4, and increased with increasing temperature and dichlorosillane partial pressure, and decreased with increasing tungsten hexafluoride pressure. These results suggest that the apparent silicide deposition rate and composition are controlled by the relative rates of at least two competing reactions which deposit stoichiometric tungsten silicides and/or silicon

MEGAPIE analytical support task : characterization of lead-bismuth eutectic and sodium-cooled tungsten target materials for accelerator driven systems

International Nuclear Information System (INIS)

Gohar, Y.

2002-01-01

Lead-Bismuth Eutectic and Tungsten are under consideration as target materials with high-energy protons for generating neutrons to drive actinide and fission product transmuters. A detailed characterization has been performed to study the performance of these target materials as a function of the main variables and the design selections. The characterization includes the neutron yield, the spatial energy deposition, the neutron spectrum, the beam window performance, and the target buffer impact on the target performance. The characterization has also considered high-energy deuteron particles to study the impact on the target neutronic performance. The obtained results quantify the performance of the Lead-Bismuth Eutectic and Tungsten target materials as a function of the target variables and design selections

Foraging behaviour in tadpoles of the bronze frog Rana temporalis ...

Indian Academy of Sciences (India)

Unknown

The ability of bronze frog Rana temporalis tadpoles (pure or mixed parental lines) to ... less of whether they are siblings or non-siblings in a group, which correlates well with ..... Sutherland W J and Parker G A 1992 The relationship between.

Hydrogen retention properties of polycrystalline tungsten and helium irradiated tungsten

International Nuclear Information System (INIS)

Hino, T.; Koyama, K.; Yamauchi, Y.; Hirohata, Y.

1998-01-01

The hydrogen retention properties of a polycrystalline tungsten and tungsten irradiated by helium ions with an energy of 5 keV were examined by using an ECR ion irradiation apparatus and a technique of thermal desorption spectroscopy, TDS. The polycrystalline tungsten was irradiated at RT with energetic hydrogen ions, with a flux of 10 15 H cm -2 and an energy of 1.7 keV up to a fluence of 5 x 10 18 H cm -2 . Subsequently, the amount of retained hydrogen was measured by TDS. The heating temperature was increased from RT to 1000 C, and the heating rate was 50 C min -1 . Below 1000 C, two distinct hydrogen desorption peaks were observed at 200 C and 400 C. The retained amount of hydrogen was observed to be five times smaller than that of graphite, but the concentration in the implantation layer was comparable with that of graphite. Also, the polycrystalline tungsten was irradiated with 5 keV helium ions up to a fluence of 1.4 x 10 18 He cm -2 , and then re-irradiated with 1.7 keV hydrogen ions. The amount of retained hydrogen in this later experiment was close to the value in the case without prior helium ion irradiation. However, the amount of hydrogen which desorbed around the low temperature peak, 200 C, was largely enhanced. The desorption amount at 200 C saturated for the helium fluence of more than 5 x 10 17 He cm -2 . The present data shows that the trapping state of hydrogen is largely changed by the helium ion irradiation. Additionally, 5 keV helium ion irradiation was conducted on a sample pre-implanted with hydrogen ions to simulate a helium ion impact desorption of hydrogen retained in tungsten. The amount of the hydrogen was reduced as much as 50%. (orig.)

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

International Nuclear Information System (INIS)

Šatović, D.; Desnica, V.; Fazinić, S.

2013-01-01

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

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.

Fractographic peculiarities of cermet tungsten fracture

International Nuclear Information System (INIS)

Stepanenko, V.A.; Babak, A.V.; Uskov, E.I.

1982-01-01

Effect of test temperature on fracture peculiarities of cermets tungsten with initial cellular structure of deformation is shown. Tungsten crack resistance increases at temperatures to Tsub(x) (ductile-brittle transition temperature) and decreases at temperatures above Tsub(x). The degree of ceramics tungsten plasticity realization depends on its crack resistance

Community Geothermal Technology Program: Silica bronze project. Final report

Energy Technology Data Exchange (ETDEWEB)

Bianchini, H.

1989-10-01

Objective was to incorporate waste silica from the HGP-A geothermal well in Pohoiki with other refractory materials for investment casting of bronze sculpture. The best composition for casting is about 50% silica, 25% red cinders, and 25% brick dust; remaining ingredient is a binder, such as plaster and water.

Tungsten wire and tubing joined by nickel brazing

Science.gov (United States)

1965-01-01

Thin tungsten wire and tungsten tubing are brazed together using a contacting coil of nickel wire heated to its melting point in an inert-gas atmosphere. This method is also effective for brazing tungsten to tungsten-rhenium parts.

Friction Stir Processing Parameters and Property Distributions in Cast Nickel Aluminum Bronze

National Research Council Canada - National Science Library

Rosemark, Brian P

2006-01-01

Cast nickel-aluminum bronze (NAB) alloy is specified for many marine applications, including ship propellers, due to its excellent corrosion-resistance combined with acceptable mechanical properties...

The inhibition effect and mechanism of L-cysteine on the corrosion of bronze covered with a CuCl patina

International Nuclear Information System (INIS)

Wang, Tianran; Wang, Julin; Wu, Yuqing

2015-01-01

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

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.

Micro creep mechanisms of tungsten

International Nuclear Information System (INIS)

Levoy, R.; Hugon, I.; Burlet, H.; Baillin, X.; Guetaz, L.

2000-01-01

Due to its high melting point (3410 deg C), tungsten offers good mechanical properties at elevated temperatures for several applications in non-oxidizing environment. The creep behavior of tungsten is well known between 1200 and 2500 deg C and 10 -3 to 10 -1 strain. However, in some applications when dimensional stability of components is required, these strains are excessive and it is necessary to know the creep behavior of the material for micro-strains (between 10 -4 and 10 -6 ). Methods and devices used to measure creep micro-strains are presented, and creep equations (Norton and Chaboche laws) were developed for wrought, annealed and recrystallized tungsten. The main results obtained on tungsten under low stresses are: stress exponent 1, symmetry of micro-strains in creep-tension and creep-compression, inverse creep (threshold stress), etc. TEM, SEM and EBSD studies allow interpretation of the micro-creep mechanism of tungsten under low stresses and low temperature (∼0.3 K) like the Harper-Dorn creep. In Harper-Dorn creep, micro-strains are associated with the density and the distribution of dislocations existing in the crystals before creep. At 975 deg C, the initial dislocation structure moves differently whether or not a stress is applied. To improve the micro-creep behavior of tungsten, a heat treatment is proposed to create the optimum dislocation structure. (authors)

Use your eyes - metallographic versus superficial traces of the crafting of Bronze Age ornaments

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

and superficial archaeological examinations can be used to understand prehistoric craft. Furthermore, it will show that with an intensive knowledge about previous scientific investigations the superficial traces preserved can reveal a great amount of information and could talk for themselves. Taking as an example...... the early and middle Bronze Age bronze ornaments from North Germany, superficial traces of the metal crafting process, visible with the naked eye, will be compared with metallographic images. The aim of this presentation is to give an overview over the crafting traces everybody could see (with a bit...

Determination of the elemental composition of copper and bronze objects by neutron activation analysis

International Nuclear Information System (INIS)

Hoelttae, P.; Rosenberg, R.J.

1986-01-01

A method for the elemental analysis of copper and bronze objects is described. Na, Co, Ni, Cu, Zn, As, Ag, Sn, Sb, W, Ir and Au are determined through instrumental neutron activation analysis. Mg, Al, V, Ti and Mn are determined after chemical separation using anionic exchange. The detection limits for a number of other elements are also given. Results for NBS standard reference materials are presented and the results compared with the recommended values. The agreement is good. The results of the analysis of five ancient bronze and two copper objects are presented. (author)

Recrystallization and embrittlement of sintered tungsten

International Nuclear Information System (INIS)

Bega, N.D.; Babak, A.V.; Uskov, E.I.

1982-01-01

The recrystallization of sintered tungsten with a cellular structure of deformation is studied as related to its embrittlement. It is stated that in case of preliminary recrystallization the sintered tungsten crack resistance does not depend on the testing temperature. The tungsten crack resistance is shown to lower with an increase of the structure tendency to primary recrystallization [ru

Tungsten-induced carcinogenesis in human bronchial epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Laulicht, Freda; Brocato, Jason; Cartularo, Laura; Vaughan, Joshua; Wu, Feng; Kluz, Thomas; Sun, Hong [Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, NY 10987 (United States); Oksuz, Betul Akgol [Genome Technology Center, New York University Langone Medical Center, New York, NY 10016 (United States); Shen, Steven [Center for Health Informatics and Bioinformatics, New York University Langone Medical Center, New York, NY 10016 (United States); Peana, Massimiliano; Medici, Serenella; Zoroddu, Maria Antonietta [Department of Chemistry and Pharmacy, University of Sassari, Sassari (Italy); Costa, Max, E-mail: Max.Costa@nyumc.org [Department of Environmental Medicine, New York University Langone Medical Center, Tuxedo, NY 10987 (United States)

2015-10-01

Metals such as arsenic, cadmium, beryllium, and nickel are known human carcinogens; however, other transition metals, such as tungsten (W), remain relatively uninvestigated with regard to their potential carcinogenic activity. Tungsten production for industrial and military applications has almost doubled over the past decade and continues to increase. Here, for the first time, we demonstrate tungsten's ability to induce carcinogenic related endpoints including cell transformation, increased migration, xenograft growth in nude mice, and the activation of multiple cancer-related pathways in transformed clones as determined by RNA sequencing. Human bronchial epithelial cell line (Beas-2B) exposed to tungsten developed carcinogenic properties. In a soft agar assay, tungsten-treated cells formed more colonies than controls and the tungsten-transformed clones formed tumors in nude mice. RNA-sequencing data revealed that the tungsten-transformed clones altered the expression of many cancer-associated genes when compared to control clones. Genes involved in lung cancer, leukemia, and general cancer genes were deregulated by tungsten. Taken together, our data show the carcinogenic potential of tungsten. Further tests are needed, including in vivo and human studies, in order to validate tungsten as a carcinogen to humans. - Highlights: • Tungsten (W) induces cell transformation and increases migration in vitro. • W increases xenograft growth in nude mice. • W altered the expression of cancer-related genes such as those involved in leukemia. • Some of the dysregulated leukemia genes include, CD74, CTGF, MST4, and HOXB5. • For the first time, data is presented that demonstrates tungsten's carcinogenic potential.

Growth of Tungsten Bronze Family Crystals

Science.gov (United States)

1989-03-01

the other weighs the crucible (Technical Specialties and Services (TSS)). Both systems are adequate for our needs, but the TSS system is designed for...507. 47. L.H. Lin, Proc. IEEE 57 (1969), 210. 48. F.S. Chen, J. AppI. Phys. 38 (1967), 3148. 49. E. Okoniata. H-. Ikea and K. Muto, Appi. Opt. 14

Non-invasive PGAA, PIXE and ToF-ND analyses on Hungarian Bronze Age defensive armour

International Nuclear Information System (INIS)

Marianne Moedlinger; Imre Kovacs; Zoltan Szoekefalvi-Nagy; Ziad El Morr

2014-01-01

Non-invasive, archaeometric analyses on selected Hungarian Bronze Age defensive armour is presented here: three greaves, three helmets two shields as well as one vessel fragment were analysed with PIXE, PGAA and TOF-ND. The detected alloy elemental and phase composition as well as its intergranular or spatial concentration distribution reveals important insights into the alloys used and the manufacturing techniques applied c. 1200-950 BC, and allows to reconstruct the production techniques used during the Late Bronze Age. (author)

Environmental fate of tungsten from military use

International Nuclear Information System (INIS)

Clausen, Jay L.; Korte, Nic

2009-01-01

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

7 CFR 51.1145 - U.S. No. 1 Bronze.

Science.gov (United States)

2010-01-01

...) Internal quality: Lots meeting the internal requirements for “U.S. Grade AA Juice (Double A)” or “U.S... 7 Agriculture 2 2010-01-01 2010-01-01 false U.S. No. 1 Bronze. 51.1145 Section 51.1145 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

Study on acoustical properties of sintered bronze porous material for transient exhaust noise of pneumatic system

Science.gov (United States)

Li, Jingxiang; Zhao, Shengdun; Ishihara, Kunihiko

2013-05-01

A novel approach is presented to study the acoustical properties of sintered bronze material, especially used to suppress the transient noise generated by the pneumatic exhaust of pneumatic friction clutch and brake (PFC/B) systems. The transient exhaust noise is impulsive and harmful due to the large sound pressure level (SPL) that has high-frequency. In this paper, the exhaust noise is related to the transient impulsive exhaust, which is described by a one-dimensional aerodynamic model combining with a pressure drop expression of the Ergun equation. A relation of flow parameters and sound source is set up. Additionally, the piston acoustic source approximation of sintered bronze silencer with cylindrical geometry is presented to predict SPL spectrum at a far-field observation point. A semi-phenomenological model is introduced to analyze the sound propagation and reduction in the sintered bronze materials assumed as an equivalent fluid with rigid frame. Experiment results under different initial cylinder pressures are shown to corroborate the validity of the proposed aerodynamic model. In addition, the calculated sound pressures according to the equivalent sound source are compared with the measured noise signals both in time-domain and frequency-domain. Influences of porosity of the sintered bronze material are also discussed.

Medical image registration algorithms assesment Bronze Standard application enactment on grids using the MOTEUR workflow engine

CERN Document Server

Glatard, T; Pennec, X

2006-01-01

Medical image registration is pre-processing needed for many medical image analysis procedures. A very large number of registration algorithms are available today, but their performance is often not known and very difficult to assess due to the lack of gold standard. The Bronze Standard algorithm is a very data and compute intensive statistical approach for quantifying registration algorithms accuracy. In this paper, we describe the Bronze Standard application and we discuss the need for grids to tackle such computations on medical image databases. We demonstrate MOTEUR, a service-based workflow engine optimized for dealing with data intensive applications. MOTEUR eases the enactment of the Bronze Standard and similar applications on the EGEE production grid infrastructure. It is a generic workflow engine, based on current standards and freely available, that can be used to instrument legacy application code at low cost.

Correlation of mechanical properties with nondestructive evaluation of babbitt metal/bronze composite interface

Science.gov (United States)

Ijiri, Y.; Liaw, P. K.; Taszarek, B. J.; Frohlich, S.; Gungor, M. N.

1988-09-01

Interfaces of the babbitt metal-bronze composite were examined ultrasonically and were fractured using the Chalmers test method. It was found that the ultrasonic results correlated with the bond strength, the ductility, and the degree of bonding at the tested interface. Specifically, high ultrasonic reflection percentages were associated with low bond strength, low ductility, and low percentages of bonded regions. The fracture mechanism in the bonded area of the babbitt-bronze interface is related to the presence of the intermetallic compound, Cu6Sn5, at the interface. It is suggested that the non-destructive ultrasonic technique can detect the bond integrity of babbitted metals.

Highly stable aqueous zinc-ion storage using a layered calcium vanadium oxide bronze cathode

Energy Technology Data Exchange (ETDEWEB)

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N. [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

2018-04-03

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn{sup 2+} intercalation chemistry, stand out as they can employ high-capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn{sup 2+} ions in the aqueous electrolyte, we demonstrate that the calcium-based bronze structure can deliver a high capacity of 340 mA h g{sup -1} at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn{sup 2+} storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg{sup -1} at a power density of 53.4 W kg{sup -1}. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

OpenAIRE

Roman Hovsepyan

2011-01-01

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 c...

ITER tungsten divertor design development and qualification program

Energy Technology Data Exchange (ETDEWEB)

Hirai, T., E-mail: takeshi.hirai@iter.org [ITER Organization, Route de Vinon sur Verdon, F-13115 Saint Paul lez Durance (France); Escourbiac, F.; Carpentier-Chouchana, S.; Fedosov, A.; Ferrand, L.; Jokinen, T.; Komarov, V.; Kukushkin, A.; Merola, M.; Mitteau, R.; Pitts, R.A.; Shu, W.; Sugihara, M. [ITER Organization, Route de Vinon sur Verdon, F-13115 Saint Paul lez Durance (France); Riccardi, B. [F4E, c/ Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Suzuki, S. [JAEA, Fusion Research and Development Directorate JAEA, 801-1 Mukouyama, Naka, Ibaragi 311-0193 (Japan); Villari, R. [Associazione EURATOM-ENEA sulla Fusione, Via Enrico Fermi 45, I-00044 Frascati, Rome (Italy)

2013-10-15

Highlights: • Detailed design development plan for the ITER tungsten divertor. • Latest status of the ITER tungsten divertor design. • Brief overview of qualification program for the ITER tungsten divertor and status of R and D activity. -- Abstract: In November 2011, the ITER Council has endorsed the recommendation that a period of up to 2 years be set to develop a full-tungsten divertor design and accelerate technology qualification in view of a possible decision to start operation with a divertor having a full-tungsten plasma-facing surface. To ensure a solid foundation for such a decision, a full tungsten divertor design, together with a demonstration of the necessary high performance tungsten monoblock technology should be completed within the required timescale. The status of both the design and technology R and D activity is summarized in this paper.

Capital Cities in Late Bronze Age Greater Mesopotamia

OpenAIRE

Carlson, Evan

2017-01-01

This dissertation explores the relationships among founding capital cities, defining state territories, and creating and propagating national identities. In the modern period and deep into history, nascent nations struggling to define themselves and unify diverse states have founded capital cities to embody a national ethos, reveal a shared history, direct the relationship among subjects and government, and differentiate a society from its international peers. In the Late Bronze Age (LBA) (15...

Determination of the elemental composition of copper and bronze objects by neutron activation analysis

International Nuclear Information System (INIS)

Hoelttae, P.; Rosenberg, R.J.

1987-01-01

A method for the elemental analysis of copper and bronze objects is described. Na, Co, Ni, Cu, Zn, As, Ag, Sn, Sb, W, Ir and Au are determined through instrumental neutron activation analysis. Mg, Al, V, Ti and Mn are determined after chemical separation using anionic exchange. The detection limits for a number of other elements are also given. Results for NBS standard reference materials are presented and the results are compared with the recommended values. The agreement is good. The results of the analysis of five ancient bronze and two copper objects are also presented. (author) 3 refs.; 4 tabs

Hydrogen permeation properties of plasma-sprayed tungsten*1

Science.gov (United States)

Anderl, R. A.; Pawelko, R. J.; Hankins, M. R.; Longhurst, G. R.; Neiser, R. A.

1994-09-01

Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D 3+ ion beam with fluxes of ˜6.5 × 10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity.

Vapor-transport of tungsten and its geologic application

Energy Technology Data Exchange (ETDEWEB)

Shibue, Y [Hyogo Univ. of Teacher Education, Hyogo (Japan)

1988-11-10

The volatility of tungsten in a hydrous system at elevated temperatures and pressures was examined, and a tentative model for the enrichment of tungsten in hydrothermal solutions for the deposits related to granitic activities was proposed. To produce vapor-saturated solution, 17 or 15ml of 20wt% NaCl solution was introduced into an autoclave. Ca(OH){sub 2} for tungsten and H{sub 2}WO{sub 4} for base metals were used as vapor-captures, and run products were identified by X-ray powder diffractometry. The results suggested that the ratio of tungsten to base metals was higher in a vapor phase than in a liquid phase, and more enrichment of tungsten in the vapor phase occurred at higher temperature and pressure under the coexistence of the vapor and liquid phase. The tentative model emphasizing the vapor-transport of tungsten could explain the presence of tungsten deposits without large mineralization of base metals. Geological schematic model for the generation of the hydrothermal solution enriched in tungsten compared with base metals was illustrated based on above mentioned results. 21 refs., 3 figs.

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.

Tungsten Speciation in Firing Range Soils

Science.gov (United States)

2011-01-01

satisfactorily, such as: which tungsten mineral phase is present in soil and to what extent is adsorption important in regu- lating soil solution concentrations... soil solution rather than discrete mineral phases. Information provided in this report will assist the following organizations in future decision...the soil solution ERDC TR-11-1 43 must affect tungsten speciation in other ways. The precipitation of soil minerals also would limit tungsten

Strain aging in tungsten heavy alloys

International Nuclear Information System (INIS)

Dowding, R.J.; Tauer, K.J.

1991-01-01

This paper reports on tungsten heavy alloys which are two-phase mixtures of body center cubic (BCC) tungsten surrounded by a face center cubic (FCC) matrix. The matrix is most often composed of nickel and iron in a ratio of 70:30 but, occasionally, the matrix may also contain cobalt or copper. Nickel, however, is always the primary matrix component. The tungsten heavy alloy is fabricated through powder metallurgy techniques. Elemental powders are blended, pressed to shape, and sintered. Depending upon the tungsten content, the sintering temperatures are usually in the range of 1450 degrees C to 1525 degrees C. These temperatures are high enough that, as a result, the matrix is at the liquid phase and the process is known as liquid phase sintering. At the liquid phase temperature, the matrix becomes saturated with tungsten, but this does not change the FCC character of the matrix. The sintering is usually done in a hydrogen atmosphere furnace in order to reduce the oxides on the tungsten powder surfaces and create clean, active surfaces which will enhance the adherence between the tungsten and the matrix. The hydrogen atmosphere also creates the presence of excess dissolved hydrogen in the alloy. It has been shown that the hydrogen degrades the toughness and ductility of the heavy alloy. A post-sintering vacuum heat treatment is generally required to insure that there is no residual hydrogen present. The as-sintered tensile strength of a 90% tungsten, 7% nickel, 3% iron alloy (90W) is in the range of 800 to 940 MPa and can be increased significantly by cold working, usually rolling or swaging. Swaging to reductions in area of 20% can result in tensile strengths of 1250 MPa or more. As the strength increases, the elongation, which may have been 30% or more, decreases to less than 5%

Production and release of gas and volatile elements from sodium-based targets

CERN Multimedia

Plewinski, F; Wildner, E; Catherall, R

Several large scale facilities being studied for Europe use sodium or a sodium-based alloy either as a target or as a coolant for heavier solid targets subjected to MW proton beams, such as the European Spallation Source (ESS) and $\\beta$-beam projects. ESS will be the neutron source in use from the year 2020 in Europe, providing high intensity neutron fluxes over large energy spectra ( from 10$^{-3}$ eV to 10$^{3}$ eV) to scientists, to explore materials from 10$^{-2}$m to 10$^{-16}$m scale. A sodium-cooled array of tungsten blocks is one of the potential solutions for the target that will convert protons from the 5 MW 2.5 GeV linac into neutrons. Sodium is a tried and tested coolant in fast nuclear reactors with associated technologies and design standards. Its application to a spallation environment however remains to be validated. The ISOLDE facility is well placed to perform detailed measurements of radioisotopes produced in sodium with a proton beam whose energy of 1.4 GeV is very close to the ESS base...

Development and manufacturing of bronze-processed Ta-added Nb3Sn wires for the ITER

International Nuclear Information System (INIS)

Kikuchi, Kenichi; Seidou, Masahiro; Iwaki, Genzou; Sakai, Syuuji; Moriai, Hidezumi; Nishi, Masataka; Yoshida, Kiyoshi; Isono, Takaaki; Tsuji, Hiroshi.

1997-01-01

Development work to produce a high-performance Nb 3 Sn superconducting wire for the center solenoid coil of the ITER was carried out. The effects of concurrently adding Ti and Ta to bronze-processed Nb 3 Sn wires were examined. In addition, a high-Sn-concentration bronze matrix was applied. Then, the relation between hysteresis loss and filament diameter was examined. Moreover, the cause of wire breakage during processing was elucidated. As a result, a reliable manufacturing process for high-performance Nb 3 Sn superconducting wire was established. (author)

Chemically deposited tungsten fibre-reinforced tungsten – The way to a mock-up for divertor applications

Directory of Open Access Journals (Sweden)

J. Riesch

2016-12-01

Full Text Available The development of advanced materials is essential for sophisticated energy systems like a future fusion reactor. Tungsten fibre-reinforced tungsten composites (Wf/W utilize extrinsic toughening mechanisms and therefore overcome the intrinsic brittleness of tungsten at low temperature and its sensitivity to operational embrittlement. This material has been successfully produced and tested during the last years and the focus is now put on the technological realisation for the use in plasma facing components of fusion devices. In this contribution, we present a way to utilize Wf/W composites for divertor applications by a fabrication route based on the chemical vapour deposition (CVD of tungsten. Mock-ups based on the ITER typical design can be realized by the implementation of Wf/W tiles. A concept based on a layered deposition approach allows the production of such tiles in the required geometry. One fibre layer after the other is positioned and ingrown into the W-matrix until the final sample size is reached. Charpy impact tests on these samples showed an increased fracture energy mainly due to the ductile deformation of the tungsten fibres. The use of Wf/W could broaden the operation temperature window of tungsten significantly and mitigate problems of deep cracking occurring typically in cyclic high heat flux loading. Textile techniques are utilized to optimise the tungsten wire positioning and process speed of preform production. A new device dedicated to the chemical deposition of W enhances significantly, the available machine time for processing and optimisation. Modelling shows that good deposition results are achievable by the use of a convectional flow and a directed temperature profile in an infiltration process.

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

Fabrication of tungsten wire needles

International Nuclear Information System (INIS)

Roder, A.

1983-02-01

Fine point needles for field emissoin are conventionally produced by electrolytically or chemically etching tungsten wire. Points formed in this manner have a typical tip radius of about 0.5 microns and a cone angle of some 30 degrees. The construction of needle matrix detector chambers has created a need for tungsten needles whose specifications are: 20 mil tungsten wire, 1.5 inch total length, 3 mm-long taper (resulting in a cone angle of about 5 degrees), and 25 micron-radius point (similar to that found on sewing needles). In the process described here for producing such needles, tungsten wire, immersed in a NaOH solution and in the presence of an electrode, is connected first to an ac voltage and then to a dc supply, to form a taper and a point on the end of the wire immersed in the solution. The process parameters described here are for needles that will meet the above specifications. Possible variations will be discussed under each approprite heading

The tungsten powder study of the dispenser cathode

International Nuclear Information System (INIS)

Bao Jixiu; Wan Baofei

2006-01-01

The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 deg. C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment

The tungsten powder study of the dispenser cathode

Science.gov (United States)

Bao, Ji-xiu; Wan, Bao-fei

2006-06-01

The intercorrelation of tungsten powder properties, such as grain size, distribution and morphology, and porous matrix parameters with electron emission capability and longevity of Ba dispenser cathodes has been investigated for the different grain morphologies. It is shown that a fully cleaning step of the tungsten powder is so necessary that the tungsten powder will be reduction of oxide in hydrogen atmosphere above 700 °C. The porosity of the tungsten matrix distributes more even and the closed pore is fewer, the average granule size of the tungsten powder distributes more convergent. The porosity of the tungsten matrix and the evaporation of the activator are bigger and the pulse of the cathode is smaller when the granularity is bigger by the analysis of the electronic microscope and diode experiment.

Tribological wear behavior of diamond reinforced composite coating

International Nuclear Information System (INIS)

Venkateswarlu, K.; Ray, Ajoy Kumar; Gunjan, Manoj Kumar; Mondal, D.P.; Pathak, L.C.

2006-01-01

In the present study, diamond reinforced composite (DRC) coating has been applied on mild steel substrate using thermal spray coating technique. The composite powder consists of diamond, tungsten carbide, and bronze, which was mixed in a ball mill prior deposition by thermal spray. The microstructure and the distribution of diamond and tungsten carbide particle in the bronze matrix were studied. The DRC-coated mild steel substrates were assessed in terms of their high stress abrasive wear and compared with that of uncoated mild steel substrates. It was observed that when sliding against steel, the DRC-coated sample initially gains weight, but then loses the transferred counter surface material. In case of abrasive wear, the wear rate was greatly reduced due to the coating; wherein the wear rate decreased with increase in diamond content

An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings

Science.gov (United States)

Wensheng, Li; Wang, S. C.; Ma, Chao; Zhiping, Wang

2012-07-01

The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature.

Tungsten or Wolfram: Friend or Foe?

Science.gov (United States)

Zoroddu, Maria A; Medici, Serenella; Peana, Massimiliano; Nurchi, Valeria M; Lachowicz, Joanna I; Laulicht-Glickc, Freda; Costa, Max

2018-01-01

Tungsten or wolfram was regarded for many years as an enemy within the tin smelting and mining industry, because it conferred impurity or dirtiness in tin mining. However, later it was considered an amazing metal for its strength and flexibility, together with its diamond like hardness and its melting point which is the highest of any metal. It was first believed to be relatively inert and an only slightly toxic metal. Since early 2000, the risk exerted by tungsten alloys, its dusts and particulates to induce cancer and several other adverse effects in animals as well as humans has been highlighted from in vitro and in vivo experiments. Thus, it becomes necessary to take a careful look at all the most recent data reported in the scientific literature, covering the years 2001-2016. In fact, the findings indicate that much more attention should be devoted to thoroughly investigate the toxic effects of tungsten and the involved mechanisms of tungsten metal or tungsten metal ions. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Investigating of the Field Emission Performance on Nano-Apex Carbon Fiber and Tungsten Tips

Science.gov (United States)

Mousa, Marwan S.; Alnawasreh, Shadi; Madanat, Mazen A.; Al-Rabadi, Anas N.

2015-10-01

Field electron emission measurements have been performed on carbon-based and tungsten microemitters. Several samples of both types of emitters with different apex radii have been obtained employing electrolytic etching techniques using sodium hydroxide (NaOH) solution with different molarities depending on the material used. A suitable, home-built, field electron microscope (FEM) with 10 mm tip to screen separation distance was used to electrically characterize the electron emitters. Measurements were carried out under ultra high vacuum (UHV) conditions with base pressure of 10-9 mbar. The current-voltage characteristics (I-V) presented as Fowler-Nordheim (FN) type plots, and field electron emission images have been recorded. In this work, initial comparison of the field electron emission performance of these micro and nanoemitters has been carried out, with the aim of obtaining a reliable, stable and long life powerful electron source. We compare the apex radii measured from the micrographs obtained from the SEM images to those extracted from the FN-type _I-V_plots for carbon fibers and tungsten tips.

