Showing papers on "Tungsten published in 1969"
01 Jan 1969
267 citations
225 citations
TL;DR: In this paper, a study was made of the mechanical properties of vacuum arc-melted tungsten and rhenium-rhenium alloys in the temperature range 77 °-810 °K in order to elucidate the mechanism by which the addition of Rhenium adds lower the ductile-brittle transition temperature of Tungsten.
Abstract: A study was made of the mechanical properties of vacuum arc-melted tungsten and tungsten-rhenium alloys in the temperature range 77 °–810 °K in order to elucidate the mechanism by which rhenium additions lower the ductile-brittle transition temperature of tungsten. The temperature and strain rate dependency of the yield stress of tungsten are reduced by alloying with rhenium, inferring a reduction in the Peierls stress. The reduction in the transition temperature is attributed to the reduced Peierls stress through its effect on the mobility and rate of multiplication of dislocations.
182 citations
TL;DR: Low energy electron diffraction oxygen adsorption kinetics on planes of tungsten at coverages below monolayer and work function measurements were studied in this paper, where the work function was defined as
115 citations
TL;DR: In this paper, a thermal faceting of tungsten single crystal surfaces in oxygen was performed using vibrating-capacitor work function probe with low energy electron diffraction.
111 citations
Patent•
23 Jun 1969TL;DR: In this paper, strong, hard, impact-resistant bodies comprising tungsten carbide bonded with from 3 to 25% by weight of heterogeneous cobalt-tungsten solid-solution alloy, useful as cutting tools, are prepared by heating an intimately mixed cobalt/tungsten carbide powder to a temperature above 1000* C and consolidating the powder to density of at least 98% of its theoretical density.
Abstract: Strong, hard, impact-resistant bodies comprising tungsten carbide bonded with from 3 to 25% by weight of heterogeneous cobalt-tungsten solid-solution alloy, useful as cutting tools, are prepared by heating an intimately mixed cobalt/tungsten carbide powder to a temperature above 1000* C and consolidating the powder to a density of at least 98% of its theoretical density, having either. 1. MIXED A CARBON-RICH AND A CARBON-DEFICIENT POWDER TOGETHER PRIOR TO CONSOLIDATION TO PRODUCE A NON-HOMOGENEOUS BINDER; 2. ADDED FREE CARBON TO A CARBON-DEFICIENT POWDER TO PRODUCE LOCAL AREAS WHERE TUNGSTEN IS REMOVED FROM THE BINDER ALLOY AS TUNGSTEN CARBIDE; OR 3. ALLOWED A PORTION OF THE CARBON IN THE TUNGSTEN CARBIDE TO OXIDIZE DURING CONSOLIDATION TO PRODUCE AREAS IN THE BINDER PHASE WHICH ARE THEN CARBON DEFICIENT AND HIGH IN TUNGSTEN.
105 citations
Patent•
03 Oct 1969TL;DR: In this article, a method for the manufacture of an electrode for use in electrochemical processes, which comprises forming on the surface of a support of a film-forming metal of the group of titanium, zirconium, niobium, tantalum and tungsten or an alloy principally of one of these metals, is described.
Abstract: A method for the manufacture of an electrode for use in electrochemical processes, which comprises forming on the surface of a support of film-forming metal of the group of titanium, zirconium, niobium, tantalum and tungsten or an alloy principally of one of these metals, a layer of an operative electrode material, applying over the said layer a coating comprising a thermally decomposable organo-compound of a film-forming metal of the group of alkoxides and alkoxy-halides of titanium, zirconium, niobium, tantalum and tungsten wherein the halogen is chlorine, bromine or fluorine in a liquid vehicle and heating the coating to convert the organo-compound of the film-forming metal to an oxide.
84 citations
TL;DR: Work-function and Fowler-Nordheim preexponential changes for incremental oxygen adsorption at 20 and 100°K have been measured on the (120, (111), (100, (100), (211), and (110) planes of a tungsten field emitter.
Abstract: Work‐function and Fowler–Nordheim pre‐exponential changes for incremental oxygen adsorption at 20 and 100°K have been measured on the (120), (111), (100), (211), and (110) planes of a tungsten field emitter. On the (110) plane Δφ = 0.6 eV at full coverage, while Δφ = 1.2–1.4 eV on most other planes. A model of O adsorption based on the partial filling of an affinity band is presented to account for this and other features of the results. Diffusion into various planes was also investigated. It was found that low‐temperature boundary diffusion at 25°K leaves the (110) plane bare. Diffusion in the chemisorbed layer starts at 400°K on (110) with an activation energy of 15 kcal, and on other planes at temperatures of ∼ 500°K.
79 citations
TL;DR: In this article, the epitaxial growth of copper vapour deposited onto the surface of a tungsten single crystal has been studied using low energy diffraction, Auger electron emission and electron energy loss spectra, while in a separate apparatus, work function changes have been measured.
72 citations
70 citations
TL;DR: Field Ion Microscope Observations of Cluster Formation in Metal Deposits on Tungsten Surfaces (FIMMS) as mentioned in this paper...,.. ]..
