Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Electromigration in liquid metals.
Rozprawy doktorskie na temat „Electromigration in liquid metals”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Electromigration in liquid metals”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Hibbs, Andrew Dennis. "Electromigration in metals and critical currents in high Tc superconductors". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603993.
Pełny tekst źródłaStreszczenie:
This thesis contains experimental and theoretical work on two highly important aspects of electric current flow in solids. In Part 1 electromigration in metals is discussed and observations of the nucleation and growth of voids in aluminium microcircuits reported. The importance of stress driven diffusional backflow is highlighted and shown to play an analogous role to work hardening during plastic flow. In the second half of Part 1, a new expression for the force exerted on the lattice ions by the electrons of a current carrying metal is derived. The analysis is shown to be applicable to the similar problem of electrical resistivity and the predicted values for both electromigration mass transport and resistivity compare favourably with other expressions in the literature, and with experiment. Part 2 contains results of magnetisation measurements on the high temperature superconductor YBa2Cu3O7. Many of the essential parameters have been measured including perhaps the first data for the pinning penetration depth and the interaction distance. The results are shown to imply that YBa2Cu3O7 contains weak links approximately 1μm apart.
2
Razmislevičienė, Ina. "Dispersive liquid-liquid microextraction for the determination of metals". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130625_092031-65110.
Pełny tekst źródłaStreszczenie:
The aim of this work was to investigate and apply new DLLME systems coupled with LA-ICP-MS and ultra-performance liquid chromatography (UPLC) techniques for the preconcentration and determination of Cr(VI), Co(II), Cu(II) ir Ni(II) ions.Šioje daktaro disertacijoje apibendrintų mokslinių tyrimų tikslas – ištirti ir pritaikyti naujus Cr(VI), Co(II), Cu(II) ir Ni(II) koncentravimo ir nustatymo metodus apjungiant dispersinę skystafazę mikroekstrakciją (DSME) su lazerinio išgarinimo induktyviai sužadintos plazmos masių spektrometrijos (LA-ICP-MS) bei ultraefektyviosios skysčių chromatografijos (UESCh) metodais.
3
Pivovarov, Eugene Preskill John P. "Aspects of non-Fermi-liquid metals /". Diss., Pasadena, Calif. : California Institute of Technology, 2002. http://resolver.caltech.edu/CaltechETD:etd-05302002-130637.
Pełny tekst źródła
4
Patty, Mark R. Montfrooij Wouter T. "Single particle dynamics in liquid metals". Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6166.
Pełny tekst źródłaStreszczenie:
Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Wouter Montfrooij. Vita. Includes bibliographical references.
5
Nakajima, Hidemasa. "Modelling of inclusion behavior in liquid metals". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65995.
Pełny tekst źródła
6
Adisa, Akintayo Oluwole. "Deposition on nanoparticulate metals at the liquid/liquid and templated interface". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498795.
Pełny tekst źródłaStreszczenie:
This thesis considers the deposition of nanoparticulate metals at the liquid/liquid and templated interfaces. It comprises an introduction to the relevant literature. The literature reviewed serves as an introduction to the preparation of nanoparticles in the solution phase, particle growth mechanisms and deposition at the liquid / liquid interface and within porous structures.
7
Vaughan, James. "Ionic liquid electrochemical processing of reactive metals". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/445.
Pełny tekst źródłaStreszczenie:
Ionic liquids (ILs) were studied as solvents for electrochemical reactions with the intent to devise metallurgical processes for Al, Mg and Ti that are less energy intensive and operate at lower temperatures than current industrial practice. Tetra-alkyl phosphonium ILs are on the low end of the IL cost spectrum and are regarded as understudied compared with imidazolium and pyridinium ILs. They are also known to be more thermally stable.
The density, viscosity and conductivity of the phosphonium ILs and metal salt-IL mixtures were measured. The conductivity of the phosphonium ILs tested were found to be roughly an order of magnitude lower than imidazolium ILs; this is attributed to the relatively large cation size and localized charge. Linear density-temperature functions are presented. The viscosity and conductivity temperature relationship was modeled using the Vogel-Tamman-Fulcher (VTF) equation.
The electrochemical window of A10341'14,6,6,610 was studied on a Pt substrate over a wide range of A1C13 concentrations using cyclic voltammetry (CV). It was found that the tetra-alkyl phosphonium cation is on the order of 800 mV more electrochemically stable than the 1-ethyl-3-methyl imidazolium (EMI+).
Cathodic and anodic polarization of Al in A1C13-[P14,6,6,6]C1 (Xmc13 = 0.67) was studied at temperatures ranging from 347 to 423 K. The Butler-Volmer equation was fitted to the plots by varying the kinetic parameters. The cathodic reaction was found to be diffusion limited and the anodic reaction is limited by passivation at lower temperatures. The overpotential required for electrodissolution of Al was found to be higher than for electrodeposition.
Aluminium was electrodeposited using both an electrowinning setup (chlorine evolution anode reaction) and electrorefining setup (Al dissolution anode reaction). The deposits were characterized in terms of morphology, current efficiency and power consumption. A variety of deposit morphologies were observed ranging from smooth, to spherical to dendritic, and in some cases, the IL was occluded in the deposit. The current efficiency and power consumption were negatively impacted by the presence of H2O and HCl present in the as-received ILs and by C12(g) generated by the anode reaction in the case of the electrowinning setup. HC1 was removed by cyclic polarization or corrosion of pure Al, resulting in current efficiencies above 90%. Aluminium was electrodeposited using the electrorefining setup with anode-cathode spacing of 2 mm at power consumption as low as 0.6 kWhr/kg-Al. This is very low compared with industrial Al electrorefining and Al electroplating using the National Bureau of Standards bath, which require 15-18 kWhr/kg-Al and 18 kWhr/kg-Al, respectively. However, due to low solution conductivity the power consumption increases significantly with increased anode-cathode spacing.
Titanium tetrachloride was found to be soluble in [P14,6,6,6]Cl and increases the conductivity of the solution. Attempts to reduce the Ti(IV) included corrosion of titanium metal, corrosion of magnesium metal powder and cathodic polarization. Despite a few attempts, the electro-deposition of Ti was not observed. At this point, titanium electrodeposition from phosphonium based ILs does not appear feasible.