Investigating of the Field Emission Performance on Nano-Apex Carbon Fiber and Tungsten Tips

International Nuclear Information System (INIS)

Mousa, Marwan S; Alnawasreh, Shadi; Al-Rabadi, Anas N; Madanat, Mazen A

2015-01-01

Field electron emission measurements have been performed on carbon-based and tungsten microemitters. Several samples of both types of emitters with different apex radii have been obtained employing electrolytic etching techniques using sodium hydroxide (NaOH) solution with different molarities depending on the material used. A suitable, home-built, field electron microscope (FEM) with 10 mm tip to screen separation distance was used to electrically characterize the electron emitters. Measurements were carried out under ultra high vacuum (UHV) conditions with base pressure of 10 -9 mbar. The current-voltage characteristics (I-V) presented as Fowler-Nordheim (FN) type plots, and field electron emission images have been recorded. In this work, initial comparison of the field electron emission performance of these micro and nanoemitters has been carried out, with the aim of obtaining a reliable, stable and long life powerful electron source. We compare the apex radii measured from the micrographs obtained from the SEM images to those extracted from the FN-type -I-V-plots for carbon fibers and tungsten tips. (paper)

Artefact biography 2.0 : the information value of corroded archaeological bronzes

NARCIS (Netherlands)

Nienhuis, J.

2017-01-01

The different phases in the life of archaeological objects can be described by artefact biography. This dissertation defines an updated version: artefact biography 2.0, and the life phases of Early Iron Age bronze studs from Oss-Zevenbergen, the Netherlands, are elaborated. Throughout the thesis,

Thermal Spray Coating of Tungsten for Tokamak Device

International Nuclear Information System (INIS)

Jiang Xianliang; Gitzhofer, F; Boulos, M I

2006-01-01

Thermal spray, such as direct current (d.c.) plasma spray or radio frequency induced plasma spray, was used to deposit tungsten coatings on the copper electrodes of a tokamak device. The tungsten coating on the outer surface of one copper electrode was formed directly through d.c. plasma spraying of fine tungsten powder. The tungsten coating/lining on the inner surface of another copper electrode could be formed indirectly through induced plasma spraying of coarse tungsten powder. Scanning electron microscopy (SEM) was used to examine the cross section and the interface of the tungsten coating. Energy Dispersive Analysis of X-ray (EDAX) was used to analyze the metallic elements attached to a separated interface. The influence of the particle size of the tungsten powder on the density, cracking behavior and adhesion of the coating is discussed. It is found that the coarse tungsten powder with the particle size of 45 ∼ 75 μm can be melted and the coating can be formed only by using induced plasma. The coating deposited from the coarse powder has much higher cohesive strength, adhesive strength and crack resistance than the coating made from the fine powder with a particle size of 5 μm

Operation of ASDEX Upgrade with tungsten coated walls

International Nuclear Information System (INIS)

Rohde, V.

2002-01-01

An alternative for low-Z materials in the main chamber of a future fusion device are high-Z materials, but the maximal tolerable concentration in the plasma core is restricted. A step by step approach to employ tungsten at the central column of ASDEX Upgrade was started in 1999. Meanwhile almost the whole central column is covered with tiles, which were coated by PVD with tungsten. Up to now 9000 s of plasma discharge covering all relevant scenarios were performed. Routine operation of ASDEX Upgrade was not affected by the tungsten. Typical concentrations below 10 -5 were found. The tungsten concentration is mostly connected to the transport into the core plasma, not to the tungsten erosion. It can be demonstrated, that additional central heating can eliminate the tungsten accumulation. These experiments demonstrate the compatibility of fusion plasmas with W plasma facing components under reactor relevant conditions. The erosion pattern found by post mortem analysis indicates that the main effect is ion sputtering. The main erosion of tungsten seems to occur during plasma ramp-up and ramp-down. (author)

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.

Tungsten Targets the Tumor Microenvironment to Enhance Breast Cancer Metastasis

Science.gov (United States)

Bolt, Alicia M.; Sabourin, Valérie; Molina, Manuel Flores; Police, Alice M.; Negro Silva, Luis Fernando; Plourde, Dany; Lemaire, Maryse; Ursini-Siegel, Josie; Mann, Koren K.

2015-01-01

The number of individuals exposed to high levels of tungsten is increasing, yet there is limited knowledge of the potential human health risks. Recently, a cohort of breast cancer patients was left with tungsten in their breasts following testing of a tungsten-based shield during intraoperative radiotherapy. While monitoring tungsten levels in the blood and urine of these patients, we utilized the 66Cl4 cell model, in vitro and in mice to study the effects of tungsten exposure on mammary tumor growth and metastasis. We still detect tungsten in the urine of patients’ years after surgery (mean urinary tungsten concentration at least 20 months post-surgery = 1.76 ng/ml), even in those who have opted for mastectomy, indicating that tungsten does not remain in the breast. In addition, standard chelation therapy was ineffective at mobilizing tungsten. In the mouse model, tungsten slightly delayed primary tumor growth, but significantly enhanced lung metastasis. In vitro, tungsten did not enhance 66Cl4 proliferation or invasion, suggesting that tungsten was not directly acting on 66Cl4 primary tumor cells to enhance invasion. In contrast, tungsten changed the tumor microenvironment, enhancing parameters known to be important for cell invasion and metastasis including activated fibroblasts, matrix metalloproteinases, and myeloid-derived suppressor cells. We show, for the first time, that tungsten enhances metastasis in an animal model of breast cancer by targeting the microenvironment. Importantly, all these tumor microenvironmental changes are associated with a poor prognosis in humans. PMID:25324207

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)

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 (...

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

International Nuclear Information System (INIS)

Calcagnile, L.; D'Elia, M.; Quarta, G.; Vidale, M.

2010-01-01

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.

Processing of tungsten scrap into powders by electroerosion disintegration

International Nuclear Information System (INIS)

Fominskii, L.P.; Leuchuk, M.V.; Myuller, A.S.; Tarabrina, V.P.

1985-01-01

Utilization of tungsten and tungsten alloy swarf and other waste and also of rejected and worn parts is a matter of great importance in view of the shortage of this metal. The authors examine the electroerosion (EE) disintegration of tungsten in water as a means of utilizing swarf and other loose waste. Unlike chemical methods, EE disintegration ensures ecological purity since there are no effluent waters or toxic discharges. Swarf and trimmings of rods of diameters up to 20 mm obtained after the lathe-turning of tungsten bars sintered from PVN and PVV tungsten powders were disintegrated in water at room temperature between tungsten electrodes. The phase composition of the powder was studied using FeK /SUB alpha/ radiation, by x-ray diffraction methods in a DRON-2 diffractometer with a graphite monochromator on the secondary beam. When tungsten is heated to boiling during EE disintegration, the impurities present in it can evaporate and burn out. Thus, tungsten powder produced by EE disintegration can be purer than the starting metal

Solvent extraction in analytical chemistry of tungsten (Review)

International Nuclear Information System (INIS)

Ivanov, V.M.; Busev, A.I.; Sokolova, T.A.

1975-01-01

The use of extraction for isolating and concentrating tungsten with subsequent determination by various methods is considered. For tungsten extractants of all types are employed: neutral, basic and acidic. Neutral extractants are used for isolating and concentrating tungsten, basic and acidic ones are employed, as a rule, for the isolation and subsequent determination of tungsten. This type of extractants is highly promising, since, selectively extracting tungsten, they allow its simultaneous determination. Neutral extractants are oxygen-containing solvents, TBP; basic extractants are aniline, pyridine, 1-naphthylamine, trialkylbenzylammoniumanitrate. As acidic reagents use is made of 8-oxyquinoline and its derivatives, oximes and hydroxamic acids, β-diketones, carbaminates. In the extraction radioactive isotope 185 W is employed

The influence of wall thickness on the microstructure of bronze BA1055 with the additions of Si, Cr, Mo and/or W

Directory of Open Access Journals (Sweden)

B.P. Pisarek

2008-12-01

Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, about good 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. Additions Mo and/or W were not applied so far in the larger concentration, these elements were introduced to the melts of the copper as the components of modifiers. 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 influence of the wall thickness of the cast on size of crystallites were conducted: the primary phase β and intermetallic phase κ and the width separates of the secondary phase α precipitate at phase boundary. It results from conducted investigations, that in the aluminium bronze BA1055 after simultaneous makes additions Si, Cr, Mo and in the primary phase β it undergoes considerable reducing size. The addition W reduce size of the grain phase β in the thin walls of the cast 3-6 mm, and addition Cr in the range of the thickness of the wall of the cast 3-6 mm it favors to reducing size the phase β, in walls 12-25 mm the growth causes it. The addition Mo does not influence the change of the size of the grain of the β phase significantly. The make addition singly or simultaneously of the Cr, Mo and W to the bronze CuAl10Fe5Ni5Si it influences the decrease of the quantity separates of the phase α on the interface boundary and of width it separates independently from the thickness of the wall of the cast. The simultaneous make addition of the Si, Cr, Mo and W it enlarges the surface of the phase κFe, κMo. The make addition to the bronze CuAl10Fe5Ni5Si of the Cr, Mo or W the quantity of crystallizing hard phase κ enlarges and the

Evaluation of some non-toxic thiadiazole derivatives as bronze corrosion inhibitors in aqueous solution

International Nuclear Information System (INIS)

Varvara, Simona; Muresan, Liana Maria; Rahmouni, Kamal; Takenouti, Hisasi

2008-01-01

The inhibiting effect of four innoxious thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole (MAT), 2-mercapto-5-acetylamino-1,3,4-thiadiazole (MAcAT), 2-mercapto-5-methyl-1,3,4-thiadiazole (MMeT) and 2-mercapto-5-phenylamino-1,3,4-thiadiazole (MPhAT)) on bronze corrosion in an aerated solution of 0.2 g L -1 Na 2 SO 4 + 0.2 g L -1 NaHCO 3 at pH 5 was studied by potentiodynamic voltammetry and electrochemical impedance spectroscopy. The corrosion parameters determined from the polarisation curves indicate that the addition of the investigated thiadiazole derivatives decreases both cathodic and anodic current densities, due to an inhibition of the corrosion process, through the adsorption of thiadiazoles on the bronze surface. The inhibiting effect of the investigated organic compounds appears to be more pronounced on the anodic process than on the cathodic one and, except for the case MPhAT, it is enhanced by the increases of the inhibitors' concentration. The adsorption of the thiadiazole derivatives on bronze was confirmed by the presence of the nitrogen atoms in the EDX spectra of the bronze exposed to inhibitor-containing solutions. The magnitude of polarisation resistance values and, consequently, the inhibition efficiencies are influenced by the molecular structure of thiadiazole derivatives. The strongest inhibition was noticed in the presence of compounds with phenyl amino- or amino-functionalities in their molecules. The maximum protection efficiencies were obtained by addition of: 5 mM MAT (95.9%), 1 mM MAcAT (95.7%), 5 mM MMeT (92.6%) and 0.1 mM MPhAT (97%). EIS measurements also revealed that the inhibitor effectiveness of the optimal concentrations of thiadiazole is time-dependent

Evaluation of some non-toxic thiadiazole derivatives as bronze corrosion inhibitors in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Varvara, Simona [Department of Topography, ' 1 Decembrie 1918' University, 11-13 Nicolae Iorga Street, 510009 Alba Iulia (Romania); Muresan, Liana Maria [Department of Physical Chemistry, ' Babes-Bolyai' University, 11 Arany-Janos Street, 400028 Cluj-Napoca (Romania)], E-mail: limur@chem.ubbcluj.ro; Rahmouni, Kamal; Takenouti, Hisasi [UPMC LISE - UPR 15 of the CNRS, ' Pierre and Marie Curie' University, Paris (France)

2008-09-15

The inhibiting effect of four innoxious thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole (MAT), 2-mercapto-5-acetylamino-1,3,4-thiadiazole (MAcAT), 2-mercapto-5-methyl-1,3,4-thiadiazole (MMeT) and 2-mercapto-5-phenylamino-1,3,4-thiadiazole (MPhAT)) on bronze corrosion in an aerated solution of 0.2 g L{sup -1} Na{sub 2}SO{sub 4} + 0.2 g L{sup -1} NaHCO{sub 3} at pH 5 was studied by potentiodynamic voltammetry and electrochemical impedance spectroscopy. The corrosion parameters determined from the polarisation curves indicate that the addition of the investigated thiadiazole derivatives decreases both cathodic and anodic current densities, due to an inhibition of the corrosion process, through the adsorption of thiadiazoles on the bronze surface. The inhibiting effect of the investigated organic compounds appears to be more pronounced on the anodic process than on the cathodic one and, except for the case MPhAT, it is enhanced by the increases of the inhibitors' concentration. The adsorption of the thiadiazole derivatives on bronze was confirmed by the presence of the nitrogen atoms in the EDX spectra of the bronze exposed to inhibitor-containing solutions. The magnitude of polarisation resistance values and, consequently, the inhibition efficiencies are influenced by the molecular structure of thiadiazole derivatives. The strongest inhibition was noticed in the presence of compounds with phenyl amino- or amino-functionalities in their molecules. The maximum protection efficiencies were obtained by addition of: 5 mM MAT (95.9%), 1 mM MAcAT (95.7%), 5 mM MMeT (92.6%) and 0.1 mM MPhAT (97%). EIS measurements also revealed that the inhibitor effectiveness of the optimal concentrations of thiadiazole is time-dependent.

Surface energy anisotropy of tungsten

Energy Technology Data Exchange (ETDEWEB)

Kumar, R; Grenga, H E [Georgia Inst. of Tech., Atlanta (USA). School of Chemical Engineering

1976-10-01

Field-ion microscopy was used to study the faceting behavior and/or surface energy anisotropy of tungsten in vacuum and in hydrogen. In vacuum below 1700 K the activation energy for (110) facet growth agreed with values previously reported for surface diffusion on tungsten. The observed anisotropy values at 0.5 Tsub(m), where Tsub(m) is the absolute melting temperature of tungsten (approximately 3680 K), were different from those previously reported at higher temperatures and more nearly agreed with broken bond calculations based on Mie potential using m=5, n=8, and a 1.5% lattice expansion. Hydrogen appeared to have a negligible effect on surface energy anisotropy, but did preferentially increase surface diffusion rates on (310) regions.

High Heat Load Properties of Ultra Fine Grain Tungsten

International Nuclear Information System (INIS)

Zhou, Z.; Du, J.; Ge, C.; Linke, J.; Pintsuk, G.; Song, S.X.

2007-01-01

Full text of publication follows: Tungsten is increasingly considered as a promising candidate armour materials facing the plasma in tokamaks for medium to high heat flux components (EAST, ASDEX, ITER). Fabrication tungsten with ultra fine grain size is considered as an effective way to ameliorate some disadvantages of tungsten, such as its brittleness at room temperature. But the research data on the performance of ultra fine grain tungsten is still very limit. In this work, high heat load properties of pure ultra-fine grain tungsten have been studied. The ultra fine grain tungsten samples with average grain size of 0.2 μm, 1 μm and 3 μm were fabricated by resistance sintering under ultra high pressure. The annealing experiments for the investigation of the material resistance against grain growth have been done by annealing samples in a vacuum furnace at different temperature holding for 2 hours respectively. It is found that recrystallization and grain growth occur at heating temperature of 1250 deg. c. The finer the initial grain sizes of tungsten, the smaller its grain growth grain. The effects of transient high thermal loads (off normal events like disruptions) on tungsten surface morphology have been performed in electron beam test facility JUDITH. The thermal loads tests have been carried out with 4 ms pulses at different power density of 0.22, 0.33, 0.44, 0.55 and 0.88 GW/m 2 respectively. Horizontal cracks formed for all tungsten samples at 0.44 GW/m 2 . Particle erosions occurred for tungsten with 3 μm size at 0.33 GW/m 2 and for tungsten with 0.2 and 1 μm size at 0.55 GW/m 2 . The weight loss of tungsten with 0.2, 1 and 3 μm size are 2,0.1,0.6 mg respectively at 0.88 GW/m 2 . The effects of a large number of very short transient repetitive thermal loads (ELM-like) on tungsten surface morphology also have been performed by using a fundamental wave of a YAG laser. It is found that tungsten with 0.2 μm size has the best performance. (authors)

High Heat Load Properties of Ultra Fine Grain Tungsten

Energy Technology Data Exchange (ETDEWEB)

Zhou, Z.; Du, J.; Ge, C. [Lab. of Special Ceramic and P/M, University of Science and Technology, 100083 Beijing (China); Linke, J.; Pintsuk, G. [FZJ-Forschungszentrum Juelich GmbH, Association Euratom-FZJ, Institut fur Plasmaphysik, Postfach 1913, D-52425 Juelich (Germany); Song, S.X. [Research Center on Fusion Materials (RCFM), University of Science and Technology Beijing (USTB), 100083 Beijing (China)

2007-07-01

Full text of publication follows: Tungsten is increasingly considered as a promising candidate armour materials facing the plasma in tokamaks for medium to high heat flux components (EAST, ASDEX, ITER). Fabrication tungsten with ultra fine grain size is considered as an effective way to ameliorate some disadvantages of tungsten, such as its brittleness at room temperature. But the research data on the performance of ultra fine grain tungsten is still very limit. In this work, high heat load properties of pure ultra-fine grain tungsten have been studied. The ultra fine grain tungsten samples with average grain size of 0.2 {mu}m, 1 {mu}m and 3 {mu}m were fabricated by resistance sintering under ultra high pressure. The annealing experiments for the investigation of the material resistance against grain growth have been done by annealing samples in a vacuum furnace at different temperature holding for 2 hours respectively. It is found that recrystallization and grain growth occur at heating temperature of 1250 deg. c. The finer the initial grain sizes of tungsten, the smaller its grain growth grain. The effects of transient high thermal loads (off normal events like disruptions) on tungsten surface morphology have been performed in electron beam test facility JUDITH. The thermal loads tests have been carried out with 4 ms pulses at different power density of 0.22, 0.33, 0.44, 0.55 and 0.88 GW/m{sup 2} respectively. Horizontal cracks formed for all tungsten samples at 0.44 GW/m{sup 2}. Particle erosions occurred for tungsten with 3 {mu}m size at 0.33 GW/m{sup 2} and for tungsten with 0.2 and 1 {mu}m size at 0.55 GW/m{sup 2}. The weight loss of tungsten with 0.2, 1 and 3 {mu}m size are 2,0.1,0.6 mg respectively at 0.88 GW/m{sup 2}. The effects of a large number of very short transient repetitive thermal loads (ELM-like) on tungsten surface morphology also have been performed by using a fundamental wave of a YAG laser. It is found that tungsten with 0.2 {mu}m size has

Metal Adornments of Clothing and Headwear in the Bronze Age of Western Siberia (issues of research and reconstruction ..

Directory of Open Access Journals (Sweden)

Umerenkova Olga V.

2017-09-01

Full Text Available The article considers issues related to the principals of scientific approach, methods and procedure of costume reconstruction on the basis of archaeological materials dating back to the Bronze Age discovered in the territory of Western Siberia. The costume is considered by researchers as one of the brightest manifestations of material culture. Its decoration provides multidisciplinary information containing elements of ideology and aesthetic norms together with traditions and social relationships. Reconstruction of clothing and headwear adornments in archaeological literature related to the Bronze Age is one of the understudied topics. Researchers use various sources for its recreation: archaeological materials, written historical, literature and folklore sources, and fine art items. A significant amount of source items has accumulated over the last decades, although the analysis and principles of processing thereof have not been sufficiently covered in special literature. In order to increase the informative capabilities of adornments as sources for the reconstruction of the Bronze Age costume, the author suggested a scheme of accounting for the location of adornments with respect to the remains of the buried when the excavations are documented. The article features the results of the author's reconstruction of women's headwear decoration with metal articles executed on the basis of Bronze Age materials.

The influence of Fe content on spreading ability of tungsten heavy alloys matrix on tungsten surface

Directory of Open Access Journals (Sweden)

A. Krzyńska

2011-07-01

Full Text Available The results of experimental study of tungsten spreading ability with W-Ni-Co-Fe matrix are presented. The aim of these investigations was to see how Fe concentration in W – Ni – Co matrix influences the wettability of tungsten grains during liquid phase sintering. Four green compact specimens containing 50%W, 10%Co and Ni + Fe = 40% but with different Ni to Fe ratio were prepared. The cylindrical specimen 5mm diameter and 5mm height were put on clean pure tungsten substrate and then 20 minutes heated at 1520oC in hydrogen atmosphere. After heating the specimens were carefully measured and then the specimens for structure observations were prepared. It was concluded, that increase of Fe content decrease the melting temperature of W – Ni – Co alloy. The melting point decrease caused by Fe content increase substantially the spreading ability of tungsten substrate with W – Ni – Co alloy. Metallography investigations showed some microstructure changes in “reaction zone” identified in tungsten substrate – (WNi40-xCo10Fex interface. The results of the study confirmed our earlier observations that even relative small Fe addition promotes Weight Heavy Alloys (WHA liquid phase sintering.

Tungsten--carbide critical assembly

International Nuclear Information System (INIS)

Hansen, G.E.; Paxton, H.C.

1975-06-01

The tungsten--carbide critical assembly mainly consists of three close-fitting spherical shells: a highly enriched uranium shell on the inside, a tungsten--carbide shell surrounding it, and a steel shell on the outside. Ideal critical specifications indicate a rather low computed value of k/sub eff/. Observed and calculated fission-rate distributions for 235 U, 238 U, and 237 Np are compared, and calculated leakage neutrons per fission in various energy groups are given. (U.S.)

Electrokinetic treatment of firing ranges containing tungsten-contaminated soils

International Nuclear Information System (INIS)

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

2007-01-01

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

Low temperature processing of tungsten-fibre high-strength composite

International Nuclear Information System (INIS)

Semrau, W.M.

2001-01-01

A tungsten nickel/iron compound with a high tungsten content up to over 90 percent by volume of tungsten and an ideal distribution of the nickel-iron multilayer-matrix avoiding tungsten - tungsten interfaces, has been processed without the use of any sintering process and thus resulted in avoiding temperatures of above 700 o C during the entire manufacturing process. An electrochemical coating of coarse tungsten powder with alternating layers of nickel and iron and a forging process at temperatures not exceeding 650 o C resulted in a high strength compound, which easily could be altered into a tungsten fiber compound with a fiber-length to fiber-diameter ratio of more than 10 3 . From the viewpoint of the metallurgist, easier handling systems are obtained when both a liquid phase and high temperatures with their risks for grain structures and grain boundaries are lacking. (author)

Structure of tungsten electrodeposited from oxide chloride-fluoride molten salts

International Nuclear Information System (INIS)

Pavlovskij, V.A.; Reznichenko, V.A.

1998-01-01

Investigation results on the influence of electrolysis parameters and electrolyte composition on tungsten cathode deposit structure are presented. The electrolysis was performed in NaCl-NaF-WO 3 molten salts using tungsten and tungsten coated molybdenum cathodes. Morphological and metallographic studies of tungsten crystals were carrier out. Tungsten deposits were obtained in the form of crystalline conglomerates, sponge and high dispersity powder

Investigation of vanadium oxide bronzes of phase β by means of annihilation of positrons

International Nuclear Information System (INIS)

Dryzek, E.

1992-01-01

The vanadium bronzes with general composition M x V 2 O 5 (where M means the donor element Li, Na, K, Cu, Na) have been the object of the investigation. The positron annihilation method as well as the broadening of the annihilation line in Doppler spectra have been the basing methods for the study of material structure. The donor lattice vacancies have been investigated as a positron traps being responsible for the shape of annihilation spectra. The model of clustering of donor ions has been constructed. On that base and temperature dependence of the positron annihilation spectra the thermodynamical parameters of donor ion vacancies in vanadium bronzes have been calculated. 112 refs, 33 figs, 11 tabs

Cold spraying of aluminum bronze on profiled submillimeter cermet structures formed by laser cladding

Science.gov (United States)

Ryashin, N. S.; Malikov, A. G.; Shikalov, V. S.; Gulyaev, I. P.; Kuchumov, B. M.; Klinkov, S. V.; Kosarev, V. F.; Orishich, A. M.

2017-10-01

The paper presents results of the cold spraying of aluminum bronze coatings on substrates profiled with WC/Ni tracks obtained by laser cladding. Reinforcing cermet frames shaped as grids with varied mesh sizes were clad on stainless steel substrates using a CO2 laser machine "Siberia" (ITAM SB RAS, Russia). As a result, surfaces/substrates with heterogeneous shape, composition, and mechanical properties were obtained. Aluminum bronze coatings were deposited from 5lF-NS powder (Oerlikon Metco, Switzerland) on those substrates using cold spraying equipment (ITAM SB RAS). Data of profiling, microstructure diagnostics, EDS analysis, and mechanical tests of obtained composites is reported. Surface relief of the sprayed coatings dependence on substrate structure has been demonstrated.

NUMERICAL MODELING OF HARDENING OF UNINTERRUPTEDLY-CASTED BRONZE CASTING

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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.

Bronze-mean hexagonal quasicrystal

Science.gov (United States)

Dotera, Tomonari; Bekku, Shinichi; Ziherl, Primož

2017-10-01

The most striking feature of conventional quasicrystals is their non-traditional symmetry characterized by icosahedral, dodecagonal, decagonal or octagonal axes. The symmetry and the aperiodicity of these materials stem from an irrational ratio of two or more length scales controlling their structure, the best-known examples being the Penrose and the Ammann-Beenker tiling as two-dimensional models related to the golden and the silver mean, respectively. Surprisingly, no other metallic-mean tilings have been discovered so far. Here we propose a self-similar bronze-mean hexagonal pattern, which may be viewed as a projection of a higher-dimensional periodic lattice with a Koch-like snowflake projection window. We use numerical simulations to demonstrate that a disordered variant of this quasicrystal can be materialized in soft polymeric colloidal particles with a core-shell architecture. Moreover, by varying the geometry of the pattern we generate a continuous sequence of structures, which provide an alternative interpretation of quasicrystalline approximants observed in several metal-silicon alloys.

Tungsten carbide and tungsten-molybdenum carbides as automobile exhaust catalysts

International Nuclear Information System (INIS)

Leclercq, L.; Daubrege, F.; Gengembre, L.; Leclercq, G.; Prigent, M.

1987-01-01

Several catalyst samples of tungsten carbide and W, Mo mixed carbides with different Mo/W atom ratios, have been prepared to test their ability to remove carbon monoxide, nitric oxide and propane from a synthetic exhaust gas simulating automobile emissions. Surface characterization of the catalysts has been performed by X-ray photoelectron spectroscopy (XPS) and selective chemisorption of hydrogen and carbon monoxide. Tungsten carbide exhibits good activity for CO and NO conversion, compared to a standard three-way catalyst based on Pt and Rh. However, this W carbide is ineffective in the oxidation of propane. The Mo,W mixed carbides are markedly different having only a very low activity. 9 refs.; 10 figs.; 5 tabs

Influence of heating rates on in situ resistance measurements of a bronze route Nb-Sn-Cu-Ta multifilamentary conductor

International Nuclear Information System (INIS)

Tan, K.S.; Hopkins, S.C.; Glowacki, B.A.

2004-01-01

The superconducting properties of a bronze process multifilamentary conductor are controlled by the structure, dimensions and composition of the intermetallic layers, which are strongly influenced by the details of the heat treatments applied to the conductor. It has previously been reported that the electrical resistivity of a Vacuumschmelze bronze process conductor varies during heat treatment, and that analysis of the conductor as a set of parallel resistors allows the features of the resistivity variation to be assigned to the progress of Nb 3 Sn intermetallic phase formation. The behaviour of NSP2 Nb-Sn-Cu-Ta bronze process multifilamentary conductors (Imperial Metal Industries) is now reported as a function of the heating rate, in preparation for more complex non-isothermal heat treatment procedures. It is shown that the resistance of the wire measured in situ by an alternating current (AC) technique can be used to observe the progress of the formation of Nb 3 Sn, and that the comparison of resistometric measurements at different heating rates can give an indication of other processes (such as recovery and recrystallisation) occurring at lower temperatures during the heating up process prior to isothermal annealing. In addition, this wire containing only about 1% of copper was carefully chosen because of the broken tantalum barriers around individual copper filaments. Therefore, the resistometric measurements were used to attempt to detect the diffusion of tin from the bronze matrix into the copper filaments at lower temperatures without noticeable influence on Nb 3 Sn phase formation. Treating the NSP2 wire as a set of parallel resistors also permits estimates to be made of the intermetallic layer thicknesses from resistometric measurements, and these are shown to be in good agreement with estimates from scanning electron microscopy. The difference in critical temperature, T c , between wires heated at different rates, with the presence of the bronze matrix

Detection and reduction of tungsten contamination in ion implantation processes

International Nuclear Information System (INIS)

Polignano, M.L.; Galbiati, A.; Grasso, S.; Mica, I.; Barbarossa, F.; Magni, D.

2016-01-01

In this paper, we review the results of some studies addressing the problem of tungsten contamination in implantation processes. For some tests, the implanter was contaminated by implantation of wafers with an exposed tungsten layer, resulting in critical contamination conditions. First, DLTS (deep level transient spectroscopy) measurements were calibrated to measure tungsten contamination in ion-implanted samples. DLTS measurements of tungsten-implanted samples showed that the tungsten concentration increases linearly with the dose up to a rather low dose (5 x 10 10 cm -2 ). Tungsten deactivation was observed when the dose was further increased. Under these conditions, ToF-SIMS revealed tungsten at the wafer surface, showing that deactivation was due to surface segregation. DLTS calibration could therefore be obtained in the linear dose regime only. This calibration was used to evaluate the tungsten contamination in arsenic implantations. Ordinary operating conditions and critical contamination conditions of the equipment were compared. A moderate tungsten contamination was observed in samples implanted under ordinary operating conditions. This contamination was easily suppressed by a thin screen oxide. On the contrary, implantations in critical conditions of the equipment resulted in a relevant tungsten contamination, which could be reduced but not suppressed even by a relatively thick screen oxide (up to 150 Aa). A decontamination process consisting of high dose implantations of dummy wafers was tested for its efficiency to remove tungsten and titanium contamination. This process was found to be much more effective for titanium than for tungsten. Finally, DLTS proved to be much more sensitive that TXRF (total reflection X-ray fluorescence) in detecting tungsten contamination. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Detection and reduction of tungsten contamination in ion implantation processes

Energy Technology Data Exchange (ETDEWEB)

Polignano, M.L.; Galbiati, A.; Grasso, S.; Mica, I.; Barbarossa, F.; Magni, D. [STMicroelectronics, Agrate Brianza (Italy)

2016-12-15

In this paper, we review the results of some studies addressing the problem of tungsten contamination in implantation processes. For some tests, the implanter was contaminated by implantation of wafers with an exposed tungsten layer, resulting in critical contamination conditions. First, DLTS (deep level transient spectroscopy) measurements were calibrated to measure tungsten contamination in ion-implanted samples. DLTS measurements of tungsten-implanted samples showed that the tungsten concentration increases linearly with the dose up to a rather low dose (5 x 10{sup 10} cm{sup -2}). Tungsten deactivation was observed when the dose was further increased. Under these conditions, ToF-SIMS revealed tungsten at the wafer surface, showing that deactivation was due to surface segregation. DLTS calibration could therefore be obtained in the linear dose regime only. This calibration was used to evaluate the tungsten contamination in arsenic implantations. Ordinary operating conditions and critical contamination conditions of the equipment were compared. A moderate tungsten contamination was observed in samples implanted under ordinary operating conditions. This contamination was easily suppressed by a thin screen oxide. On the contrary, implantations in critical conditions of the equipment resulted in a relevant tungsten contamination, which could be reduced but not suppressed even by a relatively thick screen oxide (up to 150 Aa). A decontamination process consisting of high dose implantations of dummy wafers was tested for its efficiency to remove tungsten and titanium contamination. This process was found to be much more effective for titanium than for tungsten. Finally, DLTS proved to be much more sensitive that TXRF (total reflection X-ray fluorescence) in detecting tungsten contamination. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Tungsten oxide nanowires grown on amorphous-like tungsten films

International Nuclear Information System (INIS)

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

2015-01-01

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 W_1_8O_4_9-Magneli phase to monoclinic WO_3. 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. (paper)

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology.

