Dissertations / Theses on the topic 'Cementation'
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Goldsmith, Ian Robert. "Cementation in modern and ancient reefs." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6748/.
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Leetham, R. P. "Continuous cementation in particulate electrolytic cells." Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355839.
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Bernard, Lium Donovan Mujah Anak. "Biologically Induced Cementation for Soil Stabilisation." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/77105.
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Soil bio-cementation via microbially induced calcite precipitation (MICP) process generates calcite in the soil matrix through ureolysis by bacteria. This research has successfully produced effective calcite crystals; relatively larger in size than previously reported ones, and are rhombohedral in shape that favours the strategic spots of soil pore throats for precipitation. These effective calcite crystals bind sand grains together, resulting in an increase in both the strength and stiffness of the otherwise uncemented soil.
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McLemore, Thomas B. "Cementation Processes of Naturally Aged Hawaiian Calcarerous Sands." Thesis, University of Hawaii at Manoa, 2002. http://hdl.handle.net/10125/6951.
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Researchers have studied cementation of calcareous sands for decades. While cementation increases static and cyclic strengths, it also reduces skin friction on piles. Cementation of sands in their own environment varies widely with many different factors. Obtaining undisturbed samples can be difficult and costly, and laboratory reproduction of samples has become an accepted method for testing calcareous materials. The focus of this research is on understanding the processes and effects of early cementation in calcareous sand. Understanding of these processes will allow researchers the ability to better estimate light cementation effects for various types of calcareous sands. The project compared results of cyclic and static triaxial tests, cone penetrometer tests, and Scanning Electron Microscope (SEM) photographs to show the differences between two distinctly varied calcareous sands at similar densities and aged for relatively short periods of time. "Natural aging" was the baseline used for this project. All samples were saturated with distilled water and aged under a confining pressure of one atmosphere. Although not truly representative of the "natural" environment, it provides a relative baseline of how calcareous sands react in the absence of any additional cementing agent. The results of the project bring about many conclusions, as well as raising additional questions. The SEM pictures provide critical information to the project. The photographs provide a visual sense of the bonds caused from the cementation and give a visual picture of the mechanisms causing increases in static and cyclic strength. The SEM photos show two distinctly different types of bonding between the two types of sands investigated, and generally show an increase in bonding as aging time is increased. Data from all laboratory tests also show related strength increases, which can be attributed to the increase in cementation shown in the SEM photographs.xii, 101 leaves
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Long, Sarah Louise. "Aspects of cementation in recent and fossil Brachiopoda." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246325.
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Sairafi, Abdulbasit Salem. "Electro-cementation of silver using a fluidised bed." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334743.
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PINTO, HIMER ALBERTO MIELES. "NUMERICAL STUDY OF CEMENTATION PROCESS IN ERODED WELLS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29321@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Atualmente na indústria do petróleo a simulação numérica é frequentemente usada para avaliar diferentes processos através de poderosas ferramentas de software que ajudam a evitar uma pesquisa experimental, que pode ser uma tarefa cara e às vezes impraticáveis. O objetivo deste estudo é apresentar uma investigação numérica para encontrar uma melhor eficiência no processo de cimentação em poços erodidos. Neste processo, um fluido desloca um outro fluido através de um tubo com secção transversal de área variável. Ambos os fluidos podem ter um comportamento não-newtoniano. A análise é feita pela solução numérica das equações governantes, utilizando o método de volumes finitos. Estudos anteriores mostraram que os processos de deslocamento através dos poços verticais são governados principalmente pela relação de viscosidades e densidades dos fluidos, pela excentricidade do espaço anular, e pelo número de Reynolds do escoamento. Além disso, outras variáveis tais como a rotação da parede e a geometria do poço podem influenciar a eficiência do deslocamento. Dessa forma, serão analisados o efeito de alguns destes parâmetros no escoamento ao longo do poço e na eficiência de remoção nos poços erodidos, a fim de ajudar na otimização dos processos de limpeza e de remoção.
Currently in the oil industry, the numerical simulation is often used to eval-uate different processes through powerful software tools that help to prevent an experimental research in a real well, which can be an expensive and sometimes impractical task. The purpose of this study is to present a numerical investigation to find a better efficiency in the cementation process in eroded wells. In this pro-cess, one fluid displaces another through a tube with variable cross sectional area. Both fluids may have non-Newtonian behavior. The analysis is done by the nu-merical solution of the governing equations, using the finite volume method. Pre-vious studies showed that the displacement process through vertical wells are ruled primarily by the viscosity and density ratios of the fluids, the eccentricity of the annulus, and the Reynolds number. In addition, other variables such as the casing rotation and well geometry can influence the displacement efficiency. Then, the analysis of the influence of these parameters in the flow pattern through the well and removal efficiency in eroded wells will be performed, and will help to optimize the cleaning and removal processes.
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Iwabuchi, Jotaro. "The influence of cementation on liquefaction resistance of sands." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49796.
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Cohesionless sands are known to be susceptible to failure by liquefaction when they are saturated and subjected to earthquake shaking. Considerable study has been directed towards this subject over the past 20 years in recognition of the possibility of large-scale property damage or loss of life due to this type of failure. Recent evidence has shown that small degrees of cementation in a sand significantly reduce the likelihood of liquefication. However, the work to date has been limited to studies with conventional testing devices and simple loading paths. These devices are suspected of inducing premature failure in cemented soils, and are not capable of modeling the effects of multiaxial loading.
In this investigation, there were two major objectives. The first involved the development and fabrication of a new three~dimensional shear device with the capability of applying load to cemented sands with a minimum of stress concentration effects, and of using load paths which are more representative of the true effects of an earthquake than is possible in conventional equipment. The second concerned performance of a series of production tests to investigate the behavior of cemented sands under a range of earthquake loading paths. The production tests were largely performed using the new three—dimensional shear device.
The test results showed that cemented soils have more resistance to earthquake loading than previously thought since stress concentration effects in conventional testing do induce premature failure through the effects of stress concentrations. On the other hand, it was found that either cemented or uncemented sands show less resistance to earthquake loadings if multiaxial stress conditions are applied to the sample as opposed to uniaxial loadings. This is important in explaining the fact that sites with seemingly similar conditions often show different behavior, since slightly different earthquake loading pattems can cause different responses. One factor explaining differences in response is found to be the mean normal stress, which is not the same for all loadings, and plays an important role in the pore pressures developed in the soil.Ph. D.
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Nelson, Anthony. "Cementation and dolomitization of Mississippian limestones, Kentucky and Virginia." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/101249.
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The Mississippian Newman Limestone (0-30 m thick) in eastern Kentucky contains pink-staining, aquifer-related cements (up to 750 ppm Mn+2); up to 1000 ppm Fe+2; δ¹⁸ -7.5 to -6.8 per mil; δ¹³C 1.7 to -6.8) that is non-luminescent (low Fe and Mn) in the recharge area, but becomes uniformly dully luminescent downdip. This aquifer developed toward the end of Newman limestone deposition during two major regressions (Late Mississippian and Mississippian-Pennsylvanian time).
Shallow burial cementation was less common to the south-east into the Appalachian Basin, where the Mississippian limestone is up to 1000 m thick. Here, phreatic meteoric diagenesis in more distal parts of the aquifer caused high-Mg calcite and aragonite grains to be leached, while isotopically light, fine dolomite (δ¹⁸O -1.7 to -6.7 per mil; δ¹³C 2.7 to -5.3 per mil) replaced muddy carbonates in a paleomixing zone. As the aquifer evolved, low-iron, dully luminescent calcite was precipitated from reducing pore waters. With increasing burial, compaction caused spalling of ooid cortices; iron rich saddle dolomite (δ¹⁸O -5.5 to -11.2 per mil; δ¹³C 0.9 to 1.4 per mil), and moderately ferroan (purple-staining) calcite cement (0-1200 ppm Mn2+; 1000-3000 ppm Fe2+; δ¹⁸O -4.6 to -10.6 per mil; δ¹³C 2.7 to -6 per mil) precipitated in pores and fractures from waters that were increasingly dominated by warm, basinal, oil-bearing fluids expelled from dewatering Paleozoic shales. These coarse dolomites overgrew early fine dolomite of reservoirs, while the purple staining calcite filled intercrystal porosity outside of the reservoirs. At or near deepest burial, Fe-rich (blue-staining) calcite (up to 1200 ppm Mn2+; 3000-7000 ppm Fe2+; δ¹⁸O -3. 8 to -7. 8 per mil; δ¹³C 1. 8 to -1. 5 per mil) precipitated in much of the remaining void space in the limestones. During uplift of the sequence late calcite cements with decreasing Fe contents were precipitated from increasingly oxidizing fluids that penetrated the section through fractures and remaining pore spaces.M.S.
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Pina, Magnum Leo, and Magnum Leo Pina. "Reverse Engineering the Physical Chemistry of Making Egyptian Faience through Compositional Analysis of the Cementation Process." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/622834.