8
Leclerc, Stephane Alfred Andre. "Direct liquid crystal templating of mesoporous metals". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340513.
Pełny tekst źródła
9
Clegg, Richard Edward. "Liquid-metal embrittlement of metals and alloys". Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260608.
Pełny tekst źródła
10
Bozack, Michael J. "Surface phenomena in liquid metal alloys with application to development of a liquid metal ion source of B and As /". Full text open access at:, 1985. http://content.ohsu.edu/u?/etd,76.
Pełny tekst źródła
11
Pouliquen, Benoît. "Two phase, gas liquid flow through a vertical channel". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63182.
Pełny tekst źródła
12
Sismanis, Panagiotis G. 1959. "An experimental technique to measure convection in liquid metals /". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63217.
Pełny tekst źródła
13
Fernandes, Paulo Jorge Luso. "Fatigue and fracture of metals in liquid-metal environments". Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337963.
Pełny tekst źródła
14
Tolley, M. R. "The biological treatment of liquid wastes containing heavy metals". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335844.
Pełny tekst źródła
15
Mohd, Noor Laili Rusman. "Determination of transition metals by high performance liquid chromatography". Thesis, Sheffield Hallam University, 1990. http://shura.shu.ac.uk/20176/.
Pełny tekst źródłaStreszczenie:
A simple chromatographic analysis system was developed based on dynamic ion pairing using long chain anionic modifiers with a silica reversed phase based column. The aim was to carry out simultaneous multielement quantitative as well as qualitative analysis of samples containing mixtures of transition metal ions. Among the problems encountered and solved were: metalcontamination of the eluent,finding a suitable pump for the system, minimising the noise and reducing the elution times. Detection of the separated metal ions was enabled by post-column derivatisation prior to introduction to thespectrophotometric detector. This introduced many problems as the eluent and post-column reagent stream must beproperly mixed and reacted to ensure successful detection. The design and orientation of the device used for this purpose is also critical and this was studied in detail. The role played by the various constituents of the eluent in the chromatographic separation was investigated thoroughly to enable modifications to it to be made so that thechromatographic analysis could be optimised. It wasdiscovered that retention times were greatly affected byvariations in concentration and type of anionic modifier, concentration and composition of the complexing agent in the eluent and variations in the pH of the eluent. This enabled better understanding of the retention mechanism and a retention mechanism model for a dynamically coated column was proposed. Separation of copper, lead, zinc, nickel, cobalt, cadmiumand manganese in seven minutes was achieved using a mobile phase containing sodium hexanesulphate as anionic modifier, hydrogen tartrate as complexing agent at pH 3.1, with 4-(2-pyridylazo)resorcinol (PAR) detection monitored at 510 nm. Under these conditions, limits of detection in the range of 2 - 20 p.p.b. were achieved for 20 muL injections.
16
NALLO, GIUSEPPE FRANCESCO. "Modelling liquid metals for nuclear fusion and fission reactors". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2928622.
Pełny tekst źródła
17
Wheeler, Dean Alan. "Stable crack growth during the liquid metal embrittlement of aluminum by mercury /". The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487330761217423.
Pełny tekst źródła
18
Findon, Matthew M. "Semi-solid slurry formation via liquid metal mixing". Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0721103-161140/.
Pełny tekst źródła
19
Burnard, David John. "Positron emission particle tracking of inclusions in cast liquid metals". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5708/.
Pełny tekst źródłaStreszczenie:
A greater understanding of the PEPT process in dense materials has been achieved. PEPT is dependent upon the γ-ray attenuation between a tracer particle and the detectors of a positron camera. A lower limit for the radioactivity requirement for the positron camera used, was determined. PEPT in metal casting, was verified by recovering a particle from the location it had been tracked to during an experiment. An increase in the maximum temperature used with the process was also achieved. The effectiveness of ceramic foam filters was studied, the proportion of particles which passed through filters with pore sizes ranging from 10 to 30ppi was shown. The passage of inclusions through an open topped launder was also physically studied; A new geometry for a PEPT positron camera was specifically developed. In addition to the physical experiments a computer model was written, giving some additional insight into the behaviour of particles travelling through the launder. The model shows particles within the steady state flow of an industrial launder, into which a baffle was placed in the path of both the metal and the particles. Direct comparisons between the simulation and the physical experiment were drawn.
20
Mokhtari, B., i K. Pourabdollah. "Emulsion-Liquid-Membrane Extraction of Alkali Metals by Nano-baskets". Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35137.
Pełny tekst źródłaStreszczenie:
Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclusionfacilitated
emulsion liquid membrane process. The novelty of this study is application of nano-baskets of
calixcrown in the selective and efficient separation of alkali metals as both the carrier and the surfactant.
For this aim, four derivatives of diacid calix[4]-1,3-crowns-4,5 were synthesized, and their inclusionextraction
parameters were optimized including the calixcrown scaffold (4, 4 wt%) as the carrier/
demulsifier, the commercial kerosene as diluent in membrane, sulphonic acid (0.2 M) and ammonium
carbonate (0.4 M) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing
speed (300 rpm), and initial solute concentration (100 mg/L). The results reveled that under the optimized
operating condition, the degree of inclusion-extraction of alkali metals was as high as 98-99%.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35137
21
Crawford, Jessica F. "Using room-temperature liquid metals as a new reaction environment". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232783/1/Jessica_Crawford_Thesis.pdf.
Pełny tekst źródłaStreszczenie:
When conducting a chemistry experiment, reactions are often completed in a liquid solvent. This thesis investigates the outcome of using liquid metals as a new reaction environment. Galinstan is an alloy comprised of 68.5% gallium, 21.5% indium and 10% tin that can remain a liquid at room temperature and is extremely useful due to its flexibility and conductivity. This thesis shows that liquid metals can be used to synthesise new 2D materials that catalyse oxygen production during water splitting, form new materials that can catalyse ammonia production from abundant nitrate sources and facilitate the degradation of organic dye pollutants.