Science.gov (United States)

Balliana, Eleonora; Aramendía, Maite; Resano, Martin; Barbante, Carlo; Vanhaecke, Frank

2013-03-01

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ (65)Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ (65)Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic

Tungsten as First Wall Material in Fusion Devices

International Nuclear Information System (INIS)

Kaufmann, M.

2006-01-01

In the PLT tokamak with a tungsten limiter strong cooling of the central plasma was observed. Since then mostly graphite has been used as limiter or target plate material. Only a few tokamaks (limiter: FTU, TEXTOR; divertor: Alcator C-Mod, ASDEX Upgrade) gained experience with high-Z-materials. With the observed strong co- deposition of tritium together with carbon in JET and as a result of design studies of fusion reactors, it became clear that in the long run tungsten is the favourite for the first-wall material. Tungsten as a plasma facing material requires intensive research in all areas, i.e. in plasma physics, plasma wall-interaction and material development. Tungsten as an impurity in the confined plasma reveals considerable differences to carbon. Strong radiation at high temperatures, in connection with mostly a pronounced inward drift forms a particular challenge. Turbulent transport plays a beneficial role in this regard. The inward drift is an additional problem in the pedestal region of H-mode plasmas in ITER-like configurations. The erosion by low energy hydrogen atoms is in contrast to carbon small. However, erosion by fast particles from heating measures and impurity ions, accelerated in the sheath potential, play an important role in the case of tungsten. Radiation by carbon in the plasma boundary reduces the load to the target plates. Neon or Argon as substitutes will increase the erosion of tungsten. So far experiments have demonstrated that in most scenarios the tungsten content in the central plasma can be kept sufficiently small. The material development is directed to the specific needs of existing or future devices. In ASDEX Upgrade, which will soon be a divertor experiment with a complete tungsten first-wall, graphite tiles are coated with tungsten layers. In ITER, the solid tungsten armour of the target plates has to be castellated because of its difference in thermal expansion compared to the cooling structure. In a reactor the technical

Radiative capture of slow electrons by tungsten surface

International Nuclear Information System (INIS)

Artamonov, O.M.; Belkina, G.M.; Samarin, S.N.; Yakovlev, I.I.

1987-01-01

Isochromatic spectra of radiation capture of slow electrons by the surface of mono- and polycrystal tungsten recorded on 322 and 405 nm wave lengths are presented. The effect of oxygen adsorption on isochromates of the (110) face of tungsten monocrystal is investigated. The obtained isochromatic spectra are compared with energy band structure of tungsten. Based on the analysis of the obtained experimental results it is assumed that optical transition to the final state at the energy of 7.3 eV relatively to Fermi level is conditioned by surface states of the tungsten face (110)

Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

Energy Technology Data Exchange (ETDEWEB)

Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

2016-01-01

High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

Human paleodiet and animal utilization strategies during the Bronze Age in northwest Yunnan Province, southwest China.

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Lele Ren

Full Text Available Reconstructing ancient diets and the use of animals and plants augment our understanding of how humans adapted to different environments. Yunnan Province in southwest China is ecologically and environmentally diverse. During the Neolithic and Bronze Age periods, this region was occupied by a variety of local culture groups with diverse subsistence systems and material culture. In this paper, we obtained carbon (δ13C and nitrogen (δ15N isotopic ratios from human and faunal remains in order to reconstruct human paleodiets and strategies for animal exploitation at the Bronze Age site of Shilinggang (ca. 2500 Cal BP in northwest Yunnan Province. The δ13C results for human samples from Shilinggang demonstrate that people's diets were mainly dominated by C3-based foodstuffs, probably due to both direct consumption of C3 food and as a result of C3 foddering of consumed animals. Auxiliary C4 food signals can also be detected. High δ15N values indicate that meat was an important component of the diet. Analysis of faunal samples indicates that people primarily fed pigs and dogs with human food waste, while sheep/goats and cattle were foddered with other food sources. We compare stable isotope and archaeobotanical data from Shilinggang with data from other Bronze Age sites in Yunnan to explore potential regional variation in subsistence strategies. Our work suggests that people adopted different animal utilization and subsistence strategies in different parts of Yunnan during the Bronze Age period, probably as local adaptations to the highly diversified and isolated environments in the region.

Morphology of Si/tungsten-silicides/Si interlayers

International Nuclear Information System (INIS)

Theodore, N.; Secco d'Aragona, F.; Blackstone, S.

1992-01-01

Tungsten and tungsten-silicides are of interest for semiconductor technology because of their refractory nature, low electrical-resistivity and high electromigration-resistance. This paper presents the first formation of buried tungsten-silicide layers in silicon, by proximity adhesion. The interlayers, created by a combination of chemical vapor-deposition (CVD) and proximity-adhesion were studied using transmission electron-microscopy (TEM). The behavior of the layers in the presence and absence of an adjacent silicon-dioxide interlayer was also investigated. Buried silicide layers were successfully formed with or without the adjacent silicon-dioxide. The silicide formed continuous layers with single grains encompassing the width of the interlayer. Individual grains were globular, with cusps at grain boundaries. This caused interlayer-thicknesses to be non-uniform, with lower thickness values being present at the cusps. Occasional voids were observed at grain-boundary cusps. The voids were smaller and less frequent in the presence of an adjacent oxide-layer, due to flow of the oxide during proximity adhesion. Electron-diffraction revealed a predominance of tungsten-disilicide in the interlayers, with some free tungsten being present. Stresses in the silicide layers caused occasional glide dislocations to propagate into the silicon substrate beneath the interlayers. The dislocations propagate only ∼100 nm into the substrate and therefore should not be detrimental to use of the buried layers. Occasional precipitates were observed at the end of glide-loops. These possibly arise due to excess tungsten from the interlayer diffusion down the glide dislocation to finally precipitate out as tungsten-silicide

Surface morphologies of He-implanted tungsten

Energy Technology Data Exchange (ETDEWEB)

Bannister, M.E., E-mail: bannisterme@ornl.gov [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Meyer, F.W.; Hijazi, H. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States); Unocic, K.A.; Garrison, L.M.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2016-09-01

Surface morphologies of tungsten surfaces, both polycrystalline and single-crystal [1 1 0], were investigated using SEM and FIB/SEM techniques after implantations at elevated surfaces temperatures (1200–1300 K) using well-characterized, mono-energetic He ion beams with a wide range of ion energies (218 eV–250 keV). Nanofuzz was observed on polycrystalline tungsten (PCW) following implantation of 100-keV He ions at a flux threshold of 0.9 × 10{sup 16} cm{sup −2} s{sup −1}, but not following 200-keV implantations with similar fluxes. No nanofuzz formation was observed on single-crystal [1 1 0] tungsten (SCW), despite fluxes exceeding those demonstrated previously to produce nanofuzz on polycrystalline tungsten. Pre-damaging the single-crystal tungsten with implanted C impurity interstitials did not significantly affect the surface morphologies resulting from the high-flux He ion implantations. The main factor leading to the different observed surface structures for the pristine and C-implanted single-crystal W samples appeared to be the peak He ion flux characterizing the different exposures. It was speculated that nanofuzz formation was not observed for any SCW target exposures because of increased incubation fluences required for such targets.

The gate oxide integrity of CVD tungsten polycide

International Nuclear Information System (INIS)

Wu, N.W.; Su, W.D.; Chang, S.W.; Tseng, M.F.

1988-01-01

CVD tungsten polycide has been demonstrated as a good gate material in recent very large scale integration (VLSI) technology. CVD tungsten silicide offers advantages of low resistivity, high temperature stability and good step coverage. On the other hand, the polysilicon underlayer preserves most characteristics of the polysilicon gate and acts as a stress buffer layer to absorb part of the thermal stress origin from the large thermal expansion coefficient of tungsten silicide. Nevertheless, the gate oxide of CVD tungsten polycide is less stable or reliable than that of polysilicon gate. In this paper, the gate oxide integrity of CVD tungsten polycide with various thickness combinations and different thermal processes have been analyzed by several electrical measurements including breakdown yield, breakdown fluence, room temperature TDDB, I-V characteristics, electron traps and interface state density

Bronze Jewellery from the Early Iron Age urn-field in Mała Kępa. An approach to casting technology

Directory of Open Access Journals (Sweden)

Garbacz-Klempka A.

2017-09-01

Full Text Available This study characterizes the bronze jewellery recovered from the Lusatian culture urn-field in Mała Kępa (Chełmno land, Poland. Among many common ornaments (e.g. necklaces, rings, pins the ones giving evidence of a steppe-styled inspiration (nail earrings were also identified. With the dendritic microstructures revealed, the nail earrings prove the implementing of a lost-wax casting method, whereas some of the castings were further subjected to metalworking. The elemental composition indicates the application of two main types of bronze alloys: Cu-Sn and Cu-Sn-Pb. It has been established that the Lusatian metalworkers were familiar with re-melting the scrap bronze and made themselves capable of roasting the sulphide-rich ores.

Comparative Investigation of Tungsten Fibre Nets Reinforced Tungsten Composite Fabricated by Three Different Methods

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Linhui Zhang

2017-07-01

Full Text Available Tungsten fibre nets reinforced tungsten composites (Wf/W containing four net layers were fabricated by spark plasma sintering (SPS, hot pressing (HP and cold rolling after HP (HPCR, with the weight fraction of fibres being 17.4%, 10.5% and 10.5%, respectively. The relative density of the HPCRed samples is the highest (99.8% while that of the HPed composites is the lowest (95.1%. Optical and scanning electron microscopy and electron back scattering diffraction were exploited to characterize the microstructure, while tensile and hardness tests were used to evaluate the mechanical properties of the samples. It was found that partial recrystallization of fibres occurred after the sintering at 1800 °C. The SPSed and HPed Wf/W composites begin to exhibit plastic deformation at 600 °C with tensile strength (TS of 536 and 425 MPa and total elongation at break (TE of 11.6% and 23.0%, respectively, while the HPCRed Wf/W composites exhibit plastic deformation at around 400 °C. The TS and TE of the HPCRed Wf/W composites at 400 °C are 784 MPa and 8.4%, respectively. The enhanced mechanical performance of the Wf/W composites over the pure tungsten can be attributed to the necking, cracking, and debonding of the tungsten fibres.

A solid tungsten divertor for ASDEX Upgrade

International Nuclear Information System (INIS)

Herrmann, A; Greuner, H; Jaksic, N; Böswirth, B; Maier, H; Neu, R; Vorbrugg, S

2011-01-01

The conceptual design of a solid tungsten divertor for ASDEX Upgrade (AUG) is presented. The Div-III design is compatible with the existing divertor structure. It re-establishes the energy and heat receiving capability of a graphite divertor and overcomes the limitations of tungsten coatings. In addition, a solid tungsten divertor allows us to investigate erosion and bulk deuterium retention as well as test castellation and target tilting. The design criteria as well as calculations of forces due to halo and eddy currents are presented. The thermal properties of the proposed sandwich structure are calculated with finite element method models. After extensive testing of a target tile in the high heat flux test facility GLADIS, two solid tungsten tiles were installed in AUG for in-situ testing.

The bronze signum from Timacum Maius and its cultic attribution

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Petrović Vladimir

2016-01-01

Full Text Available The bronze signum discussed in this paper was discovered by archaeological ex­cavation on the site of Timacum Maius in 2010. Found in the area of a luxurious Roman-period building, the artefact shows a tapering body with a central conical socket similar to a spearhead socket. It is one of the twenty-three known signa of the so-called classical-type. Most of them were found in the context of the cult of Jupiter Dolichenus, and we also presume the cultic purpose of the bronze signum from Timacum Maius. A similar find comes from Jupiter Dolichenus’ shrine in Egeta on the Danube limes with an inscription that connects it directly with the Dolichenian cult, and with the First Cohort of Cretans (Cohors I Cretum, the unit which had previously been stationed at Timacus Maius. The signum from Timacum Maius is most likely also connected with the cult of Jupiter Dolichenus and chronologically belongs to a period which is much earlier than the Severan age. [Projekat Ministarstva nauke Republike Srbije, 177012: Society, spiritual and material culture and communications in prehistory and early history of the Balkans

Corrosion of high-density sintered tungsten alloys. Part 2

International Nuclear Information System (INIS)

Batten, J.J.; Moore, B.T.

1988-12-01

The behaviour of four high-density sintered tungsten alloys has been evluated and compared with that of pure tungsten. Rates of corrosion during the cyclic humidity and the salt mist tests were ascertained from weight loss measurements. Insight into the corrosion mechanism was gained from the nature of the corrosion products and an examination of the corroded surfaces. In the tests, the alloy 95% W, 2.5% Ni, 1.5% Fe was the most corrosion resistant. The data showed that copper as an alloying element accelerates corrosion of tungsten alloys. Both attack on the tungsten particles and the binder phase were observed together with tungsten grain loss. 6 refs., 3 tabs.,

Substructure and electrical resistivity analyses of pure tungsten sheet

International Nuclear Information System (INIS)

Trybus, C.L.; Sellers, C.H.; Anderl, R.A.

1991-01-01

The substructure of pure tungsten sheet (0.025 mm thick) is examined and quantified by transmission electron microscopy (TEM). Dislocation populations and arrangements are evaluated for as-worked and various annealed conditions of the tungsten sheet. The worked (rolled) tungsten substructure was nonhomogeneous, consisting of areas of very high and low dislocation densities. These results are correlated to resistivity measurements of the tungsten sheet following thermal cycling to 1200 degrees C to determine the substructural changes as a function of temperature. The comparison between the two characterization techniques is used to examine the relationship between structural and electronic properties in tungsten. 15 refs., 6 figs., 2 tabs

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

Synthesis of high purity tungsten nanoparticles from tungsten heavy alloy scrap by selective precipitation and reduction route

International Nuclear Information System (INIS)

Kamal, S.S. Kalyan; Sahoo, P.K.; Vimala, J.; Shanker, B.; Ghosal, P.; Durai, L.

2016-01-01

In this paper we report synthesis of tungsten nanoparticles of high purity >99.7 wt% from heavy alloy scrap using a novel chemical route of selective precipitation and reduction. The effect of Poly(vinylpyrrolidone) polymer on controlling the particle size is established through FTIR spectra and corroborated with TEM images, wherein the average size decreased form 210 to 45 nm with increasing PVP content from zero to 2 g under different experimental conditions. This process is economical as raw material is a scrap and the efficiency of the reaction is >95%. - Highlights: • Tungsten nanoparticles were synthesized from tungsten heavy alloy scrap. • A novel chemical route of precipitation and reduction with Poly(vinylpyrrolidone) polymer as stabilizer is reported. • The average size decreased form 210 to 45 nm with increasing PVP content from zero to 2 g. • High pure tungsten nanoparticles of >99.7% purity could be synthesized using this route. • Efficiency of the reaction is >95%.

Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

International Nuclear Information System (INIS)

Balta, I.Z.; Pederzoli, S.; Iacob, E.; Bersani, M.

2009-01-01

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

Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

Energy Technology Data Exchange (ETDEWEB)

Balta, I.Z., E-mail: balta_z_i@yahoo.com [National Research Institute for Conservation and Restoration, Calea Victoriei 12, Sector 3, 030026 Bucharest (Romania); Pederzoli, S.; Iacob, E.; Bersani, M. [Fondazione Bruno Kessler - IRST, Centro per la Ricerca Scientifica e Tecnologica, Trento (Italy)

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

Female exogamy and gene pool diversification at the transition from the Final Neolithic to the Early Bronze Age in central Europe.

Science.gov (United States)

Knipper, Corina; Mittnik, Alissa; Massy, Ken; Kociumaka, Catharina; Kucukkalipci, Isil; Maus, Michael; Wittenborn, Fabian; Metz, Stephanie E; Staskiewicz, Anja; Krause, Johannes; Stockhammer, Philipp W

2017-09-19

Human mobility has been vigorously debated as a key factor for the spread of bronze technology and profound changes in burial practices as well as material culture in central Europe at the transition from the Neolithic to the Bronze Age. However, the relevance of individual residential changes and their importance among specific age and sex groups are still poorly understood. Here, we present ancient DNA analysis, stable isotope data of oxygen, and radiogenic isotope ratios of strontium for 84 radiocarbon-dated skeletons from seven archaeological sites of the Late Neolithic Bell Beaker Complex and the Early Bronze Age from the Lech River valley in southern Bavaria, Germany. Complete mitochondrial genomes documented a diversification of maternal lineages over time. The isotope ratios disclosed the majority of the females to be nonlocal, while this is the case for only a few males and subadults. Most nonlocal females arrived in the study area as adults, but we do not detect their offspring among the sampled individuals. The striking patterns of patrilocality and female exogamy prevailed over at least 800 y between about 2500 and 1700 BC. The persisting residential rules and even a direct kinship relation across the transition from the Neolithic to the Bronze Age add to the archaeological evidence of continuing traditions from the Bell Beaker Complex to the Early Bronze Age. The results also attest to female mobility as a driving force for regional and supraregional communication and exchange at the dawn of the European metal ages.

Characterization of porous tungsten by microhardness

International Nuclear Information System (INIS)

Selcuk, C.; Wood, J.V.; Morley, N.; Bentham, R.

2001-01-01

One of the applications of tungsten is as high current density dispenser cathode in the form of porous tungsten. It is used as a cathode after being impregnated with an electron emissive material so pore distribution in the part is the most important parameter for its function as a uniform and controlled porosity will lead to a better performance. In this study, application of microhardness as a characterization method for uniformity of the pore distribution and homogeneity of the structure is introduced. Optical microscopy and SEM is used to relate the results and porous tungsten structure for a better understanding of the method applied. (author)

Hydrothermal preparation of blue molybdenum bronze nanoribbons: structural changes in mother crystals, related to solid-state conversion and crystallite splitting to nanomorphology

Science.gov (United States)

Nishida, Takamasa; Eda, Kazuo

2018-02-01

Hydrothermal syntheses of alkali-metal blue molybdenum bronze nanoribbons, which are expected to exhibit unique properties induced by a combined effect of extrinsic and intrinsic low-dimensionalities, from hydrated-alkali-metal molybdenum bronzes were investigated. Nanoribbons grown along the quasi-one-dimensional (1D) conductive direction of Cs0.3MoO3, which is difficult to prepare by the conventional methods, were first synthesized. The nanomorphology formation is achieved by a solid-state conversion (or crystallite splitting) and subsequent crystallite growth, and the structural changes of the starting material related to the conversion were first observed by powder X-ray diffraction and scanning transmission electron microscopy as a result of finely tuned reaction system and preparation conditions. The structural changes were analyzed by model simulations and were attributed to the structural modulations that were concerned with the intralayer packing disorder and with two-dimensional long-range ordered structure, formed in MoO3 sheets of the hydrated molybdenum bronze. Moreover, the modulations were related to displacement defects of the Mo-O framework units generated along the [100] direction in the hydrated molybdenum bronze. Then, it was suggested that the solid-state conversion into blue molybdenum bronze and the crystallite splitting to nanomorphology were initiated by the breaking of the Mo-O-Mo bonds at the defects. [Figure not available: see fulltext.

Microstructure and tensile properties of tungsten at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Shen, Tielong [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Dai, Yong, E-mail: yong.dai@psi.ch [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Lee, Yongjoong [European Spallation Source, Tunavägen 24, 223 63 Lund (Sweden)

2016-01-15

In order to support the development of the 5 MW spallation target for the European Spallation Source, the effect of fabrication process on microstructure, ductile-to-brittle transition temperature (DBTT), tensile and fracture behaviour of powder-metallurgy pure tungsten materials has been investigated. A hot-rolled (HR) tungsten piece of 12 mm thickness and a hot-forged (HF) piece of about 80 mm thickness were used to simulate the thin and thick blocks in the target. The two tungsten pieces were characterized with metallography analysis, hardness measurement and tensile testing. The HR piece exhibits an anisotropic grain structure with an average size of about 330 × 140 × 40 μm in rolling, long transverse and short transverse (thickness) directions. The HF piece possesses a bimodal grain structure with about 310 × 170 × 70 μm grain size in deformed part and about 25 μm sized grains remained from sintering process. Hardness (HV0.2) of the HR piece is slightly greater than that of the HF one. The ductility of the HR tungsten specimens is greater than that of the HF tungsten. For the HF tungsten piece, specimens with small grains in gauge section manifest lower ductility but higher strength. The DBTT evaluated from the tensile results is 250–300 °C for the HR tungsten and about 350 °C for the HF tungsten. - Highlights: • This work was conducted to support the development of the 5 MW spallation target for the European Spallation Source. • The effect of fabrication process on microstructure, ductile-to-brittle transition temperature and tensile behaviour was studied with hot-rolled and hot-forged tungsten. • The tungsten materials were characterized with metallography analysis, hardness measurement and tensile test in a temperature range of 25–500 °C. • The results indicate that the HR tungsten has better mechanical properties in terms of greater ductility and lower ductile-to-brittle transition temperature.

Quenching and recovery experiments on tungsten

International Nuclear Information System (INIS)

Rasch, K.D.; Siegel, R.W.; Schultz, H.

1976-01-01

A short summary is given of new results concerning transmission electron microscopy and resistivity measurements on quenched tungsten. These results give evidence for the first time that the quenching and annealing of high purity tungsten leads to vacancy--defect clustering resulting in small voids observable in the electron microscope. 21 references

Process for separation of tungsten and molybdenum by extraction

International Nuclear Information System (INIS)

Zelikman, A.N.; Voldman, G.M.; Rumyantsev, V.K.; Ziberov, G.N.; Kagermanian, V.S.

1976-01-01

A process for the separation of tungsten and molybdenum by extraction involves the addition of HCl or HNO 3 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

Microstructure investigation of bronze/steel brazed joints proposed for HHF components of ITER manufacturing

Energy Technology Data Exchange (ETDEWEB)

Kalinin, G.M. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation)], E-mail: gmk@nikiet.ru; Krestnikov, N.S. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation); Jarovinskiy, Yu.L.; Makhin, I.D.; Nikolaev, V.V. [Rocket and Space Corporation ' Energia' , Korolev, Lenina Street 4-a, Moscow 141070 (Russian Federation); Skladnov, K.S.; Strebkov, Yu.S.; Zolotarev, V.B. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation)

2008-12-15

Brazing is considered as one of the perspective option of high heat flux components of ITER manufacturing. CuCrZr bronze, austenitic steel AISI 321-type and PM-17-type (Ni-Mn-Fe-Si-Sn-B alloy) brazed material were used for the development of brazing technology. Two type of brazing have been studied within the framework of recent investigation: - Hot isostatic pressing (HIP)-assisted brazing. - Furnace-assisted brazing (with uniaxial compression loading). For the hydrostatic pressing (HIP) the brazed components were pressed out for about 175 MPa during 2.5 h at the temperature 1035-1040 deg. C. For the furnace-assisted brazing all components were inserted into the sealed can, vacuumed and heated up to brazing temperature {approx}950 deg. C. Fast cooling and ageing heat treatment (500 deg. C and 4 h) were applied to provide high strength of CuCrZr bronze. Microsections of specimens cut from the joints were studied by optical microscopy and by scanning electron microscopy (SEM). The microstructure, distribution of alloying elements of base metals and of brazed material components were studied in the joints. Results of these studies are discussed in this paper. The data shows that there is a potential for using more simple and cheap (in comparison with common HIP) technologies of bronze to steel joining with satisfactory quality.

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...

Surface studies of tungsten erosion and deposition in JT-60U

International Nuclear Information System (INIS)

Ueda, Y.; Fukumoto, M.; Nishikawa, M.; Tanabe, T.; Miya, N.; Arai, T.; Masaki, K.; Ishimoto, Y.; Tsuzuki, K.; Asakura, N.

2007-01-01

In order to study tungsten erosion and migration in JT-60U, 13 W tiles have been installed in the outer divertor region and tungsten deposition on graphite tiles was measured. Dense local tungsten deposition was observed on a CFC tile toroidally adjacent to the W tiles, which resulted from prompt ionization and short range migration of tungsten along field lines. Tungsten deposition with relatively high surface density was found on an inner divertor tile around standard inner strike positions and on an outer wing tile of a dome. On the outer wing tile, tungsten deposition was relatively high compared with carbon deposition. In addition, roughly uniform tungsten depth distribution near the upper edge of the inner divertor tile was observed. This could be due to lift-up of strike point positions in selected 25 shots and tungsten flow in the SOL plasma

Tritium Decay Helium-3 Effects in Tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Merrill, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-06-01

A critical challenge for long-term operation of ITER and beyond to a Demonstration reactor (DEMO) and future fusion reactor will be the development of plasma-facing components (PFCs) that demonstrate erosion resistance to steady-state/transient heat fluxes and intense neutral/ion particle fluxes under the extreme fusion nuclear environment, while at the same time minimizing in-vessel tritium inventories and permeation fluxes into the PFC’s coolant. Tritium will diffuse in bulk tungsten at elevated temperatures, and can be trapped in radiation-induced trap site (up to 1 at. % T/W) in tungsten [1,2]. Tritium decay into helium-3 may also play a major role in microstructural evolution (e.g. helium embrittlement) in tungsten due to relatively low helium-4 production (e.g. He/dpa ratio of 0.4-0.7 appm [3]) in tungsten. Tritium-decay helium-3 effect on tungsten is hardly understood, and its database is very limited. Two tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) were exposed to high flux (ion flux of 1.0x1022 m-2s-1 and ion fluence of 1.0x1026 m-2) 0.5%T2/D2 plasma at two different temperatures (200, and 500°C) in Tritium Plasma Experiment (TPE) at Idaho National Laboratory. Tritium implanted samples were stored at ambient temperature in air for more than 3 years to investigate tritium decay helium-3 effect in tungsten. The tritium distributions on plasma-exposed was monitored by a tritium imaging plate technique during storage period [4]. Thermal desorption spectroscopy was performed with a ramp rate of 10°C/min up to 900°C to outgas residual deuterium and tritium but keep helium-3 in tungsten. These helium-3 implanted samples were exposed to deuterium plasma in TPE to investigate helium-3 effect on deuterium behavior in tungsten. The results show that tritium surface concentration in 200°C sample decreased to 30 %, but tritium surface concentration in 500°C sample did not alter over the 3 years storage period, indicating possible tritium

Micro-EDXRF surface analyses of a bronze spear head: Lead content in metal and corrosion layers

International Nuclear Information System (INIS)

Figueiredo, E.; Valerio, P.; Araujo, M.F.; Senna-Martinez, J.C.

2007-01-01

A bronze spear head from Central Portugal dated to Late Bronze Age has been analyzed by non-destructive micro-EDXRF in the metal surface and corrosion layers. The artifact had previously been analyzed using a conventional EDXRF spectrometer having a larger incident beam. The quantification of the micro-EDXRF analyses showed that lead content in corrosion layers can reach values up to four times higher than the content determined in the metal surface. Results obtained with the higher energy incident beam from the EDXRF equipment, although referring mainly to the corrosion layers, seem to suffer some influence from the surface composition of the metallic alloy

Tungsten metallizing alumina--yttria ceramics

International Nuclear Information System (INIS)

Cowan, R.E.; Stoddard, S.D.

1977-03-01

The ease with which high-alumina bodies may be metallized with tungsten is improved by additions of yttria to the alumina. Mechanisms of this bonding process were studied by use of optical and electron microscopy, electron microprobe, and tensile tests. Variables studied included yttria content of the body and the firing temperature during metallizing. The study showed that a reaction between the tungsten and the yttrogarnet grain boundary phase markedly improved adherence

Physical metallurgy of tungsten. Metallovedenie vol'frama

Energy Technology Data Exchange (ETDEWEB)

Savitskii, E M; Povarova, K B; Makarov, P V

1978-01-01

The physico-chemical principles of the interaction between tungsten and the elements of the periodic chart are systematized and summarized, and a description is given of the physical and mechanical properties of tungsten and its alloys. An examination is made of the nature of cold brittleness and methods of increasing the plasticity of alloys, means of producing tungsten, methods of purification, alloying, thermal and mechanical processing, and a survey is made of the contemporary use of tungsten and its alloys in advanced sectors of modern technology. The book is designed for personnel at scientific-research institutes, design bureaus and plants, engaged in the development, technology, and use of alloys of refractory metals as well as for instructors, graduate students and senior students taking metal studies and machine building courses, and aeronautical institutions of higher learning. 431 references, 11 tables.

Selective CVD tungsten on silicon implanted SiO/sub 2/

International Nuclear Information System (INIS)

Hennessy, W.A.; Ghezzo, M.; Wilson, R.H.; Bakhru, H.

1988-01-01

The application range of selective CVD tungsten is extended by its coupling to the ion implantation of insulating materials. This article documents the results of selective CVD tungsten using silicon implanted into SiO/sub 2/ to nucleate the tungsten growth. The role of implant does, energy, and surface preparation in achieving nucleation are described. SEM micrographs are presented to demonstrate the selectivity of this process. Measurements of the tungsten film thickness and sheet resistance are provided for each of the experimental variants corresponding to successful deposition. RBS and XPS analysis are discussed in terms of characterizing the tungsten/oxide interface and to evaluate the role of the silicon implant in the CVD tungsten mechanism. Utilizing this method a desired metallization pattern can be readily defined with lithography and ion implantation, and accurately replicated with a layer of CVD tungsten. This approach avoids problems usually associated with blanket deposition and pattern transfer, which are particularly troublesome for submicron VLSI technology

Combustion of powdery tungsten in pyrotechnic mixtures

International Nuclear Information System (INIS)

Ivanov, G.V.; Reshetov, A.A.; Viktorenko, A.M.; Surkov, V.G.; Karmadonov, L.N.