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The cementation process of making Egyptian faience, reported by Hans Wulfffrom a workshop in Qom, Iran, has not been easy to replicate and various views have been set forth to understand the transport of materials from the glazing powder to the surfaces of the crushed quartz beads. Replications of the process fired to 950° C and under-fired to 850° C were characterized by electron beam microprobe analysis (EPMA), petrographic thin section analysis, and scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDS). Chemical variations were modeled using thermal data, phase diagrams, and copper vaporization experiments. These replications were compared to 52 examples from various collections, including 20th century ethnographic collections of beads, glazing powder and plant ash, 12th century CE beads and glazing powder from Fustat (Old Cairo), Egypt, and to an earlier example from Abydos, Egypt in the New Kingdom and to an ash example from the Smithsonian Institution National Museum of Natural History.
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Zaheri, Shahram. "High temperature and high pressure cobalt cementation onto zinc dust." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/51855.
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Trace amounts of electrolyte cobalt during zinc electrowinning (EW) significantly decrease the current efficiency of the EW process by accelerating the parasitic hydrogen evolution reaction. The maximum tolerable level of cobalt in zinc EW can be as low as 0.1- 0.3 mg/L. The typical method to remove cobalt from zinc electrolyte, which is based on cementation onto zinc dust at approximately 85°C, is not an efficient process. It suffers from long retention times (2-3 hours) and high consumption of reagents; especially zinc dust.
The aim of the present research was to study cobalt cementation at high temperature and high pressure (HT/HP) to accelerate the rate of cobalt removal and reduce the consumption of the reagents (zinc dust and activators). Experimental variables included temperature (85-150°C), pressure (0-100 psig), zinc dust dosage, zinc dust particle size, and activators (copper and antimony).
Based on this research, the following results were obtained:
1. Increasing temperature had a significant effect on the rate of cobalt removal. The optimum temperature was found to be 125°C - temperature at which the target level of cobalt (0.1 mg/L) could be met in 20 min.
2. At 125°C and in the presence of 2.5 mg/L Sb and 45 mg/L Cu, 3.5 g/L zinc dust was found as the optimum zinc dust addition to lower cobalt concentration from the initial level of 15 mg/L to below 0.1 mg/L.
3. Smaller zinc particles showed better cobalt removal results, but the cement redissolution was also more severe with these particles.
4. The role of Sb in the activation system was more important than Cu. However, the best result in terms of the rate and extent of cobalt removal was achieved when both of the activators were added to the solution together.
5. As expected, increasing the overhead pressure of N₂ (tested at 85°C) did not alter the cobalt removal profile greatly. Also, the effect of increasing the partial pressure of H₂ (tested at 125°C, and above the amount generated in situ by the reaction) on cobalt removal was negligible.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Nelson, Amy. "Novel activators in cobalt removal from zinc electrolyte by cementation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0028/MQ50646.pdf.
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Nelson, Amy. "Novel activators in cobalt removal from zinc electrolyte by cementation." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21317.
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In the electrolytic production of zinc, cobalt is removed from zinc electrolyte by cementation with zinc dust Prior to electrowinning. Although the thermodynamics for this reaction are favourable, kinetic barriers to cobalt reduction render the method impractical unless activators such as antimony or arsenic in conjunction with copper are used. There is a large body of work studying the effect of these additives, yet the mechanism by which they act is still poorly understood. Moreover, regardless of the beneficial effect of the activators, from time to time the process fails to meet the target level of 0.1 mg/L cobalt in the purified electrolyte, with negative consequences in the electrowinning operation. Even when the target conditions are met, zinc dust consumption is excessively high: satisfactory operation requires up to 300 times the stoichiometric amount of zinc dust.In the present work the role of the antimony/copper activators was investigated in a batch cementation process using synthetic electrolyte. The objectives were to study the fundamentals of cobalt cementation in zinc sulfate electrolyte with conventional additives, to clarify the action of additives and their role in cementation, and to identify and test novel additives. (Abstract shortened by UMI.)
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Quinn, Oliver F. "Fault controlled fluid flow and quartz cementation in porous sandstones." Thesis, University of Edinburgh, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543852.
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Quartz cement is a major culprit of porosity and permeability loss in deeply buried sandstone hydrocarbon reservoirs. A major debate is whether quartz cement is entirely internally derived or if fluid flow and mass transfer can import silica for quartz cementation. Two Late Jurassic normal faults are exposed within the aeolian (U. Permian) Hopeman Sandstone, onshore within the Inner Moray Firth basin, UK North Sea. The Clashach Fault has a throw <50m. The Burghead Fault has a throw of>100m. The faults crop out within the Hopeman Horst on the southern margin of the 50km wide, 5km deep, half-graben basin. Maximum burial depth of the Hopeman Sandstone within this horst block is 1.5-2.4km. Quartz cementation is asymmetric across the fault planes. Moving through the footwall of the Clashach Fault toward the fault plane, quartz cement volume increases from 9% at 31.7m to a maximum of 26.5% at 13.8m from the plane. From 13.8m to 0.5m from the fault plane authigenic quartz volume decreases from 26.5% to 4.2% at 0.5m. In this zone carbonate cement, which later dissolved, reduced the space available for quartz precipitation. The hanging wall contains mean 4% authigenic quartz. Porosity displays an inverse relationship to quartz cement. Footwall porosity increases from 10% at 13.8m from the fault plane to 18.6% at 31.7m. From 13.8m-0.5m porosity varies inversely with the volume of quartz cement in each sample. Hanging wall mean porosity is 24.5%. Footwall intergranular volume decreases from a maximum of 32% at 13.8m to 28% at 31.7m. At the Burghead Fault, footwall authigenic quartz volume increases moderately from 24.5% at 13m from the fault plane to 29% at 0.5m from the fault plane. Porosity displays an increase from 2.3% at 0.5m to 6.1% at 13m. Permeability decreases from 100-1000mD in poorly cemented hanging wall sandstone to <1mD in extensively quartz cemented sandstones in the footwalls of both faults. Footwall intergranular volume is consistently >30% in the Burghead Fault footwall. Fluid inclusions within footwall quartz overgrowths are single phase, aqueous, indicating cement precipitation <60°C. Quartz cemented microfracture fluid inclusion trails, generated during fault movement, contain 2-phase (L+V) aqueous inclusions with mean homogenisation temperature of 166°C, recording the presence of hot fluids in the sandstone at the time of faulting. Ion microprobe analysis of quartz overgrowth oxygen isotope values for footwall cements around the Clashach Fault shows a linear increase of 8180 values with increasing distance from the fault plane from +17.9960 at 4.2m to +20.8%o at 30.8m. In quartz cements in the footwall of the Burghead Fault, 5180 rises from +17.53% at 0.1m from the fault plane to a consistent range of +19.1%o to +19.596o up to 14m distant. Hanging wall cements have a mean 6180 +23.8960 with range of 6180 +20.1ß'w to +25.09'. 0. An isotopic profile across a single quartz cemented deformation band shows 00 is a minimum mean of +20.7%o. Oxygen isotope and fluid inclusion data records quartz cementation from hot basinal fluids which entered the Hopeman Sandstone adjacent to fault planes. This fluid cooled and mixed with Jurassic meteoric porefluids, precipitating quartz cement at a burial depth of <1.25km. Siliceous fluids were sourced from sediment compaction following Late Jurassic extension in the basin and were expelled up-dip toward the basin margin. Fluid flow was locally focused through the Hopeman Horst, which acted as an exit point for regional fluid expulsion. Within the horst block advecting fluid flow was focused into basinward footwalls by the low permeability vertical fault planes. This was aided by an enhanced reduction in fault permeability by quartz cementation of deformation bands at shallow burial (500m
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Bravo, de Nahui Flora. "Mass transfer behaviour for a packed bed copper cementation system." Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234559.
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Jacquet, Philippe. "Cementation basse pression des aciers developpement d'un capteur de suivi." Paris, ENSAM, 1998. http://www.theses.fr/1998ENAM0008.
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Bien que la cementation basse pression possede des avantages indeniables par rapport a la cementation gazeuse atmospherique, notamment son absence d'oxydation interne, son developpement est freine par l'absence de moyen de controle. Le capteur que nous avons mis au point permet d'etudier la diffusion du carbone a travers une membrane de fer. La face amont de la membrane est exposee a une atmosphere carburante tandis que sa face aval est balayee par une atmosphere decarburante. L'analyse par un catharometre de la composition du gaz provenant de la face aval nous renseigne sur le flux de carbone qui penetre dans l'acier. Cette technique nous a permis de montrer que tant que le gaz possede un pouvoir carburant suffisant pour saturer la surface, on atteint plus ou moins rapidement un etat stationnaire. Si l'atmosphere est fortement surcarburante, on observe une sursaturation en carbone de la membrane se traduisant par un pic de vitesse superieur a la vitesse obtenue en regime stationnaire. Dans les deux cas, la vitesse de diffusion est l'etape regulatrice. Si l'on baisse le pouvoir carburant de l'atmosphere, on montre que c'est l'apport de carbone qui devient l'etape limitante.
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Shi, Liangyu. "Influence of artificial weak cementation on loose silty sand behavior /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20SHI.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 163-170). Also available in electronic version. Access restricted to campus users.
