Properties of tungsten coating deposited onto copper by high-speed atmospheric plasma spraying

Energy Technology Data Exchange (ETDEWEB)

Huang Jianjun, E-mail: huangjj@szu.edu.cn [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Wang Fan; Liu Ying; Jiang Shishou; Wang Xisheng; Qi Bing; Gao Liang [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China)

2011-07-01

Tungsten (W) coatings were fabricated on copper (Cu) by high-speed atmospheric plasma spray (HAPS) technique. The properties of the porosity, oxygen content, bonding strength and microhardness were measured. The results obtained indicated that the HAPS-W coating showed good properties particularly in terms of porosity and oxygen content. The porosity of the HAPS-W coating was 2.3% and the distribution of pore size diameter was mainly concentrated in the range of 0.01-1 {mu}m. The oxygen content of the coating measured by means of Nitrogen/Oxygen Determinator was about 0.10 wt.%. These initial results suggest that the HAPS-W coating has achieved the reported properties of the vacuum plasma spray (VPS) W coating. Compared with VPS, HAPS-W technique could provide a convenient and low cost way to obtain adequate W coatings for fusion applications.

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.

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

Label-free tungsten disulfide quantum dots as a fluorescent sensing platform for highly efficient detection of copper (II) ions

International Nuclear Information System (INIS)

Zhao Xuan; He Da-Wei; Wang Yong-Sheng; Hu Yin; Fu Chen; Li Xue

2017-01-01

A fluorescent probe for the sensitive and selective determination of copper ion (Cu 2+ ) is presented. It is based on the use of tungsten disulfide quantum dots (WS 2 QDs) which is independent of the pH of solution and emits strong blue fluorescence. Copper ions could cause aggregation of the WS 2 QDs and lead to fluorescence quenching of WS 2 QDs. The change of fluorescence intensity is proportional to the concentration of Cu 2+ , and the limit of detection is 0.4 μM. The fluorescent probe is highly selective for Cu 2+ over some potentially interfering ions. These results indicate that WS 2 QDs, as a fluorescent sensing platform, can meet the selective requirements for biomedical and environmental application. (paper)

Optimization of armour geometry and bonding techniques for tungsten-armoured high heat flux components

International Nuclear Information System (INIS)

Giniyatulin, R.N.; Komarov, V.L.; Kuzmin, E.G.; Makhankov, A.N.; Mazul, I.V.; Yablokov, N.A.; Zhuk, A.N.

2002-01-01

Joining of tungsten with copper-based cooling structure and armour geometry optimization are the major aspects in development of the tungsten-armoured plasma facing components (PFC). Fabrication techniques and high heat flux (HHF) tests of tungsten-armoured components have to reflect different PFC designs and acceptable manufacturing cost. The authors present the recent results of tungsten-armoured mock-ups development based on manufacturing and HHF tests. Two aspects were investigated--selection of armour geometry and examination of tungsten-copper bonding techniques. Brazing and casting tungsten-copper bonding techniques were used in small mock-ups. The mock-ups with armour tiles (20x5x10, 10x10x10, 20x20x10, 27x27x10) mm 3 in dimensions were tested by cyclic heat fluxes in the range of (5-20) MW/m 2 , the number of thermal cycles varied from hundreds to several thousands for each mock-up. The results of the tests show the applicability of different geometry and different bonding technique to corresponding heat loading. A medium-scale mock-up 0.6-m in length was manufactured and tested. HHF tests of the medium-scale mock-up have demonstrated the applicability of the applied bonding techniques and armour geometry for full-scale PFC's manufacturing

Release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms

International Nuclear Information System (INIS)

Thomas, Vernon G.; Santore, Robert C.; McGill, Ian

2007-01-01

Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p values < 0.000). The rate of copper release from tungsten bronze shot was 30 to 50 times lower than that from the copper shot, depending on pH (p < 0.0000). The observed expected environmental concentration of copper released from tungsten-bronze shot after 28 days was 0.02 μg/L at pH 7.8, and 0.4 μg/L at pH 5.6, using a loading and exposure scenario specific in a U.S. Fish and Wildlife Service protocol. Ratio Quotient values derived from the highest EEC observed in this study (0.4 μg/L), and the copper toxic effect levels for all aquatic species listed in the U.S. Environmental Protection Agency ambient water quality criteria database, were all far less than the 0.1 criterion value. Given the conditions stipulated by the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency, heavy loading from discharged tungsten-bronze shot would not pose a toxic risk to potable water, or to soil. Consequently, it would appear that no toxic risks to aquatic organisms will attend the use of tungsten-bronze shot of the approved composition. Given the likelihood that sintered tungsten-bronze of the same formula will be used for fishing weights, bullets, and wheel balance weights, it is

High density tungsten-nickel-iron-cobalt alloys having improved hardness and method for making same

International Nuclear Information System (INIS)

Penrice, T.W.; Bost, J.

1988-01-01

This patent describes the process of making high density alloy containing about 85 to 98 weight percent tungsten and the balance of the alloy being essentially a binder of nickel, iron and cobalt, and wherein the cobalt is present in an amount within the range of about 5 to 47.5 weight percent of the binder, comprising: blending powders of the tungsten, nickel, iron and cobalt into a homogeneous composition, compacting the homogeneous composition into a shaped article, heating the shaped article to a temperature and for a time sufficient to sinter the article, subjecting the sintered article to a temperature sufficient to enable the intermetallic phase formed at the matrix to tungsten interface to diffuse into the gamma austenitic phase whereby the alpha tungsten/gamma austenite boundaries are essentially free of such intermetallic phase, quenching the article, and swaging the article to a reduction in area of about 5 to 40 percent, the article having improved mechanical properties, including improved tensile strength and hardness while maintaining suitable ductility for subsequent working thereof

Controlling fundamentals in high-energy high-rate pulsed power materials processing of powdered tungsten, titanium aluminides, and copper-graphite composites. Final technical report, 1 Jun 87-31 Aug 90

Energy Technology Data Exchange (ETDEWEB)

Persad, C.; Marcus, H.L.; Bourell, D.L.; Eliezer, Z.; Weldon, W.F.

1990-10-01

This study was conducted to determine the controlling fundamentals in the high-energy high-rate (1 MJ in 1s) processing of metal powders. This processing utilizes a large electrical current pulse to heat a pressurized powder mass. The current pulse was provided by a homopolar generator. Simple short cylindrical shapes were consolidated so as to minimize tooling costs. Powders were subjected to current densities of 5 kA/cm2 to 25 kA/cm2 under applied pressures ranging from 70 MPa to 500 MPa. Disks with diameters of 25 mm to 70 mm, and thicknesses of 1 mm to 10 mm were consolidated. Densities of 75% to 99% of theoretical values were obtained in powder consolidates of tungsten, titanium aluminides, copper-graphite, and other metal-ceramic composites. Extensive microstructural characterization was performed to follow the changes occuring in the shape and microstructure of the various powders. The processing science has at its foundation the control of the duration of elevated temperature exposure during powder consolidation.

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

International Nuclear Information System (INIS)

Nilsson, J.O.; Wilson, A.; Huhtala, T.; Karlsson, L.; Jonsson, P.

1996-01-01

Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 C to 1,110 C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ 2 ) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ 2 compared with primary austenite. The volume fraction of γ 2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ 2 in these

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

Science.gov (United States)

Nilsson, J.-O.; Huhtala, T.; Jonsson, P.; Karlsson, L.; Wilson, A.

1996-08-01

Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 °C to 1110 °C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ2) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ2 compared with primary austenite. The volume fraction of γ2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ2 in these.

Studies on transport properties of copper doped tungsten diselenide single crystals

Science.gov (United States)

Deshpande, M. P.; Parmar, M. N.; Pandya, Nilesh N.; Chaki, Sunil; Bhatt, Sandip V.

2012-02-01

During recent years, transition metal dichalcogenides of groups IVB, VB and VIB have received considerable attention because of the great diversity in their transport properties. 2H-WSe 2 (Tungsten diselenide) is an interesting member of the transition metal dichalcogenide (TMDC's) family and known to be a semiconductor useful for photovoltaic and optoelectronic applications. The anisotropy usually observed in this diamagnetic semiconductor material is a result of the sandwich structure of Se-W-Se layers interacting with each other, loosely bonded by the weak Van der Waals forces. Recent efforts in studying the influence of the anisotropic electrical and optical properties of this layered-type transition metal dichalcogenides have been implemented by doping the samples with different alkali group elements. Unfortunately, little work is reported on doping of metals in WSe 2. Therefore, it is proposed in this work to carry out a systematic growth of single crystals of WSe 2 by doping it with copper in different proportions i.e. Cu xWSe 2 ( x=0, 0.5, 1.0) by direct vapour transport technique. Transport properties like low and high temperature resistivity measurements, high pressure resistivity, Seebeck coefficient measurements at low temperature and Hall Effect at room temperature were studied in detail on all these samples. These measurements show that tungsten diselenide single crystals are p-type whereas doped with copper makes it n-type in nature. The results obtained and their implications are discussed in this paper.

Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

Science.gov (United States)

Riccardi, B.; Montanari, R.; Casadei, M.; Costanza, G.; Filacchioni, G.; Moriani, A.

2006-06-01

Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component.

Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

International Nuclear Information System (INIS)

Riccardi, B.; Montanari, R.; Casadei, M.; Costanza, G.; Filacchioni, G.; Moriani, A.

2006-01-01

Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component

Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

Energy Technology Data Exchange (ETDEWEB)

Riccardi, B. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, P.B. 65 00044 Frascati, Roma (Italy)]. E-mail: riccardi@frascati.enea.it; Montanari, R. [Dipartimento di Ingegneria Meccanica, Universita di Roma, Tor Vergata, 00133 Roma (Italy); Casadei, M. [Centro Sviluppo Materiali, 00100 Roma (Italy); Costanza, G. [Dipartimento di Ingegneria Meccanica, Universita di Roma, Tor Vergata, 00133 Roma (Italy); Filacchioni, G. [ENEA CR Casaccia, I-00060 S. M. di Galeria, Roma (Italy); Moriani, A. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, P.B. 65 00044 Frascati, Roma (Italy)

2006-06-30

Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component.

Effect of electrolysis parameters on the morphologies of copper powder obtained at high current densities

Directory of Open Access Journals (Sweden)

Orhan Gökhan

2012-01-01

Full Text Available The effects of copper ion concentrations and electrolyte temperature on the morphologies and on the apparent densities of electrolytic copper powders at high current densities under galvanostatic regime were examined. These parameters were evaluated by the current efficiency of hydrogen evolution. In addition, scanning electron microscopy was used for analyzing the morphology of the copper powders. It was found that the morphology was dependent over the copper ion concentration and electrolyte temperature under same current density (CD conditions. At 150 mA cm-2 and the potential of 1000±20 mV (vs. SCE, porous and disperse copper powders were obtained at low concentrations of Cu ions (0.120 M Cu2+ in 0.50 M H2SO4. Under this condition, high rate of hydrogen evolution reaction took place parallel to copper electrodeposition. The morphology was changed from porous, disperse and cauliflower-like to coral-like, shrub-like and stalk-stock like morphology with the increasing of Cu ion concentrations towards 0.120 M, 0.155 M, 0.315 M, 0.475 M and 0.630 M Cu2+ in 0.5 M H2SO4 respectively at the same CD. Similarly, as the temperature was increased, powder morphology and apparent density were observed to be changed. The apparent density values of copper powders were found to be suitable for many of the powder metallurgy applications.

Tensile behavior of unnotched and notched tungsten--copper laminar composites

International Nuclear Information System (INIS)

Hoffman, C.A.

1976-06-01

Relations were studied between the tensile strengths of unnotched and of notched, and elastic moduli of unnotched laminar sheet or foil composites and the amounts of reinforcement. Tungsten was used as the reinforcement and copper as the matrix, and the tests were run at room temperature. Three thicknesses of tungsten (i.e., 0.00254, 0.0127, and 0.0254 cm (0.001, 0.005, and 0.010 in) were used, and the nominal volume fraction of tungsten was varied from about 0.05 to 0.95. It was found that the tensile strength of the unnotched specimens could be related to the amount of reinforcement, as could the elastic moduli, and that these values could be predicted by use of the rule of mixtures. The tensile strengths of the notched laminar composites could be predicted by use of the rule of mixtures using strengths for notched constituents, provided notch effects did not predominate. (Author)

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

High-Density Chemical Intercalation of Zero-Valent Copper into Bi 2 Se 3 Nanoribbons

KAUST Repository

Koski, Kristie J.; Cha, Judy J.; Reed, Bryan W.; Wessells, Colin D.; Kong, Desheng; Cui, Yi

2012-01-01

A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi 2Se 3 nanoribbons. Up to 60 atom % copper (Cu 7.5Bi 2Se 3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction. © 2012 American Chemical Society.

High-Density Chemical Intercalation of Zero-Valent Copper into Bi 2 Se 3 Nanoribbons

KAUST Repository

Koski, Kristie J.

2012-05-09

A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi 2Se 3 nanoribbons. Up to 60 atom % copper (Cu 7.5Bi 2Se 3) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction. © 2012 American Chemical Society.

Cyclic hot firing results of tungsten-wire-reinforced, copper-lined thrust chambers

Science.gov (United States)

Kazaroff, John M.; Jankovsky, Robert S.

1990-01-01

An advanced thrust liner material for potential long life reusable rocket engines is described. This liner material was produced with the intent of improving the reusable life of high pressure thrust chambers by strengthening the chamber in the hoop direction, thus avoiding the longitudinal cracking due to low cycle fatigue that is observed in conventional homogeneous copper chambers, but yet not reducing the high thermal conductivity that is essential when operating with high heat fluxes. The liner material produced was a tungsten wire reinforced copper composite. Incorporating this composite into two hydrogen-oxygen test rocket chambers was done so that its performance as a reusable liner material could be evaluated. Testing results showed that both chambers failed prematurely, but the crack sites were perpendicular to the normal direction of cracking indicating a degree of success in containing the tremendous thermal strain associated with high temperature rocket engines. The failures, in all cases, were associated with drilled instrumentation ports and no other damages or deformations were found elsewhere in the composite liners.

Brazing of molybdenum- and tungsten based refractory materials with copper and graphite

International Nuclear Information System (INIS)

Boutes, J.; Falbriard, P.; Rochette, P.; Nicolas, G.

1989-01-01

Molybdenum and Tungsten base refractory metals and alloys have been brazed 1. to copper between 800 0 C and 900 0 C with silver base metal; 2. to graphite, with CVD coatings between 800 0 C and 900 0 C with silver base metal and between 1100 0 C and 1200 0 C with copper base metal; 3. to graphite between 800 0 C and 1100 0 C with silver or nickel base metal. The brazed joints have been characterized by micrographic observations before and after bending tests from room temperature to 800 0 C. 2 tabs., 9 figs. (Author)

Charge-density-wave instabilities expected in monophosphate tungsten bronzes

International Nuclear Information System (INIS)

Canadell, E.; Whangbo, M.

1991-01-01

On the basis of tight-binding band calculations, we examined the electronic structures of the tungsten oxide layers found in the monophosphate tungsten bronze (MPTB) phases. The Fermi surfaces of these MPTB phases consist of five well-nested one- and two-dimensional pieces. We calculated the nesting vectors of these Fermi surfaces and discussed the expected charge-density-wave instabilities

Dissolution of copper, tin, and iron from sintered tungsten-bronze spheres in a simulated avian gizzard, and an assessment of their potential toxicity to birds

International Nuclear Information System (INIS)

Thomas, Vernon G.; McGill, Ian R.

2008-01-01

The rates of dissolution of copper, tin, and iron from sintered tungsten-bronze spheres (51.1%W, 44.4%Cu, 3.9%Sn, 0.6%Fe, by mass) were measured in an in vitro simulated avian gizzard at pH 2.0, and 42C. Most of the spheres had disintegrated completely to a fine powder by day 14. Dissolution of copper, tin, and iron from the spheres was linear over time; all r > 0.974; all P < 0.001. The mean rate of release of copper, tin, and iron was 30.4 mg, 2.74 mg, and 0.38 mg per g tungsten-bronze per day, respectively. These rates of metal release were compared to those in published studies to determine whether the simultaneous ingestion of eight spheres of 3.48 mm diameter would pose a toxic risk to birds. The potential absorption rates of iron and tin (0.54 mg Fe/day, and 3.89 mg Sn/day) from eight tungsten-bronze spheres of total mass 1.42 g would not prove toxic, based on empirical studies of tin and iron ingestion in waterfowl. The release of 43.17 mg copper/day from eight tungsten-bronze spheres, while exceeding the daily copper requirements of domesticated birds, is far below the levels of copper known to cause copper toxicosis in birds. We conclude that sintered tungsten-bronze material made into gunshot, fishing weights, or wheel balance weights, would not pose a toxic risk to wild birds when ingested

High strength tungsten heavy alloys with molybdenum additions

International Nuclear Information System (INIS)

Bose, A.; Sims, D.M.; German, R.M.

1987-01-01

Tungsten heavy alloys are candidates for numerous applications based on the unique combination of high density, high strength, and high ductility coupled with excellent machinability. Though there has been considerable research on heavy alloys, the primary focus has been on the ductility. These alloys are well suited for ballistic uses due to their high densities and it is expected that for superior ballistic performance, a high hardness, high strength and moderate ductility alloy would be ideal. The major goal of this investigation was to obtain heavy alloys with hardness greater than HRA 72. It is evident from the phase diagrams that molybdenum, which goes into solution in tungsten, nickel and iron, could act as a potential strengthening addition. With this in view, tungsten heavy alloys with molybdenum additions were fabricated from mixed elemental powders. A baseline composition of 90W-7Ni-3Fe was chosen to its good elongation and moderate strength. The molybdenum additions were made by replacing the tungsten. Compared to the baseline properties with no molybdenum addition, the strength and hardness showed a continuous increase with molybdenum addition. The ductility of the alloy continued to decrease with increasing molybdenum content, but even with 16% wt. % molybdenum of the elongation was still around 6%. An interesting facet of these alloying additions is the grain refinement that is brought about by adding to molybdenum to the system. The grain refinement is related to the lower solubility of tunbsten in the matrix due to partial displacement by molybdenum

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.

Effect on structure and mechanical property of tungsten irradiated by high intensity pulsed ion beam

Science.gov (United States)

Mei, Xianxiu; Zhang, Xiaonan; Liu, Xiaofei; Wang, Younian

2017-09-01

The anti-thermal radiation performance of tungsten was investigated by high intensity pulsed ion beam technology. The ion beam was mainly composed of Cn+ (70%) and H+ (30%) at an acceleration voltage of 250 kV under different energy densities for different number of pulses. GIXRD analysis showed that no obvious phase structural changes occurred on the tungsten, and microstress generated. SEM analysis exhibited that there was no apparent irradiation damage on the surface of tungsten at the low irradiation frequency (3 times and 10 times) and at the low energy density (0.25 J/cm2 and 0.7 J/cm2). Cracks appeared on the surface of tungsten after 100-time and 300-time irradiation. Shedding phenomenon even appeared on the surface of tungsten at the energy densities of 1.4 J/cm2 and 2.0 J/cm2. The surface nano-hardness of tungsten decreased with the increase of the pulse times and the energy density. The tungsten has good anti-thermal radiation properties under certain heat load environment.

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

Characterization of ITER tungsten qualification mock-ups exposed to high cyclic thermal loads

Energy Technology Data Exchange (ETDEWEB)

Pintsuk, Gerald, E-mail: g.pintsuk@fz-juelich.de [Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Bednarek, Maja; Gavila, Pierre [Fusion for Energy, E-08019 Barcelona (Spain); Gerzoskovitz, Stefan [Plansee SE, Innovation Services, 6600 Reutte (Austria); Linke, Jochen [Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Lorenzetto, Patrick; Riccardi, Bruno [Fusion for Energy, E-08019 Barcelona (Spain); Escourbiac, Frederic [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 Saint Paul lez Durance (France)

2015-10-15

Highlights: • Mechanical deformation of CuCrZr in case a thermal barrier layer has been formed due to impurity content in the cooling water. • Crack formation at the W/Cu interface starting at the block edge. • Porosity formation in the pure Cu interlayer. • Microstructural changes in tungsten down to the W/Cu interface, which indicates also high temperatures for the pure Cu interlayer. • Macrocrack formation in tungsten which is assumed to be ductile at the initiation point and brittle when proceeding toward the cooling tube. - Abstract: High heat flux tested small-scale tungsten monoblock mock-ups (5000 cycles at 10 MW/m{sup 2} and up to 1000 cycles at 20 MW/m{sup 2}) manufactured by Plansee and Ansaldo were characterized by metallographic means. Therein, the macrocrack formation and propagation in tungsten, its recrystallization behavior and the surface response to different heat load facilities were investigated. Furthermore, debonding at the W/Cu interface, void formation in the soft copper interlayer and microcrack formation at the inner surface of the CuCrZr cooling tube were found.

Electro-deposition metallic tungsten coatings in a Na{sub 2}WO{sub 4}-WO{sub 3} melt on copper based alloy substrate

Energy Technology Data Exchange (ETDEWEB)

Liu, Y.H., E-mail: dreamerhong77@126.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Y.C.; Liu, Q.Z.; Li, X.L.; Jiang, F. [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer The tungsten coating (>1 mm) was obtained by electro-deposition method in molten salt. Black-Right-Pointing-Pointer Different thickness tungsten coatings were obtained by using different durations. Black-Right-Pointing-Pointer Good performance of coating was obtained when pulse parameters were modulated. - Abstract: The tungsten coating was prepared by electro-deposition technique on copper alloy substrate in a Na{sub 2}WO{sub 4}-WO{sub 3} melt. The coating's surface and cross-section morphologies as well as its impurities were investigated by XPS, SEM and line analysis. Various plating durations were investigated in order to obtain an optimal coating's thickness. The results demonstrated that the electro-deposited coating was compact, voidless, crackless and free from impurities. The tungsten coating's maximum Vickers hardness was measured to be 520 HV. The tungsten coating's minimum oxygen content was determined to be 0.018 wt%. Its maximum thickness was measured to be 1043.67 {mu}m when the duration of electrolysis was set to 100 h. The result of this study has demonstrated the feasibility of having thicker tungsten coatings on copper alloy substrates. These electrodeposited tungsten coatings can be potentially implemented as reliable armour for the medium heat flux plasma facing component (PFC).

Viscosity and density models for copper electrorefining electrolytes

OpenAIRE

Kalliomäki Taina; Aji Arif T.; Aromaa Jari; Lundström Mari

2016-01-01

Viscosity and density are highly important physicochemical properties of copper electrolyte since they affect the purity of cathode copper and energy consumption [1, 2] affecting the mass and heat transfer conditions in the cell [3]. Increasing viscosity and density decreases the rate in which the anode slime falls to the bottom of the cell [4, 5] and lowers the diffusion coefficient of cupric ion (DCu2+) [6]. Decreasing the falling rate of anode slime increases movement of the slime to other...

Morphological features of the copper surface layer under sliding with high density electric current

Energy Technology Data Exchange (ETDEWEB)

Fadin, V. V., E-mail: fvv@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Aleutdinova, M. I., E-mail: aleut@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Seversk Technological Institute, Branch of State Autonomous Educational Institution of Higher Professional Education “National Research Nuclear University “MEPhI”, Seversk, 636036 (Russian Federation); Rubtsov, V. Ye., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Aleutdinova, V. A., E-mail: valery-aleut@yandex.ru [National Research St. Petersburg State Polytechnical University, St. Petersburg, 195251 (Russian Federation)

2015-10-27

Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

International Nuclear Information System (INIS)

Buzi, Luxherta; Temmerman, Greg De; Unterberg, Bernhard; Reinhart, Michael; Litnovsky, Andrey; Philipps, Volker; Oost, Guido Van; Möller, Sören

2014-01-01

Systematic study of deuterium irradiation effects on tungsten was done under ITER – relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER – like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux densities (high: 3.5–7 · 10 23 D + /m 2 s and low: 9 · 10 21 D + /m 2 s). Particle fluence and ion energy, respectively 10 26 D + /m 2 and ∼38 eV were kept constant in all cases. The experiments were performed at three different surface temperatures 530 K, 630 K and 870 K. Experimental results concerning the deuterium retention and surface modifications of low flux exposure confirmed previous investigations. At temperatures 530 K and 630 K, deuterium retention was higher at lower flux density due to the longer exposure time (steady state plasma operation) and a consequently deeper diffusion range. At 870 K, deuterium retention was found to be higher at high flux density according to the thermal desorption spectroscopy (TDS) measurements. While blisters were completely absent at low flux density, small blisters of about 40–50 nm were formed at high flux density exposure. At the given conditions, a relation between deuterium retention and blister formation has been found which has to be considered in addition to deuterium trapping in defects populated by diffusion

Optimization of sedimentation of tungsten on copper substrate for production of {sup 186g}Re via {sup 186}W(p,n) nuclear reaction: Feasibility of using high current, long irradiation

Energy Technology Data Exchange (ETDEWEB)

Kakavand, T., E-mail: Tayeb@znu.ac.ir [Department of Physics, Faculty of Science, Imam Khomeini International University, Qazvin (Iran, Islamic Republic of); Mirzaii, M.; Khaleghi, M. [Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute, AEOI, Karaj (Iran, Islamic Republic of); Eslami, M. [Department of Physics, Faculty of Science, University of Zanjan, Zanjan (Iran, Islamic Republic of)

2016-01-01

Highlights: • Optimization of tungsten sedimentation for bulk production of {sup 186}Re. • Influence of targetry parameters on stress-bearing of the target during proton irradiation. • Activity measurement for {sup 186}Re produced via {sup nat}W(p,xn) reaction. - Abstract: Tungsten is recognized as one of the important metals used in cyclotron targets for production of several vital radioisotopes. Adequate adhesion of the prepared targets to its substrate is a significant parameter that makes them optimized for high current beam collisions. The target morphology should be paid special attention as another important parameter. In this work, a rather thick layer of tungsten is deposited on a copper substrate by sedimentation technique to produce {sup 186g}Re radionuclide via {sup 186}W(p,n) reaction. Consecutive sedimentation experiments are carried out to determine the best suspension solution. The prepared targets are evaluated in morphology by scanning electron microscope. A mixture of 1 g tungsten powder, 250 mg ethyl cellulose and 5 mL acetone is concluded for desirable target adhesion. Irradiation of the targets by 20 μA proton current (15 MeV energy) for 5 h shows that they can withstand the proton beam.

Effect of pulse current parameters on microstructure of tungsten coating electroplated from Na{sub 2}WO{sub 4}–WO{sub 3}–NaPO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fan; Zhang, Yingchun, E-mail: zycustb@163.com; Sun, Ningbo; Len, Jiaxun

2015-03-15

Highlights: • Tungsten coatings were electroplated on cooper alloy by pulse plating. • Increasing current density resulted in an increase in grain size of tungsten coating. • With the increase in duty cycle, the grain size of tungsten coating increased. • The pulse period had an insignificant effect on the tungsten grain size. - Abstract: The tungsten coatings with low oxygen content were prepared on copper alloy substrate by pulse electroplating in Na{sub 2}WO{sub 4}–WO{sub 3}–NaPO{sub 3} molten salt. A series of tungsten coatings with compact morphologies were successfully obtained under various conditions. The influences of current density, duty cycle and period on tungsten grain size and coatings thickness were investigated. The results demonstrated that current density was the most important factor influencing tungsten grain size, which had a positive correlation with current density. The thickness of coating decreased when the current density was up to 80 mA cm{sup −2}. However, the tungsten grain size, tungsten coating thickness and current efficiency changed a little with the increase in pulse periods.

Mechanical alloying and sintering of nanostructured tungsten carbide-reinforced copper composite and its characterization

International Nuclear Information System (INIS)

Yusoff, Mahani; Othman, Radzali; Hussain, Zuhailawati

2011-01-01

Research highlights: → W 2 C phase was formed at short milling time while WC only appears after longer milling time. → Cu crystallite size decreased but internal strain increased with increasing milling time. → Increasing milling time induced more WC formation, thus improving the hardness of the composite. → Electrical conductivity is reduced due to powder refinement and the presence of carbide phases. -- Abstract: Elemental powders of copper (Cu), tungsten (W) and graphite (C) were mechanically alloyed in a planetary ball mill with different milling durations (0-60 h), compacted and sintered in order to precipitate hard tungsten carbide particles into a copper matrix. Both powder and sintered composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and assessed for hardness and electrical conductivity to investigate the effects of milling time on formation of nanostructured Cu-WC composite and its properties. No carbide peak was detected in the powder mixtures after milling. Carbide WC and W 2 C phases were precipitated only in the sintered composite. The formation of WC began with longer milling times, after W 2 C formation. Prolonged milling time decreased the crystallite size as well as the internal strain of Cu. Hardness of the composite was enhanced but electrical conductivity reduced with increasing milling time.

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 particle flux density and temperature on surface modifications of tungsten and deuterium retention

Energy Technology Data Exchange (ETDEWEB)

Buzi, Luxherta, E-mail: l.buzi@fz-juelich.de [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Université de Lorraine, Institut Jean Lamour, CNRS UMR 7198, Bvd. des Aiguillettes, F-54506 Vandoeuvre (France); Temmerman, Greg De [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Edisonbaan 14, 3439 MN, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Unterberg, Bernhard; Reinhart, Michael; Litnovsky, Andrey; Philipps, Volker [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Oost, Guido Van [Ghent University, Department of Applied Physics, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Möller, Sören [Institut für Energie und Klimaforschung – Plasmaphysik, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany)

2014-12-15

Systematic study of deuterium irradiation effects on tungsten was done under ITER – relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER – like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux densities (high: 3.5–7 · 10{sup 23} D{sup +}/m{sup 2} s and low: 9 · 10{sup 21} D{sup +}/m{sup 2} s). Particle fluence and ion energy, respectively 10{sup 26} D{sup +}/m{sup 2} and ∼38 eV were kept constant in all cases. The experiments were performed at three different surface temperatures 530 K, 630 K and 870 K. Experimental results concerning the deuterium retention and surface modifications of low flux exposure confirmed previous investigations. At temperatures 530 K and 630 K, deuterium retention was higher at lower flux density due to the longer exposure time (steady state plasma operation) and a consequently deeper diffusion range. At 870 K, deuterium retention was found to be higher at high flux density according to the thermal desorption spectroscopy (TDS) measurements. While blisters were completely absent at low flux density, small blisters of about 40–50 nm were formed at high flux density exposure. At the given conditions, a relation between deuterium retention and blister formation has been found which has to be considered in addition to deuterium trapping in defects populated by diffusion.

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

Method of making a long life high current density cathode from tungsten and iridium powders using a quaternary compound as the impregnant

International Nuclear Information System (INIS)

Branovich, L.E.; Smith, B.; Freemen, G.L.; Eckart, D.W.

1990-01-01

This patent describes a method of making a long life high current density cathode. It is suitable for operation in microwave devices. It is made from tungsten and iridium powders using a quaternary compound including barium, oxygen, a metal selected from the group consisting of osmium, iridium, rhodium, and rhenium, and a metal selected from the group consisting of strontium, calcium, scandium, and titanium as the impregnant

Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

Science.gov (United States)

Constantin, M. A.; Boșneag, A.; Nitu, E.; Iordache, M.

2017-10-01

Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

Development of bonding techniques between tungsten and copper alloy for plasma facing components by HIP method. 1. Bonding between tungsten and oxygen free copper

International Nuclear Information System (INIS)

Saito, Shigeru; Fukaya, Kiyoshi; Ishiyama, Shintaro; Eto, Motokuni; Akiba, Masato

1999-08-01

In recent years, it has been considered that W (tungsten) is one of candidate materials for armor tiles of plasma facing components, like first wall or divertor, of fusion reactor. On the other hand, oxygen free high thermal conductivity (OFHC)-copper is proposed as heat sink materials behind the plasma facing materials because of its high thermal conductivity. However, plasma facing components are exposed to cyclic high heat load and heavily irradiated by 14 MeV neutron. Under these conditions, many unfavorable effects, for instance, thermal stresses of bonding interface, irradiation damage and He atom production by nuclear transmutation, will be decreased bonding strength between W and Cu alloys. Therefore, it is necessary to develop a reliable bonding techniques in order to make plasma facing components which can resist them. Then, we started the bonding technology development by hot isostatic press (HIP) method to bond W with Cu alloys. In this experiments, to optimize HIP bonding conditions, four point bending were performed for each bonded conditions at temperature from R.T. to 873 K and we could get the best HIP bonding conditions for W and OFHC-Cu as 1273 K x 2 hours x 147 MPa. To evaluate bonding strength of the specimen bonded at these conditions, tensile tests were also performed at same temperature range. The tensile strength was similar with OFHC-Cu which were treated at same conditions. (author)

The effect of particle structure on apparent density of electrolytic copper powder

Directory of Open Access Journals (Sweden)

K. I. POPOV

2001-12-01

Full Text Available The quantitative microstructural analysis and the sieve analysis of copper powder as well as the scanning electron microscopy analysis of the copper powders particles were performed. It was found that the structure of the copper powder particles determines the apparent density of copper powder. The powder particles from the same fractions of different powders occupy approximately the same volume, but the structure of metallic copper is very different. This causes the difference in apparent densities of copper powder obtained under different conditions. The more dendritic is the structure of powder particles the smaller is the apparent density of copper powder.

Cyclic saturation behavior of tungsten monofilament-reinforced monocrystalline copper matrix composites

International Nuclear Information System (INIS)

Zhang, J.; Laird, C.

1999-01-01

Studies on saturation behavior produced by cyclic deformation have been conducted on tungsten monofilament-reinforced monocrystalline copper composites. The effect of the fiber on strain localization has been investigated using interferometry. For a given applied strain amplitude, local strain and volume fraction of the persistent slip bands (PSBs) in the composite appeared no different from those observed in monolithic copper single crystals. However, the distribution of the PSBs was observed to be more uniform, and the total number of PSBs is substantially higher than that in monolithic crystals. The PSBs appeared mostly in the form of micro-PSBs or macro-PSBs with very limited width. Instead of expanding existing PSBs, new PSBs were more likely to nucleate at new locations during cyclic deformation. The volume fraction and width of the PSBs were observed to increase during saturation, which indicates that some of the PSBs become aged and new PSBs form in order to continue to carry the plastic strain. A rule of mixtures model was established to link the cyclic stress-strain response of the monocrystalline composites to the behavior of monolithic single crystals and fibers. The results calculated from the model show very good agreement with the experimental data

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)

Dense Pure Tungsten Fabricated by Selective Laser Melting

Directory of Open Access Journals (Sweden)

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.

Effect of composition on the high rate dynamic behaviour of tungsten heavy alloys

Directory of Open Access Journals (Sweden)

Latif Kesemen

2015-01-01

Full Text Available Tungsten heavy alloys are currently used as kinetic energy penetrators in military applications due to their high density and superior mechanical properties. In the literature, quasi-static properties of different tungsten heavy alloys based on W-Ni-Cu and W-Ni-Fe ternary systems are well documented and presented. However, comparison of the dynamic behaviour of these alloys in terms of the correlation between quasi-static mechanical characterization and dynamical properties is lacking. In the present study, dynamic properties of tungsten heavy alloys having different binder phase compositions (90W-7Ni-3Cu and 90W-8Ni-2Fe at different projectile velocities were investigated. The examined and tested alloys were produced through the conventional powder metallurgy route of mixing, cold compaction and sintering. Mechanical characterization of these alloys was performed. In the ballistic tests, cylindrical tungsten heavy alloys with L/D ratio of 3 were impacted to hardened steel target at different projectile velocities. After the ballistic tests, deformation characteristics of test specimens during dynamic loading were evaluated by comparing the change of length and diameter of the specimens versus kinetic energy densities. The study concluded that 90W-8Ni-2Fe alloy has better perforation characteristics than 90W-7Ni-3Cu alloy.

Effect of cathodic current density on performance of tungsten coatings on molybdenum prepared by electrodeposition in molten salt

Science.gov (United States)

Jiang, Fan

2016-02-01

Smooth tungsten coatings were prepared at current density below 70 mA cm-2 by electrodeposition on molybdenum substrate from Na2WO4-WO3 -melt at 1173 K in air atmosphere. As the current density reached up to 90 mA cm-2, many significant nodules were observed on the surface of the coating. Surface characterization, microstructure and mechanical properties were performed on the tungsten coatings. As the increasing of current density, the preferred orientation of the coatings changed to (2 0 0). All coatings exhibited columnar-grained-crystalline. There was about a 2 μm thick diffusion layer between tungsten coating and molybdenum substrate. The bending test revealed the tungsten coating had -good bonding strength with the molybdenum substrate. There is a down trend of the grain size of the coating on molybdenum as the current density increased from 30 mA cm-2 to 50 mA cm-2. The coating obtained at 50 mA cm-2 had a minimum grain size of 4.57 μm, while the microhardness of this coating reached to a maximum value of 495 HV.

High heat flux testing of TiC coated molybdenum with a tungsten intermediate layer

International Nuclear Information System (INIS)

Fujitsuka, Masakazu; Fukutomi, Masao; Okada, Masatoshi

1988-01-01

The use of low atomic number (Z) material coatings for fusion reactor first-wall components has proved to be a valuable technique to reduce the plasma radiation losses. Molybdenum coated with titanium carbide is considered very promising since it has a good capability of receiving heat from the plasma. An interfacial reaction between the TiC film and the molybdenum substrate, however, causes a severe deterioration of the film at elevated temperatures. In order to solve this problem a TiC coated molybdenum with an intermediate tungsten layer was developed. High temperature properties of this material was evaluated by a newly devised electron beam heating apparatus. TiC coatings prepared on a vacuum-heat-treated molybdenum with a tungsten intermediate layer showed good high temperature stability and survived 2.0 s pulses of heating at a power density as high as 53 MW/m 2 . The melt area of the TiC coatings in high heat flux testings also markedly decreased when a tungsten intermediate layer was applied. The melting mechanism of the TiC coatings with and without a tungsten intermediate layer was discussed by EPMA measurements. (author)

Micro-powder injection moulding of tungsten

International Nuclear Information System (INIS)

Zeep, B.

2007-12-01

high hardness comparable to recrystalized material as well as a tensile strength of 290 N/mm 2 and an elongation of break at 35 %. Nevertheless, by conventional sintering extensive grain growth up to 68 μm was observed for samples with a sintered density of 99% theoretical density. To avoid extensive grain growth a HIP-process was developed for injection moulded tungsten samples, achieving a grain size of 5,5 μm. In addition to tungsten, a wide range of tungsten alloys are of industrial interest for e.g. electrodes, thermal shielding, microelectronics and automotive applications. Accordingly the process developments for micro injection moulding has successfully been extended to oxide disperse strengthened tungsten and tungsten heavy alloys. (orig.)