22
VALERIO, DOMENICO. "Multi-physics modelling of liquid metals in Advanced Nuclear Systems". Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2970997.
Pełny tekst źródła
23
Dietz, Mark L. "The role of the interface in the kinetics and mechanism of liquid-liquid extraction". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184800.
Pełny tekst źródłaStreszczenie:
When solutions of various metal 8-quinolinolates or beta-diketonates in an organic solvent were contacted with an aqueous phase and vigorously stirred to generate a large interfacial area, a reversible decrease in the organic phase concentration of the complex was observed. The magnitude of this decrease varied with interfacial area, solvent, temperature, and the nature and concentration of the complex. Analysis of the phenomenon using the Langmuir isotherm showed that the concentration change may be explained by adsorption of significant quantities of the complexes at the increased liquid-liquid interface generated by stirring. Such adsorption was found to complicate extraction kinetics measurements using the high-speed stirring technique when the product chelate is interfacially active, distorting the absorbance/time profile from which rate constants are derived, altering the interfacial area in the reaction vessel, and displacing reactant molecules from the interface. Neutral surfactants were observed to have similar effects. Chelate adsorption was also demonstrated to affect metal ion extraction equilibria, shifting the pH 1/2 value associated with a given metal ion. The magnitude of this shift was found to depend on the concentration of the chelate, its interfacial adsorption constant, and interfacial area. Differences in the pH 1/2 shift were shown to serve as a means of separating metal ions. Studies of the rate of nickel extraction by 8-quinolinols showed that the distribution constant and interfacial activity of the ligand are important factors governing the balance between bulk and interfacial pathways in the extraction. The interfacial rate constant for a given ligand was independent of organic solvent and was typically 10 times larger than the corresponding bulk value, indicating that the interface, although essentially aqueous in character, is a more conducive medium for the reaction of the metal ion and ligand.
24
Bourget, Cyril Christian Henri. "Recovery of metals from nickeliferous laterites : liquid-liquid extraction of cobalt and nickel from acidic leachates". Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263027.
Pełny tekst źródła
25
Isler, Jeremy Payton. "Interactions of Lanthanides and Liquid Alkali Metals for "Liquid-Like" Lanthanide Transport in U-Zr Fuel". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492607350430645.
Pełny tekst źródła
26
Kimura, Koji. "Inelastic x-ray scattering study of plasmons in liquid alkali metals". 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199087.
Pełny tekst źródła
27
Goodband, John H. "Novel applications using neural networks and liquid metals in radiation therapy". Thesis, Coventry University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439109.
Pełny tekst źródła
28
Bhuiyan, Golam Mohammed. "Theoretical studies of the liquid structure and thermodynamics of transition metals". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357163.
Pełny tekst źródła
29
Foletti, Claudia <1972>. "Heavy liquid metals applications: from the nuclear to the industrial field". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/413/1/Foletti_Ph.D_thesys_HLM_technology.pdf.
Pełny tekst źródła
30
Foletti, Claudia <1972>. "Heavy liquid metals applications: from the nuclear to the industrial field". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/413/.
Pełny tekst źródła
31
Iafrati, Matteo. "Phenomenology of plasma-wall interaction using liquid metals in tokamak devices". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425247.
Pełny tekst źródłaStreszczenie:
The goal of the present thesis is to present the theoretical and experimental results concerning the use of liquid metal in tokamak devices. Most of the experimental work has been performed on FTU at the ENEA laboratories in Frascati. The main part of the work has consisted of analyzing the evolution of thermal loads, plasma contamination and plasma edge parameters variations determined by the exposure of liquid metal limiters. A radiative model is proposed to explain the vapor shield effect observed during the past experimental campaigns with the Liquid Lithium Limiter: the results of the simulations and the comparisons made with the experimental data are illustrated. Much time has been spent in the installation, debugging and exploration of two different limiters on FTU: the Cooled Lithium Limiter and the Liquid Tin Limiter. FTU was the first, and up to now unique, tokamak in the world operating with a liquid tin limiter. The results, supported by experimental data and simulations, are reported and discussed. Moreover, a comparison between lithium and tin experiments on FTU is presented. Part of the Ph.D. work has been dedicated to the study and the interpretation of the diagnostics deputy to the main plasma edge parameters measurements. Different Langmuir probes were designed and built for experiments in FTU and other devices too. The old FTU Langmuir probes acquisition system has been successfully moved to a new hardware, and a new software is now performing the data reconstruction. Another part of the work has concerned the implementation ex novo of a dedicated laboratory in Frascati focused on the liquid metal features studies, such as wettability, corrosion, and chemical-physical characteristics investigation of the fusion relevant liquid metals (lithium, gallium, and tin). A high vacuum oven was installed for this purpose, and the first test phase ended successfully. Furthermore, a small vacuum chamber was assembled allowing temperature up to 1500°C in a limited volume. This made it possible to increase the testing rate and ultimately to achieve the wetting of small-size tungsten CPS structures with both gallium and tin. In the present work an innovative tungsten coating processes, to avoid corrosion of the structural materials has been investigated. The studies conducted together with the University ”La Sapienza” and the ENEA Brasimone research center led to the validation and the realization of a solid and reliable tungsten deposit using the detonation gun machine. During the final period of the Ph.D., liquid tin samples analyses have been carried out after the plasma exposure on ISTTOK tokamak in Lisbon. The results obtained in the heat load calculation and tin effects on plasma are presented, together with a new proposal for the use of CPS-base samples. Finally, a work undertaken in collaboration with the INFN of Frascati and the CERN laboratory in Geneva is reported, regarding the possibility of using liquid lithium as a target for a particle accelerator for muon production.Nel lavoro di tesi vengono presentati i risultati degli studi e degli sperimenti sull’utilizzo di metallo liquido in macchine tipo tokamak. La maggior parte del lavoro sperimentale è stato svolto su FTU presso i laboratori ENEA di Frascati. L’evoluzione