Academic literature on the topic 'Metallic hydrides'
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Journal articles on the topic "Metallic hydrides"
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Overhauser, A. W. "LIGHT-METAL HYDRIDES AS POSSIBLE HIGH-TEMPERATURE SUPERCONDUCTORS." International Journal of Modern Physics B 01, no. 03n04 (1987): 927–30. http://dx.doi.org/10.1142/s0217979287001328.
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Light-metal hydrides, such as LiBeH 3, have a valence-electron density similar to that assumed for metallic hydrogen. If metallic hydrides in this class can be found, they may exhibit the high superconducting temperatures that have been predicted for metallic hydrogen.
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ur Rehman, Zia, Muhammad Awais Rehman, Suliman Yousef Alomar, et al. "Hydrogen Storage Capacity of Lead-Free Perovskite NaMTH3 (MT=Sc, Ti, V): A DFT Study." International Journal of Energy Research 2024 (February 28, 2024): 1–14. http://dx.doi.org/10.1155/2024/4009198.
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Hydrogen is a promising clean energy carrier, but its storage is challenging. In this study, we investigate the potential of NaMTH3 (MT=Sc, Ti, V) hydride perovskite as solid-state hydrogen storage material. Using density functional theory (DFT), we comprehensively analyze their structural, hydrogen storage, phonon, electronic, elastic, and thermodynamic properties. Mechanical stability is assessed through calculation of lattice parameters, bulk and shear moduli, Poisson’s ratio, and Young’s modulus based on elastic constants. All three hydrides were found to be stable mechanically. Furthermore, the anisotropy factor was also investigated. Results show that the investigated hydrides are brittle and metallic. Their metallic character is due to the significant interplay between phonons and electrons. We also investigated their enthalpy, entropy, free energy, Debye temperatures, and specific heat capacities to investigate thermal stability.
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Eichinger, Karl, Ladislav Havela, Jan Prokleška, et al. "Are RENiAl hydrides metallic?" International Journal of Materials Research 100, no. 9 (2009): 1200–1202. http://dx.doi.org/10.3139/146.110172.
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Werwein, Anton, Christopher Benndorf, Marko Bertmer, Alexandra Franz, Oliver Oeckler, and Holger Kohlmann. "Hydrogenation Properties of LnAl2 (Ln = La, Eu, Yb), LaGa2, LaSi2 and the Crystal Structure of LaGa2H0.71(2)." Crystals 9, no. 4 (2019): 193. http://dx.doi.org/10.3390/cryst9040193.
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Many Zintl phases take up hydrogen and form hydrides. Hydrogen atoms occupy interstitial sites formed by alkali or alkaline earth metals and / or bind covalently to the polyanions. The latter is the case for polyanionic hydrides like SrTr2H2 (Tr = Al, Ga) with slightly puckered honeycomb-like polyanions decorated with hydrogen atoms. This study addresses the hydrogenation behavior of LnTr2, where the lanthanide metals Ln introduce one additional valence electron. Hydrogenation reactions were performed in autoclaves and followed by thermal analysis up to 5.0 MPa hydrogen gas pressure. Products were analyzed by powder X-ray and neutron diffraction, transmission electron microscopy, and NMR spectroscopy. Phases LnAl2 (Ln = La, Eu, Yb) decompose into binary hydrides and aluminium-rich intermetallics upon hydrogenation, while LaGa2 forms a ternary hydride LaGa2H0.71(2). Hydrogen atoms are statistically distributed over two kinds of trigonal-bipyramidal La3Ga2 interstitials with 67% and 4% occupancy, respectively. Ga-H distances (2.4992(2) Å) are considerably longer than in polyanionic hydrides and not indicative of covalent bonding. 2H solid-state NMR spectroscopy and theoretical calculations on Density Functional Theory (DFT) level confirm that LaGa2H0.7 is a typical interstitial metallic hydride.
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Mazov, Lev. "Interplay between magnetism and superconductivity in metallic hydrogen and hydrides at high pressure." EPJ Web of Conferences 185 (2018): 08003. http://dx.doi.org/10.1051/epjconf/201818508003.
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The detailed analysis of resistive and magnetic measurements with sulfur hydrides at high pressure is performed. The hydrogen system at high pressure can exhibit ferromagnetic (FM) as well as superconducting (SC) properties with layered structure. The onset temperature of resistive transition at 200 K in metallic sulfur hydrides corresponds to magnetic (AF SDW) phase transition rather than SC one. SC transition in these sulfur hydrides occurs only when magnetic (AF SDW) phase transition is over (~ 40 K). The SC mechanism in metallic sulfur hydrides is not conventional but corresponds to Keldysh-Kopaev model characteristic for systems with coexistence of dielectric and SC pairing.
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IVANOVIĆ, NENAD, NIKOLA NOVAKOVIĆ, DANIELE COLOGNESI, IVANA RADISAVLJEVIĆ, and STANKO OSTOJIĆ. "ELECTRONIC PRINCIPLES OF SOME TRENDS IN PROPERTIES OF METALLIC HYDRIDES." International Journal of Modern Physics B 24, no. 06n07 (2010): 703–10. http://dx.doi.org/10.1142/s0217979210064320.
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Due to their extensive present, important and versatile potential applications, metal hydrides (MH) are among the most investigated solid-state systems. Theoretical, numerical and experimental studies have provided a considerable knowledge about their structure and properties, but in spite of that, the basic electronic principles of various interactions present in MH have not yet been completely resolved. Even in the simplest MH, i.e. alkali hydrides (Alk-H), some trends in physical properties, and especially their deviations, are not well understood. Similar doubts exist for the alkaline-earth hydride (AlkE-H) series, and are even more pronounced for complex systems, like transition metal-doped AlkE-H, alanates and borohydrides. This work is an attempt of explaining some trends in the physical properties of Alk-H and AlkE-H, employing the Bader analysis of the charge distribution topology evaluated by first-principle all-electron calculations. These results are related to some variables commonly used in the explanation of experimental and calculated results, and are also accompanied by simple tight-binding estimations. Such an approach provides a valuable insight in the characteristics of M-H and H-H interactions in these hydrides, and their possible changes along with external parameters, like temperature, pressure, defect or impurity introduction. The knowledge of these basic interactions and processes taking place in simple MH are essential for the design and optimisation of complex MH-systems interesting for practical hydrogen storage applications.
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Zhang, Wen Xue, Xin Hu, Xiao Bin Lin, and Cheng He. "Zr-Catalyzed Hydrogen Chemisorptions on an Al Surface." Advanced Materials Research 197-198 (February 2011): 1096–99. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1096.