Micro-engineered first wall tungsten armor for high average power laser fusion energy systems

Science.gov (United States)

Sharafat, Shahram; Ghoniem, Nasr M.; Anderson, Michael; Williams, Brian; Blanchard, Jake; Snead, Lance; HAPL Team

2005-12-01

The high average power laser program is developing an inertial fusion energy demonstration power reactor with a solid first wall chamber. The first wall (FW) will be subject to high energy density radiation and high doses of high energy helium implantation. Tungsten has been identified as the candidate material for a FW armor. The fundamental concern is long term thermo-mechanical survivability of the armor against the effects of high temperature pulsed operation and exfoliation due to the retention of implanted helium. Even if a solid tungsten armor coating would survive the high temperature cyclic operation with minimal failure, the high helium implantation and retention would result in unacceptable material loss rates. Micro-engineered materials, such as castellated structures, plasma sprayed nano-porous coatings and refractory foams are suggested as a first wall armor material to address these fundamental concerns. A micro-engineered FW armor would have to be designed with specific geometric features that tolerate high cyclic heating loads and recycle most of the implanted helium without any significant failure. Micro-engineered materials are briefly reviewed. In particular, plasma-sprayed nano-porous tungsten and tungsten foams are assessed for their potential to accommodate inertial fusion specific loads. Tests show that nano-porous plasma spray coatings can be manufactured with high permeability to helium gas, while retaining relatively high thermal conductivities. Tungsten foams where shown to be able to overcome thermo-mechanical loads by cell rotation and deformation. Helium implantation tests have shown, that pulsed implantation and heating releases significant levels of implanted helium. Helium implantation and release from tungsten was modeled using an expanded kinetic rate theory, to include the effects of pulsed implantations and thermal cycles. Although, significant challenges remain micro-engineered materials are shown to constitute potential

Micro-engineered first wall tungsten armor for high average power laser fusion energy systems

International Nuclear Information System (INIS)

Sharafat, Shahram; Ghoniem, Nasr M.; Anderson, Michael; Williams, Brian; Blanchard, Jake; Snead, Lance

2005-01-01

The high average power laser program is developing an inertial fusion energy demonstration power reactor with a solid first wall chamber. The first wall (FW) will be subject to high energy density radiation and high doses of high energy helium implantation. Tungsten has been identified as the candidate material for a FW armor. The fundamental concern is long term thermo-mechanical survivability of the armor against the effects of high temperature pulsed operation and exfoliation due to the retention of implanted helium. Even if a solid tungsten armor coating would survive the high temperature cyclic operation with minimal failure, the high helium implantation and retention would result in unacceptable material loss rates. Micro-engineered materials, such as castellated structures, plasma sprayed nano-porous coatings and refractory foams are suggested as a first wall armor material to address these fundamental concerns. A micro-engineered FW armor would have to be designed with specific geometric features that tolerate high cyclic heating loads and recycle most of the implanted helium without any significant failure. Micro-engineered materials are briefly reviewed. In particular, plasma-sprayed nano-porous tungsten and tungsten foams are assessed for their potential to accommodate inertial fusion specific loads. Tests show that nano-porous plasma spray coatings can be manufactured with high permeability to helium gas, while retaining relatively high thermal conductivities. Tungsten foams where shown to be able to overcome thermo-mechanical loads by cell rotation and deformation. Helium implantation tests have shown, that pulsed implantation and heating releases significant levels of implanted helium. Helium implantation and release from tungsten was modeled using an expanded kinetic rate theory, to include the effects of pulsed implantations and thermal cycles. Although, significant challenges remain micro-engineered materials are shown to constitute potential

Molecular dynamics and density functional simulations of tungsten nanostructure formation by helium plasma irradiation

International Nuclear Information System (INIS)

Ito, A.M.; Takayama, A.; Oda, Y.

2014-10-01

For the purposes of long-term use of tungsten diverter walls, it is necessary to suppress the surface deterioration due to the helium ash which induces the formations of helium bubbles and tungsten fuzzy nanostructures. In the present paper, the formation mechanisms of helium bubbles and tungsten fuzzy nanostructures were explained by the four-step process which is composed of the penetration process, the diffusion and agglomeration process, the helium bubble growth process and the tungsten fuzzy nanostructure formation process. The first to third step processes of the four-step process were investigated by using binary collision approximation, density functional theory and molecular dynamics, respectively. Furthermore, newly developed molecular dynamics and Monte-Carlo hybrid simulation has successfully reproduced the early formation process of tungsten fuzzy nanostructure. From these simulations, we here suggest the following key mechanisms of the formations of helium bubbles and tungsten fuzzy nanostructures: (1) By comparison between helium, neon, argon and hydrogen, the noble gas atoms can agglomerate limitlessly not only at a vacancy but also at an interstitial site. In particular, at the low incident energy, only helium atoms bring about the nucleation for helium bubble. (2) In the helium bubble growth process, the strain of the tungsten material around a helium atom is released as a dislocation loop, which is regarded as the loop punching phenomenon. (3) In the tungsten nanostructure formation process, the bursting of a helium bubble forms cavity and convexity in the surface. The helium bubbles tend to be grown and to burst at the cavity region, and then the difference of height between the cavity and convexity on the surface are enhanced. Consequently, the tungsten fuzzy nanostructure is formed. (author)

Effect of cathodic current density on performance of tungsten coatings on molybdenum prepared by electrodeposition in molten salt

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fan, E-mail: jiangfan1109@163.com [Department of Materials and Physics, School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Nanjing 210044, Jiangsu Province (China); School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 10083 (China)

2016-02-15

Graphical abstract: - Highlights: • Tungsten coatings were successfully electroplated on molybdenum substrate. • The electrodeposition was studied in the air atmosphere at 1173 K. • The coating had columnar structure with preferential growth orientation of (2 0 0). • The coating obtained at 50 mA cm{sup −2} had a maximum microhardness of 495 HV. - Abstract: Smooth tungsten coatings were prepared at current density below 70 mA cm{sup −2} by electrodeposition on molybdenum substrate from Na{sub 2}WO{sub 4}-WO{sub 3} -melt at 1173 K in air atmosphere. As the current density reached up to 90 mA cm{sup −2}, many significant nodules were observed on the surface of the coating. Surface characterization, microstructure and mechanical properties were performed on the tungsten coatings. As the increasing of current density, the preferred orientation of the coatings changed to (2 0 0). All coatings exhibited columnar-grained-crystalline. There was about a 2 μm thick diffusion layer between tungsten coating and molybdenum substrate. The bending test revealed the tungsten coating had –good bonding strength with the molybdenum substrate. There is a down trend of the grain size of the coating on molybdenum as the current density increased from 30 mA cm{sup −2} to 50 mA cm{sup −2}. The coating obtained at 50 mA cm{sup −2} had a minimum grain size of 4.57 μm, while the microhardness of this coating reached to a maximum value of 495 HV.

Fracture mechanical analysis of tungsten armor failure of a water-cooled divertor target

Energy Technology Data Exchange (ETDEWEB)

Li, Muyuan; Werner, Ewald [Lehrstuhl für Werkstoffkunde und Werkstoffmechanik, Technische Universität München, Boltzmannstr. 15, 85748 Garching (Germany); You, Jeong-Ha, E-mail: you@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

2014-11-15

Highlights: • The FEM-based VCE method and XFEM were employed for computing K{sub I} (or J-integral) and predicting progressive cracking, respectively. • The most probable pattern of crack formation is radial cracking in the tungsten armor block. • The most probable site of cracking is the upper interfacial region of the tungsten armor block adjacent to the top position of the copper interlayer. • The initiation of a major crack becomes likely, only when the strength of tungsten armor block is significantly reduced from its original strength. - Abstract: The inherent brittleness of tungsten at low temperature and the embrittlement by neutron irradiation are its most critical weaknesses for fusion applications. In the current design of the ITER and DEMO divertor, the high heat flux loads during the operation impose a strong constraint on the structure–mechanical performance of the divertor. Thus, the combination of brittleness and the thermally induced stress fields due to the high heat flux loads raises a serious reliability issue in terms of the structural integrity of tungsten armor. In this study, quantitative estimates of the vulnerability of the tungsten monoblock armor cracking under stationary high heat flux loads are presented. A comparative fracture mechanical investigation has been carried out by means of two different types of computational approaches, namely, the extended finite element method (XFEM) and the finite element method (FEM)-based virtual crack tip extension (VCE) method. The fracture analysis indicates that the most probable pattern of crack formation is radial cracking in the tungsten armor starting from the interface to tube and the most probable site of cracking is the upper interfacial region of the tungsten armor adjacent to the top position of the copper interlayer. The strength threshold for crack initiation and the high heat flux load threshold for crack propagation are evaluated based on XFEM simulations and computations

Paradoxical effects of density on measurement of copper tolerance in Silene paradoxa L.

Science.gov (United States)

Capuana, Maurizio; Colzi, Ilaria; Buccianti, Antonella; Coppi, Andrea; Palm, Emily; Del Bubba, Massimo; Gonnelli, Cristina

2018-01-01

This work investigated if the assessment of tolerance to trace metals can depend on plant density in the experimental design. A non-metallicolous and a metallicolous populations of Silene paradoxa were hydroponically cultivated at increasing density and in both the absence (-Cu conditions) and excess of copper (+Cu conditions). In -Cu conditions, the metallicolous population showed a lower susceptibility to plant density in comparison to the non-metallicolous one, explained by a higher capacity of the metallicolous population to exploit resources. In +Cu conditions, an alleviating effect of increasing density was found in roots. Such effect was present to a greater extent in the non-metallicolous population, thus making the populations equally copper-tolerant at the highest density used. In shoots, an additive effect of increasing plant density to copper toxicity was reported. Its higher intensity in the metallicolous population reverted the copper tolerance relationship at the highest plant densities used. In both populations, a density-induced decrease in root copper accumulation was observed, thus concurring to the reported mitigation in +Cu conditions. Our work revealed the importance of density studies on the optimization of eco-toxicological bioassays and of metal tolerance assessment and it can be considered the first example of an alleviating effect of increasing plant number on copper stress in a metallophyte.

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 fibre-reinforced composites for advanced plasma facing components

OpenAIRE

Neu, R.; Riesch, J.; Müller, A.v.; Balden, M.; Coenen, J.W.; Gietl, H.; Höschen, T.; Li, M.; Wurster, S.; You, J.-H.

2016-01-01

The European Fusion Roadmap foresees water cooled plasma facing components in a first DEMO design in order to provide enough margin for the cooling capacity and to only moderately extrapolate the technology which was developed and tested for ITER. In order to make best use of the water cooling concept copper (Cu) and copper-chromium-zirconium alloy (CuCrZr) are envisaged as heat sink whereas as armour tungsten (W) based materials will be used. Combining both materials in a high heat flux comp...

Sub-surface microstructure of single and polycrystalline tungsten after high flux plasma exposure studied by TEM

Energy Technology Data Exchange (ETDEWEB)

Dubinko, A., E-mail: adubinko@sckcen.be [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Terentyev, D. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Bakaeva, A. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Hernández-Mayoral, M. [Division of Materials, CIEMAT, 28040 Madrid (Spain); De Temmerman, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul-lez-Durance Cedex (France); Buzi, L. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany); Noterdaeme, J.-M. [Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Unterberg, B. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany)

2017-01-30

Highlights: • Plasma exposure induces dislocation-dominated microstructure as indicated by TEM. • Plasma exposure increases surface dislocation density by an order of magnitude in the polycrystalline tungsten. • Intensive dislocation-grain boundary interaction observed in polycrystalline tungsten. • Dislocation loops are observed in both polycrystalline and single crystal tungsten. - Abstract: We have performed high flux plasma exposure of tungsten and subsequent microstructural characterization using transmission electron microscopy (TEM) techniques. The aim was to reveal the nanometric features in the sub-surface region as well as to compare the microstructural evolution in tungsten single crystal and ITER-relevant specification. In both types of samples, TEM examination revealed the formation of a dense dislocation network and dislocation tangles. The estimated dislocation density in the sub-surface region was of the order of 10{sup 14} m{sup −2} and it gradually decreased with a depth position of the examined sample. Besides individual dislocation lines, networks and tangles, the interstitial dislocation loops have been observed in all examined samples only after the exposure. Contrary to that, examination of the pristine single crystal W and backside of the plasma-exposed samples did not reveal the presence of dislocation loops and tangles. This clearly proves that high flux plasma exposure induces severe plastic deformation in the sub-surface region irrespective of the presence of initial dislocations and sub-grains, and the formation of dislocation tangles, networks and interstitial loops is a co-product of thermal stress and intensive plasma particles uptake.

Tungsten fibre-reinforced composites for advanced plasma facing components

Directory of Open Access Journals (Sweden)

R. Neu

2017-08-01

Full Text Available The European Fusion Roadmap foresees water cooled plasma facing components in a first DEMO design in order to provide enough margin for the cooling capacity and to only moderately extrapolate the technology which was developed and tested for ITER. In order to make best use of the water cooling concept copper (Cu and copper-chromium-zirconium alloy (CuCrZr are envisaged as heat sink whereas as armour tungsten (W based materials will be used. Combining both materials in a high heat flux component asks for an increase of their operational range towards higher temperature in case of Cu/CuCrZr and lower temperatures for W. A remedy for both issues- brittleness of W and degrading strength of CuCrZr- could be the use of W fibres (Wf in W and Cu based composites. Fibre preforms could be manufactured with industrially viable textile techniques. Flat textiles with a combination of 150/70 µm W wires have been chosen for layered deposition of tungsten-fibre reinforced tungsten (Wf/W samples and tubular multi-layered braidings with W wire thickness of 50 µm were produced as a preform for tungsten-fibre reinforced copper (Wf /Cu tubes. Cu melt infiltration was performed together with an industrial partner resulting in sample tubes without any blowholes. Property estimation by mean field homogenisation predicts strongly enhanced strength of the Wf/CuCrZr composite compared to its pure CuCrZr counterpart. Wf /W composites show very high toughness and damage tolerance even at room temperature. Cyclic load tests reveal that the extrinsic toughening mechanisms counteracting the crack growth are active and stable. FEM simulations of the Wf/W composite suggest that the influence of fibre debonding, which is an integral part of the toughening mechanisms, and reduced thermal conductivity of the fibre due to the necessary interlayers do not strongly influence the thermal properties of future components.

High-resolution angle-resolved photoemission investigation of potassium and phosphate tungsten bronzes

International Nuclear Information System (INIS)

Paul, Sanhita; Kumari, Spriha; Raj, Satyabrata

2016-01-01

Highlights: • Electronic structure of potassium and phosphate tungsten bronzes. • Origin of transport anomalies in bronzes. • Flat segments of Fermi surfaces are connected by a nesting vector, q. • Nesting driven charge-density wave is responsible for the anomalies. - Abstract: We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional ab initio theoretical calculation to study the electronic structure of potassium (K_0_._2_5WO_3) and phosphate (P_4W_1_2O_4_4) tungsten bronzes. We have experimentally determined the band dispersions and Fermi surface topology of these bronzes and compared with our theoretical calculations and a fair agreement has been seen between them. Our experimental as well as theoretical investigation elucidates the origin of transport anomalies in these bronzes. The Fermi surfaces of these bronzes consist of flat patches, which can be connected with each other by a constant nesting wave vector, q. The scattering wave vectors found from diffraction measurements match with these nesting vectors and the anomalies in the transport properties of these bronzes can be well explained by the evolution of charge-density wave with a partial nesting between the flat segments of the Fermi surfaces.

Copper infiltrated high speed steels based composites

International Nuclear Information System (INIS)

Madej, M.; Lezanski, J.

2003-01-01

High hardness, mechanical strength, heat resistance and wear resistance of M3/2 high speed steel (HSS) make it an attractive material. Since technological and economical considerations are equally important, infiltration of high-speed steel skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. Attempts have been made to describe the influence of the production process parameters and alloying additives, such as tungsten carbide on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2+10% Wc, M3/2=30% WC. The powders were uniaxially cold compacted in a cylindrical die at 800 MPa. The green compacts were sintered in vacuum at 1150 o C for 60 minutes. Thereby obtained porous skeletons were subsequently infiltrated with cooper, by gravity method, in vacuum furnace at 1150 o C for 15 minutes. (author)

Developments toward the use of tungsten as armour material in plasma facing components promoted by Euratom-CEA Association

International Nuclear Information System (INIS)

Mitteau, R.; Missiaen, J.M.; Brustolin, P.

2006-01-01

Tungsten is increasingly considered as a prime candidate armour material facing the plasma in fusion experiments (ASDEX, JET, ITER). This material is, however, a challenge for the engineers due to its brittleness at room temperature. Its bonding to structural or cooled substrates is a critical issue. The Euratom-CEA Association promotes the development of evolutionary techniques aiming to produce high performance assemblies between tungsten and various substrates. These are 1) functionally graded tungsten to copper, 2) direct electron beam welding of tungsten to Mo-alloy TZM and 3) the characterisation of tungsten coatings deposited on carbon fibre composite by high energy deposition processes. 1) A functionally graded material eliminates the singular point which weakens the heterogeneous assembly, reducing the stresses and allowing a better behaviour. The sintering of submicronic W-Cu powders is investigated. The green shape is processed from W-CuO powder, which is reduced by a hydrogen flow. The compaction and sintering of layers of various compositions (10 to 30 % Cu) produces an assembly (density of ∼ 94%) with a good cohesion. However, the gradient is not effectively controlled, because of the migration of melt copper during the sintering. Future work aims to improve the process by using spark or microwave assisted sintering. 2) Electron beam welding of Mo-alloy TZM is investigated, to produce high temperature components required by radiation cooled PFCs. They require only mechanical properties and no vacuum sealing. The driving line is to use simple tungsten shapes to reduce the milling cost. In spite of low weldable properties of the refractory alloys, a good bonding up to a depth of 5 mm is obtained. Hardness measurements show that the melt area and the heat affected zone are harder than TZM, the weakest materials at 230 Hv. Quench tests in water from up to 2000 o C are done without apparent crack formation. 3) Finally, characterisation techniques are

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.

The Microstructure and Properties of Super Martensitic Stainless Steel Microalloyed with Tungsten and Copper

Science.gov (United States)

Ye, Dong; Li, Jun; Liu, Yu-Rong; Yong, Qi-Long; Su, Jie; Cao, Jian-Chun; Tao, Jing-Mei; Zhao, Kun-Yu

2011-06-01

The microstructure and properties of super martensitic stainless steel (SMSS) microalloyed with tungsten and copper were studied by means of optical microscopy, dilatometer, X-ray diffraction, and tensile tests. The results showed that the microstructure of SMSS, after quenching and tempering, was a typical biphase structure with tempered martensite and reversed austenite dispersedly distributed in the martensite matrix. W and Cu were added into the SMSS to reduce the transformation temperature (Ms) and improve the strength and hardness of the matrix by grain refining and solid solution strengthening. Thermocalc calculations confirmed that M23C6 compound and Laves phase were precipitated during tempering in the investigated steel. Compared with the traditional SMSS, the steel microalloyed with W and Cu performed better mechanical properties.

Effect of coating current density on the wettability of electrodeposited copper thin film on aluminum substrate

Directory of Open Access Journals (Sweden)

Arun Augustin

2016-09-01

Full Text Available Copper is the only one solid metal registered by the US Environmental Protection Agency as an antimicrobial touch surface. In touch surface applications, wettability of the surface has high significance. The killing rate of the harmful microbes depends on the wetting of pathogenic solution. Compared to the bulk copper, coated one on aluminum has the advantage of economic competitiveness and the possibility of manufacturing complex shapes. In the present work, the copper coating on the aluminum surface has successfully carried out by electrodeposition using non cyanide alkaline bath. To ensure good adhesion strength, the substrate has been pre-zincated prior to copper deposition. The coating current density is one of the important parameters which determine the nucleation density of the copper on the substrate. To understand the effect of current density on wettability, the coating has done at different current densities in the range of 3 A dm−2 to 9 A dm−2 for fixed time interval. The grain size has been measured from TEM micrographs and showed that as current density increases, grain size reduces from 62 nm to 35 nm. Since the grain size reduces, grain boundary volume has increases. As a result the value of strain energy (calculated by Williamson–Hall method has increased. The density of nodular morphology observed in SEM analysis has been increased with coating current density. Further, wettability studies with respect to double distilled water on the electrodeposited copper coatings which are coated at different current densities are carried out. At higher current density the coating is more wettable by water because at these conditions grain size of the coating decreases and morphology of grain changes to a favorable dense nodularity.

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

On the origin, properties, and implications of asymmetries in the tungsten impurity density in tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Odstrcil, Tomas

2017-07-03

In this thesis, the transport of tungsten ions is studied in the plasma of ASDEX Upgrade tokamak. The plasma facing components of the fusion reactors are expected to be built from high-Z materials such as W, Mo or Fe. These materials provide advantages like a high melting point, small erosion rates, and low tritium retention. However, due to the interaction of the plasma with the wall, ions of this material will be inevitably present also in the main plasma. These ions are not entirely stripped even at fusion plasma temperatures, and therefore emit strong line radiation, which can significantly degrade the performance of the fusion plasma. Thus the understanding and control of impurity transport are of critical importance to the success of fusion. The high mass and charge of the heavy impurities make them susceptible to some of the forces acting upon the plasma, resulting in a poloidal variation of their density. The most prominent are the centrifugal force arising from the plasma rotation and the electric force caused by magnetically trapped non-thermal ions. Furthermore, the poloidal asymmetries should have a significant impact on the radial transport of heavy ions, which was widely ignored up to date. In the present work, the poloidal asymmetries in the heavy impurity density were inferred from the soft X-ray radiation using a newly developed tomographic method. The high accuracy of the tomography and of the model for the centrifugal force allowed to identify for the first time in an experiment the effect of the fast ion distribution produced by neutral beam injection on the poloidal asymmetry of the tungsten density. The measured asymmetry was compared to several fast ion models, and the best match was found with the Monte Carlo code in the TRANSP code suite that includes finite orbits effects of the fast ions. Similarly, fast ions accelerated by ion cyclotron heating and localized mainly in the outboard side of the plasma due to a magnetic trapping and produce

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%

Tungsten impurity transport experiments in Alcator C-Mod to address high priority research and development for ITER

Energy Technology Data Exchange (ETDEWEB)

Loarte, A.; Polevoi, A. R.; Hosokawa, M. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Reinke, M. L. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Chilenski, M.; Howard, N.; Hubbard, A.; Hughes, J. W.; Rice, J. E.; Walk, J. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Köchl, F. [Technische Universität Wien, Atominstitut, Stadionallee 2, 1020 Vienna (Austria); Pütterich, T.; Dux, R. [Max-Planck-Institut für Plasmaphysik, Boltzmanstraße 2, D-85748 Garching (Germany); Zhogolev, V. E. [NRC “Kurchatov Institute,” Kurchatov Square 1, 123098 Moscow (Russian Federation)

2015-05-15

Experiments in Alcator C-Mod tokamak plasmas in the Enhanced D-alpha H-mode regime with ITER-like mid-radius plasma density peaking and Ion Cyclotron Resonant heating, in which tungsten is introduced by the laser blow-off technique, have demonstrated that accumulation of tungsten in the central region of the plasma does not take place in these conditions. The measurements obtained are consistent with anomalous transport dominating tungsten transport except in the central region of the plasma where tungsten transport is neoclassical, as previously observed in other devices with dominant neutral beam injection heating, such as JET and ASDEX Upgrade. In contrast to such results, however, the measured scale lengths for plasma temperature and density in the central region of these Alcator C-Mod plasmas, with density profiles relatively flat in the core region due to the lack of core fuelling, are favourable to prevent inter and intra sawtooth tungsten accumulation in this region under dominance of neoclassical transport. Simulations of ITER H-mode plasmas, including both anomalous (modelled by the Gyro-Landau-Fluid code GLF23) and neoclassical transport for main ions and tungsten and with density profiles of similar peaking to those obtained in Alcator C-Mod show that accumulation of tungsten in the central plasma region is also unlikely to occur in stationary ITER H-mode plasmas due to the low fuelling source by the neutral beam injection (injection energy ∼ 1 MeV), which is in good agreement with findings in the Alcator C-Mod experiments.

Effect of neutron irradiation on the microstructure of tungsten

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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.

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

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

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

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.)

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)

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.

High heat flux test of tungsten brazed mock-ups developed for KSTAR divertor

Energy Technology Data Exchange (ETDEWEB)

Song, J.H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, K.M., E-mail: kyungmin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Hong, S.H.; Kim, H.T.; Park, S.H.; Park, H.K.; Ahn, H.J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, S.K.; Lee, D.W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-11-01

The tungsten (W) brazed flat type mock-up which consists of W, OFHC-Cu (oxygen-free high conductive copper) and CuCrZr alloy has been designed for KSTAR divertor in preparation for KSTAR upgrade with 17 MW heating power. For verification of the W brazed mock-up, the high heat flux test is performed at KoHLT-EB (Korea High Heat Load Test Facility-Electron Beam) in KAERI (Korea Atomic Energy Research Institute). Three mock-ups are tested for several thousand thermal cycles with absorbed heat flux up to 5 MW/m{sup 2} for 20 s duration. There is no evidence of the failure at the bonding joints of all mock-ups after HHF test. Finite element analysis (FEA) is performed to interpret the result of the test. As a result, it is considered that the local area in the water is in the subcooled boiling regime.

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%.

Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

Directory of Open Access Journals (Sweden)

Xin Wen Zhang

2015-07-01

Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

Cell density dependence of Microcystis aeruginosa responses to copper algaecide concentrations: Implications for microcystin-LR release.

Science.gov (United States)

Kinley, Ciera M; Iwinski, Kyla J; Hendrikse, Maas; Geer, Tyler D; Rodgers, John H

2017-11-01

Along with mechanistic models, predictions of exposure-response relationships for copper are often derived from laboratory toxicity experiments with standardized experimental exposures and conditions. For predictions of copper toxicity to algae, cell density is a critical factor often overlooked. For pulse exposures of copper-based algaecides in aquatic systems, cell density can significantly influence copper sorbed by the algal population, and consequent responses. A cyanobacterium, Microcystis aeruginosa, was exposed to a copper-based algaecide over a range of cell densities to model the density-dependence of exposures, and effects on microcystin-LR (MC-LR) release. Copper exposure concentrations were arrayed to result in a gradient of MC-LR release, and masses of copper sorbed to algal populations were measured following exposures. While copper exposure concentrations eliciting comparable MC-LR release ranged an order of magnitude (24-h EC50s 0.03-0.3mg Cu/L) among cell densities of 10 6 through 10 7 cells/mL, copper doses (mg Cu/mg algae) were similar (24-h EC50s 0.005-0.006mg Cu/mg algae). Comparisons of MC-LR release as a function of copper exposure concentrations and doses provided a metric of the density dependence of algal responses in the context of copper-based algaecide applications. Combined with estimates of other site-specific factors (e.g. water characteristics) and fate processes (e.g. dilution and dispersion, sorption to organic matter and sediments), measuring exposure-response relationships for specific cell densities can refine predictions for in situ exposures and algal responses. These measurements can in turn decrease the likelihood of amending unnecessary copper concentrations to aquatic systems, and minimize risks for non-target aquatic organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

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

High density, uniformly distributed W/UO2 for use in Nuclear Thermal Propulsion

Science.gov (United States)

Tucker, Dennis S.; Barnes, Marvin W.; Hone, Lance; Cook, Steven

2017-04-01

An inexpensive, quick method has been developed to obtain uniform distributions of UO2 particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO2 particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

Electronic Structure Control of Tungsten Oxide Activated by Ni for Ultrahigh-Performance Supercapacitors.

Science.gov (United States)

Meng, Tian; Kou, Zongkui; Amiinu, Ibrahim Saana; Hong, Xufeng; Li, Qingwei; Tang, Yongfu; Zhao, Yufeng; Liu, Shaojun; Mai, Liqiang; Mu, Shichun

2018-04-17

Tuning the electron structure is of vital importance for designing high active electrode materials. Here, for boosting the capacitive performance of tungsten oxide, an atomic scale engineering approach to optimize the electronic structure of tungsten oxide by Ni doping is reported. Density functional theory calculations disclose that through Ni doping, the density of state at Fermi level for tungsten oxide can be enhanced, thus promoting its electron transfer. When used as electrode of supercapacitors, the obtained Ni-doped tungsten oxide with 4.21 at% Ni exhibits an ultrahigh mass-specific capacitance of 557 F g -1 at the current density of 1 A g -1 and preferable durability in a long-term cycle test. To the best of knowledge, this is the highest supercapacitor performance reported so far in tungsten oxide and its composites. The present strategy demonstrates the validity of the electronic structure control in tungsten oxide via introducing Ni atoms for pseudocapacitors, which can be extended to other related fields as well. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, Consolidation and Characterization of Sol-gel Derived Tantalum-Tungsten Oxide Thermite Composites

Energy Technology Data Exchange (ETDEWEB)

Cervantes, O [Univ. of California, Davis, CA (United States)

2010-06-01

Energetic composite powders consisting of sol-gel (SG) derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the SG derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The SG derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO3) energetic composite was consolidated to a density of 9.17 g·cm-3 or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.

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

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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�

Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate

International Nuclear Information System (INIS)

Liu, Y.H.; Zhang, Y.C.; Jiang, F.; Fu, B.J.; Sun, N.B.

2013-01-01

Tungsten is considered a promising plasma facing armor material for future fusion devices. An electrodeposited metallic tungsten coating from Na 2 WO 4 –WO 3 binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and electro-crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%

Electrodeposition of metallic tungsten coating from binary oxide molten salt on low activation steel substrate

Energy Technology Data Exchange (ETDEWEB)

Liu, Y. H. [School of Materials Science and Engineering, University of Science and Technology BeiJing, Beijing (China); State Nuclear Power Research Institute, Xicheng District, Beijing (China); Zhang, Y.C., E-mail: zycustb@163.com [School of Materials Science and Engineering, University of Science and Technology BeiJing, Beijing (China); Jiang, F.; Fu, B. J.; Sun, N. B. [School of Materials Science and Engineering, University of Science and Technology BeiJing, Beijing (China)

2013-11-15

Tungsten is considered a promising plasma facing armor material for future fusion devices. An electrodeposited metallic tungsten coating from Na{sub 2}WO{sub 4}–WO{sub 3} binary oxide molten salt on low activation steel (LAS) substrate was investigated in this paper. Tungsten coatings were deposited under various pulsed currents conditions at 1173 K in atmosphere. Cathodic current density and pulsed duty cycle were investigated for pulsed current electrolysis. The crystal structure and microstructure of tungsten coatings were characterized by X-ray diffractometry, scanning electron microscopy, and energy X-ray dispersive analysis techniques. The results indicated that pulsed current density and duty cycle significantly influence tungsten nucleation and electro-crystallization phenomena. The average grain size of the coating becomes much larger with increasing cathodic current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with the increasing thickness of coatings; the maximum micro-hardness is 482 HV. The prepared tungsten coatings have a smooth surface, a porosity of less than 1%, and an oxygen content of 0.024 wt%.

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

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.

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.

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

Effect of direct current density on microstructure of tungsten coating electroplated from Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} system

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fan, E-mail: jiangfan1109@163.com; Zhang, Yingchun, E-mail: zycustb@163.com; Sun, Ningbo, E-mail: suningbo682@163.com; Liu, Zhi’ang, E-mail: zhiang_001@163.com

2014-10-30

Highlights: • Tungsten coatings were electroplated from the Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} melt. • Tungsten coating comprised a tooth-like layer and a columnar growth layer. • The average grain size increases as increasing current density. • (2 1 1) Orientation is favored most likely for samples obtained at various durations. • The growth rate of tungsten crystal nucleus is higher than the nucleation rate. - Abstract: Pure tungsten coating with body-centered cubic (bbc) structure was successfully electrodeposited from Na{sub 2}WO{sub 4}-WO{sub 3}-NaPO{sub 3} molten salt at 1153 K in atmosphere. The coatings comprised an inner layer of tooth-like grains and an outer layer of columnar grains with a thin diffusion layer of tungsten in the Cu substrate. The effects of current density and electrodeposition duration on the morphology and microstructure of the coatings were investigated in this paper. With increasing of current density from 50 to 80 mA cm{sup −2}, the grain size of the tungsten coating increased from 7.01 μm to 12.44 μm. With the increase of the current density, the thickness of the coating changed from 25.92 μm to 34.40 μm, and then dropped to 29.72 μm. The preferred orientation of the coatings changed from (2 2 0) to (2 1 1). With the increasing of duration, the grain size and thickness of tungsten coatings increased while the (2 1 1) favored orientation dot not changed. Because of the low current efficiency at long duration of direct current electrodeposition, it should not be suitable for the electroplating of thick tungsten coating.

Amorphous nickel/cobalt tungsten sulfide electrocatalysts for high-efficiency hydrogen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Yang, Lun [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wu, Xinglong, E-mail: hkxlwu@nju.edu.cn [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Department of Physics, NingBo University, NingBo 315001 (China); Zhu, Xiaoshu [Center for Analysis and Testing, Nanjing Normal University, Nanjing 210093 (China); He, Chengyu; Meng, Ming; Gan, Zhixing [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics and Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-06-30

Graphical abstract: - Highlights: • Amorphous nickel/cobalt tungsten sulfides were synthesized by a thermolytic process. • Amorphous NiWS and CoWS could realize hydrogen evolution efficiently. • Ni/Co promotion and annealing alter the porous structure and chemical bonding states. • Active sites on the surface of amorphous WS{sub x} are increased with Ni or Co doping. • Amorphous NiWS and CoWS have immense potentials in water splitting devices. - Abstract: The hydrogen evolution reaction (HER), an appealing solution for future energy supply, requires efficient and inexpensive electrocatalysts with abundant active surface sites. Although crystalline MoS{sub 2} and WS{sub 2} are promising candidates, their activity is dominated by edge sites. Amorphous tungsten sulfide prepared so far lacks the required active sites and its application has thus been hampered. In this work, nickel and cobalt incorporated amorphous tungsten sulfide synthesized by a thermolytic process is demonstrated to enhance the HER efficiency dramatically. The amorphous nickel tungsten sulfide (amorphous NiWS) annealed at 210 °C delivers the best HER performance in this system boasting a Tafel slope of 55 mV per decade and current density of 8.6 mA cm{sup −2} at 250 mV overpotential in a sustained test for 24 h. The introduction of Ni or Co into the catalyst and subsequent thermal treatment alters the porous structure and chemical bonding states thereby increasing the density of active sites on the surface.

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

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)

Deuterium accumulation in tungsten at high fluences

Energy Technology Data Exchange (ETDEWEB)

Zibrov, Mikhail [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); FOM Institute DIFFER, De Zaale 20, 5612 AJ Eindhoven (Netherlands); Balden, Martin; Matej, Matej [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); Bystrov, Kirill; Morgan, Thomas [FOM Institute DIFFER, De Zaale 20, 5612 AJ Eindhoven (Netherlands)

2016-07-01

The data on the deuterium (D) retention in tungsten (W) at high fluences (≥ 10{sup 27} D/m{sup 2}) are scarce and the existing results are contradictory. Since retention in W is known to be flux-dependent, the laboratory experiments addressing this issue should be carried out in reactor-relevant conditions (high fluxes of low-energy ions). In this work the samples made of polycrystalline W were exposed to D plasmas in the linear plasma generator Pilot-PSI at temperatures ranging from 360 K to 1140 K to fluences in the range of 0.3-8.7 x 10{sup 27} D/m{sup 2}. It was observed that at exposure temperatures of 360 K and 580 K the D retention was only slightly dependent on the ion fluence. In addition, the presence of blister-like structures was found after the exposures, and their density and size distributions were also only weakly dependent on the fluence. In the case of exposure at 1140 K no surface modifications of the samples after plasma exposure were detected and the concentrations of retained D were very small. At all temperatures used the total amounts of retained D were smaller compared to those obtained by other researchers at lower ion flux densities, which indicates that the incident ion flux may play an important role in the total D retention in W.

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

Chemically vapor-deposited tungsten: its high temperature strength and ductility

International Nuclear Information System (INIS)

Bryant, W.A.

1977-01-01

The high temperature tensile ductility (as measured by total elongation normal to the growth direction) of chemically vapor-deposited tungsten was found to be significantly greater than previously reported. A correlation was found between ductility and void content. However, voids were found to have essentially no effect on the high temperature strength of this material, which is considerably weaker than powder metallurgy tungsten. (Auth.)

A New Approach to Environmentally Safe Unique Identification of Long-Term Stored Copper Canisters

International Nuclear Information System (INIS)

Chernikova, D.; Axell, K.; Nordlund, A.

2015-01-01

A new approach to environmentally safe unique identification of long-term stored copper canisters is suggested in this paper. The approach is based on the use of a tungstenbased insert placed inside a copper cask between a top iron lid and a copper lid. The insert/label is marked with unique code in a form of binary number, which is implemented as a combination of holes in the tungsten plate. In order to provide a necessary redundancy of the identifier, the tungsten label marked with few identical binary codes. The position of code (i.e., holes in tungsten) corresponds to a predefined placement of the spent fuel assembles in the iron container. This is in order to avoid any non-uniformity of the gamma background at the canister surface caused by a presence of iron-filled spaces between spent nuclear fuel assembles. Due to the use of the tungsten material gamma rays emitted by the spent fuel assembles are collimated in a specific way because of strong attenuation properties of tungsten. As a result, the variation in the gamma-counting rate in a detector array placed on the top of copper lid provides the distribution of the holes in the tungsten insert or in other words the unique identifier. Thus, this way of identification of copper cask do not impair the integrity of the cask and it offers a way that the information about spent nuclear fuel is legible for a time scale up to a few thousands years. (author)

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)

Fabrication of high aspect ratio through-wafer copper interconnects by reverse pulse electroplating

International Nuclear Information System (INIS)

Gu, Changdong; Zhang, Tong-Yi; Xu, Hui

2009-01-01

This study aims to fabricate high aspect ratio through-wafer copper interconnects by a simple reverse pulse electroplating technique. High aspect-ratio (∼18) through-wafer holes obtained by a two-step deep reactive ion etching (DRIE) process exhibit a taper profile, which might automatically optimize the local current density distribution during the electroplating process, thereby achieving void-free high aspect-ratio copper vias

Density function theory study of the adsorption and dissociation of carbon monoxide on tungsten nanoparticles.

Science.gov (United States)

Weng, Meng-Hsiung; Ju, Shin-Pon; Chen, Hsin-Tsung; Chen, Hui-Lung; Lu, Jian-Ming; Lin, Ken-Huang; Lin, Jenn-Sen; Hsieh, Jin-Yuan; Yang, Hsi-Wen

2013-02-01

The adsorption and dissociation properties of carbon monoxide (CO) molecule on tungsten W(n) (n = 10-15) nanoparticles have been investigated by density-functional theory (DFT) calculations. The lowest-energy structures for W(n) (n = 10-15) nanoparticles are found by the basin-hopping method and big-bang method with the modified tight-binding many-body potential. We calculated the corresponding adsorption energies, C-O bond lengths and dissociation barriers for adsorption of CO on nanoparticles. The electronic properties of CO on nanoparticles are studied by the analysis of density of state and charge density. The characteristic of CO on W(n) nanoparticles are also compared with that of W bulk.

