Hydrogen solubilisation into and permeation through wall materials

Waelbroeck, F.; Ali-Khan, I.; Dietz, K.J.; Wienhold, P.

doi:10.1016/0022-3115(79)90514-2

Cited by 87 publications

(18 citation statements)

References 13 publications

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“…1͒ up to ϳ1770 K ͑at H 2 pressure 10 −6 -10 −4 Pa͒ results in the generation of atomic hydrogen and consequently in the radical increase in perme- ation flux. 1,21,22 One can evaluate the sticking coefficient for atoms, ␣ H , in the same way as ␣ H 2 ͓see Eq. ͑2͔͒,…”

Section: Permeation Methods To Study the Sticking Of H Atomsmentioning

confidence: 99%

Effects of bulk impurity concentration on the reactivity of metal surface: Sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen

Hatano

Watanabe

Livshits

et al. 2007

The Journal of Chemical Physics

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Nonmetallic impurities segregated onto metal surfaces are able to drastically decrease the chemical reactivity of metals. In the present paper, effects of bulk impurities on the reactivity of metallic surfaces were investigated in a wide temperature range on an example of the sticking of hydrogen molecules and atoms to Nb ͓polycrystalline, with mainly ͑100͔͒ containing solute oxygen. At all the investigated surface temperatures, T S ͑300-1400 K͒, we found the bulk oxygen concentration C O to have a strong effect on the integral probability, ␣ H 2 , of dissociative sticking of H 2 molecules followed by hydrogen solution in the metal lattice: ␣ H 2 monotonically decreased by orders of magnitude with increasing C O from 0.03 to 1.5 at. %. The sticking coefficient ␣ H 2 was found to depend on T S but not on the gas temperature. The effect of C O on ␣ H 2 is explained by the presence of oxygen-free sites ͑holes in coverage͒ serving as active centers of the surface reaction in the oxygen monolayer upon Nb. In contrast to H 2 molecules, H atoms were found to stick to, and be dissolved in, oxygen-covered Nb with a probability comparable to 1, depending neither on C O nor on T S . This proves that, unlike H 2 molecules, H atoms do stick to be dissolved mainly through regular surface sites covered by oxygen and not through the holes in coverage.

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Section: Permeation Methods To Study the Sticking Of H Atomsmentioning

confidence: 99%

Effects of bulk impurity concentration on the reactivity of metal surface: Sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen

Hatano

Watanabe

Livshits

et al. 2007

The Journal of Chemical Physics

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“…The model calculation of the permeation number W proposed by Waelbroeck et al 22) indicated that the permeation/dissolution through the Tienriched surface is controlled by the surface reactions, i.e. W ( 1, in the expected operation temperature range (603-883 K) if the wall thickness L is smaller than 100 mm.…”

Section: Change In the Surface State By Heat Treatmentmentioning

confidence: 99%

Surface Segregation of Ti in a V-4Cr-4Ti Alloy and Its Influence on the Surface Reaction Rates of Hydrogen Isotopes

et al. 2005

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The change in the chemical surface state of a V-4Cr-4Ti alloy after heat treatments in vacuum at temperatures from 573 to 1273 K was investigated by means of X-ray photoelectron spectroscopy. Before heating, the surface of the as-polished alloy was covered with a V oxide film. Diffusion of oxygen into the bulk started at around 673 K, and the alloy surface gradually became metallic. Oxygen, however, did not disappear from the surface completely. Surface segregation of Ti was observed as the temperature increased. The concentration of Ti reached 20 at% at 1273 K. No significant segregation of Cr or other impurities were observed. This surface segregation of Ti significantly reduced the surface reaction rates of H 2 and D 2 . The isotope effect on the surface reaction rates of H 2 and D 2 was not observed under the present experimental conditions.

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“…This difference in hydrogenation behavior was ascribed to the difference in surface properties between MgNi 2 and Ni. According to the theoretical models for the interaction between metals and atomic hydrogen, [18][19][20] the concentration of hydrogen in the specimen particles is determined by balance between the flux of penetrating hydrogen atoms and recombination release of hydrogen molecules. Here the influences of impurities adsorbed on the particle surfaces are quite different between penetrating process and recombination process.…”

Section: Mmentioning

confidence: 99%

“…Since the internal energy of hydrogen atoms is higher than that of molecules by 2.24 eV, the penetration flux of atoms is scarcely dependent on the concentration of surface impurities. [18][19][20] On the other hand, the recombination release is markedly retarded by surface impurities. [18][19][20] Hence, the concentration of hydrogen in the particles increases with that of surface impurities.…”

Section: Mmentioning

confidence: 99%

“…[18][19][20] On the other hand, the recombination release is markedly retarded by surface impurities. [18][19][20] Hence, the concentration of hydrogen in the particles increases with that of surface impurities. Since H 2 O was the major component of residual gas in the present apparatus as mentioned in Section 2.2, it is plausible that adsorption layer of oxygen is formed on the particle surfaces.…”

Section: Mmentioning

confidence: 99%

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Hydrogenation of MgNi<SUB>2</SUB> by Atomic Hydrogen at Elevated Temperatures

Hatano

Watanabe

2002

Mater. Trans.

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Hydrogenation of MgNi 2 by atomic hydrogen was examined at elevated temperatures. Mg 2 Ni powder was compacted into a disk and heated in vacuum at 773 K for outgassing. During this heat treatment, Mg 2 Ni was transformed into MgNi 2 by evaporation of Mg. This specimen was hydrogenated at 573, 673 and 773 K by hydrogen gas of 30 Pa and atoms produced by rf-discharge. No significant hydrogenation took place by hydrogen gas. On the other hand, the specimen was hydrogenated by the exposure to atoms at 773 K up to [H]/[M] = 0.14 within 25 ks. New peaks appeared in the diffraction pattern of Cu Kα X-rays at 2θ = 34.0, 42.0, 48.9 and 86.6 • . This observation indicated that the hydride formed was in a cubic structure.

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Hydrogen solubilisation into and permeation through wall materials

Cited by 87 publications

References 13 publications

Effects of bulk impurity concentration on the reactivity of metal surface: Sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen

Effects of bulk impurity concentration on the reactivity of metal surface: Sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen

Surface Segregation of Ti in a V-4Cr-4Ti Alloy and Its Influence on the Surface Reaction Rates of Hydrogen Isotopes

Hydrogenation of MgNi<SUB>2</SUB> by Atomic Hydrogen at Elevated Temperatures

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