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The most promising hydrogen storage materials are perhaps complex metal hydrides. Thus, a plausible first step in the rehydrogenation mechanism is proposed by simulating the reversible hydrogen storage in Zr-doped NaAlH4. It provides insight into the catalytic role of Zr atoms on an Al surface in the chemisorptions of molecular hydrogen. It is found that the diffusion of hydride species on Al-metallic phase and formation of Al hydride species is probably the key to syntheses the next products in the rehydrogenation reaction.
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Reckeweg, Olaf, Jay C. Molstad, Scott Levy, and Francis J. DiSalvo. "Syntheses and Crystal Structures of the New Ternary Barium Halide Hydrides Ba2H3X (X = Cl or Br)." Zeitschrift für Naturforschung B 62, no. 1 (2007): 23–27. http://dx.doi.org/10.1515/znb-2007-0104.
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Single crystals of the isotypic hydrides Ba2H3X (X = Cl or Br) were obtained by solid-state reactions of Ba, NaCl, NaNH2 and metallic Na, or Ba, NH4Br and Na, respectively, in sealed, silicajacketed stainless-steel ampoules. The crystal structures of the new compounds were determined by means of single crystal X-ray diffraction. Ba2H3Cl and Ba2H3Br crystallize in a stuffed anti CdI2 structure and adopt the space group P3̄m1 (No. 164) with the lattice parameters a = 443.00(6), c = 723.00(14) pm and a = 444.92(4), c = 754.48(14) pm, respectively. The hydride positions are derived by crystallographic reasoning and with the help of EUTAX calculations. The results are compared with known data for binary and ternary alkaline earth metal hydrides.
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Latroche, Michel, and A. Percheron-Guégan. "Hydrogen Storage Properties of Metallic Hydrides." Annales de Chimie Science des Matériaux 30, no. 5 (2005): 471–82. http://dx.doi.org/10.3166/acsm.30.471-482.
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Libowitz, G. G. "Metallic hydrides; fundamental properties and applications." Journal of Physics and Chemistry of Solids 55, no. 12 (1994): 1461–70. http://dx.doi.org/10.1016/0022-3697(94)90571-1.
Full textDissertations / Theses on the topic "Metallic hydrides"
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Zito, Roberta. "Development of metallic catalysts for hydrogen production from metal hydrides." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/963.
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Nowadays proton exchange membrane fuel cell (PEMFC) using hydrogen as fuel is considered as one of the most promising alternative to combustion engines due to its zero emissions. In order to operate a PEMFC successfully, a safe and convenient hydrogen storage and production system is necessary. A stabilized aqueous solution of metal hydride is considered appropriate for use as hydrogen storage material. In particular, NaBH4 is the preferred hydride due to its high hydrogen storage capacity (10.8 wt%). Moreover, sodium borohydride is non-flammable and non-toxic. The by-products of hydrolysis reaction are environmentally friendly and can be recycled in order to re-synthesizing NaBH4. Sodium borohydride reacts with water, forming 4 moles of hydrogen and 1 mol of sodium metaborate, according with the following exothermic reaction:
NaBH4 + 2H2O ¡ú NaBO2 + 4H2 + 217 KJ/mol
To inhibit the self-hydrolysis reaction, NaBH4 solution must be maintained at pH > 13. At this pH, NaBH4 solution is very stable and the hydrogen release occurs only if the solution is in contact with specific catalysts permitting the ideation of HOD (hydrogen on demand) systems.
Considering our preliminary experiments and data of literature showing that catalysts based on ruthenium metal have a good catalytic activity, for this study, ruthenium metal catalysts on different supports such as ¦Ã-Al2O3, CeO2, TiO2, activated carbon (a mineral carbon with high surface area) were prepared. We found that Ru supported on an activated carbon of mineral origin with high surface area, is more active with respect to Ru on other supports. The best performances of Ru/activated carbon were related both to the high surface area of the activated carbon and to its high chemical inertness in the strong basic environment. Considering that activated carbon (mineral carbon with surface area of 1059m2g-1) resulted the more suitable support for the reaction under study, we investigated the NaBH4 hydrolysis over Ru catalysts supported on activated carbons with different origin and morphological characteristics. The influence of two different Ruthenium precursors (RuCl3 or Ru(NO)(NO3)3) was also studied. We found that a higher surface area leads to smaller Ru nanoparticles, whereas the presence of alkali metals on the support (mainly potassium) and the use of RuCl3 as precursor (containing chlorine), promote the formation of larger Ru clusters. In this context, it was found that the best catalytic performance was obtained using the activated carbon of vegetable origin as support and Ru(NO)(NO3)3 as precursor that give Ru clusters with 3nm as diameter size.
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Abdellatief, Mahmoud. "Structural Defects in Nanotechnology: Production, Characterization, Applications: Transport Properties in Mechanically Ground Nanocrystalline Ceramics & Hydrogen Storage in Metallic Hydrides." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368929.
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Structural defects play a major role in nanotechnology as they influence most properties, thus largely motivating the special interest in studying materials at the nano scale. The present Thesis work contributes to this broad and diversified research field with emphasis on the characterization of nanocrystalline ceramic materials and their lattice defects. In particular, main efforts were addressed to develop new and more comprehensive approaches to the study of nanocrystalline powders, combining different techniques for a better and deeper understanding of materials.
The specific applications selected in this work are basically two: nanocrystalline fluorite as a promising ionic conductor and nanocrystalline magnesium hydride for hydrogen storage applications. Chapters II and III were dedicated to investigate nanocrystalline fluorite produced by two different methods: a bottom-up approach based on co-precipitation of Ca and F precursors yielding loosely bound nanocrystals, and a popular top-down approach, high energy ball milling, giving nanocrystals of comparable sizes but strongly agglomerated and densely populated with dislocations. As a major achievement reported in this part of the Thesis work, a new approach was proposed and tested for the simultaneous modelling of X-ray Diffraction (XRD) peak profiles and solid state NMR spin-lattice relaxation data. With the valuable support of Transmission Electron Microscopy (TEM), this work offers a new understanding of the complex defect structure of nanocrystalline fluorite, and is also a demonstration of the power of combining different techniques in a consistent way.
One of the most debated aspects of nanotechnology concerns the stability of the nanostructure, and the mechanisms of defect annealing and grain growth with temperature. This topic was the object of chapter V, dedicated to study the influence of lattice defects on the grain growth kinetics of nanocrystalline fluorite. This chapter was preceded by chapter IV, on the furnace recently installed at the MCX beamline for in-situ high temperature fast data collection; besides providing useful details for the in-situ study on nanocrystalline fluorite shown in the following chapter, the activity reported in chapter IV is a tangible sign of the special involvement during the Thesis work in supporting standard operation as well as development of the ELETTRA beamline MCX. The growth kinetics was studied on two samples, among those discussed in Chapter III, with comparable crystalline domain size but drastically different lattice defect content, so to highlight the role lattice defects – dislocations in this case – in the growth process.