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

High strain and strain-rate behaviour of PTFE/aluminium/tungsten mixtures

International Nuclear Information System (INIS)

Addiss, John; Walley, Stephen; Proud, William; Cai Jing; Nesterenko, Vitali

2007-01-01

Conventional drop-weight techniques were modified to accommodate low-amplitude force transducer signals from low-strength, cold isostatically pressed 'heavy' composites of polytetrafluoroethylene, aluminum and tungsten (W). The failure strength, strain and the post-critical behavior of failed samples were measured for samples of different porosity and tungsten grain size. Unusual phenomenon of significantly higher strength (55 MPa) of porous composites (density 5.9 g/cm 3 ) with small W particles ( 3 ) with larger W particles (44 μm) at the same volume content of components was observed. This is attributed to force chains created by a network of small W particles. Interrupted tests at different levels of strain revealed the mechanisms of fracture under dynamic compression

SPS Fabrication of Tungsten-Rhenium Alloys in Support of NTR Fuels Development

International Nuclear Information System (INIS)

Webb, Jonathan A.; Charit, Indrajit; Sparks, Cory; Butt, Darryl P.; Frary, Megan; Carroll, Mark

2011-01-01

Tungsten metal slugs were fabricated via Spark Plasma Sintering (SPS) of powdered metals at temperatures ranging from 1575 K to 1975 K and hold times of 5 minutes to 30 minutes, using powders with an average diameter of 7.8 ?m. Sintered tungsten specimens were found to have relative densities ranging from 83 % to 94 % of the theoretical density for tungsten. Consolidated specimens were also tested for their Vickers Hardness Number (VHN), which was fitted as a function of relative density; the fully consolidated VHN was extrapolated to be 381.45 kg/mm2. Concurrently, tungsten and rhenium powders with average respective diameters of 0.5 ?m and 13.3 ?m were pre-processed either by High-Energy-Ball-Milling (HEBM) or by homogeneous mixing to yield W-25at.%Re mixtures. The powder batches were sintered at temperatures of 1975 K and 2175 K for hold times ranging from 0 minutes to 60 minutes yielding relative densities ranging from 94% to 97%. The combination of HEBM and sintering showed a significant decrease in the inter-metallic phases compared to that of the homogenous mixing and sintering.

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.

The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications

Czech Academy of Sciences Publication Activity Database

Matějíček, Jiří; Kavka, Tetyana; Bertolissi, Gabriele; Ctibor, Pavel; Vilémová, Monika; Mušálek, Radek; Nevrlá, Barbara

2013-01-01

Roč. 22, č. 5 (2013), s. 744-755 ISSN 1059-9630 R&D Projects: GA MPO FR-TI2/702; GA TA ČR TA01010300 Institutional support: RVO:61389021 Keywords : plasma spraying * tungsten * copper * inert gas shrouding * water-argon plasma torch * gas shroud * hybrid plasma torch * influence of spray parameters * nuclear fusion * oxidation Subject RIV: JG - Metallurgy Impact factor: 1.491, year: 2013 http://link.springer.com/content/pdf/10.1007%2Fs11666-013-9895-x.pdf

Tungsten versus depleted uranium for armour-piercing penetrators

International Nuclear Information System (INIS)

Johnson, P.K.

1983-01-01

Tungsten alloys have been widely used in the production of armour-piercing (AP) penetrators for defense purposes for the past 40 years. In recent years, however, depleted uranium (DU) has also been utilised for this application. Both materials exhibit high density and strength, two properties necessary for kinetic-energy projectiles to penetrate armour on tanks and other vehicles. The facts, however, support the view that tungsten can and should be utilised as the primary material for most armour-defeating ordnance applications. (author)

Thermal conductivity of tungsten–copper composites

International Nuclear Information System (INIS)

Lee, Sang Hyun; Kwon, Su Yong; Ham, Hye Jeong

2012-01-01

Highlights: ► We present the temperature dependence of the thermophysical properties for tungsten–copper composite from room temperature to 400 °C. The powders of tungsten–copper were produced by the spray conversion method and the W–Cu alloys were fabricated by the metal injection molding. Thermal conductivity and thermal expansion of tungsten–copper composite was controllable by volume fraction copper. - Abstract: As the speed and degree of integration of semiconductor devices increases, more heat is generated, and the performance and lifetime of semiconductor devices depend on the dissipation of the generated heat. Tungsten–copper alloys have high electrical and thermal conductivities, low contact resistances, and low coefficients of thermal expansion, thus allowing them to be used as a shielding material for microwave packages, and heat sinks for high power integrated circuits (ICs). In this study, the thermal conductivity and thermal expansion of several types of tungsten–copper (W–Cu) composites are investigated, using compositions of 5–30 wt.% copper balanced with tungsten. The tungsten–copper powders were produced using the spray conversion method, and the W–Cu alloys were fabricated via the metal injection molding. The tungsten–copper composite particles were nanosized, and the thermal conductivity of the W–Cu alloys gradually decreases with temperature increases. The thermal conductivity of the W–30 wt.% Cu composite was 238 W/(m K) at room temperature.

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.

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.

Density evaluation of remotely-supplied hydrogen radicals produced via tungsten filament method for SiCl4 reduction

Science.gov (United States)

Zohra Dahmani, Fatima; Okamoto, Yuji; Tsutsumi, Daiki; Ishigaki, Takamasa; Koinuma, Hideomi; Hamzaoui, Saad; Flazi, Samir; Sumiya, Masatomo

2018-05-01

Effect of the hydrogen radical on the reduction of a silicon tetrachloride (SiCl4) source was studied. The hydrogen radicals were generated using a tungsten (W) filament in a generation chamber, and were remotely supplied to another reaction chamber. The density of the hydrogen radical was estimated from the optical transmittance of 600-nm-wavelength light through phosphate glass doped with tungsten oxide (WO3). Lifetime of the hydrogen radical seemed sufficiently long, and its density as supplied to the reaction chamber was estimated to be on the order of 1012 cm‑3. Signal intensity of the peak corresponding to SiCl4 (m/z = 170) detected by quadrupole-mass measurement was confirmed to decrease owing to the reaction with the remotely-supplied hydrogen radical. This indicates the possibility that chemically-stable SiCl4, as one of the by-products of the Siemens process, can be reduced to produce silicon.

Yield strength of molybdenum, tantalum and tungsten at high strain rates and very high temperatures

International Nuclear Information System (INIS)

Škoro, G.P.; Bennett, J.R.J.; Edgecock, T.R.; Booth, C.N.

2012-01-01

Highlights: ► New experimental data on the yield strength of molybdenum, tantalum and tungsten. ► High strain rate effects at record high temperatures (up to 2700 K). ► Test of the consistency of the Zerilli–Armstrong model at very high temperatures. - Abstract: Recently reported results of the high strain rate, high temperature measurements of the yield strength of tantalum and tungsten have been analyzed along with new experimental results on the yield strength of molybdenum. Thin wires are subjected to high stress by passing a short, fast, high current pulse through a thin wire; the amplitude of the current governs the stress and the repetition rate of the pulses determines the temperature of the wire. The highest temperatures reached in the experiments were 2100 °C (for molybdenum), 2250 °C (for tantalum) and 2450 °C (for tungsten). The strain-rates in the tests were in the range from 500 to 1500 s −1 . The parameters for the constitutive equation developed by Zerilli and Armstrong have been determined from the experimental data and the results have been compared with the data obtained at lower temperatures. An exceptionally good fit is obtained for the deformation of tungsten.

Micro/nano composited tungsten material and its high thermal loading behavior

Energy Technology Data Exchange (ETDEWEB)

Fan, Jinglian, E-mail: fjl@csu.edu.cn; Han, Yong; Li, Pengfei; Sun, Zhiyu; Zhou, Qiang

2014-12-15

Tungsten (W) is considered as promising candidate material for plasma facing components (PFCs) in future fusion reactors attributing to its many excellent properties. Current commercial pure tungsten material in accordance with the ITER specification can well fulfil the performance requirements, however, it has defects such as coarse grains, high ductile–brittle transition temperature (DBTT) and relatively low recrystallization temperature compared with its using temperature, which cannot meet the harsh wall loading requirement of future fusion reactor. Grain refinement has been reported to be effective in improving the thermophysical and mechanical properties of W. In this work, rare earth oxide (Y{sub 2}O{sub 3}/La{sub 2}O{sub 3}) and carbides (TiC/ZrC) were used as dispersion phases to refine W grains, and micro/nano composite technology with a process of “sol gel – heterogeneous precipitation – spray drying – hydrogen reduction – ordinary consolidation sintering” was invented to introduce these second-phase particles uniformly dispersed into W grains and grain-boundaries. Via this technology, fine-grain W materials with near-full density and relatively high mechanical properties compared with traditional pure W material were manufactured. Preliminary transient high-heat flux tests were performed to evaluate the thermal response under plasma disruption conditions, and the results show that the W materials prepared by micro/nano composite technology can endure high-heat flux of 200 MW/m{sup 2} (5 ms)

Effect of high-flux H/He plasma exposure on tungsten damage due to transient heat loads

Energy Technology Data Exchange (ETDEWEB)

De Temmerman, G., E-mail: gregory.detemmerman@iter.org [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregion Cluster, Postbus 1207, 3430BE Nieuwegein (Netherlands); ITER Organization, Route de Vinon sur Verdon, CS 90 096, 13067 Saint Paul-lez-Durance (France); Morgan, T.W.; Eden, G.G. van; Kruif, T. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregion Cluster, Postbus 1207, 3430BE Nieuwegein (Netherlands); Wirtz, M. [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research – Microstructure and Properties of Materials (IEK-2), EURATOM Association, 52425 Jülich (Germany); Matejicek, J.; Chraska, T. [Institute of Plasma Physics, Association EURATOM-IPP, CR Prague (Czech Republic); Pitts, R.A. [ITER Organization, Route de Vinon sur Verdon, CS 90 096, 13067 Saint Paul-lez-Durance (France); Wright, G.M. [MIT Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

2015-08-15

The thermal shock behaviour of tungsten exposed to high-flux plasma is studied using a high-power laser. The cases of laser-only, sequential laser and hydrogen (H) plasma and simultaneous laser plus H plasma exposure are studied. H plasma exposure leads to an embrittlement of the material and the appearance of a crack network originating from the centre of the laser spot. Under simultaneous loading, significant surface melting is observed. In general, H plasma exposure lowers the heat flux parameter (F{sub HF}) for the onset of surface melting by ∼25%. In the case of He-modified (fuzzy) surfaces, strong surface deformations are observed already after 1000 laser pulses at moderate F{sub HF} = 19 MJ m{sup −2} s{sup −1/2}, and a dense network of fine cracks is observed. These results indicate that high-fluence ITER-like plasma exposure influences the thermal shock properties of tungsten, lowering the permissible transient energy density beyond which macroscopic surface modifications begin to occur.

In Situ Synthesis of Tungsten-Doped SnO2 and Graphene Nanocomposites for High-Performance Anode Materials of Lithium-Ion Batteries.

Science.gov (United States)

Wang, Shuai; Shi, Liyi; Chen, Guorong; Ba, Chaoqun; Wang, Zhuyi; Zhu, Jiefang; Zhao, Yin; Zhang, Meihong; Yuan, Shuai

2017-05-24

The composite of tungsten-doped SnO 2 and reduced graphene oxide was synthesized through a simple one-pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO 2 was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO 2 agglomeration and volume expansion could be also avoided because the tungsten-doped SnO 2 nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO 2 and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g -1 at 0.1 A g -1 after 100 cycles. It still remained at 776 mA h g -1 after 2000 cycles at the current density of 1A g -1 .

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.

High density, uniformly distributed W/UO{sub 2} for use in Nuclear Thermal Propulsion

Energy Technology Data Exchange (ETDEWEB)

Tucker, Dennis S., E-mail: dr.dennis.tucker@nasa.gov [EM32, MSFC, Al 35812 (United States); Barnes, Marvin W. [EM32, MSFC, Al 35812 (United States); Hone, Lance; Cook, Steven [Center for Space Nuclear Research, Idaho Falls, ID 83401 (United States)

2017-04-01

An inexpensive, quick method has been developed to obtain uniform distributions of UO{sub 2} particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO{sub 2} particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

Numerical simulation of the internal stresses of thick tungsten coating deposited by vacuum plasma spraying on copper substrate

International Nuclear Information System (INIS)

Salito, A.; Tului, M.; Casadei, F.

1998-01-01

Several Divertor components in the new generation of nuclear fusion reactors need to be protected against ion sputtering. Particularly copper based (Cu) material is very sensitive to this sputtering process. A solution to overcome such component wear and plasma contamination is to protect the copper substrate with a thick tungsten (W) functional coating. The main difficulty to produce such components is the significant difference in the coating thermomechanical properties between W and Cu. The Vacuum Plasma Spraying coating process (VPS) is a very flexible new economical way to find a solution to the above problem. To optimise the adhesion and stress release properties between the Cu-alloy substrate and the W coating, it is possible to deposit an interlayer as a bond coat between both materials. The aim of this study is to determine the maximum of the residual stresses located between the Cu substrate and the W coating using finite element analysis. The results have been used to select different types of bond coat for the experimental development of thick W coating (>3 mm) on to mock-ups for the Divertor Channel of the ITER project. (author)

Study on the high temperature crack resistance of tungsten

International Nuclear Information System (INIS)

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

1983-01-01

The possibility of a multiple use of tungsten specimens in crack resistance tests in the temperature range of 600-2000 deg C is studied. It is established experimentally that the minimum length of growth of a main crack is 1x10 -4 m for the most effective repeated use of specimens. A flow diagram of mechanical tests is suggested for investigating high temperature tungsten crack resistance and estimating the degree of weakening the grain-boundary bond

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

A fracture mechanics study of tungsten failure under high heat flux loads

International Nuclear Information System (INIS)

Li, Muyuan

2015-01-01

The performance of fusion devices is highly dependent on plasma-facing components. Tungsten is the most promising candidate material for armors in plasma-facing components in ITER and DEMO. However, the brittleness of tungsten below the ductile-to-brittle transition temperature is very critical to the reliability of plasma-facing components. In this work, thermo-mechanical and fracture behaviors of tungsten are predicted numerically under fusion relevant thermal loadings.

Electro-chemically-based technologies for processing of tungsten components in fusion technology

International Nuclear Information System (INIS)

Holstein, N.; Konys, J.; Krauss, W.; Lorenz, J.

2010-01-01

In fusion technology layers and bulk components fabricated from tungsten and W-alloys are used as functional materials, e.g. as coatings of blanket modules or T-permeation barriers and also as structural components in a He-cooled divertor. Their application under high heat loads and temperatures is besides manufacturing, also challenging regarding joining, caused e.g. by expansion mismatches in combination with steel or other diffusion issues. Driven by these needs, electro-chemically-based technologies were analyzed concerning their advantages in processing in the fields of soft structuring of tungsten alloys and in deposition of functional scales. The Electro-Chemistry (EC) of tungsten is characterized by its affection to build up passivation layers in aqueous media during the initial oxidation, which is the result of an unavoidable basic electrochemical reaction with water (W + 3H 2 O → WO 3 + 3H 2 ), although the element standard potential is situated between common EC material like iron and copper. (orig.)

Fracture and Residual Characterization of Tungsten Carbide Cobalt Coatings on High Strength Steel

National Research Council Canada - National Science Library

Parker, Donald S

2003-01-01

Tungsten carbide cobalt coatings applied via high velocity oxygen fuel thermal spray deposition are essentially anisotropic composite structures with aggregates of tungsten carbide particles bonded...

Experimental study of tungsten transport properties in T-10 plasma

Science.gov (United States)

Krupin, V. A.; Nurgaliev, M. R.; Klyuchnikov, L. A.; Nemets, A. R.; Zemtsov, I. A.; Dnestrovskij, A. Yu.; Sarychev, D. V.; Lisitsa, V. S.; Shurygin, V. A.; Leontiev, D. S.; Borschegovskij, A. A.; Grashin, S. A.; Ryjakov, D. V.; Sergeev, D. S.; Mustafin, N. A.; Trukhin, V. M.; Solomatin, R. Yu.; Tugarinov, S. N.; Naumenko, N. N.

2017-06-01

First experimental results of tungsten transport investigation in OH and ECRH plasmas in the T-10 tokamak with W-limiter and movable Li-limiter are presented. It is shown that tungsten tends to accumulate (a joint process of cumulation and peaking) near the plasma axis in ohmic regimes. The cumulation of W is enhanced in discharges with high values of the parameter γ ={{\\bar{n}}\\text{e}}\\centerdot {{\\bar{Z}}\\text{eff}}\\centerdot I\\text{pl}-1.5 that coincides with accumulation conditions of light and medium impurities in T-10 plasmas. Experiments with Li-limiter show the immeasurable level of Li3+ (0.3-0.5% of n e) of T-10 CXRS diagnostics because of the low inflow of Li with respect to other light impurities. Nevertheless, the strong influence of lithium on inflow of light and tungsten impurities is observed. In discharges with lithized walls, vanishing of light impurities occurs and values of {{Z}\\text{eff}}≈ 1 are obtained. It is also shown that the tungsten density in the plasma center decreases by 15 to 20 times while the W inflow reduces only by 2 to 4 times. In lithized discharges with high γ, the flattening of the tungsten density profile occurs and its central concentration decreases up to 10 times during the on-axis ECRH. This effect is observed together with the increase of the W inflow by 3 to 4 times at the ECRH stage.

In-situ tomographic observation of crack formation and propagation in tungsten materials in the framework of FEMaS-CA

International Nuclear Information System (INIS)

Riesch, J.; Linsmeier, C.; Nielsen, S.F.

2010-01-01

The EU has funded the Fusion Energy Materials Science project Coordination Action (FEMaSCA) with the intension to utilize the know-how in the materials community to help overcome the material science problems with fusion related materials. In this framework three different material concepts, tungsten-copper-composite (W/Cu), vacuum plasma sprayed tungsten (VPSW), and tungsten-fiber/tungsten-matrix-composite (W f /W m ) were investigated by means of insitu tomography during mechanical testing. The measuring campaign was conducted at the high energy beamtine ID ISA at the European Synchrotron Radiation Facility (ESRF) in Grenoble. A tensile testing machine was used to perform displacement controlled tension tests. At the end of each well defined displacement step a tomogram was taken. Tomographic reconstructions were successfully produced of samples with high tungsten content and sample diameters up to 1 mm. Force-displacement curves were measured during loading to complete fracture. Crack propagation could he observed in the tomographic reconstructions. This paper describes the first results with special focus on the experimental work and the role of FEMaS-CA. (Author)

Differential reflectometry of thin film metal oxides on copper, tungsten, molybdenum and chromium

International Nuclear Information System (INIS)

Urban, F.K. III; Hummel, R.E.; Verink, E.D. Jr.

1982-01-01

A differential reflectometry study was undertaken to investigate the characteristics of thin oxide films on metal substrates. The oxides were produced by heating pure metals of copper, tungsten, molybdenum and chromium in dry oxygen. A new 'halfpolishing' technique was applied to obtain specimens with a step in oxide thickness in order to make them suitable for differential reflectometry. It was found that oxides formed this way yielded the same differential reflectograms as by electrochemical oxidation. A mathematical model involving the interaction of light with a thin corrosion product on metal substrates was applied to generate computer calculated differential reflectograms utilizing various optical constants and thicknesses of the assumed film. Three different thickness ranges have been identified. (a) For large film thicknesses, the differential reflectograms are distinguished by a sequence of interference peaks. (b) If the product of thickness and refraction index of the films is smaller than about 40 nm, no interference peaks are present. Any experimentally observed peaks in differential reflectograms of these films are caused entirely by electron interband transitions. (c) In an intermediate thickness range, superposition of interference and interband peaks are observed. (author)

Dynamic control of low-Z material deposition and tungsten erosion by strike point sweeping on DIII-D

Directory of Open Access Journals (Sweden)

J. Guterl

2017-08-01

Full Text Available Carbon deposition on tungsten between ELMs was investigated in DIII-D in semi-attached/detached H-mode plasma conditions using fixed outer strike point (OSP positions. Carbon deposition during plasma exposure of tungsten was monitored in-situ by measuring the reflectivity of the tungsten sample surface. No significant carbon deposition, i.e., without strong variations of the reflectivity, was observed during these experiments including discharges at high densities. In contrast, ERO modeling predicts a significant carbon deposition on the tungsten surface for those high density plasma conditions. The surface reflectivity decreases with methane injection, consistent with increased carbon coverage, as expected. The sweeping of OSP leads to a pronounced increase of the surface reflectivity, suggesting that the strike point sweeping may provide an effective means to remove carbon coating from tungsten surface. The ERO modeling however predicts again a regime of carbon deposition for these experiments. The discrepancies between carbon deposition regime predicted by the ERO model and the experimental observations suggest that carbon erosion during ELMs may significantly affect carbon deposition on tungsten.

Bio-availability of tungsten in the vicinity of an abandoned mine in the English Lake District and some potential health implications

International Nuclear Information System (INIS)

Wilson, Bob; Pyatt, F. Brian

2006-01-01

This research addresses the occurrence, detection and possible fate of tungsten in the vicinity of an abandoned mine in the English Lake District. Aqua regia extraction and subsequent analysis of spoil and vegetation confirmed the presence of tungsten and other heavy metals. Spoil samples examined were last worked almost 100 years ago and the concentrations of copper, zinc, tungsten and arsenic detected demonstrate the environmental persistence of these metals in an area of relatively high rainfall. The bioaccumulation of tungsten by two species of plants is indicated and partitioning within different tissues of Calluna vulgaris is demonstrated. Mechanisms relating to mobility and speciation of the metals present were explored using sequential and single stage extraction systems. Tungsten appears to be relatively immobile when subjected to sequential extraction but increased bioavailability is indicated when single stage extraction using EDTA is employed

Investigations on microstructure, electrical and magnetic properties of copper spinel ferrite with WO3 addition for applications in the humidity sensors

Science.gov (United States)

Tudorache, Florin

2018-04-01

In the present study we report the structural, electrical, magnetic and humidity characteristics of copper ferrite with different percent on tungsten trioxide addition. The aim of this study was to obtain more stable and sensitive active materials for humidity sensors. In order to highlight the influence of tungsten on the structural, electrical and magnetic properties, the ferrite samples were fabricated via sol-gel self-combustion method and sintered for 30 min at 1000 °C with percent between 0 and 20% tungsten trioxide additions. The X-ray diffraction investigations showed the copper ferrite phase composition. The scanning electron microscopy revealed the influence of the substitution on characteristics of the crystallites and the profilometry showed the surface topography of samples. The investigation was focused on the variation of permittivity and electrical conductivity, in relation with tungsten trioxide addition, frequency and humidity. We have also, investigated the relevant magnetic characteristics of the copper ferrite material by highlighting the influence of tungsten trioxide addition on to Curie temperature and the permeability frequency characteristics. The data suggests that the copper ferrite with tungsten trioxide addition can be used as active material for humidity sensors.

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.

Tungsten and carbon surface change under high dose plasma exposure

International Nuclear Information System (INIS)

Martynenko, Y.V.; Khripunov, B.I.; Petrov, V.B.

2009-01-01

Study of surface composition dynamics has been made on the LENTA linear plasma simulator. Experiments have been made on tungsten and carbon materials subjected to steady-state plasma exposure. The achieved ion doses on the surface were 10 21 ion cm -2 . WL 10 tungsten containing 1% of La2O3 oxide and titanium-doped graphite RG-T were studied. The following experimental conditions were varied in these experiments: energy of ions, surface temperature, working gas. Irradiations of tungsten WL 10 were executed in deuterium plasma at low ion energies (about 20 eV) and at 200 eV for temperatures below 340 K. Graphite RG-T was exposed at 1300 K. Elevated surface temperature (about 1050K) was also characteristic of experiments on tungsten sample under nitrogen plasma impact (simulated inter-ELMs condition). Surface microstructure modification has been observed and surface composition changes were found on the materials showing influence of high dose plasma irradiations on element redistribution in the near surface layers. (author)

The high temperature impact response of tungsten and chromium

Science.gov (United States)

Zaretsky, E. B.; Kanel, G. I.

2017-09-01

The evolution of elastic-plastic shock waves has been studied in pure polycrystalline tungsten and chromium at room and elevated temperatures over propagation distances ranging from 0.05 to 3 mm (tungsten) and from 0.1 to 2 mm (chromium). The use of fused silica windows in all but one experiment with chromium and in several high temperature experiments with tungsten led to the need for performing shock and optic characterization of these windows over the 300-1200 K temperature interval. Experiments with tungsten and chromium samples showed that annealing of the metals transforms the initial ramping elastic wave into a jump-like wave, substantially increasing the Hugoniot elastic limits of the metals. With increased annealing time, the spall strength of the two metals slightly increases. Both at room and at high temperatures, the elastic precursor in the two metals decays in two distinct regimes. At propagation distances smaller than ˜1 mm (tungsten) or ˜0.5 mm (chromium), decay is fast, with the dislocation motion and multiplication being controlled by phonon viscous drag. At greater distances, the rate of decay becomes much lower, with control of the plastic deformation being passed to the thermally activated generation and motion of dislocation double-kinks. The stress at which this transition takes place virtually coincides with the Peierls stress τP of the active glide system. Analysis of the annealing effects in both presently and previously studied BCC metals (i.e., Ta, V, Nb, Mo, W, and Cr) and of the dependencies of their normalized Peierls stresses τP(θ) /τP(0 ) on the normalized temperature θ=T /Tm allows one to conclude that the non-planar, split into several glide planes, structure of the dislocation core in these metals is mainly responsible for their plastic deformation features.

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)

Concentration dependent hydrogen diffusion in tungsten

Energy Technology Data Exchange (ETDEWEB)

Ahlgren, T., E-mail: tommy.ahlgren@helsinki.fi; Bukonte, L.

2016-10-15

The diffusion of hydrogen in tungsten is studied as a function of temperature, hydrogen concentration and pressure using Molecular Dynamics technique. A new analysis method to determine diffusion coefficients that accounts for the random oscillation of atoms around the equilibrium position is presented. The results indicate that the hydrogen migration barrier of 0.25 eV should be used instead of the presently recommended value of 0.39 eV. This conclusion is supported by both experiments and density functional theory calculations. Moreover, the migration volume at the saddle point for H in W is found to be positive: ΔV{sub m} ≈ 0.488 Å{sup 3}, leading to a decrease in the diffusivity at high pressures. At high H concentrations, a dramatic reduction in the diffusion coefficient is observed, due to site blocking and the repulsive H-H interaction. The results of this study indicates that high flux hydrogen irradiation leads to much higher H concentrations in tungsten than expected. - Highlights: • The recommended value of 0.39 eV for the H in W migration barrier should be changed to 0.25 eV. • The random oscillation of atoms around the equilibrium position can be dealt with in diffusion simulations. • Hydrogen diffusion in tungsten is highly concentration dependent.

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

Effect of some structural parameters on high-temperature crack resistance of tungsten

International Nuclear Information System (INIS)

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

1984-01-01

The paper presents results of physicomechanical studied in high-temperature crack resistance of tungsten produced by powder metallurgy methods. It is shown that at high temperatures (>2000 deg C) a structure is formed in the material and fails at stresses independent of temperature. It is found that high-temperature tungsten crack resistance is affected neighter by changes in the effictive grain size, nor by appearance of grain-boundary microcraks in the material under high-temperature action

High current density magnets for INTOR and TIBER

International Nuclear Information System (INIS)

Miller, J.R.; Henning, C.D.; Kerns, J.A.; Slack, D.S.; Summers, L.T.; Zbasnik, J.P.

1986-12-01

The adoption of high current density, high field, superconducting magnets for INTOR and TIBER would prove beneficial. When combined with improved radiation tolerance of the magnets to minimize the inner leg shielding, a substantial reduction in machine dimensions and capital costs can be achieved. Fortunately, cable-in-conduit conductors (CICC) which are capable of the desired enhancements are being developed. Because conductor stability in a CICC depends more on the trapped helium enthalpy, rather than the copper resistivity, higher current densities of the order of 40 A/mm 2 at 12 T are possible. Radiation damage to the copper stabilizer is less important because the growth in resistance is a second-order effect on stability. Such CICC conductors lend themselves naturally to niobium-tin utilization, with the benefits of the high current-sharing temperature of this material being taken to advantage in absorbing radiation heating. When the helium coolant is injected at near the critical pressure, Joule-Thompson expansion in the flow path tends to stabilize the fluid temperature at under 6 K. Thus, higher fields, as well as higher current densities, can be considered for INTOR or TIBER

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

Copper nitrate redispersion to arrive at highly active silica-supported copper catalysts

NARCIS (Netherlands)

Munnik, P.|info:eu-repo/dai/nl/328228524; Wolters, M.|info:eu-repo/dai/nl/304829560; Gabrielsson, A.; Pollington, S.D.; Headdock, G.; Bitter, J.H.|info:eu-repo/dai/nl/160581435; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

2011-01-01

In order to obtain copper catalysts with high dispersions at high copper loadings, the gas flow rate and gas composition was varied during calcination of silica gel impregnated with copper nitrate to a loading of 18 wt % of copper. Analysis by X-ray diffraction (XRD), N2O chemisorption, and

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

Deepening of floating potential for tungsten target plate on the way to nanostructure formation

International Nuclear Information System (INIS)

Takamura, Shuichi; Miyamoto, Takanori; Ohno, Noriyasu

2010-01-01

Deepening of floating potential has been observed on the tungsten target plate immersed in high-density helium plasma with hot electron component on the way to nanostructure formation. The physical mechanism is thought to be a reduction of secondary electron emission from such a complex nano fiber-form structure on the tungsten surface. (author)

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.

Near UV-visible line emission from tungsten highly-charged ions in Large Helical Device

International Nuclear Information System (INIS)

Kato, D.; Sakaue, H.A.; Murakami, I.; Goto, M.; Oishi, T.; Morita, S.; Fujii, K.; Nakamura, N.; Koike, F.; Sasaki, Akira; Ding, X.-B.; Dong, C.-Z.

2015-01-01

Wavelengths of emission lines from tungsten highly-charged ions have been precisely measured in near UV-visible range (320 - 356 nm and 382 - 402 nm) at Large Helical Device (LHD) by tungsten pellet injection. The tungsten emission lines were assigned based on its line-integrated intensity profiles on a poloidal cross section. The ground-term magnetic-dipole (M1) lines of W 26+,27+ and an M1 line of a metastable excited state of W 28+ , whose wavelengths have been determined by measurements using electron-beam-ion-traps (EBITs), are identified in the LHD spectra. The present results partially compliment wavelength data of tungsten highly-charged ions in the near UV-visible range. (author)

Mechanical and corrosion behaviors of developed copper-based metal matrix composites

Science.gov (United States)

Singh, Manvandra Kumar; Gautam, Rakesh Kumar; Prakash, Rajiv; Ji, Gopal

2018-03-01

This work investigates mechanical properties and corrosion resistances of cast copper-tungsten carbide (WC) metal matrix composites (MMCs). Copper matrix composites have been developed by stir casting technique. Different sizes of micro and nano particles of WC particles are utilized as reinforcement to prepare two copper-based composites, however, nano size of WC particles are prepared by high-energy ball milling. XRD (X-rays diffraction) characterize the materials for involvement of different phases. The mechanical behavior of composites has been studied by Vickers hardness test and compression test; while the corrosion behavior of developed composites is investigated by electrochemical impedance spectroscopy in 0.5 M H2SO4 solutions. The results show that hardness, compressive strength and corrosion resistance of copper matrix composites are very high in comparison to that of copper matrix, which attributed to the microstructural changes occurred during composite formation. SEM (Scanning electron microscopy) reveals the morphology of the corroded surfaces.

Tungsten nano-tendril growth in the Alcator C-Mod divertor

International Nuclear Information System (INIS)

Wright, G.M.; Brunner, D.; Labombard, B.; Lipschultz, B.; Terry, J.L.; Whyte, D.G.; Baldwin, M.J.; Doerner, R.P.

2012-01-01

Growth of tungsten nano-tendrils (‘fuzz’) has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The thickness of the individual nano-tendrils (50–100 nm) and the depth of the layer (600 ± 150 nm) are consistent with observations from experiments on linear plasma devices. The observation of tungsten fuzz in a tokamak may have important implications for material erosion, dust formation, divertor lifetime and tokamak operations in next-step devices. (letter)

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

Spectroscopic Investigations of Highly Charged Tungsten Ions - Atomic Spectroscopy and Fusion Plasma Diagnostics

Energy Technology Data Exchange (ETDEWEB)

Clementson, Joel [Lund Univ. (Sweden)

2010-05-01

The spectra of highly charged tungsten ions have been investigated using x-ray and extreme ultraviolet spectroscopy. These heavy ions are of interest in relativistic atomic structure theory, where high-precision wavelength measurements benchmark theoretical approaches, and in magnetic fusion research, where the ions may serve to diagnose high-temperature plasmas. The work details spectroscopic investigations of highly charged tungsten ions measured at the Livermore electron beam ion trap (EBIT) facility. Here, the EBIT-I and SuperEBIT electron beam ion traps have been employed to create, trap, and excite tungsten ions of M- and L-shell charge states. The emitted spectra have been studied in high resolution using crystal, grating, and x-ray calorimeter spectrometers. In particular, wavelengths of n = 0 M-shell transitions in K-like W⁵⁵⁺ through Ne-like W⁶⁴⁺, and intershell transitions in Zn-like W⁴⁴⁺ through Co-like W⁴⁷⁺ have been measured. Special attention is given to the Ni-like W46+ ion, which has two strong electric-dipole forbidden transitions that are of interest for plasma diagnostics. The EBIT measurements are complemented by spectral modeling using the Flexible Atomic Code (FAC), and predictions for tokamak spectra are presented. The L-shell tungsten ions have been studied at electron-beam energies of up to 122 keV and transition energies measured in Ne-like W⁶⁴⁺ through Li-like W⁷¹⁺. These spectra constitute the physics basis in the design of the ion-temperature crystal spectrometer for the ITER tokamak. Tungsten particles have furthermore been introduced into the Sustained Spheromak Physics Experiment (SSPX) spheromak in Livermore in order to investigate diagnostic possibilities of extreme ultraviolet tungsten spectra for the ITER divertor. The spheromak measurement and spectral modeling using FAC suggest that tungsten ions in charge states around Er-like W⁶⁺ could be useful for

Preliminary result on quantitative analysis using Zn-like tungsten EUV spectrum in Large Helical Device

International Nuclear Information System (INIS)

Morita, Shigeru; Dong, Chunfeng; Wang, Erhui

2013-01-01

Tungsten study through visible, vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) spectroscopy has been recently started in Large Helical Device (LHD) for developing the diagnostic method in International Thermonuclear Experimental Reactor (ITER) and understanding the tungsten transport in helical system. In order to study the tungsten spectra from core plasmas of LHD, several tungsten spectra are observed in EUV range by injecting a carbon pellet with tungsten. Zn-like tungsten spectrum with 4p-4s transition is clearly identified at 60.9Å in high-temperature phase (T_e ≥ 2.3 keV) of NBI discharges in addition to several unresolved transition arrays with 6g-4f, 5g-4f, 5f-4d, 5g-4f, 4f-4d and 4d-4p transitions in range of 10-70Å. Radial profile of the Zn-like tungsten is also successfully observed with enough intensity in order of 10"1"6 photons.cm"-"2.s"-"1. The radial emissivity profile reconstructed from the chord-integrated intensity profile is analyzed with combination of HULLAC code for emission coefficient calculation of the Zn-like transition and impurity transport code included ADPAK code for calculation of ionization and recombination rate coefficients. Thus, a total tungsten ion density of 3.5x10"1"0 cm"-"3 at the plasma center is reasonably obtained in discharge with central electron density of 4x10"1"3 cm"-"3 as the first experimental trial. The present result demonstrates that the Zn-like 4p-4s transition is applicable to the tungsten diagnostics in high-temperature plasmas. (author)

Solid state consolidation nanocrystalline copper-tungsten using cold spray

Energy Technology Data Exchange (ETDEWEB)

Hall, Aaron Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sarobol, Pylin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Argibay, Nicolas [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clark, Blythe [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Diantonio, Christopher [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-01

It is well known that nanostructured metals can exhibit significantly improved properties compared to metals with conventional grain size. Unfortunately, nanocrystalline metals typically are not thermodynamically stable and exhibit rapid grain growth at moderate temperatures. This severely limits their processing and use, making them impractical for most engineering applications. Recent work has shown that a number of thermodynamically stable nanocrystalline metal alloys exist. These alloys have been prepared as powders using severe plastic deformation (e.g. ball milling) processes. Consolidation of these powders without compromise of their nanocrystalline microstructure is a critical step to enabling their use as engineering materials. We demonstrate solid-state consolidation of ball milled copper-tantalum nanocrystalline metal powder using cold spray. Unfortunately, the nanocrystalline copper-tantalum powder that was consolidated did not contain the thermodynamically stable copper-tantalum nanostructure. Nevertheless, this does this demonstrates a pathway to preparation of bulk thermodynamically stable nanocrystalline copper-tantalum. Furthermore, it demonstrates a pathway to additive manufacturing (3D printing) of nanocrystalline copper-tantalum. Additive manufacturing of thermodynamically stable nanocrystalline metals is attractive because it enables maximum flexibility and efficiency in the use of these unique materials.

High energy density matter issues related to future circular collider. Simulations of full beam impact with a solid copper cylindrical target

Energy Technology Data Exchange (ETDEWEB)

Tahir, N.A. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Burkart, F.; Schmidt, R.; Wollmann, D. [CERN-AB, Geneva (Switzerland); Shutov, A. [Institute of Problems of Chemical Physics, Chernogolovka (Russian Federation); Piriz, A.R. [E.T.S.I. Industrials, University of Castilla-La Mancha, Ciudad Real (Spain)

2017-11-15

This paper presents numerical simulations of the thermodynamic and hydrodynamic response of a solid copper cylindrical target that is subjected to the full impact of one future circular collider (FCC) ultra-relativistic proton beam. The target is facially irradiated so that the beam axis coincides with the cylinder axis. The simulations have been carried out employing an energy deposition code, FLUKA, and a 2D hydrodynamic code, BIG2, iteratively. The simulations show that, although the static range of a single FCC proton and its shower in solid copper is ∝1.5 m, the full beam may penetrate up to 350 m into the target as a result of hydrodynamic tunnelling. Moreover, simulations also show that a major part of the target is converted into high energy density (HED) matter, including warm dense matter (WDM) and strongly coupled plasma. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The chemistry and structure of nickel–tungsten coatings obtained by pulse galvanostatic electrodeposition

International Nuclear Information System (INIS)

Argañaraz, M.P. Quiroga; Ribotta, S.B.; Folquer, M.E.; Zelaya, E.; Llorente, C.; Ramallo-López, J.M.; Benítez, G.; Rubert, A.; Gassa, L.M.; Vela, M.E.; Salvarezza, R.C.

2012-01-01

A detailed characterization of electrodeposited Ni-W coatings prepared by pulse electrodeposition on steel and copper substrates is presented. The coatings were obtained at high current pulse frequency and show high microhardness and absence of brittleness. The surface of the coating consists of nanometer sized crystals forming a cauliflower-like structure protected by a mixture of nickel and tungsten oxides. The cauliflower structure is preserved into the bulk coating that exhibits an average composition ≈70 at% Ni-30 at% W. Different phases are observed in the bulk structure: a W-rich amorphous phase (≈40%) and Ni-rich crystalline phases (≈60%). The crystalline phases consist of crystalline domains ≈7 nm in size of Ni(W) (fcc) solid solution (12 at% W content) and a minor Ni 4 W component (less than 10%). The amorphous phase exhibits a less compact Ni-W structure where some amount of C could also be present. Oxidized W species cannot be detected in the bulk coating, thus discarding the presence of significant amounts of tungsten carbide, tungstates or citrate–tungsten complexes. Our results shed light on controversial points related to the chemical composition and demonstrate the complex structure of this system.

