Dissertations / Theses on the topic 'Cobalt'
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England, Craig Dennis. "Properties of cobalt/copper and cobalt/palladium multilayers." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185707.
Full textReinikainen, Matti. "Cobalt and ruthenium-cobalt catalysts in CO hydrogeneration and hydroformylation /." Espoo : Technical Research Centre of Finland, 1998. http://www.vtt.fi/inf/pdf/publications/1998/P363.pdf.
Full textPigram, David Dennis. "The electronic structure of the ferromagnets cobalt and cobalt disulphide." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306516.
Full textBallou, Rafik. "Anisotropies magnétiques du cobalt dans les composés intermétalliques lanthanide-cobalt." Grenoble 1, 1987. http://www.theses.fr/1987GRE10114.
Full textBallou, Rafik. "Anisotropies magnétiques du cobalt dans les composés intermétalliques lanthanide-cobalt." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602561f.
Full textPour, Asghar Tajali. "Electrocrystallisation of cobalt." Thesis, Coventry University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279419.
Full textGrant, Simon Jonathon. "Azamacrocyclic cobalt catalysts." Thesis, University of Warwick, 1991. http://wrap.warwick.ac.uk/109401/.
Full textSun, Lihui. "Synthesis and reactivity of some cobalt-, phosphorus-chiral cobalt(III) complexes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34235.pdf.
Full textZitoun, David. "Synthèse et magnétisme de nanoparticules de cobalt/rhodium et cobalt/ruthénium." Toulouse 3, 2003. http://www.theses.fr/2003TOU30078.
Full textUllman, Andrew. "Polynuclear Cobalt Complexes as Models of a Cobalt Water Oxidation Catalyst." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845429.
Full textChemistry and Chemical Biology
Felippini, Ana Luiza de Carvalho. "Estudo de metais pesados comumente utilizados na reabilitação oral: efeitos do cobalto no epitélio adamantino, epitélio juncional, gengiva inserida e ligamento periodontal." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/58/58131/tde-13112007-084209/.
Full textCobalt is one of the main components of cast metal alloys broadly used in dentistry. It is the constituent of 45 to 70% of numerous prosthetic works. There is evidence that metal elements cause systemic and local toxicity. The purpose of the present study is to evaluate cobalt effects on the junctional epithelium, adamantine epithelium, inserted gum epithelium, and periodontal ligament of the superior first molar in rats, during lactation. To do this, 1-day old rats were used, whose mothers received 300mg of cobalt chloride per liter of distilled in the drinker (treated group T) and rats whose mothers did not receive CoCl2 (control group C), during lactation. After 21 days, the rat pups were killed with an anesthetic overdose. The heads were separated and fixed in an alfac solution (80% alcohol-85ml, formaline-10ml, and acetic acid-5ml), embedded in paraffin and stained with hematoxylin and eosin. The cuts were viewed under a light microscope (100X) with a clear chamber. The nucleus of the studied tissue cells were projected on paper with a final increase of 100X. Fifty nuclei from each structure were outlined with a black pencil so that the greater (D) and smaller (d) diameters could be measured. After determining the diameters, the following cariometric parameters were established: mean geometric diameter, D/d relation, perimeter, area, volume, volume/area relation, eccentricity, form coefficient, and contour index. This study also used a grid printed on paper. The images obtained were drawn over the grid, which was used to count points over a certain histological structure as well as to count intersections between two contiguous structures. All that was needed, in the first case, was to consider the number of points located over the studied structure, or, in the second case, the number of times that neighboring surfaces cut the curve line. With the aim to evaluate the cytoplasmic volume, cellular volume, cytoplasm/nucleus relation, cellular numeric density, external surface/basal layer relation, the thickness of epithelial layers, and surface density, point counting was used at times and, at others, the number of intersections was considered and applied to the appropriate stereological equations for each variable. All the collected data were subjected to non-parametric statistics Wilcoxon-Mann-Whitney Test. The nuclei of the studied tissues showed reduced values after cariometry for: greater, smaller, and mean diameter; volume; area; perimeter; and volume/area relation. Stereologically, it was observed, in the junctional epithelium, adamantine epithelium, and in the inserted gum epithelium, cells with less volume and with scarce cytoplasm, which caused a greater number of cells per mm3 of tissue. The periodontal ligament was also disorganized and with smaller fibers. In this study, cobalt caused epithelial hypertrophy symptoms, indicating a direct action on the junctional and adamantine epithelium, inserted gum epithelium, as well as on the periodontal ligament.