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Last two chapters (chapter VI and VII) were dedicated to nanocrystalline magnesium hydride, and how the performance, in particular the hydrogen desorption kinetics, can be improved by adding a nanocrystalline tin oxide. Besides general aspects on phase composition of the system and hydrogen storage capability, the work also addressed the problem of obtaining activation energy values in the thermal decomposition of magnesium hydride powders, presenting an interesting review of results given by the most known and well-assessed TG-MS coupled measurements, with details on the use of different equations of the literature on thermal analysis.
Although research work can rarely be considered as finished, a sound conclusion of this Thesis work is toward the use of different characterization techniques, also within the same data analysis procedure, to support a better, and more reliable investigation of nanomaterial properties.
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Abdellatief, Mahmoud. "Structural Defects in Nanotechnology: Production, Characterization, Applications: Transport Properties in Mechanically Ground Nanocrystalline Ceramics & Hydrogen Storage in Metallic Hydrides." Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/979/1/Thesis%40Mahmoud_final.pdf.
Full textAbstract:
Structural defects play a major role in nanotechnology as they influence most properties, thus largely motivating the special interest in studying materials at the nano scale. The present Thesis work contributes to this broad and diversified research field with emphasis on the characterization of nanocrystalline ceramic materials and their lattice defects. In particular, main efforts were addressed to develop new and more comprehensive approaches to the study of nanocrystalline powders, combining different techniques for a better and deeper understanding of materials.
The specific applications selected in this work are basically two: nanocrystalline fluorite as a promising ionic conductor and nanocrystalline magnesium hydride for hydrogen storage applications. Chapters II and III were dedicated to investigate nanocrystalline fluorite produced by two different methods: a bottom-up approach based on co-precipitation of Ca and F precursors yielding loosely bound nanocrystals, and a popular top-down approach, high energy ball milling, giving nanocrystals of comparable sizes but strongly agglomerated and densely populated with dislocations. As a major achievement reported in this part of the Thesis work, a new approach was proposed and tested for the simultaneous modelling of X-ray Diffraction (XRD) peak profiles and solid state NMR spin-lattice relaxation data. With the valuable support of Transmission Electron Microscopy (TEM), this work offers a new understanding of the complex defect structure of nanocrystalline fluorite, and is also a demonstration of the power of combining different techniques in a consistent way.
One of the most debated aspects of nanotechnology concerns the stability of the nanostructure, and the mechanisms of defect annealing and grain growth with temperature. This topic was the object of chapter V, dedicated to study the influence of lattice defects on the grain growth kinetics of nanocrystalline fluorite. This chapter was preceded by chapter IV, on the furnace recently installed at the MCX beamline for in-situ high temperature fast data collection; besides providing useful details for the in-situ study on nanocrystalline fluorite shown in the following chapter, the activity reported in chapter IV is a tangible sign of the special involvement during the Thesis work in supporting standard operation as well as development of the ELETTRA beamline MCX. The growth kinetics was studied on two samples, among those discussed in Chapter III, with comparable crystalline domain size but drastically different lattice defect content, so to highlight the role lattice defects – dislocations in this case – in the growth process.
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Last two chapters (chapter VI and VII) were dedicated to nanocrystalline magnesium hydride, and how the performance, in particular the hydrogen desorption kinetics, can be improved by adding a nanocrystalline tin oxide. Besides general aspects on phase composition of the system and hydrogen storage capability, the work also addressed the problem of obtaining activation energy values in the thermal decomposition of magnesium hydride powders, presenting an interesting review of results given by the most known and well-assessed TG-MS coupled measurements, with details on the use of different equations of the literature on thermal analysis.
Although research work can rarely be considered as finished, a sound conclusion of this Thesis work is toward the use of different characterization techniques, also within the same data analysis procedure, to support a better, and more reliable investigation of nanomaterial properties.
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Li, Xianda. "Mechanical alloying Ti-Ni based metallic compounds as negative electrode materials for Ni-MH battery." Thesis, Belfort-Montbéliard, 2015. http://www.theses.fr/2015BELF0256/document.
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Les accumulateurs Ni-MH (Nickel-Métal-Hydrure) sont un sujet prometteur et largement étudié dans les recherches d’une énergie propre et durable. Trouver le matériau idéal pour l'électrode négative à haute densité volumétrique et gravimétrique est la clé pour l’application de cette technologie. Les hydrures métalliques à base de Ti-Ni ont des propriétés équilibrées entre la capacité d’hydrogène et les performances électrochimiques.L’objectif de cette thèse est d’étudier les effets de substitutions/additions d’éléments et de la mécanosynthèse sur la structure et les propriétés d’hydrogène des alliages Ti-Ni. Dans cette étude, une série d’alliages à base de Ti-Ni avec des substitutions/additions de Mg ou de Zr ont été systématiquement étudiés.Les alliages (TiNi)1-xMgx, (TiH2)1.5Mg0.5Ni, and Ti2-xZrxNi ont été synthétisés par mécanosynthèse à partir de poudres élémentaires. Dans un premier temps, l’influence du temps de broyage et les effets de substitutions/additions sur les microstructures ont été caractérisés par des techniques telles que la DRX, le MEB et le MET. Dans un second temps, les propriétés d’hydrogénation des différents alliages ont été mesurées par des réactions solid-gaz et par cyclage électrochimique.La théorie de la fonctionnelle de la densité (DFT) en utilisant le programme CASTEP a permis de calculer les enthalpies de formation afin de comparer la stabilité thermodynamique des alliages obtenus. Dans ces travaux de recherche, nous avons identifié les priorités d’alliage des ternaires Ni-Ti-Mg et Ti-Ni-Zr dans des conditions de broyage. La transformation structurale du Ti en phase CFC, induite par l’introduction d’éléments étrangers, a été mise en évidence.Les courbes PCI (Pression-Composition-Isothermes) et les capacités de décharge en fonction du nombre de cycles indiquent les propriétés d’hydrogène des alliages obtenus, y compris TiNi, Ti2Ni (amorphe), Ti-Mg et Ti-Zr<br>Ni-MH (Nickel-Metal-Hydride) batteries have been a promising and extensively studied topic among clean and sustainable energy researches. Finding the ideal material for the negative electrode with high volumetric and gravimetric densities is the key to apply this technology on broader applications. Metal hydrides based on Ti-Ni have balanced properties between hydrogen capacity and electrochemical performances in cycling.The objective of this thesis is to study the effects of element substitution/doping and mechanical alloying on the structural and hydrogen properties of Ti-Ni alloys. In this study, a series of Ti-Ni based systems with Mg or Zr doping/substitution have been systematically investigated.The metallic compounds (TiNi)1-xMgx, (TiH2)1.5Mg0.5Ni, and Ti2-xZrxNi were synthesized by mechanically alloying from elemental powders.The milling time and effects of Mg, Zr substitution/doping were studied firstly in respect of their microstructures, using characterization techniques including XRD, SEM, TEM (EDX support), followed by the hydrogen properties measurements of the samples by hydrogen solid-gas reaction and electrochemical cycling.A first principle calculation tool based on DFT (Density Functional Theory) was carried out to further investigate the enthalpy of formation in order to compare the thermodynamical stability of the obtained compounds. In the study, we have found the alloying priorities in the ternary alloys Ti-Ni-Mg and Ti-Ni-Zr under milling conditions.A structure transformation of Ti to FCC induced by foreign elements is reported and investigated. Enthalpy of formation per atom of the compounds were obtained by DFT calculations, which helped interpreting the experimental results. PCI (Pressure Composition Isotherms) curves and discharge capacities as the function of cycling numbers revealed the hydrogen properties of the obtained compounds, including TiNi, Ti2Ni (amorphous), Ti-Mg and Ti-Zr
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Andersson, Patrik, and Carl-Magnus Arvhult. "Metallic residues after hydriding of zirconium." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-125027.