A new equation of state for porous materials with ultra-low densities

CERN Document Server

Geng Hua Yun; Wu Qiang

2002-01-01

A thermodynamic equation of state is derived which is appropriate for investigating the thermodynamic variations along isobaric paths to predict compression behaviours of porous materials. This equation-of-state model is tested on porous iron, copper, lead and tungsten with different initial densities. The calculated Hugoniots are in good agreement with the corresponding experimental data published previously. This shows that this model can satisfactorily predict the Hugoniots of porous materials with wide porosity and pressure ranges.

Copper hexacyanoferrate battery electrodes with long cycle life and high power

KAUST Repository

Wessells, Colin D.; Huggins, Robert A.; Cui, Yi

2011-01-01

Short-term transients, including those related to wind and solar sources, present challenges to the electrical grid. Stationary energy storage systems that can operate for many cycles, at high power, with high round-trip energy efficiency, and at low cost are required. Existing energy storage technologies cannot satisfy these requirements. Here we show that crystalline nanoparticles of copper hexacyanoferrate, which has an ultra-low strain open framework structure, can be operated as a battery electrode in inexpensive aqueous electrolytes. After 40,000 deep discharge cycles at a 17g-C rate, 83% of the original capacity of copper hexacyanoferrate is retained. Even at a very high cycling rate of 83g-C, two thirds of its maximum discharge capacity is observed. At modest current densities, round-trip energy efficiencies of 99% can be achieved. The low-cost, scalable, room-temperature co-precipitation synthesis and excellent electrode performance of copper hexacyanoferrate make it attractive for large-scale energy storage systems. © 2011 Macmillan Publishers Limited. All rights reserved.

Copper hexacyanoferrate battery electrodes with long cycle life and high power

KAUST Repository

Wessells, Colin D.

2011-11-22

Short-term transients, including those related to wind and solar sources, present challenges to the electrical grid. Stationary energy storage systems that can operate for many cycles, at high power, with high round-trip energy efficiency, and at low cost are required. Existing energy storage technologies cannot satisfy these requirements. Here we show that crystalline nanoparticles of copper hexacyanoferrate, which has an ultra-low strain open framework structure, can be operated as a battery electrode in inexpensive aqueous electrolytes. After 40,000 deep discharge cycles at a 17g-C rate, 83% of the original capacity of copper hexacyanoferrate is retained. Even at a very high cycling rate of 83g-C, two thirds of its maximum discharge capacity is observed. At modest current densities, round-trip energy efficiencies of 99% can be achieved. The low-cost, scalable, room-temperature co-precipitation synthesis and excellent electrode performance of copper hexacyanoferrate make it attractive for large-scale energy storage systems. © 2011 Macmillan Publishers Limited. All rights reserved.

In situ transmission electron microscope observation of the formation of fuzzy structures on tungsten

International Nuclear Information System (INIS)

Miyamoto, M; Watanabe, T; Nagashima, H; Nishijima, D; Doerner, R P; Krasheninnikov, S I; Sagara, A; Yoshida, N

2014-01-01

To investigate the formation processes of tungsten nano-structures, so called fuzz, in situ transmission electron microscope observations during helium ion irradiation and high temperature annealing have been performed. The irradiation with 3 keV He + from room temperature to 1273 K is found to cause high-density helium bubbles in tungsten with no significant change in the surface structure. At higher temperatures, surface morphology changes were observed even without helium irradiation due probably to surface diffusion of tungsten atoms driven by surface tension. It is clearly shown that this morphology change is enhanced with helium irradiation, i.e. the formation of helium bubbles. (paper)

High-temperature oxidation of tungsten covered by layer of glass-enamel melt

International Nuclear Information System (INIS)

Vasnetsova, V.B.; Shardakov, N.T.; Kudyakov, V.Ya.; Deryabin, V.A.

1997-01-01

Corrosion losses of tungsten covered by the layer of glass-enamel melt were determined at 800, 850, 900, 950 deg C. It is shown that the rate of high-temperature oxidation of tungsten decreases after application of glass-enamel melt on its surface. This is probably conditioned by reduction of area of metal interaction with oxidizing atmosphere

Optimum tungsten content in high strength 9 to 12% chromium containing creep resistant steels

International Nuclear Information System (INIS)

Hasegawa, Y.; Muraki, T.; Mimura, H.

2000-01-01

Tungsten containing ferritic creep resistant steels are the candidate materials for ultra-super-critical fossil power plant because of their high creep rupture strength. But the strengthening mechanisms by tungsten addition have not yet been completely studied. In this report, creep rupture time and creep strain rate measurement decided the optimum tungsten content in 9 to 12% chromium ferritic steels. The precipitation behavior of Laves phase and the precise discussion of creep strain rate analyses explain the contribution of Laves phase at the lath boundary and the contribution of tungsten in solid solution. P92 contains the optimum amount of tungsten and chromium, 1.8 mass% and 9 mass% respectively judging from the creep rupture strength point of view. (orig.)

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

International Nuclear Information System (INIS)

Strizhko, V.S.; Shekhirev, D.V.; Ignatkina, V.A.; Alimova, R.Eh.

1996-01-01

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

Freeze-dried processing of tungsten heavy alloys

International Nuclear Information System (INIS)

White, G.D.; Gurwell, W.E.

1989-06-01

Tungsten heavy alloy powders were produced from freeze-dried aqueous solutions of ammonium metatungstate and, principally, sulfates of Ni and Fe. The freeze-dried salts were calcined and hydrogen reduced to form very fine, homogeneous, low-density, W heavy alloy powders having a coral-like structure with elements of approximately 0.1 μm in diameter. The powders yield high green strength and sinterability. Tungsten heavy alloy powders of 70%, 90%, and 96% W were prepared by freeze drying, compacted, and solid-state (SS) sintered to fully density at temperatures as low as 1200 degree C and also at conventional liquid-phase (LP) sintering temperatures. Solid-state sintered microstructures contained polygonal W grains with high contiguity; the matrix did not coat and separate the W grains to form low-contiguity, high-ductility structures. Liquid-phase sintered microstructures were very conventional in appearance, having W spheroids of low contiguity. All these materials were found to be brittle. High levels of residual S accompanied by segregation of the S to all the microstructural interfaces are principally responsible for the brittleness; problems with S could be eliminated by using Fe and Ni nitrates rather than the sulfates. 9 refs., 22 figs., 3 tabs

Tungsten and optics

International Nuclear Information System (INIS)

Reglero, V.; Velasco, T.; Rodrigo, J.; Gasent, L.J.; Alamo, J.; Chato, R.; Ruiz Urien, I.; Santos, I.; Zarauz, J.

2001-01-01

High energy astronomy research requires accurate location to perform multiwavelength studies of the cosmic gamma-ray emitters. New technologies have been developed to achieve this goal, the use of large spatial signal multiplexing systems (Masks). The optical system based on the use of coded Masks together with solid stated pixelated planes provide a point source location capability of 1 arc min, that is 3600 times better than of the last NASA CGRO mission. Different materials were considered to modulate the high energy signals, tungsten was selected for implementing the codes due to both its high density and large atomic number that provide the required stooping power. An overview of the programme carried out to design and manufacture the coded Masks is provided. (nevyjel)

First result of deuterium retention in neutron-irradiated tungsten exposed to high flux plasma in TPE

International Nuclear Information System (INIS)

Shimada, Masashi; Hatano, Y.; Calderoni, P.; Oda, T.; Oya, Y.; Sokolov, M.; Zhang, K.; Cao, G.; Kolasinski, R.; Sharpe, J.P.

2011-01-01

With the Japan-US joint research project Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), an initial set of tungsten samples (99.99% purity, A.L.M.T. Co.) were irradiated by high flux neutrons at 323 K to 0.025 dpa in High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Subsequently, one of the neutron-irradiated tungsten samples was exposed to a high-flux deuterium plasma (ion flux: 5 x 10 21 m -2 s -1 , ion fluence: 4 x 10 25 m -2 ) in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory (INL). The deuterium retention in the neutron-irradiated tungsten was 40% higher in comparison to the unirradiated tungsten. The observed broad desorption spectrum from neutron-irradiated tungsten and associated TMAP modeling of the deuterium release suggest that trapping occurs in the bulk material at more than three different energy sites.

First result of deuterium retention in neutron-irradiated tungsten exposed to high flux plasma in TPE

Science.gov (United States)

Shimada, Masashi; Hatano, Y.; Calderoni, P.; Oda, T.; Oya, Y.; Sokolov, M.; Zhang, K.; Cao, G.; Kolasinski, R.; Sharpe, J. P.

2011-08-01

With the Japan-US joint research project Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), an initial set of tungsten samples (99.99% purity, A.L.M.T. Co.) were irradiated by high flux neutrons at 323 K to 0.025 dpa in High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Subsequently, one of the neutron-irradiated tungsten samples was exposed to a high-flux deuterium plasma (ion flux: 5 × 1021 m-2 s-1, ion fluence: 4 × 1025 m-2) in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory (INL). The deuterium retention in the neutron-irradiated tungsten was 40% higher in comparison to the unirradiated tungsten. The observed broad desorption spectrum from neutron-irradiated tungsten and associated TMAP modeling of the deuterium release suggest that trapping occurs in the bulk material at more than three different energy sites.

High Rate Plastic Deformation and Failure of Tungsten-Sintered Metals

National Research Council Canada - National Science Library

Bjerke, Todd

2004-01-01

The competition between plastic deformation and brittle fracture during high rate loading of a tungsten-sintered metal is examined through impact experiments, post-experiment microscopy, and numerical simulation...

Performance of tungsten-based materials and components under ITER and DEMO relevant steady-state thermal loads

Energy Technology Data Exchange (ETDEWEB)

Ritz, Guillaume Henri

2011-07-01

In nuclear fusion devices the surfaces directly facing the plasma are irradiated with high energy fluxes. The most intense loads are deposited on the divertor located at the bottom of the plasma chamber, which has to withstand continuous heat loads with a power density of several MW . m{sup -2} as well as transient events. These are much shorter (in the millisecond and sub-millisecond regime) but deposit a higher power densities of a few GW . m{sup -2}. The search for materials that can survive to those severe loading conditions led to the choice of tungsten which possesses advantageous attributes such as a high melting point, high thermal conductivity, low thermal expansion and an acceptable activation rate. These properties made it an attractive and promising candidate as armor material for divertors of future fusion devices such as ITER and DEMO. For the DEMO divertor, conceptual studies on helium-cooled tungsten plasma-facing components were performed. The concept was realized and tested under DEMO specific cyclic thermal loads. The examination of the plasma-facing components by microstructural analyses before and after thermal loading enabled to determine the mechanisms for components failure. Among others, it clearly showed the impact of the tungsten grade and the thermal stress induced crack formation on the performance of the armor material and in general of the plasma-facing component under high heat loads. A tungsten qualification program was launched to study the behaviour of various tungsten grades, in particular the crack formation, under fusion relevant steady-state thermal loads. In total, seven commercially available materials from two industrial suppliers were investigated. As the material's thermal response is strongly related to its microstructure, this program comprised different material geometries and manufacturing technologies. It also included the utilization of an actively cooled specimen holder which has been designed to perform

Performance of tungsten-based materials and components under ITER and DEMO relevant steady-state thermal loads

International Nuclear Information System (INIS)

Ritz, Guillaume Henri

2011-01-01

In nuclear fusion devices the surfaces directly facing the plasma are irradiated with high energy fluxes. The most intense loads are deposited on the divertor located at the bottom of the plasma chamber, which has to withstand continuous heat loads with a power density of several MW . m -2 as well as transient events. These are much shorter (in the millisecond and sub-millisecond regime) but deposit a higher power densities of a few GW . m -2 . The search for materials that can survive to those severe loading conditions led to the choice of tungsten which possesses advantageous attributes such as a high melting point, high thermal conductivity, low thermal expansion and an acceptable activation rate. These properties made it an attractive and promising candidate as armor material for divertors of future fusion devices such as ITER and DEMO. For the DEMO divertor, conceptual studies on helium-cooled tungsten plasma-facing components were performed. The concept was realized and tested under DEMO specific cyclic thermal loads. The examination of the plasma-facing components by microstructural analyses before and after thermal loading enabled to determine the mechanisms for components failure. Among others, it clearly showed the impact of the tungsten grade and the thermal stress induced crack formation on the performance of the armor material and in general of the plasma-facing component under high heat loads. A tungsten qualification program was launched to study the behaviour of various tungsten grades, in particular the crack formation, under fusion relevant steady-state thermal loads. In total, seven commercially available materials from two industrial suppliers were investigated. As the material's thermal response is strongly related to its microstructure, this program comprised different material geometries and manufacturing technologies. It also included the utilization of an actively cooled specimen holder which has been designed to perform sophisticated

First result of deuterium retention in neutron-irradiated tungsten exposed to high flux plasma in TPE

Energy Technology Data Exchange (ETDEWEB)

Shimada, Masashi, E-mail: Masashi.Shimada@inl.gov [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Hatano, Y. [Hydrogen Isotope Research Center, University of Toyama, Toyama 930-8555 (Japan); Calderoni, P. [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Oda, T. [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo 113-8656 (Japan); Oya, Y. [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan); Sokolov, M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhang, K. [Hydrogen Isotope Research Center, University of Toyama, Toyama 930-8555 (Japan); Cao, G. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States); Kolasinski, R. [Hydrogen and Metallurgical Science Department, Sandia National Laboratories, Livermore, CA 94551 (United States); Sharpe, J.P. [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID 83415 (United States)

2011-08-01

With the Japan-US joint research project Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), an initial set of tungsten samples (99.99% purity, A.L.M.T. Co.) were irradiated by high flux neutrons at 323 K to 0.025 dpa in High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Subsequently, one of the neutron-irradiated tungsten samples was exposed to a high-flux deuterium plasma (ion flux: 5 x 10{sup 21} m{sup -2} s{sup -1}, ion fluence: 4 x 10{sup 25} m{sup -2}) in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory (INL). The deuterium retention in the neutron-irradiated tungsten was 40% higher in comparison to the unirradiated tungsten. The observed broad desorption spectrum from neutron-irradiated tungsten and associated TMAP modeling of the deuterium release suggest that trapping occurs in the bulk material at more than three different energy sites.

Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

Science.gov (United States)

Schoop, Julius Malte

force, temperature and surface roughness data is developed and used to study the deformation mechanisms of porous tungsten under different machining conditions. It is found that when hmax = hc, ductile mode machining of otherwise highly brittle porous tungsten is possible. The value of hc is approximately the same as the average ligament size of the 80% density porous tungsten workpiece.

Self-castellation of tungsten monoblock under high heat flux loading and impact of material properties

Directory of Open Access Journals (Sweden)

S. Panayotis

2017-08-01

Full Text Available In the full-tungsten divertor qualification program at ITER Organization, macro-cracks, so called self-castellation were found in a fraction of tungsten monoblocks during cyclic high heat flux loading at 20MW/m2. The number of monoblocks with macro-cracks varied with the tungsten products used as armour material. In order to understand correlation between the macro-crack appearance and W properties, an activity to characterize W monoblock materials was launched at the IO. The outcome highlighted that the higher the recrystallization resistance, the lower the number of cracks detected during high heat flux tests. Thermo-mechanical finite element modelling demonstrated that the maximum surface temperature ranges from 1800 °C to 2200 °C and in this range recrystallization of tungsten occurred. Furthermore, it indicated that loss of strength due to recrystallization is responsible for the development of macro-cracks in the tungsten monoblock.

Fabrication of Copper-Rich Cu-Al Alloy Using the Wire-Arc Additive Manufacturing Process

Science.gov (United States)

Dong, Bosheng; Pan, Zengxi; Shen, Chen; Ma, Yan; Li, Huijun

2017-12-01

An innovative wire-arc additive manufacturing (WAAM) process is used to fabricate Cu-9 at. pct Al on pure copper plates in situ, through separate feeding of pure Cu and Al wires into a molten pool, which is generated by the gas tungsten arc welding (GTAW) process. After overcoming several processing problems, such as opening the deposition molten pool on the extremely high-thermal conductive copper plate and conducting the Al wire into the molten pool with low feed speed, the copper-rich Cu-Al alloy was successfully produced with constant predesigned Al content above the dilution-affected area. Also, in order to homogenize the as-fabricated material and improve the mechanical properties, two further homogenization heat treatments at 1073 K (800 °C) and 1173 K (900 °C) were applied. The material and mechanical properties of as-fabricated and heat-treated samples were compared and analyzed in detail. With increased annealing temperatures, the content of precipitate phases decreased and the samples showed gradual improvements in both strength and ductility with little variation in microstructures. The present research opened a gate for in-situ fabrication of Cu-Al alloy with target chemical composition and full density using the additive manufacturing process.

Separation of copper flotation concentrates into density fractions by means of polytungstate aqueous solution

Directory of Open Access Journals (Sweden)

Luszczkiewicz Andrzej

2016-01-01

Full Text Available Industrial and laboratory flotation copper concentrates were subjected to separation into density fractions by means of heavy liquids in the form of sodium polytungstate aqueous solutions. For two samples, three densities factions were created, however in different density ranges. The density fractions were analyzed to establish the content of copper, lead, silver and organic carbon. The size of particles in both samples was similar (90-95% −0.071 mm. It was found that the lightest density fractions −2.45 and −2.0 g/cm3 still contained sulfide minerals scattered in the organic carbon bearing particles. Removal of the lightest density fraction (−2.0 g/cm3 from the industrial concentrate samples led to considerable reduction of organic carbon (92% and increasing its quality from 13 to 28% Cu. The mineralogical analysis of the heavy liquid separation products showed that most sulfide minerals were evenly dissemination in the heaviest density fractions with the recovery of 95-98%. The lightest density fraction of −2.0 g/cm3, being the richest in organic carbon, contained approximately 3% of unliberated sulfide minerals.

High-temperature brazing for reliable tungsten-CFC joints

International Nuclear Information System (INIS)

Koppitz, Th; Pintsuk, G; Reisgen, U; Remmel, J; Hirai, T; Sievering, R; Rojas, Y; Casalegno, V

2007-01-01

The joining of tungsten and carbon-based materials is demanding due to the incompatibility of their chemical and thermophysical properties. Direct joining is unfeasible by the reason of brittle tungsten carbide formation. High-temperature brazing has been investigated in order to find a suitable brazing filler metal (BFM) which successfully acts as an intermediary between the incompatible properties of the base materials. So far only low Cr-alloyed Cu-based BFMs provide the preferential combination of good wetting action on both materials, tolerable interface reactions, and a precipitation free braze joint. Attempts to implement a higher melting metal (e.g. Pd, Ti, Zr) as a BFM have failed up to now, because the formation of brittle precipitations and pores in the seam were inevitable. But the wide metallurgical complexity of this issue is regarded to offer further joining potential

Liver mitochondrial dysfunction and electron transport chain defect induced by high dietary copper in broilers.

Science.gov (United States)

Yang, Fan; Cao, Huabin; Su, Rongsheng; Guo, Jianying; Li, Chengmei; Pan, Jiaqiang; Tang, Zhaoxin

2017-09-01

Copper is an important trace mineral in the diet of poultry due to its biological activity. However, limited information is available concerning the effects of high copper on mitochondrial dysfunction. In this study, 72 broilers were used to investigate the effects of high dietary copper on liver mitochondrial dysfunction and electron transport chain defect. Birds were fed with different concentrations [11, 110, 220, and 330 mg of copper/kg dry matter (DM)] of copper from tribasic copper chloride (TBCC). The experiment lasted for 60 d. Liver tissues on d 60 were subjected to histopathological observation. Additionally, liver mitochondrial function was recorded on d 12, 36, and 60. Moreover, a site-specific defect in the electron transport chain in liver mitochondria was also identified by using various chemical inhibitors of mitochondrial respiration. The results showed different degrees of degeneration, mitochondrial swelling, and high-density electrons in hepatocytes. In addition, the respiratory control ratio (RCR) and oxidative phosphorylation rate (OPR) in liver mitochondria increased at first and then decreased in high-dose groups. Moreover, hydrogen peroxide (H2O2) generation velocity in treated groups was higher than that in control group, which were magnified by inhibiting electron transport at Complex IV. The results indicated that high dietary copper could decline liver mitochondrial function in broilers. The presence of a site-specific defect at Complex IV in liver mitochondria may be responsible for liver mitochondrial dysfunction caused by high dietary copper. © 2017 Poultry Science Association Inc.

Deuterium inventory in tungsten after plasma exposure. A microstructural survey

International Nuclear Information System (INIS)

Manhard, Armin

2012-09-01

Tungsten is a promising material for armouring the plasma-facing wall of future nuclear fusion experiments and power plants. It has a very high melting point, good thermal conductivity and is highly resistant against physical sputtering by energetic particles from the plasma. It also has a very low solubility for hydrogen isotopes. This is important both for safety and also for economic reasons, in particular with regard to the radioactive fusion fuel tritium. Due to this low solubility, the retention of hydrogen isotopes in tungsten materials after exposure to a plasma is dominated by the trapping of hydrogen isotopes at tungsten lattice defects. Therefore, a strong dependence of the hydrogen isotope retention on the microstructure of the tungsten is to be expected. This work describes a survey study of tungsten with different microstructures exposed to deuterium plasmas under a wide range of different plasma exposure conditions. The isotope deuterium was used because its natural abundance is much smaller than that of hydrogen (i.e., 1 H). This allows detecting even very small amounts retained in the tungsten practically without background signal. Furthermore, the use of deuterium allows utilising the nuclear reaction 2 D( 3 He,p) 4 He for depth-resolved quantification of the deuterium inventory up to depths of several microns. In order to standardise the specimens as far as possible, they were all cut from the same initial material from a single manufacturing batch. After a chemo-mechanical polishing procedure, which produces a well-defined surface, the specimens were annealed at either of four different temperatures in order to modify the grain structure and the dislocation density. These were then characterised by scanning electron microscopy and scanning transmission electron microscopy. The specimens were subsequently exposed in a fully characterised deuterium plasma source at different specimen temperatures, ion energies and deuterium fluences. In addition

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.

Etching of Copper Coated Mylar Tubes With CF-4 Gas

International Nuclear Information System (INIS)

Ecklund, Karl M.; Hartman, Keith W.; Hebert, Michael J.; Wojcicki, Stanley G.

1996-01-01

Using 5 mm diameter copper coated mylar straw tubes at a potential of 2.30 KV relative to a concentric 20 (mu)m diameter gold-plated tungsten anode, it has been observed that with very low flow rates of CF4-based gases the conductive copper cathode material may be removed entirely from the mylar surface

Preparation of tungsten coatings on graphite by electro-deposition via Na2WO4–WO3 molten salt system

International Nuclear Information System (INIS)

Sun, Ning-bo; Zhang, Ying-chun; Jiang, Fan; Lang, Shao-ting; Xia, Min

2014-01-01

Highlights: • Tungsten coatings on graphite were firstly obtained by electro-deposition method via Na 2 WO 4 –WO 3 molten salt system. • Uniform and dense tungsten coatings could be easily prepared in each face of the sample, especially the complex components. • The obtained tungsten coatings are with high purity, ultra-low oxygen content (about 0.022 wt%). • Modulate pulse parameters can get tungsten coatings with different thickness and hardness. - Abstract: Tungsten coating on graphite substrate is one of the most promising candidate materials as the ITER plasma facing components. In this paper, tungsten coatings on graphite substrates were fabricated by electro-deposition from Na 2 WO 4 –WO 3 molten salt system at 1173 K in atmosphere. Tungsten coatings with no impurities were successfully deposited on graphite substrates under various pulsed current densities in an hour. By increasing the current density from 60 mA cm −2 to 120 mA cm −2 an increase of the average size of tungsten grains, the thickness and the hardness of tungsten coatings occurs. The average size of tungsten grains can reach 7.13 μm, the thickness of tungsten coating was in the range of 28.8–51 μm, and the hardness of coating was higher than 400 HV. No cracks or voids were observed between tungsten coating and graphite substrate. The oxygen content of tungsten coating is about 0.022 wt%

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).

Evaluation of eye shields made of tungsten and aluminum in high-energy electron beams

International Nuclear Information System (INIS)

Weaver, Randi D.; Gerbi, Bruce J.; Dusenbery, Kathryn E.

1998-01-01

3 mm beyond the shield was .048 Gy for the 2-mm shield and .029 Gy for the 3-mm shield (40% decrease). Backscatter was not further decreased using thicker tungsten. With a 6-MeV beam, using the 2-mm or 3-mm custom tungsten eye shields plus 0.5 mm of aluminum, the backscattered doses were 1.03 and 1.02 Gy, respectively. The backscatter dose with 9 MeV was 1.06 Gy using the 2-mm custom shield plus 0.5 mm aluminum and 1.05 Gy with a 3-mm custom shield plus 0.5 mm aluminum. There was very little difference in backscatter dosage under the eyelid using 0.5 vs. 1.0 mm of aluminum. Therefore, for patient comfort, we recommend using 0.5 mm of aluminum. Conclusions: Tungsten is superior to lead as a material for eye shields due to its higher density and lower atomic number (Z). Using 6- and 9-MeV electrons, tungsten provides the necessary protection for the lens and cornea of the eye and decreases the amount of backscatter to the eyelid above the shield

Deuterium trapping in tungsten deposition layers formed by deuterium plasma sputtering

International Nuclear Information System (INIS)

Alimov, V.Kh.; Roth, J.; Shu, W.M.; Komarov, D.A.; Isobe, K.; Yamanishi, T.

2010-01-01

A study of the influence of the deposition conditions on the surface morphology and deuterium (D) concentration in tungsten (W) deposition layers formed by magnetron sputtering and in the linear plasma generator has been carried out. Thick W layers (≥0.4 μm) deposited onto copper substrates demonstrate areas of pilling and, after post-deposition heating to 1300 K, flaking-off and fracturing. For thin W layers (≤80 nm) deposited onto stainless steel (SS) and W substrates, no areas of flaking-off and fracturing exist both after deposition and after post-deposition heating to 673 K for the SS substrate and to 1300 K for the W substrate. The concentration of deuterium in the W layers was found to decrease with increasing substrate temperature and with increasing tungsten deposition rate. For layers with relatively high concentration of oxygen (0.20-0.60 O/W), a decrease of the D concentration with increasing substrate temperature is more pronounced than that for layers deposited in good vacuum conditions. To describe the evolution of the D/W ratio with the substrate temperature and the tungsten deposition rate, an empirical equation proposed by De Temmerman and Doerner [J. Nucl. Mater. 389 (2009) 479] but with alternative parameters has been used.

Methods of analytical check for highly pure tungsten

International Nuclear Information System (INIS)

Miklin, D.G.; Karpov, Yu.A.; Orlova, V.A.

1993-01-01

The review is devoted to the methods of high-purity tungsten analysis. Current trends in the development of this branch of analytical chemistry are considered. Application of both instrument mass-spectrometry analysis and optico-spectral, activation methods and mass-spectrometry ones with inductively-bound plasma in combination with preliminary isolation of the basis and impurity concentration is expected to be the most actual

Hydrogen Release From 800-MeV Proton-Irradiated Tungsten

International Nuclear Information System (INIS)

Oliver, Brian M.; Venhaus, Thomas J.; Causey, Rion A.; Garner, Francis A.; Maloy, Stuart A.

2002-01-01

Tungsten irradiated in spallation neutron sources such as those proposed for the Accelerator Production of Tritium (APT) project, or in proposed fusion reactors, will contain large quantities of generated helium and hydrogen gas. In the APT, spallation neutrons would be generated by the interaction of high energy (∼1 GeV) protons with solid tungsten rods or cylinders. In fusion reactors, tungsten used in a tokamak diverter will contain hydrogen, as well as deuterium and tritium diffusing in from the plasma-facing surface. The release kinetics of these gases during various off-normal scenarios involving loss of coolant and afterheat-induced rises in temperature is of particular interest for both applications. To determine the release kinetics of hydrogen from tungsten, tungsten rods irradiated with 800 MeV protons in the Los Alamos Neutron Science Center (LANCE) to high exposures as part of the APT project have been examined. Hydrogen evolution from the tungsten was measured using a dedicated mass spectrometer system by subjecting the specimens to an essentially linear temperature ramp from ∼323 K to ∼1473 K. Release profiles are compared with predictions obtained using the Tritium Migration Analysis Program (TMAP4). Input parameters for the modeling, consisting of diffusivity, recombination rate coefficient, and trapping, are discussed. The measurements show that for high proton doses, the majority of the hydrogen is released gradually, starting at about 900 K and reaching a maximum at about 1400 K, where it drops fairly rapidly. Comparisons with TMAP show reasonable agreement at high proton dose using a trap value of 1.4 eV and a trap density of 3%. There is also a small release fraction occurring at ∼600 K which predominates at lower proton doses, and which is relatively independent of dose. This lower-temperature release is predicted by TMAP if no traps are assumed, suggesting that this release may represent an adsorbed surface component

Self-castellation of tungsten monoblock under high heat flux loading and impact of material properties

OpenAIRE

Panayotis, S.; Hirai, T.; Wirtz, Marius; Barabash, V.; Durocher, A.; Escourbiac, F.; Linke, J.; Loewenhoff, Th.; Merola, M.; Pintsuk, G.; Uytdenhouwen, I.

2017-01-01

In the full-tungsten divertor qualification program at ITER Organization, macro-cracks, so called self-castellation were found in a fraction of tungsten monoblocks during cyclic high heat flux loading at 20MW/m2. The number of monoblocks with macro-cracks varied with the tungsten products used as armour material. In order to understand correlation between the macro-crack appearance and W properties, an activity to characterize W monoblock materials was launched at the IO. The outcome highligh...

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)

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)

Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

Directory of Open Access Journals (Sweden)

Zhongwen Wu

2015-11-01

Full Text Available Electron impact excitation (EIE and dielectronic recombination (DR of tungsten ions are basic atomic processes in nuclear fusion plasmas of the International Thermonuclear Experimental Reactor (ITER tokamak. Detailed investigation of such processes is essential for modeling and diagnosing future fusion experiments performed on the ITER. In the present work, we studied total and partial electron-impact excitation (EIE and DR cross-sections of highly charged tungsten ions by using the multiconfiguration Dirac–Fock method. The degrees of linear polarization of the subsequent X-ray emissions from unequally-populated magnetic sub-levels of these ions were estimated. It is found that the degrees of linear polarization of the same transition lines, but populated respectively by the EIE and DR processes, are very different, which makes diagnosis of the formation mechanism of X-ray emissions possible. In addition, with the help of the flexible atomic code on the basis of the relativistic configuration interaction method, DR rate coefficients of highly charged W37+ to W46+ ions are also studied, because of the importance in the ionization equilibrium of tungsten plasmas under running conditions of the ITER.

Mechanical properties and microstructure of copper alloys and copper alloy-stainless steel laminates for fusion reactor high heat flux applications

Science.gov (United States)

Leedy, Kevin Daniel

A select group of copper alloys and bonded copper alloy-stainless steel panels are under consideration for heat sink applications in first wall and divertor structures of a planned thermonuclear fusion reactor. Because these materials must retain high strengths and withstand high heat fluxes, their material properties and microstructures must be well understood. Candidate copper alloys include precipitate strengthened CuNiBe and CuCrZr and dispersion strengthened Cu-Alsb2Osb3 (CuAl25). In this study, uniaxial mechanical fatigue tests were conducted on bulk copper alloy materials at temperatures up to 500sp°C in air and vacuum environments. Based on standardized mechanical properties measurement techniques, a series of tests were also implemented to characterize copper alloy-316L stainless steel joints produced by hot isostatic pressing or by explosive bonding. The correlation between mechanical properties and the microstructure of fatigued copper alloys and the interface of copper alloy-stainless steel laminates was examined. Commercial grades of these alloys were used to maintain a degree of standardization in the materials testing. The commercial alloys used were OMG Americas Glidcop CuAl25 and CuAl15; Brush Wellman Hycon 3HP and Trefimetaux CuNiBe; and Kabelmetal Elbrodur and Trefimetaux CuCrZr. CuAl25 and CuNiBe alloys possessed the best combination of fatigue resistance and microstructural stability. The CuAl25 alloy showed only minimal microstructural changes following fatigue while the CuNiBe alloy consistently exhibited the highest fatigue strength. Transmission electron microscopy observations revealed that small matrix grain sizes and high densities of submicron strengthening phases promoted homogeneous slip deformation in the copper alloys. Thus, highly organized fatigue dislocation structure formation, as commonly found in oxygen-free high conductivity Cu, was inhibited. A solid plate of CuAl25 alloy hot isostatically pressed to a 316L stainless steel

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

A study of tungsten spectra using large helical device and compact electron beam ion trap in NIFS

Science.gov (United States)

Morita, S.; Dong, C. F.; Goto, M.; Kato, D.; Murakami, I.; Sakaue, H. A.; Hasuo, M.; Koike, F.; Nakamura, N.; Oishi, T.; Sasaki, A.; Wang, E. H.

2013-07-01

Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The EUV spectra with unresolved transition array (UTA), e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W+24-+33, measured from LHD plasmas are compared with those measured from CoBIT with monoenergetic electron beam (≤2keV). The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. As the first trial, analysis of the tungsten density in LHD plasmas is attempted from radial profile of Zn-like WXLV (W44+) 4p-4s transition at 60.9Å based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5×1010cm-3 at the plasma center is reasonably obtained. In order to observe the spectra from tungsten ions in lower-ionized charge stages, which can give useful information on the tungsten influx in fusion plasmas, the ablation cloud of the impurity pellet is directly measured with visible spectroscopy. A lot of spectra from neutral and singly ionized tungsten are observed and some of them are identified. A magnetic forbidden line from highly ionized tungsten ions has been examined and Cd-like WXXVII (W26+) at 3893.7Å is identified as the ground-term fine-structure transition of 4f23H5-3H4. The possibility of α particle diagnostic in D-T burning plasmas using the magnetic forbidden line is discussed.

A study of tungsten spectra using large helical device and compact electron beam ion trap in NIFS

International Nuclear Information System (INIS)

Morita, S.; Goto, M.; Murakami, I.; Dong, C. F.; Kato, D.; Sakaue, H. A.; Oishi, T.; Hasuo, M.; Koike, F.; Nakamura, N.; Sasaki, A.; Wang, E. H.

2013-01-01

Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The EUV spectra with unresolved transition array (UTA), e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W +24-+33 , measured from LHD plasmas are compared with those measured from CoBIT with monoenergetic electron beam (≤2keV). The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. As the first trial, analysis of the tungsten density in LHD plasmas is attempted from radial profile of Zn-like WXLV (W 44+ ) 4p-4s transition at 60.9Å based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5×10 10 cm −3 at the plasma center is reasonably obtained. In order to observe the spectra from tungsten ions in lower-ionized charge stages, which can give useful information on the tungsten influx in fusion plasmas, the ablation cloud of the impurity pellet is directly measured with visible spectroscopy. A lot of spectra from neutral and singly ionized tungsten are observed and some of them are identified. A magnetic forbidden line from highly ionized tungsten ions has been examined and Cd-like WXXVII (W 26+ ) at 3893.7Å is identified as the ground-term fine-structure transition of 4f 23 H 5 - 3 H 4 . The possibility of α particle diagnostic in D-T burning plasmas using the magnetic forbidden line is discussed

A study of tungsten spectra using large helical device and compact electron beam ion trap in NIFS

Energy Technology Data Exchange (ETDEWEB)

Morita, S.; Goto, M.; Murakami, I. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Dong, C. F.; Kato, D.; Sakaue, H. A.; Oishi, T. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Hasuo, M. [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan); Koike, F. [Physics Laboratory, School of Medicine, Kitasato University, Sagamihara 252-0374 (Japan); Nakamura, N. [Institute of Laser Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Sasaki, A. [Quantum Beam Science Directorate, Japan Atomic Energy Research Agency, Kizugawa 619-0215, Kyoto (Japan); Wang, E. H. [Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan)

2013-07-11

Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The EUV spectra with unresolved transition array (UTA), e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W{sup +24-+33}, measured from LHD plasmas are compared with those measured from CoBIT with monoenergetic electron beam ({<=}2keV). The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. As the first trial, analysis of the tungsten density in LHD plasmas is attempted from radial profile of Zn-like WXLV (W{sup 44+}) 4p-4s transition at 60.9A based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5 Multiplication-Sign 10{sup 10}cm{sup -3} at the plasma center is reasonably obtained. In order to observe the spectra from tungsten ions in lower-ionized charge stages, which can give useful information on the tungsten influx in fusion plasmas, the ablation cloud of the impurity pellet is directly measured with visible spectroscopy. A lot of spectra from neutral and singly ionized tungsten are observed and some of them are identified. A magnetic forbidden line from highly ionized tungsten ions has been examined and Cd-like WXXVII (W{sup 26+}) at 3893.7A is identified as the ground-term fine-structure transition of 4f{sup 23}H{sub 5}-{sup 3}H{sub 4}. The possibility of {alpha} particle diagnostic in D-T burning plasmas using the magnetic forbidden line is discussed.

MRR and TWR evaluation on electrical discharge machining of Ti-6Al-4V using tungsten : copper composite electrode

Science.gov (United States)

Prasanna, J.; Rajamanickam, S.; Amith Kumar, O.; Karthick Raj, G.; Sathya Narayanan, P. V. V.

2017-05-01

In this paper Ti-6Al-4V used as workpiece material and it is keenly seen in variety of field including medical, chemical, marine, automotive, aerospace, aviation, electronic industries, nuclear reactor, consumer products etc., The conventional machining of Ti-6Al-4V is very difficult due to its distinctive properties. The Electrical Discharge Machining (EDM) is right choice of machining this material. The tungsten copper composite material is employed as tool material. The gap voltage, peak current, pulse on time and duty factor is considered as the machining parameter to analyze the machining characteristics Material Removal Rate (MRR) and Tool Wear Rate (TWR). The Taguchi method is provided to work for finding the significant parameter of EDM. It is found that for MRR significant parameters rated in the following order Gap Voltage, Pulse On-Time, Peak Current and Duty Factor. On the other hand for TWR significant parameters are listed in line of Gap Voltage, Duty Factor, Peak Current and Pulse On-Time.

Experimental and numerical simulations of ELM-like transient damage behaviors to different grade tungsten and tungsten alloys

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiang, E-mail: xliu@swip.ac.cn [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Lian, Youyun; Chen, Lei; Chen, Zhenkui; Chen, Jiming; Duan, Xuru [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Fan, Jinlian [Central South University, Changsha 410083 (China); Song, Jiupeng [Xiamen Honglu Tungsten & Molybdenum Industry Co., Ltd, Xiamen (China)

2015-08-15

Transient heat loads, such as plasma disruptions and ELMs, could induce plastic deformations, cracking, melting, even fatigue cracks and creep of tungsten (W) surface. A high purity W, CVD-W coating, TiC dispersion strengthened and K doped tungsten alloys were tested in a 60 kW electron-beam facility by simulating the transient load events under different base temperatures. It was found that CVD-W, W-TiC and W-K alloys have higher crack thresholds than high purity W, meanwhile CVD-W is more sensitive to the crack disappearing at elevated base temperatures. On the other hand, repetitive pulse loading like ELMs can induce serious network cracks even the power density was quite lower than the crack threshold determined by a single shot. The ABAQUS code was used to simulate the crack behaviors of ITER grade pure W by a single shot and a FE-SAFE code was adopted to estimate the fatigue life under ELMs-like loads. A good agreement with experiment results was found.