1982-01-01

The basic regularities of tungsten burning (powder 2-5 μm) with oxidizers most typical for pyrotechnics: nitrates, lead and barium peroxides (powder, 2-8 μm) and potassium perchlorate (powder, 2-8 μm) are studied. Dependences of burning rate as a function of pressure and ratio of components are established. It is supposed that tungsten burning in mixtures with the mentioned nitrates is a complex and multistage process the rate of which is determined by tungsten dissolution in nitrate melts. Analysis of burning products using available methods is complex

An effective approach to synthesize monolayer tungsten disulphide crystals using tungsten halide precursor

International Nuclear Information System (INIS)

Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap; Tanemura, Masaki

2016-01-01

The synthesis of large-area monolayer tungsten disulphide (WS 2 ) single crystal is critical for realistic application in electronic and optical devices. Here, we demonstrate an effective approach to synthesize monolayer WS 2 crystals using tungsten hexachloride (WCl 6 ) as a solid precursor in atmospheric chemical vapor deposition process. In this technique, 0.05M solution of WCl 6 in ethanol was drop-casted on SiO 2 /Si substrate to create an even distribution of the precursor, which was reduced and sulfurized at 750 °C in Ar atmosphere. We observed growth of triangular, star-shaped, as well as dendritic WS 2 crystals on the substrate. The crystal geometry evolves with the shape and size of the nuclei as observed from the dendritic structures. These results show that controlling the initial nucleation and growth process, large WS 2 single crystalline monolayer can be grown using the WCl 6 precursor. Our finding shows an easier and effective approach to grow WS 2 monolayer using tungsten halide solution-casting, rather than evaporating the precursor for gas phase reaction

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.

Tungsten-based composite materials for fusion reactor shields

International Nuclear Information System (INIS)

Greenspan, E.; Karni, Y.

1985-01-01

Composite tungsten-based materials were recently proposed for the heavy constituent of compact fusion reactor shields. These composite materials will enable the incorporation of tungsten - the most efficient nonfissionable inelastic scattering (as well as good neutron absorbing and very good photon attenuating) material - in the shield in a relatively cheap way and without introducing voids (so as to enable minimizing the shield thickness). It is proposed that these goals be achieved by bonding tungsten powder, which is significantly cheaper than high-density tungsten, with a material having the following properties: good shielding ability and relatively low cost and ease of fabrication. The purpose of this work is to study the effectiveness of the composite materials as a function of their composition, and to estimate the economic benefit that might be gained by the use of these materials. Two materials are being considered for the binder: copper, second to tungsten in its shielding ability, and iron (or stainless steel), the common fusion reactor shield heavy constituent

Joining of rubber substrate with bronze surface by the method of molecular adhesion

International Nuclear Information System (INIS)

Oravec, J.; Preto, J.; Hronkovic, J.; Melus, P.; Hirahara, H.; Sang, J.

2017-01-01

During the adhesion process using the adhesives there are many risks of defects caused by boundary stress, strength and to resolve these traditional adhesive problems a method called molecule adhesion technology, was used. This method can successfully adhere different materials and has the advantages such as material independence and strong adhesion strength without any adhesive agent. The impact of selected coupling agents on the green and final adhesion on the boundary bronze surface - natural rubber based coating blend was studied in the presented work. Wires of bronze (Cu/Sn 96:4) coated steel bead wire were submerged in solutions of coupling agents in ethanol for 30 s at various temperature and dried. The effect of the surface modification was evaluated by measuring of XPS, FT-IR, the morphology of the brass plate surfaces after the treatment was studied by the atomic force microscopy (AFM). (authors)

Neutron and X-ray characterisation of the metallurgical properties of a 7th century BC Corinthian-type bronze helmet

Science.gov (United States)

Pantos, E.; Kockelmann, W.; Chapon, L. C.; Lutterotti, L.; Bennet, S. L.; Tobin, M. J.; Mosselmans, J. F. W.; Pradell, T.; Salvado, N.; Butí, S.; Garner, R.; Prag, A. J. N. W.

2005-09-01

Neutron and synchrotron X-ray diffraction, X-ray fluorescence and FTIR were used to examine a Corinthian-type bronze helmet which is now on display at The Manchester Museum, UK. This type of helmet was manufactured out of a single piece of bronze, probably on a rod-anvil, and like all body-armour it was made to measure. Neutron diffraction sampling of the bronze volume in different areas was used to study the composition, microstructure and crystallographic texture of the alloy in order to draw conclusions about the manufacturing processes. The neutron data revealed the presence of microstrains and non-random distributions of bronze grains hinting at annealing-hammering working cycles in order to harden and shape the alloy. X-ray fluorescence showed that the main body of the helmet is a copper-tin alloy, while the noseguard contains zinc in high abundance. This key compositional difference confirms that the noseguard is not the original but is a modern substitute fabricated for restoration purposes. SR XRD and FTIR from several spots on the head and noseguard identified several surface corrosion products and showed a variation of the Cu-Sn or Cu-Zn percentage compositions, and of the mineral phases. Small samples of corrosion flakes extracted from the outside and inside of the helmet were used to obtain powder XRD patterns.

HANDICRAFT IN LATE BRONZE-EARLY IRON AGE IN NAKHCHIVAN

OpenAIRE

Toğrul HALİLOV

2012-01-01

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 grou...

Computer simulations for thorium doped tungsten crystals

International Nuclear Information System (INIS)

Eberhard, Bernd

2009-01-01

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 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 set of Langevin equations, i.e. stochastic

Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

International Nuclear Information System (INIS)

Li Yang; Bao Zhirong; Wu Taotao; Jiang, Junchun; Chen Guantao; Pan Chunxu

2012-01-01

In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.–1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H 2 O and CO 2 gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: ► The stalactitic product was the high purity and good crystallinity malachite. ► Its growth was related to the excess of H 2 O and CO 2 gas concentrations in museum. ► It is harmful to the bronzes, because copper will be consumed from the matrix. ► The suggestions for preservation of the similar bronzes in museum were proposed.

Tungsten deposition by hydrogen-atom reaction with tungsten hexafluoride

International Nuclear Information System (INIS)

Lee, W.W.

1991-01-01

Using gaseous hydrogen atoms with WF 6 , tungsten atoms can be produced in a gas-phase reaction. The atoms then deposit in a near-room temperature process, which results in the formation of tungsten films. The W atoms (10 10 -10 11 /cm 3 ) were measured in situ by atomic absorption spectroscopy during the CVD process. Deposited W films were characterized by Auger electron spectroscopy, Rutherford backscattering, and X-ray diffraction. The surface morphology of the deposited films and filled holes was studied using scanning electron microscopy. The deposited films were highly adherent to different substrates, such as Si, SiO 2 , Ti/Si, TiN/Si and Teflon. The reaction mechanism and kinetics were studied. The experimental results indicated that this method has three advantages compared to conventional CVD or PECVD: (1) film growth occurs at low temperatures; (2) deposition takes place in a plasma-free environment; and (3) a low level of impurities results in high-quality adherent films

Modeling of hydrogen desorption from tungsten surface

Energy Technology Data Exchange (ETDEWEB)

Guterl, J., E-mail: jguterl@ucsd.edu [University of California, San Diego, La Jolla, CA 92093 (United States); Smirnov, R.D. [University of California, San Diego, La Jolla, CA 92093 (United States); Krasheninnikov, S.I. [University of California, San Diego, La Jolla, CA 92093 (United States); Nuclear Research National University MEPhI, Moscow 115409 (Russian Federation); Uberuaga, B.; Voter, A.F.; Perez, D. [Los Alamos National Laboratory, Los Alamos, NM 8754 (United States)

2015-08-15

Hydrogen retention in metallic plasma-facing components is among key-issues for future fusion devices. For tungsten, which has been chosen as divertor material in ITER, hydrogen desorption parameters experimentally measured for fusion-related conditions show large discrepancies. In this paper, we therefore investigate hydrogen recombination and desorption on tungsten surfaces using molecular dynamics simulations and accelerated molecular dynamics simulations to analyze adsorption states, diffusion, hydrogen recombination into molecules, and clustering of hydrogen on tungsten surfaces. The quality of tungsten hydrogen interatomic potential is discussed in the light of MD simulations results, showing that three body interactions in current interatomic potential do not allow to reproduce hydrogen molecular recombination and desorption. Effects of surface hydrogen clustering on hydrogen desorption are analyzed by introducing a kinetic model describing the competition between surface diffusion, clustering and recombination. Different desorption regimes are identified and reproduce some aspects of desorption regimes experimentally observed.

Performance and impedance studies of thin, porous molybdenum and tungsten electrodes for the alkali metal thermoelectric converter

Science.gov (United States)

Wheeler, B. L.; Williams, R. M.; Jeffries-Nakamura, B.; Lamb, J. L.; Loveland, M. E.; Bankston, C. P.; Cole, T.

1988-01-01

Columnar, porous, magnetron-sputtered molybdenum and tungsten films show optimum performance as alkali metal thermoelectric converter electrodes at thicknesses less than 1.0 micron when used with molybdenum or nickel current collector grids. Power densities of 0.40 W/sq cm for 0.5-micron molybdenum films at 1200 K and 0.35 W/sq cm for 0.5-micron tungsten films at 1180 K were obtained at electrode maturity after 40-90 h. Sheet resistances of magnetron sputter deposited films on sodium beta-double-prime-alumina solid electrolyte (BASE) substrates were found to increase very steeply as thickness is decreased below about 0.3-double-prime 0.4-micron. The ac impedance data for these electrodes have been interpreted in terms of contributions from the bulk BASE and the porous electrode/BASE interface. Voltage profiles of operating electrodes show that the total electrode area, of electrodes with thickness less than 2.0 microns, is not utilized efficiently unless a fairly fine (about 1 x 1 mm) current collector grid is employed.

Chipped Stone Industry of the Moravian Early Bronze Age – Typological Considerations

Czech Academy of Sciences Publication Activity Database

Kopacz, J.; Matějka, František; Matějková, Jiřina; Přichystal, A.; Škrdla, Petr; Šebela, Lubomír

2006-01-01

Roč. 2, - (2006), s. 95-117. ISBN 80-7248-395-1. ISSN N R&D Projects: GA AV ČR(CZ) IAA8001202 Institutional research plan: CEZ:AV0Z80010507; CEZ:AV0Z20650511 Keywords : Early Bronze Age * Moravia * stone chipped industry, segment Subject RIV: AC - Archeology, Anthropology, Ethnology

Structure and phase transformation behavior of electroless Ni-P alloys containing tin and tungsten

International Nuclear Information System (INIS)

Balaraju, J.N.; Jahan, S. Millath; Jain, Anjana; Rajam, K.S.

2007-01-01

Autocatalytic ternary Ni-Sn-P, Ni-W-P and quaternary Ni-W-Sn-P films were prepared using alkaline citrate-based baths and compared with binary Ni-P coatings. Energy dispersive analysis of X-ray (EDAX) showed that binary Ni-P deposit contained 11.3 wt.% of phosphorus. Codeposition of tungsten in Ni-P matrix resulted in ternary Ni-W-P with 5 wt.% P and 7.8 wt.% of tungsten. Incorporation of tin led to ternary Ni-Sn-P deposit containing 0.4 wt.% Sn and 10.3 wt.% P. Presence of both sodium tungstate and sodium stannate in the basic bath had resulted in quaternary coating with 6.9 wt.% W, traces of Sn and 6.4 wt.% P. X-ray diffraction patterns of all the deposits revealed a single, broad peak which showed the nanocrystalline nature of the deposits. For the first time in related literature, the presence of a metastable phase Ni 12 P 5 in ternary deposits is reported in the present study. Metallographic cross-sections of all the deposits revealed the banded/lamellar structure. Scanning electron microscopy (SEM) studies of the deposits showed smooth nodules for ternary deposits, but coarse and well-defined nodules for quaternary deposits. DSC studies of phase transformation behavior of the ternary Ni-Sn-P deposit revealed a single sharp exothermic peak at 365 o C. However, ternary Ni-W-P and quaternary Ni-W-Sn-P deposits exhibited a low temperature peak at 300 o C, a split type high temperature peak at 405 and 440 o C and a very high temperature peak at 550 o C. Higher activation energy values were obtained for W-based alloy deposits. Presence of W and Sn has helped to retain high microhardness values even at higher temperatures indicating an improved thermal stability

Substitution of thoriated tungsten electrodes in Switzerland

International Nuclear Information System (INIS)

Kunz, H.; Piller, G.

2006-01-01

Thoriated tungsten electrodes are frequently used for inert gas welding (TIG/WIG). The use of these electrodes can lead to doses which are well above the limit for the general population (1mSv/year). This has been shown by different investigations, for example from the ''Berufsgenossenschaft''. With these findings in mind, the regulatory authorities (Swiss Federal Office of Public Health (SFOPH) and Swiss National Accident Insurance Association (Suva)) started in 1999 to examine the justification of thoriated tungsten electrodes and a possible substitution with products containing no radioactive material. Up to this time, the use of thoriated tungsten electrodes could be justified since no thorium-free products leading to comparable results were available on the market. This was also the reason why the SFOPH approved several types of these electrodes. Discussions with formation centers for welding and inquiries made at welding shops, trading companies and producers showed that in the mean-time thorium-free products with comparable welding specifications and results became available on the market. Since the 1 January 2004, thoriated tungsten electrodes can only be used if the user has obtained the corresponding license from the SFOPH. The use of thoriated tungsten electrodes is thus not completely forbidden, but very strict conditions have to be fulfilled. Up to now and due to the involvement of the relevant partners, the substitution process has not met any problem. Neither trading companies nor users made any opposition and no request for obtaining a license for thoriated tungsten electrodes was made. (orig.)

Effect of neutron irradiation on the microstructure of tungsten

Directory of Open Access Journals (Sweden)

M. Klimenkov

2016-12-01

Full Text Available Two grades of pure tungsten, single and polycrystalline, were irradiated for 282 days in the HFR reactor, Petten, at 900 °C to an average damage level of 1.6dpa. Each grade of tungsten was investigated using the transmission electron microscope (TEM to assess the effect of neutron irradiation on tungsten microstructure. Investigations revealed the formation of faceted cavities, whose diameter varies from 4 to 14nm in both materials. The cavities are homogeneously distributed only inside single crystalline tungsten. The local distribution of cavities in polycrystalline tungsten is strongly influenced by grain boundaries. The number densities of cavities were measured to be 4×1021 m−3 for polycrystalline and 2.5×1021 m−3 for single crystalline tungsten. This corresponds to volumetric densities of 0.45% and 0.33% respectively. High-resolution transmission electron microscopy (HRTEM revealed that faces of cavities are oriented in (110 plane. Analytical investigations showed precipitation of rhenium and osmium produced by a transmutation reaction around cavities and at grain boundaries.

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

International Nuclear Information System (INIS)

Chatzikyriakou, Dafni; Krins, Natacha; Gilbert, Bernard; Colson, Pierre; Dewalque, Jennifer; Denayer, Jessica; Cloots, Rudi; Henrist, Catherine

2014-01-01

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 WO 3 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 Li x WO 3 bronze

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

Energy Technology Data Exchange (ETDEWEB)

Torrisi, L., E-mail: Lorenzo.Torrisi@unime.it [Department of Physics Science - MIFT, Messina University, V.le F.S. d’Alcontres 31, 98166 S. Agata, Messina (Italy); Italiano, A. [INFN, Sezione di Catania, Gruppo collegato di Messina (Italy); Torrisi, A. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland)

2016-11-30

Highlights: • Surface and bulk compositional elements in ancient bronze coins were investigated using XRF analysis. • Lead stable isotope {sup 204}Pb, {sup 206}Pb, {sup 207}Pb and {sup 208}Pb were measured in ancient coins with LAMQS analysis. • Lead ratios {sup 208}Pb/{sup 206}Pb and {sup 207}Pb/{sup 206}Pb, measured by LAMQS, were compared with Brettscaife.net geological database relative to the minerals in different mines of Mediterranean basin. • Bronze coins were correlated to possible ancient mining sites of minerals from which lead was extracted. - Abstract: 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 {sup 208}Pb/{sup 206}Pb and {sup 207}Pb/{sup 206}Pb 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.

Investigation of laser cleaning on bronze cultural relics

International Nuclear Information System (INIS)

Ling, Xiulan; Wang, Gao; Zhang, Chen

2016-01-01

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. (paper)

Vaporization of tungsten-metal in steam at high temperatures

International Nuclear Information System (INIS)

Greene, G.A.; Finfrock, C.C.

2000-01-01

The vaporization of tungsten from the APT spallation target dominates the radiological source term for unmitigated target overheating accidents. Chemical reactions of tungsten with steam which persist to tungsten temperatures as low as 800 C result in the formation of a hydrated tungsten-oxide which has a high vapor pressure and is readily convected in a flowing atmosphere. This low-temperature vaporization reaction essentially removes the oxide film that forms on the tungsten-metal surface as soon as it forms, leaving behind a fresh metallic surface for continued oxidation and vaporization. Experiments were conducted to measure the oxidative vaporization rates of tungsten in steam as part of the effort to quantify the MT radiological source term for severe target accidents. Tests were conducted with tungsten rods (1/8 inch diameter, six inches long) heated to temperatures from approximately 700 C to 1350 C in flowing steam which was superheated to 140 C. A total of 19 experiments was conducted. Fifteen tests were conducted by RF induction heating of single tungsten rods held vertical in a quartz glass retort. Four tests were conducted in a vertically-mounted tube furnace for the low temperature range of the test series. The aerosol which was generated and transported downstream from the tungsten rods was collected by passing the discharged steam through a condenser. This procedure insured total collection of the steam along with the aerosol from the vaporization of the rods. The results of these experiments revealed a threshold temperature for tungsten vaporization in steam. For the two tests at the lowest temperatures which were tested, approximately 700 C, the tungsten rods were observed to oxidize without vaporization. The remainder of the tests was conducted over the temperature range of 800 C to 1350 C. In these tests, the rods were found to have lost weight due to vaporization of the tungsten and the missing weight was collected in the downstream condensate

Fabrication and evaluation of chemically vapor deposited tungsten heat pipe.

Science.gov (United States)

Bacigalupi, R. J.

1972-01-01

A network of lithium-filled tungsten heat pipes is being considered as a method of heat extraction from high temperature nuclear reactors. The need for material purity and shape versatility in these applications dictates the use of chemically vapor deposited (CVD) tungsten. Adaptability of CVD tungsten to complex heat pipe designs is shown. Deposition and welding techniques are described. Operation of two lithium-filled CVD tungsten heat pipes above 1800 K is discussed.

Comparison of four tungsten alloys for use as ultrasonic thermometer sensors

International Nuclear Information System (INIS)

Arave, A.E.

1975-06-01

Four tungsten alloy materials were evaluated for use as ultrasonic sensors: (a) tungsten, (b) tungsten-1 percent thoria, (c) tungsten-2 percent thoria, and (d) tungsten-26 percent rhenium. Four parameters were checked: (1) temperature sensitivity, (2) signal attenuation as a function of temperature, (3) temperature sensitivity as a function of frequency, and (4) relative signal attenuation as a function of frequency. The temperature sensors were designed for the Loss-of-Fluid Test (LOFT) and Power Burst Facility (PBF) reactors. (U.S.)

Adhesion of non-selective CVD tungsten to silicon dioxide

International Nuclear Information System (INIS)

Woodruff, D.W.; Wilson, R.H.; Sanchez-Martinez, R.A.

1986-01-01

Adhesion of non-selective, CVD tungsten to silicon dioxide is a critical issue in the development of tungsten as a metalization for VLSI circuitry. Without special adhesion promoters, tungsten deposited from WF/sub 6/ and H/sub 2/ has typically failed a standard tape test over all types of silicon oxides and nitrides. The reasons for failure of thin films, and CVD tungsten in particular are explored along with standard techniques for improving adhesion of thin films. Experiments are reported which include a number of sputtered metals as adhesion promoters, as well as chemical and plasma treatment of the oxide surface. Sputtered molybdenum is clearly the superior adhesion promoting layer from these tests. Traditional adhesion layers such as chromium or titanium failed as adhesion layers for CVD tungsten possibly due to chemical reactions between the WF/sub 6/ and Cr or Ti

New doped tungsten cathodes. Applications to power grid tubes

International Nuclear Information System (INIS)

Cachard, J. de; Cadoret, K; Martinez, L.; Veillet, D.; Millot, F.

2001-01-01

Thermionic emission behavior of tungsten/tungsten carbide modified with rare earth (La, Ce, Y) oxides is examined on account of suitability to deliver important current densities in a thermo-emissive set up and for long lifetime. Work functions of potential cathodes have been determined from Richardson plots for La 2 O 3 doped tungsten and for tungsten covered with variable compositions rare earth tungstates. The role of platinum layers covering the cathode was also examined. Given all cathodes containing mainly lanthanum oxides were good emitters, emphasis was put on service lifetime. Comparisons of lifetime in tungsten doped with rare earth oxides and with rare earth tungstates show that microstructure of the operating cathodes may play the major role in the research of very long lifetime cathodes. Based on these results, tests still running show lifetime compatible with power grid tubes applications. (author)

Deuterium transport and trapping in polycrystalline tungsten

International Nuclear Information System (INIS)

Anderl, R.A.; Holland, D.F.; Longhurst, G.R.; Pawelko, R.J.; Trybus, C.L.; Sellers, C.H.

1992-01-01

This paper reports that deuterium permeation studies for polycrystalline tungsten foil have been conducted to provide data for estimating tritium transport and trapping in tungsten-clad divertors proposed for advanced fusion-reactor concepts. Based on a detailed transmission electron microscopy (TEM) microstructural characterization of the specimen material and on analyses of permeation data measured at temperatures ranging form 610 to 823 K for unannealed and annealed tungsten foil (25 μm thick), the authors note the following key results: deuterium transport in tungsten foil is dominated by extensive trapping that varies inversely with prior anneal temperatures of the foil material, the reduction in the trapped fraction correlates with a corresponding elimination of a high density of dislocations in cell-wall structures introduced during the foil fabrication process, trapping behavior in these foils can be modelled using trap energies between 1.3 eV and 1.5 eV and trap densities ranging from 1 x 10 -5 atom fraction

A New Chronology for the Bronze Age of Northeastern Thailand and Its Implications for Southeast Asian Prehistory.

Science.gov (United States)

Higham, Charles F W; Douka, Katerina; Higham, Thomas F G

2015-01-01

There are two models for the origins and timing of the Bronze Age in Southeast Asia. The first centres on the sites of Ban Chiang and Non Nok Tha in Northeast Thailand. It places the first evidence for bronze technology in about 2000 B.C., and identifies the origin by means of direct contact with specialists of the Seima Turbino metallurgical tradition of Central Eurasia. The second is based on the site of Ban Non Wat, 280 km southwest of Ban Chiang, where extensive radiocarbon dating places the transition into the Bronze Age in the 11th century B.C. with likely origins in a southward expansion of technological expertise rooted in the early states of the Yellow and Yangtze valleys, China. We have redated Ban Chiang and Non Nok Tha, as well as the sites of Ban Na Di and Ban Lum Khao, and here present 105 radiocarbon determinations that strongly support the latter model. The statistical analysis of the results using a Bayesian approach allows us to examine the data at a regional level, elucidate the timing of arrival of copper base technology in Southeast Asia and consider its social impact.

Incorporation of tungsten metal fibers in a metal and ceramic matrix

Directory of Open Access Journals (Sweden)

V. Brozek

2017-01-01

Full Text Available Tungsten fibers have high tensile strength but a poor oxidation resistance at elevated temperatures. Using this first characteristic and to prevent oxidation of tungsten coated composite materials in which the primary requirement: reinforcement against destruction or deformation, was studied on tungsten fibers and tungsten wires which were coated by applying the metal and ceramic powders via plasma spraying device in plasma generator WSP®. Deposition took place in an atmosphere of Ar + 7 % H2, sufficient to reduce the oxidized trace amounts of tungsten.

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

An effective approach to synthesize monolayer tungsten disulphide crystals using tungsten halide precursor

Energy Technology Data Exchange (ETDEWEB)

Thangaraja, Amutha; Shinde, Sachin M.; Kalita, Golap, E-mail: kalita.golap@nitech.ac.jp; Tanemura, Masaki [Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

2016-02-01

The synthesis of large-area monolayer tungsten disulphide (WS{sub 2}) single crystal is critical for realistic application in electronic and optical devices. Here, we demonstrate an effective approach to synthesize monolayer WS{sub 2} crystals using tungsten hexachloride (WCl{sub 6}) as a solid precursor in atmospheric chemical vapor deposition process. In this technique, 0.05M solution of WCl{sub 6} in ethanol was drop-casted on SiO{sub 2}/Si substrate to create an even distribution of the precursor, which was reduced and sulfurized at 750 °C in Ar atmosphere. We observed growth of triangular, star-shaped, as well as dendritic WS{sub 2} crystals on the substrate. The crystal geometry evolves with the shape and size of the nuclei as observed from the dendritic structures. These results show that controlling the initial nucleation and growth process, large WS{sub 2} single crystalline monolayer can be grown using the WCl{sub 6} precursor. Our finding shows an easier and effective approach to grow WS{sub 2} monolayer using tungsten halide solution-casting, rather than evaporating the precursor for gas phase reaction.

Ab initio and DFT benchmarking of tungsten nanoclusters and tungsten hydrides

International Nuclear Information System (INIS)

Skoviera, J.; Novotny, M.; Cernusak, I.; Oda, T.; Louis, F.

2015-01-01

We present several benchmark calculations comparing wave-function based methods and density functional theory for model systems containing tungsten. They include W 4 cluster as well as W 2 , WH and WH 2 molecules. (authors)

Gleeble Testing of Tungsten Samples

Science.gov (United States)

2013-02-01

temperature on an Instron load frame with a 222.41 kN (50 kip) load cell . The samples were compressed at the same strain rate as on the Gleeble...ID % RE Initial Density (cm 3 ) Density after Compression (cm 3 ) % Change in Density Test Temperature NT1 0 18.08 18.27 1.06 1000 NT3 0...4.1 Nano-Tungsten The results for the compression of the nano-tungsten samples are shown in tables 2 and 3 and figure 5. During testing, sample NT1

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.

Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

Energy Technology Data Exchange (ETDEWEB)

Li Yang; Bao Zhirong; Wu Taotao [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Jiang, Junchun [Xiaogan Museum, Xiaogan 432000 (China); Chen Guantao [Center for Archaeometry, Wuhan University, Wuhan 430072 (China); Pan Chunxu, E-mail: cxpan@whu.edu.cn [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Center for Archaeometry, Wuhan University, Wuhan 430072 (China)

2012-06-15

In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.-1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H{sub 2}O and CO{sub 2} gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: Black-Right-Pointing-Pointer The stalactitic product was the high purity and good crystallinity malachite. Black-Right-Pointing-Pointer Its growth was related to the excess of H{sub 2}O and CO{sub 2} gas concentrations in museum. Black-Right-Pointing-Pointer It is harmful to the bronzes, because copper will be consumed from the matrix. Black-Right-Pointing-Pointer The suggestions for preservation of the similar bronzes in museum were proposed.

In-situ field-ion microscope study of the recovery behavior of heavy metal ion-irradiated tungsten, tungsten (rhenium) alloys and molybdenum

International Nuclear Information System (INIS)

Nielsen, C.H.

1977-06-01

Three field ion microscope (FIM) experiments were carried out to study the annealing behavior of heavy ion irradiated tungsten, tungsten (rhenium) alloys and molybdenum. The first experiment dealt with the stage I long-range migration of tungsten self interstitial atoms (SIAs) in high purity tungsten of resistivity ratio, R = 24,000 (R = rho 300 /rho 4 . 2 , where rho 300 and rho 4 . 2 are the room temperature and 0 0 C resistivities). The FIM specimens were irradiated in situ at 18 K with 30 keV W + ions to an average dose of 5 x 10 12 ions cm -2 and subsequently examined by the pulsed-field evaporation technique. The second experiment dealt with the phenomenon of impurity atom trapping of SIAs during long-range migration. It was shown that rhenium atoms in a tungsten matrix tend to capture tungsten SIAs and remain bound up to temperatures as high as 390 K. The final experiment was concerned with the low temperature annealing kinetics of irradiated molybdenum. High purity molybdenum of resistivity ratio R = 5700 was irradiated at 10 K with 30 keV Mo + ions to a dose of approximately 5 x 10 12 ions cm -2 . The results indicated that the electric field has only a minimal effect on the SIA annealing kinetics. This tends to strengthen the contention that the molybdenum SIA becomes mobile at 32 K

Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and micro-structure of the bronze CuAl10Ni5Fe4

Directory of Open Access Journals (Sweden)

B. Pisarek

2010-04-01

Full Text Available Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the quantity the slag rafining - covering Unitop BA-1 (0÷1,5% on the effectiveness of the protection of liquid bronze before the oxygenation, the quantity of the preliminary alloy - in-oculant AlBe5 (0÷1,0% on the effective compensation melting loss of aluminum and time of isothermal holding on the effect of the in-oculation of the bronze and the comparison of the effectiveness of the inoculation of the bronze in furnace and in the form. Introduced investigations resulted from the study of the new grades of the Cu-Al-Fe-Ni bronze with additions singly or simultaneously Si, Cr, Mo and/or W, to melting which necessary it is for high temperature and comparatively long time isothermal holding indispensable to the occur of the process of diffusive dissolving the high-melting of the bronze components. High temperature and lengthening the time of isothermal holding the liquid bronze in casting furnace the melting loss of Al influences the growth. Addition the slag of covering-refining Unitop BA-1 in the quantity 1,5% the bronze protects before the melting loss of aluminum by the time of isothermal holding in the temperature 1300°C about 15 minutes. Addition of the preliminary alloy AlBe5 in the quantity 0,6% it assures the effective compensation of the aluminum which melting loss undergoes for the studied parameters of the melting. The effect of the inoculation of the bronze together with diminishes the preliminary alloy AlBe5 with lengthening the time of isothermal hold-ing. Because of this, use of the method of introducing the preliminary alloy it is seems good solution on the inoculation of aluminum bronzes directly to form, unsensitive on the time of isothermal holding the bronze.

Formation of carbon containing layers on tungsten test limiters

International Nuclear Information System (INIS)

Rubel, M.; Philipps, V.; Huber, A.; Tanabe, T.