Sakita, Alan Massayuki Perdizio [UNESP]. "Filmes de 'CO' obtidos por deslocamento galvânico e suas propriedades magnéticas." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/110710.
Full textEste trabalho aborda a deposição de cobalto sobre zinco utilizando a técnica de deslocamento galvânico. Inicialmente foi feito um estudo detalhado do zinco nas diversas condições em que foram depositados os filmes de cobalto. Os filmes de cobalto foram sintetizados em banhos de cloreto e sulfato com e sem glicina em pH 3 e 5 e analisados por SEM, MO, EDXS, XDR e VSM. Durante o processo de deposição foi monitorado o potencial em circuito aberto e adicionalmente foram realizadas medições de espectroscopia de impedância eletroquímica com a finalidade de elucidar os possíveis processos que ocorrem durante a deposição. Os filmes de cobalto obtidos mostram que a adição de glicina resulta numa deposição mais homogênea e sem a formação de produtos secundários como Zn5(OH)8Cl2.2H2O e Zn4(SO4)(OH)6.4H2O. A adição da glicina ainda revela uma maior evolução de hidrogênio no sistema, possivelmente relacionada à desprotonação do íon glicinato. O estudo eletroquímico do processo de deposição através de medições de potencial em circuito aberto revela maior estabilidade de potencial com a utilização de glicina no banho. O monitoramento da deposição de cobalto utilizando EIS mostra que os íons Co2+ facilitam o processo de dissolução de Zn. Com o aumento da concentração de glicina e do tempo de deposição aumenta os valores de capacitância da dupla camada elétrica e diminui a resistência à transferência de carga, sugerindo que ambas variáveis induzem o crescimento da área do eletrodo. As medidas das propriedades magnéticas mostram uma maior deposição de material metálico magnético em pH 3 em cloreto e sem a utilização de glicina, sendo que com a adição da mesma foi observado maior quantidade de cobalto metálico depositado em pH 5. Já em sulfato observa-se maior deposição de cobalto metálico na presença e ausência de glicina ambos em pH 5.
This work comprises the cobalt deposition onto zinc by using the galvanic displacement technique. The cobalt films were prepared from chloride and sulfate baths with and without glycine, and at pH 3 and 5. The deposits were characterized by: SEM, OM, EDXS, XRD and VSM. During the deposition process, it was monitored the open circuit potential and subsequently were conducted electrochemical impedance spectroscopy (EIS) measurements in order to elucidate the possible processes that may occur during the galvanic deposition. The results showed that the glycine addition leads to a more homogeneous deposition and no byproducts, such as Zn5(OH)8Cl2.2H2O and Zn4(SO4)(OH)6.4H2O, are formed. Furthermore, the glycine addition to the bath revealed a higher hydrogen evolution during the deposition process, possibly related to the deprotonation of glycinate ion. The electrochemical study of the galvanic displacement process by measuring the open circuit potential revealed a higher potential stability when glycine was employed in the bath. The monitoring of cobalt deposition by EIS showed that the Co2+ ions facilitate the process of Zn dissolution. By increasing the glycine concentration and the deposition time, the capacitance values, related to the double electric layer, increase and the charge transfer resistance decreases, suggesting that both parameters induce an increase in the electrode area. The magnetic properties of the Co deposits, extracted from the VSM measurements, exhibited the highest saturation magnetization for the deposit obtained from chloride bath at pH 3 without the glycine addition, indicating the presence of a higher amount of metallic Co in this condition. In the case of the sulfate bath, the highest saturation magnetization was reached for the deposits obtained at pH 5 in the presence of glycine.
Marcos, Francielle Candian Firmino. "Estudo de catalisadores de cobalto suportados em matrizes de La2O3-CeO2-SiO2 para a produção de hidrogênio a partir da reforma a vapor do etanol." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-10102012-142141/.