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As a part of the production of nitride nuclear fuel for use in fast nuclear reactors, zirconium is hydrided followed by nitriding and mixing with uranium nitride. This work concludes a study of unwanted metallic particles present in a powder that is supposed to be a zirconium hydride. Sponge zirconium was hydrided at different temperatures and different time intervals, and the resulting hydride was milled into a powder. The powders were analyzed using SEM and XRD after which the powders were pressed into pellets for light optical microscopic study. The primary goals were determination of the structure of the particles and thereafter elimination of them. It was seen that hydriding at 500 C results in less metal particles but more experiments need to be conducted to confirm this.
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Galazzi, Rodrigo Moretto 1988. "Emprego da técnica MF-HG-AAS na determinação de estanho : análise de parâmetros analíticos e morfológicos do atomizador metálico." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248591.
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Previous issue date: 2013<br>Resumo: Nessa dissertação, otimizou-se um método para a determinação de estanho (Sn) em amostras biológicas empregando a técnica de Espectrometria de Absorção Atômica por Geração de Hidretos e Forno Metálico (MF-HG-AAS, do inglês Metallic Furnace Hydride Generation Atomic Absorption Spectrometry). Foram avaliadas algumas variáveis químicas como o tipo e concentração do carregador/diluente da solução padrão, concentração do redutor tetraidridoborato (-1) de sódio (THB) e concentração de hidróxido de sódio, bem como variáveis físicas do sistema dentre elas a vazão de carregador, proporção de acetileno:ar na chama, volume de solução injetado, vazão de argônio como gás de arraste, vazão de água no nebulizador e área total de furos no tubo metalico Inconel600®. Foi realizado um estudo do efeito de memória observado em condições de chama oxidante nas vazões de 1,5:9; 1,4:9; 1,3:9; 1,4:10; 1,4:8 e 1,5:11 L min de acetileno:ar, respectivamente. Em todas essas proporções de chama diferentes da otimizada (1,5:10 L min acetileno:ar) há efeito de memória, o que é extremamente indesejável. Após a otimização do sistema, foram realizados testes de exatidão e precisão do mesmo com os materiais PACS-2 (sedimento) e SRM 1643e (amostra de água) em que, em ambos, foi possível recuperar o Sn adicionado obtendo limites de detecção (LD) de 7,1 mg kg e 7,6 mg L, respectivamente. Um estudo com concomitantes foi realizado para avaliar se algum dos elementos em questão poderia interferir na determinação do Sn. Foram estudados como possíveis concomitantes o cobre, chumbo e zinco em três níveis diferentes. Somente o cobre, nas razões de 1:10 e 1:20 (Sn:concomitante), interferiu na detecção de Sn. Por fim, a morfologia do atomizador foi avaliada por meio da técnica de Microscopia Eletrônica de Varredura (SEM, do inglês Scanning Electron Microscopy). Mesmo após a realização de todos os experimentos envolvendo a otimização do sistema e análise das amostras, os principais constituintes do tubo metálico Inconel600® (ferro, níquel e cromo) permaneceram homogeneamente distribuídos, indicando que esses metais podem não participar da rota de atomização do Sn. Além disso, houve formação de óxidos no atomizador que, juntamente com o uso de uma chama oxidante, sugerem uma rota de atomização do Sn via formação de óxidos. Considerando os LD, bem como a exatidão e precisão por meio da recuperação de Sn obtida nas amostras, constata-se a potencialidade da MF-HG-AAS frente a outras técnicas empregadas na determinação de Sn<br>Abstract: In this work, a Metallic Furnace Hydride Generation Atomic Absorption Spectrometry (MF-HG-AAS) was optimized for tin (Sn) determination in biological samples. Chemical variables, such as the type and carrier concentration, the sodium tetrahydrideborate (-1) (THB), and the sodium hydroxide concentration, as well as physical variables, such as carrier flow-rate, ratio of acetylene and air in the flame, injection volume, argon flow-rate as carrier of stannane, water flow-rate in nebulizer and total hole area of a Inconel600® metallic furnace were evaluated. A study of a memory effect observed in oxidant flame conditions such as 1.5:9; 1.4:9; 1.3:9; 1.4:10; 1.4:8 e 1.5:11 L minof acetylene:air, respectively, was realized. In any other flame flow-rate, which the optimized flame ratio (1.5:10 L min acetylene:air) was observed a memory effect, which is very undesirable. After optimizing of the system, test of accuracy and precision were realized with the PACS-2 (sediment) and SRM 1643e (water sample) materials wherein, in both, a recovery of the Sn added to the samples was possible with limits of detection (LOD) as 7,1 mg kg and 7,6 mg L, respectively. A concomitant study was carried out for checking the interferences in the Sn determination. Copper, lead and zinc at three different levels were studied as possible concomitants. Only copper, at 1:10 and 1:20 (Sn:concomitant) ratios interfered in the determination of Sn. Finally, the morphology of the atomizer employed was evaluated through Scanning Electron Microscopy (SEM) technique. Even after carrying out all experiments involved in the optimization of the system and in the sample analysis, the main constituents of Inconel600® metallic furnace (iron, nickel and chromium) remained homogeneously distributed, indicating which these elements may not participate of the Sn atomization route. Moreover, the oxide formation in the atomizer was detected, which, together with an oxidant flame used, suggests the Sn atomization route via oxides formation. Considering the LOD, as well the accuracy and precision through the Sn recovery in the samples, the MF-HG-AAS potentially is well pointed out when it is compared to other techniques employed for Sn determination<br>Mestrado<br>Quimica Analitica<br>Mestre em Química
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Harmel, Joachim. "Betrachtungen zur Wärmebilanz von Nickel-Metall-Hydrid Batterien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1133961827450-85506.