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Garcia, Diana Rute Santos. "Cimentação adesiva em prótese fixa." Master's thesis, [s.n.], 2014. http://hdl.handle.net/10284/4761.
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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina DentáriaIntrodução: O processo de cimentação no decorrer da reabilitação com prótese fixa é uma etapa de importância crucial e exige a execução da técnica cuidadosa e apresenta grande diversidade de materiais, pelo que é de extrema importância o domínio e conhecimento destes materiais e técnicas pelo Médico Dentista de forma a obter o melhor resultado possível e uma reabilitação duradora. Neste contexto a cimentação adesiva apresenta-se como uma técnica inovadora e como alternativa que pode ser pertinente no dia-a-dia do consultório dentário, daí a importância do conhecimento desta técnica, suas vantagens e desvantagens, suas implicações, por parte do operador, no caso, do médico dentista. Objetivo: O objetivo desta monografia foi realizar uma revisão da literatura e aprofundar conhecimentos sobre a técnica de cimentação adesiva, as suas vantagens e desvantagens, propriedades físicas, capacidade de adesão ao substrato, integridade marginal, biocompatibilidade destes cimentos e ainda o desempenho e aplicabilidade clínica. Materiais e Métodos: Foi realizada a pesquisa sobre a literatura relevante em quatro bases de dados, Pubmed(medline), Scielo, B-on e Google Académico relativamente ao tema proposto, com o intuito de recolher o máximo de informação sobre o mesmo, com um intervalo temporal dos últimos dez anos e com as seguintes palavras-chave: “adhesive cementation”, “cementation in fixed prothesis”, “cimentação de coroas”, “cimentação adesiva de restaurações indiretas”, “cimentação adesiva de pontes”, “cimentos prótese fixa”. Os artigos foram selecionados segundo o seu rigor científico e interesse para o tema, de entre aqueles que foi possível ter acesso. Conclusões: A diversidade de materiais e técnicas para cimentar em prótese fixa fazem com que o médico dentista tenha permanentemente de acompanhar a evolução de materiais e das técnicas inerentes ao processo de cimentação pois a escolha do cimento e da técnica mais adequada para cada caso clínico ditará o sucesso e a durabilidade da restauração. Assim, sendo que a técnica adesiva se apresenta como um procedimento mais recente e uma alternativa viável em vários casos, é extremamente válido o estudo e o conhecimento mais aprofundado desta técnica e dos matérias com ela relacionados para que possa ser utilizado no âmbito clínico do dia-a-dia. Introduction: The cementation process in the course of rehabilitation with fixed prosthesis is a crucial step and requires the execution of careful technique and presents great diversity of materials, so it is of utmost importance and the domain knowledge of these materials and techniques by way of Dentist to obtain the best possible result and a durable rehabilitation. In this context adhesive cementation presents itself as an innovator and as an alternative technique that can be relevant in the day-to-day dental office, hence the importance of knowledge of this technique, its advantages and disadvantages, its implications for the operator, in this case the dentist. Objective: The aim of this thesis was to conduct a literature review and deepen knowledge about the adhesive cementation technique, its advantages and disadvantages, physical properties, ability to adhere to the substrate, marginal integrity, biocompatibility of these cements and yet the performance and clinical applicability. Materials and methods: Research on relevant literature was conducted in four databases, Pubmed (Medline), SciELO, B-on and Google Scholar regarding the proposed theme, in order to gather as much information about it, with a time interval of last ten years and with the following keywords: "adhesive cementation", "cementation in fixed prothesis", "cementation of crowns", "adhesive cementation of indirect restorations", "adhesive cementation of bridges", "cements fixed prosthesis." Articles were selected according to their scientific rigor and relevance to the theme, among those who could have access. Conclusions: The diversity of materials and techniques to cement in fixed prosthodontics make the dentist has permanently monitor the evolution of materials and techniques inherent in the cementing process as the choice of cement and the most appropriate technique for each clinical case will dictate the success and the durability of the restoration. Thus, with the adhesive technique is presented as a more recent procedure and a viable alternative in many cases is extremely valuable study and deeper understanding of this technique and the materials related to it so it can be used in the clinical context of the day -to-day.
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Da, Fontoura Luiza. "Deposition of Copper Nanoparticles on 2D Graphene NanoPlatelets via Cementation Process." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3164.
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The main goal of this thesis is to deposit metal particles on the surface of 2D nanoplatelets using a controlled cementation process. As a proof of concept, copper (Cu) and Graphene Nanoplatelets (GNP) were chosen as the representative metal and 2D nanoplatelets, respectively. Specific goals of this study include depositing nanometer scale Cu particles on the surface of GNP at a low concentration (approximately 5 vol.%) while maintaining clustering and impurities at a minimum. Parametric studies were done to attain these goals by investigating various metallic reducer types and morphologies, GNP surface activation process, acid volume % and copper (II) sulfate concentrations. Optimal conditions were obtained with Mg ribbon as a reducer, 3 minutes of activation, 1 vol.% of acetic acid and 0.01 M CuSO4. The GNP-Cu powder synthesized in this work is a precursor material to be consolidated via spark plasma sintering (SPS) to make a nacre-like, layered structure for future studies.
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Felce, Graham Peter. "Lattice-Boltzmann modelling of oolitic grainstones : effects of cementation and dissolution." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551300.
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Using the lattice-Boltzmann method, simulations of fluid flow have allowed the effects of moldic dissolution and cementation on porosity and permeability to be studied. Moldic dissolution was simulated by the removal of whole and partial spheres to generate vugs and uniform cement by increasing the radius of the spheres so they coalesce. For an uncemented domain, the evolution effects of increasing moldic dissolution showed that the permeability is initially controlled by the intergranular porosity and the moldic pores are essentially isolated. As porosity increases, with approximately 9% dissolution the moldic vugs start to form connections across the domain (percolation) which agrees with existing empirical relationships. The permeability upon percolation is dominated by the connected pore-space and controlled by the moldic porosity which agrees with other work on field and simulation studies of carbonate rock fabrics. With increasing cementation, the sphere packs show consistent decreases in permeability as porosity is occluded and correlates well to existing analytical solutions of coalesced sphere packs and empirical relationships. With the addition of moldic porosity, which leaves a cement shell intact, initial permeability is controlled solely by the intergranular porosity until percolation occurs and then connected moldic porosity dominates. It was found that connected moldic porosity and intergranular permeability can be treated as separate additive contributions an allow data sets of contrasting sphere arrangements to be correlated. Partial moldic dissolution was found to represent an earlier stage of dissolution that leads to the porosity and permeability of values seen for the whole-sphere dissolution. Modification of the cement by adding in holes reconnects the two pore systems and gives an automatic 54% permeability increase that occurs when a small connection is made for just a 1 % removal of cement. This study highlights the importance of the controlling pore type and the petrophysical property of pore-throat diameter. An additional field study of carbonate rock samples collected from Eleuthera, Bahamas allowed rocks to be reconstructed using micro-CT. Simulations of fluid flow of these samples and a quantitative image analysis of the micro-CT samples indicates that permeability can be effectively described and characterised by percentage contributions of pore-length to porosity, pore-area, a macropore shape factor and the number of data points measured in the sample.
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Milstone, Barry Scott. "Effects of nonhomogeneous cementation in soils on resistance to earthquake effects." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/77896.
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Small amounts of cementation in a sand increase its ability to sustain static and dynamic loads, even in a liquefaction type environment. This has been shown in previous research examining the behavior of both naturally cemented and artificially prepared samples.
Cemented sands are present in many parts of the world and can be caused by either a variety of cementing agents or by cold welding at points of grain contact. They are generally quite difficult to sample, but artificially cemented sands have been shown to aptly model the behavior of natural materials, and allow for better test controls. Consequently, artificial samples were used exclusively for the present investigation which has three major objectives: to investigate the effects of a weakly cemented lens within a stronger mass; to determine how cementation affects the volume change characteristics of statically loaded samples; and, to describe the pore pressure generation of sands subjected to cyclic loading.
Prior to commencing the test program, a number of index tests were performed on the uncemented and cemented sand used during the laboratory investigation. It was revealed that cementation leads to increased void ratios which distort relative density calculations used to compare cemented and uncemented samples of similar dry unit weight. The practice of identifying samples by dry unit weight was adopted for this report.
Static triaxial compression tests were performed on 17 samples. Test results indicate that although the magnitude of volumetric strain at failure does not seem to be dictated by the level of cementation, there is a relationship with cementation and the rate of volume change at failure. A weak lens was seen to lower the static strength of the stronger mass. 26 stress controlled cyclic triaxial tests revealed that a weak lens lowers the liquefaction resistance of the stronger mass. The cyclic strength of the nonhomogeneous material, however, is higher than the independent strength of the weak lens. A weak lens has greater influence at relatively higher levels of cyclic stress. Pore pressure generation in cemented sands are seen to be controlled by strain. At shear strain levels below about 1%, cemented sands behave similarly to uncemented sands with pore pressures increasing more rapidly beyond that amount of strain. Consequently, pore pressure development during cyclic loading is described by a broken-back curve which is defined in the early stages by existing empirical relationships for uncemented sand. Pore pressure prediction may then be achieved using an equation for cemented sand, such as that developed in the present work.Master of Science
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Kung, Si-Cheng. "Fundamental study of aluminizing of iron by using pack cementation technique /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487322984316282.