Full textThis research reports studies with Co/SiO2 catalysts modified with La2O3 and CeO2 by steam reforming of ethanol (SRE) in order to increase the catalytic activity and reduce the carbon formation on the catalyst. The amount of Co used was 10%, already of La and Ce were 10% CoLaxCe50-xSi50, where X = 2%, 4% and 6%. The supports were prepared according co-precipitation and impregnation methods in order to evaluate the effect on the catalytic performance. The active phase was incorporated by impregnation method. All were characterized by Energy Dispersive X Ray Spectroscopy (EDX), X Ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and Specific Surface Area (BET) and those prepared by co-precipitation were also analyzed by X Ray Diffraction in Situ. Thereafter, the catalysts were applied in the SRE and the highest selectivity against H2 in each method was selected for studies of variation of the mass content of active phase (10% and 20%) and temperature reaction. The performance was compared with catalysts without additive in the holder. After tests, the coke formed was determined by Elemental Analysis and characterized by Scanning Electron Microscopy (SEM) and XRD. From the XRD and TPR results was possible identify the presence of Co3O4 phase in all catalysts. In the mixed catalyst (Co/Ce-La-Si) was identified, by XRD, the formation of solid solutions between the cerium and lanthanum. Was observed that the catalyst with higher concentrations of La3+, in both methods of preparation, were more selective against H2, furthermore the temperature affected the performance of the catalysis. After characterization and quantification of the produced carbon during SRE, only catalysts supported in pure La2O3, for both methods, showed the formation of La2O2CO3, which minimizes coke formation and was identified by XRD. Through of SEM analysis of the catalyst after the reaction, it was found that coke formed a filamentous-like structure, allowing the exposure of the metallic cobalt for a longer period of time with the support.
Sader, Ana Paula de Oliveira. "Estudo espectrofotométrico do sistema cobalto(II)/tiocianato e seu aproveitamento analítico." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-19102006-204125/.
Full textStudies about the formation of metallic complexes, their equilibria and also the analytical utilization of these different systems represent a traditional research line in Chemistry. More specifically, the species formed among the various pseudohalides and other ligands, with several cations of transition metals, have been systematically investigated in our Laboratories. The use of the thiocyanate ion as ligand has been intensive from among the analytical methods for cobalt(II) determination, of which interest has increased more recently, according to the man discovers and production of new materials containing this metal. Due some typical characteristics of the system Co(II)/SCN-, such as its colored complexes, the principal purpose of this study was to explore it more carefully by visible-ultraviolet spectrophotometry. Consequently, several parameters involved in the cobalt(II)/thiocyanate complexes formation, such as acidity level, concentration of free ligand, and the percentage of organic solvents in the system, had their respective effects evaluated individually. Through the results of these diverse studies, appropriate experimental conditions were established for the analytical methods, for the determination of the cobalt(II) ion. They are: C (HClO4)=0.050 mol L-1 C (SCN-)=0.203 mol L-1 C(THF)=60% (v/v) Preliminary spectrophotometry studies showed two absorption maxima (peaks) under these optimized experimental conditions: 316 and 622 nm, being this last visible band normally applied for this type of work (determination). Calibration studies at these two wavelengths showed that the Beers Law is obeyed in both cases, but a higher sensitivity was obtained in the ultraviolet region ( E(316nm)= 1.20 x 104 e E(622nm)= 1.95 x 103 L mol-1 cm-1). Other studies about stability, precision, accuracy and possible interferences were also performed, showing satisfactory results for the analytical purposes. It was observed some interference of the following species: I-, Al3+, IO3-, Mn2+, NO2-, BrO3-, S2O32-, Hg2+ and Cd2+, when present in concentrations one hundred times higher than the cobalt(II). However, this effect disappears when these ions are presented on concentration just ten times higher. Analytical applications of the proposed method were tested for a pharmaceutical product (B12 vitamin) and for an odontological alloy, with large success, since the percentage of error was within the tolerance range (<5%). Atomic absorption spectroscopy was also used in this analysis for comparision, in which the cobalt determination was possible for the alloy but inadequate for the pharmaceutical product (error about 20%). Comparison of the results shows the potentiality of this alternative spectrophotometric method, taking in account its simplicity, accuracy and equipments prices. Finally, the influence of nickel (naturally present in several real samples) on the spectrophotometric cobalt determination was evaluated, under the optimized experimental conditions. It was observed that this natural contaminating exhibits an absorption peak at 245 nm. Other confirmatory studies show the additivities of the respective absorbances (nickel and cobalt/thiocyanate complexes), allowing the simultaneous spectrophotometric determination of these these metals, using a matematical system with two equations (peaks 245 and 316 nm). This attempt was well satisfactory and the useful concentration ranges for cobalt and nickel were, respectively, 0.94 to 4.04 mg L-1 and 28.7 to 123.7 mg L-1.
Sakita, Alan Massayuki Perdizio. "Filmes de 'CO' obtidos por deslocamento galvânico e suas propriedades magnéticas /." Araraquara, 2014. http://hdl.handle.net/11449/124433.