dei carichi termici, un’analisi della contaminazione del plasma dalle impurezze prodotte dai metalli liquidi ed uno studio delle tipiche variazione dei parametri di bordo sono al centro dell’elaborato. Due diversi limiter sono stati installati sul tokamak FTU: il Cooled Lithium limitered ed il Liquid Tin Limiter. FTU è stato il primo tokamak al mondo, e fin’ora unico, ad operare con un limiter di stagno liquido. I risultati riportati e discussi nella tesi, sono corroborati da dati sperimentali e confrontati con codici di simulazione. Al lettore viene presentata una comparazione nell’utilizzo dei due diversi elementi in un tokamak. Un modello radiativo è stato proposto per spiegare le oscillazioni di temperatura misurate durante gli esperimenti. Una parte del lavoro di dottorato si è soffermata sullo studio delle tipiche diagnostiche devote alla misura dei parametri di bordo: diverse sonde di Langmuir sono state disegnate e realizzate per gli esperimenti in FTU ed in altri dispositivi. Nell’elaborato si riporta il contributo alla realizzazione di un laboratorio dedicato allo studio sul metallo liquido. La finalità è quella di poter meglio comprendere e studiare le proprietà dei metalli di interesse fusionistico, quali litio, gallio e stagno, in termini di bagnabilità, corrosione e caratteristiche chimico-fisiche. Un forno da alto vuoto è stato realizzato per permettere questi studi e la prima fase di test si è conclusa con successo. Per velocizzare e semplificare la procedura bagnamento delle spugne di tungsteno è stata utilizzata una piccola camera da vuoto in grado di arrivare a 1500°C circa. Il bagnamento di strutture CPS è stato ottenuto sia con il gallio che con lo stagno liquido, ed i parametri più importanti del processo sono stati identificati. Nell’elaborato si propone una possibile soluzione al problema della corrosione da parte dello stagno. Infatti, è stato studiato un rivestimento di tungsteno per i materiali di supporto che saranno a contatto con i metalli liquidi al fine di prevenirne la corrosione. Lo studio condotto insieme all’università ”La Sapienza” ed al centro ENEA di Brasimone, ha portato alla realizzazione di un robusto, denso e coeso rivestimento di tungsteno mediante la tecnica conosciuta come Detonation Gun. Attualmente è in corso la richesta per un brevetto di processo. La ritenzione di deuterio è stata misurata su vari campioni di stagno liquido esposti al plasma di GyM. Nel trattato si sottolinea l’importanza di queste misure nella necessità di estrapolare dei dati utili ai fini progettuali di un divertore di metallo liquido per un futuro reattore. Negli ultimi mesi del dottorato è stato svolto un lavoro sul tokamak ISTTOK di Lisbona, nella tesi si riportano i risultati ottenuti dall’analisi dei carichi termici sul campione di stagno esposto, proponendo ulteriori sviluppi per gli esperimenti futuri. Per finire, si riassume un lavoro sviluppato in collaborazione con l’INFN di Frascati ed il CERN di Ginevra, riguardo la possibilità di utilizzare litio liquido come targhetta per un acceleratore di particelle. Il progetto di un acceleratore a muoni è limitato al momento dalle modalità di produzione degli stessi. I materiali convenzionali si sono dimostrati incapaci di sopportare densità di potenza come quelle necessarie per il progetto LEMMA. La proposta del target liquido è argomentata e sviluppata nell’elaborato, un lavoro preliminare di R & D è proposto.
32
Bernard, William J. "The continuous rheoconversion process Scale-up and optimization". Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-082305-102150/.
Pełny tekst źródła
33
Kumar, Vijaya S. "Studies On The Application Of Liquid Membranes For The Removal Of Dissolved Metals From Effluents". Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/134.
Pełny tekst źródłaStreszczenie:
Separation of dissolved metals from aqueous solutions using liquid membrane technology is highly advantageous owing to the degree of separation achieved, efficiency and application potential. In the present investigation four types of liquid membranes - bulk liquid membrane (BLM), emulsion liquid membrane (ELM), electrostatic pseudo liquid membrane (ESPLIM) and unified liquid membrane (ULM) have been extensively studied, for their application in extraction and concentration of dissolved metals from effluents. Experiments were conducted with various metal systems to optimize both system and process conditions and to find out the effect of various parameters on the performance of the process. Different mass transport models were proposed for each type, taking diffusional and kinetic resistances into account. Models were extended for simultaneous extraction systems and were verified by different metal-carrier experiments. Good agreement was found between the concentration profiles obtained from the models and the experimental data, thereby establishing the validity of models for all the four types of liquid membranes.
The stirred cell employed in BLM process eliminates emulsification and demulsification processes. It also provides simultaneous contact of the organic liquid membrane phase with aqueous feed and strip phases. Overall rate expressions for extraction and stripping in BLM are based on an assumed kinetic mechanism to explain the process qualitatively. It was found that the magnitude^ of diffusional and kinetic resistances determines the overall mass transfer coefficient. The relative magnitude of mass transfer coefficient, reaction rate constants and equilibrium constants enables to visualize the controlling regime of the process.
The problem of low flux rate due to high diffusion resistances, inefficient operation and exorbitant costs encountered in bulk and supported liquid membranes (SLM) are overcome in an ELM. In the ELM process, an emulsion of organic membrane phase and aqueous inner phase, is dispersed in the continuous aqueous feed phase. This gives a highly selective and ultra thin liquid film generating a large mass transfer area for separation. Experimental results on membrane instability and emulsion swelling indicate that volumetric leakage rate depends linearly on the stirring speed and that the nature of surfactant does not have any appreciable effect on emulsion swelling. A general permeation model was developed taking into account the external mass transfer around the emulsion drop, diffusion in the drop, reaction at the aqueous-organic interface, leakage of the internal phase to the external phase due to membrane breakup and emulsion swelling due to osmotic pressure difference. Model equations with appropriate boundary conditions were numerically solved by orthogonal collocation technique for a set of model parameters obtained either from known correlations or from independent experiments. Comparison of the model predictions with experimental data from the batch permeation of chromium and other metals using carrier Alamine 336 or LIX 64N, shows that the model predictions are in very good agreement with the experimental findings. Further this model can be used to simulate the effects of various experimental conditions such as metal and hydrogen ion concentrations, carrier concentration, drop diameters, etc., for similar systems.