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Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Thesis, Jiang, Xiong (1987) Electrochemical studies on the cementation of copper and cobalt with zinc. PhD thesis, Murdoch University, 1987. https://researchrepository.murdoch.edu.au/id/eprint/118/.
Full textAbstract:
The work described in this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
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Jiang, Xiong. "Electrochemical studies on the cementation of copper and cobalt with zinc." Murdoch University, 1987. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060816.135721.
Full textAbstract:
The work described i n this thesis deals mainly with a fundamental study of two cementation reactions, i.e., Cu(II)/Zn and Co(II)/Zn, using the electrochemical techniques of linear potential sweep voltammetry, cyclic vol tammetry, chronopotentiometry (stripping), capacitance measurements,ring current measurements and impedance spectroscopy. In addition, solution analysis, x-ray diffraction and scanning electron microscopy were
employed to achieve a better understanding of the kinetics and mechanisms of the two cementations. The half reactions of the two systems were also investigated as an essential part of the whole study. Of the two systems investigated, the Cu(II)/Zn system, was mainly used as a reference system
on which some of the new techniques could be proved.
The Cu(II)/Zn reaction has been shown to be diffusion controlled. Five methods, including solution analysis, have been used to determine the rate of reaction. The values of the rate constants thus determined were in good agreement provided allowance was made for the nonstoichiometry of this reaction due to proton displacement by zinc.
The Co(II)/Zn cementation reaction, though thermodynamically highly
favourable, is kinetically very sluggish. Of the factors affecting this reaction, the solution pH was found to play a substantial role. For example, while the reaction is largely under chemical control, at pH 5 the reaction rate becomes limited by the speed at which cobalt(I1) ions diffuse to the reacting metal surface. The favourable influence of a higher pH on the reduction of cobalt(II) carried out either electrochemically or chemically using zinc powder was ascribed to the increasing formation of the electrochemically active species, CoOH+ . Increasing the temperature also favours the shift from chemical control to diffusion control.
Values for the rate constants of the Co(II)/Zn reaction in the absence of added zn2+ ions were determined from Evans' diagram, chronopotentiometry and impedance spectroscopy, The reasons for the differences in the values of rate thus obtained were discussed.
The presence of zinc ions in the reaction solution greatly suppressed the rate of Co(II)/Zn cementation reaction. Several factors have been identified as contributing to the reduced reaction rate. These are the double layer effect, zinc ion and hydrogen atom adsorption, and precipitation of basic zinc salts which blanket the reacting metal surface.
The action of compounds such as Sb(III) and As(III), which are commonly used to activate the Co(II)/Zn reaction in the presence of large amounts of zn2+, was investigated mainly by impedance spectroscopy. From the similarity of the impedance spectra for the reaction i n the presence of
benzoqui none, it was inferred that one role of the activators was to suppress the formation of adsorbed hydrogen on the reacting surface and to allow a higher concentration of the active species, COOH'.
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Elhadayri, Farj Civil & Environmental Engineering Faculty of Engineering UNSW. "Experimental investigation static liquefaction of lightly cemented sands." Awarded by:University of New South Wales. Civil & Environmental Engineering, 2008. http://handle.unsw.edu.au/1959.4/43104.
Full textAbstract:
An experimental investigation was conducted on the static liquefaction behaviour of very loose lightly cemented sands. Undrained and drained triaxial compression tests, one dimensional consolidation, high stress compression, and unconfined compression tests were performed on artificially prepared lightly cemented loose samples with cement-sand ratios of 2, 4 and 6%. Additional tests were also conducted on uncemented samples prepared at the same initial void ratio as the cemented samples. Besides the influence of degree of cementation, the effects of void ratio and confining pressure on the liquefaction potential of cemented sands were examined. The aim of this study is to make significant contribution to the understanding of static liquefaction failures in lightly cemented sands. It is shown that cementation could increase the initial stiffness and yield strength of cemented sands but its effect might decrease considerably after the peak strength because of destruction of the cementation bond. The response of cemented sands at lower cement contents was very similar to the response of loose sands and behaviour approached the response of medium to dense sands with increase in the degree of cementation. It is also shown that degree of cementation has a significant influence on liquefaction resistance. Even though the presence of small amounts of cementation did not prevent liquefaction failure, the liquefaction resistance of cemented sands generally increased for higher degrees of cementation. The consolidation, high stress compression and unconfined compression tests demonstrated the effect of cementation in increasing both the stiffness and strength of cemented sands. The unconfined compression strength increased approximately linearly with the increase in cement content. The rate of strength gain increased with an increase in the dry density of the compacted sample, indicating that the cementation was more for denser samples.
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Wang, Yongqing. "Aluminide coatings on Fe-9Cr-1Mo steel synthesized by pack cementation for power generation applications : a dissertation presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online version, 2006. http://proquest.umi.com/pqdweb?index=89&did=1260818241&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1255459401&clientId=28564.
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Kenyon-Roberts, Stephen M. "The petrography and distribution of some calcite sea hardgrounds." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318580.
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Williams, Randolph T. "A Combined Experimental and Numerical Approach to Understanding Quartz Cementation in Sandstones." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1339354653.
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Harper, Mark Andrew. "Codeposition of chromium and silicon onto iron-base alloys via pack cementation /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487778663285375.
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Lee, Jaeheon. "Gold cementation on copper in thiosulfate solution: Kinetic, electrochemical, and morphological studies." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280482.
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Cyanidation has been used for more than a century for precious metal recovery and it is still in use today. Cyanide is a very toxic chemical and if not used appropriately will cause environmental problems. There is considerable attention devoted to the development of non-cyanide lixiviants for the process of gold and silver ores. Thiosulfate solution is one of the proposed alternatives to cyanide and gold cementation by copper has been suggested as a promising method for gold recovery from leaching solution. Copper powder and rotating disc electrode were used for the kinetic study. The rate of gold cementation on copper disc is proportional to the initial gold concentration and disc rotating speed. The cementation reaction exhibited two distinct kinetic regions, an initial slow rate followed by an enhanced rate. The activation energy of the reaction was 5.9 kJ/mol at low copper concentration and the reaction is mass transport controlled. With 30 ppm initial copper concentration, there was noticeable decrease in the reaction rate in high temperature range. EDS, XRD, and XPS analysis revealed that the deposits are a Au-Cu alloy instead of pure gold. The alloy composition ranged from Au₃Cu to AuCu₃ depending on the initial Cu/Au mole ratio in solution and applied potential. Electrochemical studies were performed using rotating disc electrode and electrochemical quartz crystal nanobalance. Evans' diagrams were constructed under various experimental conditions. Corrosion current increased with increasing gold concentration, disc rotating speed, as well as thiosulfate concentration. These results confirmed those obtained in the kinetic study. Corrosion potential measurements indicated that passivation onset time was changed by gold concentration, copper concentration and disc rotating speed. Gold(I)-thiosulfate reduction was found to occur at approximately -250 mV vs. SHE using EQCN. Copper adions on the gold surface contributed to the underpotential deposition of copper and the underpotential deposition is the mechanism of alloy formation in cementation system. (Abstract shortened by UMI.)
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Jackson, John Anthony. "Carbonate cementation in sandstones of the Plover Formation, North West Shelf, W.A." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/60110/1/John_Jackson_Thesis.pdf.
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Ancient sandstones include important reservoirs for hydrocarbons (oil and gas), but, in many cases, their ability to serve as reservoirs is heavily constrained by the effects of carbonate cements on porosity and permeability. This study investigated the controls on distribution and abundance of carbonate cements within the Jurassic Plover Formation, Browse Basin, North West Shelf, Australia. Samples were analysed petrographically with point counting of 59 thin sections and mineralogically with x-ray diffraction from two wells within the Torosa Gas Field. Selected samples were also analysed for stable isotopes of O and C. Sandstones are classified into eleven groups. Most abundant are quartzarenites and then calcareous quartzarenites. Lithology ranged between sandstones consisting of mostly quartz with scant or no carbonate in the form of cement or allochems, to sandstones with as much as 40% carbonate. The major sources of carbonate cement in Torosa 1 and Torosa 4 sandstones were found to be early, shallow marine diagenetic processes (including cementation), followed by calcite cementation and recrystallisation of cements and allochems during redistribution by meteoric waters. Blocky and sparry calcite cements, indicative of meteoric environments on the basis of stable isotope values and palaeotemperature assessment, overprinted the initial shallow marine cement phase in all cases and meteoric cements are dominant. Torosa 4 was influenced more by marine settings than Torosa 1, and thus has the greater potential for calcite cement. The relatively low compaction of calcite-cemented sandstones and the stable isotope data suggest deep burial cementation was not a major factor. Insufficient volcanic rock fragments or authigenic clay content infers alteration of feldspars was not a major source of calcite. Very little feldspar is present, altered or otherwise. Hence, increased alkalinity from feldspar dissolution is not a contributing factor in cement formation. Increased alkalinity from bacterial sulphate reduction in organic–rich fine sediments may have driven limited cementation in some samples. The main definable and significant source of diagenetic marine calcite cement originated from original marine cements and the nearby dissolution of biogenic sources (allochems) at relatively shallow depths. Later diagenetic fluids emplaced minor dolomite, but this cement did not greatly affect the reservoir quality in the samples studied.