1999-01-01

Tungsten test limiters of mushroom shape and a plasma facing area of approximately 100 cm 2 were exposed at the TEXTOR-94 tokamak to a number of deuterium fuelled discharges performed under various operation conditions. Two types of limiters were tested: a sole tungsten limiter and a twin limiter consisting of two halves, one made of tungsten and another of graphite. The exposed surfaces were examined with ion beam analysis methods and laser profilometry. The formation of some deposition zones was observed near the edges of the limiters. The deuterium-to-carbon concentration ratio was in the range from 0.04 to 0.11 and around 0.2 for the sole tungsten and the twin limiter, respectively. Significant amounts of the co-deposited tungsten and silicon atoms were found on the graphite part of the twin limiter indicating the formation of mixed W-C-Si compounds. (orig.)

Stabilized superconductors

International Nuclear Information System (INIS)

Wong, J.

1975-01-01

The stable, high field, high current composite wire comprises multiple filaments in a depleted bronze matrix, each filament comprising a type II superconducting, beta-tungsten structure, intermetallic compound layer jacketing and metallurgically bonded to a stabilizing copper core, directly or via an intermediate layer of refractory metal

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.

Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Tian, Y.H. (Academia Sinica, Lanzhou, Gansu (China). Inst. of Modern Physics); Pepelnik, R.; Fanger, H.U. (GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht-Tesperhude (Germany, F.R.). Inst. fuer Physik)

1990-01-01

Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state {sup 207m}Pb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for {gamma}-ray self-absorption in the samples and summing of coincident {gamma}-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.).

Development of Cu-Be bronzes through powder metallurgy

International Nuclear Information System (INIS)

Abbas, M.

2012-01-01

Copper and copper alloys are the major group of commercial alloy. One of the important copper bronzes is Copper beryllium. This is unique among all engineering alloys. Copper beryllium alloy possesses the highest strength in all the copper base alloys. Development of copper beryllium alloy with powder metallurgy is challenging problem due to toxicity of beryllium dust. Purpose of this project to find out parameters by which copper beryllium with all unique properties should obtained. For this purpose efforts are put on development of alternative to copper beryllium system like copper-tin and copper-aluminum by powder metallurgy route. Different time of milling with uniaxial pressure of about 200 MPa and different sintering temperature according to phase diagram of alloy, with different soaking time is tried. Problems may occur like decrease in density after sintering, breaking of samples by Rockwell A, B and C indenters arid by hammering. Cold iso-static pressing at 300 MPa and sintering at above 900 degree C is used to develop copper beryllium alloy. As quenched samples are heat treated at 260 degree C, 315 degree C and 370 degree C with different soaking time of 30, 90 and 180 minutes to find out optimum time and temperature parameters. . It is observed that at aging at 260 degree C for 180 minutes, aging at 315 degree C for 180 minutes and aging at 370 degree C for 30 minutes produce optimum result. By observing these pellets by SEM, precipitates appeared in peak-aged alloy and bigger precipitates in over-aged alloy. Copper beryllium alloy developed through powder metallurgy has better prospects than other copper bronzes. (author)

Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition

International Nuclear Information System (INIS)

Sharma, Uttam; Chauhan, Sachin S; Sharma, Jayshree; Sanyasi, A K; Ghosh, J; Choudhary, K K; Ghosh, S K

2016-01-01

The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m 2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS. (paper)

Recovery of Tungsten and Molybdenum from Low-Grade Scheelite

Science.gov (United States)

Li, Yongli; Yang, Jinhong; Zhao, Zhongwei

2017-10-01

With most high-quality tungsten ores being exhausted, the enhancement of low-grade scheelite concentrates processing has attracted a great deal of attention. The objective of this study is to develop a method to maximize the recovery tungsten and molybdenum from a low-grade scheelite via a new acid leaching process followed by solvent extraction. Under optimal conditions (350 g/L H2SO4, 95°C, and 2 h), approximately 99.8% of tungsten and 98% of molybdenum were leached out. In the subsequent solvent extraction process, more than 99% of the tungsten and molybdenum were extracted with a co-extraction system (50% TBP, 30% HDEHP, and 10% 2-octanol in kerosene) using a three-stage cross-flow extraction. The raffinate can be recycled for the next leaching process after replenishing the H2SO4 to the initial value (approximately 350 g/L). Based on these results, a conceptual flowsheet is presented to recover tungsten and molybdenum from the low-grade scheelite.

Tungsten and refractory metals 3, proceedings

International Nuclear Information System (INIS)

Bose, A.; Dowding, R.J.

1996-01-01

The Third International Conference on Tungsten and Refractory Metals was held in Greater Washington DC at the McLean Hilton, McLean Virginia, on November 15--16, 1995. This meeting was the third in a series of conferences held in the Washington DC area. The first meeting was in 1992 and was entitled ''International Conference on Tungsten and Tungsten Alloys.'' In 1994, the scope of the meeting was expanded to include other refractory metals such as molybdenum, iridium, rhenium, tantalum and niobium. The tremendous success of that meeting was the primary motivation for this Conference. The broader scope (the inclusion of other refractory metals and alloys) of the Conference was kept intact for this meeting. In fact, it was felt that the developments in the technology of these materials required a common forum for the interchange of current research information. The papers presented in this meeting examined the rapid advancements in the technology of refractory metals, with special emphasis on the processing, structure, and properties. Among the properties there was emphasis on both quasi-static and dynamic rates. Another topic that received considerable interest was the area of refractory carbides and tungsten-copper composites. One day of concurrent session was necessary to accommodate all of the presentations

Electrospark doping of steel with tungsten

International Nuclear Information System (INIS)

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

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.

Sequestration and Storage of Uranium atom using polyoxotungstates: Synthesis of polytungstodioxouranate(V I)

International Nuclear Information System (INIS)

Mohadeszadeh, M.; Alizadeh, M. H.

2008-01-01

The knowledge of uranium and its waste products behavior in environment is of great concern for many scientists ill several different research fields. The high thermal stability and radiation-resistant natures of polyoxometalates in particular, attract attention to use of these species for the separation and sequestration of radioactive wastes. Reaction of [XW 9 O 33 , 34 ] n- anions with lanthanide and actinide cations which demand coordination numbers greater than six, yields a variety of polyoxoanions with unanticipated stoichiometries and structures [3, 4]. We report the syntheses of the first uranyl-containing polyrungstates with As(III) as the hetero atom that is formed by the reaction of a neutralized (p H 7-7.5) solution of WO 4 2- and As 2 O 3 with an UO 2 2+ solution in a stoichiometric ratio. We have synthesized the sodium salt [As 2 W 18 U 2 O 70 ] 14 and characterized by elemental analysis, IR, UV spectroscopies and elemental analysis. The sodium salt contain two UO 2 2+ sandwiched between two [AsW 9 O 33 ] 9- groups. The formation of this complex suggests the possibility of thermal conversion to uranium-rich tungsten bronzes for radioactive waste storage

Analysis of the Causes of Cracks in a Thick-Walled Bush Made of Die-Cast Aluminum Bronze

Directory of Open Access Journals (Sweden)

Pisarek B.P.

2016-12-01

Full Text Available For the die casting conditions of aluminium bronzes assumed based on the literature data, a thick-walled bush was cast, made of complex aluminium bronze (Cu-Al-Fe-Ni-Cr. After the cast was removed from the mould, cracks were observed inside it. In order to identify the stage in the technological production process at which, potentially, the formation of stresses damaging the continuity of the microstructure created in the cast was possible (hot cracking and/or cold cracking, a computer simulation was performed. The article presents the results of the computer simulation of the process of casting the material into the gravity die as well as solidifying and cooling of the cast in the shape of a thick-walled bush. The simulation was performed with the use of the MAGMA5 program and by application of the CuAl10Ni5,5Fe4,5 alloy from the MAGMA5 program database. The results were compared with the location of the defects identified in the actual cast. As a result of the simulation of the die-casting process of this bush, potential regions were identified where significant principal stresses accumulate, which can cause local hot and cold cracking. Until now, no research has been made of die-cast aluminium bronzes with a Cr addition. Correlating the results of the computer simulation validated by the analysis of the actual cast made it possible to clearly determine the critical regions in the cast exposed to cracking and point to the causes of its occurrence. Proposals of changes in the bush die casting process were elaborated, in order to avoid hot tearing and cold cracking. The article discusses the results of preliminary tests being a prologue to the optimization of the die-casting process parameters of complex aluminium bronze thick-walled bushs.

Bronze analysis by k0-NAA and PIXE

International Nuclear Information System (INIS)

Arana, G.; Waetjen, U.; Ingelbrecht, C.; Robouch, P.

2003-01-01

Five copper alloys were prepared with modern powder metallurgical processes in the frame of the European project 'Improvement of Means of Measurement on Archaeological Copper-Alloys for Characterisation and Conservation (IMMACO)' and certified for As, Pb, Sn and Zn mass fractions. Similar in their composition to archaeological bronze alloys, these Certified Reference Materials (CRMs) are to be used for calibration of XRF instruments for characterization of archaeological samples either in the laboratory or in the field. Successful contribution of non-destructive analytical methods (k 0 -NAA and PIXE) to the IMMACO project and to the certification of the five reference materials is presented. (author)

Joining of Tungsten Armor Using Functional Gradients

International Nuclear Information System (INIS)

John Scott O'Dell

2006-01-01

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.

Problems of tungsten crack resistance optimization

International Nuclear Information System (INIS)

Babak, A.V.; Uskov, E.I.

1986-01-01

Technically pure and precipitation-hardening tungsten is studied for its crack resistance in the initial and hardened states at the temperatures of 20...2000 deg C. Results of the study are presented. It is shown that hardening of tungsten base alloys in oil from the temperature corresponding to the upper boundary of the temperature region of ductile-brittle transition increases a crack propagation resistance of the studied materias at elevated and high temperatures

Characterization of plasma coated tungsten heavy alloy

International Nuclear Information System (INIS)

Bose, A.; Kapoor, D.; Lankford, J. Jr.; Nicholls, A.E.

1996-01-01

The detrimental environmental impact of Depleted Uranium-based penetrators have led to tremendous development efforts in the area of tungsten heavy alloy based penetrators. One line of investigation involves the coating of tungsten heavy alloys with materials that are prone to shear localization. Plasma spraying of Inconel 718 and 4340 steel have been used to deposit dense coatings on tungsten heavy alloy substrates. The aim of the investigation was to characterize the coating primarily in terms of its microstructure and a special push-out test. The paper describes the results of the push-out tests and analyzes some of the possible failure mechanisms by carrying out microstructural characterization of the failed rings obtained from the push out tests

Metallurgical and mechanical examinations of steel–copper joints arc welded using bronze and nickel-base superalloy filler materials

International Nuclear Information System (INIS)

Velu, M.; Bhat, Sunil

2013-01-01

Highlights: ► Optical and scanning electron microscopy show defect free weld interfaces. ► Energy dispersive spectroscopy shows low dilution level of the weld by Fe. ► XRD studies show no brittle intermetallic phases in the weld interfaces. ► Weld interfaces did not fail during tensile, transverse bending and impact tests. ► The joint exhibits superior strength properties than that of bronze filler. - Abstract: The paper presents metallurgical and mechanical examinations of joints between dissimilar metals viz. copper (UNSC11000) and alloy steel (En31) obtained by Shielded Metal Arc Welding (SMAW) using two different filler materials, bronze and nickel-base super alloy. The weld bead of the joint with bronze-filler displayed porosity, while that with nickel-filler did not. In tension tests, the weldments with bronze-filler fractured in the centre of the weld, while those with nickel-filler fractured in the heat affected zone (HAZ) of copper. Since the latter exhibited higher strength than the former, all the major tests were undertaken over the joints with nickel-filler alone. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) indicated corrugated weld interfaces and favorable elemental diffusions across them. X-ray diffraction (XRD) studies around the weld interfaces did not reveal any detrimental intermetallic compounds. Transverse bending tests showed that flexural strengths of the weldments were higher than the tensile strengths. Transverse side bend tests confirmed good ductility of the joints. Shear strength of the weld-interface (Cu–Ni or Ni–steel) was higher than the yield strength of weaker metal. Microhardness and Charpy impact values were measured at all the important zones across the weldment

Pulse current electrodeposition of tungsten coatings on V–4Cr–4Ti alloy

International Nuclear Information System (INIS)

Jiang, Fan; Zhang, Yingchun; Li, Xuliang

2015-01-01

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 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 18 cm −2

Tungsten/copper composite deposits produced by a cold spray

International Nuclear Information System (INIS)

Kang, Hyun-Ki; Kang, Suk Bong

2003-01-01

An agglomerated tungsten/copper composite powder was both cold sprayed and plasma sprayed onto a mild steel substrate for electronic package applications. Most pores resulting from the spraying were found in the vicinity of the tungsten-rich regions of the final product. The levels of porosity varied with the amount of tungsten present. No copper oxidation was found at the cold-sprayed deposit, but relatively high copper oxidation was observed at the plasma-sprayed deposit

Behavior of porous tungsten under shock compression at room temperature

International Nuclear Information System (INIS)

Dandekar, D.P.; Lamothe, R.M.

1977-01-01

This work reports the results of room-temperature shock-compression experiments on porous tungsten. The porous tungsten was fabricated by sintering 1-μm tungsten particles. The initial density of the material was 15290 kg/m 3 . Around 97% of the pores in the material were interconnected. The main features of the results are as follows: (1) porous tungsten behaves as a linear elastic material to 1.43 GPa; (2) the shock wave following the elastic precursor is unstable in the material in the stress range 1.43--2.7 GPa; (3) a stable two-wave structure is established at and above 6.4 GPa; (4) the response of porous tungsten is accurately described by the Mie-Grueneisen equation of state at stresses above 4.9 GPa, the stress at which the voids suffer a complete extinction in the material; (5) the deformations induced in the material due to shock compression are irreversible; (6) the recentered Hugoniot of porous tungsten becomes stiffer with the increasing magnitude of initial compressive stress

Molecular dynamics study of grain boundary diffusion of hydrogen in tungsten

International Nuclear Information System (INIS)

Von Toussaint, U; Gori, S; Manhard, A; Höschen, T; Höschen, C

2011-01-01

Understanding the influence of the microstructure of tungsten on hydrogen transport is crucial for the use of tungsten as first-wall material in fusion reactors. Here, we report the results of molecular dynamics and transition state studies on the influence of grain boundaries in tungsten on the transport of hydrogen. An exhaustive mapping of possible minimum activation energy migration trajectories for hydrogen as the trace impurity reveals a strongly modified activation energy distribution in the neighborhood of grain boundaries together with an altered connectivity matrix. The results indicate that grain boundaries in polycrystalline tungsten may provide an important transport channel, especially for neutron-damaged tungsten.

Interspecific variation in resistance of Asian, European, and North American birches (Betula spp.) to bronze birch borer (Coleoptera: Buprestidae).

Science.gov (United States)

Nielsen, David G; Muilenburg, Vanessa L; Herms, Daniel A

2011-06-01

Bronze birch borer (Agrilus anxius Gory) is the key pest of birches (Betula spp.) in North America, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. In a 20-yr common garden experiment initiated in 1979 in Ohio, North American birch species, including paper birch (Betula papyrifera Marshall), 'Whitespire' gray birch (Betula populifolia Marshall), and river birch (Betula nigra L.), were much more resistant to bronze birch borer than species indigenous to Europe and Asia, including European white birch (Betula pendula Roth), downy birch (Betula pubescens Ehrh.), monarch birch (Betula maximowicziana Regel), and Szechuan white birch (Betula szechuanica Jansson). Within 8 yr of planting, every European white, downy, and Szechuan birch had been colonized and killed, although 100% of monarch birch had been colonized and 88% of these plants were killed after nine years. Conversely, 97% of river birch, 76% of paper birch, and 73% Whitespire gray birch were alive 20 yr after planting, and river birch showed no evidence of colonization. This pattern is consistent with biogeographic theory of plant defense: North American birch species that share a coevolutionary history with bronze birch borer were much more resistant than naïve hosts endemic to Europe and Asia, possibly by virtue of evolution of targeted defenses. This information suggests that if bronze birch borer were introduced to Europe or Asia, it could threaten its hosts there on a continental scale. This study also exposed limitations of anecdotal observation as evidence of host plant resistance.

Surface composition of carburized tungsten trioxide and its catalytic activity

International Nuclear Information System (INIS)

Nakazawa, M.; Okamoto, H.

1985-01-01

The surface composition and electronic structure of carburized tungsten trioxide are investigated using x-ray photoelectron spectroscopy (XPS). The relationship between the surface composition and the catalytic activity for methanol electro-oxidation is clarified. The tungsten carbide concentration in the surface layer increases with the carburization time. The formation of tungsten carbide enhances the catalytic activity. On the other hand, the presence of free carbon or tungsten trioxide in the surface layer reduces the activity remarkably. It is also shown that, the higher the electronic density of states near the Fermi level, the higher the catalytic activity

Study of tungsten based positron moderators

International Nuclear Information System (INIS)

Lucio, O.G. de; Pérez, M.; Mendoza, U.; Morales, J.G.; Cruz, J.C.; DuBois, R.D.

2015-01-01

Positrons and how they interact with matter has a growing interest in many fields. Most of their uses require the production of slow positron beams with a well-defined energy, but since these particles are usually generated by means of a radioactive source, they are fast and with a broad distribution of energies. For this reason it is necessary to moderate them to lower energies via inelastic collisions. Then, they can be accelerated to the desired energies. This requires the use of a moderator. Tungsten is one of the most commonly used moderator materials because of its reasonable efficiency and relatively low cost. In this work we present different methods of producing transmission tungsten-based moderators, with particular interest in a combination of tungsten thin foils and grids. We also show results about the characterization of these moderators by ion beam analysis and microscopy techniques along with their relative moderation efficiencies

Study of tungsten based positron moderators

Energy Technology Data Exchange (ETDEWEB)

Lucio, O.G. de; Pérez, M.; Mendoza, U.; Morales, J.G.; Cruz, J.C. [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México DF (Mexico); DuBois, R.D. [Missouri University of Science and Technology, Rolla, MO 65409 (United States)

2015-07-01

Positrons and how they interact with matter has a growing interest in many fields. Most of their uses require the production of slow positron beams with a well-defined energy, but since these particles are usually generated by means of a radioactive source, they are fast and with a broad distribution of energies. For this reason it is necessary to moderate them to lower energies via inelastic collisions. Then, they can be accelerated to the desired energies. This requires the use of a moderator. Tungsten is one of the most commonly used moderator materials because of its reasonable efficiency and relatively low cost. In this work we present different methods of producing transmission tungsten-based moderators, with particular interest in a combination of tungsten thin foils and grids. We also show results about the characterization of these moderators by ion beam analysis and microscopy techniques along with their relative moderation efficiencies.

OEDGE modeling for the planned tungsten ring experiment on DIII-D

Directory of Open Access Journals (Sweden)

J.D. Elder

2017-08-01

Full Text Available The OEDGE code is used to model tungsten erosion and transport for experiments with toroidal rings of high-Z metal tiles in the DIII-D tokamak. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasma impurity simulations. A new model for tungsten erosion in OEDGE was developed which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. These values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport, the choice of tungsten atomic physics data used in the model (in particular ionization rate for W-atoms, and the model of the carbon flux and energy used for calculating the tungsten source due to sputtering. Core tungsten density is found to be of order 1015m−3 (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned with density decaying into the scrape off layer. For the typical core density in the plasma conditions examined of 2 to 4�

Improved multifilamentary Nb3Sn conductors produced by the titanium-bronze process

International Nuclear Information System (INIS)

Tachikawa, K.; Itoh, K.; Kamata, K.; Moriai, H.; Tada, N.

1985-01-01

The effects of a titanium addition to the bronze matrix of superconducting Nb 3 Sn wires have been investigated. The titanium addition to the matrix remarkably increases the Nb 3 Sn growth rate and the high-field, critical current density of the wire. An overall critical-current density of 3.8 . 10 4 A/cm 2 at 15 T has been obtained for the multifilamentary Nb/Cu-7.5 at.% Sn-0.4 at.% Ti wire with 4.7 μm-diameter 31 x 331 cores. The anisotropy in the critical current with respect to the field direction becomes larger with increasing aspect ratio of the rectangular-shaped multifilamentary wires. A 9.5 mm wide and 1.8mm thick Nb/Cu-7.5Sn-0.4Ti conductor with 5 μm-diameter 349 x 361=125 989 cores has been successfully fabricated on an industrial scale. This conductor carries a superconducting current of over 1300 A at 16.5 T. The newly developed Ti-bronze Nb 3 Sn conductor makes it feasible to generate a field of proportional 15 T in a large diameter bore. (orig.)

Generation of nanoparticles of bronze and brass by laser ablation in liquid

Energy Technology Data Exchange (ETDEWEB)

Sukhov, I.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A., E-mail: Shafeev@kapella.gpi.ru [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Voronov, V.V. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Sygletou, M. [Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Department of Physics, University of Crete, Vassilika Vouton, GR-711 10, Heraklion (Greece); Stratakis, E.; Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece)

2014-05-01

Nanoparticles of brass and bronze are generated by ablation of corresponding bulk targets in liquid ethanol. The experiments were performed using three pulsed lasers with different pulse duration: ytterbium fiber laser (80 ns), a Neodymium:YAG laser (10 ps), and femtosecond Ti:sapphire laser (200 fs). The generated nanoparticles (NPs) are characterized by UV–vis absorption spectroscopy, X-ray diffractometry, Raman scattering, and Transmission Electron Microscopy. The size of generated NPs lies in the range 10–25 nm depending on the laser source. The X-ray diffractometry reveals the change of phase composition of brass NPs compared to the initial target in case of ablation with 80 ns laser source, while with 10 ps laser pulses this effect is less pronounced. Brass NPs generated with pico- and femtosecond laser radiation show the plasmon resonance in the vicinity of 560 nm and no plasmon peak for NPs generated with longer laser pulses. Raman analysis shows the presence of Cu{sub 2}O in generated NPs. The stability of generated NPs of both brass and bronze to oxidation is compared to that of Cu NPs generated in similar experimental conditions.

Surface Analysis of Railway Buffers Heads Covered with Bronze Using Laser Cladding

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Sitarz M.

2017-06-01

Full Text Available Railway buffers during the operation are staying in almost permanent contact with each other, creating friction node in the point of contact of two railway buffer heads. In consequence of overcoming track curves, turnouts and unevenness of track, the railway buffer heads moves relative to each other causing friction, which results in its wear. When the wear is excessive, it might be a reason to withdrawn vehicle from service, it causes flattening of buffer head, and in consequence its abnormal cooperation. To avoid this phenomenon the buffer heads should be covered with graphitized grease, but this method has many disadvantages. Accordingly, it was found that it would be beneficial to cover the buffer head with bronze using laser cladding. In this article the metallographic and mechanical analysis of the newly created top layer of railway buffer head are presented. In article the results from tribological tests conducted on Amsler test bench are also presented. Based on test results described in article concluded that the layer of bronze coat on working surface of railway buffer head can be beneficial from operational point of view.

Dense Pure Tungsten Fabricated by Selective Laser Melting

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Dianzheng Wang

2017-04-01

Full Text Available Additive manufacturing using tungsten, a brittle material, is difficult because of its high melting point, thermal conductivity, and oxidation tendency. In this study, pure tungsten parts with densities of up to 18.53 g/cm3 (i.e., 96.0% of the theoretical density were fabricated by selective laser melting. In order to minimize balling effects, the raw polyhedral tungsten powders underwent a spheroidization process before laser consolidation. Compared with polyhedral powders, the spherical powders showed increased laser absorptivity and packing density, which helped in the formation of a continuous molten track and promoted densification.

Horse-mounted invaders from the Russo-Kazakh steppe or agricultural colonists from western Central Asia? A craniometric investigation of the Bronze Age settlement of Xinjiang.

Science.gov (United States)

Hemphill, Brian E; Mallory, J P

2004-07-01

Numerous Bronze Age cemeteries in the oases surrounding the Täklamakan Desert of the Tarim Basin in the Xinjiang Uyghur Autonomous Region, western China, have yielded both mummified and skeletal human remains. A dearth of local antecedents, coupled with woolen textiles and the apparent Western physical appearance of the population, raised questions as to where these people came from. Two hypotheses have been offered by archaeologists to account for the origins of Bronze Age populations of the Tarim Basin. These are the "steppe hypothesis" and the "Bactrian oasis hypothesis." Eight craniometric variables from 25 Aeneolithic and Bronze Age samples, comprising 1,353 adults from the Tarim Basin, the Russo-Kazakh steppe, southern China, Central Asia, Iran, and the Indus Valley, are compared to test which, if either, of these hypotheses are supported by the pattern of phenetic affinities possessed by Bronze Age inhabitants of the Tarim Basin. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (the weighted pair average linkage method and the neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis provide little support for either the steppe hypothesis or the Bactrian oasis hypothesis. Rather, the pattern of phenetic affinities manifested by Bronze Age inhabitants of the Tarim Basin suggests the presence of a population of unknown origin within the Tarim Basin during the early Bronze Age. After 1200 B.C., this population experienced significant gene flow from highland populations of the Pamirs and Ferghana Valley. These highland populations may include those who later became known as the Saka and who may have served as "middlemen" facilitating contacts between East (Tarim Basin, China) and West (Bactria, Uzbekistan) along what later became known as the Great Silk Road. Copyright

On the shear strength of tungsten nano-structures with embedded helium

International Nuclear Information System (INIS)

Smirnov, R.D.; Krasheninnikov, S.I.

2013-01-01

Modification of plastic properties of tungsten nano-structures under shear stress load due to embedded helium atoms is studied using molecular dynamics modelling. The modelling demonstrates that the yield strength of tungsten nano-structures reduces significantly with increasing embedded helium concentration. At high helium concentrations (>10 at%), the yield strength decreases to values characteristic to the pressure in helium nano-bubbles, which are formed in tungsten under such conditions and thought to be responsible for the formation of nano-fuzz on tungsten surfaces irradiated with helium plasma. It is also shown that tungsten plastic flow strongly facilitates coagulation of helium clusters to larger bubbles. The temperature dependencies of the yield strength are obtained. (letter)

Superhard Rhenium/Tungsten Diboride Solid Solutions.

Science.gov (United States)

Lech, Andrew T; Turner, Christopher L; Lei, Jialin; Mohammadi, Reza; Tolbert, Sarah H; Kaner, Richard B

2016-11-02

Rhenium diboride (ReB 2 ), containing corrugated layers of covalently bonded boron, is a superhard metallic compound with a microhardness reaching as high as 40.5 GPa (under an applied load of 0.49 N). Tungsten diboride (WB 2 ), which takes a structural hybrid between that of ReB 2 and AlB 2 , where half of the boron layers are planar (as in AlB 2 ) and half are corrugated (as in ReB 2 ), has been shown not to be superhard. Here, we demonstrate that the ReB 2 -type structure can be maintained for solid solutions of tungsten in ReB 2 with tungsten content up to a surprisingly large limit of nearly 50 atom %. The lattice parameters for the solid solutions linearly increase along both the a- and c-axes with increasing tungsten content, as evaluated by powder X-ray and neutron diffraction. From micro- and nanoindentation hardness testing, all of the compositions within the range of 0-48 atom % W are superhard, and the bulk modulus of the 48 atom % solid solution is nearly identical to that of pure ReB 2 . These results further indicate that ReB 2 -structured compounds are superhard, as has been predicted from first-principles calculations, and may warrant further studies into additional solid solutions or ternary compounds taking this structure type.

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

Helium-induced hardening effect in polycrystalline tungsten

Science.gov (United States)

Kong, Fanhang; Qu, Miao; Yan, Sha; Zhang, Ailin; Peng, Shixiang; Xue, Jianming; Wang, Yugang

2017-09-01

In this paper, helium induced hardening effect of tungsten was investigated. 50 keV He2+ ions at fluences vary from 5 × 1015 cm-2 to 5 × 1017 cm-2 were implanted into polycrystalline tungsten at RT to create helium bubble-rich layers near the surface. The microstructure and mechanical properties of the irradiated specimens were studied by TEM and nano-indentor. Helium bubble rich layers are formed in near surface region, and the layers become thicker with the rise of fluences. Helium bubbles in the area of helium concentration peak are found to grow up, while the bubble density is almost unchanged. Obvious hardening effect is induced by helium implantation in tungsten. Micro hardness increases rapidly with the fluence firstly, and more slowly when the fluence is above 5 × 1016 cm-2. The hardening effect of tungsten can be attributed to helium bubbles, which is found to be in agreement with the Bacon-Orowan stress formula. The growing diameter is the major factor rather than helium bubbles density (voids distance) in the process of helium implantation at fluences below 5 × 1017 cm-2.

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.

A study of scandia and rhenium doped tungsten matrix dispenser cathode

Science.gov (United States)

Wang, Jinshu; Li, Lili; Liu, Wei; Wang, Yanchun; Zhao, Lei; Zhou, Meiling

2007-10-01

Scandia and rhenium doped tungsten powders were prepared by solid-liquid doping combined with two-step reduction method. The experimental results show that scandia was distributed evenly on the surface of tungsten particles. The addition of scandia and rhenium could decrease the particle size of doped tungsten, for example, the tungsten powders doped with Sc 2O 3 and Re had the average size of about 50 nm in diameter. By using this kind of powder, scandia and rhenium doped tungsten matrix with the sub-micrometer sized tungsten grains was obtained. This kind of matrix exhibited good anti-bombardment insensitivity at high temperature. The emission property result showed that high space charge limited current densities of more than 60 A/cm 2 at 900 °C could be obtained for this cathode. A Ba-Sc-O multilayer about 100 nm in thickness formed at the surface of cathode after activation led to the high emission property.

Behavior of tungsten carbide in water stabilized plasma

Czech Academy of Sciences Publication Activity Database

Brožek, Vlastimil; Matějíček, Jiří; Neufuss, Karel

2007-01-01

Roč. 7, č. 4 (2007), s. 213-220 ISSN 1335-8987 R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : water stabilized plasma * tungsten carbide * tungsten hemicarbide * decarburization Subject RIV: BL - Plasma and Gas Discharge Physics

Palaeodemographic and palaeopathological characteristics of individuals buried in three Bronze Age sites from southern Croatia

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M. Novak

2011-12-01

Full Text Available The purpose of this study is to reconstruct paleodemographic and paleopathological characteristics of sixteen individuals (three subadults, seven males and six females buried in three Bronze Age sites (Crip, Matkovići, and Veliki Vanik located in southern Croatia. The analysed sample is characterised by the presence of pathological changes which are often associated with stressful episodes such as anaemia, inadequate nutrition, infectious diseases and the occurrence of parasites. Cribra orbitalia, dental enamel hypoplasia, porotic hyperostosis and periostitis were observed in seven out of sixteen analysed skeletons. One ulnar “parry” fracture and three fractures of the frontal bone strongly suggest the presence of deliberate interpersonal violence within the studied communities. The average life span of the adults, as well as the number and character of the observed pathologies, suggest a relatively poor life quality and harsh living conditions in the studied region during the Bronze Age.

