Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 41 for “"Hydrogen diffusion"”.
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Hydrogen diffusion and trapping in electrodeposited nickel
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1989.
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Microstructure-informed modeling of hydrogen diffusion in zirconium polycrystals
… water coolant reacts with zirconium and releases hydrogen atoms that ingress into the lattice of the metal alloy. With time, hydrogen concentration exceeds its terminal solid solubility limit in zirconium, and a brittle phase known as zirconium hydride forms. This phase severely deteriorates the …
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Modeling hydrogen diffusion for solar cell passivation and process optimization
A diffusion model for hydrogen (H) in crystalline silicon was established which takes into account the charged state conversion, junction field, mobile traps, and complex formation and dissociation at dopant and trap sites. Carrier exchange among the various charged species is a "fast" process …
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Effect of microstructural constituents on hydrogen diffusion in multiphase alloys
… is a strong link between microstructure and hydrogen diffusion and embrittlement in all metallic systems, the correlation between the two is poorly documented. It is, however, sorely needed as the current research shows that by quantifying the type and density of defects along with their …
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Investigation of the delaying time of hydrogen diffusion in alpha-iron
Includes bibliographical references.
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Numerical models for simulating hydrogen diffusion and embrittlement in high strength steels
Esta tesis presenta y discute la modelización de la difusión de hidrógeno en metales como un primer paso para predecir y mitigar la fractura asistida por hidrógeno. La fragilización por hidrógeno es un fenómeno mediante el cual se degradan los metales y las aleaciones, siendo habituales los fallos …
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Electrical Resistance Studies of Hydrogen Diffusion and of Hydride Precipitation in Niobium
Diffusion of hydrogen in niobium was studied by using thermotransport to establish a concentration gradient in a periodic width modulated sample. A sensitive Kelvin double bridge allowed the kinetics of return to uniform concentration to be monitored. In undeformed Nb, the Arhennius plot exhibited …
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Velocity, temperature, and electric field measurements on a plasma-assisted hydrogen diffusion flame
A plasma-assisted hydrogen diffusion flame, denoted as a coaxial AC DBD burner, was designed and analyzed for comparisons with simulations and to better understand the coupling of the plasma and reacting flow. Emission, PLIF, and schlieren imaging of the burner revealed three distinct operating …
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Optimization of the reactive magnetron sputter deposition, and studies of hydrogen diffusion in hydrogenated amorphous silicon based materials
The applications of hydrogenated amorphous silicon in photovoltaic devices have been hindered due to two key problems: the light-induced metastable defect creation and poor doping. To improve these properties, I have chosen the reactive magnetron sputtering method for the growth of a-Si:H and its …
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Neutronic-Thermal Simulation of Micro Reactor Designs for the Purpose of Analyzing the Impact of Thermal Expansion and Hydrogen Migration in Metal Hydride Moderator
… thermal expansion and zirconium hydride-based hydrogen diffusion to the neutronic-thermal simulation of multiple heat pipe microreactor designs. Microreactors’ smaller cores are inherently characterized by more leakage than gigawatt-scale reactor cores. The inclusion of thermal expansion’s …
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Hydrogen in transition metal doped transparent conductive oxide SnO₂
… Carlo methods are used to study the behavior of hydrogen defects in doped-tin oxides. The calculated results indicate that Mo-, W-, Nb-, F-doped SnO2 are the best doped-tin oxides at reducing hydrogen solubility in their matrices. We expect these oxides also to be the best for removing hydrogen …
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Computational modeling of hydrogen embrittlement of iron aluminides
… size effect as related to the susceptibility of hydrogen embrittlement, comparative finite element modeling simulations of intergranular fracture of two iron aluminides (FA186 and FA189) were carried out. The computational simulations involved sequentially coupled stress and hydrogen diffusion …
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Hydrogen permeation in uncoated and coated X60steel
The sustainable storage and transport of hydrogen represent major challenges for the deployment of renewable energy systems, requiring a comprehensive understanding of hydrogen–material interactions in pipeline steels and effective strategies to limit hydrogen uptake. This PhD research investigates …
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Hydrogen embrittlement of an Al-4.5Zn-2.5Mg alloy
… are interpreted as indicating that a hydrogen embrittlement mechanism is operative whereby hydrogen, generated by a corrosion reaction, embrittles the alloy. Activation energy determinations have been made for stress corrosion crack growth at the free corrosion potential, and the …
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Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors
… sputtering, erosion, blistering effects, diffusion, and so on.</p> <p>The deuterium bombardment of monocrystalline tungsten was modeled by LAMMPS code using Tersoff type interatomic potential. The deuterium trapping rate, implantation depth, and stopping time in 600-2000 K tungsten …
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Coupled Elastic-Plastic Thermomechanically Assisted Diffusion: Theory Development, Numerical Implementation, and Application
A fully coupled thermomechanical diffusion theory describing the thermal and mechanically assisted mass transport of dilute mobile constituents in an elastic solid is extended to include the effects of elastic-plastic deformation. Using the principles of modern continuum mechanics and classical …
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A coupled theory for diffusion of hydrogen and large elastic-plastic deformations of metals
… coupled-theory which accounts for diffusion of hydrogen, trapping of hydrogen, diffusion of heat, and large elastic-plastic deformations of metals is developed. Our theoretical framework places the widely-used notion of an "equilibrium" between hydrogen residing in normal …
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Hydrogen desorption and absorption for activated magnesium hydride
… studied to determine the resultant effects on hydrogen desorption and absorption kinetics for potential use as a hydrogen storage material. It is found that the addition of LiBH4 in small molar ratios results in improved kinetics of the same order as those observed for mechanically milled …
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Development of a micro-FID using a diffusion flame
… (micro-FID) was developed operating with a diffusion flame with a folded flame structure. Unlike conventional FIDs, an air-hydrogen diffusion flame was developed and tested in an encapsulated structure of Quartz-Macor®-Quartz layers. Diffusion flames are generally known to be more …
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Equilibrium and diffusion studies of metal-hydrogen systems
… pertaining to equilibrium properties of hydrogen in random binary substitutional alloys at room and lower temperatures, describing both statistics and kinetics of hydrogen in them. They represent a solution to the problem of the complete Fermi-Dirac description which is physically …
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