Studies on ESPLIM were conducted with the aim of demonstrating the effectiveness of this new separation process and to develop a simple transport model for metal permeation. In the ESPLIM process, a high electrical field (3-5 kV A.C.) is used for phase dispersion. This system consists of a rectangular reactor filled with membrane solution divided into extraction and stripping cells by a centrally placed integrated type baffle which also acts as an electrode. Two more electrodes were placed in the extraction and stripping cells, where feed and strip phases are introduced from the top of the reactor. When high electrical field is applied across the electrodes, fine droplets of feed and strip are formed and are dispersed in extraction and stripping cells where simultaneous extraction and stripping occurs. The process can be viewed as simultaneous counter current extraction and stripping. The aqueous drops coalesce in the settlers at the bottom of the reactor and are removed continuously. Steady state mass transport model proposed for ESPLIM system accounts for the vertical counter-current extraction and stripping processes taking place in the extraction and stripping cells, together with the lateral transport process of the metal-complex and carrier across the two cells through the integrated baffle zone. The model equations were solved analytically to obtain concentration profiles as a function of the height of the reactor. The required parameters such as mass transfer coefficients, diffusion coefficients etc. were estimated using different correlations. Model predictions agreed remarkably well with the experimental data under various process conditions. From this investigation, it was found that ESPLIM is a simple, efficient and economical process and can be applied in a variety of situations.
Based on a suitable combination of solvent extraction, dispersion and liquid membrane technique, a new type of separation system called " Unified Liquid Membrane " was developed. The ULM unit was designed and fabricated, and experiments were conducted to evaluate its performance. The ULM is basically derived from ESPLIM by changing the reactor, baffle design and dispersion technique. Aqueous feed and strip phases were atomized using compressed air through a fine nozzle and are dispersed on either side of an integrated baffle plate that divides the reactor into extraction and stripping cells. Tapering bottom of the reactor reduces the dead volume of the liquid in the settlers and the baffle plate remarkably reduces the leakage problem as well as the resistance through the baffle. Experiments were conducted using LIX 64N and Alamine 336 as carriers for copper and chromium and / or zinc. Mass transport model proposed considers both chemical and phase equilibria in extraction and stripping cells, vertical and lateral transport of carrier and complex across the extraction and stripping cells through the baffle zone. The model equations were solved using initial conditions at the top of the reactor, and equilibrium data for extraction and stripping cells. Effect of various experimental conditions and process parameters was simulated using this model and the model predictions are found to be in excellent agreement with the experimental data. The ULM system developed in this investigation overcomes the major limitations encountered with the other types of liquid membranes while retaining all the advantages of this technology. The problem of high mass transfer resistance from bulk phase to metal permeation as in the case of BLM was eliminated by good phase dispersion. Additional resistance to mass transport from solid membrane as in the case of SLM was removed by using an integrated baffle which also avoids problems of membrane instability, pore clogging and selectivity. The complex problems of emulsification and demulsification were completely eliminated making the system much simpler and efficient. Very good phase dispersion was obtained by atomization without the need for either stirring the whole system or application of high electrical field in the reactor. The membrane liquid within the integrated baffle elements allows easy transport of different species between extraction and stripping cells while completely preventing the mixing of the two aqueous phases. The problems of leakage, swelling and occlusion were avoided due to very short residence time of the aqueous drops in the reactor. It was found that the new ULM configuration is simple, elegant, highly efficient and superior to the other types of liquid membrane systems.
34
Kumar, Vijaya S. "Studies On The Application Of Liquid Membranes For The Removal Of Dissolved Metals From Effluents". Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/134.
Pełny tekst źródłaStreszczenie:
Separation of dissolved metals from aqueous solutions using liquid membrane technology is highly advantageous owing to the degree of separation achieved, efficiency and application potential. In the present investigation four types of liquid membranes - bulk liquid membrane (BLM), emulsion liquid membrane (ELM), electrostatic pseudo liquid membrane (ESPLIM) and unified liquid membrane (ULM) have been extensively studied, for their application in extraction and concentration of dissolved metals from effluents. Experiments were conducted with various metal systems to optimize both system and process conditions and to find out the effect of various parameters on the performance of the process. Different mass transport models were proposed for each type, taking diffusional and kinetic resistances into account. Models were extended for simultaneous extraction systems and were verified by different metal-carrier experiments. Good agreement was found between the concentration profiles obtained from the models and the experimental data, thereby establishing the validity of models for all the four types of liquid membranes.
The stirred cell employed in BLM process eliminates emulsification and demulsification processes. It also provides simultaneous contact of the organic liquid membrane phase with aqueous feed and strip phases. Overall rate expressions for extraction and stripping in BLM are based on an assumed kinetic mechanism to explain the process qualitatively. It was found that the magnitude^ of diffusional and kinetic resistances determines the overall mass transfer coefficient. The relative magnitude of mass transfer coefficient, reaction rate constants and equilibrium constants enables to visualize the controlling regime of the process.
The problem of low flux rate due to high diffusion resistances, inefficient operation and exorbitant costs encountered in bulk and supported liquid membranes (SLM) are overcome in an ELM. In the ELM process, an emulsion of organic membrane phase and aqueous inner phase, is dispersed in the continuous aqueous feed phase. This gives a highly selective and ultra thin liquid film generating a large mass transfer area for separation. Experimental results on membrane instability and emulsion swelling indicate that volumetric leakage rate depends linearly on the stirring speed and that the nature of surfactant does not have any appreciable effect on emulsion swelling. A general permeation model was developed taking into account the external mass transfer around the emulsion drop, diffusion in the drop, reaction at the aqueous-organic interface, leakage of the internal phase to the external phase due to membrane breakup and emulsion swelling due to osmotic pressure difference. Model equations with appropriate boundary conditions were numerically solved by orthogonal collocation technique for a set of model parameters obtained either from known correlations or from independent experiments. Comparison of the model predictions with experimental data from the batch permeation of chromium and other metals using carrier Alamine 336 or LIX 64N, shows that the model predictions are in very good agreement with the experimental findings. Further this model can be used to simulate the effects of various experimental conditions such as metal and hydrogen ion concentrations, carrier concentration, drop diameters, etc., for similar systems.