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Heat generation plays an important role for energy storage systems like batteries in electric and hybrid vehicles. In order to investigate the thermal and electrical behaviour the nickel metal hydride batteries were exposed to cycling programs including various methods of battery cooling by flowing air. The second part of the paper describes the simulation of the temperature distribution by using finite element methods (FEM). The electric-thermal battery model was compared with results obtained from temperature measurements at four selected points during battery cycling. The results serve environmentalcareful battery employment for the general, system-oriented viewpoint of the battery condition and form the basis for energy and enviroment save used<br>Die Wärmeerzeugung spielt bei dem Einsatz von Batterien in Elektro- und Hybridfahrzeugen eine wichtige Rolle. In der Arbeit wird das thermische und elektrische Verhalten der Batterien bei der Belastung mit schnell aufeinander folgenden Höchststromladeimpulsen und -entladeimpulsen untersucht. Die Kühlung der Batterie erfolgte mit verschiedenen Methoden der Luftkühlung. Im zweiten Teil der Arbeit wird die Simulation der Temperaturverteilung mittels Finiter Element Methoden (FEM) beschrieben. Die mit einem elektrisch-thermischen Batteriemodell simulierten Temperaturen werden mit den an verschiedenen Punkten experimentell gemessenen Zelltemperaturen verglichen. Die Ergebnisse dienen zur ganzheitlichen, systemorientierten Betrachtungsweise des Batteriezustandes und bilden die Grundlage für einen energie- und umweltschonenden Batterieeinsatz
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Garica, Pedro Israel Jr. "Radical-mediated desulfonylation reactions with group 14 metallo hydrides : synthesis of (a-fluoro)phosphonates and (a-fluoro)vinyl silanes." FIU Digital Commons, 2004. https://digitalcommons.fiu.edu/etd/3524.
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The sulfone group is a well-established activating moiety important in many organic transformations. Standard procedures for desulfonylation [Al(Hg), or Na(Hg)] were ineffective for the removal of the pyridin-2-ylsulfonyl group from the α-carbon of phosphonic esters. Prompted by these results, we undertook a study for the synthesis of α-(arylsulfonyl)phosphonates, and their fluorination with Selectfluor to produce α-fluoro-α-(arylsulfonyl)phosphonates, Radical mediated hydrogenolysis of α-fluoro-α-(arylsulfonyl)phosphonates using BujSnH gave (α-fluoro)phosphonates. We observed that the yield for the desulfonylation reaction depends on the n-deficiency effect and increase in the order pyrimidinyl > pyridinyl > phenyl sulfonyl.
The (α-fluoro)phosphonates were employed as convenient precursors in the Homer-Wadsworth-Emmons (HWE) reaction to provide (α-fluoro)vinyl sulfones. The vinyl and (α-fluoro)vinyl sulfones underwent substitutive silyl and germyl- desulfonylation to yield vinyl and (α-fluoro)vinyl silanes and germanes via an addition-elimination mechanism. The vinyl tris(trimethylsilyl)silanes were employed as nucleophiles (under oxidative conditions) in palladium-catalyzed cross coupling reactions with iodobenzene and bromobenzene.
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Agresti, Filippo. "Hydrogen Storage in Metal and Complex Hydrides: from Possible Niche Applications towards Promising High Performance Systems." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426941.
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A promising alternative to hydrogen storage in high pressure cylinders and cryogenic tanks is the hydrogen storage in solid form as metal hydrides or complex metal hydrides. However, much research is still necessary in this direction. In particular, the optimal pressure and temperature of operation for the use of a hydride-based tank in a PEM fuel cell-powered vehicle should remain in the of 1-10 atm and 25-120 °C, respectively. The further difficulty is related to the weight of the storing materials, which is still too high for efficient mobile applications compared to the amount of stored hydrogen.
The work reported in this thesis deals with systems belonging to several hydride classes such as complex hydrides, interstitial metal hydrides and magnesium-based hydrides. Improvements from the point of view of thermodynamic and kinetic properties are proposed and discussed on systems almost ready for niche applications and on other very promising systems but still far from hydrogen storage applications. Among the classical interstitial hydrides-forming alloys, the interaction of hydrogen with TiCr1.78-xMnx alloys, one of the most promising for the use in high pressure-solid state hybrid tanks, has been studied. Among the Mg-based hydrides, a compacted Mg-Al-based material is proposed in order to overcome the degradation problems found during the scaling up of MgH2 as hydrogen storage medium. Concerning the complex hydrides, the kinetics improvement of the Li-Mg-N-H system by high energy ball milling processing is discussed and the problem of reversibility and slow decomposition kinetics of LiBH4 has been faced.<br>Una promettente alternativa allo stoccaggio dell’idrogeno in bombole ad alta pressione e in contenitori criogenici è lo stoccaggio dell’idrogeno allo stato solido utilizzando idruri metallici o idruri complessi. In ogni caso, molta ricerca è ancora necessaria in questa direzione. In particolare, la pressione e la temperatura di lavoro ottimali per un serbatoio da utilizzare in una vettura basata su celle a combustibili PEM dovrebbero rimanere rispettivamente negli intervalli 1-10 atm e 25-120 °C. L’ulteriore difficoltà è legata al peso dei materiali assorbenti, che è ancora troppo elevato rispetto alla quantità di idrogeno stoccata per applicazioni veicolari efficienti.
Il lavoro riportato in questa tesi riguarda sistemi appartenenti a diverse classi di idruri come idruri complessi, idruri metallici interstiziali, idruri a base di magnesio. Vengono proposti e discussi miglioramenti dal punto di vista termodinamico e cinetico apportati a sistemi ormai quasi pronti ad applicazioni di nicchia e ad altri molto promettenti ma ancora lontani da applicazioni per lo stoccaggio dell’idrogeno. Per quanto riguarda i classici idruri interstiziali, è stata studiata l’interazione dell’idrogeno con le leghe TiCr1.78-xMnx, tra le più promettenti per l’utilizzo in serbatoi ibridi ad alta pressione. Riguardo gli idruri a base di magnesio, un materiale basato su Mg-Al compattato in pastiglie viene proposto per ovviare ai problemi legati allo “scaling-up” del MgH2. Per quanto riguarda la classe degli idruri complessi, viene discusso il miglioramento delle cinetiche di assorbimento/desorbimento di idrogeno grazie al trattamento con macinazione ad alta energia e vengono affrontati i problemi della reversibilità e della lenta cinetica di decomposizione del LiBH4.
