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Analysis of the various processes downstream cathodic hydrogen charging, I: Diffusion, laboratory permeation and measurement of hydrogen content and diffusion coefficient / Jean-Louis Crolet in MATERIAUX & TECHNIQUES, Vol. 104, N° 2 (2016)
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Titre : Analysis of the various processes downstream cathodic hydrogen charging, I: Diffusion, laboratory permeation and measurement of hydrogen content and diffusion coefficient Type de document : texte imprimé Auteurs : Jean-Louis Crolet, Auteur Année de publication : 2016 Article en page(s) : 17 p. Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Charge d'hydrogène cathodique' 'Coefficient de diffusion' transitoire' 'Laboratoire perméation' 'Teneur en hydrogène' Index. décimale : 620.11 Matériaux (propriétés, résistance) Résumé : The new views of 2000 on cathodic hydrogen charging are introduced in the numerical modelling of the downstream hydrogen diffusion, and this Part I deals with artificial laboratory permeation with electrochemical measurements on a Pd coated exit face. The “true” transients and steady state are thus calculated for the concentration profiles c(x,t) and the permeation flux Jperm, as well as the permeation efficiency Ep. The former nomenclature in term of thin vs thick membranes is indeed altered by high vs low charging fluxes, or high, medium and low, or still better, very high and moderately high, and very low and moderately low. Results are then compared to the historical calculation tools based on the boundary condition of a constant surface concentration c0 at the entry face. These mathematical tools had been developed a long time ago for permeation under gaseous charging, and they are still valid in this case, but since the abandonment of the Bockris mechanism of discharge-recombination, they are basically invalid for the new cathodic charging by direct proton transfer. More generally, it is emphasised how the two charging modes are different for any subsequent transport process, and more will be addressed in Part II. Then, the totally unexpected consequences on the mechanism of sulfide stress cracking (SSC) will be addressed in Parts III and IV. Note de contenu : - INTRODUCTION : The role of time and fortuity - The "old" hydrogen - The "new" hydrogen
- NUMERICAL MODELLING : Diffusion basics - Artificial laboratory permeation - Joined measurement of the hydrogen content co and diffusion coefficient DHRéférence de l'article : 205 DOI : http://dx.doi.org/10.1051/mattech/2016007 En ligne : http://www.mattech-journal.org/articles/mattech/pdf/2016/02/mt150085.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26656
in MATERIAUX & TECHNIQUES > Vol. 104, N° 2 (2016) . - 17 p.[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 18180 - Périodique Bibliothèque principale Documentaires Disponible Analysis of the various processes downstream cathodic hydrogen charging, II : Charging transients, precharging and natural permeation / Jean-Louis Crolet in MATERIAUX & TECHNIQUES, Vol. 104, N° 2 (2016)
[article]
Titre : Analysis of the various processes downstream cathodic hydrogen charging, II : Charging transients, precharging and natural permeation Type de document : texte imprimé Auteurs : Jean-Louis Crolet, Auteur Année de publication : 2016 Article en page(s) : 16 p. Note générale : Appendices - Bibliogr. Langues : Anglais (eng) Tags : 'Charge d'hydrogène cathodique' 'Transport de Diffusion' transitoire' 'Mesure Airstream' 'Test HIC' Index. décimale : 620.11 Matériaux (propriétés, résistance) Résumé : The new views of the subject since 2000 on cathodic hydrogen charging are introduced through the numerical modelling of the downstream hydrogen diffusion, and this Part II deals with other experimental issues not covered in the laboratory permeation described in Part I: these include HIC testing of plane sheet in two-face exposure, SSC testing and cylindrical tensile specimen, necessarily imperfect quenching of precharged specimens, impossible confusion between trapping and poor degassing, and natural permeation in the field. Orders of magnitude are given for the practical application of present calculations, and the role of alloying is also mentioned, as well as that of corrosion layers. An example of what should no longer be done is also discussed, namely the re-use of all the historical calculation tools available in the literature, since they are strictly incompatible with the present views on cathodic charging. Actually, such “approximation” would range from good or fair to awfully poor, but this depends on each calculation type. The method of airstream measurement is also discussed in the light of this new modelling, as well as the basic principles of fitness-for-purpose and application specific testing for full HIC-resistance. Note de contenu : - NUMERICAL MODELLING : Plane sheet in two face exposure - Cylindrical tensile specimen - Quenching of precharged specimens - Poor degassing vs. trapping - Natural permeation in the field - Influence of corrosion layers
- CONSEQUENCES : Orders of magnitude - Role of alloying - Practical application - Airstream measurement devices - Fitness-for-purpose and application specific testingRéférence de l'article : 206 DOI : http://dx.doi.org/10.1051/mattech/2016013 En ligne : http://www.mattech-journal.org/articles/mattech/pdf/2016/02/mt150086.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26657
in MATERIAUX & TECHNIQUES > Vol. 104, N° 2 (2016) . - 16 p.[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 18180 - Périodique Bibliothèque principale Documentaires Disponible