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

Solid-state sintering of tungsten heavy alloys

International Nuclear Information System (INIS)

Gurwell, W.E.

1994-10-01

Solid-state sintering is a technologically important step in the fabrication of tungsten heavy alloys. This work addresses practical variables affecting the sinterability: powder particle size, powder mixing, and sintering temperature and time. Compositions containing 1 to 10 micrometer (μM) tungsten (W) powders can be fully densified at temperatures near the matrix solidus. Blending with an intensifier bar provided good dispersion of elemental powders and good as-sintered mechanical properties under adequate sintering conditions. Additional ball milling increases powder bulk density which primarily benefits mold and die filling. Although fine, 1 μm W powder blends have high sinterability, higher as-sintered ductilities are reached in shorter sintering times with coarser, 5 μm W powder blends; 10μm W powder blends promise the highest as-sintered ductilities due to their coarse microstructural W

Die casting copper motor rotors: mold materials and processing for cost-effective manufacturing

Energy Technology Data Exchange (ETDEWEB)

Peters, D.T.; Cowie, J.G.; Brush, E.F. Jr.

2000-07-01

This project seeks to demonstrate mold materials for copper pressure die-casting that are cost-effective and practical for production use in die-casting copper motor rotors. The incorporation of die-cast copper for conductor bars and end rings of the induction motor in place of aluminum would result in attractive improvements in motor energy efficiency through reductions in motor losses ranging from 15% to 20%. Die-cast motor rotors are produced in aluminum today because rotor fabrication by pressure die-casting is an established practice. Lack of a durable and cost-effective mold material has been the technical barrier preventing manufacture of the die-cast copper rotor. This project tested H-13 steel die inserts that establish the baseline. Nickel-, tungsten-, and molybdenum-based high temperature alloys were extensively tested. Results indicate that substantially extended die life is possible using high temperature die materials, pre-heated and operated at elevated temperatures. Pre-heating and high operating temperatures were shown to be critical in extending the die life by decreasing the cyclic stresses associated with thermal expansion. Extended die life provides the opportunity for economically viable copper motor rotor die-casting. (orig.)

Radiation damage in molybdenum and tungsten in high neutron fluxes

International Nuclear Information System (INIS)

Veljkovic, S.; Milasin, N.

1964-01-01

The effects of radiation on molybdenum and tungsten in high neutron fluxes are presented. The changes induced, particularly defects with a high migration activation energy, are analyzed. The correlation of these changes with the basic concepts of radiation damage in solids is considered. An attempt is made to relate the defects studied with the changes in macroscopic properties (author)

Radiation damage in molybdenum and tungsten in high neutron fluxes

Energy Technology Data Exchange (ETDEWEB)

Veljkovic, S; Milasin, N [Institute of Nuclear Sciences Boris Kidric, Department of Reactor Materials, Vinca, Beograd (Serbia and Montenegro)

1964-04-15

The effects of radiation on molybdenum and tungsten in high neutron fluxes are presented. The changes induced, particularly defects with a high migration activation energy, are analyzed. The correlation of these changes with the basic concepts of radiation damage in solids is considered. An attempt is made to relate the defects studied with the changes in macroscopic properties (author)

Simulation of cracks in tungsten under ITER specific heat loads

International Nuclear Information System (INIS)

Peschany, S.

2006-01-01

withstand high heat flux. Fusion Engineering and Design v. 81/1-7 pp. 275-279] has been applied. Originally the code has been developed for simulation of brittle destruction in CFC and graphites. It has been tested against plasma gun experiments and proved reliability of its predictions. Now it has been modified to simulate crack formation in tungsten using a model for crack generation in the resolidified surface layer and propagation of cracks in the bulk. The model assumes that initially the resolidified layer is stress-less at the melting temperature and then the tensile stress develops in the layer during its cooling down. First results of the simulations are reported. The simulations reproduce tungsten crack morphology and predict the crack densities and the cracks depth. (author)

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)

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

Evaluation of the feasibility of joining titanium alloy to heavymet tungsten alloy

Energy Technology Data Exchange (ETDEWEB)

1978-06-07

Information is presented on a program to select and evaluate methods of brazing and/or explosively welding Ti-6Al-4V titanium alloy to Heavymet, a tungsten-base metal containing up to about 20% alloying elements (nickel, copper, etc.) to improve its ductility and other mechanical properties. Designs permitting the reliable production of joints between these base metals were of interest too. While this investigation was primarily concerned with an engineering study of the problems associated with joining these base metals in the required configuration, limited experimental studies were conducted also. The joining methods are reviewed individually. Recommendations for developing a viable titanium-tungsten joining procedure are discussed.

Evaluation of the feasibility of joining titanium alloy to heavymet tungsten alloy

International Nuclear Information System (INIS)

1978-01-01

Information is presented on a program to select and evaluate methods of brazing and/or explosively welding Ti-6Al-4V titanium alloy to Heavymet, a tungsten-base metal containing up to about 20% alloying elements (nickel, copper, etc.) to improve its ductility and other mechanical properties. Designs permitting the reliable production of joints between these base metals were of interest too. While this investigation was primarily concerned with an engineering study of the problems associated with joining these base metals in the required configuration, limited experimental studies were conducted also. The joining methods are reviewed individually. Recommendations for developing a viable titanium-tungsten joining procedure are discussed

Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

International Nuclear Information System (INIS)

Altamore, C; Tringali, C; Sparta', N; Marco, S Di; Grasso, A; Ravesi, S

2010-01-01

In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (10 5 ) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 10 1 Hz to 10 6 Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl 2 /Ar chemistry. The relationship between the etch rate and the Cl 2 /Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl 2 /Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

Energy Technology Data Exchange (ETDEWEB)

Altamore, C; Tringali, C; Sparta' , N; Marco, S Di; Grasso, A; Ravesi, S [STMicroelectronics, Industial and Multi-segment Sector R and D, Catania (Italy)

2010-02-15

In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (10{sup 5}) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 10{sup 1} Hz to 10{sup 6} Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl{sub 2}/Ar chemistry. The relationship between the etch rate and the Cl{sub 2}/Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl{sub 2}/Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

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

Hydrogen release from 800 MeV proton-irradiated tungsten

Science.gov (United States)

Oliver, B. M.; Venhaus, T. J.; Causey, R. A.; Garner, F. A.; Maloy, S. A.

2002-12-01

Tungsten irradiated in spallation neutron sources, such as those proposed for the accelerator production of tritium (APT) project, will contain large quantities of generated helium and hydrogen gas. Tungsten used in proposed fusion reactors will also be exposed to neutrons, and the generated protium will be accompanied by deuterium and tritium diffusing in from the plasma-facing surface. The release kinetics of these gases during various off-normal scenarios involving loss of coolant and after heat-induced rises in temperature are of particular interest for both applications. To determine the release kinetics of hydrogen from tungsten, tungsten rods irradiated with 800 MeV protons in the Los Alamos Neutron Science Center (LANSCE) to high exposures as part of the APT project have been examined. Hydrogen evolution from the tungsten has been measured using a dedicated mass-spectrometer system by subjecting the specimens to an essentially linear temperature ramp from ˜300 to ˜1500 K. Release profiles are compared with predictions obtained using the Tritium Migration Analysis Program (TMAP4). The measurements show that for high proton doses, the majority of the hydrogen is released gradually, starting at about 900 K and reaching a maximum at about 1400 K, where it drops fairly rapidly. Comparisons with TMAP show quite reasonable agreement using a trap energy of 1.4 eV and a trap density of ˜7%. There is a small additional release fraction occurring at ˜550 K, which is believed to be associated with low-energy trapping at or near the surface, and, therefore, was not included in the bulk TMAP model.

Hydrogen release from 800 MeV proton-irradiated tungsten

International Nuclear Information System (INIS)

Oliver, B.M.; Venhaus, T.J.; Causey, R.A.; Garner, F.A.; Maloy, S.A.

2002-01-01

Tungsten irradiated in spallation neutron sources, such as those proposed for the accelerator production of tritium (APT) project, will contain large quantities of generated helium and hydrogen gas. Tungsten used in proposed fusion reactors will also be exposed to neutrons, and the generated protium will be accompanied by deuterium and tritium diffusing in from the plasma-facing surface. The release kinetics of these gases during various off-normal scenarios involving loss of coolant and after heat-induced rises in temperature are of particular interest for both applications. To determine the release kinetics of hydrogen from tungsten, tungsten rods irradiated with 800 MeV protons in the Los Alamos Neutron Science Center (LANSCE) to high exposures as part of the APT project have been examined. Hydrogen evolution from the tungsten has been measured using a dedicated mass-spectrometer system by subjecting the specimens to an essentially linear temperature ramp from ∼300 to ∼1500 K. Release profiles are compared with predictions obtained using the Tritium Migration Analysis Program (TMAP4). The measurements show that for high proton doses, the majority of the hydrogen is released gradually, starting at about 900 K and reaching a maximum at about 1400 K, where it drops fairly rapidly. Comparisons with TMAP show quite reasonable agreement using a trap energy of 1.4 eV and a trap density of ∼7%. There is a small additional release fraction occurring at ∼550 K, which is believed to be associated with low-energy trapping at or near the surface, and, therefore, was not included in the bulk TMAP model

Hydrogen release from 800 MeV proton-irradiated tungsten

Energy Technology Data Exchange (ETDEWEB)

Oliver, B.M. E-mail: brian.oliver@pnl.gov; Venhaus, T.J.; Causey, R.A.; Garner, F.A.; Maloy, S.A

2002-12-01

Tungsten irradiated in spallation neutron sources, such as those proposed for the accelerator production of tritium (APT) project, will contain large quantities of generated helium and hydrogen gas. Tungsten used in proposed fusion reactors will also be exposed to neutrons, and the generated protium will be accompanied by deuterium and tritium diffusing in from the plasma-facing surface. The release kinetics of these gases during various off-normal scenarios involving loss of coolant and after heat-induced rises in temperature are of particular interest for both applications. To determine the release kinetics of hydrogen from tungsten, tungsten rods irradiated with 800 MeV protons in the Los Alamos Neutron Science Center (LANSCE) to high exposures as part of the APT project have been examined. Hydrogen evolution from the tungsten has been measured using a dedicated mass-spectrometer system by subjecting the specimens to an essentially linear temperature ramp from {approx}300 to {approx}1500 K. Release profiles are compared with predictions obtained using the Tritium Migration Analysis Program (TMAP4). The measurements show that for high proton doses, the majority of the hydrogen is released gradually, starting at about 900 K and reaching a maximum at about 1400 K, where it drops fairly rapidly. Comparisons with TMAP show quite reasonable agreement using a trap energy of 1.4 eV and a trap density of {approx}7%. There is a small additional release fraction occurring at {approx}550 K, which is believed to be associated with low-energy trapping at or near the surface, and, therefore, was not included in the bulk TMAP model.

Development of bonding techniques between tungsten and copper alloy for plasma facing components by HIP method (2). Bonding between tungsten and DS-copper

International Nuclear Information System (INIS)

Saito, Shigeru; Fukaya, Kiyoshi; Eto, Motokuni; Ishiyama, Shintaro; Akiba, Masato

2000-02-01

Recently, W (tungsten)-alloys are considered as plasma facing material (PFM) for ITER because of these many favorable properties such as high melting point (3655 K), relatively high thermal conductivity and higher resistivity for plasma sputtering. On the other hand, Cu-alloys, especially DS (dispersion strengthened)-Cu, are proposed as heat sink materials because of its high thermal conductivity and good mechanical properties at high temperature. Plasma facing components (PFC) are designed as the duplex structure where W armor tiles are bonded with Cu-alloy heat sink. Then, we started the bonding technology development by hot isostatic press (HIP) method to bond W with Cu-alloys because of its many advantages. Until now, it was reported that we could get the best HIP bonding conditions for W and OFHC-Cu and the tensile strength was similar with HIP treated OFHC-Cu. In this experiments, bonding tests of W and DS-Cu with insert material were performed. As insert material, OFHC-Cu was used with different thickness. Bonding conditions were selected as 1273 K x 2 hours x 147 MPa. Bonding tests with 0.3 to 1.8 mm thickness OFHC-Cu were successfully bonded but with 0.1 mm thickness was not bonded. From the results of tensile tests, the tensile strength of the specimens with 0.3 and 0.5 mm thickness were decreased at elevated temperature. It was shown that over 1.0 mm thickness OFHC-Cu insert may be needed and the tensile strength were a little higher than that of HIP treated OFHC-Cu. (author)

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

Directory of Open Access Journals (Sweden)

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.

Demonstration of production of tungsten metal powder and its consolidation into shapes

International Nuclear Information System (INIS)

Majumdar, S.; Kishor, J.; Paul, B.; Kain, V.; Dey, G.K.

2016-01-01

Tungsten is a strategically important metal used as plasma facing component in fusion reactors, radiation shields in cancer therapy machines, ammunition in defence applications, high speed cutting tools etc. The primary resources or minerals occurring in India contain a very low value (0.25-0.5 wt. %) of tungsten. Mineral beneficiation processes involving crushing, grinding, primary and secondary gravity separation, floatation are essential to produce the ore-concentrate suitable for further processing up to the preparation of the intermediate ammonium para-tungstate (APT). APT was further converted to tungsten tri-oxide (WO_3). Hydrogen reduction of WO_3 producing high purity W metal powder was demonstrated in large scale batches. Densification of W powder was further studied using vacuum hot pressing at 1950°C, and high density W metal plates of 5 mm thickness and 60 mm diameter were produced. The products obtained at every stage were systematically characterized using X-Ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD) techniques. (author)

Testing hadronic interaction models using a highly granular silicon-tungsten calorimeter

Czech Academy of Sciences Publication Activity Database

Bilki, B.; Repond, J.; Schlereth, J.; Cvach, Jaroslav; Gallus, Petr; Havránek, Miroslav; Janata, Milan; Kvasnička, Jiří; Lednický, Richard; Marčišovský, Michal; Polák, Ivo; Popule, Jiří; Tomášek, Lukáš; Tomášek, Michal; Růžička, Pavel; Šícho, Petr; Smolík, Jan; Vrba, Václav; Zálešák, Jaroslav

2015-01-01

Roč. 794, Sep (2015), s. 240-254 ISSN 0168-9002 R&D Projects: GA MŠk LG14033 Institutional support: RVO:68378271 Keywords : electromagnetic silicon tungsten calorimeter * highly granular detectors * hadronic showers * data and simulations Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.200, year: 2015

Preparation of tungsten coatings on graphite by electro-deposition via Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system

Energy Technology Data Exchange (ETDEWEB)

Sun, Ning-bo [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Zhang, Ying-chun, E-mail: zycustb@163.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Jiang, Fan; Lang, Shao-ting [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Xia, Min [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Institute of Powder Metallurgy and Advanced Ceramics, Southwest Jiaotong University, 111, 1st Section, Northern 2nd Ring Road, Chengdu (China)

2014-11-15

Highlights: • Tungsten coatings on graphite were firstly obtained by electro-deposition method via Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system. • Uniform and dense tungsten coatings could be easily prepared in each face of the sample, especially the complex components. • The obtained tungsten coatings are with high purity, ultra-low oxygen content (about 0.022 wt%). • Modulate pulse parameters can get tungsten coatings with different thickness and hardness. - Abstract: Tungsten coating on graphite substrate is one of the most promising candidate materials as the ITER plasma facing components. In this paper, tungsten coatings on graphite substrates were fabricated by electro-deposition from Na{sub 2}WO{sub 4}–WO{sub 3} molten salt system at 1173 K in atmosphere. Tungsten coatings with no impurities were successfully deposited on graphite substrates under various pulsed current densities in an hour. By increasing the current density from 60 mA cm{sup −2} to 120 mA cm{sup −2} an increase of the average size of tungsten grains, the thickness and the hardness of tungsten coatings occurs. The average size of tungsten grains can reach 7.13 μm, the thickness of tungsten coating was in the range of 28.8–51 μm, and the hardness of coating was higher than 400 HV. No cracks or voids were observed between tungsten coating and graphite substrate. The oxygen content of tungsten coating is about 0.022 wt%.

Analysis and fabrication of tungsten CERMET materials for ultra-high temperature reactor applications via pulsed electric current sintering

Science.gov (United States)

Webb, Jonathan A.

The optimized development path for the fabrication of ultra-high temperature W-UO2 CERMET fuel elements were explored within this dissertation. A robust literature search was conducted, which concluded that a W-UO 2 fuel element must contain a fine tungsten microstructure and spherical UO2 kernels throughout the entire consolidation process. Combined Monte Carlo and Computational Fluid Dynamics (CFD) analysis were used to determine the effects of rhenium and gadolinia additions on the performance of W-UO 2 fuel elements at refractory temperatures and in dry and water submerged environments. The computational analysis also led to the design of quasi-optimized fuel elements that can meet thermal-hydraulic and neutronic requirements A rigorous set of experiments were conducted to determine if Pulsed Electric Current Sintering (PECS) can fabricate tungsten and W-Ce02 specimens to the required geometries, densities and microstructures required for high temperature fuel elements as well as determine the mechanisms involved within the PECS consolidation process. The CeO2 acts as a surrogate for UO 2 fuel kernels in these experiments. The experiments seemed to confirm that PECS consolidation takes place via diffusional mass transfer methods; however, the densification process is rapidly accelerated due to the effects of current densities within the consolidating specimen. Fortunately the grain growth proceeds at a traditional rate and the PECS process can yield near fully dense W and W-Ce02 specimens with a finer microstructure than other sintering techniques. PECS consolidation techniques were also shown to be capable of producing W-UO2 segments at near-prototypic geometries; however, great care must be taken to coat the fuel particles with tungsten prior to sintering. Also, great care must be taken to ensure that the particles remain spherical in geometry under the influence of a uniaxial stress as applied during PECS, which involves mixing different fuel kernel sizes in

High-pressure synthesis of fully occupied tetragonal and cubic tungsten bronze oxides

Energy Technology Data Exchange (ETDEWEB)

Ikeuchi, Yuya; Takatsu, Hiroshi; Tassel, Cedric; Goto, Yoshihiro; Murakami, Taito; Kageyama, Hiroshi [Graduate School of Engineering, Kyoto University (Japan)

2017-05-15

A high-pressure reaction yielded the fully occupied tetragonal tungsten bronze K{sub 3}W{sub 5}O{sub 15} (K{sub 0.6}WO{sub 3}). The terminal phase shows an unusual transport property featuring slightly negative temperature-dependence in resistivity (dρ/dT<0) and a large Wilson ratio of R{sub W}=3.2. Such anomalous metallic behavior possibly arises from the low-dimensional electronic structure with a van Hove singularity at the Fermi level and/or from enhanced magnetic fluctuations by geometrical frustration of the tungsten sublattice. The asymmetric nature of the tetragonal tungsten bronze K{sub x}WO{sub 3}-K{sub 0.6-y}Ba{sub y}WO{sub 3} phase diagram implies that superconductivity for x≤0.45 originates from the lattice instability because of potassium deficiency. A cubic perovskite KWO{sub 3} phase was also identified as a line phase - in marked contrast to Na{sub x}WO{sub 3} and Li{sub x}WO{sub 3} with varying quantities of x (<1). This study presents a versatile method by which the solubility limit of tungsten bronze oxides can be extended. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

High-speed collision of copper nanoparticle with aluminum surface: Molecular dynamics simulation

Science.gov (United States)

Pogorelko, Victor V.; Mayer, Alexander E.; Krasnikov, Vasiliy S.

2016-12-01

We investigate the effect of the high-speed collision of copper nanoparticles with aluminum surface by means of molecular dynamic simulations. Studied diameter of nanoparticles is varied within the range 7.2-22 nm and the velocity of impact is equal to 500 or 1000 m/s. Dislocation analysis shows that a large quantity of dislocations is formed within the impact area. Overall length of dislocations is determined, first of all, by the impact velocity and by the size of incident copper nanoparticle, in other words, by the kinetic energy of the nanoparticle. Dislocations occupy the total volume of the impacted aluminum single crystal layer (40.5 nm in thickness) in the form of intertwined structure in the case of large kinetic energy of the incident nanoparticle. Decrease in the initial kinetic energy or increase in the layer thickness lead to restriction of the penetration depth of the dislocation net; formation of separate dislocation loops is observed in this case. Increase in the initial system temperature slightly raises the dislocation density inside the bombarded layer and considerably decreases the dislocation density inside the nanoparticle. The temperature increase also leads to a deeper penetration of the copper atoms inside the aluminum. Additional molecular dynamic simulations show that the deposited particles demonstrate a very good adhesion even in the case of the considered relatively large nanoparticles. Medium energy of the nanoparticles corresponding to velocity of about 500 m/s and elevated temperature of the system about 700-900 K are optimal parameters for production of high-quality layers of copper on the aluminum surface. These conditions provide both a good adhesion and a less degree of the plastic deformation. At the same time, higher impact velocities can be used for combined treatment consisting of both the plastic deformation and the coating.

Tribological properties of copper-based composites with copper coated NbSe2 and CNT

International Nuclear Information System (INIS)

Chen, Beibei; Yang, Jin; Zhang, Qing; Huang, Hong; Li, Hongping; Tang, Hua; Li, Changsheng

2015-01-01

Graphical abstract: Morphology of copper coated NbSe 2 and CNT; friction coefficient and wear rate of copper-based composites. - Highlights: • NbSe 2 and CNT were coated with copper layers by the means of electroless plating. • The mechanical and tribological properties of copper composites were studied. • The enhancement mechanisms of copper coated NbSe 2 and CNT were proposed. • Copper–copper coated (12 wt.%NbSe 2 –3 wt.%CNT) composite had the best wear resistance. - Abstract: Copper-based composites with copper coated NbSe 2 and/or CNT were fabricated by the powder metallurgy technique. The morphology and phase composition of copper coated NbSe 2 and carbon nanotube (CNT) were observed using high solution transmission electronic microscope (HRTEM), scanning electronic microscope (SEM equipped with EDS) and X-ray diffraction (XRD). The density, hardness, and bending strength of as-prepared copper-based composites were measured, and their tribological properties were investigated using UMT-2 tester. Results indicated that all copper-based composites showed decreased density and bending strength, but increased hardness in comparison with copper matrix. Besides, the incorporation of copper coated NbSe 2 improved the friction-reducing and anti-wear properties of copper matrix. Addition of copper coated CNT greatly enhanced the mechanical and tribological properties. In particular, when the content of copper coated CNT was 3 wt.%, the corresponding composite exhibited the best tribological properties. This was because NbSe 2 was distributed chaotically in matrix, which greatly improved the friction-reducing property of copper, while CNT with superior mechanical strength enhanced the wear resistance by increasing the load-carrying capacity. More importantly, copper layers coated on NbSe 2 and CNT favored the good interfacial combination between fillers and copper matrix showing beneficial effect for the stresses transferring from matrix to fillers

New WC-Cu thermal barriers for fusion applications: High temperature mechanical behaviour

Science.gov (United States)

Tejado, E.; Dias, M.; Correia, J. B.; Palacios, T.; Carvalho, P. A.; Alves, E.; Pastor, J. Y.

2018-01-01

The combination of tungsten carbide and copper as a thermal barrier could effectively reduce the thermal mismatch between tungsten and copper alloy, which are proposed as base armour and heat sink, respectively, in the divertor of future fusion reactors. Furthermore, since the optimum operating temperature windows for these divertor materials do not overlap, a compatible thermal barrier interlayer between them is required to guarantee a smooth thermal transition, which in addition may mitigate radiation damage. The aim of this work is to study the thermo-mechanical properties of WC-Cu cermets fabricated by hot pressing. Focus is placed on the temperature effect and composition dependence, as the volume fraction of copper varies from 25 to 50 and 75 vol%. To explore this behaviour, fracture experiments are performed within a temperature range from room temperature to 800 °C under vacuum. In addition, elastic modulus and thermal expansion coefficient are estimated from these tests. Results reveal a strong dependence of the performance on temperature and on the volume fraction of copper and, surprisingly, a slight percent of Cu (25 vol%) can effectively reduce the large difference in thermal expansion between tungsten and copper alloy, which is a critical point for in service applications. The thermal performance of these materials, together with their mechanical properties could indeed reduce the heat transfer from the PFM to the underlying element while supporting the high thermal stresses of the joint. Thus, the presence of these cermets could allow the reactor to operate above the ductile to brittle transition temperature of tungsten, without compromising the underlying materials.

Matrix composition effects on the tensile properties of tungsten-molybdenum heavy alloys

International Nuclear Information System (INIS)

Bose, A.; German, R.N.

1990-01-01

Tungsten-base heavy alloys are liquid-phase sintered from mixed tungsten, nickel, and iron powders. The sintered product is a composite consisting of interlaced tungsten and solidified matrix (W-Ni-Fe) phases. These alloys are most useful in applications requiring high density, strength, and toughness. The design of improved tungsten heavy alloys has been the subject of several research investigations. Much success has taken place through improved processing, but parallel compositional studies have resulted in new microstructure-property combinations. As part of these investigations, the Ni/Fe ratio has been varied, with the general conclusion that optimal strength and ductility occur with a ratio between 2 and 4. Brittle intermetallic phases can form outside of this composition range. Historically, a 7/3 Ni/Fe ratio has been selected for processing studies. Recently, others reported higher ductilities and impact energies for 90 and 93 pct W heavy alloys with the 8/2 Ni/Fe ratio. Alternatively, these alloys can be strengthened by both solid solution and grain size refinement through incorporation of molybdenum, tantalum, or rhenium. These additions are soluble in both the tungsten and matrix phases and retard solution-reprecipitation during liquid phase sintering. In this study, the alloy composition was varied in the nickel/iron ratio and molybdenum was partially substituted for tungsten. The sintered tensile properties are assessed vs these compositional variations

Effect of Physical Property and Surface Morphology of Copper Foil at Electrodeposition Parameter

Energy Technology Data Exchange (ETDEWEB)

Woo, Tae Gyu; Park, Il Song; Lee, Man Hyung; Seol, Kyeong Won [Chonbuk National University, Jeonju (Korea, Republic of)

2014-06-15

The effect of additives, current density and plated temperature on the surface morphology and physical property, during copper electrodeposition on polyimide (PI) film was investigated. Two kinds of additives, Cl and leveler (additive B), were used in this study. Electrochemical experiments were performed in conjunction with SEM, XRD and four-point probe to characterize the morphology and mechanical characteristics of copper electrodeposited in the presence of the additives. The surface roughness, crystal growth orientation and resistivity was controlled by the concentration of additive B. High resistivity and lower peel strength were observed on the surface of the copper layer electroplated in the electrolyte without additive B. However, a uniform surface, lower resistivity and high flexibility were obtained with a combination of 20 ppm Cl and 100 ppm additive B. Large particles were observed on the surface of the copper layer electroplated using a current density of 25 mA/cm{sup 2}, but a uniform surface and lower resistivity were obtained using a current density of 10 mA/cm{sup 2}. One of the required important properties of FCCL is flexibility of the copper foil. High flexibility of FCCL was obtained at a low current density, rather than a high current density. Moreover, a reasonable current density is 20 mA/cm{sup 2}, considering the productivity and mechanical properties of copper foil.

A problem to be solved for tungsten diagnostics through EUV spectroscopy in fusion devices

International Nuclear Information System (INIS)

Morita, S.; Murakami, I.; Sakaue, H.A.; Dong, C.F.; Goto, M.; Kato, D.; Oishi, T.; Huang, X.L.; Wang, E.H.

2013-01-01

Tungsten spectra have been observed from Large Helical Device (LHD) in extreme ultraviolet (EUV) wavelength ranges of 10-650Å. When the electron temperature is less than 2keV, the EUV spectra from plasma core are dominated by unresolved transition array (UTA) composing of a lot of spectral lines, e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W"+"2"4"-"+"3"3 in 15-35Å. In order to understand the UTA spectrum, the EUV spectra measured from LHD plasmas are compared to those measured from Compact electron Beam Ion Trap (CoBIT), in which the electron beam is operated with monoenergetic energy of E_e ≤ 2keV. The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The collisional-radiative (C-R) model has been developed to explain the UTA spectra from LHD in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database to examine the ionization balance determined by ionization and recombination rate coefficients. If the electron temperature is higher than 2keV, Zn-like WXLV (W"4"4"+) and Cu-like WXLVI (W"4"5"+) spectra can be observed in LHD. Such ions of W"4"4"+ and W"4"5"+ can exhibit much simpler atomic configuration compared to other ionization stages of tungsten. Quantitative analysis of the tungsten density is attempted for the first time on the radial profile of Zn-like WXLV (W"4"4"+) 4p-4s transition measured at 60.9Å, based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5x10"1"0 cm"-"3 at the plasma center of LHD is reasonably obtained. Finally, the present problem for tungsten diagnostics in fusion plasmas is summarized. (author)

Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

International Nuclear Information System (INIS)

Youchison, Dennis L.; North, Mart T.

2000-01-01

Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m 2 and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm 2 area. An impressive 10 kW of power was absorbed on an area of 24 cm 2 . Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m 2 using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented

Field-emission properties of transparent tungsten oxide nano-urchins

Energy Technology Data Exchange (ETDEWEB)

Kim, Do-Hyung [Kyungpook National University, Nano-applied Physics Laboratory, Department of Physics, Daegu (Korea, Republic of)

2012-09-15

The field-emission properties of transparent tungsten oxide nano-urchin (NU) films deposited on conducting glass substrates were examined. The novel crystalline tungsten oxide NUs consisted of nanowires added to a spherical shell. The WO{sub 2.72} NUs showed better field-emission properties than the WO{sub 3} NUs with a low turn-on field of approximately 5.8 V/{mu}m and a current density as high as 1.3 mA/cm{sup 2} at 7.2 V/mm. The WO{sub x} NUs films could be used in FE applications using a large-area glass substrate without the need for a catalyst and a mechanical rubbing or lift-up process. These results have implications for the enhancement of FE properties by further tuning the WO{sub x} phases. (orig.)

Influence of grain boundaries on the fracture toughness of tungsten alloys

International Nuclear Information System (INIS)

Gludovatz, B.; Faleschini, M.; Pippan, R.; Hoffmann, A.

2007-01-01

Full text of publication follows: Tungsten and tungsten alloys are possible candidates for future fusion reactors because of their high melting points, high thermal conductivity and their high erosion resistance. Since these materials have a body-centered cubic (bcc) structure, they show a typical change in fracture behaviour from brittle at low temperatures to ductile at high temperatures. For that reason the fracture behaviour of pure tungsten (W), potassium doped tungsten (AKS) and tungsten with 1 wt% La 2 O 3 (WL10) was studied, taking into account the influence of temperature and fabrication condition. Especially AKS has been studied to investigate the longitudinal splitting of the AKS-wires, the crack propagation direction with the lowest fracture toughness. This alloy subjected to intense deformation leads to a material with an elongated grain structure after recrystallization because of the potassium bubbles. Fracture toughness has been investigated by means of 3-point bending (3PB) specimens, double cantilever beam (DCB) specimens and compact tension (CT) specimens. Tests were performed in the range -196 deg. C to more than 1000 deg. C. Though all these materials show an expected increase in fracture toughness with increasing temperature, influences like texture, chemical composition, grain boundary segregation and dislocation density seem to have an extreme influence on the obtained results. These influences can especially be seen in the fracture behaviour and morphology, where two kinds of fracture can occur: on one hand the trans-crystalline and on the other hand the intercrystalline fracture. Therefore techniques like electron backscatter diffraction, auger electron spectroscopy and X-ray line profile analysis were used to determine the parameter influencing fracture toughness. Also new testing techniques have been devised and successfully applied. Additional tests like an 'in-situ EBSD' technique for investigating the formation of dislocations during

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

Studies of plasma interactions with tungsten targets in PF-1000U facility

Directory of Open Access Journals (Sweden)

Ladygina Maryna S.

2016-06-01

Full Text Available This paper presents results of experimental studies of tungsten samples of 99.95% purity, which were irradiated by intense plasma-ion streams. The behaviour of tungsten, and particularly its structural change induced by high plasma loads, is of great importance for fusion technology. The reported measurements were performed within a modified PF-1000U plasma-focus facility operated at the IFPiLM in Warsaw, Poland. The working gas was pure deuterium. In order to determine the main plasma parameters and to study the behaviour of impurities at different instants of the plasma discharge, the optical emission spectroscopy was used. The dependence of plasma parameters on the initial charging voltage (16, 19 and 21 kV was studied. Detailed optical measurements were performed during interactions of a plasma stream with the tungsten samples placed at the z-axis of the facility, at a distance of 6 cm from the electrode outlets. The recorded spectra showed distinct WI and WII spectral lines. Investigation of a target surface morphology, after its irradiation by intense plasma streams, was performed by means of an optical microscope. The observations revealed that some amounts of the electrodes material (mainly copper were deposited upon the irradiated sample surface. In all the cases, melted zones were observed upon the irradiated target surface, and in experiments performed at the highest charging voltage there were formed some cracks.

High-speed collision of copper nanoparticle with aluminum surface: Molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Pogorelko, Victor V., E-mail: vik_ko83@mail.ru [Chelyabinsk State University, Bratiev Kashirinykh 129, 454001 Chelyabinsk (Russian Federation); South Ural State University (National Research University), Lenin Prospect 76, 454080 Chelyabinsk (Russian Federation); Mayer, Alexander E., E-mail: mayer@csu.ru [Chelyabinsk State University, Bratiev Kashirinykh 129, 454001 Chelyabinsk (Russian Federation); South Ural State University (National Research University), Lenin Prospect 76, 454080 Chelyabinsk (Russian Federation); Krasnikov, Vasiliy S., E-mail: vas.krasnikov@gmail.com [Chelyabinsk State University, Bratiev Kashirinykh 129, 454001 Chelyabinsk (Russian Federation); South Ural State University (National Research University), Lenin Prospect 76, 454080 Chelyabinsk (Russian Federation)

2016-12-30

Highlights: • High-speed nanoparticle impact induces shock waves and intensive plastic deformation. • Lattice orientation strongly influences on the deformation degree. • Plastic deformation goes through nucleation, growth and separation of semi-loops. • Medium impact energy and elevated temperature are optimal for high-quality coating. • High impact velocity and room temperature lead to plastic deformation and coating. - Abstract: We investigate the effect of the high-speed collision of copper nanoparticles with aluminum surface by means of molecular dynamic simulations. Studied diameter of nanoparticles is varied within the range 7.2–22 nm and the velocity of impact is equal to 500 or 1000 m/s. Dislocation analysis shows that a large quantity of dislocations is formed within the impact area. Overall length of dislocations is determined, first of all, by the impact velocity and by the size of incident copper nanoparticle, in other words, by the kinetic energy of the nanoparticle. Dislocations occupy the total volume of the impacted aluminum single crystal layer (40.5 nm in thickness) in the form of intertwined structure in the case of large kinetic energy of the incident nanoparticle. Decrease in the initial kinetic energy or increase in the layer thickness lead to restriction of the penetration depth of the dislocation net; formation of separate dislocation loops is observed in this case. Increase in the initial system temperature slightly raises the dislocation density inside the bombarded layer and considerably decreases the dislocation density inside the nanoparticle. The temperature increase also leads to a deeper penetration of the copper atoms inside the aluminum. Additional molecular dynamic simulations show that the deposited particles demonstrate a very good adhesion even in the case of the considered relatively large nanoparticles. Medium energy of the nanoparticles corresponding to velocity of about 500 m/s and elevated temperature of the

High-speed collision of copper nanoparticle with aluminum surface: Molecular dynamics simulation

International Nuclear Information System (INIS)

Pogorelko, Victor V.; Mayer, Alexander E.; Krasnikov, Vasiliy S.

2016-01-01

Highlights: • High-speed nanoparticle impact induces shock waves and intensive plastic deformation. • Lattice orientation strongly influences on the deformation degree. • Plastic deformation goes through nucleation, growth and separation of semi-loops. • Medium impact energy and elevated temperature are optimal for high-quality coating. • High impact velocity and room temperature lead to plastic deformation and coating. - Abstract: We investigate the effect of the high-speed collision of copper nanoparticles with aluminum surface by means of molecular dynamic simulations. Studied diameter of nanoparticles is varied within the range 7.2–22 nm and the velocity of impact is equal to 500 or 1000 m/s. Dislocation analysis shows that a large quantity of dislocations is formed within the impact area. Overall length of dislocations is determined, first of all, by the impact velocity and by the size of incident copper nanoparticle, in other words, by the kinetic energy of the nanoparticle. Dislocations occupy the total volume of the impacted aluminum single crystal layer (40.5 nm in thickness) in the form of intertwined structure in the case of large kinetic energy of the incident nanoparticle. Decrease in the initial kinetic energy or increase in the layer thickness lead to restriction of the penetration depth of the dislocation net; formation of separate dislocation loops is observed in this case. Increase in the initial system temperature slightly raises the dislocation density inside the bombarded layer and considerably decreases the dislocation density inside the nanoparticle. The temperature increase also leads to a deeper penetration of the copper atoms inside the aluminum. Additional molecular dynamic simulations show that the deposited particles demonstrate a very good adhesion even in the case of the considered relatively large nanoparticles. Medium energy of the nanoparticles corresponding to velocity of about 500 m/s and elevated temperature of the

Qualification and post-mortem characterization of tungsten mock-ups exposed to cyclic high heat flux loading

Energy Technology Data Exchange (ETDEWEB)

Pintsuk, G., E-mail: g.pintsuk@fz-juelich.de [Forschungszentrum Jülich GmbH, Euratom Association, D-52425 Jülich (Germany); Bobin-Vastra, I.; Constans, S. [AREVA NP PTCMI-F, Centre Technique, Fusion, F-71200 Le Creusot (France); Gavila, P. [Fusion for Energy, E-08019 Barcelona (Spain); Rödig, M. [Forschungszentrum Jülich GmbH, Euratom Association, D-52425 Jülich (Germany); Riccardi, B. [Fusion for Energy, E-08019 Barcelona (Spain)

2013-10-15

Highlights: • We characterize tungsten mono-block components after exposure to ITER relevant heat loads. • We qualify the manufacturing technology, i.e., hot isostatic pressing and hot radial pressing, and repair technologies. • We determine the microstructural influences, i.e., rod vs. plate material, on the damage evolution. • Needle like microstructures increase the risk of deep crack formation due to a limited fracture strength. -- Abstract: In order to evaluate the option to start the ITER operation with a full tungsten (W) divertor, high heat flux tests were performed in the electron beam facility FE200, Le Creusot, France. Thereby, in total eight small-scale and three medium-scale monoblock mock-ups produced with different manufacturing technologies and different tungsten grades were exposed to cyclic steady state heat loads. The applied power density ranges from 10 to 20 MW/m{sup 2} with a maximum of 1000 cycles at each particular loading step. Finally, on a reduced number of tiles, critical heat flux tests in the range of 30 MW/m{sup 2} were performed. Besides macroscopic and microscopic images of the loaded surface areas, detailed metallographic analyses were performed in order to characterize the occurring damages, i.e., crack formation, recrystallization, and melting. Thereby, the different joining technologies, i.e., hot radial pressing (HRP) vs. hot isostatic pressing (HIP) of tungsten to the Cu-based cooling tube, were qualified showing a higher stability and reproducibility of the HIP technology also as repair technology. Finally, the material response at the loaded top surface was found to be depending on the material grade, microstructural orientation, and recrystallization state of the material. These damages might be triggered by the application of thermal shock loads during electron beam surface scanning and not by the steady state heat load only. However, the superposition of thermal fatigue loads and thermal shocks as also expected

Polaron interaction energies in reduced tungsten trioxide

International Nuclear Information System (INIS)

Iguchi, E.; Salje, E.; Tilley, R.J.D.