Measurement of ion species produced due to bombardment of 450 eV N{sub 2}{sup +} ions with hydrocarbons-covered surface of tungsten: Formation of tungsten nitride

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India); Bhatt, P. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kumar, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Singh, B.K.; Singh, B.; Prajapati, S. [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India); Shanker, R., E-mail: shankerorama@gmail.com [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India)

2016-08-01

A laboratory experiment has been performed to study the ions that are produced due to collisions of 450 eV N{sub 2}{sup +} ions with a hydrocarbons-covered surface of polycrystalline tungsten at room temperature. Using a TOF mass spectrometry technique, the product ions formed in these collisions have been detected, identified and analyzed. Different ion–surface reaction processes, namely, neutralization, reflection, surface induced dissociation, surface induced chemical reactions and desorption are observed and discussed. Apart from the presence of desorbed aliphatic hydrocarbon and other ions, the mass spectra obtained from the considered collisions show the formation and sputtering of tungsten nitride (WN). A layer of WN on tungsten surface is known to decrease the sputtering of bulk tungsten in fusion devices more effectively than when the tungsten is bombarded with other seeding gases (He, Ar). It is further noted that there is a negligible diffusion of N in the bulk tungsten at room temperature.

Tungsten coatings electro-deposited on CFC substrates from oxide molten salt

Energy Technology Data Exchange (ETDEWEB)

Sun, Ningbo; Zhang, Yingchun, E-mail: zycustb@163.com; Lang, Shaoting; Jiang, Fan; Wang, Lili

2014-12-15

Tungsten is considered as plasma facing material in fusion devices because of its high melting point, its good thermal conductivity, its low erosion rate and its benign neutron activation properties. On the other hand, carbon based materials like C/C fiber composites (CFC) have been used for plasma facing materials (PFMs) due to their high thermal shock resistance, light weight and high strength. Tungsten coatings on CFC substrates are used in the JET divertor in the frame of the JET ITER-like wall project, and have been prepared by plasma spray (PS) and other techniques. In this study, tungsten coatings were electro-deposited on CFC from Na{sub 2}WO{sub 4}–WO{sub 3} molten salt under various deposition parameters at 900 °C in air. In order to obtain tungsten coatings with excellent performance, the effects of pulse duration ratio and pulse current density on microstructures and crystal structures of tungsten coatings were investigated by X-ray diffraction (XRD, Rigaku Industrial Co., Ltd., D/MAX-RB) and a scanning electron microscope (SEM, JSM 6480LV). It is found that the pulsed duration ratio and pulse current density had a significant influence on tungsten nucleation and electro-crystallization phenomena. SEM observation revealed that intact, uniform and dense tungsten coatings formed on the CFC substrates. Both the average grain size and thickness of the coating increased with the pulsed current density. The XRD results showed that the coatings consisted of a single phase of tungsten with the body centered cubic (BCC) structure. The oxygen content of electro-deposited tungsten coatings was lower than 0.05%, and the micro-hardness was about 400 HV.

Advanced smart tungsten alloys for a future fusion power plant

Science.gov (United States)

Litnovsky, A.; Wegener, T.; Klein, F.; Linsmeier, Ch; Rasinski, M.; Kreter, A.; Tan, X.; Schmitz, J.; Mao, Y.; Coenen, J. W.; Bram, M.; Gonzalez-Julian, J.

2017-06-01

The severe particle, radiation and neutron environment in a future fusion power plant requires the development of advanced plasma-facing materials. At the same time, the highest level of safety needs to be ensured. The so-called loss-of-coolant accident combined with air ingress in the vacuum vessel represents a severe safety challenge. In the absence of a coolant the temperature of the tungsten first wall may reach 1200 °C. At such a temperature, the neutron-activated radioactive tungsten forms volatile oxide which can be mobilized into atmosphere. Smart tungsten alloys are being developed to address this safety issue. Smart alloys should combine an acceptable plasma performance with the suppressed oxidation during an accident. New thin film tungsten-chromium-yttrium smart alloys feature an impressive 105 fold suppression of oxidation compared to that of pure tungsten at temperatures of up to 1000 °C. Oxidation behavior at temperatures up to 1200 °C, and reactivity of alloys in humid atmosphere along with a manufacturing of reactor-relevant bulk samples, impose an additional challenge in smart alloy development. First exposures of smart alloys in steady-state deuterium plasma were made. Smart tungsten-chroimium-titanium alloys demonstrated a sputtering resistance which is similar to that of pure tungsten. Expected preferential sputtering of alloying elements by plasma ions was confirmed experimentally. The subsequent isothermal oxidation of exposed samples did not reveal any influence of plasma exposure on the passivation of alloys.

Precipitation formation in recrystallized nickel-plated non-sag tungsten wire

International Nuclear Information System (INIS)

Lai, Z.H.

1994-01-01

It is well established that some metals, such as palladium and nickel, can easily penetrate into tungsten by fast diffusion via crystal defects such as grain boundaries and dislocations. As a result of the fast penetration of these so called activators the recrystallization temperature of heavily drawn non-sag tungsten wire can be lower from about 2,000 C to about 1,000 C, thus the application of the tungsten wire, serving as reinforcement material in metal matrix composites used at high temperatures, is limited. An interesting question is in which form these activators exist in the recrystallized tungsten wire. It is generally believed that W-Ni intermediate compounds could form in the recrystallized material, presumably at grain boundaries. The free energy difference between the pure tungsten fibbers and the precipitating W(Ni) solid solution was suggested as the chemical driving force which governed the recrystallization process. The presence of nickel in small particles had also been observed in recrystallized grains of nickel plated tungsten wires using scanning electron microscopy (SEM) and secondary ion mass spectroscopy. These particles were considered to be nickel rich precipitates. However, a detailed investigation of the precipitation process has not been reported. In the present work an investigation of the structure, composition and distribution of nickel rich particles precipitated in recrystallized grains of nickel plated heavily drawn non-sage tungsten wires was carried out using analytical electron microscopy (AEM)

Crack resistance of tungsten strengthened by dispersed refractory oxides

International Nuclear Information System (INIS)

Babak, A.V.; Uskov, E.I.

1984-01-01

Investigation results are presented for crack resistance of commercial tungsten, obtained during specimen testing at temperatures of 20 deg C to Tsub(cr) (upper boundary of temperature range of ductile-brittle transition). Comparison of s-n diagrams and temperature dependences of crack resistance are conducted for commercial tungsten and tungsten strengthened by refractory oxides. It is shown that dispersion hardening increases crack resistance in the temperature range of 20 to 2000 deg C but the upper boundary of ductile-brittle shifts to the side of higher temperatures

Electron work function of stepped tungsten surfaces

International Nuclear Information System (INIS)

Krahl-Urban, B.

1976-03-01

The electron work function of tungsten (110) vicinal faces was measured with the aid of thermionic emission, and its dependence on the crystallographic orientation and the surface structure was investigated. The thermionic measurements were evaluated with the aid of the Richardson plot. The real temperature of the emitting tungsten faces was determined with an accuracy of +- 0.5% in the range between 2,200 and 2,800 K. The vicinal faces under investigation have been prepared with an orientation exactness of +- 15'. In the tungsten (110) vicinal faces under investigation, a strong dependence of the temperature coefficient d PHI/dT of the work function on the crystallographic orientation was found. A strong influence of the edge structure as well as of the step density on the temperature coefficient was observed. (orig./HPOE) [de

Element 74, the Wolfram Versus Tungsten Controversy

Energy Technology Data Exchange (ETDEWEB)

Holden,N.E.

2008-08-11

Two and a quarter centuries ago, a heavy mineral ore was found which was thought to contain a new chemical element called heavy stone (or tungsten in Swedish). A few years later, the metal was separated from its oxide and the new element (Z=74) was called wolfram. Over the years since that time, both the names wolfram and tungsten were attached to this element in various countries. Sixty years ago, IUPAC chose wolfram as the official name for the element. A few years later, under pressure from the press in the USA, the alternative name tungsten was also allowed by IUPAC. Now the original, official name 'wolfram' has been deleted by IUPAC as one of the two alternate names for the element. The history of this controversy is described here.

Abnormal photothermal effect of laser radiation on highly defect oxide bronze nanoparticles under the sub-threshold excitation of absorption

Science.gov (United States)

Gulyaev, P.; Kotvanova, M.; Omelchenko, A.

2017-05-01

The mechanism of abnormal photo-thermal effect of laser radiation on nanoparticles of oxide bronzes has been proposed in this paper. The basic features of the observed effect are: a) sub-threshold absorption of laser radiation by the excitation of donor-like levels formed in the energy gap due to superficial defects of the oxide bronze nano-crystals; b) an interband radiationless transition of energy of excitation on deep triplet levels and c) consequent recombination occurring at the plasmon absorption. K or Na atoms thermally intercalated to the octahedral crystal structure of TiO2 in the wave SHS combustion generate acceptor levels in the gap. The prepared oxide bronzes of the non-stoichiometric composition NaxTiO2 and KxTiO2 were examined by high resolution TEM, and then grinded in a planetary mill with powerful dispersion energy density up to 4000 J/g. This made it possible to obtain nanoparticles about 50 nm with high surface defect density (1017-1019 cm-2 at a depth of 10 nm). High photo-thermal effect of laser radiation on the defect nanocrystals observed after its impregnation into cartilaginous tissue exceeds 7 times in comparison with the intact ones.

Friction and wear of ball bearings in liquid sodium environment. Pt. 1

International Nuclear Information System (INIS)

Kleefeldt, K.; Gering, G.

1975-07-01

This report describes sodium experiments with ball bearings, fabricated out of five different materials, i.e. tool steel (s-6-5-2), stainless high speed steel (BG 42), stellite, ferro-titanit (WF 13.5) and tungsten carbide/cobalt cermet (GT 10/20). With each material four cageless bearings of the type 6207 were tested in task 1 under the following test conditions, in order to determine the most promising material for further investigations: test temperature 400 0 C, axial load 300 kp, speed 200 min -1 , total revolutions 0.2 x 10 6 , oxygen concentration [de

Development and optimisation of tungsten armour geometry for ITER divertor

International Nuclear Information System (INIS)

Makhankov, A.; Mazul, I.; Safronov, V.; Yablokov, N.

1998-01-01

The plasma facing components (PFC) of the future thermonuclear reactor in great extend determine the time of non-stop operation of the reactor. In current ITER project the most of the divertor PFC surfaces are covered by tungsten armour. Therefore selection of tungsten grade and attachment scheme for joining the tungsten armour to heat sink is a matter of great importance. Two attachment schemes for highly loaded components (up to 20 MW/m 2 ) are described in this paper. The small size mock-ups were manufactured and successfully tested at heat fluxes up to 30 MW/m 2 in screening test and up to 20 MW/m 2 at thermal fatigue test. One mock-up with four different tungsten grades was tested by consequent thermal shock (15 MJ/m 2 at 50 μs) and thermal cycling loading (15 MW/m 2 ). The damages that could lead to mock-up failure were not found but the behaviour of tungsten grades was quite different. (author)

Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading

Science.gov (United States)

Duman, M. S.; Kaplan, E.; Cuvalcı, O.

2018-01-01

The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. ‘Permaglide Plain Bearings P10’ type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.

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.

Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

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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.

Development of technology and properties investigation of steel/bronze joints proposed for ITER HHF components manufacturing

International Nuclear Information System (INIS)

Kalinin, G.; Krestnikov, N.S.; Strebkov, Y.S.; Abramov, V.Y.; Gervash, A.; Mazul, I.; Zolotarev, V.B.; Fabritsiev, S.A.

2007-01-01

Full text of publication follows: During the development of ITER HHF components manufacturing it is necessary to provide reliable joints between heat sink material made of CuCrZr bronze and the supporting construction made of austenitic steel. Four different methods have been tried out: - Hot Isostatic Pressing (HIP), - HIP assisted brazing, - furnace assisted brazing, - Casting. The investigation of structure and properties of joints show that HIP and casting provide the better results than the other technologies. However, HIP is relatively expensive technology, and big size HIP furnace is required for the full scale components manufacturing that are not available n RF now. Therefore, casting was selected as a reference manufacturing technology for the primary wall of ITER modules n RF. The paper summarizes the results of bronze/steel joints manufacturing and investigation of their properties. (authors)

Emission property of scandia and Re doped tungsten matrix dispenser cathode

International Nuclear Information System (INIS)

Wang Jinshu; Wang Yanchun; Liu Wei; Li Lili; Wang Yiman; Zhou Meiling

2008-01-01

Scandia and rhenium doped tungsten powders have been prepared by solid-liquid doping combined with two-step reduction method. The experimental results show that scandia distributes evenly in the doped tungsten powder. Moreover, the addition of scandia and rhenium could decrease the particle size of tungsten. By using this kind of powder, scandia and rhenium doped tungsten matrix with sub-micrometer sized tungsten grains and a uniform distribution of Sc 2 O 3 together with high pore density has been obtained. The emission property result shows that high space charge limited current density of more than 30 A/cm 2 at 850 deg. C has been obtained for this cathode. This excellent emission capability results from an active layer uniformly covering the sub-micron structure framework of the cathodes

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.

Mobility in Central European Late Eneolithic and Early Bronze Age: femoral cross-sectional geometry

Czech Academy of Sciences Publication Activity Database

Sládek, Vladimír; Berner, M.; Sailer, R.

2006-01-01

Roč. 130, č. 3 (2006), s. 320-332 ISSN 0002-9483 R&D Projects: GA ČR GP206/01/D018 Institutional research plan: CEZ:AV0Z60930519 Keywords : biomechanics * mobility * bone strength * Late Eneolithic * Early Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 2.136, year: 2006

Evaporation of tungsten in vacuum at low hydrogen and water vapor pressures

International Nuclear Information System (INIS)

Andrievskij, R.A.; Galkin, E.A.; Khromonozhkin, V.V.

1981-01-01

The results of experimental investigations of tungsten evaporation rates in the temperature range 1650-2500 K, partial hydrogen and water vapours pressures 1x10 -5 -10 Pa are presented. Experi-- mental plant, equipment employed and radiometric technique of tungsten evaporation study are described. The dependences of evaporation rate and probabilities of tungsten oxidation by residual vacuum water vapours and dependences of tungsten evaporation rate on partial hydrogen and water vapours pressures are determined [ru

The Romanesque Bronze Doors at Gniezno Cathedral Church: Some New Remarks

Directory of Open Access Journals (Sweden)

Tomasz Węcławowicz

2017-06-01

Full Text Available Among many Romanesque bronze doors in Europe the old entrance doors of the metropolitan cathedral in Gniezno, in the North Poland, are exceptional. For over a century many historians and historians of art have been trying to understand and explain its iconographic phenomenon. The Polish, Czech and German scholars have so far been unable to identify with any conviction, either the iconographic models or artistic provenance of the workshop. There were suggested some connections of the alleged bishop patrons to France and there were emphasizes technological possibilities of foundry workshops at the Meuse Valley. This “Meuse hypothesis” based mainly on historical suggestions became established as a certainty. However, it is important to emphasize the significant difference between the creator of the composition and of the craftsman who cast the bronze door. Years ago only Lech Kalinowski pointed out some general formal similarities to the North Italian sculpture. The purpose of this paper is to develop Kalinowski’s suggestions and to emphasise the puzzling similarities between details of Gniezno doors and some Emilian works executed by Master Wiligelmo da Modena and Master Nicolò. The concept of Italian relationship from Emilia province seems to be better for the comparative analysis than relationship with Meuse Valley based mostly on historical context. Crucial here is the additional, parallel analysis of the portal decoration in Czerwinsk Abbey.

Color in 'tungsten trioxide' thin films

International Nuclear Information System (INIS)

Gerard, P.; Deneuville, A.; Hollinger, G.; Duc, Tran Minh

1977-01-01

We show that evaporated tungsten trioxide amorphous layers commonly used in electrochromic displays actually have the composition WO_2_._7H_y (0.2< y<0.5). We emphasize that coloration of virgin transparent films can be obtained without injection of any external ion into the layer, and further that around a critical substoichiometry by sputtering, namely, WO_2_._5, one can prepare blue virgin layers without any hydrogen. The effect of substoichiometry on the valence of tungsten atoms has been followed by XPS measurements of sputtered layers.

Color in ''tungsten trioxide'' thin films

International Nuclear Information System (INIS)

Gerard, P.; Deneuville, A.; Hollinger, G.; Tran Minh Duc

1977-01-01

We show that evaporated tungsten trioxide amorphous layers commonly used in electrochromic displays actually have the composition WO/sub 2.7/H/sub y/ (0.2< y<0.5). We emphasize that coloration of virgin transparent films can be obtained without injection of any external ion into the layer, and further that around a critical substoichiometry by sputtering, namely, WO/sub 2.5/, one can prepare blue virgin layers without any hydrogen. The effect of substoichiometry on the valence of tungsten atoms has been followed by XPS measurements of sputtered layers

Microstructure, mechanical behaviour and fracture of pure tungsten wire after different heat treatments

DEFF Research Database (Denmark)

Zhao, P.; Riesch, J.; Höschen, T.

2017-01-01

Plastic deformation of tungsten wire is an effective source of toughening tungsten fibre-reinforced tungsten composites (Wf/W) and other tungsten fibre-reinforced composites. To provide a reference for optimization of those composites, unconstrained pure tungsten wire is studied after various hea...... a rather different microstructure. As-fabricated wire and wire recrystallized at 1273 K for 3 h show fine grains with a high aspect ratio and a substantial plastic deformability: a clearly defined tensile strength, high plastic work, similar necking shape, and the characteristic knife...

Microscopic investigations of chemo-mechanical polishing of tungsten

International Nuclear Information System (INIS)

Lim, Min Soo; Heide, Paul A.W. van der; Perry, Scott S.; Galloway, Heather C.; Koeck, Deborah C.

2004-01-01

The influence of aqueous solutions of KNO 3 , KClO 3 , and KIO 3 on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO 3 in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO 3 solutions, as compared to KClO 3 and KNO 3 solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action

Microscopic investigations of chemo-mechanical polishing of tungsten

Energy Technology Data Exchange (ETDEWEB)

Lim, Min Soo; Heide, Paul A.W. van der; Perry, Scott S.; Galloway, Heather C.; Koeck, Deborah C

2004-06-15

The influence of aqueous solutions of KNO{sub 3}, KClO{sub 3}, and KIO{sub 3} on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO{sub 3} in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO{sub 3} solutions, as compared to KClO{sub 3} and KNO{sub 3} solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action.

Large area synthesis, characterization, and anisotropic etching of two dimensional tungsten disulfide films

International Nuclear Information System (INIS)

Mutlu, Zafer; Ozkan, Mihrimah; Ozkan, Cengiz S.

2016-01-01

Emergent properties of tungsten disulfide at the quantum confinement limit hold promise for electronic and optoelectronic applications. Here we report on the large area synthesis of atomically thin tungsten disulfide films with strong photoluminescence properties via sulfurization of the pre-deposited tungsten films. Detailed characterization of the pre-deposited tungsten films and tungsten disulfide films are performed using microscopy and spectroscopy methods. By directly heating tungsten disulfide films in air, we have shown that the films tend to be etched into a series of triangular shaped pits with the same orientations, revealing the anisotropic etching behavior of tungsten disulfide edges. Moreover, the dimensions of the triangular pits increase with the number of layers, suggesting a thickness dependent behavior of etching in tungsten disulfide films. This method offers a promising new avenue for engineering the edge structures of tungsten disulfide films. - Highlights: • Large-scale synthesis of WS_2 films is achieved via sulfurization of W films. • Annealing of W films leads to a substantial improvement in the quality of WS_2 films. • WS_2 films show laser power dependent photoluminescence characteristics. • WS_2 films are etched with well-oriented triangular pits upon annealing in air. • Anisotropic oxidative etching is greatly affected by the thickness of WS_2 films.

Abertura floral de Dendranthema grandiflora Tzvelev. ´Bronze Repin´após rmazenamento a frio seguido de “pulsing” Floral opening of Dendranthema grandiflora Tzvelev. ´Bronze Repin´after cold storage followed by pulsing

Directory of Open Access Journals (Sweden)

Rogério Antônio Bellé

2004-02-01

Full Text Available Visando estudar a abertura de inflorescências e a vida de vaso de crisântemo (Dendranthema grandiflora Tzvelev. ‘Bronze Repin’ colhido precocemente, montou-se um experimento em delineamento inteiramente casualizado bifatorial 2 x 6 com cinco repetições, realizado no Departamento de Fitotecnia da Universidade Federal de Santa Maria. As hastes foram armazenadas a 2ºC ou 5ºC por sete dias, sendo em seguida tratadas com soluções de “pulsing” por 24h e mantidas em vasos com água de torneira, renovada a cada dois dias. As soluções utilizadas foram: Água (testemunha; Tiosulfato de Prata-STS 11mg.L-1 (Crysal AVB; Ácido Giberélico-GA3 50mg.L-1 (Pro-gibb; Hipoclorito de Sódio-NaOCl 200mg.L-1; 8-Hidroxiquinolina-8-HQ 100mg.L-1; Tiabendazole-TIBA 100mg.L-1(Tecto 100. Com exceção da testemunha, as outras soluções continham 2% de Sacarose. Com estes tratamentos, observou-se que não foi possível uma abertura perfeita da inflorescência, mas a vantagem foi de prolongar a sua vida, podendo-se colocá-las no mercado num momento mais oportuno.The study of opening of inflorescences and the vase life (Dendranthema grandiflora Tzvelev. ‘Bronze Repin’ early picked of chysanthemum, was carried out in an experiment entirely set up in bifactorial 2 x 6 with five repetitions, at the Department of Fitotecnia of Santa Maria’s Federal University. The stems were stored at 2ºC or 5ºC for 7 days, prior to being treated with pulsing solutions for 24 hours and maintained in vases with distilled water, renewed every two days. The solutions used as follows: Water (control; Silver Thiosulfate-STS 11mg.L-1 (Crysal AVB; Giberelic Acid-GA3 50mg.L-1 (Pro-gibb; Sodium Hipochloride-NaOCl 200mg.L-1; 8-Hidroxyquinoline-8-HQ 100mg.L-1; Tiabendazole-TIBA 100mg.L-1 (Tecto 100. With the exception of the control, all solutions contained 2% sucrose. Perfect opening of the flower was not achieved, but vase life could be extended in order to place them in the

RF induction plasma spheroidization of tungsten powders

International Nuclear Information System (INIS)

Gu Zhogntao; Ye Gaoying; Liu Chuandong; Tong Honghui

2009-01-01

Irregularly-shaped tungsten powders (average granular sizes of 512 μm) have been spheroidized by radio frequency (RF)induction plasma. The effects of feed rate, mode of material dispersion, particle size on spheroidization efficiency are investigated. Experimental results show that the spheroidization efficiency decreases rapidly when the feed rate increases to more than 95 g/min. Only 30% spheroidization efficiency is gained at the feed rate of 135.75 g/min. The spheroidization efficiency is also affected by the flow rate of carrier gas. When the flow rate of carrier gas is 0.12 m 3 /h, the dispersion effect is the best, and the spheroidization efficiency is almost 100%. The apparent density of tungsten powders increases a bit with the increase of spheroidization efficiency. And the particle size uniformity of spheroidized tungsten powders is in accordance with that of original powders. (authors)

Trends in tungsten coil atomic spectrometry

Science.gov (United States)

Donati, George L.

Renewed interest in electrothermal atomic spectrometric methods based on tungsten coil atomizers is a consequence of a world wide increasing demand for fast, inexpensive, sensitive, and portable analytical methods for trace analysis. In this work, tungsten coil atomic absorption spectrometry (WCAAS) and tungsten coil atomic emission spectrometry (WCAES) are used to determine several different metals and even a non-metal at low levels in different samples. Improvements in instrumentation and new strategies to reduce matrix effects and background signals are presented. Investigation of the main factors affecting both WCAAS and WCAES analytical signals points to the importance of a reducing, high temperature gas phase in the processes leading to atomic cloud generation. Some more refractory elements such as V and Ti were determined for the first time by double tungsten coil atomic emission spectrometry (DWCAES). The higher temperatures provided by two atomizers in DWCAES also allowed the detection of Ag, Cu and Sn emission signals for the first time. Simultaneous determination of several elements by WCAES in relatively complex sample matrices was possible after a simple acid extraction. The results show the potential of this method as an alternative to more traditional, expensive methods for fast, more effective analyses and applications in the field. The development of a new metallic atomization cell is also presented. Lower limits of detection in both WCAAS and WCAES determinations were obtained due to factors such as better control of background signal, smaller, more isothermal system, with atomic cloud concentration at the optical path for a longer period of time. Tungsten coil-based methods are especially well suited to applications requiring low sample volume, low cost, sensitivity and portability. Both WCAAS and WCAES have great commercial potential in fields as diverse as archeology and industrial quality control. They are simple, inexpensive, effective

Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

Science.gov (United States)

Schoop, Julius Malte

Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is investigated as a substitutionary process for the current plastic infiltration process. Along with significant reductions in cycle time and resource use, surface quality of cryogenically machined un-infiltrated (as-sintered) porous tungsten has been shown to significantly outperform dry machining. The present study is focused on examining the relationship between machining parameters and cooling condition on the as-machined surface integrity of porous tungsten. The effects of cryogenic pre-cooling, rake angle, cutting speed, depth of cut and feed are all taken into consideration with respect to machining-induced surface morphology. Cermet and Polycrystalline diamond (PCD) cutting tools are used to develop high performance cryogenic machining of porous tungsten. Dry and pre-heated machining were investigated as a means to allow for ductile mode machining, yet severe tool-wear and undesirable smearing limited the feasibility of these approaches. By using modified PCD cutting tools, high speed machining of porous tungsten at cutting speeds up to 400 m/min is achieved for the first time. Beyond a critical speed, brittle fracture and built-up edge are eliminated as the result of a brittle to ductile transition. A model of critical chip thickness ( hc ) effects based on cutting

Chromium and molybdenum diffusion in tungsten single crystals

International Nuclear Information System (INIS)

Klotsman, S.M.; Koloskov, V.M.; Osetrov, S.V.; Polikarpova, I.P.; Tatarinova, G.N.; Timofeev, A.N.

1989-01-01

Consideration is given to results of measuring temperature dependences of diffusion coefficients of homovalent impurities of chromium and molybdenum in tungsten single crystals. It is concluded that the difference of activation energies of selfdiffusion and impurity diffusion in the system 'tungsten-homovalent impurity' is conditioned by interaction of screened potentials of impurity and vacancy with Lazarus-Le Claire model

Diet Reconstructed From an Analysis of Plant Microfossils in Human Dental Calculus From the Bronze Age Site of Shilinggang, Southwestern China

Science.gov (United States)

Zhang, N.; Dong, G.; Yang, X.; Zuo, X.; Kang, L.; Ren, L.; Liu, H.; Li, H.; Min, R.; Liu, X.; Zhang, D.; Chen, F.

2017-12-01

The extracted microfossils from the dental calculus of ancient teeth are a new form of archaeological evidence which can provide direct information on the plant diet of a population. Here, we present the results of analyses of starch grains and phytoliths trapped in the dental calculus of humans who occupied the Bronze Age site of Shilinggang ( 2500 cal yr BP) in Yunnan Province, southwestern China. The results demonstrate that the inhabitants consumed a wide range of plants, including rice, millet, and palms, together with other food plants which have not previously been detected in Yunnan. The discovery of various underground storage organs (USOs; tubers, roots, bulbs, and rhizomes) and acorns complements the application of conventional macrofossil and isotope studies to understand the diet of the Bronze Age human population of Yunnan. The wide variety of plant foods consumed suggests that the inhabitants adopted a broad-spectrum strategy of gathering food and cultivating crops in northwest Yunnan Province in the late Bronze Age at a time when agricultural societies were developed in the central plains of China.

Electronic band structure and charge density wave transition in quasi-2D KMo6O17 purple bronze

Science.gov (United States)

Valbuena, M. A.; Avila, J.; Vyalikh, D. V.; Guyot, H.; Laubschat, C.; Molodtsov, S. L.; Asensio, M. C.

2008-03-01

High resolution angle-resolved photoemission of quasi-2D KMo6O17 purple bronze has been performed in the range from room temperature to 130 K, slightly above the charge density wave (CDW) transition (Tc = 110 K), and down to 35 K (well below Tc). In this paper we report a detailed study of how electronic band structure is affected by this transition driven by the hidden nesting scenario. The expected spectroscopic fingerprints of the CDW phase transition have been found and discussed according to the hidden one dimension and the development of a quasi-commensurate CDW. The excellent agreement between theory and our experimental results makes of potassium purple bronze a reference system for studying this type of instabilities.

Electronic band structure and charge density wave transition in quasi-2D KMo6O17 purple bronze

International Nuclear Information System (INIS)

Valbuena, M A; Avila, J; Asensio, M C; Vyalikh, D V; Laubschat, C; Molodtsov, S L; Guyot, H

2008-01-01

High resolution angle-resolved photoemission of quasi-2D KMo 6 O 17 purple bronze has been performed in the range from room temperature to 130 K, slightly above the charge density wave (CDW) transition (T c = 110 K), and down to 35 K (well below T c ). In this paper we report a detailed study of how electronic band structure is affected by this transition driven by the hidden nesting scenario. The expected spectroscopic fingerprints of the CDW phase transition have been found and discussed according to the hidden one dimension and the development of a quasi-commensurate CDW. The excellent agreement between theory and our experimental results makes of potassium purple bronze a reference system for studying this type of instabilities

Simulation of cracks in tungsten under ITER specific heat loads

International Nuclear Information System (INIS)

Peschany, S.