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Kayin, Pinar Burcu. "Removal Of Cobalt From Zinc Sulfate Solution By Cementation Prior To Zinc Electrowinning." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1096759/index.pdf.
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The aim of this study was to investigate the removal of cobalt from zinc sulfate solution by cementation with the help of conventional and new type of additives that were 4% Sn-zinc alloy powder and 10% Sn-zinc alloy powder, respectively. Synthetic leach solutions containing 150 g/l Zn and 75 mg/l Co were prepared and used in all of the experiments. The parameters researched with the conventional method were the amount of arsenic trioxide and the effect of copper sulfate on cementation of cobalt. While using the alloys, the parameters studied were the amounts of arsenic trioxide, copper sulfate and tin containing zinc alloy powder additions, cementation duration and temperature. The difference in the optimization of alloy additions was in the amount of addition of arsenic trioxide. The amount of 4%Sn-zinc alloy powder was tried to be optimized with the addition of arsenic trioxide whereas the optimization was tried to be done without any arsenic addition while using 10%Sn-zinc alloy. The XRD and SEM studies of the cementates were also performed.
The obtained results indicated that tin containing alloys were much better than pure zinc. With the additions of 4 g/l 4%Sn-Zn alloy dust, 1.2 g/l CuSO4.5H2O, 0.12 g/l As2O3 and in 2 hours of cementation duration at 85-90oC, the maximum amount of cobalt cementation efficiency was achieved. The experiments indicated that cobalt in the solution could be reduced to about 2 mg/l by using 10%Sn-zinc alloy powder with an initial Sn/Co weight ratio of 13.25:1 without the addition of arsenic trioxide at 85oC in 2 hours of cementation duration.
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Dale, Annabel Rebecca. "Carbonate clumped isotopes : a new tool to assess carbonate cementation in clastic sediments." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/39782.
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Carbonate cements in clastic rocks capture a geochemical record of burial processes. As such, much of our understanding of clastic diagenesis and subsurface microbial activity is influenced by studies of carbonate cemented horizons and concretions. Furthermore, their presence can have a significant impact on clastic reservoir quality. However, the formation of cement bodies is poorly understood. A part of this problem is that studies investigating carbonate cements have historically been limited by the δ18Ocarbonate being dependent on both the carbonate precipitation temperature and δ18Oporewater. Often, these variables cannot be constrained and one or the other has to be assumed to derive an interpretation, with significant implications for understanding the fluid history and timing or diagenetic processes. This PhD study applies a new geochemical palaeothermometry technique, "carbonate clumped isotopes", to constrain the temperature of the cement precipitation. With this, the δ18Oporewater can be back-calculated and the formation burial history of changes in δ13C and δ18Oporewater can be constrained. This thesis contains three studies using the clumped isotope technique to investigate carbonate cementation. The first examines outcrop carbonate cements in the Mancos Shale, Colorado, where changes in δ13C and δ18Oporewater are captured over a temperature range of 33-117 °C and placed into a burial history. The second study then examines a variety of cements and concretions from different formations around the world to determine the geochemical conditions necessary for cement precipitation, through trends in δ13C, δ18Oporewater and temperature. This reveals that the temperatures of cementation appears to be strongly controlled by the optimal temperature of activity for subsurface microbes. The final study then applies the technique to subsurface carbonate cements in cores from the Bruce Field, UK North Sea. This places carbonate cementation and the δ18Oporewater into the burial history of one of the reservoir formations. The results of this PhD demonstrate the usefulness of carbonate clumped isotopes for understanding clastic carbonate cementation burial histories, in outcrop and the subsurface. Furthermore, they provide an insight into the temperatures at which microbial processes occur during diagenesis and more generally, the chemical conditions common to carbonate cementation.
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Bukar, Mohammed. "Does oil emplacement stop diagenesis and quartz cementation in deeply buried sandstone reservoirs." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/10253/.
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Reservoir quality relates to the presence of porosity and the connectivity of the pores of the reservoir rock which controls permeability. Deeply buried sandstones in sedimentary basins lose their reservoir quality due to compaction and cementation. Quartz cement is the most volumetrically important porosity occluding cement in sandstones buried to depths greater than about 3000m. Precipitation of quartz cement requires a source of silica, transportation of the silica in solution from source to the point of precipitation and clean grain surfaces to grow on. For these processes to take place water is required to dissolve the mineral grains that provide the source of silica, to provide aqueous fluid pathway from the site of mineral dissolution to the site of precipitation and water is required at the site of mineral precipitation to enable mineral growth. In oil or gas fields, displacing the aqueous pore fluid by petroleum disrupts the pathway between the reactants and points of precipitation. If the oil saturation becomes high; (i) the residual (irreducible) water becomes isolated within a continuous hydrocarbon phase or (ii) the aqueous pathway becomes tortuous and diffusion becomes slow or (iii) grain surfaces become coated by oil if the sandstone is oil wet. However, over the years a controversy has developed as to whether oil emplacement into reservoir stops quartz cementation and preserves porosity at depth. The research presented in this thesis used core samples, wireline logs and well reports collected from the oil and water legs and the transition zone of Upper Jurassic marine sandstones of the Ula and Tambar fields from the Norwegian North Sea. They were studied using a range of techniques: core analysis, core logging, downhole wireline analysis, optical microscopy, scanning electron microscope (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), fluid inclusion UV-petrology and thermometry. The distributions of all potential controls on porosity and permeability have been quantified so that it has been possible to assess the influence of all possible controls on quartz cement as well as fluid type. Thus the roles of depositional facies, grain size, sorting, chlorite coats and microcrystalline quartz coats have all been assessed. The main diagenetic cements in both Ula and Tambar fields are quartz overgrowths, grain coating microcrystalline quartz, K-feldspar cement, illite, dolomite and minor amounts of calcite and chlorite. Fluid inclusion evidence shows that quartz cementation was probably a continuous process and is still taking place in both fields. Quartz cementation occurred in the presence of some oil, as shown by the presence of oil inclusions within quartz cement in both Ula and Tambar. However, there are far fewer oil inclusions in quartz cement in Tambar than Ula suggesting that oil emplacement occurred later in Tambar than Ula. There is less quartz cement in the coarser grained sandstones in the oil legs than the water legs of Ula and Tambar suggesting that quartz cementation has been inhibited, in these facies, by the addition of oil. Finer-grained facies in both fields have more grain-coating microcrystalline quartz that has effectively inhibited quartz cementation in both oil and water legs. Stable isotope data show that the carbonate cements in the oil leg grew at relatively lower temperatures than those in the water legs. Precipitation temperature for carbonate cement in the oil leg stopped at the time of oil emplacement but carbonate cements in the water leg carried on growing or recrystallising at higher temperatures and show progressive input of source-rock derived CO2 (as the carbon isotopes get progressively lighter) in both Ula and Tambar fields. Reservoir quality in the Ula field is primarily controlled by a combination of depositional facies, mechanical compaction and early oil emplacement and locally by facies-controlled microcrystalline quartz. In the Tambar field early-formed grain-coating microcrystalline quartz mainly controls the reservoir quality and effects of oil emplacement are not as significant as in Ula due to the later oil charge. The results of this work have academic and economic significance. Understanding the controls on reservoir quality and the effect of oil emplacement on quartz cementation may be used (1) as analogues in other basins of known petroleum charge history, (2) to improve appropriate reserve calculation and well planning during the appraisal stage and (3) to assist in reliable prediction of aquifer performance during production, and lead to proper decision on number and positions of injection wells during the later life of the field.
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Polo, Montes Carlos A. "The effect of cementation technique on the retention of adhesively cemented prefabricated posts." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/polomontes.pdf.
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Jennings, Jonathan Simon. "Fracture kinematics, cementation and burial history of a structurally polyphase sedimentary basin, Tunisia." Thesis, Kingston University, 2001. http://eprints.kingston.ac.uk/20680/.