1981-01-01

Consideration of the properties of reduced tungsten trioxide suggest that the mobile charge carriers are polarons. As it is uncertain how the presence of polarons will influence the microstructures of the crystallographic shear (CS) planes present in reduced tungsten trioxide we have calculated both the polaron-CS plane and polaron-polaron interaction energy for a variety of circumstances. Three CS plane geometries were considered, (102), (103), and (001) CS plane arrays, and the nominal compositions of the crystals ranged from WO 2 70 to WO 3 0 . The polarons were assumed to have radii from 0.6 to 1.0 nm and the polaron-CS plane electrostatic interaction was assumed to be screened. The results suggest that for the most part the total interaction energy is small and is unlikely to be of major importance in controlling the microstructures found in CS planes. However, at very high polaron densities the interaction energy could be appreciable and may have some influence on the existence range of CS phases

Influence of Cooling Rate in High-Temperature Area on Hardening of Deposited High-Cutting Chrome-Tungsten Metal

OpenAIRE

Malushin, N. N.; Valuev, Denis Viktorovich; Valueva, Anna Vladimirovna; Serikbol, A.; Borovikov, I. F.

2015-01-01

The authors study the influence of cooling rate in high-temperature area for thermal cycle of high-cutting chrome-tungsten metal weld deposit on the processes of carbide phase merging and austenite grain growth for the purpose of providing high hardness of deposited metal (HRC 64-66).

Development of high-current-density LAB6 thermionic emitters for a space-charge-limited electron gun

International Nuclear Information System (INIS)

Herniter, M.E.; Getty, W.D.

1987-01-01

An electron gun has been developed for investigation of high current density, space charge limited operation of a lenthanum hexaboride (LaB 6 ) thermionic cathode. The 2.8 cm 2 cathode disk is heated by electron bombardment from a tungsten filament. For LaB 6 cathode temperatures greater than 1600 0 C it has been found that evaporation from the LaB 6 causes an increase in the tungsten filament emission, leading to an instability in the bombardment heating system. This instability has been investigated and eliminated by using a graphite disk in place of the LaB 6 cathode or by shielding the filament from the LaB 6 cathode by placing the LaB 6 in a graphite cup and bombarding the cup. The graphite disk has been heated to 1755 0 C with 755 W of heating power, and the shielded LaB 6 cathode has been heated to 1695 0 C. This temperature range is required for emission current densities in the 30 Acm 2 range. It is believed that the evaporation of lanthanum lowers the tungsten work function. In electron-gun use, the LaB 6 cathode has been operated up to 6.7 Acm 2 at 36 kV. A 120 kV Marx generator has been built to allow operation up to 40 Acm 2

Results of high heat flux tests of tungsten divertor targets under plasma heat loads expected in ITER and tokamaks (review)

Energy Technology Data Exchange (ETDEWEB)

Budaev, V. P., E-mail: budaev@mail.ru [National Research Centre Kurchatov Institute (Russian Federation)

2016-12-15

Heat loads on the tungsten divertor targets in the ITER and the tokamak power reactors reach ~10MW m{sup −2} in the steady state of DT discharges, increasing to ~0.6–3.5 GW m{sup −2} under disruptions and ELMs. The results of high heat flux tests (HHFTs) of tungsten under such transient plasma heat loads are reviewed in the paper. The main attention is paid to description of the surface microstructure, recrystallization, and the morphology of the cracks on the target. Effects of melting, cracking of tungsten, drop erosion of the surface, and formation of corrugated and porous layers are observed. Production of submicron-sized tungsten dust and the effects of the inhomogeneous surface of tungsten on the plasma–wall interaction are discussed. In conclusion, the necessity of further HHFTs and investigations of the durability of tungsten under high pulsed plasma loads on the ITER divertor plates, including disruptions and ELMs, is stressed.

Test data on electrical contacts at high surface velocities and high current densities for homopolar generators

International Nuclear Information System (INIS)

Brennan, M.; Tolk, K.M.; Weldon, W.F.; Rylander, H.G.; Woodson, H.H.

1977-01-01

Test data is presented for one grade of copper graphite brush material, Morganite CMlS, over a wide range of surface velocities, atmospheres, and current densities that are expected for fast discharge (<100 ms) homopolar generators. The brushes were run on a copper coated 7075-T6 aluminum disk at surface speeds up to 277 m/sec. One electroplated copper and three flame sprayed copper coatings were used during the tests. Significant differences in contact voltage drops and surface mechanical properties of the copper coatings were observed

Damage process of high purity tungsten coatings by hydrogen beam heat loads

International Nuclear Information System (INIS)

Tamura, S.; Tokunaga, K.; Yoshida, N.; Taniguchi, M.; Ezato, K.; Sato, K.; Suzuki, S.; Akiba, M.; Tsunekawa, Y.; Okumiya, M.

2005-01-01

To investigate the synergistic effects of heat load and hydrogen irradiation, cyclic heat load tests with a hydrogen beam and a comparable electron beam were performed for high purity CVD-tungsten coatings. Surface modification was examined as a function of the peak temperature by changing the heat flux. Scanning Electron Microscopy analysis showed that the surface damage caused by the hydrogen beam was more severe than that by the electron beam. In the hydrogen beam case, cracking at the surface occurred at all peak temperatures examined from 300 deg. C to 1600 deg. C. These results indicate that the injected hydrogen induces embrittlement for the CVD-tungsten coating

Effect of magnetic flux-densities of up to 0.1 Tesla on copper electrodeposition

International Nuclear Information System (INIS)

Cifuentes, L.; Artigas, M.; Riveros, G.; Warczok, A.

2003-01-01

The effect of magnetic flux densities (B) between 0.0 and 0.1 Tesla on cathode and anode over potentials, cell voltage and electro deposit quality was determined fro a lab-scale copper electrowinning cell which operates at industrial current, density values. Cell voltage decreases with increasing B. The cathodic overpotential decreases by 30% when B increases from 0.0 to 0.1 T. The anodic overpotential also decreases with increasing B, but this effect is six times less than the corresponding effect on the cathodic overpotential. Cathodic effects can be predicted by an expression derived from electrochemical kinetics and magnetohydrodynamic theory. Anodic effects cannot be predicted in the same way. The size of grains and intergranular voids decreases and the surface of the electro deposit becomes smoother as B increases, which means that, in the studied conditions, the quality of the produced copper deposits improves. (Author) 26 refs

Efficacy of Tantalum Tungsten Alloys for Diffusion Barrier Applications

Science.gov (United States)

Smathers, D. B.; Aimone, P. R.

2017-12-01

Traditionally either Niobium, Tantalum or a combination of both have been used as diffusion barriers in Nb3Sn Multi-filament wire. Vanadium has also been used successfully but the ultimate RRR of the copper is limited unless an external shell of Niobium is included. Niobium is preferred over Tantalum when alternating current losses are not an issue as the Niobium will react to form Nb3Sn. Pure Tantalum tends to deform irregularly requiring extra starting thickness to ensure good barrier qualities. Our evaluations showed Tantalum lightly alloyed with 3 wt% Tungsten is compatible with the wire drawing process while deforming as well as or better than pure Niobium. Ta3wt%W has been processed as a single barrier and as a distributed barrier to fine dimensions. In addition, the higher modulus and strength of the Tantalum Tungsten alloy improves the overall tensile properties of the wire.

Influence of Cooling Rate in High-Temperature Area on Hardening of Deposited High-Cutting Chrome-Tungsten Metal

International Nuclear Information System (INIS)

Malushin, N N; Valuev, D V; Valueva, A V; Serikbol, A; Borovikov, I F

2015-01-01

The authors study the influence of cooling rate in high-temperature area for thermal cycle of high-cutting chrome-tungsten metal weld deposit on the processes of carbide phase merging and austenite grain growth for the purpose of providing high hardness of deposited metal (HRC 64-66). (paper)

Chemical etching of Tungsten thin films for high-temperature surface acoustic wave-based sensor devices

Energy Technology Data Exchange (ETDEWEB)

Spindler, M., E-mail: m.spindler@ifw-dresden.de [IFW Dresden, SAWLab Saxony, P.O. Box 270116, D-01171 Dresden (Germany); Herold, S.; Acker, J. [BTU Cottbus – Senftenberg, Faculty of Sciences, P.O. Box 101548, 01968 Senftenberg (Germany); Brachmann, E.; Oswald, S.; Menzel, S.; Rane, G. [IFW Dresden, SAWLab Saxony, P.O. Box 270116, D-01171 Dresden (Germany)

2016-08-01

Surface acoustic wave devices are widely used as wireless sensors in different application fields. Recent developments aimed to utilize those devices as temperature sensors even in the high temperature range (T > 300 °C) and in harsh environmental conditions. Therefore, conventional materials, which are used for the substrate and for the interdigital transducer finger electrodes such as multilayers or alloys based on Al or Cu have to be exchanged by materials, which fulfill some important criteria regarding temperature related effects. Electron beam evaporation as a standard fabrication method is not well applicable for depositing high temperature stable electrode materials because of their very high melting points. Magnetron sputtering is an alternative deposition process but is also not applicable for lift-off structuring without any further improvement of the structuring process. Due to a relatively high Ar gas pressure of about 10{sup −1} Pa, the sidewalls of the photoresist line structures are also covered by the metallization, which subsequently prevents a successful lift-off process. In this study, we investigate the chemical etching of thin tungsten films as an intermediate step between magnetron sputtering deposition of thin tungsten finger electrodes and the lift-off process to remove sidewall covering for a successful patterning process of interdigital transducers. - Highlights: • We fabricated Tungsten SAW Electrodes by magnetron sputtering technology. • An etching process removes sidewall covering of photoresist, which allows lift-off. • Tungsten etching rates based on a hydrogen peroxide solutions were determined.

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

Deuterium-induced nanostructure formation on tungsten exposed to high-flux plasma

NARCIS (Netherlands)

Xu, H.Y.; De Temmerman, G.C.; Luo, G.-N.; Jia, Y.Z.; Yuan, Y.; Fu, B.Q.; Godfrey, A.; Liu, W.

2015-01-01

PLASMA-SURFACE INTERACTIONS 21 — Proceedings of the 21st International Conference on Plasma-Surface Interactions in Controlled Fusion Devices Kanazawa, Japan May 26-30, 2014 Surface topography of polycrystalline tungsten (W) have been examined after exposure to a low-energy (38 eV/D), high-flux

Radial density distribution of a warm dense plasma formed by underwater electrical explosion of a copper wire

Science.gov (United States)

Nitishinskiy, M.; Yanuka, D.; Virozub, A.; Krasik, Ya. E.

2017-12-01

Time- and space-resolved evolution of the density (down to 0.07 of solid state density) of a copper wire during its microsecond timescale electrical explosion in water was obtained by X-ray backlighting. In the present research, a flash X-ray source of 20 ns pulse-width and >60 keV photon energy was used. The conductivity of copper was evaluated for a temperature of 10 kK and found to be in good agreement with the data obtained in earlier experiments [DeSilva and Katsouros, Phys. Rev. E 57, 5945 (1998) and Sheftman and Krasik, Phys. Plasmas 18, 092704 (2011)] where only electrical and optical diagnostics were applied. Magneto-hydrodynamic simulation shows a good agreement between the simulated and experimental waveforms of the current and voltage and measured the radial expansion of the exploding wire. Also, the radial density distribution obtained by an inverse Abel transform analysis agrees with the results of these simulations. Thus, the validity of the equations of state for copper and the conductivity model used in the simulations was confirmed for the parameters of the exploding wire realized in the present research.

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

Evaluation of dislocation density in copper and brass α deformed by XRD peak width analysis

International Nuclear Information System (INIS)

Sousa, Talita Gama de

2014-01-01

The determination of dislocation density in metallic materials has been available for many years in scientific environment. This is due to the fact that the dislocations are the main responsible for plastic deformation, which, thereafter, markedly influences the mechanical properties. In this work, the dislocation density was analyzed through peak broadening of Xray diffraction (XRD) using Convolutional Multiple Whole Profile (CMWP) program. The measurements obtained by XRD were compared with those obtained from images observed by transmission electronic microscopy (TEM). The materials used in this study were pure copper and brass α as alloy 268 (6 % Cu and 34 % Zn), deformed by rolling and ECA (equal channel angular extrusion) processes. The results indicate that the XRD is a powerful tool for the characterization of the microstructure in relation to the dislocation density, as they were consistent to the TEM measurements, and also showed good relationship with measurements of hardness. Furthermore, through the dislocation density it was possible to verify the influence of stacking fault energy (SFE) in the evolution of the copper samples deformation process and its alloy, and that the presence of texture in rolled samples did not impair the measurements obtained by XRD technique. (author)

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)

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

Process for improving the low temperature ductility of tungsten-base composites

International Nuclear Information System (INIS)

Zukas, E.G.

1975-05-01

At temperatures below about 100 0 C, liquid-phase-sintered tungsten-base composites fail in a brittle manner because of the formation of cleavage cracks in the tungsten spheroids. Improving the ductility, then, would require some alloying addition or treatment which would improve the ductility of these spheroids, or some method of changing the stress distribution, such as putting the surface in compression, which would reduce stress concentrations and thereby require a higher load to initiate fracture. The ductilizing process used here consists of coating the composite with a ductile metal followed by heat treating at a high enough temperature to insure sufficient diffusion so that the coat and base become integral. The ductile coat is now the 'piece' surface, and the initiation of cleavage cracks requires much greater stresses. Coats of copper, nickel, gold, and cobalt have been used successfully. A possible added advantage is that the surface properties can now be controlled if certain reflective properties or corrosion resistance are needed. Also soldering or low temperature brazing operations are feasible, allowing the construction or assembly of intricate shapes which could not be accomplished previously. (U.S.)

Copper alloys for high heat flux structure applications

International Nuclear Information System (INIS)

Zinkle, S.J.; Fabritsiev, S.A.

1994-01-01

The mechanical and physical properties of copper alloys are reviewed and compared with the requirements for high heat flux structural applications in fusion reactors. High heat flux structural materials must possess a combination of high thermal conductivity and high mechanical strength. The three most promising copper alloys at the present time are oxide dispersion-strengthened copper (Cu-Al 2 O 3 ) and two precipitation-hardened copper alloys (Cu-Cr-Zr and Cu-Ni-Be). These three alloys are capable of room temperature yield strengths >400 MPa and thermal conductivities up to 350 W/m-K. All of these alloys require extensive cold working to achieve their optimum strength. Precipitation-hardened copper alloys such Cu-Cr-Zr are susceptible to softening due to precipitate overaging and recrystallization during brazing, whereas the dislocation structure in Cu-Al 2 O 3 remains stabilized during typical high temperature brazing cycles. All three alloys exhibit good resistance to irradiation-induced softening and void swelling at temperatures below 300 degrees C. The precipitation-strengthened allows typically soften during neutron irradiation at temperatures above about 300 degrees C and therefore should only be considered for applications operating at temperatures 2 O 3 ) is considered to be the best candidate for high heat flux structural applications

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

Science.gov (United States)

Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

2013-10-01

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

International Nuclear Information System (INIS)

Kühn-Kauffeldt, M; Marques, J-L; Forster, G; Schein, J

2013-01-01

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned

Demonstration of multi-generational growth of tungsten nanoparticles in hydrogen plasma using in situ laser extinction method

Science.gov (United States)

Ouaras, K.; Lombardi, G.; Hassouni, K.

2018-03-01

For the first time, we demonstrate that tungsten (W) nanoparticles (NPs) are created when a tungsten target is exposed to low-pressure, high density hydrogen plasma. The plasma was generated using a novel dual plasma system combining a microwave discharge and a pulsed direct-current (DC) discharge. The tungsten surface originates in the multi-generational formation of a significant population of 30-70 nm diameter particles when the W cathode is biased at ~  -1 kV and submitted to ~1020 m2 s-1 H+/H2+ /H3+ ions flux. The evidenced NPs formation should be taking into account as one of the consequence of the plasma surface interaction outcomes, especially for fusion applications.

Synthesis and field emission characteristics of carbon nanocoils with a high aspect ratio supported by copper micro-tips

International Nuclear Information System (INIS)

Sung, Woo Yong; Ok, Jong Girl; Kim, Wal Jun; Lee, Seung Min; Yeon, Soon Chang; Lee, Ho Young; Kim, Yong Hyup

2007-01-01

Carbon nanocoils (CNCs) were synthesized via thermal chemical vapour deposition (CVD) with C 2 H 2 and NH 3 gases at 600 deg. C. A Ni catalyst was placed upon the copper micro-tip structures that were fabricated on a silicon substrate. Our CNCs had a long rope shape with a length not exceeding 100 μm and a nanoscale diameter. The copper micro-tips were formed through high current pulse electroplating, which played a significant role in characterizing our CNCs. The CNCs grown on the copper micro-tips showed outstanding field emission performance and long-term stability. Their turn-on field, defined as that at a current density of 10 μA cm -2 , was 1.30 V μm -1 and the maximum current density reached 11.17 mA cm -2 at an electric field of 2.39 V μm -1

Thermal shock tests to qualify different tungsten grades as plasma facing material

Science.gov (United States)

Wirtz, M.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Uytdenhouwen, I.

2016-02-01

The electron beam device JUDITH 1 was used to establish a testing procedure for the qualification of tungsten as plasma facing material. Absorbed power densities of 0.19 and 0.38 GW m-2 for an edge localized mode-like pulse duration of 1 ms were chosen. Furthermore, base temperatures of room temperature, 400 °C and 1000 °C allow investigating the thermal shock performance in the brittle, ductile and high temperature regime. Finally, applying 100 pulses under all mentioned conditions helps qualifying the general damage behaviour while with 1000 pulses for the higher power density the influence of thermal fatigue is addressed. The investigated reference material is a tungsten product produced according to the ITER material specifications. The obtained results provide a general overview of the damage behaviour with quantified damage characteristics and thresholds. In particular, it is shown that the damage strongly depends on the microstructure and related thermo-mechanical properties.

On the problem of high temperature embrittlement of tungsten

International Nuclear Information System (INIS)

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

1983-01-01

The paper presents results of a complex physicomechanical study of tungsten crack resistance. The presence of a descending portion of curve in a temperature range from Tsub(x)sup(b) to 2 000 deg C is a characteristic feature of Ksub(Ic) temperature dependence. Changes in the tungsten physical state under isotherma heating were analysed on the basis of the results of metallographic, X-ray and electron fractographic studies. Certain results obtained are shown to be contradicting

Ductile-to-brittle transition behavior of tungsten-copper composites

International Nuclear Information System (INIS)

Hiraoka, Y.; Inoue, T.; Akiyoshi, N.; Yoo, M.K.

2001-01-01

A series of W-Cu composites were fabricated alternatively by infiltration method (19-48 vol% Cu) or by pressing and sintering method (20-80 vol% Cu), and three-point bend tests were carried out at temperatures between 77 and 363 K. Ductile-to-brittle transition behavior of the composite was investigated and also effects of Cu content as well as fabrication method on the strength and ductility of the composite were discussed. Results were summarized as follows. (1) Composite containing 19-40 vol% of copper demonstrated ductile-to-brittle transition behavior. Transition temperature tended to decrease substantially with increasing Cu content, though ductility of the composite by infiltration method was much better than that by pressing and sintering method. (2) Composite containing 48-80 vol% of copper did not demonstrate transition behavior regardless of fabrication method. (3) These results were well interpreted in terms of microstructure and fractography. (author)

Electrochemical synthesis of highly crystalline copper nanowires

International Nuclear Information System (INIS)

Kaur, Amandeep; Gupta, Tanish; Kumar, Akshay; Kumar, Sanjeev; Singh, Karamjeet; Thakur, Anup

2015-01-01

Copper nanowires were fabricated within the pores of anodic alumina template (AAT) by template synthesis method at pH = 2.9. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the structure, morphology and composition of fabricated nanowires. These characterizations revealed that the deposited copper nanowires were highly crystalline in nature, dense and uniform. The crystalline copper nanowires are promising in application of future nanoelectronic devices and circuits

High temperature mechanical properties of unirradiated dispersion strengthened copper

International Nuclear Information System (INIS)

Gentzbittel, J.M.; Rigollet, C.; Robert, G.

1994-01-01

Oxide Dispersion Strengthened (ODS) copper material, due to its excellent thermal conductivity associated with a high temperature strength is a candidate material for structural applications as divertor plasma facing components of thermonuclear fusion reactor. Tensile and creep results of oxide dispersion strengthened copper are presented. The most important features of ODS copper high temperature behaviour are the high strength corresponding to low creep rates, high stress creep rate dependence, a poor ductility and a brittleness which result in a premature creep fracture at high applied stress. (R.P.) 2 refs.; 6 figs

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.

High-purity tungsten powder: spheroidizing, properties and use in electronics

International Nuclear Information System (INIS)

Kapustin, V.I.; Burov, I.V.

1999-01-01

A study was made on the method of spheroidizing of tungsten powder in plasma of super high-frequency (SHF) discharge for formation of matrices, cathodes with regular porous structure. Kinetics of interphase interaction in the basic W-Y 2 O 3 cathode system was investigated. Possibility of using small additions of Re 2 Yintermetallic compound as an activator of emission-active component of cathodes was analyzed, High efficiency of plasma SHF-treatment with the use of laminar plasma flow is shown [ru

Silicon-embedded copper nanostructure network for high energy storage

Science.gov (United States)

Yu, Tianyue

2016-03-15

Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

Silicon-embedded copper nanostructure network for high energy storage

Energy Technology Data Exchange (ETDEWEB)

Yu, Tianyue

2018-01-23

Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

Demands made on high-purity copper for special purposes

International Nuclear Information System (INIS)

Roettges, D.

1977-01-01

The properties (electrical resistivity, residual impurities) of high-purity copper produced on a technical scale are reported as well as its practical applications. The paper discusses a high-oxygen copper (SV) with low residual resistivity at low temperatures and an oxygen-free (hydrogen-stable) copper (BE electronic) with low gas content. The SV quality has been specially developed for use as stabilizer in superconductors while the BE quality is used in high and ultrahigh vacuum. (GSC) [de

Development of technology of high density LEU dispersion fuel fabrication

International Nuclear Information System (INIS)

Wiencek, T.; Totev, T.

2007-01-01

Advanced Materials Fabrication Facilities at Argonne National Laboratory have been involved in development of LEU dispersion fuel for research and test reactors from the beginning of RERTR program. This paper presents development of technology of high density LEU dispersion fuel fabrication for full size plate type fuel elements. A brief description of Advanced Materials Fabrication Facilities where development of the technology was carried out is given. A flow diagram of the manufacturing process is presented. U-Mo powder was manufactured by the rotating electrode process. The atomization produced a U-Mo alloy powder with a relatively uniform size distribution and a nearly spherical shape. Test plates were fabricated using tungsten and depleted U-7 wt.% Mo alloy, 4043 Al and Al-2 wt% Si matrices with Al 6061 aluminum alloy for the cladding. During the development of the technology of manufacturing of full size high density LEU dispersion fuel plates special attention was paid to meet the required homogeneity, bonding, dimensions, fuel out of zone and other mechanical characteristics of the plates.

GEMAS - Tin and Tungsten: possible sources of enriched concentrations in soils in European countries

Science.gov (United States)

João Batista, Maria; Filipe, Augusto; Reimann, Clemens

2014-05-01

southern soils and SiO2 is higher in loess sediments region, in the North German-Poland basin and in the Paris basin. Organic matter may immobilise these metals and silica content influences metallic elements concentrations in soils. Natural processes of soil development, land management of agricultural soils and population density all together may be responsible for higher concentrations of W in the soils of Netherlands Germany, Belgium, Switzerland and northeast France which seems not related with Sn-W mineral provinces. Tin and tungsten are enriched in the Precambrian shields compared to the Caledonian shields soils in the northern countries, although in northern countries climatic conditions may play the most important role in these elements concentrations. Tin and tungsten and tin or tungsten alone or in association of precious metals, copper, uranium, niobium, beryllium, titanium altogether were extracted in 650 small or median size mines in Portugal. Except tin in Neves Corvo mine of the Iberian Pyrite Belt the rest of these mines occurred in the Variscides granitic intrusions region. Tin and tungsten concentrations are therefore well reflected in the northern Portugal soils. At the GEMAS density of sampling pollution and local natural phenomena are not reflected in mapping but this important province is well delimited.

X-ray spectrum microanalysis of copper and stainless steel surface layer after electroerosion machining

International Nuclear Information System (INIS)

Abdukarimov, Eh.T.; Saidinov, S.Ya.

1989-01-01

The results of experimental investigations of the surface layer of copper and steel 12Kh18N10T after electroerrosion treatment by a rotating tungsten electrode in natural and distilled water are presented. It is established that the quantity of electrode material transferred to the surface of the steel treated grows with the spark discharge energy increase. Tungsten concentration in the surface layer reaches 5-10% with the average depth of penetration 40-50 μm

Separation of Molybdenum from Acidic High-Phosphorus Tungsten Solution by Solvent Extraction

Science.gov (United States)

Li, Yongli; Zhao, Zhongwei

2017-10-01

A solvent-extraction process for deep separation of molybdenum from an acidic high-phosphate tungsten solution was developed using tributyl phosphate (TBP) as the extractant and hydrogen peroxide (H2O2) as a complexing agent. The common aqueous complexes of tungsten and molybdenum (PMoxW12-xO40 3-, x = 0-12) are depolymerized to {PO4[Mo(O)2(O-O)]4}3- and {PO4[W(O)2(O-O)]4}3- by H2O2. The former can be preferentially extracted by TBP. The extractant concentration, phase contact time, H2O2 dosage, and H2SO4 concentration were optimized. By employing 80% by volume TBP, O:A = 1:1, 1.0 mol/L H2SO4, 1.0 mol/L H3PO4, a contact time of 2 min, and a molar ratio of H2O2/(W + Mo) equal to 1.5, 60.2% molybdenum was extracted in a single stage, while limiting tungsten co-extraction to 3.2%. An extraction isotherm indicated that the raffinate could be reduced to <0.1 g/L Mo in six stages of continuous counter-current extraction.

Tungsten particle reinforced Al 5083 composite with high strength and ductility

Energy Technology Data Exchange (ETDEWEB)

Bauri, Ranjit, E-mail: rbauri@iitm.acin; Yadav, Devinder; Shyam Kumar, C.N.; Balaji, B.

2015-01-03

Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process.

Impact of microstructure on the plasma performance of industrial and high-end tungsten grades

Energy Technology Data Exchange (ETDEWEB)

Pintsuk, G., E-mail: g.pintsuk@fz-juelich.de [Forschungszentrum Jülich, EURATOM Association, 52428 Jülich (Germany); Loewenhoff, Th. [Forschungszentrum Jülich, EURATOM Association, 52428 Jülich (Germany)

2013-07-15

Tungsten and tungsten alloys are actually the primary choice as plasma facing materials for future fusion reactors. Thereby, the material’s response to the different loading conditions occurring in a tokamak is strongly depending on the material properties and therefore the material’s microstructure. This is on the one hand controlled via the manufacturing process and/or the material’s composition and on the other hand by the operational conditions causing recrystallization and melting, and subsequently not only a modified microstructure but also locally a modified composition. The influence of the variation in microstructure is addressed and the pros and cons for using the respective materials and tungsten in general in a fusion environment with steady state and transient thermal loads are outlined. While roughening and the related cracking can hardly be avoided, melting will thwart all efforts to establish a high end microstructure with defined directional properties.

Impact of microstructure on the plasma performance of industrial and high-end tungsten grades

International Nuclear Information System (INIS)

Pintsuk, G.; Loewenhoff, Th.

2013-01-01

Tungsten and tungsten alloys are actually the primary choice as plasma facing materials for future fusion reactors. Thereby, the material’s response to the different loading conditions occurring in a tokamak is strongly depending on the material properties and therefore the material’s microstructure. This is on the one hand controlled via the manufacturing process and/or the material’s composition and on the other hand by the operational conditions causing recrystallization and melting, and subsequently not only a modified microstructure but also locally a modified composition. The influence of the variation in microstructure is addressed and the pros and cons for using the respective materials and tungsten in general in a fusion environment with steady state and transient thermal loads are outlined. While roughening and the related cracking can hardly be avoided, melting will thwart all efforts to establish a high end microstructure with defined directional properties

Robust superhydrophobic tungsten oxide coatings with photochromism and UV durability properties

Energy Technology Data Exchange (ETDEWEB)

Jiang, Ting [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan, 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan, 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

2016-11-30

Highlights: • Superhydrophobic tungsten oxide (TO) coatings with a water contact angle (WCA) of 155° and rolling angle of 3.5° were developed. • The superhydrophobic coatings have excellent mechanical robustness and UV durability. • The superhydrophobic TO coatings show the reversible convert of photochromism. • The coating exhibited excellent self-cleaning behavior due to its high WCA and low rolling angle. - Abstract: Robust superhydrophobic tungsten oxide (TO) coatings with a water contact angle (WCA) of 155° were developed for photochromism via a facile and substrate-independent route. Importantly, after scatch test on both a single and two orthogonal direction, the TO coating still exhibited superhydrophobic behavior, indicating excellent mechanical robustness. It is worth mentioning that the superhydrophobic TO coatings showed the reversible convert of photochromism of WO{sub 3} induced by alternating UV and visible light irradiation. Besides that, the TO coating remained superhydrophobicity after UV irradiation for 36 h, showing excellent UV durability. In addition, the coating showed good resistance to acidic droplets. Moreover, it can also be applied on other substrates, such as copper mesh, steel, paper and fiber. The coating exhibited excellent self-cleaning behavior due to its high WCA and low rolling angle. Overall, this work is a promising approach to design and produce functional superhydrophobic coatings for various substrates.

Experimental tests concerning the use of the tungsten-copper couple design concept on the divertor system

International Nuclear Information System (INIS)

Brossa, F.; Ghiselli, P.; Tommei, G.; Piatti, G.; Schiller, P.

1983-01-01

The technique of brazing tungsten armour to the Cu heat sink to form divertor plates for the INTOR fusion reactor raises fabrication problems to bypass thermal stresses produced by the high thermal flux and the differences in the thermal expansion of the two components. To demonstrate that Cu-W structures are able to withstand the anticipated operating conditions, large Cu-W samples have been prepared by means of different techniques. Samples have been studied before and after thermal cycling (10 4 cycles). (author)

Mechanical characterization and modeling of brazed tungsten and Cu-Cr-Zr alloy using stress relief interlayers

Science.gov (United States)

Qu, Dandan; Zhou, Zhangjian; Yum, Youngjin; Aktaa, Jarir

2014-12-01

A rapidly solidified foil-type Ti-Zr based amorphous filler with a melting temperature of 850 °C was used to braze tungsten to Cu-Cr-Zr alloy for water cooled divertors and plasma facing components application. Brazed joints of dissimilar materials suffer from a mismatch in coefficients of thermal expansion. In order to release the residual stress caused by the mismatch, brazed joints of tungsten and Cu-Cr-Zr alloy using different interlayers were studied. The shear strength tests of brazed W/Cu joints show that the average strength of the joint with a W70Cu30 composite plate interlayer reached 119.8 MPa, and the average strength of the joint with oxygen free high conductivity copper (OFHC Cu)/Mo multi-interlayers reached 140.8 MPa, while the joint without interlayer was only 16.6 MPa. Finite element method (FEM) has been performed to investigate the stress distribution and effect of stress relief interlayers. FEM results show that the maximum von Mises stress occurs in the tungsten/filler interface and that the filler suffers the peak residual stresses and becomes the weakest zone. And the use of OFHC Cu/Mo multi-interlayers can reduce the residual stress significantly, which agrees with the mechanical experiment data.

Mechanical characterization and modeling of brazed tungsten and Cu–Cr–Zr alloy using stress relief interlayers

Energy Technology Data Exchange (ETDEWEB)

Qu, Dandan, E-mail: dandan.qu@partner.kit.edu [School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Zhou, Zhangjian, E-mail: zhouzhangjianustb@163.com [School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Yum, Youngjin [School of Mechanical Engineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Aktaa, Jarir [Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2014-12-15

A rapidly solidified foil-type Ti–Zr based amorphous filler with a melting temperature of 850 °C was used to braze tungsten to Cu–Cr–Zr alloy for water cooled divertors and plasma facing components application. Brazed joints of dissimilar materials suffer from a mismatch in coefficients of thermal expansion. In order to release the residual stress caused by the mismatch, brazed joints of tungsten and Cu–Cr–Zr alloy using different interlayers were studied. The shear strength tests of brazed W/Cu joints show that the average strength of the joint with a W70Cu30 composite plate interlayer reached 119.8 MPa, and the average strength of the joint with oxygen free high conductivity copper (OFHC Cu)/Mo multi-interlayers reached 140.8 MPa, while the joint without interlayer was only 16.6 MPa. Finite element method (FEM) has been performed to investigate the stress distribution and effect of stress relief interlayers. FEM results show that the maximum von Mises stress occurs in the tungsten/filler interface and that the filler suffers the peak residual stresses and becomes the weakest zone. And the use of OFHC Cu/Mo multi-interlayers can reduce the residual stress significantly, which agrees with the mechanical experiment data.

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

Ultrathin nickel hydroxide on carbon coated 3D-porous copper structures for high performance supercapacitors.

Science.gov (United States)

Kang, Kyeong-Nam; Kim, Ik-Hee; Ramadoss, Ananthakumar; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2018-01-03

An ultrathin nickel hydroxide layer electrodeposited on a carbon-coated three-dimensional porous copper structure (3D-C/Cu) is suggested as an additive and binder-free conductive electrode with short electron path distances, large electrochemical active sites, and improved structural stability, for high performance supercapacitors. The 3D-porous copper structure (3D-Cu) provides high electrical conductivity and facilitates electron transport between the Ni(OH) 2 active materials and the current collector of the Ni-plate. A carbon coating was applied to the 3D-Cu to prevent the oxidation of Cu, without degrading the electron transport behavior of the 3D-Cu. The 3D-Ni(OH) 2 /C/Cu exhibited a high specific capacitance of 1860 F g -1 at 1 A g -1 , and good cycling performance, with an 86.5% capacitance retention after 10 000 cycles. When tested in a two-electrode system, an asymmetric supercapacitor exhibited an energy density of 147.9 W h kg -1 and a power density of 37.0 kW kg -1 . These results open a new area of ultrahigh-performance supercapacitors, supported by 3D-Cu electrodes.

High-resolution electron-energy-loss spectroscopy studies of clean and hydrogen-covered tungsten (100) surfaces

International Nuclear Information System (INIS)

Woods, J.P.

1986-01-01

High-resolution (10-meV FWHM) low-energy (≤ 100eV) electrons are scattered from the tungsten (100) surface. Electron-energy-loss spectroscopy (EELS) selection rules are utilized to identify vibrational modes of the surface tungsten atoms. A 36-meV mode is measured on the c(2 X 2) thermally reconstructed surface and is modeled as an overtone of the 18-meV mode at M in the surface Brillouin zone. The superstructure of the reconstructed surface allows this mode to be observed in specular scattering. The surface tungsten atoms return to their bulk lateral positions with saturated hydrogen (β 1 phase) adsorption; and a 26-meV mode identified is due to the perpendicular vibration of the surface tungsten layers. The clean-room temperature surface does not display either low-energy vibrations and the surface is modeled as disordered. The three β 1 phase hydrogen vibrations are observed and a new vibration at 118 meV is identified. The 118-meV cross section displays characteristics of a parallel mode, but calculations show this assignment to be erroneous. There are two hydrogen atoms for each surface tungsten atom in the β 1 phase, and lattice-dynamical calculations show that the 118-meV mode is due to a hydrogen-zone edge vibration. The predicted breakdown of the parallel hydrogen vibration selection rule was not observed

Deuterium-induced nanostructure formation on tungsten exposed to high-flux plasma

NARCIS (Netherlands)

Xu, H.Y.; De Temmerman, G.; Luo, G. N.; Jia, Y. Z.; Yuan, Y.; Fu, B. Q.; Godfrey, A.; Liu, W.

2015-01-01

Surface topography of polycrystalline tungsten (W) have been examined after exposure to a low-energy (38 eV/D), high-flux (∼1.1–1.5 × 1024 m−2 s−1) deuterium plasma in the Pilot-PSI linear plasma device. The methods used were scanning electron microscopy

Effect of metallic coating on the properties of copper-silicon carbide composites

Science.gov (United States)

Chmielewski, M.; Pietrzak, K.; Teodorczyk, M.; Nosewicz, S.; Jarząbek, D.; Zybała, R.; Bazarnik, P.; Lewandowska, M.; Strojny-Nędza, A.

2017-11-01

In the presented paper a coating of SiC particles with a metallic layer was used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950 °C was provided. The almost fully dense materials were obtained (>97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

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.

Development and qualification of a bulk tungsten divertor row for JET

Science.gov (United States)

Mertens, Ph.; Altmann, H.; Hirai, T.; Philipps, V.; Pintsuk, G.; Rapp, J.; Riccardo, V.; Schweer, B.; Uytdenhouwen, I.; Samm, U.

2009-06-01

A bulk tungsten divertor row has been developed in the frame of the ITER-like Wall project at JET. It consists of 96 tiles grouped in 48 modules around the torus. The outer strike point is located on those tiles for most of the ITER-relevant, high triangularity plasmas. High power loads (locally up to 10-20 MW/m 2) and erosion rates are expected, even a risk of melting, especially with the transients or ELM loads. These are demanding conditions for an inertially cooled design as prescribed. A lamella design has been selected for the tungsten, arranged to control the eddy and halo current flows. The lamellae must also withstand high temperature gradients (2200 to 220 °C over 40 mm height), without overheating the supporting carrier (600-700 °C maximum). As a consequence of the tungsten emissivity, the radiative cooling drops appreciably in comparison with the current CFC tiles, calling for interleaved plasma scenarios in terms of performance. The compromise between shadowing and power handling is discussed, as well as the consequences for operation. Prototypes have been exposed in TEXTOR and in an electron beam facility (JUDITH-2) to the nominal power density of 7 MW/m 2 for 10 s and, in addition, to higher loads leading to surface temperatures above 2000 °C.