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Wanner, Martin. "Untersuchung des Langzeitverhaltens der thermodynamischen Stabilität von Metallhydriden." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9209997.
Full textBooks on the topic "Metallic hydrides"
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S, Suresh, I. M. Ward, D. R. Clarke, and Libowitz. Metallic Hydrides. University of Cambridge ESOL Examinations, 2000.
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Puls, Manfred P. Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking. Springer London, Limited, 2014.
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Puls, Manfred P. The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking. Springer, 2012.
Find full textBook chapters on the topic "Metallic hydrides"
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Banhart, John, and Clemens Ritter. "Decomposition of Ti and Zr Hydrides Studied by Neutron Diffraction." In Proceedings of the 11th International Conference on Porous Metals and Metallic Foams (MetFoam 2019). Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-42798-6_4.
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Motsnyi, F. V., M. P. Lisitsa, and S. V. Virko. "Influence of Fluctuations of Widths of Single Quantum Wells on Photoluminescence Properties in Metallo-Organic Compounds of Hydride Epitaxial GaAs /Al x Ga 1-x As Heterostructures." In Frontiers in Nanoscale Science of Micron/Submicron Devices. Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-1778-1_18.
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"Development Prospective of High-energy Combustion Agents in Propellants and Explosives." In High-energy Combustion Agents of Organic Borohydrides. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781837670017-00212.
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This chapter presents the prospective development of innovative combustion agents, including hydrogen storage composites, metal hydrides, metal borohydride compounds, ternary metal composites, and metallic-based energetic composites (MECs), which is a milestone of advanced research on high-energy combustion agents as used in chemical rocket propulsion technologies.
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BERNAS, H., A. TRAVERSE, and C. JANOT. "AMORPHOUS METALLIC HYDRIDES: A BIASED VIEW OF RECENT PROGRESS." In Amorphous Metals and Semiconductors. Elsevier, 1986. http://dx.doi.org/10.1016/b978-0-08-034334-1.50041-0.
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Winter, Mark J., and John E. Andrew. "p-Block elements." In Foundations of Inorganic Chemistry. Oxford University Press, 2000. http://dx.doi.org/10.1093/hesc/9780198792888.003.0005.
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This chapter assesses p-block elements, which are elements whose atoms have their last electron placed into a p subshell. They start with the Group 13 elements and conclude with the noble gas (Group 18) elements, at which point the final electron completes the p level. The chapter begins by explaining the trends across the periodic table: the p-block elements to the bottom left are metallic while those to the top right are non-metallic. A diagonal set of elements possess intermediate characteristics and are termed metalloids. The chapter then looks at ionic size and considers trends in the formulae of halides and oxides and in the properties of hydrides. It also studies the shapes of p-block molecules before detailing Group 13—18 elements. For p-block compounds, the Valence Shell Electron Pair Repulsion (VSEPR) method uses a simple set of electron accounting rules to carry out the prediction of the shapes of molecules.
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Weller, Mark, Jonathan Rourke, Tina Overton, and Fraser Armstrong. "The Group 13 elements." In Inorganic Chemistry. Oxford University Press, 2018. http://dx.doi.org/10.1093/hesc/9780198768128.003.0016.
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This chapter provides an overview of the essential aspects of the chemistry of the Group 14 elements which are of fundamental importance in industry and nature. This group includes carbon and silicon, both nonmetals; germanium, a metalloid; tin and lead, both metals, and the recently discovered radioactive flerovium. The chapter discusses diamond and graphite as well as other forms of carbon. It also looks at hydrides, compounds with halogen, compounds of carbon with oxygen and sulfur, and simple compounds of silicon with oxygen. Then it looks at oxides of germanium, tin, and lead. Furthermore, it tackles compounds with nitrogen. The scope of the discussion also covers carbides, silicides, extended silicon-oxygen compounds, organosilicon and organogermanium compounds, and organometallic compounds.
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Karlsson, E. B., C. A. Chatzidimitriou-Dreismann, T. Abdul-Redah, et al. "Evidence for anomalous correlations of protons in a metallic hydride." In Quantum Coherence and Decoherence. Elsevier, 1999. http://dx.doi.org/10.1016/b978-044450091-5/50073-7.
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Frey, Perry A., and Adrian D. Hegeman. "Coenzymes I: Organic Coenzymes." In Enzymatic Reaction Mechanisms. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195122589.003.0007.
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Most enzymatic reactions proceed with chemical changes that cannot be brought about by the side chains of amino acid residues. These enzymes function in cooperation with coenzymes and cofactors, which lend physicochemical potentialities not found in amino acids. Many coenzymes are organic molecules incorporating functional groups with chemical properties that enable them to facilitate reactions of certain types. These molecules bind to active sites tailored for them through evolution and equipped to assist in their coenzymatic functions. Many of these coenzymes were derived from vitamins, and in early biochemistry investigations, vitamins and coenzymes were often regarded as closely linked and even synonymous. However, vitamins such as vitamin D are more akin to hormones than to coenzymes, and in modern biochemistry, the newly discovered coenzymes are not related to vitamins and have identities independent of any nutritional origin. More than 25 biological molecules may be regarded as coenzymatic in nature. In this book, the most common coenzymes and their functions are described in two chapters, the organic coenzymes in this chapter, and the metallo-coenzymes in chapter 4. Each coenzyme and cognate enzyme form a union that allows them to act as a single catalytic entity functioning in concert to bring about a difficult chemical transformation. Each coenzyme provides the chemistry required for a class of enzymatic processes, and the mechanisms of enzymatic catalysis are often revealed through the actions of the participating coenzymes. Nicotinamide adenine dinucleotide (NAD+) is the coenzymatic form of the vitamin niacin (vitamin B1). The structural formula for NAD+ is shown in fig. 3-1 along with the biochemically reactive bonds and their importance in metabolism. NADH is the reduced form of NAD+ and is produced in the dehydrogenation of substrates. The closely related forms NADP+ and NADPH are phosphorylated at the 2′-hydroxyl group of the adenosyl moiety. NADP+ and NADPH generally participate in biosynthesis (anabolism), whereas NAD+ and NADH generally participate in biodegradative metabolism (catabolism). NAD+ and NADH were formerly known as DPN+ and DPNH, for diphosphopyridine nucleotide, and TPN+ and TPNH, for triphosphopyridine nucleotide. The most frequent function of NAD+ is as an acceptor of a hydrogen atom and two electrons, a hydride equivalent, in reactions of oxidoreductases, commonly known as dehydrogenases.