Abstract: Field Ion Microscope Observations of Cluster Formation in Metal Deposits on Tungsten Surfaces
TL;DR: The first structures observed to form on both the (100) and (110) surfaces were due to the adsorption of cesium in an ionic form, while the last structures are due to a second layer of metallic Cesium.
TL;DR: In this article, the parent hexacarbonyls of molybdenum and tungsten have been prepared for the first time by the direct interaction of the parenthexacarbonyls with iodine at room temperature under the influence of ultraviolet radiation.
Abstract: Diiodotetracarbonyls of molybdenum and tungsten(II) have been prepared for the first time by the direct interaction of the parent hexacarbonyls with iodine at room temperature under the influence of ultraviolet radiation. Reaction of the iodocarbonyls with donor ligands such as triphenylphosphine, triphenylarsine, and triphenylstibine generally gives neutral substitution products, but the reaction between the molybdenum compound and triphenylphosphine yielded the previously reported triphenylphosphonium salt of the triiodotricarbonyl(triphenylphosphine)-molybdate(II) ion. Diiodotricarbonylbis(triphenylphosphine)tungsten(II) loses carbon monoxide on heating under vacuum to give the corresponding blue dicarbonyl compound. The dicarbonyl dissolved in dichloromethane readily absorbs carbon monoxide to reform the tricarbonyl and the compounds therefore represent a further carbon monoxide carrying system.
TL;DR: In this article, a simple model is proposed which predicts the composition of sputtered multicomponent thin films, applied to such problems as alloy sputtering, gas incorporation into thin films and compound formation.
Abstract: A simple model is proposed which predicts the composition of sputtered multicomponent thin films. The model is applied to such problems as alloy sputtering, gas incorporation into thin films, and compound formation. Several practical systems are considered such as the sputtering of Gd3Fe5 and Ni4Fe alloys and the incorporation of argon, oxygen, and nitrogen into tungsten films. The results of these studies suggest that the film composition is a strong function of vapor pressure, sputtering rate, atomic size, system geometry, sticking probabilities, and sputtering coefficients.
TL;DR: In this article, the authors examined the shockloading behavior of a sintered porous tungsten with a density of 12.64 g/cm3 (corresponding to 65.3% of the density of the solid tengsten).
Abstract: Data are presented from a study conducted to examine the shock‐loading behavior of a sintered porous tungsten with a density of 12.64 g/cm3 (corresponding to 65.3% of the density of solid tungsten). The experiments were performed by using a gas gun and high explosives. Hugoniot data obtained in the stress range between about 12 kbar and 1 Mbar indicate that compression of the porous material to a fully compacted state is essentially complete at 50 kbar. Above this level, a predicted Hugoniot, calculated from the Hugoniot of solid tungsten by using the Mie‐Gruneisen equation of state, agrees well with experimental data. Below 50 kbar the Hugoniot of the porous tungsten deviates from the predicted Hugoniot increasingly with decreasing stress. Propagated wave profiles at lower stresses are characterized by two precursor waves, the faster being a low‐level wave (∼0.2 kbar) traveling at about sonic velocity in the porous tungsten (∼3.04 mm/μsec). The slower precursor has an amplitude of 2.73 kbar and travels at 2.02 mm/μsec. The behavior of this porous tungsten is analogous to the behavior of sintered porous copper previously studied.
TL;DR: The absolute absorption coefficient of Ta, W, Re and Pt has been determined in the photon energy range 30-600eV by use of synchrotron radiation at the 7.5-GeV electron synchoretron DESY as discussed by the authors.
TL;DR: In this article, the field ion microscope was used for measuring the surface free energy anisotropy of tungsten, and a tip with a long shank and a small cone angle was used.
TL;DR: In this article, the adsorption of immobilely deposited and thermally equilibrated Cs layers has been studied on the (110), (211), (100), (111), (103), and (115) regions of a tungsten field emitter.
Abstract: The adsorption of immobilely deposited and thermally equilibrated Cs layers has been studied on the (110), (211), (100), (111), (103), and (115) regions of a tungsten field emitter. The work‐function‐vs‐coverage data permit resolution into adsorbate charge and effective dipole length, at least on the high work‐function planes. The results indicate ionic adsorption on (110) and probably (211) at low coverage, with charge diminishing on all planes as θ increases. Dipole lengths exceed the ionic radius of Cs by 1.4–2 A, indicating the effect of finite screening at the metal surface. The adsorption energies and their change with θ can be interpreted in terms of the “metallet” model.
TL;DR: In this article, the desorption kinetics of the atomic and oxide phases 1,2 ) have been studied to determine the composition of the surface film formed upon interaction of oxygen at low pressure with the surface of W and Mo single crystals.
TL;DR: A combined ion exchange spectrophotometric method was developed for the determination of molybdenum and tungsten in sea water as discussed by the authors, where the two elements were adsorbed quantitatively on Dowex 1-X8 (SCN-form) from sea water adjusted to 0.1 M in hydrochloric acid and ammonium thiocyanate.