Modelling deuterium release from tungsten after high flux high temperature deuterium plasma exposure

Energy Technology Data Exchange (ETDEWEB)

Grigorev, Petr, E-mail: grigorievpit@gmail.com [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400 (Belgium); Ghent University, Applied Physics EA17 FUSION-DC, St. Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Department of Experimental Nuclear Physics K-89, Institute of Physics, Nanotechnologies, and Telecommunications, Peter the Great St. Petersburg Polytechnic University, St. Petersburg (Russian Federation); Matveev, Dmitry [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, Trilateral Euregio Cluster, 52425, Jülich (Germany); Bakaeva, Anastasiia [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400 (Belgium); Department of Applied Physics, Ghent University (Belgium); Terentyev, Dmitry [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400 (Belgium); Zhurkin, Evgeny E. [Department of Experimental Nuclear Physics K-89, Institute of Physics, Nanotechnologies, and Telecommunications, Peter the Great St. Petersburg Polytechnic University, St. Petersburg (Russian Federation); Van Oost, Guido [Ghent University, Applied Physics EA17 FUSION-DC, St. Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Noterdaeme, Jean-Marie [Ghent University, Applied Physics EA17 FUSION-DC, St. Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Max-Planck-Institut für Plasmaphysik, Garching (Germany)

2016-12-01

Tungsten is a primary candidate for plasma facing materials for future fusion devices. An important safety concern in the design of plasma facing components is the retention of hydrogen isotopes. Available experimental data is vast and scattered, and a consistent physical model of retention of hydrogen isotopes in tungsten is still missing. In this work we propose a model of non-equilibrium hydrogen isotopes trapping under fusion relevant plasma exposure conditions. The model is coupled to a diffusion-trapping simulation tool and is used to interpret recent experiments involving high plasma flux exposures. From the computational analysis performed, it is concluded that high flux high temperature exposures (T = 1000 K, flux = 10{sup 24} D/m{sup 2}/s and fluence of 10{sup 26} D/m{sup 2}) result in generation of sub-surface damage and bulk diffusion, so that the retention is driven by both sub-surface plasma-induced defects (bubbles) and trapping at natural defects. On the basis of the non-equilibrium trapping model we have estimated the amount of H stored in the sub-surface region to be ∼10{sup −5} at{sup −1}, while the bulk retention is about 4 × 10{sup −7} at{sup −1}, calculated by assuming the sub-surface layer thickness of about 10 μm and adjusting the trap concentration to comply with the experimental results for the integral retention.

Direct patterning of highly-conductive graphene@copper composites using copper naphthenate as a resist for graphene device applications.

Science.gov (United States)

Bi, Kaixi; Xiang, Quan; Chen, Yiqin; Shi, Huimin; Li, Zhiqin; Lin, Jun; Zhang, Yongzhe; Wan, Qiang; Zhang, Guanhua; Qin, Shiqiao; Zhang, Xueao; Duan, Huigao

2017-11-09

We report an electron-beam lithography process to directly fabricate graphene@copper composite patterns without involving metal deposition, lift-off and etching processes using copper naphthenate as a high-resolution negative-tone resist. As a commonly used industrial painting product, copper naphthenate is extremely cheap with a long shelf time but demonstrates an unexpected patterning resolution better than 10 nm. With appropriate annealing under a hydrogen atmosphere, the produced graphene@copper composite patterns show high conductivity of ∼400 S cm -1 . X-ray diffraction, conformal Raman spectroscopy and X-ray photoelectron spectroscopy were used to analyze the chemical composition of the final patterns. With the properties of high resolution and high conductivity, the patterned graphene@copper composites could be used as conductive pads and interconnects for graphene electronic devices with ohmic contacts. Compared to common fabrication processes involving metal evaporation and lift-off steps, this pattern-transfer-free fabrication process using copper naphthenate resist is direct and simple but allows comparable device performance in practical device applications.

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.)

Influence of copper high-tension lines on plants and soils

Energy Technology Data Exchange (ETDEWEB)

Kraal, H.; Ernst, W.

1976-09-01

The copper contents of plants and soils were determined in relation to the distance from copper high-tension lines. In the vicinity of the cables clayey and fenny soils had demonstrably higher copper contents, due to corrosion of the cables, than regions 20 m and more outside the high-tension lines. On these soils, however, copper accumulation in the plants was low in comparison with those from a sandy soil, although this soil itself showed no copper increase in relation to the cables. The contaminated plants may present a risk of poisoning for sheep within a 20 m distance on both sides of the cables. No changes in plant species composition and in the copper tolerance of Agrostis tenuis were observed.

High Power Density Motors

Science.gov (United States)

Kascak, Daniel J.

2004-01-01

With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

Detection of an electron beam in a high density plasma via an electrostatic probe

Science.gov (United States)

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart; Yamada, Masaaki; Ji, Hantao

2017-10-01

The perturbation in floating potential by an electron beam is detected by a 1D floating potential probe array to evaluate the use of an electron beam for magnetic field line mapping in the Magnetic Reconnection Experiment (MRX) plasma. The MRX plasma is relatively high density (1013 cm-3) and low temperature (5 eV). Beam electrons are emitted from a tungsten filament and are accelerated by a 200 V potential across the sheath. They stream along the magnetic field lines towards the probe array. The spatial electron beam density profile is assumed to be a Gaussian along the radial axis of MRX and the effective beam width is determined from the radial profile of the floating potential. The magnitude of the perturbation is in agreement with theoretical predictions and the location of the perturbation is also in agreement with field line mapping. In addition, no significant broadening of the electron beam is observed after propagation for tens of centimeters through the high density plasma. These results demonstrate that this method of field line mapping is, in principle, feasible in high density plasmas. This work is supported by the DOE Contract No. DE-AC0209CH11466.

Surface hardening induced by high flux plasma in tungsten revealed by nano-indentation

Energy Technology Data Exchange (ETDEWEB)

Terentyev, D., E-mail: dterenty@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium); Bakaeva, A. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, St. Pietersnieuwstraat 41, 9000 Ghent (Belgium); Pardoen, T.; Favache, A. [Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, Place Sainte Barbe 2 L5.02.02, 1348 Louvain-la-Neuve (Belgium); Zhurkin, E.E. [Department of Experimental Nuclear Physics K-89, Faculty of Physics and Mechanics, St. Petersburg State Polytechnical University, 29 Polytekhnicheskaya str., 195251 St. Petersburg (Russian Federation)

2016-08-01

Surface hardness of tungsten after high flux deuterium plasma exposure has been characterized by nanoindentation. The effect of plasma exposure was rationalized on the basis of available theoretical models. Resistance to plastic penetration is enhanced within the 100 nm sub-surface region, attributed to the pinning of geometrically necessary dislocations on nanometric deuterium cavities – signature of plasma-induced defects and deuterium retention. Sub-surface extension of thereby registered plasma-induced damage is in excellent agreement with the results of alternative measurements. The study demonstrates suitability of nano-indentation to probe the impact of deposition of plasma-induced defects in tungsten on near surface plasticity under ITER-relevant plasma exposure conditions.

Spectroscopy of highly charged tungsten ions with Electron Beam Ion Traps

International Nuclear Information System (INIS)

Sakaue, Hiroyuki A.; Kato, Daiji; Morita, Shigeru; Murakami, Izumi; Yamamoto, Norimasa; Ohashi, Hayato; Yatsurugi, Junji; Nakamura, Nobuyuki

2013-01-01

We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra is investigated of electron energies from 490 to 1440 eV. Previously unreported lines are presented in the EUV range, and some of them are identified by comparing the wavelengths with theoretical calculations. (author)

Radiative Recombination and Photoionization Data for Tungsten Ions. Electron Structure of Ions in Plasmas

Directory of Open Access Journals (Sweden)

Malvina B. Trzhaskovskaya

2015-05-01

Full Text Available Theoretical studies of tungsten ions in plasmas are presented. New calculations of the radiative recombination and photoionization cross-sections, as well as radiative recombination and radiated power loss rate coefficients have been performed for 54 tungsten ions for the range W6+–W71+. The data are of importance for fusion investigations at the reactor ITER, as well as devices ASDEX Upgrade and EBIT. Calculations are fully relativistic. Electron wave functions are found by the Dirac–Fock method with proper consideration of the electron exchange. All significant multipoles of the radiative field are taken into account. The radiative recombination rates and the radiated power loss rates are determined provided the continuum electron velocity is described by the relativistic Maxwell–Jüttner distribution. The impact of the core electron polarization on the radiative recombination cross-section is estimated for the Ne-like iron ion and for highly-charged tungsten ions within an analytical approximation using the Dirac–Fock electron wave functions. The effect is shown to enhance the radiative recombination cross-sections by ≲20%. The enhancement depends on the photon energy, the principal quantum number of polarized shells and the ion charge. The influence of plasma temperature and density on the electron structure of ions in local thermodynamic equilibrium plasmas is investigated. Results for the iron and uranium ions in dense plasmas are in good agreement with previous calculations. New calculations were performed for the tungsten ion in dense plasmas on the basis of the average-atom model, as well as for the impurity tungsten ion in fusion plasmas using the non-linear self-consistent field screening model. The temperature and density dependence of the ion charge, level energies and populations are considered.

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.

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

Suppression of tungsten accumulation during ELMy H-mode by lower hybrid wave heating in the EAST tokamak

Directory of Open Access Journals (Sweden)

L. Zhang

2017-08-01

Full Text Available EAST tokamak has been equipped with upper tungsten divertor since 2014. The tungsten accumulation has been often observed in NBI-heated H-mode discharges suggesting deleterious tungsten confinement in the plasma core. It causes not only H-L back transition but also plasma disruption in several discharges. Suppression of the tungsten accumulation is therefore the most important issue in EAST to achieve a long pulse H-mode discharge. In order to study the tungsten behavior in the long pulse discharge, tungsten spectra have been measured at 20–140Å. The tungsten density, nw, is evaluated from the intensity of tungsten unresolved transition array (W-UTA in a wavelength range of 45–70Å which is composed of several ionization stages of tungsten, e.g. W27+-W45+ at Te0∼2.5keV. It is found that the tungsten accumulation can be suppressed when the 4.6GHz LHW with PLHW∼0.8MW is superimposed on the NBI phase (PNBI= 1.9MW. During the superimposed phase the ELM frequency, fELM, increases from ∼30Hz to ∼60Hz and the tungsten density is halved compared to the NBI-heated discharge. The H-mode discharge can be thus steadily sustained for longer period. It is found that the nw is a large function of the ratio of LHW power to the total injection power, PLHW/(PLHW+PNBI, and the nw can be reduced, at least, in an order of magnitude smaller than that in NBI-heated discharges at PLHW/(PLHW+PNBI≥0.8. The result strongly suggests a possible way toward the steady H-mode discharge.

Fabrication and characterization of tungsten and graphite based PFC for divertor target elements of ITER like tokamak application

Energy Technology Data Exchange (ETDEWEB)

Khirwadkar, S.S., E-mail: sameer@ipr.res.in [Institute For Plasma Research, Bhat, Gandhinagar, Gujarat (India); Singh, K.P.; Patil, Y.; Khan, M.S.; Buch, J.J.U.; Patel, Alpesh; Tripathi, Sudhir [Institute For Plasma Research, Bhat, Gandhinagar, Gujarat (India); Jaman, P.M.; Rangaraj, L.; Divakar, C. [Materials Science Division, National Aerospace Laboratories, CSIR, Bangalore, Karnataka (India)

2011-10-15

The development of the fabrication technology of macro-brush configuration of tungsten (W) and carbon (graphite and CFC) plasma facing components (PFCs) for ITER like tokamak application is presented. The fabrication of qualified joint of PFC is a requirement for fusion tokamak. Vacuum brazing method has been employed for joining of W/CuCrZr and C/CuCrZr. Oxygen free high conductivity (OFHC) copper casting on W tiles was performed followed by machining, polishing and ultrasonic cleaning of the samples prior to vacuum brazing. The W/CuCrZr and graphite/CuCrZr based test mockups were vacuum brazed using silver free alloys. The mechanical shear and tensile strengths were evaluated for the W/CuCrZr and graphite/CuCrZr brazed joint samples. The micro-structural examination of the joints showed smooth interface. The details of fabrication and characterization procedure for macro-brush tungsten and carbon based PFC test mockups are presented.

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

Towards an all-copper redox flow battery based on a copper-containing ionic liquid.

Science.gov (United States)

Schaltin, Stijn; Li, Yun; Brooks, Neil R; Sniekers, Jeroen; Vankelecom, Ivo F J; Binnemans, Koen; Fransaer, Jan

2016-01-07

The first redox flow battery (RFB), based on the all-copper liquid metal salt [Cu(MeCN)4][Tf2N], is presented. Liquid metal salts (LMS) are a new type of ionic liquid that functions both as solvent and electrolyte. Non-aqueous electrolytes have advantages over water-based solutions, such as a larger electrochemical window and large thermal stability. The proof-of-concept is given that LMSs can be used as the electrolyte in RFBs. The main advantage of [Cu(MeCN)4][Tf2N] is the high copper concentration, and thus high charge and energy densities of 300 kC l(-1) and 75 W h l(-1) respectively, since the copper(i) ions form an integral part of the electrolyte. A Coulombic efficiency up to 85% could be reached.

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

Leaching of copper concentrates with high arsenic content in chlorine-chloride media

International Nuclear Information System (INIS)

Herreros, O.; Fuentes, G.; Quiroz, R.; Vinals, J.

2003-01-01

This work reports the results of copper concentrates leaching which have high arsenic concepts (up to 2.5%). The treatments were carried out using chlorine that forms from sodium hypochlorite and sulphuric acid. The aim of this work is to obtain a solution having high copper content 4 to 6 g/l and 5 to 7 g/l free acid in order to submit it directly to a solvent extraction stage. In addition, this solution should have minimum content of arsenic and chloride ions. To carry out this investigation, an acrylic reactor was constructed where the leaching tests were made at constant temperature in a thermostatic bath under atmospheric pressure. The concentrate samples were obtained from mineral processing plants from Antofagasta, Chile. Typical variables were studied, such as leaching agent concentration, leaching time, pulp density and temperature among others. Some of the residues were analyzed by XRD and EPS. On the other hand, the solutions were analyzed by Atomic Absorption Spectroscopy. The results indicate solutions having the contents stated above can be obtained. (Author) 19 refs

States of high energy density

International Nuclear Information System (INIS)

Murray, M.

1988-02-01

The transverse energy, E/sub tau/ spectra for O 16 and S 32 incident for various elements at 200 GeVnucleon are shown. The target and projectile dependencies of the data are discussed. The energy density achieved is estimated. For O 16 on Tungsten the multiplicity spectrum is also presented as well as the pseudorapidity spectra as a function of the transverse energy. The multiplicity cross section dσdN as measured in the backward hemisphere (0.9 < /eta/ < 2.9/ is found to be very similar in shape to the transverse energy distribution dσdE/tau/ reflecting the particular geometry of nucleus nucleus nucleus collisions. The dependence on the atomic mass of the target, A/sub tau/ and projectile A/sub p/ is not what one would expect from naive considerations

Thermal stability of a highly-deformed warm-rolled tungsten plate in the temperature range 1100–1250 °C

Energy Technology Data Exchange (ETDEWEB)

Alfonso, A., E-mail: aalz@dtu.dk [Section of Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Juul Jensen, D. [Danish-Chinese Center for Nanometals, Section of Materials Science and Advanced Characterization, Department of Wind Energy, Technical University of Denmark, Risø Campus, 4000 Roskilde (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Luo, G.-N. [Fusion Reactor Materials Science and Technology Division, Institute of Plasma Physics, Chinese Academy of Sciences, 230031 Hefei, Anhui (China); Sino-Danish Center for Education and Research, Denmark and China (Denmark); Pantleon, W. [Section of Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Association EURATOM-DTU (Denmark); Sino-Danish Center for Education and Research, Denmark and China (Denmark)

2015-10-15

Highlights: • Annealing kinetics of highly-deformed tungsten up to 190 h between 1100 °C and 1250 °C. • Loss of mechanical strength characterized by Vickers hardness measurements. • Two distinct stages of recovery and recrystallization identified and described by established models. • Activation energy of recrystallization lower than after moderate deformation of tungsten. • Comparable to activation energy of grain boundary diffusion due to abundance of low angle boundaries. - Abstract: Pure tungsten is considered as armor material for the most critical parts of fusion reactors (i.e. the divertor and the first wall), among other reasons due to its high melting point (3422 °C) and recrystallization temperature. The thermal stability of a pure tungsten plate warm-rolled to a high plastic strain by 90% thickness reduction was investigated by isothermal annealing for up to 190 h in the temperature range between 1100 °C and 1250 °C. Vickers hardness testing allowed tracking the changes in mechanical properties caused by recovery and recrystallization. The hardness evolution could be rationalized in terms of a logarithmic recovery kinetics and a Johnson–Mehl–Avrami–Kolmogorov recrystallization kinetics accounting for an incubation time of recrystallization. The observed time spans for recrystallization and the corresponding recrystallization activation energy for this highly deformed plate suggest that large plastic deformations (e.g. applied during shaping) are only suitable to produce tungsten components to be used at relatively low temperatures (up to 900 °C for a 2 years lifespan). Higher operation temperatures will lead to fast degradation of the microstructure during operation.

Thermal stability of a highly-deformed warm-rolled tungsten plate in the temperature range 1100–1250 °C

International Nuclear Information System (INIS)

Alfonso, A.; Juul Jensen, D.; Luo, G.-N.; Pantleon, W.

2015-01-01

Highlights: • Annealing kinetics of highly-deformed tungsten up to 190 h between 1100 °C and 1250 °C. • Loss of mechanical strength characterized by Vickers hardness measurements. • Two distinct stages of recovery and recrystallization identified and described by established models. • Activation energy of recrystallization lower than after moderate deformation of tungsten. • Comparable to activation energy of grain boundary diffusion due to abundance of low angle boundaries. - Abstract: Pure tungsten is considered as armor material for the most critical parts of fusion reactors (i.e. the divertor and the first wall), among other reasons due to its high melting point (3422 °C) and recrystallization temperature. The thermal stability of a pure tungsten plate warm-rolled to a high plastic strain by 90% thickness reduction was investigated by isothermal annealing for up to 190 h in the temperature range between 1100 °C and 1250 °C. Vickers hardness testing allowed tracking the changes in mechanical properties caused by recovery and recrystallization. The hardness evolution could be rationalized in terms of a logarithmic recovery kinetics and a Johnson–Mehl–Avrami–Kolmogorov recrystallization kinetics accounting for an incubation time of recrystallization. The observed time spans for recrystallization and the corresponding recrystallization activation energy for this highly deformed plate suggest that large plastic deformations (e.g. applied during shaping) are only suitable to produce tungsten components to be used at relatively low temperatures (up to 900 °C for a 2 years lifespan). Higher operation temperatures will lead to fast degradation of the microstructure during operation.

Results of high heat flux tests and structural analysis of the new solid tungsten divertor tile for ASDEX Upgrade

Energy Technology Data Exchange (ETDEWEB)

Jaksic, Nikola, E-mail: nikola.jaksic@ipp.mpg.de; Greuner, Henri; Herrmann, Albrecht; Böswirth, Bernd; Vorbrugg, Stefan

2015-10-15

Highlights: • The main motivation for the HHF investigation of tungsten tiles was an untypical deformation of some specimens under thermal loading, observed during the previous tests in GLADIS test facility. • A nonlinear finite element (FE) model for simulations of the GLADIS tests has been built. • The unexpected plastic deformations are mainly caused by internal stresses due to the manufacturing process. The small discrepancies among the FEA investigated and measured plastic deformations are most likely caused, beside of the practical difficulties by measuring of low items, also by tile internal stresses. • The influences of the residual stresses caused by special production processes have to be taken into account by design of the structural part made of solid tungsten. - Abstract: Tungsten as plasma-facing material for fusion devices is currently the most favorable candidate. In general solid tungsten is used for shielding the plasma chamber interior against the high heat generated from the plasma. For the purposes of implementation at ASDEX Upgrade and as a contribution to ITER the thermal performance of tungsten tiles has been extensively tested in the high heat flux test facility GLADIS during the development phase and beyond. These tests have been performed on full scale tungsten tile prototypes including their clamping and cooling structure. Simulating the adiabatically thermal loading due to plasma operation in ASDEX Upgrade, the tungsten tiles have been subjected to a thermal load with central heat flux of 10–24 MW/m{sup 2} and absorbed energy between 370 and 680 kJ. This loading results in maximum surface temperatures between 1300 °C and 2800 °C. The tests in GLADIS have been accompanied by intensive numerical investigations using FEA methods. For this purpose a multiple nonlinear finite element model has been set up. This paper discusses the main results of the high heat flux final tests and their numerical simulation. Moreover, first

Results of high heat flux tests and structural analysis of the new solid tungsten divertor tile for ASDEX Upgrade

International Nuclear Information System (INIS)

Jaksic, Nikola; Greuner, Henri; Herrmann, Albrecht; Böswirth, Bernd; Vorbrugg, Stefan

2015-01-01

Highlights: • The main motivation for the HHF investigation of tungsten tiles was an untypical deformation of some specimens under thermal loading, observed during the previous tests in GLADIS test facility. • A nonlinear finite element (FE) model for simulations of the GLADIS tests has been built. • The unexpected plastic deformations are mainly caused by internal stresses due to the manufacturing process. The small discrepancies among the FEA investigated and measured plastic deformations are most likely caused, beside of the practical difficulties by measuring of low items, also by tile internal stresses. • The influences of the residual stresses caused by special production processes have to be taken into account by design of the structural part made of solid tungsten. - Abstract: Tungsten as plasma-facing material for fusion devices is currently the most favorable candidate. In general solid tungsten is used for shielding the plasma chamber interior against the high heat generated from the plasma. For the purposes of implementation at ASDEX Upgrade and as a contribution to ITER the thermal performance of tungsten tiles has been extensively tested in the high heat flux test facility GLADIS during the development phase and beyond. These tests have been performed on full scale tungsten tile prototypes including their clamping and cooling structure. Simulating the adiabatically thermal loading due to plasma operation in ASDEX Upgrade, the tungsten tiles have been subjected to a thermal load with central heat flux of 10–24 MW/m"2 and absorbed energy between 370 and 680 kJ. This loading results in maximum surface temperatures between 1300 °C and 2800 °C. The tests in GLADIS have been accompanied by intensive numerical investigations using FEA methods. For this purpose a multiple nonlinear finite element model has been set up. This paper discusses the main results of the high heat flux final tests and their numerical simulation. Moreover, first results

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

Effects of current density and electrolyte temperature on the volume expansion factor of anodic alumina formed in oxalic acid

International Nuclear Information System (INIS)

Zhou, F.; Baron-Wiecheć, A.; Garcia-Vergara, S.J.; Curioni, M.; Habazaki, H.; Skeldon, P.; Thompson, G.E.

2012-01-01

The formation of porous anodic alumina in 0.4 M oxalic acid is investigated over a range of current density and electrolyte temperature using sputtering-deposited substrates containing tungsten tracer layers. The findings reveal volume expansion factors and efficiencies of film growth that increase with the increase of the current density and decrease of the temperature. Pore generation by the flow of the anodic alumina in the barrier layer toward the pore walls is proposed to dominate at relatively high current densities (above ∼2 mA cm −2 ), with tungsten tracer species being retained within films. Conversely, losses of tungsten species occur at lower current densities, possibly due to increased field-assisted ejection of Al 3+ ions and/or field-assisted dissolution of the anodic alumina.

Tungsten transport and sources control in JET ITER-like wall H-mode plasmas

Energy Technology Data Exchange (ETDEWEB)

Fedorczak, N., E-mail: nicolas.fedorczak@cea.fr [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Monier-Garbet, P. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Pütterich, T. [MPI für Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Brezinsek, S. [Institute of Energy and Climate Research, Forschungszentrum Jlich, Assoc EURATOM-FZJ, Jlich (Germany); Devynck, P.; Dumont, R.; Goniche, M.; Joffrin, E. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Lerche, E. [Association EURATOM-Belgian State, LPP-ERM-KMS, TEC partner, Brussels (Belgium); Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Lipschultz, B. [York Plasma Institute, University of York, Heslington, York YO10 5DD (United Kingdom); Luna, E. de la [Laboratorio Nacional de Fusin, Asociacin EURATOM/CIEMAT, 28040 Madrid (Spain); Maddison, G. [Culham Centre for Fusion Energy, EURATOM-CCFE Association, Abingdon (United Kingdom); Maggi, C. [MPI für Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, 85748 Garching (Germany); Matthews, G. [Culham Centre for Fusion Energy, EURATOM-CCFE Association, Abingdon (United Kingdom); Nunes, I. [Istituto de plasmas e fusao nuclear, Lisboa (Portugal); Rimini, F. [Culham Centre for Fusion Energy, EURATOM-CCFE Association, Abingdon (United Kingdom); Solano, E.R. [Laboratorio Nacional de Fusin, Asociacin EURATOM/CIEMAT, 28040 Madrid (Spain); Tamain, P. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Tsalas, M. [Association EURATOM-Hellenic Republic, NCSR Demokritos 153 10, Attica (Greece); Vries, P. de [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

2015-08-15

A set of discharges performed with the JET ITER-like wall is investigated with respect to control capabilities on tungsten sources and transport. In attached divertor regimes, increasing fueling by gas puff results in higher divertor recycling ion flux, lower divertor tungsten source, higher ELM frequency and lower core plasma radiation, dominated by tungsten ions. Both pedestal flushing by ELMs and divertor screening (including redeposition) are possibly responsible. For specific scenarios, kicks in plasma vertical position can be employed to increase the ELM frequency, which results in slightly lower core radiation. The application of ion cyclotron radio frequency heating at the very center of the plasma is efficient to increase the core electron temperature gradient and flatten electron density profile, resulting in a significantly lower central tungsten peaking. Beryllium evaporation in the main chamber did not reduce the local divertor tungsten source whereas core radiation was reduced by approximately 50%.

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

Chemical and microstructural changes at high temperature in tungsten wire reinforced metal-matrix composite materials

International Nuclear Information System (INIS)

Eaton, H.C.; Norden, H.

1985-01-01

Tungsten wire reinforced metal-matrix composites have been developed as a gas turbine blade material. Initially it was thought desirable to employ nickel or iron based superalloys as the matrix material due to their demonstrated reliability in applications where a high degree of dimensional stability, and thermal and mechanical fatigue resistance are required. It has been found, however, that deleterious fiber/matrix interactions occur in these systems under in-service conditions. These interactions seriously degrade the mechanical properties, and there is an effective lowering of the recrystallization temperature of the tungsten to the degree that grain structure changes can take place at unusually low temperatures. The present communication reports a study of the early stages of these interactions. Several microscopic and analytical techniques are used: TEM, SIMS, FIM, and the field ion atom probe. The nickel/tungsten interaction is thought to involve solute atom transport along grain boundaries. The grain boundary chemistry after short exposures to nickel at 1100 0 C is determined. In this manner the precursor interaction mechanisms are observed. These observations suggest that the strong nickel/tungsten grain boundary interactions do not involve the formation of distinct alloy phases, but instead involve rapid diffusion of essentially unalloyed nickel along the grain boundaries

Development of highly faceted reduced graphene oxide-coated copper oxide and copper nanoparticles on a copper foil surface

Directory of Open Access Journals (Sweden)

Rebeca Ortega-Amaya

2016-07-01

Full Text Available This work describes the formation of reduced graphene oxide-coated copper oxide and copper nanoparticles (rGO-Cu2ONPs, rGO-CuNPs on the surface of a copper foil supporting graphene oxide (GO at annealing temperatures of 200–1000 °C, under an Ar atmosphere. These hybrid nanostructures were developed from bare copper oxide nanoparticles which grew at an annealing temperature of 80 °C under nitrogen flux. The predominant phase as well as the particle size and shape strongly depend on the process temperature. Characterization with transmission electron microscopy and scanning electron microscopy indicates that Cu or Cu2O nanoparticles take rGO sheets from the rGO network to form core–shell Cu–rGO or Cu2O–rGO nanostructures. It is noted that such ones increase in size from 5 to 800 nm as the annealing temperature increases in the 200–1000 °C range. At 1000 °C, Cu nanoparticles develop a highly faceted morphology, displaying arm-like carbon nanorods that originate from different facets of the copper crystal structure.

Oxidation-assisted graphene heteroepitaxy on copper foil.

Science.gov (United States)

Reckinger, Nicolas; Tang, Xiaohui; Joucken, Frédéric; Lajaunie, Luc; Arenal, Raul; Dubois, Emmanuel; Hackens, Benoît; Henrard, Luc; Colomer, Jean-François

2016-11-10

We propose an innovative, easy-to-implement approach to synthesize aligned large-area single-crystalline graphene flakes by chemical vapor deposition on copper foil. This method doubly takes advantage of residual oxygen present in the gas phase. First, by slightly oxidizing the copper surface, we induce grain boundary pinning in copper and, in consequence, the freezing of the thermal recrystallization process. Subsequent reduction of copper under hydrogen suddenly unlocks the delayed reconstruction, favoring the growth of centimeter-sized copper (111) grains through the mechanism of abnormal grain growth. Second, the oxidation of the copper surface also drastically reduces the nucleation density of graphene. This oxidation/reduction sequence leads to the synthesis of aligned millimeter-sized monolayer graphene domains in epitaxial registry with copper (111). The as-grown graphene flakes are demonstrated to be both single-crystalline and of high quality.

In situ oxide dispersion strengthened tungsten alloys with high compressive strength and high strain-to-failure

International Nuclear Information System (INIS)

Huang, Lin; Jiang, Lin; Topping, Troy D.; Dai, Chen; Wang, Xin; Carpenter, Ryan; Haines, Christopher; Schoenung, Julie M.

2017-01-01

In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10"−"4 s"−"1) and strain-to-failure (over 40%) of bulk tungsten materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS). The results show that the application of a high pressure of 1 GPa during SPS significantly accelerates the densification process. Concurrently, the second phase oxide nanoparticles with an average grain size of 108 nm, which are distributed within the interiors of the W grains, simultaneously provide strengthening and plasticity by inhibiting grain growth, and generating, blocking, and storing dislocations. - Graphical abstract: In this work a novel process methodology to concurrently improve the compressive strength (2078 MPa at a strain rate of 5 × 10"−"4 s"−"1) and strain-to-failure (over 40%) of bulk W materials has been described. The process involves the in situ formation of intragranular tungsten oxide nanoparticles, facilitated by the application of a pressure of 1 GPa at a low sintering temperature of 1200 °C during spark plasma sintering (SPS).

EUV spectrum of highly charged tungsten ions in electron beam ion trap

International Nuclear Information System (INIS)

Sakaue, H.A.; Kato, D.; Murakami, I.; Nakamura, N.

2016-01-01

We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra was investigated for electron energy from 540 to 1370 eV. Previously unreported lines were presented in the EUV range, and comparing the wavelengths with theoretical calculations identified them. (author)

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

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

Brazing molybdenum and tungsten for high temperature service

International Nuclear Information System (INIS)

Lundberg, L.B.; Turner, W.C.; Hoffman, C.G.

1978-01-01

Investigations were conducted to develop vacuum brazes for molybdenum and tungsten which can be used in seal joint applications up to 1870 K (1597 C, 2907 F). Joints were attempted in molybdenum, tungsten and tungsten--molybdenum. The braze materials included: Ti--10Cr powder, Ti--30V wire, Ti--65V wire, V wire, Ni electroplate, MoB--50MoC powder mixture, V--50Mo powder mixture, Mo--15MoB 2 powder mixture and Mo--49V--15MoB 2 powder mixture. Braze temperature ranged from 1900 K (1627 C, 2961 F) to 2530 K, (2257 C, 4095 F), and leak-tight joints were made with all braze materials except Ti--10Cr. After heat treatments up to 1870 K (1597 C, 2907 F) Kirkendall voiding was found to cause leakage of some of the joints made with only substitutional alloying elements. However, adding base metal powders to the braze or narrowing the root opening eliminated this problem. Kirkendall voiding was not a problem when interstitial elements were a major ingredient in the braze material. Shear testing of Ti--65V, V, MoB--50MoC and V--50Mo brazed molybdenum at 1670 K (1397 C, 2547 F) indicated strengths equal to or better than the base metal. Ti--65V, V--50Mo and MoB--50MoC brazed joints were exposed to basalt at 1670 K (1397 C, 2547 F) for 3 h without developing leaks

Plasma interaction with tungsten samples in the COMPASS tokamak in ohmic ELMy H-modes

International Nuclear Information System (INIS)

Dimitrova, M; Weinzettl, V; Matejicek, J; Dejarnac, R; Stöckel, J; Havlicek, J; Panek, R; Popov, Tsv; Marinov, S; Costea, S

2016-01-01

This paper reports experimental results on plasma interaction with tungsten samples with or without pre-grown He fuzz. Under the experimental conditions, arcing was observed on the fuzzy tungsten samples, resulting in localized melting of the fuzz structure that did not extend into the bulk. The parallel power flux densities were obtained from the data measured by Langmuir probes embedded in the divertor tiles on the COMPASS tokamak. Measurements of the current-voltage probe characteristics were performed during ohmic ELMy H-modes reached in deuterium plasmas at a toroidal magnetic field B T = 1.15 T, plasma current I p = 300 kA and line-averaged electron density n e = 5×10 19 m -3 . The data obtained between the ELMs were processed by the recently published first-derivative probe technique for precise determination of the plasma potential and the electron energy distribution function (EEDF). The spatial profile of the EEDF shows that at the high-field side it is Maxwellian with a temperature of 5 -- 10 eV. The electron temperatures and the ion-saturation current density obtained were used to evaluate the radial distribution of the parallel power flux density as being in the order of 0.05 -- 7 MW/m 2 . (paper)

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)

Influence of surface morphology and microstructure on performance of CVD tungsten coating under fusion transient thermal loads

Energy Technology Data Exchange (ETDEWEB)

Lian, Youyun, E-mail: lianyy@swip.ac.cn [Southwestern Institute of Physics, Chengdu (China); Liu, Xiang; Wang, Jianbao; Feng, Fan [Southwestern Institute of Physics, Chengdu (China); Lv, Yanwei; Song, Jiupeng [China National R& D Center for Tungsten Technology, Xiamen Tungsten Co. Ltd, 361026 Xiamen (China); Chen, Jiming [Southwestern Institute of Physics, Chengdu (China)

2016-12-30

Highlights: • Thick CVD-W coatingswere deposited at a rapid growth rate. • The polished CVD-W coatings have highly textured structure and exhibited a very strong preferred orientation. • The polished CVD tungsten coatings show superior thermal shock resistance as compared with that of the as-deposited coatings. • The crack formation of the polished CVD-W was almost suppressed at an elevated temperature. - Abstract: Thick tungsten coatings have been deposited by chemical vapor deposition (CVD) at a rapid growth rate. A series of tungsten coatings with different thickness and surface morphology were prepared. The surface morphology, microstructure and preferred orientation of the CVD tungsten coatings were investigated. Thermal shock analyses were performed by using an electron beam facility to study the influence of the surface morphology and the microstructure on the thermal shock resistance of the CVD tungsten coatings. Repetitive (100 pulses) ELMs-like thermal shock loads were applied at various temperatures between room temperature and 600 °C with pulse duration of 1 ms and an absorbed power density of up to 1 GW/m{sup 2}. The results of the tests demonstrated that the specific surface morphology and columnar crystal structure of the CVD tungsten have significant influence on the surface cracking threshold and crack propagation of the materials. The CVD tungsten coatings with a polished surface show superior thermal shock resistance as compared with that of the as-deposited coatings with a rough surface.

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)

High-speed cinematography of gas-tungsten arc welding: theory and application

Energy Technology Data Exchange (ETDEWEB)

Reynolds, L.D.; Key, J.F.

1981-06-01

High-speed photo-instrumentation theory and application are reviewed, with particular emphasis on high-speed cinematography, for the engineer who has not acquired an extensive background in scientific photography. Camera systems, optics, timing system, lighting, photometric equipment, filters, and camera mounts are covered. Manufacturers and other resource material are listed in the Appendices. The properties and processing of photosensitive materials suitable for high-speed photography are reviewed, and selected film data are presented. Methods are described for both qualitative and quantitative film analysis. This technology is applied to the problem of analyzing plasma dynamics in a gas-tungsten welding arc.

Tungsten covered graphite and copper elements and ITER-like actively cooled tungsten divertor plasma facing units for the WEST project

International Nuclear Information System (INIS)

Guilhem, D; Bucalossi, J; Burles, S; Corre, Y; Ferlay, F; Firdaouss, M; Languille, P; Lipa, M; Martinez, A; Missirlian, M; Proust, M; Richou, M; Samaille, F; Tsitrone, E

2016-01-01

After a brief introduction giving some insight of the WEST project, we present the three types of plasma facing units (PFUs) developed for the WEST project taking into account the envisaged main scenarios: (1) high power short pulse scenario (a few seconds) where the objective is to maximize the power handling of the PFUs, up to 20 MW m −2 , (2) high fluence scenario (a few 100 s) on actively cooled ITER-like tungsten (W) PFUs, up to 10 MW m −2 during 1000 s. For the graphite PFUs, the high heat flux tests have been done at GLADIS (ion beam test facility), and for the CuCrZr PFUs on the JUDITH (electron beam test facility). The tests were successful, as no damage occurred for the different load cases. This confirms that the modelling done during the design phase is appropriate to describe these PFUs. Series productions are expected to be achieved by the end of 2015 for the graphite and CuCrZr PFUs, and few ITER-like W PFUs are expected at the beginning of 2016. The lower divertor will be complemented with ITER-like W PFUs as soon as available from our partners so that different fabrication procedures could be evaluated in a real industrial process and a real tokamak environment. (paper)

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.

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.

Copper wire theft and high voltage electrical burns

OpenAIRE

Francis, Eamon C; Shelley, Odhran P

2014-01-01

High voltage electrical burns are uncommon. However in the midst of our economic recession we are noticing an increasing number of these injuries. Copper wire is a valuable commodity with physical properties as an excellent conductor of electricity making it both ubiquitous in society and prized on the black market. We present two consecutive cases referred to the National Burns Unit who sustained life threatening injuries from the alleged theft of high voltage copper wire and its omnipresenc...

Analytical expressions for thermophysical properties of solid and liquid tungsten relevant for fusion applications

Directory of Open Access Journals (Sweden)

P. Tolias

2017-12-01

Full Text Available The status of the literature is reviewed for several thermophysical properties of pure solid and liquid tungsten which constitute input for the modelling of intense plasma-surface interaction phenomena that are important for fusion applications. Reliable experimental data are analyzed for the latent heat of fusion, the electrical resistivity, the specific isobaric heat capacity, the thermal conductivity and the mass density from the room temperature up to the boiling point of tungsten as well as for the surface tension and the dynamic viscosity across the liquid state. Analytical expressions of high accuracy are recommended for these thermophysical properties that involved a minimum degree of extrapolations. In particular, extrapolations were only required for the surface tension and viscosity.

Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries

Directory of Open Access Journals (Sweden)

Shim Hee-Sang

2011-01-01

Full Text Available Abstract We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoO x . The copper nanofibers (CuNFs were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoO x thin-film (CoO x TF electrodes, the CuNFs@CoO x electrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate. Such enhanced Li-ion storage performance may be associated with modified electrode structure at the nanoscale, improved charge transfer, and facile stress relaxation from the embedded CuNF network. Consequently, the CuNFs@CoO x composite structure demonstrated here can be used as a promising high-performance electrode for Li-ion batteries.