Conference papers on the topic "Metallic hydrides"
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DeFranco, Timothy, and Kevin Field. "Optimizing Additive Manufacturing of Metallic Hydrides Using Cellulose-Based Hydrogels for Advanced Reactor Applications." In Nuclear and Emerging Technologies for Space (NETS 2025). American Nuclear Society, 2025. https://doi.org/10.13182/xyz-47452.
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Hijazi, Iyad, Chaonan Zhang, and Robert Fuller. "Potentials for PdAgCu Metal Hydrides Energy Simulations." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-71494.
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Abstract Palladium hydride (Pd-H) is a metallic palladium that can absorb substantial amount of H at room temperature. Because this H absorption is recoverable, it can be utilized in a variety of energy applications. When Pd is alloyed with silver (Ag), sulfur poisoning remains a problem, but adding Ag improves Pd mechanical properties, boosts hydrogen permeability and solubility, and narrows the Pd-H system miscibility gap region. Pd alloyed with copper (Cu) has a lower H permeability and solubility compared to pure Pd and Pd-Ag alloys, but adding Cu gives better sulfur and carbon monoxide poisoning resistance and hydrogen embrittlement resistance, as well as better mechanical properties and a wider operating temperature range than pure Pd. These findings show that alloying Pd with a mix of Ag and Cu to make Pd-Ag-Cu ternary alloys improves Pd’s overall performance while also lowering its cost. Thus, in this paper, we provide the first embedded atom method potentials (EAM) for the quaternary hydrides Pd1-y-zAgyCuzHx. The EAM potentials can capture the preferred H occupancy locations, and determine the trends for the cohesive energies, lattice constants and elastic constants during MD simulations. The potentials also captured the existence of a miscibility gap for the Pd1-y-zAgyCuzHx and predicted it to narrow and disappear when Ag and Cu concentration increases, as was predicted by the experimental findings.
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Weick, Sarah, Michel Herm, Mirco Grosse, et al. "The SPIZWURZ Project - Experimental and Modeling Approaches of Hydrogen in Cladding Tubes Under Dry Storage Conditions." In 2024 31st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/icone31-136905.
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Abstract When hydrogen penetrates into cladding tubes during operation of nuclear power plants, it may affect their mechanical stability. During the dry storage of spent nuclear fuel, the initially dissolved hydrogen precipitates as hydrides in the metallic matrix. This precipitation process induces a certain stress in the zirconium structure of the cladding tube. In the framework of the SPIZWURZ project, cladding tubes are charged with hydrogen and exposed to a certain pressure — either internal or external, in order to investigate the stress influence on the hydrogen diffusion and solubility under dry storage conditions. The relevant long-term bundle test that simulated dry storage conditions with a constant cooling period of 250 days has recently ended. As described in the paper, the preliminary calculations for the temperature development and the hydride state shall be compared to the real state of the bundle after the test. Therefore, various analytical methods will help to determine relevant parameters that will be used for the fuel rod performance code TESPA-ROD from the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS), which shall be revalidated in this framework.
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Booth, Martin, and Michael Martin. "Use of the Extended Finite Element Method in the Assessment of Delayed Hydride Cracking." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63156.
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Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent failure mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure in response to concentration, temperature and hydrostatic stress gradients. As such, regions of increased hydrogen concentration develop at stress concentrating features, leading to zirconium hydride precipitation. Regions containing zirconium hydride are brittle and prone to failure if plant transient loads are sufficient. This paper demonstrates the application of the Extended Finite Element Method, or XFEM, to the assessment of the DHC susceptibility of stress concentrating features, typical of those considered in the structural integrity assessment of heavy water pressure tube reactors. The method enables the calculation of a DHC threshold load. This paper builds on the process-zone approach that is currently used to provide the industry-standard DHC assessment of zirconium alloy pressure tubes and also recent developments that have extended the application of the process-zone approach to arbitrary geometries by the use of finite element cohesive-zone analysis. In the standard cohesive-zone approach, regions of cohesive elements are situated in discrete locations where the formation of zirconium hydride is anticipated. In contrast, the use of XFEM based cohesive formulations removes the requirement to define cohesive zones a priori, thereby allowing the assessment of geometries in which the location of hydride material is not known.
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Haigh, J. "The Mechanisms of III-V Movpe and Routes to a UV-assisted process." In Microphysics of Surfaces, Beams, and Adsorbates. Optica Publishing Group, 1985. http://dx.doi.org/10.1364/msba.1985.tuc2.
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The epitaxial growth of III-V compounds by co-pyrolysis of Group III metal alkyls and Group V hydrides constitutes one application of the well-known technique of MOVPE (metallo-organic vapour phase epitaxy). Recently interest has been aroused in the possibility of photolytic enhancement of the process. Encouraging results have been reported [1,2] with GaAs. Photolysis and pyrolysis, at least in the case of the simpler metallo-organics, lead to rather similar products, and this implies that the initial stages are chemically similar and potentially compatible. The motivation for developing a photolytic/pyrolytic process derives primarily from the high spatial resolution of photon fluxes compared with conductive or radiative heat sources.
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Martin, Michael. "A Comparison of Finite Element Cohesive-Zone Modelling With the Process-Zone Approach for the Prediction of Delayed Hydride Cracking." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97077.
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Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent damage mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of the zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure towards stress concentrating features such as notches or cracks. Canadian standard CSA N285.8–10 uses a process-zone modelling approach to define a threshold stress level beyond which DHC is predicted to occur. The process-zone analysis to calculate the threshold stress level generally proceeds by representing the process-zone as a crack, the length of which is determined by the superposition of stress intensity factors obtained from handbook solutions or cracked-body finite element models. Process-zone models are a subset of the more general class of cohesive-zone models and cohesive elements are available in a number of standard finite element codes. Cohesive elements can be used to simulate the process-zone response, or indeed more complex cohesive behaviour. In this paper, the stress and displacement results from finite element based cohesive-zone modelling of a sharp crack and blunt notches of various root radii are compared with analytical process-zone solutions. The cohesive-zone results are also compared with the process-zone formulation used in CSA N285.8–10. The results show that finite element based cohesive-zone analysis can be used to replicate the process-zone results. The key benefit of finite element based cohesive-zone modelling is that it provides a framework for investigating the DHC characteristics of arbitrary hydride distributions, using readily available techniques.
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Buitrago, Jaime, Nathan A. Nissley, and Gabriel Rombado. "Verification of Fracture and Fatigue Performance of Titanium Gr. 29 Welds in Tapered Stress Joints." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83696.