2006-01-01

The problem of high tritium retention in co-deposited carbon layers on the walls of ITER vacuum chamber motivates investigation of materials for the divertor armour others than carbon fibre composite (CFC). Tungsten is most probable material for CFC replacement as the divertor armour because of high vaporisation temperature and heat conductivity. In the modern ITER design tungsten is a reference material for the divertor cover, except for the separatrix strike point armoured with CFC. As divertor armour, tungsten should withstand severe heat loads at off-normal ITER events like disruptions, ELMs and vertical displacement events. Experiments on tungsten heating with plasma streams and e-beams have shown an intense crack formation at the surface of irradiated sample [ V.I. Tereshin, A.N. Bandura, O.V. Byrka et al. Repetitive plasma loads typical for ITER type-I ELMs: Simulation at QSPA Kh-50.PLASMA 2005. ed. By Sadowski M.J., AIP Conference Proceedings, American Institute of Physics, 2006, V 812, p. 128-135., J. Linke. Private communications.]. The reason for tungsten cracking under severe heat loads is thermo stress. It appears as due to temperature gradient in solid tungsten as in resolidified layer after cooling down. Both thermo stresses are of the same value, but the gradiental stress is compressive and the stress in the resolidified layer is tensile. The last one is most dangerous for crack formation and it was investigated in this work. The thermo stress in tungsten that develops during cooling from the melting temperature down to room temperature is ∼ 8-16 GPa. Tensile strength of tungsten is much lower, < 1 GPa at room temperature, and at high temperatures it drops at least for one order of magnitude. As a consequence, various cracks of different characteristic scales appear at the heated surface of the resolidified layer. For simulation of the cracks in tungsten the numeric code PEGASUS-3D [Pestchanyi and I. Landman. Improvement of the CFC structure to

Surface studies of barium and barium oxide on tungsten and its application to understanding the mechanism of operation of an impregnated tungsten cathode

Science.gov (United States)

Forman, R.

1976-01-01

Surface studies have been made of multilayer and monolayer films of barium and barium oxide on a tungsten substrate. The purpose of the investigation was to synthesize the surface conditions that exist on an activated impregnated tungsten cathode and obtain a better understanding of the mechanism of operation of such cathodes. The techniques employed in these measurements were Auger spectroscopy and work-function measurements. The results of this study show that the surface of an impregnated cathode is identical to that observed for a synthesized monolayer or partial monolayer of barium on oxidized tungsten by evaluating Auger spectra and work-function measurements. Data obtained from desorption studies of barium monolayers on a tungsten substrate in conjunction with Auger and work-function results have been interpreted to show that throughout most of its life an impreganated cathode has a partial monolayer, rather than a monolayer, of barium on its surface.

Microstructural study of tungsten influence on Co-Cr alloys

International Nuclear Information System (INIS)

Karaali, A.; Mirouh, K.; Hamamda, S.; Guiraldenq, P.

2005-01-01

Alloying elements, such as W, Mo, Mn,..., are of a great importance in the preoxidation of dental alloys and, consequently, on the ceramic/metal bond quality. This study deals with the effect of tungsten addition on the microstructural state of Co-Cr dental alloys, before the ceramisation process. These materials were prepared by unidirectional solidification. Their characterization has been carried out, using transmission electron microscopy (TEM) and X-ray diffraction. It shows that the addition of tungsten up to 8 wt.% induces structural transformations, which are believed to be linked to the added amount of tungsten

Tungsten anode tubes with K-edge filters for mammography

Energy Technology Data Exchange (ETDEWEB)

Beaman, S.; Lillicrap, S.C. (Wessex Regional Medical Physics Service, Bath (UK)); Price, J.L. (Jarvis Screening Centre, Guildford (UK))

1983-10-01

Optimum X-ray energies for mammography have previously been calculated using the maximum signal to noise ratio (SNR) per unit dose to the breast, or the minimum exposure for constant SNR. Filters having absorption edges at appropriate energy positions have been used to modify the shape of tungsten anode spectra towards the calculated optimum. The suitability of such spectra for practical use has been assessed by comparing the film image quality and the incident breast dose obtained using a K-edge filtered tungsten anode tube with that obtained using a molybdenum anode. Image quality has been assessed by using a 'random' phantom and by comparing mammograms where one breast was radiographed using a filtered tungsten anode tube and the other using a standard molybdenum anode unit. Relative breast doses were estimated from both ionisation chamber measurements with a phantom and thermoluminescent dosimetry measurements on the breast. Film image quality assessment indicated that the filtered tungsten anode tube gave results not significantly different from those obtained with a molybdenum anode tube for a tissue thickness of about 4 cm and which were better for larger breast thicknesses. Doses could be reduced to between one-half and one-third with the filtered tungsten anode tube.

Tungsten anode tubes with K-edge filters for mammography

International Nuclear Information System (INIS)

Beaman, S.; Lillicrap, S.C.; Price, J.L.

1983-01-01

Optimum X-ray energies for mammography have previously been calculated using the maximum signal to noise ratio (SNR) per unit dose to the breast, or the minimum exposure for constant SNR. Filters having absorption edges at appropriate energy positions have been used to modify the shape of tungsten anode spectra towards the calculated optimum. The suitability of such spectra for practical use has been assessed by comparing the film image quality and the incident breast dose obtained using a K-edge filtered tungsten anode tube with that obtained using a molybdenum anode. Image quality has been assessed by using a 'random' phantom and by comparing mammograms where one breast was radiographed using a filtered tungsten anode tube and the other using a standard molybdenum anode unit. Relative breast doses were estimated from both ionisation chamber measurements with a phantom and thermoluminescent dosimetry measurements on the breast. Film image quality assessment indicated that the filtered tungsten anode tube gave results not significantly different from those obtained with a molybdenum anode tube for a tissue thickness of abut 4 cm and which were better for larger breast thicknesses. Doses could be reduced to between one-half and one-third with the filtered tungsten anode tube. (U.K.)

A Living Landscape : Bronze Age settlement sites in the Dutch river area (c. 2000-800 BC)

NARCIS (Netherlands)

Arnoldussen, Stijn

2008-01-01

"A Living Landscape. Bronze Age settlements in the Dutch river area (c. 2000-800 BC)" Academisch proefschrift over de aard en dynamiek van bronstijdnederzettingen in het rivierengebied. Het bevat een introductie op de geologische processen en de paleogeografie van de Nederlandse rivierdelta als

Cleaning and outgassing studies of machinable tungsten for beamline safety shutters

International Nuclear Information System (INIS)

Liu, C.; Ryding, D.; Nielsen, R.W.; Kruy, T.L.; Kuzay, T.M.

1996-01-01

Machinable tungsten blocks are used as safety shutters in the front ends and the beamlines at the Advanced Photon Source (APS). The machinable tungsten used is characterized as a UHV-compatible metal by the vendor and was developed through a joint research effort with the APS. However, because of the inherent porosity in the sintered tungsten metal, it may present a vacuum problem and has to be subjected to strict vacuum testing before it is put on the beamlines. We have chosen specially heat-treated machinable tungsten with a density of 18 g/cm 3 for safety shutters. In-house-developed, environmentally friendly vacuum cleaning procedures were used. In this paper, we present results of thermal outgassing tests for machinable tungsten safety shutter sets. Each set consists of five blocks and has a total area of 4500 cm 2 . A cleaning procedure using alkaline detergent ultrasonic washes, deionized water rinses, and a 500 degree C vacuum furnace baking was used before outgassing measurements. Outgassing rates 10 hours after initial pump down at room temperature reached ∼1.60x10 -10 Torr·l·s -1 ·cm -2 for machinable tungsten and ∼1.56x10 -10 Torr·l·s -1 ·cm -2 for the stainless steel vacuum chamber. The outgassing rate of machinable tungsten 24 hours after an in situ 48 h bake at 160 degree C is also comparable to that of the stainless steel vacuum chamber. The importance of a 500 degree C vacuum furnace baking has been confirmed by outgassing studies for machinable tungsten sets that were not subject to vacuum furnace baking. copyright 1996 American Institute of Physics

Exposition and Synthesis of Benin Bronze Casting: Emphasis on the Olotan Casters of Benin

Science.gov (United States)

Ifeta, Chris Funke

2016-01-01

The introduction of Western education to Nigeria has brought in its wake great strides toward development. Changes in Benin dates far back to the dawn of the 20th century. This paper investigates the critical role of education in development. The paper integrates interview data collected from bronze casters in Benin. The first section of the paper…

Tungsten-microdiamond composites for plasma facing components

International Nuclear Information System (INIS)

Livramento, V.; Nunes, D.; Correia, J.B.; Carvalho, P.A.; Mardolcar, U.; Mateus, R.; Hanada, K.; Shohoji, N.; Fernandes, H.; Silva, C.; Alves, E.

2011-01-01

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.

Stress in tungsten carbide-diamond like carbon multilayer coatings

NARCIS (Netherlands)

Pujada, B.R.; Tichelaar, F.D.; Janssen, G.C.A.M.

2007-01-01

Tungsten carbide-diamond like carbon (WC-DLC) multilayer coatings have been prepared by sputter deposition from a tungsten-carbide target and periodic switching on and off of the reactive acetylene gas flow. The stress in the resulting WC-DLC multilayers has been studied by substrate curvature.

Raman and IR phonons in ferroelectric Sr.sub.0.35./sub.Ba.sub.0.69./sub.Nb.sub.2./sub.O.sub.6.04./sub. single crystals

Czech Academy of Sciences Publication Activity Database

Buixaderas, Elena; Gregora, Ivan; Hlinka, Jiří; Dec, J.; Lukasiewicz, T.

2013-01-01

Roč. 86, 2-3 (2013), s. 217-229 ISSN 0141-1594 R&D Projects: GA ČR GAP204/10/0616 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectrics * Raman spectroscopy * IR spectroscopy * phonons * relaxors * tungsten-bronze materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.044, year: 2013

Roman Bronze Vessels From the Late Sarmatian Burial of the Lebedevka Burial-Ground in Western Kazakhstan

Directory of Open Access Journals (Sweden)

Treister Mikhail Yuryevich

2015-12-01

Full Text Available This paper is devoted to studying cultural monuments – bronze vessels, a jug and a basin from the barrow no. 1/1967 of the Lebedevka Late Sarmatian burial mound (Western Kazakhstan, dating back to the middle of the 3rd century AD at the latest. These items do not find exact parallels among the bronze vessels of provincial Rome. Although the shape of the jug handle with a curved leaf turned upright between two horizontally arranged swan heads has parallels on the so-called “composite jug with handles” (“gegliederten Henkelkrügen”, the cylindrical form of the jug’s neck peculiar of the glass jugs of allegedly Syrian manufacture of the second half of the 3rd-4th centuries AD is very unusual. Even more unusual is a basin with horizontally bent rim and elaborate handles with pearls on a high narrow stand-ring. The XRF analyses of the Lebedevka jug’s metal revealed that its body and handle were made of a copper-based alloy with very high admixtures of zinc (24-27 % and inconsiderable additions of lead (up to 3 %. A similar alloy was used for manufacturing a vessel in the form of a crouching young negro from Niederbieber. Most objects of provincial Roman import reached Western Kazakhstan via the Bosporan kingdom along the Northern branch of the Silk Road. The above discussed bronze vessels from Lebedevka let suggest, that the nomads could receive some import articles that were brought along the caravan routes leading from Egypt and Syria to the East.

Tungsten alloy research at the US Army Materials Technology Laboratory

International Nuclear Information System (INIS)

Dowding, R.J.

1991-01-01

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

Archaeometric study of a bronze age sword discovered at Giurgiu, Romania

International Nuclear Information System (INIS)

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

2008-01-01

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). The elemental composition of the sword was compared with the composition of other swords from the same geographic area, the Danubian plain from Bulgaria, and Transylvania regions. Both the physical analyzes and the archaeological considerations show that the sword from Giurgiu could be associated with the swords from Bulgaria, having compositional, stylistic, temporal and geographical similitudes. (authors)

Ordering of Nb3Sn layer formed in the bronze process

International Nuclear Information System (INIS)

Agarwal, S.K.; Nagpal, K.C.; Narlikar, A.G.

1986-01-01

The work reported here suggests that the ordering of superconducting Nb 3 Sn compound layers formed in the bronze process is much more intriguing than previously assumed. Various possible mechanisms of ordering of the layers have been examined in conjunction with the observed data on short duration annealed samples. The analysis suggests the ordering to be governed by a sequential operation of both Ist and IInd order kinetics, and seems to fall in line with the studies on disordered bulk samples annealed for long durations. (author)

Effect of two-stage sintering process on microstructure and mechanical properties of ODS tungsten heavy alloy

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyong H. [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701 (Korea, Republic of); Cha, Seung I. [International Center for Young Scientists, National Institute for Materials Science 1-1, Namiki, Tsukuba 305-0044 (Japan); Ryu, Ho J. [DUPIC, Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yusong-gu, Taejon 305-353 (Korea, Republic of); Hong, Soon H. [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701 (Korea, Republic of)], E-mail: shhong@kaist.ac.kr

2007-06-15

Oxide dispersion strengthened (ODS) tungsten heavy alloys have been considered as promising candidates for advanced kinetic energy penetrator due to their characteristic fracture mode compared to conventional tungsten heavy alloy. In order to obtain high relative density, the ODS tungsten heavy alloy needs to be sintered at higher temperature for longer time, however, induces growth of tungsten grains. Therefore, it is very difficult to obtain controlled microstructure of ODS tungsten heavy alloy having fine tungsten grains with full densification. In this study, two-stage sintering process, consisted of primary solid-state sintering and followed by secondary liquid phase sintering, was introduced for ODS tungsten heavy alloys. The mechanically alloyed 94W-4.56Ni-1.14Fe-0.3Y{sub 2}O{sub 3} powders are solid-state sintered at 1300-1450 deg. C for 1 h in hydrogen atmosphere, and followed by liquid phase sintering temperature at 1465-1485 deg. C for 0-60 min. The microstructure of ODS tungsten heavy alloys showed high relative density above 97%, with contiguous tungsten grains after primary solid-state sintering. The microstructure of solid-state sintered ODS tungsten heavy alloy was changed into spherical tungsten grains embedded in W-Ni-Fe matrix during secondary liquid phase sintering. The two-stage sintered ODS tungsten heavy alloy from mechanically alloyed powders showed finer microstructure and higher mechanical properties than conventional liquid phase sintered alloy. The mechanical properties of ODS tungsten heavy alloys are dependent on the microstructural parameters such as tungsten grain size, matrix volume fraction and tungsten/tungsten contiguity, which can be controlled through the two-stage sintering process.

Perovskite structures in the formation of nano-rods in REBa2Cu3O7-δ films self-organization to perovskite structures

International Nuclear Information System (INIS)

Mukaida, Masashi; Kai, Hideki; Shingai, Yuki

2009-01-01

Cubic perovskite structure has been found to play an important role for the nano-rod formation in REBa 2 Cu 3 O 7-δ films. BaWO 4 , with a sheelite structure, and BaNb 2 O 6 , with a tungsten bronze structure, were doped into REBa 2 Cu 3 O 7-δ targets. Laser-deposited, these materials form nano-rods in REBa 2 Cu 3 O 7-δ films accompanied by Ln elements, resulting in the composition of a pseudo-cubic perovskite structure. This was confirmed by selected area electron diffraction patterns (SADP) and composition mapping using energy-dispersive X-ray spectroscopy scanning transmission electron microscope (EDS-STEM) analysis. BaWO 4 with a sheelite structure, and BaNb 2 O 6 with a tungsten bronze structure, doped into targets no longer retain their structures, but can form pseudo-cubic perovskite structures in laser-deposited REBa 2 Cu 3 O 7-δ films. The perovskite crystal structure is thought to be important for nano-rod formation in the laser deposited REBa 2 Cu 3 O 7-δ film. (author)

Analysis of selective laser cleaning of patina on bronze coins

International Nuclear Information System (INIS)

Buccolieri, G; Nassisi, V; Castellano, A; Di Giulio, M; Giuffreda, E; Delle Side, D; Velardi, L; Torrisi, L; Buccolieri, A

2014-01-01

The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

A process for electrodeposition of layers of niobium, vanadium, molybdenum or tungsten, or of their alloys

International Nuclear Information System (INIS)

Diepers, H.; Schmidt, O.

1977-01-01

An improvement is proposed for the process for electrodeposition of layers of niobium, vanadium, molybdenum or tungsten or of their alloys from molten-salt electrolytes (fluorid melts) which is to increase the quality of layers in order to obtain regular thickness and smooth surfaces. According to the invention, a pre-separation is executed on an auxiliary cathode before the (preheated) cathode is immersed. The cathode is only charged for separation after the adjustment of a constant anode potential. It is an advantage that the auxiliary cathode is mechanically and electrically connected with the cathode. As an electrolyte, a mixture of niobium fluorides and a eustetic mixture of potassium fluorides, sodium fluorides and lithium fluorides are particularly suitable for the electrodeposition of miobium. (UWI) [de

FABRICATION OF GAS-FILLED TUNGSTEN-COATED GLASS SHELLS

International Nuclear Information System (INIS)

NIKROO, A; BAUGH, W; STEINMAN, D.A.

2003-09-01

OAK-B135 Deuterium (D 2 ) filled glass shells coated with a high Z element are needed for high energy density (HED) experiments by researchers at Los Alamos National Laboratory. They report here on our initial attempt to produce such shells. Glass shells made using the drop tower technique were coated with gold, palladium or tungsten, or a mixture of two of these elements. It was found that gold and palladium coatings did not stick well to the glass and resulted in poor or delaminated films. Tungsten coatings resulted in films suitable for these targets. Bouncing of shells during coating resulted in uniform tungsten coatings, but the surface of such coatings were filled with small nodules. Proper agitation of shells using a tapping technique resulted in smooth films with minimal particulate contamination. For coating rates of ∼ 0.15 (micro)m/hr coatings with ∼ 2 nm RMS surface finish could be deposited. The surface roughness of coatings at higher rates, 0.7 (micro)m/hr, was considerably worse (∼ 100 nm RMS). The columnar structure of the coatings allowed permeation filling of the tungsten coated glass shells with deuterium at 300 C

Study of thermoelectron emission of oxidized tungsten sponge in cesium atom flow

International Nuclear Information System (INIS)

Tursunmetov, K.A.; Sabirov, A.K.

1993-01-01

Thermoelectron emission of a tungsten sponge with 30-40% porosity is studied. The tungsten sponge is produced of fine-grain tungsten powder (diameter - 1-2 μm) according to standard technology. It is shown that tungsten sponge oxidation at T=1000 K with subsequent heating in vacuum at T=1100 K allows one to obtain the minimal stable and reproducible work function at the level of 1.03-1.05 eV in a flux of cesium atoms. Estimations show that effective emitting surface is 15-20 times as much as the polycrystal surface

Morphological characterisation and spectroscopic studies of the corrosion behaviour of tungsten heavy alloys

International Nuclear Information System (INIS)

Ogundipe, A.; Greenberg, B.; Braida, W.; Christodoulatos, C.; Dermatas, D.

2006-01-01

Tungsten-based alloys have been used in a wide variety of industrial and military applications. These alloys are composed mainly of tungsten (88-95%) with various combinations of nickel, cobalt, iron and copper usually making up the remaining fraction. The corrosion behaviours of five munitions grade tungsten alloys of interest have been examined using immersion tests and wet-dry cycle tests to determine the mechanisms involved in the release of the metallic components. Analyses carried out using SEM, EDS and grazing incidence XRD techniques, show the release of tungsten as well as alloying elements due to galvanic corrosion resulting from the difference in electrode potential between the tungsten phase and the binder phase in all cases studied. The extent of corrosion was directly related with the dissolution of tungsten in the binder phase during the sintering stage of manufacture. In W-Ni-Co-Fe alloys binder phase corrosion was observed while the relatively noble tungsten phase was less affected. The reverse was observed for a W-Cu alloy

Tape cast isotropic, fine-grained tungsten for thermo-cyclic loading applications

Energy Technology Data Exchange (ETDEWEB)

Sommerer, Mathias, E-mail: Mathias.Sommerer@tum.de [Lehrstuhl für Werkstoffkunde und Werkstoffmechanik, Technische Universität München, Boltzmannstr. 15, 85748 Garching (Germany); Li, Muyuan [Max-Planck-Institut für Plasma Physik, Boltzmannstraße 2, 85748 Garching (Germany); Werner, Ewald [Lehrstuhl für Werkstoffkunde und Werkstoffmechanik, Technische Universität München, Boltzmannstr. 15, 85748 Garching (Germany); Dewitz, Hubertus von; Walter, Steffen; Lampenscherf, Stefan [Siemens AG, Corporate Technology, Otto-Hahn-Ring 6, 81730 München (Germany); Arnold, Thomas [Siemens Healthcare GmbH, Henkestr. 127, 91052 Erlangen (Germany)

2016-04-15

Highlights: • The tape casting process for tungsten is described. • A set-up of a HHF test facility for standing anodes is presented. • The thermo-cyclic behavior of tape cast tungsten and a reference is investigated. • The evolution of crack patterns is described in dependency of HHF-loadings. • The surface roughness of X-ray anodes is related to the microstructural evolution. - Abstract: This paper introduces tape casting as a new route for the production of isotropic and fine-grained tungsten components. Microstructural and thermal properties of tape cast tungsten samples are determined. Thermal shock behavior according to the thermo-cyclic loading of standing X-ray anodes is investigated and compared to the behavior of a rolled tungsten grade. The development of surface roughness during the thermal shock loading is discussed in relation to the development of the grain structure and crack pattern. The fine-grained and stable microstructure of the tape cast material exhibits less roughening under such test conditions.

Electrocatalysis on tungsten carbide

International Nuclear Information System (INIS)

Fleischmann, R.

1975-01-01

General concepts of electrocatalysis, the importance of the equilibrium rest potential and its standardization on polished WC-electrodes, the influence of oxygen in the catalysts upon the oxidation of hydrogen, and the attained results of the hydrogen oxidation on tungsten carbide are treated. (HK) [de

Experimental study of parallel multi-tungsten wire Z-pinch

International Nuclear Information System (INIS)

Huang Xianbin; China Academy of Engineering Physics, Mianyang; Lin Libin; Yang Libing; Deng Jianjun; Gu Yuanchao; Ye Shican; Yue Zhengpu; Zhou Shaotong; Li Fengping; Zhang Siqun

2005-01-01

The study of three parallel tungsten wire loads and five parallel tungsten wire loads implosion experiment on accelerator 'Yang' are reported. Tungsten wires (φ17 μm) with separation of 1 mm were used. The pinch was driven by a 350 kA peak current, 80 ns 10%-90% rise time. By means of pinhole camera and X-ray diagnostics technology, a non-uniform plasma column is formed among the wires and soft X-ray pulse are observed. the change of load current are analyzed, the development of sausage instability and kink instability, 'hot spot' effect and dispersion spot for plasma column are also discussed. (authors)

Loss of shear strength in polycrystalline tungsten under shock compression

International Nuclear Information System (INIS)

Dandekar, D.P.

1976-01-01

A reexamination of existing data on shock compression of polycrystalline tungsten at room temperature indicates that tungsten may be an exception to the common belief that metals do not behave like elastic-isotropic solids under shock compression

Archaeointensity study of five Late Bronze Age fireplaces from Corent (Auvergne, France)

OpenAIRE

Hervé , Gwenaël; Chauvin , Annick; Milcent , Pierre-Yves; Tramon , Arthur

2016-01-01

International audience; Recent excavations at Corent (France) unearthed a vast Late Bronze Age settlement. The high density of fireplaces especially highlights it. The present study focuses on the archaeomagnetic study of five fireplaces. These ones were dated between 950 and 800 BCE by cross-dating of metallic and ceramic artefacts and by radiocarbon. The main objective of our study is to increase the archaeointensity database in Western Europe at the beginning of the first millennium BCE. T...

Separation of Rhenium (VII) from Tungsten (VI)

International Nuclear Information System (INIS)

Vucina, J.; Lukic, D.; Stoiljkovic, M.; Milosevic, M.; Orlic, M.

2004-01-01

Examined were the conditions for an effective separation of tungsten (VI) and rhenium (VII) on alumina if the solution of 0.20 mol dm -3 NaCl, ph=2.6 is used as the aqueous phase. Under the given experimental conditions alumina was found to be much better adsorbent for tungsten than for rhenium. The breakthrough and saturation capacities of alumina at pH=2 are 24 and 78 mg W/g Al 2 O 3 , respectively. With the increase of pH these values decrease. So, at pH=6 they are only 4 and 13 mg W/g Al 2 O 3 respectively. The elution volume for rhenium for the given column dimensions and quantity of the adsorbent is about 16 ml. These results were confirmed by the experiments of the radiological separations. Tungsten-187 remains firmly bound to the alumina. The radionuclide purity of the eluted 186'188 Re at pH=2 is very high. (authors)

A supercritical carbon dioxide plasma process for preparing tungsten oxide nanowires

International Nuclear Information System (INIS)

Kawashima, Ayato; Nomura, Shinfuku; Toyota, Hiromichi; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro

2007-01-01

A supercritical carbon dioxide (CO 2 ) plasma process for fabricating one-dimensional tungsten oxide nanowires coated with amorphous carbon is presented. High-frequency plasma was generated in supercritical carbon dioxide at 20 MPa by using tungsten electrodes mounted in a supercritical cell, and subsequently an organic solvent was introduced with supercritical carbon dioxide into the plasma. Electron microscopy and Raman spectroscopy investigations of the deposited materials showed the production of tungsten oxide nanowires with or without an outer layer. The nanowires with an outer layer exhibited a coaxial structure with an outer concentric layer of amorphous carbon and an inner layer of tungsten oxide with a thickness and diameter of 20-30 and 10-20 nm, respectively

Deuterium Depth Profile in Neutron-Irradiated Tungsten Exposed to Plasma

International Nuclear Information System (INIS)

Shimada, Masashi; Cao, G.; Hatano, Y.; Oda, T.; Oya, Y.; Hara, M.; Calderoni, P.

2011-01-01

The effect of radiation damage has been mainly simulated using high-energy ion bombardment. The ions, however, are limited in range to only a few microns into the surface. Hence, some uncertainty remains about the increase of trapping at radiation damage produced by 14 MeV fusion neutrons, which penetrate much farther into the bulk material. With the Japan-US joint research project: Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), the tungsten samples (99.99 % pure from A.L.M.T., 6mm in diameter, 0.2mm in thickness) were irradiated to high flux neutrons at 50 C and to 0.025 dpa in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). Subsequently, the neutron-irradiated tungsten samples were exposed to a high-flux deuterium plasma (ion flux: 1021-1022 m-2s-1, ion fluence: 1025-1026 m-2) in the Tritium Plasma Experiment (TPE) at the Idaho National Laboratory (INL). First results of deuterium retention in neutron-irradiated tungsten exposed in TPE have been reported previously. This paper presents the latest results in our on-going work of deuterium depth profiling in neutron-irradiated tungsten via nuclear reaction analysis. The experimental data is compared with the result from non neutron-irradiated tungsten, and is analyzed with the Tritium Migration Analysis Program (TMAP) to elucidate the hydrogen isotope behavior such as retention and depth distribution in neutron-irradiated and non neutron-irradiated tungsten.

Development of tungsten coatings for the corrosion protection of alumina-based ceramics

International Nuclear Information System (INIS)

Arons, R.M.; Dusek, J.T.; Hafstrom, J.W.

1979-01-01

A means of applying tungsten coatings to an alumina based ceramic is described. A slurry of pure tungsten was prepared and applied by brush coating or slip casting on the alumina-3 wt % Yt small crucible. The composite was fired and a very dense ceramic crucible with a crack free tungsten coating was produced

Solar Orientations of Bronze Age Shrines in Gournia, Crete

Science.gov (United States)

Henriksson, G.; Blomberg, M.

2009-08-01

The measurements of orientations at Gournia are part of the Uppsala University project to investigate the nature of Minoan astronomy. The town is typical of Minoan settlements and therefore was chosen for the selection of representative buildings from different kinds of Minoan sites. We use classical archaeoastronomical methods and our own computer programs for calculation of the positions of the sun, moon and stars in the Aegean Bronze Age. We discovered that Gournia is the fourth Minoan site with shrines that are oriented to sunrise at lunar month intervals with respect to the equinoxes. There is also a Mycenaean shrine in the town and we compared its orientation to Mycenaean buildings of the same type in Crete.

Simulation of residual thermostress in tungsten after repetitive ELM-like heat loads

Energy Technology Data Exchange (ETDEWEB)

Pestchanyi, S., E-mail: serguei.pestchanyi@kit.edu [Karlsruhe Institute of Technology, IHM (Germany); Garkusha, I. [Institute of Plasma Physics of the NSC KIPT, Kharkov (Ukraine); Landman, I. [Karlsruhe Institute of Technology, IHM (Germany)

2011-10-15

Brittle destruction of tungsten armour under action of edge localised modes of plasma instabilities (ELMs) in ITER is an important issue determining the lifetime of the divertor. Besides, cracking of the armour produces tungsten dust with characteristic size of 1-10 {mu}m flying from the armour surface with velocities up to 10 m/s. Influx of the tungsten dust into the ITER confinement decreases the temperature of the plasma, reduces the thermonuclear gain and even may run the confinement into disruption. This paper describes experiments in QSPA-Kh50 plasma gun and modeling, which has been performed for providing more insight into the physics of tungsten cracking under action of ELMs and for confirmation of the important result on stabilization of the crack development at the tungsten armour surface, predicted in our previous paper - the same authors, 2010. The threshold value of energy density deposition for start of tungsten cracking has been measured as 0.3 MJ/m{sup 2} after 5-10 shots. From analytical considerations three times smaller threshold value has been predicted with increasing number of shots.

Simulation of residual thermostress in tungsten after repetitive ELM-like heat loads

International Nuclear Information System (INIS)

Pestchanyi, S.; Garkusha, I.; Landman, I.

2011-01-01

Brittle destruction of tungsten armour under action of edge localised modes of plasma instabilities (ELMs) in ITER is an important issue determining the lifetime of the divertor. Besides, cracking of the armour produces tungsten dust with characteristic size of 1-10 μm flying from the armour surface with velocities up to 10 m/s. Influx of the tungsten dust into the ITER confinement decreases the temperature of the plasma, reduces the thermonuclear gain and even may run the confinement into disruption. This paper describes experiments in QSPA-Kh50 plasma gun and modeling, which has been performed for providing more insight into the physics of tungsten cracking under action of ELMs and for confirmation of the important result on stabilization of the crack development at the tungsten armour surface, predicted in our previous paper - the same authors, 2010. The threshold value of energy density deposition for start of tungsten cracking has been measured as 0.3 MJ/m 2 after 5-10 shots. From analytical considerations three times smaller threshold value has been predicted with increasing number of shots.

Growth study and photocatalytic properties of Co-doped tungsten oxide mesocrystals

International Nuclear Information System (INIS)

Sun, Shibin; Chang, Xueting; Li, Zhenjiang

2012-01-01

Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer–Emmet–Teller analysis of nitrogen sorptometer, and UV–vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-doped tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: ► Co-doped W 18 O 49 mesocrystals were synthesized using a solvothermal method. ► The Co doping has obvious effect on the morphology of the final mesocrystals. ► The Co-doped W 18 O 49 exhibited superior photocatalytic activity to the undoped W 18 O 49 .