TL;DR: In this article, internal friction, Young modulus and resistivity measurements for stage I interstitials in electron irradiated tungsten were performed for the first time in the lifetime of the electron.
Abstract: Internal friction, Young modulus and resistivity measurements for stage I interstitials in electron irradiated tungsten
TL;DR: In this article, a polycrystalline tungsten substrate was used to measure the mean adsorption lifetime and activation energy of atoms on a metal surface, where ν 0 is the vibrational frequency and E is the activation energy.
Abstract: Direct measurements of the mean adsorption lifetimes and the activation energies of silver and gold have been made on a polycrystalline tungsten substrate. The lifetime was determined by the time constant of the exponential increase of the surface concentration when an atomic beam impinged on the substrate. The activation energy was determined by the slope of the logarithm of the lifetime as a function of the inverse substrate temperature. The adsorption lifetime of atoms on a metal surface is τ=(1/ν0) exp (E/kT), where ν0 is the vibrational frequency and E is the activation energy. The experiments were conducted in an ultrahigh‐vacuum system free of hydrocarbon contamination. A clean substrate surface was obtained by heating in a partial pressure of oxygen for a long period of time and flashing to 2500°K before each data point was taken. The well‐defined surface condition and the precisely known temperature allow reliable interpretation of the experimental results. The experimental results for silver and...
TL;DR: In this paper, the authors show that the trapped gas atoms consist of substitutional gas atoms and associated point defects, and that all peaks below 1650°K are associated with desorption from sites within about 10 A of the crystal surfaces, while the single peak above 1700°K is the result of isotropic diffusion of ions which have penetrated more than 10 A.
Abstract: Clean (211) and (110) surfaces of tungsten have been bombarded with inert‐gas‐ion beams in the energy range 40 eV–5 keV. Thermal desorption spectra of the trapped gas show patterns of peaks characteristic of the ion and the face bombarded. The results are comparable to those obtained previously for a (100) tungsten surface. In particular, all peaks below 1650°K are associated with desorption from sites within about 10 A of the crystal surfaces, while the single peak above 1700°K is the result of isotropic diffusion of ions which have penetrated more than 10A. Evidence is presented to support the hypothesis that the trapping sites consist of substitutional gas atoms and associated point defects.
TL;DR: In this paper, the patterns of the 1H NMR spectra of phosphine carbonyl complexes of chromium, molybdenum, and tungsten synthesized up to the present time are explained.
TL;DR: In this paper, the effect of adsorbed gas layers on the ejection of electrons by rare-gas metastable atoms has been investigated for some tungsten surfaces, and the results showed that the ejected electron yield was sharply reduced following adsorption.
Abstract: The effect of adsorbed‐gas layers on the ejection of electrons by rare‐gas metastable atoms has been investigated for some tungsten surfaces. These surfaces were the (111) and (110) planes of a tungsten single crystal and an essentially (100) oriented polycrystalline tungsten ribbon. With nitrogen as the adsorbate the ejected‐electron yields were reduced by 42% on the polycrystalline ribbon and increased 1% on the (111) plane. The yield did not change for the (110) plane. With carbon monoxide as the adsorbate, the yield decreases were 63%, 51%, and 56% for the polycrystalline ribbon, the (100), and (111) planes, respectively. With hydrogen as the adsorbate the yield was decreased by 1% on the (110) plane and 4% on the (111) plane. In those cases where the ejected‐electron yield was sharply reduced following adsorption, the electron energy spectrum revealed a marked diminution of the number of high‐energy electrons and in the case of carbon monoxide on the (111) and (110) planes, essentially a “cutoff” in ...
01 Apr 1969
TL;DR: In ultrahigh vacuum, disulfides, diselenides, and ditellurides of molybdenum and tungsten in ultra-high vacuum were studied as discussed by the authors.
Abstract: Thermal stability and friction of disulfides, diselenides, and ditellurides of molybdenum and tungsten in ultrahigh vacuum
TL;DR: In this paper, a flash-filament spectroscopy was used to investigate the decomposition of acetylene, ethane, ethylene, and methane initially adsorbed on tungsten wires at 95°K.
Abstract: The decomposition of acetylene, ethylene, ethane, and methane initially adsorbed on tungsten wires at 95°K was investigated by flash-filament spectroscopy, with products identified by mass spectroscopy; the major gas-phase product was hydrogen in all four cases. The flash-filament spectrum of ethylene consists of two equal hydrogen peaks resulting from a two-step dehydrogenation of chemisorbed ethylene: *CH2–CH2*→ lim >200°K*CH=CH*+2H*, CH*=CH*→ lim >300°K(C2)+2H*, 2H*→ lim fastH2(g). Acetylene dehydrogenation follows Reactions (2) and (3). When compared to previous results obtained on iridium, ethylene is seen to be more unstable on tungsten than on iridium. [Reaction (1) proceeds at an appreciable rate above 200°K on tungsten but only above 400°K on iridium.] This difference in stability of surface ethylene is discussed in terms of the possible surface structures of ethylene imposed by the topography of the metal surface. Adsorption of ethane and methane at 95°K is interpreted in terms of the following...