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Design of a Steel Catenary Riser (SCR) requires the use of connection hardware to accommodate the bending moment that arises from the abrupt change in stiffness at the floater hang-off. Reliability of this connection hardware is of paramount importance in ultra deepwater applications (up to 3000m), especially those involving high pressure and temperature fluids. One type of such connection hardware is a metallic tapered stress joint. Because of its inherent density, strength, and stiffness, steel is not well suited for these applications due to the length and weight constraints. Titanium Gr. 29 (Ti), which is as strong as steel but lighter and more flexible, has been identified as a good material candidate for a tapered stress joint. The required length (∼40ft) and thickness (∼3.5in.) of the Titanium Stress Joint (TSJ) cannot be fabricated as a single piece due to forging size limitations. Thus, an intermediate girth weld becomes necessary. The fracture and fatigue performances in the presence of the external seawater and cathodic protection (CP) and the internal sour production with galvanic effects between the Ti and steel must be assessed to verify the service life of the stress joint. ExxonMobil has developed and initiated a Joint Industry Project to fully address the fracture and fatigue qualification of titanium welds. In particular, the project plans to establish a robust methodology for the future qualification of TSJs that parallels, to the extent possible, the qualification process currently used for SCRs. This paper discusses the primary aspects of the titanium weld qualification: (1) selection of test specimens, (2) load frequency effects on initiation and propagation lives, (3) environmental assisted cracking due to hydride formation under cathodic and galvanic conditions, (4) full-thickness small-scale fatigue, (5) size effect on fatigue, and (6) weld inspection.
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Morris, Jenny, Stephen Wickham, Phil Richardson, Colin Rhodes, and Mike Newland. "Contingency Options for the Dry Storage of Magnox Spent Fuel in the UK." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16330.
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The UK Nuclear Decommissioning Authority (NDA) is responsible for safe and secure management of spent nuclear fuel. Magnox fuel is held at some Magnox reactor sites and at Sellafield where it is reprocessed using a number of facilities. It is intended that all Magnox fuel will be reprocessed as described in the published Magnox Operating Programme (MOP) [1]. In the event, however, that a failure occurs within the reprocessing plant, the NDA has initiated a programme of activities to explore alternative contingency options for the management of wetted Magnox spent fuel. Magnox fuel comprises metallic uranium bar clad in a magnesium alloy, both of which corrode if exposed to oxygen or water. Consequently, contingency options are required to consider how best to manage the issues associated with the reactivity of the metals. Questions such as whether Magnox spent fuel needs to be dried, how it might be conditioned, how it might be packaged and held in temporary storage until a disposal facility becomes available, all require attention. During storage in the presence of water, the corrosion of Magnox fuel produces hydrogen (H2) gas, which requires careful management. When uranium reacts with hydrogen in a reducing environment, the formation of uranium hydride (UH3) may occur, which under some circumstances can be pyrophoric, and might create hazards which may affect subsequent retrieval and/or repackaging (e.g. for disposal). Other factors that may affect the choice of a viable contingency option include criticality safety, environmental impacts, security and Safeguards and economic considerations. Magnox fuel has been successfully dry-stored as intact fuel elements in CO2- and air-filled primary and secondary cells at Wylfa Power Station, UK. Storage of some fuel elements in the Wylfa secondary cells has been carried out successfully for over 25 years. Other relevant experience includes the French UNGG (Uranium Naturel Graphite Gaz) and U.S. Hanford N-Reactor spent fuels, both of which have been retrieved and dried after decades of wet storage. The dried fuels are respectively stored in sealed canisters in modular vault stores at Cadarache (CASCAD) and Hanford (Canister Storage Building). The applicability of these and other potential store designs, such as concrete and metal casks and silos, to the storage of Magnox spent fuel is discussed.
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Morris, Jenny, Stephen Wickham, Phil Richardson, Colin Rhodes, and Mike Newland. "Contingency Options for the Drying, Conditioning and Packaging of Magnox Spent Fuel in the UK." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16331.
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The UK Nuclear Decommissioning Authority (NDA) is responsible for safe and secure management of spent nuclear fuel. Magnox spent fuel is held at some Magnox reactor sites and at Sellafield where it is reprocessed using a number of facilities. It is intended that all Magnox fuel will be reprocessed, as described in the published Magnox Operating Plan (MOP) [1]. In the event, however, that a failure occurs within the reprocessing plant, the NDA has initiated a programme of activities to explore alternative contingency options for the management of wetted Magnox spent fuel. Magnox fuel comprises metallic uranium bar clad in a magnesium alloy, both of which corrode if exposed to oxygen or water. Consequently, contingency options are required to consider how best to manage the issues associated with the reactivity of the metals. Questions of whether Magnox spent fuel needs to be dried, how it might be conditioned, how it might be packaged, and held in temporary storage until a disposal facility becomes available, all require attention. A review of potential contingency options for Magnox fuel was conducted by Galson Sciences Ltd, UKAEA and the NDA. During storage in the presence of water, the corrosion of Magnox fuel produces hydrogen (H2) gas, which requires careful management. When uranium reacts with hydrogen in a reducing environment, the formation of uranium hydride (UH3) may occur, which under some circumstances can be pyrophoric, and might create hazards which may affect subsequent retrieval and/or repackaging (e.g. for disposal). Other factors that may affect the choice of a viable contingency option include criticality safety, environmental impacts, security and Safeguards and economic considerations. At post-irradiation examination (PIE) facilities in the UK, Magnox spent fuel is dried as a result of storage in air at ambient temperatures. Early French UNGG (Uranium Naturel Graphite Gaz) fuel was retrieved from pond storage at Cadarache, dried using a hot gas drying technique, oxidised and packaged in sealed canisters and placed in interim storage at the CASCAD (CASemate CADarache) facility. In the US, spent fuels including the Zircaloy clad Hanford N-Reactor fuels were cold vacuum dried and Idaho legacy aluminium clad metallic uranium fuels were hot vacuum dried; the dried fuel was then packaged in sealed and vented canisters (at Hanford and Idaho, respectively) for interim storage. With regard to conditioning and packaging, several different approaches have been reviewed, including encapsulation in cementitious grout or polymer, high-temperature vitrification or ceramicisation, and solution in acid or alkali solution followed by cementation or vitrification (without reprocessing). All of these approaches require further research in order to be evaluated and developed further for application to formerly wetted Magnox fuel. A variety of containers have been developed for the transport, storage and/or disposal of spent fuel in radioactive waste management programmes worldwide. Wetted Magnox spent fuel could be packaged in a container, with reservations about the potential formation of UH3 in a sealed environment where reducing conditions may develop. The applicability of different combinations of drying, conditioning and packaging techniques to the preparation of Magnox spent fuel for long-term storage and eventual disposal are discussed.