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Basin analysis of over 1000km of 2-D seismic profiles and thirteen exploration wells from the North and South Kairouan Permits in the foreland region of the Tunisian Atlas has led to the identification of a number of late Mesozoic to recent basin systems. The generation of these basin systems resulted in the development of fractures and emplacement of diagenetic fluids and hydrocarbons in the early Campanian to early Maastrichtian (83.5-70Ma) chalks of the Abiod Formation. Recognition of the basin-forming events has been based on the identification of regional unconformities, subsurface thickness variations of mid-Cretaceous to recent strata, and changes in the location and size of depocentres. The basin systems correspond to: (1) early Albian to early Campanian (110-83.5Ma) extension related to convergence across Tethys during the opening of the North Atlantic; (2) early Campanian to late Langhian (83.5-l5Ma) basin inversion and salt diapirism related to the convergence between Africa and Europe; (3) late Langhian to late Tortonian (15-7Ma) basin inversion, salt diapirism and foreland basin sedimentation associated with the southeastwards propagation of the Atlas Mountains thrust-system through the Mejerda Zone, Intermediate Atlas and into the North-South Axis; (4) late Tortonian to Late Pliocene (7-1.8Ma) extension related to the opening of the Strait of Sicily and foreland basin sedimentation from the North-South Axis; (5) Late Pliocene to recent (1.8- 0Ma) basin inversion related to the final stages of deformation along the North-South Axis. Hydrocarbons in the North and South Kairouan Permits are produced from open and partially open fractures in the upper Abiod Formation. Petrographic analysis has allowed the identification of ferroan calcite, ferroan dolomite and barite cements in fractures of the upper Abiod Formation which were emplaced in that order. The integration of burial history modelling and fluid inclusion analysis suggests that the pressure-corrected homogenisation temperatures (trapping temperatures) for the ferroan calcites are 59-660°C and for the ferroan dolomites are 78-93°C. Even though the polyphase fracturing events range from the late Mesozoic to recent, the integration of burial history modelling, petrographic, Formation MicroScanner/MicroImager and fluid inclusion analysis have constrained the timing of reservoir charging by diagenetic fluids to the: (1) late Langhian (15Ma) for the ferroan calcite cements; (2) Late Pliocene to recent (l.8-0Ma) for the ferroan dolomite and barite cements. Stable carbon and oxygen isotope analysis on samples of the fracture fills, in conjunction with fluid inclusion trapping temperatures, suggests that the [delta][sup]180 and [delta][sup]13C ratios of the fluids responsible for the recipitation of calcite cements ([delta][sup]18O[sub]H2O = +3.70% to +3.80% V-SMOW, [delta][sup]13C[sub]HCO3 = +0.02% to +0.08% V-PBD) were connate waters derived from marine carbonates. Dolomite cements ([delta][sup]18O[sub]H2O = -3.00% to +0.30% V-SMOW, [delta][sup]13C[sub]HCO3 = -2.53% to -1.16% V-PDB) were precipitated from meteoric waters with an input of soil-derived organic carbon. The meteoric waters were probably derived from an area of recharge that was located to the northwest of the study area towards the thrust-front of the Atlas Mountains, during the development of the North-South Axis. Burial history modelling indicates that hydrocarbons would have reached mid-maturity in source rocks beneath the Abiod Formation (Mouelha Member, 110-99Ma; Bahloul Horizon, 95-93.5Ma), from the Late Pliocene onwards (<1.8Ma). Petroleum was probably transported into the fractured upper Abiod Formation coeval with the fluids responsible for the precipitation of the ferroan dolomite cements and/or for the precipitation of the barite cements during the final stages of basin inversion (1.8-0Ma).
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Adams, Andrew. "An assessment of the effects of pozzolanic activity on the behaviour of fly ash." Thesis, Durham University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342795.
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Villias, Aristeidis [Verfasser]. "Effects of cementation on exposed luting agent profile at implant-supported crowns / Aristeidis Villias." Köln : Deutsche Zentralbibliothek für Medizin, 2016. http://d-nb.info/1081824557/34.
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Ravi, Vilupanur Alwar. "Simultaneous chromizing-aluminizing of nickel and nickel base alloys by halide activated pack cementation /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487597424136616.
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Achuthankutty, Ajith. "Deposition Kinetics of Titanium and Zirconium Diffusion Coatings on Nickel Microwires via Pack Cementation." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133155467387.
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Al, Harthi Amena Dhawi Juma Mayoof. "Dynamics of calcite cementation in response to oil charge and reservoir evolution, Thamama, Group, U.A.E." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33102.
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Carbonate rocks consider as significant reservoirs for hydrocarbon. More than 60% of the world's hydrocarbon is placed in carbonate reservoirs. Carbonate rocks are heterogeneous and contain complex pore system. This complexity causes the hydrocarbon recovery from these reservoirs difficult; having less than 35% of hydrocarbon is being recovered. The heterogeneity and the variation in pore system are a result of various depositional settings and successive diagenetic overprints. Diagenetic overprints account for most of the pore system complexity in subsurface. This project undertakes one of the important diagenetic processes, calcite cementation, which though to have major impact on reservoir quality. The project aims to better understand the controls on calcite cementation in five Lower Cretaceous Reservoirs, in particular the role of calcite cementation with relation to oil charge in reservoir quality. Other diagenetic processes were also asses including dolomitization, dissolution, micritization and chemical compaction. The five reservoirs (A, B, C, F & G) are from Field A which is located in Abu Dhabi, UAE. The reservoirs comprise of interbedded porous "Reservoir" and low porosity-permeability "Dense" limestones deposited in broad range of settings, ranging from restricted to open marine platform. Reservoir intervals are part of HSTs, deposited during higher sea level time. The dense intervals were deposited during TST and thought to be cemented early resulting in early compartmentalization in all reservoirs. The mMg/Ca and in-situ (SIMS) δ18OVPDB were measured through complete calcite cement stratigraphy obtained from equant, syntaxial and blocky calcite in all reservoirs. Both mMg/Ca and δ18OVPDB of oldest calcite cement zone are matching with published mMg/Ca and δ18OVPDB of Lower Cretaceous, suggesting precipitation from Lower Cretaceous seawater. The mMg/Ca and δ18OVPDB also vary from reservoir to another reflecting change in Cretaceous seawater. These data also coincide with trace element observations particularly Mn and Sr. All these parameters show fluctuations in Cretaceous seawater during 135-123Ma caused by global changes in climate and oceanic crust production rates. Lower reservoirs including F (133Ma) and C (130Ma) were more probably affected by the Hauterivian global cooling which resulted in higher δ18OVPDB in the early precipitated cements. Precipitation in upper Reservoir B (126Ma) was most likely affected by the abrupt warm episode just before the OAE1. Reservoir A (123Ma) precipitation may be affected by the Early Aptian cooling episode and the OAE1. Reservoir G is the only one not recording δ18OVPDB similar of Cretaceous seawater. Cementation in Reservoir G was affected by depleted δ18OVPDB fluids from early stage, perhaps hot, basinal waters. More interestingly, the mMg/Ca, δ18OVPDB Mn and Sr means of younger calcite cement zones which thought to be evolved during burial show similar trend to the oldest cement zones with various offsets. This suggests that calcite cement in each reservoir evolved in a relatively close system inferring by this that the reservoirs are compartmentalized. The compartmentalization is probably due to the sysedimentary or early cemented hardgrounds in the Dense Zones. The Dense Zones acted as seals for the reservoirs from early stage causing the later precipitated calcite cement which is diagenetically affected to behave in predictable and similar way. Moreover, calcite precipitation temperatures inferred from mMg/Ca and δ18OVPDB show progressive increase towards younger cement zones indicating fluid evolution with burial in also relatively close system. In-situ δ18OVPDB and oil inclusions suggest earlier oil charge in the shallower reservoirs compared with deeper reservoirs and coeval water leg. Consequently, cementation in the shallower reservoirs continued with lower rate and hence preserved some primary and secondary pores. Conversely, in the water leg cementation continue to occlude most of the pore spaces. Furthermore, early oil emplacement in the shallower reservoirs increased the cementation temperature of calcite in the oil leg to reach maximum precipitation temperatures of ~144˚C. Whereas, in the water leg and deeper reservoirs, cementation continued to a temperature of ~110˚C. Overall, reservoir quality in Thamama Group was affected by various diagenetic processes. Some have resulted in reservoir quality enhancement such as dolimitization which involves formation of microporosity as a result of replacive rhombic dolomite, dissolution particularly the late one which believed to be due organic acid, and micritization with yield microporosity particularly in Reservoir B. Open fractures might have also enhanced reservoir quality to some extent. Diagenetic events that have deteriorated reservoir quality include calcite and saddle dolomite cementation as well as stylolitization. Greater calcite cementation can be found in water leg compared with oil leg because oil thought to decrease cementation rate.
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MAKLOUFI, LAID. "Cementation electrochimique de l'argent par le plomb en solution aqueuse concentree de chlorure de sodium." Grenoble INPG, 1987. http://www.theses.fr/1987INPG0069.
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Alainachi, Imad Hazim. "Shaking Table Testing of Cyclic Behaviour of Fine-Grained Soils Undergoing Cementation: Cemented Paste Backfill." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41524.