Studies on ESPLIM were conducted with the aim of demonstrating the effectiveness of this new separation process and to develop a simple transport model for metal permeation. In the ESPLIM process, a high electrical field (3-5 kV A.C.) is used for phase dispersion. This system consists of a rectangular reactor filled with membrane solution divided into extraction and stripping cells by a centrally placed integrated type baffle which also acts as an electrode. Two more electrodes were placed in the extraction and stripping cells, where feed and strip phases are introduced from the top of the reactor. When high electrical field is applied across the electrodes, fine droplets of feed and strip are formed and are dispersed in extraction and stripping cells where simultaneous extraction and stripping occurs. The process can be viewed as simultaneous counter current extraction and stripping. The aqueous drops coalesce in the settlers at the bottom of the reactor and are removed continuously. Steady state mass transport model proposed for ESPLIM system accounts for the vertical counter-current extraction and stripping processes taking place in the extraction and stripping cells, together with the lateral transport process of the metal-complex and carrier across the two cells through the integrated baffle zone. The model equations were solved analytically to obtain concentration profiles as a function of the height of the reactor. The required parameters such as mass transfer coefficients, diffusion coefficients etc. were estimated using different correlations. Model predictions agreed remarkably well with the experimental data under various process conditions. From this investigation, it was found that ESPLIM is a simple, efficient and economical process and can be applied in a variety of situations.
Based on a suitable combination of solvent extraction, dispersion and liquid membrane technique, a new type of separation system called " Unified Liquid Membrane " was developed. The ULM unit was designed and fabricated, and experiments were conducted to evaluate its performance. The ULM is basically derived from ESPLIM by changing the reactor, baffle design and dispersion technique. Aqueous feed and strip phases were atomized using compressed air through a fine nozzle and are dispersed on either side of an integrated baffle plate that divides the reactor into extraction and stripping cells. Tapering bottom of the reactor reduces the dead volume of the liquid in the settlers and the baffle plate remarkably reduces the leakage problem as well as the resistance through the baffle. Experiments were conducted using LIX 64N and Alamine 336 as carriers for copper and chromium and / or zinc. Mass transport model proposed considers both chemical and phase equilibria in extraction and stripping cells, vertical and lateral transport of carrier and complex across the extraction and stripping cells through the baffle zone. The model equations were solved using initial conditions at the top of the reactor, and equilibrium data for extraction and stripping cells. Effect of various experimental conditions and process parameters was simulated using this model and the model predictions are found to be in excellent agreement with the experimental data. The ULM system developed in this investigation overcomes the major limitations encountered with the other types of liquid membranes while retaining all the advantages of this technology. The problem of high mass transfer resistance from bulk phase to metal permeation as in the case of BLM was eliminated by good phase dispersion. Additional resistance to mass transport from solid membrane as in the case of SLM was removed by using an integrated baffle which also avoids problems of membrane instability, pore clogging and selectivity. The complex problems of emulsification and demulsification were completely eliminated making the system much simpler and efficient. Very good phase dispersion was obtained by atomization without the need for either stirring the whole system or application of high electrical field in the reactor. The membrane liquid within the integrated baffle elements allows easy transport of different species between extraction and stripping cells while completely preventing the mixing of the two aqueous phases. The problems of leakage, swelling and occlusion were avoided due to very short residence time of the aqueous drops in the reactor. It was found that the new ULM configuration is simple, elegant, highly efficient and superior to the other types of liquid membrane systems.
35
Antipas, George. "A study of the spray forming of Al-Li alloys". Thesis, University of Surrey, 1995. http://epubs.surrey.ac.uk/843719/.
Pełny tekst źródłaStreszczenie:
The atomization and spray forming of liquid metals was studied. Melt break up algorithms were developed to predict the size distribution of the spray generated as well as secondary aspects of the atomization phenomena. In the model, which is based on the Surface Wave Formation (SWF) theory, the relative velocity between the gas and melt phase was thought to induce a sinusoidal disturbance on the surface of the melt column. Depending on the flow conditions such a disturbance could grow in amplitude and cause certain parts of the surface to be torn off the liquid column. A number of different approaches to the problem of drop disintegration were also considered. Based on experimental observations of the critical Weber number made by other authors, a criterion was formulated, which allowed the secondary break up of drops to be predicted. In addition, an analytical model originally presented by Wolf and Andersen (1965), which was intended to describe the stripping mode of secondary disintegration, was also revised and incorporated into a computer routine. Finally a comparison of the models was made against the predictions of the empirical Lubanska (1970) equation. High Speed Photography studies of a water column atomized by gas revealed that the formation of a surface wave was the prominent mechanism perturbing and finally disintegrating the column into a fine spray of drops. Phase Doppler Anemometry studies of the water/gas jet produced during the atomization of a water column indicated that there was a gradient of particle sizes across the spray. The finer fragments were found in the close proximity of the centre axis of the conical flow, with particles becoming larger in size as the distance from the centre increased. Vaporization of the water drops near the centre due to the high gas velocities should be taken into account when interpreting these results. The break up algorithms were tested against experimental data for a number of different A1 and Fe alloys with various solute elements, obtained using a close coupled atomization facility. Case studies were made for the effects of gas injection pressure, initial melt stream diameter, initial melt stream exit velocity and number of atomizing gas jets on the mean powder particle size produced. The algorithms could predict the distribution of drop sizes in space, a feature that enabled the simulation of spray forming runs and the direct comparison of the numerical predictions to experimental data. The shapes of the Al-1.6wt%Hf and the Al-1.6wt%Hf-3.2wt%Li alloy preforms and the particle distribution along the radial direction of the Al-1.6wt%Hf preform were calculated and compared favourably with experimental data. Microscopic observation of Al-1.6wt%Hf and Al-1.6wt%Hf-3.2wt%Li preforms indicated that there was a variance of particle size as well as grain size along the radial direction of the spray. The grain size was found to decrease with increasing distance from the central axis of the preform, while the radial distribution of drop diameters did not reveal a distinct trend.