Spectroscopic modeling for tungsten EUV spectra

International Nuclear Information System (INIS)

Murakami, Izumi; Kato, Daiji; Sakaue, Hiroyuki A.; Suzuki, Chihiro; Morita, Shigeru; Goto, Motoshi; Sasaki, Akira; Nakamura, Nobuyuki; Yamamoto, Norimasa; Koike, Fumihiro

2014-01-01

We have constructed an atomic model for tungsten extreme ultraviolet (EUV) spectra to reconstruct characteristic spectral feature of unresolved transition array (UTA) observed at 4-7 nm for tungsten ions. In the tungsten atomic modeling, we considered fine-structure levels with the quantum principal number n up to 6 as the atomic structure and calculated the electron-impact collision cross sections by relativistic distorted-wave method, using HULLAC atomic code. We measured tungsten EUV spectra in Large Helical Device (LHD) and Compact Electron Beam Ion Trap device (CoBIT) and compared them with the model calculation. The model successfully explain series of emission peaks at 1.5-3.5 nm as n=5-4 and 6-4 transitions of W"2"4"+ - W"3"2"+ measured in CoBIT and LHD and the charge state distributions were estimated for LHD plasma. The UTA feature observed at 4-7 nm was also successfully reconstructed with our model. The peak at ∼5 nm is produced mainly by many 4f-4d transition of W"2"2"+ - W"3"5"+ ions, and the second peak at ∼6 nm is produced by 4f-4d transition of W"2"5"+ - W"2"8"+ ions, and 4d-4p inner-shell transitions, 4p"54d"n"+"1 - 4p"64d"n, of W"2"9"+ - W"3"5"+ ions. These 4d-4p inner-shell transitions become strong since we included higher excited states such as 4p"54d"n4f state, which ADAS atomic data set does not include for spectroscopic modeling with fine structure levels. (author)

Hydrogen and helium trapping in tungsten deposition layers formed by RF plasma sputtering

International Nuclear Information System (INIS)

Kazunari Katayama; Kazumi Imaoka; Takayuki Okamura; Masabumi Nishikawa

2006-01-01

Understanding of tritium behavior in plasma facing materials is an important issue for fusion reactor from viewpoints of fuel control and radiation safety. Tungsten is used as a plasma facing material in the divertor region of ITER. However, investigation of hydrogen isotope behavior in tungsten deposition layer is not sufficient so far. It is also necessary to evaluate an effect of helium on a formation of deposition layer and an accumulation of hydrogen isotopes because helium generated by fusion reaction exists in fusion plasma. In this study, tungsten deposition layers were formed by sputtering method using hydrogen and helium RF plasma. An erosion rate and a deposition rate of tungsten were estimated by weight measurement. Hydrogen and helium retention were investigated by thermal desorption method. Tungsten deposition was performed using a capacitively-coupled RF plasma device equipped with parallel-plate electrodes. A tungsten target was mounted on one electrode which is supplied with RF power at 200 W. Tungsten substrates were mounted on the other electrode which is at ground potential. The plasma discharge was continued for 120 hours where pressure of hydrogen or helium was controlled to be 10 Pa. The amounts of hydrogen and helium released from deposition layers was quantified by a gas chromatograph. The erosion rate of target tungsten under helium plasma was estimated to be 1.8 times larger than that under hydrogen plasma. The deposition rate on tungsten substrate under helium plasma was estimated to be 4.1 times larger than that under hydrogen plasma. Atomic ratio of hydrogen to tungsten in a deposition layer formed by hydrogen plasma was estimated to be 0.17 by heating to 600 o C. From a deposition layer formed by helium plasma, not only helium but also hydrogen was released by heating to 500 o C. Atomic ratios of helium and hydrogen to tungsten were estimated to be 0.080 and 0.075, respectively. The trapped hydrogen is probably impurity hydrogen

Superconductive materials. Structural mechanisms and nano-structures of some mixed skeletons oxides. Materiaux supraconducteurs. Mecanismes structuraux et nanostructures de quelques oxydes a charpentes mixtes

Energy Technology Data Exchange (ETDEWEB)

Hervieu, M [Caen Univ., 14 (France)

1993-12-01

Two families of superconductive crystals are described: the phosphate bronze of tungsten family [A[sub x](P[sub 2]O[sub 4])[sub 2](WO[sub 3])[sub 2m] or (PO[sub 2])[sub 4](WO[sub 3])[sub 2m] or A[sub x](PO[sub 2])[sub 4](WO[sub 3])[sub 2m

A Method to Make Classification of the Heat Treatment Processes Performed on Bronze Using Incomplete Knowledge

Directory of Open Access Journals (Sweden)

Kluska-Nawarecka S.

2014-06-01

Full Text Available The article describes the problem of selection of heat treatment parameters to obtain the required mechanical properties in heat- treated bronzes. A methodology for the construction of a classification model based on rough set theory is presented. A model of this type allows the construction of inference rules also in the case when our knowledge of the existing phenomena is incomplete, and this is situation commonly encountered when new materials enter the market. In the case of new test materials, such as the grade of bronze described in this article, we still lack full knowledge and the choice of heat treatment parameters is based on a fragmentary knowledge resulting from experimental studies. The measurement results can be useful in building of a model, this model, however, cannot be deterministic, but can only approximate the stochastic nature of phenomena. The use of rough set theory allows for efficient inference also in areas that are not yet fully explored.

Simulating evaporation of surface atoms of thorium-alloyed tungsten in strong electronic fields

International Nuclear Information System (INIS)

Bochkanov, P.V.; Mordyuk, V.S.; Ivanov, Yu.I.

1984-01-01

By the Monte Carlo method simulating evaporation of surface atoms of thorium - alloyed tungsten in strong electric fields is realized. The strongest evaporation of surface atoms of pure tungsten as compared with thorium-alloyed tungsten in the contentration range of thorium atoms in tungsten matrix (1.5-15%) is shown. The evaporation rate increases with thorium atoms concentration. Determined is in relative units the surface atoms evaporation rate depending on surface temperature and electric field stront

On the rational technology of low-grade tungsten raw material reprocessing

International Nuclear Information System (INIS)

Verevkin, G.V.; Kulmukhamedov, G.K.; Perlov, P.M.; Zelikman, A.N.; Ivanov, I.M.; Medvedev, V.V.

1989-01-01

The most rational technology for autoclave alkali reprocessing is presented. It lies in selective extraction of tungsten from alkali, containing the excess soda. It is shown that deep purification of tungsten from silicon, phosphorus and arsenic impurities takes place during tungsten extraction out of alkaline media. The important advantage of alkaline extraction technology is the exclusion of acid usage, possibility of soda regeneration and liquidation of acid flows, which solves the ecological problems

Ion cyclotron resonance heating for tungsten control in various JET H-mode scenarios

Science.gov (United States)

Goniche, M.; Dumont, R. J.; Bobkov, V.; Buratti, P.; Brezinsek, S.; Challis, C.; Colas, L.; Czarnecka, A.; Drewelow, P.; Fedorczak, N.; Garcia, J.; Giroud, C.; Graham, M.; Graves, J. P.; Hobirk, J.; Jacquet, P.; Lerche, E.; Mantica, P.; Monakhov, I.; Monier-Garbet, P.; Nave, M. F. F.; Noble, C.; Nunes, I.; Pütterich, T.; Rimini, F.; Sertoli, M.; Valisa, M.; Van Eester, D.; Contributors, JET

2017-05-01

Ion cyclotron resonance heating (ICRH) in the hydrogen minority scheme provides central ion heating and acts favorably on the core tungsten transport. Full wave modeling shows that, at medium power level (4 MW), after collisional redistribution, the ratio of power transferred to the ions and the electrons vary little with the minority (hydrogen) concentration n H/n e but the high-Z impurity screening provided by the fast ions temperature increases with the concentration. The power radiated by tungsten in the core of the JET discharges has been analyzed on a large database covering the 2013-2014 campaign. In the baseline scenario with moderate plasma current (I p = 2.5 MA) ICRH modifies efficiently tungsten transport to avoid its accumulation in the plasma centre and, when the ICRH power is increased, the tungsten radiation peaking evolves as predicted by the neo-classical theory. At higher current (3-4 MA), tungsten accumulation can be only avoided with 5 MW of ICRH power with high gas injection rate. For discharges in the hybrid scenario, the strong initial peaking of the density leads to strong tungsten accumulation. When this initial density peaking is slightly reduced, with an ICRH power in excess of 4 MW,very low tungsten concentration in the core (˜10-5) is maintained for 3 s. MHD activity plays a key role in tungsten transport and modulation of the tungsten radiation during a sawtooth cycle is correlated to the fishbone activity triggered by the fast ion pressure gradient.

Physical mechanisms related to the degradation of LPCVD tungsten contacts at elevated temperatures

International Nuclear Information System (INIS)

Shenai, K.; Lewis, N.; Smith, G.A.; McConnell, M.D.; Burrell, M.

1990-01-01

The thermal stability of LPCVD (low pressure chemical vapor deposition) tungsten contacts to n-type silicon is studied at elevated temperatures in excess of 650 degrees C. The process variants studied include silicon doping, tungsten thickness, and post tungsten deposition dielectric stress temperatures. Detailed measurements of Kelvin contact resistance were made at room temperature as well as at elevated temperatures up to 165 degrees C. The tungsten contact resistance degradation at elevated stress temperatures is correlated with worm hole formation in silicon and the formation and diffusion of tungsten silicide. Extensive analytical measurements were used to characterize the material transformation at elevated stress temperatures to understand the physical mechanisms causing contact degradation

TIG (Tungsten Inert Gas) welding

International Nuclear Information System (INIS)

Anon.

2010-01-01

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.)

Tungsten migration studies by controlled injection of volatile compounds

Energy Technology Data Exchange (ETDEWEB)

Rubel, M., E-mail: rubel@kth.se [Royal Institute of Technology (KTH), Association EURATOM-VR, Stockholm (Sweden); Coenen, J. [IEK-4, Plasma Physics, Forschungszentrum Jülich, Association EURATOM-FZJ, Jülich (Germany); Ivanova, D. [Royal Institute of Technology (KTH), Association EURATOM-VR, Stockholm (Sweden); Möller, S. [IEK-4, Plasma Physics, Forschungszentrum Jülich, Association EURATOM-FZJ, Jülich (Germany); Petersson, P. [Royal Institute of Technology (KTH), Association EURATOM-VR, Stockholm (Sweden); Brezinsek, S.; Kreter, A.; Philipps, V.; Pospieszczyk, A.; Schweer, B. [IEK-4, Plasma Physics, Forschungszentrum Jülich, Association EURATOM-FZJ, Jülich (Germany)

2013-07-15

Volatile tungsten hexa-fluoride was locally injected into the TEXTOR tokamak as a marker for material migration studies. The injection was accompanied by puffing N-15 rare isotope as a nitrogen tracer in discharges with edge cooling by impurity seeding. The objective was to assess material balance by qualitative and quantitative determination of a global and local deposition pattern, material mixing effects and fluorine residence in plasma-facing components. Spectroscopy and ex situ ion beam analysis techniques were used. Tungsten was detected on all types of limiter tiles and short-term probes retrieved from the vessel. Over 80% of the injected W was identified. The largest tungsten concentration, 1 × 10{sup 18} cm{sup −2}, was in the vicinity of the gas inlet. Co-deposits contained tungsten and a mix of light isotopes: H, D, He-4, B-10, B-11, C-12, C-13, N-14, N-15, O-16 and small quantities of F-19 thus showing that both He and nitrogen are trapped following wall conditioning (He glow) and edge cooling.

Fabrication of tungsten probe for hard tapping operation in atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Han, Guebum, E-mail: hanguebum@live.co.kr [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, Indiana 47803 (United States); Department of Mechanical Design and Robot Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 139-743 (Korea, Republic of); Ahn, Hyo-Sok, E-mail: hsahn@seoultech.ac.kr [Manufacturing Systems and Design Engineering Programme, Seoul National University of Science & Technology, 232 Gongneung-ro, Nowon-gu, Seoul 139-743 (Korea, Republic of)

2016-02-15

We propose a method of producing a tungsten probe with high stiffness for atomic force microscopy (AFM) in order to acquire enhanced phase contrast images and efficiently perform lithography. A tungsten probe with a tip radius between 20 nm and 50 nm was fabricated using electrochemical etching optimized by applying pulse waves at different voltages. The spring constant of the tungsten probe was determined by finite element analysis (FEA), and its applicability as an AFM probe was evaluated by obtaining topography and phase contrast images of a Si wafer sample partly coated with Au. Enhanced hard tapping performance of the tungsten probe compared with a commercial Si probe was confirmed by conducting hard tapping tests at five different oscillation amplitudes on single layer graphene grown by chemical vapor deposition (CVD). To analyze the damaged graphene sample, the test areas were investigated using tip-enhanced Raman spectroscopy (TERS). The test results demonstrate that the tungsten probe with high stiffness was capable of inducing sufficient elastic and plastic deformation to enable obtaining enhanced phase contrast images and performing lithography, respectively. - Highlights: • We propose a method of producing highly stiff tungsten probes for hard tapping AFM. • Spring constant of tungsten probe is determined by finite element method. • Enhanced hard tapping performance is confirmed. • Tip-enhanced Raman spectroscopy is used to identify damage to graphene.

Fabrication of tungsten probe for hard tapping operation in atomic force microscopy

International Nuclear Information System (INIS)

Han, Guebum; Ahn, Hyo-Sok

2016-01-01

We propose a method of producing a tungsten probe with high stiffness for atomic force microscopy (AFM) in order to acquire enhanced phase contrast images and efficiently perform lithography. A tungsten probe with a tip radius between 20 nm and 50 nm was fabricated using electrochemical etching optimized by applying pulse waves at different voltages. The spring constant of the tungsten probe was determined by finite element analysis (FEA), and its applicability as an AFM probe was evaluated by obtaining topography and phase contrast images of a Si wafer sample partly coated with Au. Enhanced hard tapping performance of the tungsten probe compared with a commercial Si probe was confirmed by conducting hard tapping tests at five different oscillation amplitudes on single layer graphene grown by chemical vapor deposition (CVD). To analyze the damaged graphene sample, the test areas were investigated using tip-enhanced Raman spectroscopy (TERS). The test results demonstrate that the tungsten probe with high stiffness was capable of inducing sufficient elastic and plastic deformation to enable obtaining enhanced phase contrast images and performing lithography, respectively. - Highlights: • We propose a method of producing highly stiff tungsten probes for hard tapping AFM. • Spring constant of tungsten probe is determined by finite element method. • Enhanced hard tapping performance is confirmed. • Tip-enhanced Raman spectroscopy is used to identify damage to graphene.

$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...

Ductile tungsten-nickel alloy and method for making same

Science.gov (United States)

Snyder, Jr., William B.

1976-01-01

The present invention is directed to a ductile, high-density tungsten-nickel alloy which possesses a tensile strength in the range of 100,000 to 140,000 psi and a tensile elongation of 3.1 to 16.5 percent in 1 inch at 25.degree.C. This alloy is prepared by the steps of liquid phase sintering a mixture of tungsten-0.5 to 10.0 weight percent nickel, heat treating the alloy at a temperature above the ordering temperature of approximately 970.degree.C. to stabilize the matrix phase, and thereafter rapidly quenching the alloy in a suitable liquid to maintain the matrix phase in a metastable, face-centered cubic, solid- solution of tungsten in nickel.

Erosion and migration of tungsten employed at the central column heat shield of ASDEX Upgrade

International Nuclear Information System (INIS)

Krieger, K.; Gong, X.; Balden, M.; Hildebrandt, D.; Maier, H.; Rohde, V.; Roth, J.; Schneider, W.

2002-01-01

In ASDEX Upgrade, tungsten was employed as plasma facing material at the central column heat shield in the plasma main chamber. The campaign averaged tungsten erosion flux was determined by measuring the difference of the W-layer thickness before and after the experimental campaign using ion beam analysis methods. The observed lateral variation and the total amount of eroded tungsten are attributed to erosion by impact of ions from the scrape-off layer plasma. Migration and redeposition of eroded tungsten were investigated by quantitative analysis of deposited tungsten on collector probes and wall samples. The obtained results, as well as the spectroscopically observed low tungsten plasma penetration probability, indicate that a major fraction of the eroded tungsten migrates predominantly through direct transport channels in the outer plasma scrape-off layer without entering the confined plasma

Investigation of composition of the products of thermal processing of tungsten concentrate

International Nuclear Information System (INIS)

Sokol, I.V.; Krasnova, T.V.

1994-01-01

The composition of the products of carbidization of tungsten concentrate has been investigated. A method ha sbeen developed for chemcial phase analysis of multicomponent powders based on tungsten carbides. The prepared powders have been used for the manufacture of electrode tools based on a tungsten-copper preudoalloy, which can be for dimensional electroerosion treatment of hard alloys and electrodes for electric-spark alloying

Tungsten oxide nanowires grown on graphene oxide sheets as high-performance electrochromic material

International Nuclear Information System (INIS)

Chang, Xueting; Sun, Shibin; Dong, Lihua; Hu, Xiong; Yin, Yansheng

2014-01-01

Graphical abstract: Electrochromic mechanism of tungsten oxide nanowires-reduced graphene oxide composite. - Highlights: • A novel inorganic-nano-carbon hybrid composite was prepared. • The hybrid composite has sandwich-like structure. • The hybrid composite exhibited high-quality electrohcromic performance. - Abstract: In this work, we report the synthesis of a novel hybrid electrochromic composite through nucleation and growth of ultrathin tungsten oxide nanowires on graphene oxide sheets using a facile solvothermal route. The competition between the growth of tungsten oxide nanowires and the reduction of graphene oxide sheets leads to the formation of sandwich-structured tungsten oxide-reduced graphene oxide composite. Due to the strongly coupled effect between the ultrathin tungsten oxide nanowires and the reduced graphene oxide nanosheets, the novel electrochromic composite exhibited high-quality electrochromic performance with fast color-switching speed, good cyclic stability, and high coloration efficiency. The present tungsten oxide-reduced graphene oxide composite represents a new approach to prepare other inorganic-reduced graphene oxide hybrid materials for electrochemical applications

Tissue distribution patterns of solubilized metals from internalized tungsten alloy in the F344 rat

Directory of Open Access Journals (Sweden)

Vernieda B. Vergara

2016-06-01

Full Text Available Because of its unique physical and chemical properties, tungsten has been increasingly utilized in a variety of civilian and military applications. This expanded use also raises the risk of human exposure through internalization by various routes. In most cases the toxicological and carcinogenic properties of these tungsten-based compounds are not known nor are the dissolution biokinetics and ultimate fate of the associated metals. Using a laboratory rodent model system designed to assess the health effects of embedded metals, and a tungsten alloy comprised of tungsten (91.1%, nickel (6.0%, and cobalt (2.9%, we investigated the tissue distribution patterns of the metals over a six month period. Despite its perceived insolubility, tungsten rapidly solubilized from the implanted metal fragments, as did nickel and cobalt. All three metals distributed systemically over time with extremely elevated levels of all three metals found in kidney, liver, and spleen. Unexpectedly, tungsten was found to cross the blood-brain and blood-testis barriers and localize in those tissues. These results, along with recent reports suggesting that tungsten is a tumor promoter, raises serious concerns as to the long-term health effects of exposure to tungsten and tungsten-based compounds.

Genetic characteristics and migration history of a bronze culture population in the West Liao-River valley revealed by ancient DNA.

Science.gov (United States)

Li, Hongjie; Zhao, Xin; Zhao, Yongbin; Li, Chunxiang; Si, Dayong; Zhou, Hui; Cui, Yinqiu

2011-12-01

In order to study the genetic characteristics of the Lower Xiajiadian culture (LXC) population, a main bronze culture branch in northern China dated 4500-3500 years ago, two uniparentally inherited markers, mitochondrial DNA and Y-chromosome single-nucleotide polymorphisms (Y-SNPs), were analyzed on 14 human remains excavated from the Dadianzi site. The 14 sequences, which contained 13 haplotypes, were assigned to 9 haplogroups, and Y-SNP typing of 5 male individuals assigned them to haplogroups N (M231) and O3 (M122). The results indicate that the LXC population mainly included people carrying haplogroups from northern Asia who had lived in this region since the Neolithic period, as well as genetic evidence of immigration from the Central Plain. Later in the Bronze Age, part of the population migrated to the south away from a cooler climate, which ultimately influenced the gene pool in the Central Plain. Thus, climate change is an important factor, which drove the population migration during the Bronze Age in northern China. Based on these results, the local genetic continuity did not seem to be affected by outward migration, although more data are needed especially from other ancient populations to determine the influence of return migration on genetic continuity.

Controlled tungsten melting and droplet ejection studies in ASDEX Upgrade

International Nuclear Information System (INIS)

Krieger, K; Lunt, T; Dux, R; Janzer, A; Müller, H W; Potzel, S; Pütterich, T; Yang, Z

2011-01-01

Tungsten rods of 1×1×3 mm 3 were exposed in single H-mode discharges at the outer divertor target plate of ASDEX Upgrade using the divertor manipulator system. Melting of the W rod at a pre-defined time was induced by moving the initially far away outer strike point close to the W-rod position. Visible light emissions of both the W pin and consecutively ejected W droplets were recorded by two fast cameras with crossed viewing cones. The time evolution of the local W source at the pin location was measured by spectroscopic observation of the WI line emission at 400.9 nm and compared to the subsequent increase of tungsten concentration in the confined plasma derived from tungsten vacuum UV line emission. Combining these measurements with the total amount of released tungsten due to the pin melt events and ejected droplets allowed us to derive an estimate of the screening factor for this type of tungsten source. The resulting values of the tungsten divertor retention in the range 10-20 agree with those found in previous studies using a W source of sublimated W(CO) 6 vapour at the same exposure location. Ejected droplets were found to be always accelerated in the general direction of the plasma flow, attributed to friction forces and to rocket forces. Furthermore, the vertically inclined target plates cause the droplets, which are repelled by the target plate surface potential due to their electric charge, to move upwards against gravity due to the centrifugal force component parallel to the target plate.

Thermal response of plasma sprayed tungsten coating to high heat flux

International Nuclear Information System (INIS)

Liu, X.; Yang, L.; Tamura, S.; Tokunaga, K.; Yoshida, N.; Noda, N.; Xu, Z.

2004-01-01

In order to investigate the thermal response of tungsten coating on carbon and copper substrates by vacuum plasma spray (VPS) or inert gas plasma spray (IPS), annealing and cyclic heat load experiments of these coatings were conducted. It is indicated that the multi-layered tungsten and rhenium interface of VPS-W/CFC failed to act as a diffusion barrier at elevated temperature and tungsten carbides were developed after 1 h incubation time when annealing temperature was higher than 1600 deg. C. IPS-W/Cu and W/C without an intermediate bonding layer were failed by the detachment of the tungsten coating at 900 and 1200 deg. C annealing for several hours, respectively. Cyclic heat load of electron beam with 35 MW/m 2 and 3-s pulse duration indicated that IPS-W/Cu samples failed with local detachment of the tungsten coating within 200 cycles and IPS-W/C showed local cracks by 300 cycles, but VPS-W/CFC withstood 1000 cycles without visible damages. However, crack creation and propagation in VPS-W/CFC were also observed under higher heat load

Monumental megalithic burial and rock art tell a new story about the Levant Intermediate Bronze "Dark Ages".

Science.gov (United States)

Sharon, Gonen; Barash, Alon; Eisenberg-Degen, Davida; Grosman, Leore; Oron, Maya; Berger, Uri

2017-01-01

The Intermediate Bronze Age (IB) in the Southern Levant (ca. 2350-2000 BCE) is known as the "Dark Ages," following the collapse of Early Bronze urban society and predating the establishment of the Middle Bronze cities. The absence of significant settlements and monumental building has led to the reconstruction of IB social organization as that of nomadic, tribal society inhabiting rural villages with no central governmental system. Excavation in the Shamir Dolmen Field (comprising over 400 dolmens) on the western foothills of the Golan Heights was carried out following the discovery of rock art engravings on the ceiling of the central chamber inside one of the largest dolmens ever recorded in the Levant. Excavation of this multi-chambered dolmen, covered by a basalt capstone weighing some 50 tons, revealed a secondary multi-burial (of both adults and children) rarely described in a dolmen context in the Golan. Engraved into the rock ceiling above the multi-burial is a panel of 14 forms composed of a vertical line and downturned arc motif. 3D-scanning by structured-light technology was used to sharpen the forms and revealed the technique employed to create them. Building of the Shamir dolmens required a tremendous amount of labor, architectural mastery, and complex socio-economic organization well beyond the capacity of small, rural nomadic groups. The monumental megalithic burial of the Shamir dolmens indicates a hierarchical, complex, non-urban governmental system. This new evidence supports a growing body of recent criticism stemming from new discoveries and approaches that calls for rethinking our views of the Levantine IB "Dark Ages."

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

Thermal shock behaviour of different tungsten grades under varying conditions

International Nuclear Information System (INIS)

Wirtz, Oliver Marius

2012-01-01

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 -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 damages

Granite-related Yangjiashan tungsten deposit, southern China

Science.gov (United States)

Xie, Guiqing; Mao, Jingwen; Li, Wei; Fu, Bin; Zhang, Zhiyuan

2018-04-01

The Yangjiashan scheelite-bearing deposit (38,663 metric tons of WO3 with an average ore grade of 0.70% WO3) is hosted in quartz veins in a biotite monzogranite intrusion and surrounding slate in the Xiangzhong Metallogenic Province of southern China. The monzogranite has a zircon SHRIMP U-Pb age of 406.6 ± 2.8 Ma (2σ, n = 20, MSWD = 1.4). Cassiterite coexisting with scheelite yields a weighted mean 206Pb/238U age of 409.8 ± 5.9 Ma (2σ, n = 30, MSWD = 0.20), and molybdenite intergrown with scheelite yields a weighted mean Re-Os age of 404.2 ± 3.2 Ma (2σ, n = 3, MSWD = 0.10). These results suggest that the Yangjiashan tungsten deposit is temporally related to the Devonian intrusion. The δD and calculated δ18OH2O values of quartz intergrown with scheelite range from - 87 to - 68‰, and - 1.2 to 3.4‰, respectively. Sulfides have a narrow range of δ34S values of - 2.9 to - 0.7‰ with an average value of - 1.6‰ (n = 16). The integration of geological, stable isotope, and geochronological data, combined with the quartz-muscovite greisen style of ore, supports a magmatic-hydrothermal origin for the tungsten mineralization. Compared to the more common tungsten skarn, quartz-wolframite vein, and porphyry tungsten deposits, as well as orogenic gold deposits worldwide, the Yangjiashan tungsten deposit is an unusual example of a granite-related, gold-poor, scheelite-bearing quartz vein type of deposit. The calcium needed for the formation of scheelite is derived from the sericitization of calcic plagioclase in the monzogranite and Ca-bearing psammitic country rocks, and the relatively high pH, reduced and Ca-rich mineralizing fluid may be the main reasons for the formation of scheelite rather than wolframite at Yangjiashan.

Social change in ‘Phoenicia’ in the late Bronze/early Iron Age transition

OpenAIRE

Boyes, Philip

2013-01-01

This dissertation explores social, cultural and political changes in the region later known as ‘Phoenicia’ during the period of approximately 1300-900 BC. By applying modern approaches to theoretical questions such as the nature of social change, identity, migration and how such phenomena are represented in the archaeological record, this dissertation aims to provide a discussion of Late Bronze/Early Iron Age Phoenicia based on a more solid methodological foundation than has of...

Comparison of deuterium retention for ion-irradiated and neutron-irradiated tungsten

International Nuclear Information System (INIS)

Oya, Yasuhisa; Kobayashi, Makoto; Okuno, Kenji; Shimada, Masashi; Calderoni, Pattrick; Oda, Takuji; Hara, Masanori; Hatano, Yuji; Watanabe, Hideo

2014-01-01

The behavior of D retentions for Fe 2+ irradiated tungsten with the damage of 0.025-3 dpa was compared with that for neutron irradiated tungsten with 0.025 dpa. The D 2 TDS spectra for Fe 2+ irradiated tungsten consisted of two desorption stages at 450 K and 550 K although that for neutron irradiated tungsten was composed of three stages and addition desorption stage was found around 750 K. The desorption rate of major desorption stage at 550 K increased as the number of dpa by Fe 2+ irradiation increased. In addition, the first desorption stage at 450 K was only found for the damaged samples, indicating that the second stage would be based on intrinsic defects or vacancy produced by Fe 2+ irradiation and the first stage should be the accumulation of D in mono vacancy leading to the lower activation energy, where the dislocation loop and vacancy was produced. The third one was only found for the neutron irradiation, showing the D trapping by void or vacancy cluster and the diffusion effect is also contributed due to high FWHM of TDS spectrum. It can be said that the D 2 TDS spectra for Fe 2+ -irradiated tungsten could not represent that for neutron-irradiated one, showing that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten has a difference from that for ion-irradiated one. (author)

Growth study and photocatalytic properties of Co-doped tungsten oxide mesocrystals

Energy Technology Data Exchange (ETDEWEB)

Sun, Shibin [College of Logistics Engineering, Shanghai Maritime University, Shanghai 200135 (China); College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Chang, Xueting, E-mail: xuetingchang@yahoo.cn [College of Logistics Engineering, Shanghai Maritime University, Shanghai 200135 (China); Li, Zhenjiang [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China)

2012-11-15

Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmet-Teller analysis of nitrogen sorptometer, and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-doped tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: Black-Right-Pointing-Pointer Co-doped W{sub 18}O{sub 49} mesocrystals were synthesized using a solvothermal method. Black-Right-Pointing-Pointer The Co doping has obvious effect on the morphology of the final mesocrystals. Black-Right-Pointing-Pointer The Co-doped W{sub 18}O{sub 49} exhibited superior photocatalytic activity to the undoped W{sub 18}O{sub 49}.

Two component tungsten powder injection molding – An effective mass production process

International Nuclear Information System (INIS)

Antusch, Steffen; Commin, Lorelei; Mueller, Marcus; Piotter, Volker; Weingaertner, Tobias

2014-01-01

Tungsten and tungsten-alloys are presently considered to be the most promising materials for plasma facing components for future fusion power plants. The Karlsruhe Institute of Technology (KIT) divertor design concept for the future DEMO power plant is based on modular He-cooled finger units and the development of suitable mass production methods for such parts was needed. A time and cost effective near-net-shape forming process with the advantage of shape complexity, material utilization and high final density is Powder Injection Molding (PIM). This process allows also the joining of two different materials e.g. tungsten with a doped tungsten alloy, without brazing. The complete technological process of 2-Component powder injection molding for tungsten materials and its application on producing real DEMO divertor parts, characterization results of the finished parts e.g. microstructure, hardness, density and joining zone quality are discussed in this contribution