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Cemented paste backfill (CPB) is a novel technology developed in the past few decades to better manage mining wastes (such as tailings) in environmentally friendly way. It has received prominent interest in the mining industry around the world. In this technology, up to 60% of the total amount of tailings is reused and converted into cemented construction material that can be used for secondary support in underground mine openings (stopes) and to maximize the recovery of ore from pillars. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement), that is mixed in the paste plant and delivered into the mine stopes either by gravity or pumping. During and after placing it into the mine stopes, the performance of CPB mainly depends on the role of the hydraulic binder, which increases the mechanical strength of the mixture through the process of cement hydration. Similar to other fine-grained soils undergoing cementations, CPB’s behavior is affected by several conditions or factors, such as cement hydration progress (curing time), chemistry of pore water, mixing and curing temperature, and filling strategy. Also, it has been found that fresh CPB placed in the mine stopes can be susceptible to many geotechnical issues, such as liquefaction under ground shaking conditions. Liquefaction-induced failure of CPB structure may cause injuries and fatalities, as well as significant environmental and economic damages. Many researches studied the effect of the aforementioned conditions on the static mechanical behavior of CPB. Other researches have evaluated the liquefaction behavior of natural soils and tailings (without cement) during cyclic loadings using shaking table test technique. Only few studies investigated the CPB liquefaction during dynamic loading events using the triaxial tests. Yet, there are currently no studies that addressed the liquefaction behavior of CPB under the previous conditions by using the shaking table technique. In this Ph.D. study, a series of shaking table tests were conducted on fresh CPB samples (75 cm × 75 cm ×70 cm), which were mixed and poured into a flexible laminar shear box (that was designed and build for the purpose of this research). Some of these shaking table tests were performed at different maturity ages of 2.5 hrs, 4.0 hrs, and 10.0 hrs, to investigate the effect of cement hydration progress on the liquefaction potential of CPB. Another set of tests were conducted to assess the effect of the chemistry (sulphate content) of the pore-water on the cyclic response of fresh CPB by exposing cyclic loads on couple of CPB models that contain different concertation of sulphate ions of 0.0 ppm and 5000 ppm. Moreover, as part of this study, series of shaking table test was conducted on CPB samples that were prepared and cured at different temperatures of 20oC and 35oC, to evaluate the effect of temperature of the cyclic behavior of CPB. Furthermore, the effect of filling strategy on the cyclic behavior of fresh CPB was assessed by conducting set of shaking tables tests on CPB models that were prepared at different filling strategies of continuous filling, and sequential or discontinuous (layered) filling. The results obtained show that CPB has different cyclic behavior and performance under these different conditions. It is observed that the progress of cement hydration (longer curing time) enhances the liquefaction resistance of CPB, while the presence of sulphate ions diminishes it. It is also found that CPB mixed and cured in low temperature is more prone to liquefaction than those prepared at higher temperatures. Moreover, the obtained results show that adopting the discontinuous (layered) filling strategy will improve the liquefaction resistance of CPB. The finding presented in this thesis will contribute to efficient, cost effective and safer design of CPB structures in the mine areas, and will help in minimizing the risks of liquefaction-induced failure of CPB structures.
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Nchabeleng, Ramphagane Frank. "Gold recovery from waste mobile phones PCBs using ammonia thiosulphate leaching and copper cementation process." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2855.
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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018.The rate of waste electrical and electronic equipment (WEEE) is growing at an alarming rate, especially in countries where markets are saturated with huge quantities of new electronic goods. Printed circuit boards (PCBs) are a substantial portion of the value contained in waste from WEEE although they are only 6% of the total weight. It is reported that WEEE is currently the fastest growing waste stream in South Africa as the general population’s access to electronic goods in the last decade has increased, especially access to mobile phones. PCBs are found in any piece of electrical or electronic equipment and consist of various metals including precious metals such as gold (Au), silver (Ag) and palladium (Pd). It is reported that gold has the highest economic incentive at 15,200 $ per ton of PCBs. The rapid introduction of new and advanced technology into mobile phones has caused mobile phones to have a relatively short life span, 1 to 2 years to be exact. Mobile phones printed circuit boards (MPPCBs) have more Au content compared to computer circuit boards. They contain 350 g/ton Au whereas computer (PC) PCBs contains 250 g/ton. This research project will recover gold from waste mobile phones PCBs pregnant ammonia thiosulphate leach solution using copper cementation. The cementation process is preferred to all the other technologies of metals extraction from solution due to ultrahigh purity metals that can be obtained and to the less consumption of materials and energy. Electronic parts on the PCBs were manually removed using pliers and screwdrivers. PCBs were then cut to smaller pieces of about 2 x 2 m. The pieces were crushed and milled respectively. Some of the particles were recycled back to the crusher to get finer particles. The particles were separated to particles of sizes between 0 and 1350 μm using a shaker. The comminuted fractions of the PCBs were then used in the leaching step. Batch cementation experiments were performed by bubbling N2 in glass reaction vessel with a working volume of 0.5 L. The reactor was connected to a circulating water bath for temperature control. The recovery percentage of gold at various temperatures, agitation speeds and different amounts of copper powder used, was determined while pH was monitored. The temperature was varied at 30 °C, 40 °C, and 50 °C and the agitation speeds at 300 RPM and 900 RPM. Copper powder was added at 0.5 g/L, 1 g/L, and 1.5 g/L. Gold concentrations were measured by atomic adsorption spectrophotometer (AAS). Scanning electron microscope (SEM) and Energy-dispersive x-ray spectrometry (EDS) analyses of the copper powder after cementation (precipitates) were used to determine the surface morphology and to evaluate the quantitative aspect of the precipitate. It was found that the recovery of gold from ammonia thiosulphate leach solution was greatly affected by agitation speed. At an agitation speed of 900 rpm, 40 °C and 0.5 g of Copper powder, 96% of the gold was recovered from the leach solution. The cementation rate increased as temperature was elevated from 30 to 40 °C, but slightly decreased as the temperature reached 50 °C. The change in experimental conditions affected the gold concentration on the precipitate recovered. This study will provide a possible solution to the WEEE problem and more specifically mobile cell phones, in South Africa.
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Nejedlik, John. "Petrographic image analysis as a tool to quantify porosity and cement distribution." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09SM/09smn417.pdf.
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Includes bibliographical references (leaves 153-157). Petrographic image analysis proved particularly useful in determining the parameters for statistical analysis for the simple mineralogies displayed in the samples from the Hutton Sandstone. Concentrates on establishing techniques for statistical study of data collected by PIA to subdivide the framework grains from the porosity or cement.
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Hipólito, Ana Carolina [UNESP]. "Efeito da limpeza pós-condicionamento e do tratamento térmico do silano na resistência de união de um cimento resinoso à cerâmica." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/123678.
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000831389.pdf: 2171410 bytes, checksum: 8516ec39315e5fd0cac80b4a540a7e3d (MD5)Proposição: O objetivo do estudo foi avaliar o efeito da limpeza com ácido fosfórico após condicionamento da cerâmica e do tratamento térmico do silano na resistência de união de um cimento resinoso à cerâmica de dissilicato de lítio submetido ao envelhecimento. Método: Foram confeccionados sessenta e quatro blocos de cerâmica de dissilicato de lítio (IPS e-‐max CAD, Ivoclar Vivadent) e de resina composta (7x8x4mm). Os corpos de prova foram divididos aleatoriamente em 4 grupos (n=16) que receberam os seguintes tratamentos: HFS (grupo controle): ácido fluorídrico 10 % e silano; HFPS: ácido fluorídrico, ácido fosfórico 37% e silano; HFSa: ácido fluorídrico e silano aquecido (45◦C ± 5◦C); HFPSa: ácido fluorídrico, ácido fosfórico e silano aquecido. Os espécimes foram cimentados com um cimento resinoso dual, posteriormente os corpos de prova foram divididos em duas condições de envelhecimento (n=8): N - sem envelhecimento e TC: termociclagem 12.000X, 5◦C - 55 ◦C. Foram submetidos ao teste de microtração em uma máquina de testes com velocidade de 0,7mm/min. As superfícies fraturadas foram examinadas para determinar o modo de falha. Os dados estatísticos foram analisados através da Anova de 2 fatores e as médias comparadas por meio do teste Tukey (p< 0.05). Resultados: o grupo HFSa envelhecido apresentou o maior valor de resistência de união (21,49 ± 2,29 MPa), entretanto, sem diferença estatística para o grupo controle (p<0,05). Não houve diferença estatisticamente significante entre as amostras envelhecidas e não envelhecidas, entretanto, foi observada uma diferença estatisticamente significante no grupo HFSa. (p<0,05). Importância: O tratamento térmico do silano e a limpeza pós-‐condicionamento com ácido fosfórico não potencializou a resistência de união da cerâmica à resina
Purpose: The aim of this study was to evaluate the effect of cleaning with phosphoric acid after etching of ceramic and heat treatment of the silane with a stream of hot air on the bond strength of a resin cemente to lithium dissiliacte ceramic submitted to aging. Method: Sixty-‐four blocks-‐ceramic lithium silicate (IPS e-‐max CAD, Ivoclar Vivadent) and composite resin were fabricated (7x8x4mm). The specimens were randomly divided into 4 groups (n = 16) that received the following treatments: HFS (control group): 10% hydrofluoric acid and silane; HFPS: hydrofluoric acid, 37% phosphoric acid and silane; HFSA: hydrofluoric acid and silane heated (45 ◦ C ± 5 ◦ C); HFPSa: hydrofluoric acid, phosphoric acid and heated silane. The specimens were cemented with a dual resin cement, later the specimens were divided into two aging conditions (n = 8): N -‐ no aging and TC: thermocycling, 12,000 x 5◦C -‐ 55◦C. They were submitted to microtensile test in a testing machine with a speed of 0.7 mm / min. Fractured surfaces were examined to determine the failure mode. Statistical data were analyzed by ANOVA with 2 factors and the averages compared by Tukey test (p <0,05). Results: The group HFSa aged showed the highest bond strength (21.49 ± 2.29 MPa), however, without statistical difference for the control group. There was no statistically significant difference between aged and non-‐aged samples, except for, a statistically significant difference in the HFSA group (p <0.05). Significance: The heat treatment of the silane and cleaning after etching with phosphoric acid did not increase the bond strength of ceramic resin
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Hipólito, Ana Carolina. "Efeito da limpeza pós-condicionamento e do tratamento térmico do silano na resistência de união de um cimento resinoso à cerâmica /." Araçatuba, 2014. http://hdl.handle.net/11449/123678.