Laser-assisted nanostructuring of Tungsten in liquid environment

Energy Technology Data Exchange (ETDEWEB)

Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Stratakis, E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology, Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Materials Science and Technology Department, University of Crete, Heraklion 710 03 (Greece); Barberoglou, M. [Institute of Electronic Structure and Laser, Foundation for Research and Technology, Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Physics Department, University of Crete, Heraklion 714 09 (Greece); Stolyarov, V.N.; Stolyarov, I.N. [Roentgenprom, 35 Lenin str., Protvino, 1442281 Moscow region (Russian Federation); Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology, Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Physics Department, University of Crete, Heraklion 714 09 (Greece); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

2012-05-15

Formation of surface nanostructures on Tungsten target immersed into liquids is experimentally studied under its exposure to femtosecond laser pulses with different durations. In particular, nanotexturing of Tungsten upon its exposure to delayed femtosecond pulses is investigated. Two different types of morphological features are observed, namely periodic ripples and nanostructures. Field emission scanning electron microscopy shows that the density of nanostructures as well as their morphology depends on the time delay between pulses and reaches its maximum at 1 ps delay. Thermionic emission of nano-structured W cathode is investigated. The work function of nanostructured W surface is measured to be 0.3 eV lower than that of the pristine surface.

The origin of stress in sputter-deposited tungsten films for x-ray masks

International Nuclear Information System (INIS)

Itoh, M.; Hori, M.; Nadahara, S.

1991-01-01

The mechanism for the cause of stress in a sputter-deposited tungsten (W) film has been clarified. The tensile stress of the film was calculated using the interatomic forces acting on the grain boundary. The average distance of the grain boundary gaps was determined from the measured film density assuming the film had homogeneous size rectangular grains. The calculated and measured stress values were in good agreement in the high working gas pressure region. The difference between these values in the low working gas pressure region has been able to be explained by the compressive stress due to the peening effect of Ar. The low stress in the high pressure region was obtained by large opened grain boundaries which produced low film density. A low film density causes a low x-ray stopping power. The film deposited in the low pressure region is suitable as an x-ray absorber because of its high film density

The Time Structure of Hadronic Showers in Highly Granular Calorimeters with Tungsten and Steel Absorbers

CERN Document Server

Adloff, C.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S.T.; Sosebee, M.; White, A.P.; Yu, J.; Eigen, G.; Thomson, M.A.; Ward, D.R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, A.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Carloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch.; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D.H.; Kong, D.J.; Oh, Y.D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G.W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P.D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Ete, R.; Grenier, G.; Han, R.; Ianigro, J-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouene, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T.H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch.; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J.S.; Song, H.S.; Lee, S.H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

2014-01-01

The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

Peculiarity of deuterium ions interaction with tungsten surface in the condition imitating combination of normal operation with plasma disruption in ITER

Energy Technology Data Exchange (ETDEWEB)

Guseva, M.I. E-mail: martyn@nfi.kiae.ru; Vasiliev, V.I.; Gureev, V.M.; Danelyan, L.S.; Khirpunov, B.I.; Korshunov, S.N.; Kulikauskas, V.S.; Martynenko, Yu.V.; Petrov, V.B.; Strunnikov, V.N.; Stolyarova, V.G.; Zatekin, V.V.; Litnovsky, A.M

2001-03-01

Tungsten is a candidate material for the ITER divertor. For the simulation of ITER normal operation conditions in combination with plasma disruptions samples of various types of tungsten were exposed to both steady-state and high power pulsed deuterium plasmas. Tungsten samples were first exposed in a steady-state plasma with an ion current density {approx}10{sup 21} m{sup -2} s{sup -1} up to a dose of 10{sup 25} m{sup -2} at a temperature of 770 K. The energy of deuterium ions was 150 eV. The additional exposure of the samples to 10 pulses of deuterium plasma was performed in the electrodynamical plasma accelerator with an energy flux 0.45 MJ/m{sup 2} per pulse. Samples of four types of tungsten (W-1%La{sub 2}O{sub 3}, W-13I, monocrystalline W(1 1 1) and W-10%Re) were investigated. The least destruction of the surface was observed for W(1 1 1). The concentration of retained deuterium in tungsten decreased from 2.5x10{sup 19} m{sup -2} to 1.07x10{sup 19} m{sup -2} (for W(1 1 1)) as a result of the additional pulsed plasma irradiation. Investigation of the tungsten erosion products after the high power pulsed plasma shots was also carried out.

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.

Characterization of thermomechanical damage on tungsten surfaces during long-duration plasma transients

Energy Technology Data Exchange (ETDEWEB)

Rivera, David, E-mail: david.rivera.ucla@gmail.com; Crosby, Tamer; Sheng, Andrew; Ghoniem, Nasr M.

2014-12-15

A new experimental facility constructed at UCLA for the simulation of high heat flux effects on plasma-facing materials is described. The High Energy Flux Test Facility (HEFTY) is equipped with a Praxair model SG-100 plasma gun, which is nominally rated at 80 kW of continuous operation, of which approximately 30 kW reaches the target due to thermal losses. The gun is used to impart high intermittent heat flux to metal samples mounted within a cylindrical chamber. The system is capable of delivering an instantaneous heat flux in the range of 30–300 MW/m{sup 2}, depending on sample proximity to the gun. The duration of the plasma heat flux is in the range of 1–1000 s, making it ideal for studies of mild plasma transients of relatively long duration. Tungsten and tungsten-copper alloy metal samples are tested in these transient heat flux conditions, and the surface is characterized for damage evaluation using optical, SEM, XRD, and micro-fabrication techniques. Results from a Finite Element (FE) thermo-elastoplasticity model indicate that during the heat-up phase of a plasma transient pulse, the majority of the sample surface is under compressive stresses leading to plastic deformation of the surface. Upon sample cooling, the recovered elastic strain of cooler parts of the sample exceeds that from parts that deformed plastically, resulting in a tensile surface self-stress (residual surface stress). The intensity of the residual tensile surface stress is experimentally correlated with the onset of complex surface fracture morphology on the tungsten surface, and extending below the surface region. Micro-compression mechanical tests of W micro-pillars show that the material has significant plasticity, failing by a “barreling” mode before plasma exposure, and by normal dislocation slip and localized shear after plasma exposure. Ongoing modeling of the complex thermo-fracture process, coupled with elasto-plasticity is based on a phase field approach for distributed

Ultrafine tungsten as a plasma-facing component in fusion devices: effect of high flux, high fluence low energy helium irradiation

International Nuclear Information System (INIS)

El-Atwani, O.; Gonderman, Sean; Allain, J.P.; Efe, Mert; Klenosky, Daniel; Qiu, Tian; De Temmerman, Gregory; Morgan, Thomas; Bystrov, Kirill

2014-01-01

This work discusses the response of ultrafine-grained tungsten materials to high-flux, high-fluence, low energy pure He irradiation. Ultrafine-grained tungsten samples were exposed in the Pilot-PSI (Westerhout et al 2007 Phys. Scr. T128 18) linear plasma device at the Dutch Institute for Fundamental Energy Research (DIFFER) in Nieuwegein, the Netherlands. The He flux on the tungsten samples ranged from 1.0 × 10 23 –2.0 × 10 24  ions m −2  s −1 , the sample bias ranged from a negative (20–65) V, and the sample temperatures ranged from 600–1500 °C. SEM analysis of the exposed samples clearly shows that ultrafine-grained tungsten materials have a greater fluence threshold to the formation of fuzz by an order or magnitude or more, supporting the conjecture that grain boundaries play a major role in the mechanisms of radiation damage. Pre-fuzz damage analysis is addressed, as in the role of grain orientation on structure formation. Grains of (1 1 0) and (1 1 1) orientation showed only pore formation, while (0 0 1) oriented grains showed ripples (higher structures) decorated with pores. Blistering at the grain boundaries is also observed in this case. In situ TEM analysis during irradiation revealed facetted bubble formation at the grain boundaries likely responsible for blistering at this location. The results could have significant implications for future plasma-burning fusion devices given the He-induced damage could lead to macroscopic dust emission into the fusion plasma. (paper)

On the kinetics of high-temperature interaction of tungsten with light hydrocarbons

International Nuclear Information System (INIS)

Kharatyan, S.L.; Chatilyan, A.A.; Merzhanov, A.G.

1989-01-01

Comparative investigation of tungsten carbidizing treatment in ethylene, acetylene and methane media at T=1750-2500 deg C and p=2-10 Torr is carried out by the electrothermographical method. In all cases interaction is shown to proceed in stages due to step-by-step formation of carbide phases of tungsten W 2 C and WC as well as pyrocarbon. It is established that efficiency of carbidizing treatment is turned out to be maximum in methane medium in spite of great absolute values of ethylene and acetylene pyrolysis velocities on the surface of tungsten carbides in comparison with methane. Criterion of carburizing capability of hydrocarbous relatively to a metal is given on the basis of the results obtained

COPPER RESISTANT STRAIN CANDIDA TROPICALIS RomCu5 INTERACTION WITH SOLUBLE AND INSOLUBLE COPPER COMPOUNDS

Directory of Open Access Journals (Sweden)

Ie. P. Prekrasna

2015-10-01

Full Text Available The focus of the study was interaction of Candida tropicalis RomCu5 isolated from highland Ecuador ecosystem with soluble and insoluble copper compounds. Strain C. tropicalis RomCu5 was cultured in a liquid medium of Hiss in the presence of soluble (copper citrate and CuCl2 and insoluble (CuO and CuCO3 copper compounds. The biomass growth was determined by change in optical density of culture liquid, composition of the gas phase was measured on gas chromatograph, redox potential and pH of the culture fluid was defined potentiometrically. The concentration of soluble copper compounds was determined colorimetrically. Maximal permissible concentration of Cu2+ for C. tropicalis RomCu5 was 30 000 ppm of Cu2+ in form of copper citrate and 500 ppm of Cu2+ in form of CuCl2. C. tropicalis was metabolically active at super high concentrations of Cu2+, despite the inhibitory effect of Cu2+. C. tropicalis immobilized Cu2+ in the form of copper citrate and CuCl2 by it accumulation in the biomass. Due to medium acidification C. tropicalis dissolved CuO and CuCO3. High resistance of C. tropicalis to Cu2+ and ability to interact with soluble and insoluble copper compounds makes it biotechnologically perspective.

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.

Dislocation density and mechanical threshold stress in OFHC copper subjected to SHPB loading and plate impact

Energy Technology Data Exchange (ETDEWEB)

Hu, Qiushi [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Zhao, Feng, E-mail: ifpzfeng@163.com [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Fu, Hua; Li, Kewu [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Liu, Fusheng [Key Laboratory of Advanced Technologies of Materials, Southwest Jiaotong University, Chengdu, Sichuan, 610031 (China)

2017-05-17

The dislocation density and mechanical threshold stress (MTS) of oxygen-free high-thermal-conductivity (OFHC) copper loaded at strain rates in the range of 10{sup 2} to 10{sup 6} s{sup −1} were measured. Moderate-strain-rate (10{sup 2} to 10{sup 4} s{sup −1}) experiments were performed using a Split Hopkinson Pressure Bar (SHPB). A steel collar was placed around each specimen to control the maximum loading strain. High-strain-rate (10{sup 5} to 10{sup 6} s{sup −1}) experiments were carried out using a 57-mm-bore single-stage gas gun. The radial release effect was eliminated using the momentum trapping technique. The loaded samples were recovered, and the dislocation characteristics and dislocation density were determined by X-ray diffraction profile analysis. The fraction of the screw dislocation was found to decrease with increasing loading strain and strain rate. The dislocation density was found to lie between 1.8×10{sup 14} and 2.2×10{sup 15} m{sup −2}. Quasi-static reload compression tests were performed on the recovered samples at room temperature. The mechanical threshold stress (or the flow stress at 0 K) was obtained by fitting the reload stress–strain data to the MTS model. The results of analysis of the equivalent strain, mechanical threshold stress, and dislocation density measurements suggest that the relation between the mechanical threshold stress and the dislocation density can be described well by the Taylor relationship.

Corrections to the density-functional theory electronic spectrum: Copper phthalocyanine

DEFF Research Database (Denmark)

Vazquez, Hector; Jelinek, P.; Brandbyge, Mads

2009-01-01

A method for improving the electronic spectrum of standard Density-Functional Theory (DFT) calculations (i.e., LDA or GGA approximations) is presented, and its application is discussed for the case of the copper phthalocyanine (CuPc) molecule. The method is based on a treatment of exchange...... and correlation in a many-body Hamiltonian, and it leads to easy-to-evaluate corrections to the DFT eigenvalues. Self-interaction is largely corrected, so that the modified energy levels do not suffer from spurious crossings, as often encountered for CuPc in DFT, and they remedy the standard underestimation...... or semiempirical functionals for molecular levels, it can be easily applied to any local-orbital DFT approach, improving on several important limitations of standard DFT methods....

Copper wire theft and high voltage electrical burns.

Science.gov (United States)

Francis, Eamon C; Shelley, Odhran P

2014-01-01

High voltage electrical burns are uncommon. However in the midst of our economic recession we are noticing an increasing number of these injuries. Copper wire is a valuable commodity with physical properties as an excellent conductor of electricity making it both ubiquitous in society and prized on the black market. We present two consecutive cases referred to the National Burns Unit who sustained life threatening injuries from the alleged theft of high voltage copper wire and its omnipresence on an international scale.

The Copper concentration variation to physical properties of high copper amalgam alloy

Directory of Open Access Journals (Sweden)

Aminatun Aminatun

2006-09-01

Full Text Available The function of copper (Cu inside amalgam is to increase hardness and impact force and to decrease thermal expansion coefficient. In general, amalgam which is used in dentistry and available in the market is contain Cu 22%, while the maximum Cu concentration is 30%. It is necessary to determine the concentration Cu does generate the best physical properties to be used as dental restorative agent. Amalgam is made by mixing blended-metal Ag-Sn-Cu (with Cu concentration of 13%, 21%, 22%, and 29% and Hg, stirred manually in a bowl for 15 minutes,leave it in temperature 27°C for 24 hours to become hardened. The result of X-Ray Diffractometer (XRD, analyzed by Rietveld method and Rietica program, shows amalgam with Cu 29% concentration for Cu3Sn compound density is 31.790 sma/Å3, for Ag2Hg3 compound is 41.733 sma/ Å3, a Cu3Sn relative weight percentage of 43.23%, Ag2Hg3 of 54.54%, Cu 7Hg6 of 2.23% and hardness of Cu 29% is 90.700 ± 0.005 kgf/mm2. These numbers are the highest values on Cu 29% concentrations compared to other copper concentration variants. Whereas amalgam thermal expansion coefficient on Cu 29% is (2.17 ± 0.9110-3 mm/°C is the lowest value compared to other Cu concentration. The conclution is that adding Cu concentration into amalgam will increase density value, Cu3Sn relative weight percentage, hardness level and will decrease amalgam thermal expansion coefficient. Amalgam 29% Cu concentration has better physical properties compared to amalgam Cu 22% concentration.

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)

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...

Switching operation and degradation of resistive random access memory composed of tungsten oxide and copper investigated using in-situ TEM.

Science.gov (United States)

Arita, Masashi; Takahashi, Akihito; Ohno, Yuuki; Nakane, Akitoshi; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

2015-11-27

In-situ transmission electron microscopy (in-situ TEM) was performed to investigate the switching operation of a resistive random access memory (ReRAM) made of copper, tungsten oxide and titanium nitride (Cu/WOx/TiN). In the first Set (Forming) operation to initialize the device, precipitation appeared inside the WOx layer. It was presumed that a Cu conducting filament was formed, lowering the resistance (on-state). The Reset operation induced a higher resistance (the off-state). No change in the microstructure was identified in the TEM images. Only when an additional Reset current was applied after switching to the off-state could erasure of the filament be seen (over-Reset). Therefore, it was concluded that structural change relating to the resistance switch was localized in a very small area around the filament. With repeated switching operations and increasing operational current, the WOx/electrode interfaces became indistinct. At the same time, the resistance of the off-state gradually decreased. This is thought to be caused by Cu condensation at the interfaces because of leakage current through the area other than through the filament. This will lead to device degradation through mechanisms such as endurance failure. This is the first accelerated aging test of ReRAM achieved using in-situ TEM.

A brief review of cavity swelling and hardening in irradiated copper and copper alloys

International Nuclear Information System (INIS)

Zinkle, S.J.

1990-01-01

The literature on radiation-induced swelling and hardening in copper and its alloy is reviewed. Void formation does not occur during irradiation of copper unless suitable impurity atoms such as oxygen or helium are present. Void formation occurs for neutron irradiation temperatures of 180 to 550 degree C, with peak swelling occurring at ∼320 degree C for irradiation at a damage rate of 2 x 10 -7 dpa/s. The post-transient swelling rate has been measured to be ∼0.5%/dpa at temperatures near 400 degree C. Dispersion-strengthened copper has been found to be very resistant to void swelling due to the high sink density associated with the dispersion-stabilized dislocation structure. Irradiation of copper at temperatures below 400 degree C generally causes an increase in strength due to the formation of defect clusters which inhibit dislocation motion. The radiation hardening can be adequately described by Seeger's dispersed barrier model, with a barrier strength for small defect clusters of α ∼ 0.2. The radiation hardening apparently saturates for fluences greater than ∼10 24 n/m 2 during irradiation at room temperature due to a saturation of the defect cluster density. Grain boundaries can modify the hardening behavior by blocking the transmission of dislocation slip bands, leading to a radiation- modified Hall-Petch relation between yield strength and grain size. Radiation-enhanced recrystallization can lead to softening of cold-worked copper alloys at temperatures above 300 degree C

Effects of Si3+ and H+ Irradiation on Tungsten Evaluated by Internal Friction Method

International Nuclear Information System (INIS)

Hu Jing; Wang Xianping; Fang Qianfeng; Liu Changsong; Zhang Yanwen; Zhao Ziqiang

2013-01-01

Effects of Si 3+ and H + irradiation on tungsten were investigated by internal friction (IF) technique. Scanning electron microscope (SEM) analysis revealed that sequential dual Si+H irradiation resulted in more serious damage than single Si irradiation. After irradiation, the IF background was significantly enhanced. Besides, two obvious IF peaks were initially found in temperature range of 70∼330 K in the sequential Si+H irradiated tungsten sample. The mechanism of increased IF background for the irradiated samples was suggested to originate from the high density dislocations induced by ion irradiation. On the other hand, the relaxation peak P L and non-relaxation peak P H in the Si+H irradiated sample were ascribed to the interaction process of hydrogen atoms with mobile dislocations and transient processes of hydrogen redistribution, respectively. The obtained experimental results verified the high sensitivity of IF method on the irradiation damage behaviors in nuclear materials

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

Determination of the temperature dependence of tungsten erosion

International Nuclear Information System (INIS)

Maier, H.; Greuner, H.; Toussaint, U. von; Balden, M.; Böswirth, B.; Elgeti, S.

2015-01-01

We present the results of erosion measurements on actively cooled tungsten samples at quasi-constant surface temperature conditions performed in the high heat flux facility GLADIS. The samples were exposed to a H beam at a central power density of 10 MW/m 2 up to a fluence of 10 26 m −2 . We observe a weak temperature dependence of the erosion yield. The data are compared with similar data obtained from loading with a H beam with He admixture. Both datasets are analysed in a probabilistic approach. We obtain activation energies of 0.04 eV and 0.06 eV for the cases with and without He, respectively

Implantation driven permeation behavior of deuterium through pure tungsten

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Hirofumi E-mail: nakamura@tpl.tokai.jaeri.go.jp; Hayashi, Takumi; Nishi, Masataka; Arita, Makoto; Okuno, Kenji

2001-09-01

Implantation driven permeation behavior of deuterium through pure tungsten has been investigated to estimate the amount of tritium permeation through its barrier in a thermo-nuclear fusion device. The permeation experiments were performed on pure tungsten foil of 25 {mu}m thickness under conditions of incident flux of 1.9x10{sup 18}-1.1x10{sup 19} D{sup +}/m{sup 2}s, incident ion energy of 200-2000 eV, and specimen temperature of 512-660 K. As a result of this steady-state permeation experiment, the rate-determining process of deuterium permeation was found to be controlled by diffusion at both implanted and permeated sides. On the other hand, transient permeation was strongly affected by trap effect in the specimen. Simulation analysis using TMAP code on transient permeation behavior indicates the existence of a trap site with a trap energy of nearly 1eV and with a trap density of over several ten's ppm in tungsten.

Implantation driven permeation behavior of deuterium through pure tungsten

International Nuclear Information System (INIS)

Nakamura, Hirofumi; Hayashi, Takumi; Nishi, Masataka; Arita, Makoto; Okuno, Kenji

2001-01-01

Implantation driven permeation behavior of deuterium through pure tungsten has been investigated to estimate the amount of tritium permeation through its barrier in a thermo-nuclear fusion device. The permeation experiments were performed on pure tungsten foil of 25 μm thickness under conditions of incident flux of 1.9x10 18 -1.1x10 19 D + /m 2 s, incident ion energy of 200-2000 eV, and specimen temperature of 512-660 K. As a result of this steady-state permeation experiment, the rate-determining process of deuterium permeation was found to be controlled by diffusion at both implanted and permeated sides. On the other hand, transient permeation was strongly affected by trap effect in the specimen. Simulation analysis using TMAP code on transient permeation behavior indicates the existence of a trap site with a trap energy of nearly 1eV and with a trap density of over several ten's ppm in tungsten

Copper wire theft and high voltage electrical burns

Science.gov (United States)

Francis, Eamon C; Shelley, Odhran P

2014-01-01

High voltage electrical burns are uncommon. However in the midst of our economic recession we are noticing an increasing number of these injuries. Copper wire is a valuable commodity with physical properties as an excellent conductor of electricity making it both ubiquitous in society and prized on the black market. We present two consecutive cases referred to the National Burns Unit who sustained life threatening injuries from the alleged theft of high voltage copper wire and its omnipresence on an international scale. PMID:25356371

Characterization of ASTM round-robin tungsten-powder samples

International Nuclear Information System (INIS)

Slettevold, C.A.; Biermann, A.H.

1975-01-01

The Lawrence Livermore Laboratory Particle Characterization Laboratory Group has participated in an industry-wide round-robin investigation on characterization of tungsten powder. sponsored by the ASTM Subcommittee on Refractory-Metal Powders (B-09.3). The analyses performed at the suggestion of the ASTM subcommittee included measurements of tap density, apparent density, true density, average particle size, and surface area. Determinations of particle-weight and size distributions were also performed and particle inspection conducted by microscopy. This report describes the equipment and procedures used and summarizes the results of these analyses. (9 tables, 17 fig) (U.S.)

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.

An indirect sequential determination of phosphorus and arsenic in high-purity tungsten and its compounds by atomic-absorption spectrophotometry

International Nuclear Information System (INIS)

Tekula-Buxbaum, P.

1981-01-01

An indirect atomic-absorption spectrophotometric method based on selective extraction of heteropolymolybdic acids has been developed for determination of small quantities of P and As in high-purity tungsten metal and tungsten compounds. The method is suitable for determination of 5-100 ppm of phosphorus and arsenic. The relative standard deviation is 38-5% for P and 31-3% for As, depending on the concentrations. (auth.)

High-density metals and metallic composites for improved fragmentation submunitions

International Nuclear Information System (INIS)

Craig, B.G.; Honnell, R.E.; Lederman, G.F. Jr.; Sandstrom, D.J.

1975-08-01

The fragmentation of cases (50.8-mm-id) made of tungsten, a tungsten alloy, and depleted uranium (D-38) can be controlled, and velocities greater than 1 mm/μs can be achieved for lethal size fragment weights. Fragmentation was controlled by internal grooves, by internal screens, and by a spheroid-in-weak-matrix scheme. A thin polymer liner was used inside of a grooved tungsten case in one experiment; this system performed exceptionally well. The ease of fabricating cases with D-38 or with the tungsten-alloy spheroid-in-matrix scheme offers an attractive advantage over tungsten and tungsten alloy

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

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

Study of the picture change error at the 2nd order Douglas Kroll Hess level of theory. Electron and spin density and structure factors of the Bis[bis(methoxycarbimido) aminato] copper (II) complex

International Nuclear Information System (INIS)

Bučinský, Lukáš; Biskupič, Stanislav; Jayatilaka, Dylan

2012-01-01

Graphical abstract: The dependence of the radial distribution of the spin density in the vicinity of the nucleus on the formal oxidation state of the copper atom is shown on the top three figures. Note also the large impact of PCE as well as relativistic effects. The bottom three figures present the relativistic effects and PCE in the electron density of the [CuL 2 ] model compound (of the size 1 bohr 2 ). PCE is very little affecting the relativistic effects in the electron density close to the nucleus of copper atom, i.e. the PCE in the relativistic effects of the electron density are hardly discernable in the case of compounds containing copper. Highlights: ► The extent of PCE in a model compound containing copper atom is presented. ► The spin/electron density along bond the Cu–N is the most affected by PCE only at the nucleus of the copper atom. ► The 2D inspection of relativistic effects in electron/spin densities is not sensitive to PCE. ► Structure factors are an order of magnitude less affected by PCE than by relativistic effects. ► PCE in the Mulliken populations and spin contamination is considered. - Abstract: The analytic correction and the extent of the picture change error (PCE) at the scalar 2nd order Douglas–Kroll–Hess level of theory is considered. The one-dimensional (1D), two-dimensional (2D) spin/electron densities and/or difference densities, structure factors and Mulliken populations of the Bis [bis-(methoxycarbimido) aminato] copper (II) model compound are presented. For further comparison the radial distributions of the electron and spin density of the copper atom (as well as of the copper di-cation) are presented. In addition, the infinite order two component (IOTC) radial distributions of electron and spin density of the copper atom and copper dication are presented as well. The PCE is almost hidden in the 2D densities of the studied model compound. The 1D electron/spin difference densities along the Cu–N bond show the

Experimental Studies of the Effects of Anode Composition and Process Parameters on Anode Slime Adhesion and Cathode Copper Purity by Performing Copper Electrorefining in a Pilot-Scale Cell

Science.gov (United States)

Zeng, Weizhi; Wang, Shijie; Free, Michael L.

2016-10-01

Copper electrorefining tests were conducted in a pilot-scale cell under commercial tankhouse environment to study the effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity. Three different types of anodes (high, mid, and low impurity levels) were used in the tests and were analyzed under SEM/EDS. The harvested copper cathodes were weighed and analyzed for impurities concentrations using DC Arc. The adhered slimes and released slimes were collected, weighed, and analyzed for compositions using ICP. It was shown that the lead-to-arsenic ratio in the anodes affects the sintering and coalescence of slime particles. High current density condition can improve anode slime adhesion and cathode purity by intensifying slime particles' coalescence and dissolving part of the particles. Wide cathode blanks can raise the anodic current densities significantly and result in massive release of large slime particle aggregates, which are not likely to contaminate the cathode copper. Low flow rate can cause anode passivation and increase local temperatures in front of the anode, which leads to very intense sintering and coalescence of slime particles. The results and analyses of the tests present potential solutions for industrial copper electrorefining process.

Measurement and Analysis of Density of Molten Ni-W Alloys

Institute of Scientific and Technical Information of China (English)

FANG Liang; XIAO Feng; TAO Zainan; MuKai Kusuhiro

2005-01-01

The density of molten Ni-W alloys was measured with a modified pycnometric method. It is found that the density of the molten Ni- W alloys decreases with temperature rising, but increases with the increase of tungsten concentration in the alloys. The molar volume of molten Ni- W binary alloys increases with the increase of temperature and tungsten concentration. The partial molar volume of tungsten in liquid Ni- W binary alloy has been calculated approximately as ( - 1.59+ 5.64 × 10-3 T) × 10-6m3 ·mol-1.

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.

Native copper in Permian Mudstones from South Devon: A natural analogue of copper canisters for high-level radioactive waste

International Nuclear Information System (INIS)

Milodowski, A.E.; Styles, M.T.; Werme, L.; Oversby, V.M.

2001-01-01

Native copper (>99.9% Cu) sheets associated with complex uraniferous and vanadiferous concretions in Upper Permian Mudstones from south Devon (United Kingdom) have been studied as a 'natural analogue' for copper canisters designed to be used in the isolation of spent fuel and high-level radioactive wastes (HLW) for deep geological disposal. Detailed analysis demonstrates that the copper formed before the mudstones were compacted. The copper displays complex corrosion and alteration. The earliest alteration was to copper oxides, followed sequentially by the formation of copper arsenides, nickel arsenide and copper sulphide, and finally nickel arsenide accompanied by nickel-copper arsenide, copper arsenide and uranium silicates. Petrographic observations demonstrate that these alteration products also formed prior to compaction. Consideration of the published history for the region indicates that maximum compaction of the rocks will have occurred by at least the Lower Jurassic (i.e. over 176 Ma ago). Since that time the copper sheets have remained isolated by the compacted mudstones and were unaffected by further corrosion until uplift and exposure to present-day surface weathering

The use of tungsten as a chronically implanted material

Science.gov (United States)

Shah Idil, A.; Donaldson, N.

2018-04-01

This review paper shows that tungsten should not generally be used as a chronically implanted material. The metal has a long implant history, from neuroscience, vascular medicine, radiography, orthopaedics, prosthodontics, and various other fields, primarily as a result of its high density, radiopacity, tensile strength, and yield point. However, a crucial material criterion for chronically implanted metals is their long-term resistance to corrosion in body fluids, either by inherently noble metallic surfaces, or by protective passivation layers of metal oxide. The latter is often assumed for elemental tungsten, with references to its ‘inertness’ and ‘stability’ common in the literature. This review argues that in the body, metallic tungsten fails this criterion, and will eventually dissolve into the soluble hexavalent form W6+, typically represented by the orthotungstate WO42- (monomeric tungstate) anion. This paper outlines the metal’s unfavourable corrosion thermodynamics in the human physiological environment, the chemical pathways to either metallic or metal oxide dissolution, the rate-limiting steps, and the corrosion-accelerating effects of reactive oxidising species that the immune system produces post-implantation. Multiple examples of implant corrosion have been reported, with failure by dissolution to varying extents up to total loss, with associated emission of tungstate ions and elevated blood serum levels measured. The possible toxicity of these corrosion products has also been explored. As the field of medical implants grows and designers explore novel solutions to medical implant problems, the authors recommend the use of alternative materials.

Investigation of field emission properties of laser irradiated tungsten

International Nuclear Information System (INIS)

Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Jalil, Sohail Abdul; Rafique, Muhammad Shahid

2018-01-01

Nd:YAG laser irradiation of Tungsten (W) has been performed in air at atmospheric pressure for four laser fluences ranging from 130 to 500 J/cm 2 . Scanning electron microscope analysis revealed the formation of micro and nanoscale surface features including cones, grains, mounds and pores. Field emission (FE) studies have been performed in a planar diode configuration under ultra-high vacuum conditions by recording I-V characteristics and plotting corresponding electric field (E) versus emission current density (J). The Fowler-Nordheim (FN) plots are found to be linear confirming the quantum mechanical tunneling phenomena for the structured targets. The irradiated samples at different fluences exhibit a turn-on field, field enhancement factor β and a maximum current density ranging from 5 to 8.5 V/μm, 1300 to 3490 and 107 to 350 μA/cm 2 , respectively. The difference in the FE properties is attributed to the variation in the nature and density of the grown structures at different fluences. (orig.)

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

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.

Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

Science.gov (United States)

Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

2012-07-01

The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm2) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

International Nuclear Information System (INIS)

Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

2012-01-01

The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm 2 ) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

Testing Hadronic Interaction Models using a Highly Granular Silicon-Tungsten Calorimeter

CERN Document Server

Bilki, B.; Schlereth, J.; Xia, L.; Deng, Z.; Li, Y.; Wang, Y.; Yue, Q.; Yang, Z.; Eigen, G.; Mikami, Y.; Price, T.; Watson, N.K.; Thomson, M.A.; Ward, D.R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Carloganu, C.; Chang, S.; Khan, A.; Kim, D.H.; Kong, D.J.; Oh, Y.D.; Blazey, G.C.; Dyshkant, A.; Francis, K.; Lima, J.G.R.; Salcido, P.; Zutshi, V.; Boisvert, V.; Green, B.; Misiejuk, A.; Salvatore, F.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Suehara, T.; Tomita, T.; Ueno, H.; Yoshioka, T.; Apostolakis, J.; Folger, G.; Ivantchenko, V.; Ribon, A.; Uzhinskiy, V.; Cauwenbergh, S.; Tytgat, M.; Zaganidis, N.; Hostachy, J.Y.; Morin, L.; Gadow, K.; Göttlicher, P.; Günter, C.; Krüger, K.; Lutz, B.; Reinecke, M.; Sefkow, F.; Feege, N.; Garutti, E.; Laurien, S.; Lu, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Kaplan, A.; Norbeck, E.; Northacker, D.; Onel, Y.; Kim, E.J.; van Doren, B.; Wilson, G.W.; Wing, M.; Bobchenko, B.; Chadeeva, M.; Chistov, R.; Danilov, M.; Drutskoy, A.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Popov, V.; Rusinov, V.; Tarkovsky, E.; Besson, D.; Popova, E.; Gabriel, M.; Kiesling, C.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Callier, S.; Conforti di Lorenzo, S.; Cornebise, P.; Doublet, Ph.; Dulucq, F.; Faucci-Giannelli, M.; Fleury, J.; Frisson, T.; Kégl, B.; van der Kolk, N.; Li, H.; Martin-Chassard, G.; Richard, F.; de la Taille, Ch.; Pöschl, R.; Raux, L.; Rouëne, J.; Seguin-Moreau, N.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J.-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Magniette, F.; Matthieu, A.; Mora de Freitas, P.; Videau, H.; Augustin, J.-E.; David, J.; Ghislain, P.; Lacour, D.; Lavergne, L.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Jeans, D.; Götze, M.

2015-09-11

A detailed study of hadronic interactions is presented using data recorded with the highly granular CALICE silicon-tungsten electromagnetic calorimeter. Approximately 600,000 selected negatively changed pion events at energies between 2 and 10 GeV have been studied. The predictions of several physics models available within the GEANT4 simulation tool kit are compared to this data. Although a reasonable overall description of the data is observed, there are significant quantitative discrepancies in the longitudinal and transverse distributions of reconstructed energy.

Insensitive high-energy energetic structural material of tungsten-polytetrafluoroethylene-aluminum composites

Directory of Open Access Journals (Sweden)

Liu Wang

2015-11-01

Full Text Available Energetic structural material is a kind of materials that are inert under normal conditions but could produce exothermic chemical reaction when subjected to impact. This report shows a kind of energetic structural material of tungsten (W-polytetrafluoroethylene (PTFE-aluminum (Al with density of 4.12 g/cm3, excellent ductility and dynamic compressive strength of 96 MPa. Moreover, 50W-35PTFE-15Al (wt% can exhibit a high reaction energy value of more than 2 times of TNT per unit mass and 5 times of TNT per unit volume, respectively, but with excellent insensitivity compared with traditional explosives. Under thermal conditions, the W-PTFE-Al composite can keep stable at 773 K. Under impact loading, when the strain rate up to ∼4820 s−1 coupled with the absorbed energy per unit volume of 120 J/cm3, deflagration occurs and combustion lasts for 500 μs. During impact compressive deformation, the PTFE matrix is elongated into nano-fibers, thus significantly increases the reaction activity of W-PTFE-Al composites. The nano-fiber structure is necessary for the reaction of W-PTFE-Al composites. The formation of PTFE nano-fibers must undergo severe plastic deformation, and therefore the W-PTFE-Al composites exhibit excellent insensitivity and safety. Furthermore, the reaction mechanisms of W-PTFE-Al composites in argon and in air are revealed.

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.

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.

XES studies of density of states of high temperature superconductors

Science.gov (United States)

Jasiolek, Gabriel

1991-01-01

X-ray emission spectroscopic studies concerning the superconducting crystals, thin films, and ceramics of the Y-Ba-Cu-O, Tm-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Bi-Pb-Sr-Ca-Cu-O, and Tl-Ba-Ca-Cu-O types are presented. The contributions of the 13d(9)L, 13d(10)L, 13d(10)LL, and 13d(10)L(2) configurations, where L denotes a ligand hole at the oxygen orbitals in the spectroscopic pattern of these superconductors are discussed. An attempt to connect the x-ray 'as registered' Cu L(alpha) emission spectra with the density of states close to the Fermi level, considering an influence of the CuL3 absorption edge, is presented. The corrected intensity distributions below the Fermi level are found to correspond to the theoretical density of states. Furthermore, an approach to the average valence of copper basing on the account of the self-absorption and fluorescence effects and on the configurations listed above is shown. The average valence of copper in the materials investigated is estimated to lie in the range of +2.10 to 2.32 when the formal trivalent copper is considered as that characterized by the 13d(9)L configuration. The density of states at the Fermi level was estimated to be 2.4 states/eV-cell for a Bi-Sr-Ca-Cu-O crystal and 3.6 states/eV-cell for a Tl-Ba-Ca-CU-O ceramic.

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)

EUV spectroscopy of highly charged tungsten ions relevant to hot plasmas

International Nuclear Information System (INIS)

Biedermann, C.; Radtke, R.; Fuchs, T.; Fussmann, G.; Schwob, J.L.; Mandelbaum, P.; Doron, R.

2001-01-01

The radiation from tungsten ions in the extreme ultraviolet spectral region was investigated using a 2-m grazing-incidence spectrometer in conjunction with the Berlin electron beam ion trap. Operating EBIT at beam energies between 900 eV and 1.7 keV In-like W 25+ to Sr-like W 36+ ions could selectively be excited, and a bright emission band of about 2 A width was measured which shifts from 50 to 54 A when raising the charge state. The band of partially unresolved lines originates from 4l-4l' transitions of ions having an open 4d subshell. Atomic structure calculations with the HULLAC code package show that the narrowing and shift of the line band emission can be interpreted in the framework of the unresolved transition array using mixed configurations. The theoretical spectrum analysis applies a collisional-radiative model to account for the low electron density of EBIT and reproduces the variations of the observed emission pattern. (orig.)

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

Chemistry of the copper silicon interface

International Nuclear Information System (INIS)

Ford, M.J.; Sashin, V.A.; Nixon, K.

2002-01-01

Full text: Copper and silicon readily interdiffuse, even at room temperature, to form an interface which can be several nanometers thick. Over the years considerable effort has gone into investigating the diffusion process and chemical nature of the interface formed. Photoemission measurements give evidence for the formation of a stable suicide with a definite stoichiometry, Cu 3 Si. This is evidenced by splitting of the Si LVV Auger line and slight shifts and change in shape of the copper valence band density of states as measured by ultra-violet photoemission. In this paper we present calculations of the electronic structure of copper suicide, bulk copper and silicon, and preliminary measurements of the interface by electron momentum spectroscopy. Densities of states for copper and copper suicide are dominated by the copper 3d bands, and difference between the two compounds are relatively small. By contrast, the full band structures are quite distinct. Hence, experimental measurements of the full band structure of the copper on silicon interface, for example by EMS, have the potential to reveal the chemistry of the interface in a detailed way