36
Burris, Matthew L. "Material evaluation of liquid metal corrosion in Zn-Al hot-dip coating baths". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1400.
Pełny tekst źródłaStreszczenie:
Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 71-73).
37
Kordás, K. (Krisztián). "Laser-assisted chemical liquid-phase deposition of metals for micro- and optoelectronics". Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514266862.
Pełny tekst źródłaStreszczenie:
Abstract
The demands toward the development of simple and cost-effective fabrication methods of metallic structures with high lateral resolution on different substrates - applied in many fields of technology, such as in microelectronics, optoelectronics, micromechanics as well as in sensor and actuator applications - gave the idea to perform this research. Due to its simplicity, laser-assisted chemical liquid-phase deposition (LCLD) has been investigated and applied for the metallization of surfaces having practical importance (Si, GaAs, SiO2, Si3N4, etc.) since the beginning of the 80s. By the invention of novel substrates (polyimide, porous silicon), it was adequate to work out new precursors or just adopt old ones and optimise LCLD in order to fabricate metallic micro-patterns upon these materials for various purposes.
According to the motivations mentioned above, LCLD was utilized for the fabrication of palladium (Pd) micro-patterns on polyimide (PI), polyimide/copper flexible printed circuit boards (PCBs), fused silica (SiO2) and silicon (Si). The selective metallization of porous silicon (PS) has been carried out with nickel (Ni). Depending on the types of lasers, either the focusing (Ar+ laser beam) or diaphragm projection (KrF and XeCl excimer laser pulses) method was employed. In the course of the work, various precursors of the corresponding metals have been investigated and utilized.
In the beginning, the pyrolytic decomposition of palladium-amine complex ions ([Pd(NH3)4]2+) on PI by a scanned and focused Ar+ laser beam was optimised and discussed. Thick (up to several micrometers) and narrow (~ 10 μm) Pd conductor lines with electrical conductivity close to that of the bulk were obtained. In the continuation of these investigations, the precursor was developed further. [Pd(NH3)4]2+ was mixed with the solution of formaldehyde (HCOH) in order to induce the reduction of the metal complex ions. To our knowledge, we were the first - so far - who applied this solution and described the reaction. With the proper choice of the laser parameters, thin Pd films as catalyst layers for electroless copper plating were deposited utilizing Ar+ and excimer lasers as well. The chemically plated copper deposits - upon the obtained Pd film - have excellent electrical and good mechanical properties.
In the second part of the thesis, three practical applications (metallization of via holes drilled in PI/Cu flexible PCBs, end-mirror fabrication on single-mode optical fibers, and carbon nanotube growth on Pd activated Si and Si/SiO2 substrates) of Pd LCLD were realized. The previously presented [Pd(NH3)4]2+ and [Pd(NH3)4]2+/HCOH precursors were employed for creating the catalyst Pd layers for the carbon nanotube chemical vapor-phase deposition and for the autocatalytic electroless chemical copper plating, respectively.
Finally, a simple novel method was introduced for the area-selective metallization of PS. Since the surface of PS reduces spontaneously most metals from their aqueous solutions, it is difficult to realize localized metal deposition from liquid-phase precursors on it. We proposed the application of a stable Ni plating bath from which the metal deposits only when the PS is irradiated with photons having wavelength shorter than 689 nm, thus making possible an area-selective laser-assisted metal deposition.
The deposited metal structures and patterns were analysed by field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectrometer (EDS), by the milling and imaging modes of a focused ion beam system (FIB), optical microscopy, profilometry, resistance, and by reflectance measurements.
38
Alderman, Angela. "Extraction of metals from aqueous solution using hollow fibre supported liquid membranes". Thesis, University of Hertfordshire, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332223.
Pełny tekst źródła
39
Wiser, Travis Sloan. "Steady state heat transfer characterization of a liquid metal thermal switch". Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Summer2005/T%5FWiser%5F062205.pdf.
Pełny tekst źródła
40
Poirier, Daniel J. "On numerical methods used in mathematical modelling of phase change in liquid metals". Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5430.
Pełny tekst źródła
41
Hobbs, Philip John. "The determination of trace metals by high performance liquid chromatography with photometric detection". Thesis, University of Plymouth, 1985. http://hdl.handle.net/10026.1/2069.
Pełny tekst źródłaStreszczenie:
The importance of trace metals and their species is reviewed and it is recognised that improved methods of determination are required. High performance liquid chromatography has grown in importance as a technique, especially since the synthesis of better column packings. The adaptability of reverse phase and ion chromatography with new post-column reagents for photometric detection for the determination of transition metal cations, is discussed. Separation of divalent transition metal by high performance chromatography was improved by eluents used in column ion chromatography, new eluents were also assessed. Lactate eluents were particularly effective and tartrate, oxalate and thiomalic buffers also showed promise. Two photometric reagents, dithizone and eriochrome black T were used as post-column reagents, sensitivity and calibration characteristics are determined. A novel method of photometric detection, observes the decrease in absorbance of the metallochromic indicator used. Using lactate eluent with the Eriochrome Black T post-column detector, linear calibrations from 10 µg ml to 5 ng mlˉ¹ for cadmium, cobalt, copper, indium, iron (III), iron (II), lead, magnesium, manganese, nickel and zinc were achieved with limits of detection between 0.5 and 5 ng. The dithizone post-column realtor achieved quantitative analysis from 10 ng ml to 10 µg mlˉ¹ for cadmium, cobalt, copper, indium, lead, nickel and zinc with limits of detection for the lactate eluent between 1 and 8 ng except for lead(45 ng). Applications of the eriochrome black T detector are shown for the speciation of iron and the determination of transition metals in river water and the analysis of alloys. The separation of oxyanions is discussed with detection by a pyrocatechol violet ternary complex. The possibility of fluorescent metal detection with 8-hydroxyquinoline-5-sulphonic acid and photometric detection with a water soluble derivative of dithizone is shown.
42
Zhang, Bo, Axel Griesche i Andreas Meyer. "Use of time resolved X-Ray radiography to measure interdiffusion in liquid metals". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-190255.