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Orientador: Wirley Gonçalves AssunçãoBanca: Paulo Henrique dos Santos
Banca: Linda Wang
Resumo: Proposição: O objetivo do estudo foi avaliar o efeito da limpeza com ácido fosfórico após condicionamento da cerâmica e do tratamento térmico do silano na resistência de união de um cimento resinoso à cerâmica de dissilicato de lítio submetido ao envelhecimento. Método: Foram confeccionados sessenta e quatro blocos de cerâmica de dissilicato de lítio (IPS e-‐max CAD, Ivoclar Vivadent) e de resina composta (7x8x4mm). Os corpos de prova foram divididos aleatoriamente em 4 grupos (n=16) que receberam os seguintes tratamentos: HFS (grupo controle): ácido fluorídrico 10 % e silano; HFPS: ácido fluorídrico, ácido fosfórico 37% e silano; HFSa: ácido fluorídrico e silano aquecido (45◦C ± 5◦C); HFPSa: ácido fluorídrico, ácido fosfórico e silano aquecido. Os espécimes foram cimentados com um cimento resinoso dual, posteriormente os corpos de prova foram divididos em duas condições de envelhecimento (n=8): N - sem envelhecimento e TC: termociclagem 12.000X, 5◦C - 55 ◦C. Foram submetidos ao teste de microtração em uma máquina de testes com velocidade de 0,7mm/min. As superfícies fraturadas foram examinadas para determinar o modo de falha. Os dados estatísticos foram analisados através da Anova de 2 fatores e as médias comparadas por meio do teste Tukey (p< 0.05). Resultados: o grupo HFSa envelhecido apresentou o maior valor de resistência de união (21,49 ± 2,29 MPa), entretanto, sem diferença estatística para o grupo controle (p<0,05). Não houve diferença estatisticamente significante entre as amostras envelhecidas e não envelhecidas, entretanto, foi observada uma diferença estatisticamente significante no grupo HFSa. (p<0,05). Importância: O tratamento térmico do silano e a limpeza pós-‐condicionamento com ácido fosfórico não potencializou a resistência de união da cerâmica à resina
Abstract: Purpose: The aim of this study was to evaluate the effect of cleaning with phosphoric acid after etching of ceramic and heat treatment of the silane with a stream of hot air on the bond strength of a resin cemente to lithium dissiliacte ceramic submitted to aging. Method: Sixty-‐four blocks-‐ceramic lithium silicate (IPS e-‐max CAD, Ivoclar Vivadent) and composite resin were fabricated (7x8x4mm). The specimens were randomly divided into 4 groups (n = 16) that received the following treatments: HFS (control group): 10% hydrofluoric acid and silane; HFPS: hydrofluoric acid, 37% phosphoric acid and silane; HFSA: hydrofluoric acid and silane heated (45 ◦ C ± 5 ◦ C); HFPSa: hydrofluoric acid, phosphoric acid and heated silane. The specimens were cemented with a dual resin cement, later the specimens were divided into two aging conditions (n = 8): N -‐ no aging and TC: thermocycling, 12,000 x 5◦C -‐ 55◦C. They were submitted to microtensile test in a testing machine with a speed of 0.7 mm / min. Fractured surfaces were examined to determine the failure mode. Statistical data were analyzed by ANOVA with 2 factors and the averages compared by Tukey test (p <0,05). Results: The group HFSa aged showed the highest bond strength (21.49 ± 2.29 MPa), however, without statistical difference for the control group. There was no statistically significant difference between aged and non-‐aged samples, except for, a statistically significant difference in the HFSA group (p <0.05). Significance: The heat treatment of the silane and cleaning after etching with phosphoric acid did not increase the bond strength of ceramic resin
Mestre
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Hernandes, da Fonseca Natália Maria Aparecida 1986. "Influência do pré-aquecimento na resistência de união de agentes cimentantes utilizados para a fixação de pinos de fibra de vidro = Influence of pre-heating on the bond strength of fiber posts cemented with different lutting agents." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288864.
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Orientador: Flávio Henrique Baggio AguiarTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo in vitro avaliou a influência do pré-aquecimento na resistência de união de três agentes utilizados para a cimentação de pinos de fibra de vidro Reforpost nº 2. Para tal propósito, foram utilizadas 42 raízes de pré-molares humanos previamente extraídos e com tratamento endodôntico realizado e foram divididos, aleatoriamente, em 6 grupos (n=7) de acordo com o agente de fixação (um cimento resinoso dual Rely X ARC; um cimento autoadesivo Rely X U200; e uma resina composta de baixa viscosidade SureFil SDR flow) e temperatura de pré-aquecimento (23ºC; 54ºC). Todos os agentes de cimentação foram fotoativados através de uma fonte de luz LED com irradiância de 1100 mW/cm² durante 40 segundos. As raízes foram armazenadas em água destilada à 37ºC por sete dias e foram cortadas em fatias com espessura de 1,0 mm cada, os quais foram divididos de acordo com o terço do canal radicular (cervical; médio; apical). Em seguida, as amostras foram submetidas ao teste de resistência ao cisalhamento por extrusão para a mensuração em cada terço do canal radicular. Os dados foram submetidos à ANOVA 3 critérios com parcelas subdivididas e teste de Tukey (? = 0,05). Foram encontradas diferenças significativas entre os três cimentos resinosos. (P < 0,0017); no entanto não foram encontradas diferenças entre os grupos não aquecidos e os grupos pré-aquecidos, diferentes regiões da raiz ou para qualquer interação entre os fatores (p > 0,05). Os grupos cimentados com o cimento resinoso Rely X ARC apresentou maiores resultados de resistência de união do que os grupos cimentados com a resina de baixa viscosidade SureFil SDR flow. O cimento autoadesivo Rely X U200 obteve resistência de união intermediária, sem diferença estatística para RelyX ARC ou SureFil SDR flow. Assim, conclui-se que, a utilização de cimento dual convencional pode ser indicada para cimentação de pinos de fibra de vidro e que o pré-aquecimento de cimentos resinosos não é efetivo para o aumento da resistência de união de pinos pré-fabricados
Abstract: This in vitro study investigated the influence of pre-heating on the bond strength of three agents used for cementing fiber posts Reforpost # 2. For that, forty-two human premolars roots with endodontic treatment performed were randomly divided into 6 groups (n = 7), according with the luting agent (a dual resin cement Rely X ARC; a self-adhesive cement Rely X U200; and a flowable composite SureFil SDR flow) and the pre-heating temperature (23° C; 54° C). All luting agents were light-cured with a LED unit ¿ 1,100 mW/cm² for 40 seconds. The roots were stored in distilled water at 37° C for seven days and after that, the roots were cut into slices of 1.0 mm thickness each, which were divided according to the third of the root canal (cervical; middle; apical). Then the specimens were submitted to push out test to measure the bond strength in each third of the root canal. Data were submitted to three-way split-spot ANOVA and Tukey's test (? = 0.05). Significant differences were found among the three luting agent studied (p < 0.0017); however, no difference was found among the pre-heating temperature, root segments or for any interaction between the factors (p > 0.05). Groups luted with resin cement Rely X ARC showed significant higher retentive strength than flowabe composite SureFil SDR flow. Rely X U200 showed intermediary retentive strength means, without statistical difference for Rely X ARC or SureFil SDR flow. Thus, it is concluded that the use of conventional dual cement should be indicated to luting fiber posts and the resin cement pre-heating is not effective to increase the retentive strength of fiber post
Doutorado
Dentística
Doutora em Clínica Odontológica
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Priest, Matthew. "Synthesis of reactive element-modified aluminide coatings on single-crystal Ni-based superalloys by a pack cementation process a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=26&did=1760523421&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1254926883&clientId=28564.
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Anderson, Alan. "A geoseismic investigation of carbonate cementation of the Namur Sandstone in the Gidgealpa Field, Eromanga Basin /." Title page, contents and abstract only, 1985. http://web4.library.adelaide.edu.au/theses/09S.B/09s.ba545.pdf.
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