Pełny tekst źródła
43
Zhang, Bo, Axel Griesche i Andreas Meyer. "Use of time resolved X-Ray radiography to measure interdiffusion in liquid metals". Diffusion fundamentals 11 (2009) 54, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14018.
Pełny tekst źródła
44
Cherne, Frank Joseph. "Calculation of transport properties of liquid metals and their alloys via molecular dynamics". Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284305.
Pełny tekst źródłaStreszczenie:
The advanced casting modeler requires accurate viscosity and diffusivity data of liquid metals and their alloys. The present work discusses the use of equilibrium and non-equilibrium molecular dynamics techniques to obtain such data without having to rely on oversimplified phenomenological expressions or difficult and expensive experiments. Utilizing the embedded atom method (EAM), the viscosities and diffusivities for a series of equilibrium and non-equilibrium molecular dynamics simulations of nickel, aluminum, and nickel-aluminum alloys are presented. A critical comparison between the equilibrium and non-equilibrium methods is presented. Besides the transport properties, structural data for the liquids are also evaluated. EAM does a poor job of describing the transport properties of nickel-aluminum alloys, particularly near the equiatomic concentration. It has been suggested that charge transfer between nickel and aluminum atoms is responsible for the discrepancy between numerical calculations and available experimental data. A modified electronic distribution function has been developed to simulate the charge transfer associated with compound formation. The effects of such a "charge transfer" modification to the embedded atom method are evaluated. The results of these simulations indicate that the embedded atom method combined with molecular dynamics may be used as a method to predict reasonably the transport properties.
45
Kazem, Navid. "Soft Multifunctional Composites Using Liquid Metal". Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1164.
Pełny tekst źródłaStreszczenie:
Progress in the fields of wearable computing, soft robotics and bio hybrid engineering depend on new classes of soft multifunctional materials that match the mechanical properties of soft biological tissue and possess high toughness, while having metal-like electrical and thermal properties.
46
Vekris, Evangellos W. "Use of the ZARM Drop Tower facility to study freezing in undercooled liquid metals". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq22414.pdf.
Pełny tekst źródła
47
Freeman, Eric J. "Heavy Fermi and non-Fermi liquid behavior, superconductivity and magnetism in f-electron metals /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3013710.
Pełny tekst źródła
48
Patel, Hamantkumar Vasudev. "The kinetics of liquid-liquid extraction of metals in a rotating diffusion cell : a rotating diffusion cell is used to study the rates of extraction of divalent transition metals by di-(2-ethylhexyl)-phosphoric acid and a sulphur analogue : a chemical-diffusion model describes the rate curves". Thesis, University of Bradford, 1988. http://hdl.handle.net/10454/5025.
Pełny tekst źródłaStreszczenie:
A rotating diffusion cell (RDC) has been used to study the kinetics of extraction of the transition metals cobalt (II), nickel (II), copper (II) and zinc (II) from sulphate solutions into either of two extractants held in n-heptane; di-(2-ethylhexyl) phosphoric acid (D2EHPA) or di-(2- ethylhexyl) dithiophosphoric acid (D2EHDTPA). The metal concentration was 10 mM and the aqueous pH was held at 4.5. The extractant concentration was varied between 0.015 to 0.4 M. In the case of cobalt extraction by D2EHPA, the metal concentration and the pH were varied Different diluents and modifiers were also studied.The rate of extraction by D2EHDTPA was found to be faster than D2EHPA. A comprehensive mathematical model, based upon established two film theory, was developed and used to describe the above experimental results. The model was also used to predict values of the important parameters. ... These values compared well with those found by other authors but using quite different experimental techniques. OS4 In the case of cobalt extraction by D2EHPA, the more polar diluents lowered the initial rate. The overall model predicts such behaviour where the rate is also dependent on the partition coefficients of the extractant. Finally, the theory of the RDC allows the prediction of the diffusion layer thicknesses, this information together with the reaction zone thickness is used to explore the influences of diffusion and chemical reaction on the overall transfer process. The diffusion processes are calculated to be the most important of the two. This is especially so for the D2EHDTPA systems.
49
Ritwik. "Measuring the viscous flow behaviour of molten metals under shear". Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6686.
Pełny tekst źródłaStreszczenie:
The flow behaviour of liquid metals (Sn, Pb and Sn-Pb eutectic) under different shearing conditions is investigated. Experiments were performed with two designs of concentric cylinder viscometers: rotating the inner cylinder (Searle) and rotating the outer cylinder (Couette). The latter technique is uncommon and the equipment was optimised with standard oils. The flow behaviour for the metals differs in the two systems. The curves of 'apparent' viscosity versus shear rate may be divided into two regimes: I. At lower shear rates (<200 s-1): a reduction of 'apparent' viscosity with shear was observed with both viscometers. It is suggested that the high density and high surface tension of the metals and eccentricity between the cylinders at low shear rates, leads to instabilities. Results at low shear rates were therefore discarded and further detailed analysis would be required for a fuller understanding of this behaviour. II. At higher shear rates: a steady, shear-independent behaviour of 'apparent' viscosity with shear rate is observed in the Couette system (upto 600 s-1) whereas in the Searle system the 'apparent' viscosity increases with shear rate (upto 2600 s-1). From hydrodynamic theory about Newtonian fluids, it is suggested that in the Searle type viscometer, the fluid is unstable and Taylor vortices are expected at low shear rates (~80 s-1). This gives rise to an increase in the 'apparent' viscosity with shear rate. Whereas, in the Couette type, the flow is more stable, resulting in a steady 'apparent' viscosity. This interpretation is consistent with liquid metals behaving as Newtonian fluids, but further research is required to confirm this. The author suggests further experiments, with the prime one being the investigation of the fluid with counter and co-rotation of the cylinders in order to observe more complex flows. The results are expected to have implications in the modelling of flow for liquid metal processes, especially the initiation of Taylor vortices under the unstable flow conditions produced by rotating the inner cylinder.
50
Krishnardula, Venu Gopal. "Transient liquid phase bonding of ferritic oxide dispersion strengthened alloys". Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Dissertation/KRISHNARDULA_VENU_19.pdf.
Pełny tekst źródła