Full textCo-orientador: Rodrigo Della Noce
Banca: Hercilio Gomes de Melo
Banca: Roberto Zenhei Nakazato
Resumo: Este trabalho aborda a deposição de cobalto sobre zinco utilizando a técnica de deslocamento galvânico. Inicialmente foi feito um estudo detalhado do zinco nas diversas condições em que foram depositados os filmes de cobalto. Os filmes de cobalto foram sintetizados em banhos de cloreto e sulfato com e sem glicina em pH 3 e 5 e analisados por SEM, MO, EDXS, XDR e VSM. Durante o processo de deposição foi monitorado o potencial em circuito aberto e adicionalmente foram realizadas medições de espectroscopia de impedância eletroquímica com a finalidade de elucidar os possíveis processos que ocorrem durante a deposição. Os filmes de cobalto obtidos mostram que a adição de glicina resulta numa deposição mais homogênea e sem a formação de produtos secundários como Zn5(OH)8Cl2.2H2O e Zn4(SO4)(OH)6.4H2O. A adição da glicina ainda revela uma maior evolução de hidrogênio no sistema, possivelmente relacionada à desprotonação do íon glicinato. O estudo eletroquímico do processo de deposição através de medições de potencial em circuito aberto revela maior estabilidade de potencial com a utilização de glicina no banho. O monitoramento da deposição de cobalto utilizando EIS mostra que os íons Co2+ facilitam o processo de dissolução de Zn. Com o aumento da concentração de glicina e do tempo de deposição aumenta os valores de capacitância da dupla camada elétrica e diminui a resistência à transferência de carga, sugerindo que ambas variáveis induzem o crescimento da área do eletrodo. As medidas das propriedades magnéticas mostram uma maior deposição de material metálico magnético em pH 3 em cloreto e sem a utilização de glicina, sendo que com a adição da mesma foi observado maior quantidade de cobalto metálico depositado em pH 5. Já em sulfato observa-se maior deposição de cobalto metálico na presença e ausência de glicina ambos em pH 5.
Abstract: This work comprises the cobalt deposition onto zinc by using the galvanic displacement technique. The cobalt films were prepared from chloride and sulfate baths with and without glycine, and at pH 3 and 5. The deposits were characterized by: SEM, OM, EDXS, XRD and VSM. During the deposition process, it was monitored the open circuit potential and subsequently were conducted electrochemical impedance spectroscopy (EIS) measurements in order to elucidate the possible processes that may occur during the galvanic deposition. The results showed that the glycine addition leads to a more homogeneous deposition and no byproducts, such as Zn5(OH)8Cl2.2H2O and Zn4(SO4)(OH)6.4H2O, are formed. Furthermore, the glycine addition to the bath revealed a higher hydrogen evolution during the deposition process, possibly related to the deprotonation of glycinate ion. The electrochemical study of the galvanic displacement process by measuring the open circuit potential revealed a higher potential stability when glycine was employed in the bath. The monitoring of cobalt deposition by EIS showed that the Co2+ ions facilitate the process of Zn dissolution. By increasing the glycine concentration and the deposition time, the capacitance values, related to the double electric layer, increase and the charge transfer resistance decreases, suggesting that both parameters induce an increase in the electrode area. The magnetic properties of the Co deposits, extracted from the VSM measurements, exhibited the highest saturation magnetization for the deposit obtained from chloride bath at pH 3 without the glycine addition, indicating the presence of a higher amount of metallic Co in this condition. In the case of the sulfate bath, the highest saturation magnetization was reached for the deposits obtained at pH 5 in the presence of glycine.
Mestre
Nik, Mohd Masdek Nik Rozlin. "Electrodeposition and corrosion study of nanocrystalline cobalt and cobalt-iron alloy coatings." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/49944.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Chen, Ming-Chou. "Metallacyclobutenes as reactive intermediates : conversion to cobalt diene and cobalt allene complexes /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9834967.
Full textFoelske, Annette. "Oberflächenanalytische Untersuchungen zur anodischen Deckschichtbildung auf Kobalt- und Co(0001)-Einkristallelektroden." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970112378.
Full textÖnem-Siakou, Evgenia. "Cobalt(III)-Kohlenhydrat-Verbindungen." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-33130.
Full textKim, S. S. "Cobalt catalysed oxidation reactions." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376060.
Full textLyu, Ye. "Cobalt-catalyzed Hydroelementation Reactions." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS611.
Full textThis thesis was focused on well-defined low-valent cobalt complexes HCo(PMe3)4/HCoN2(PPh3)3, the bench stable family Cp*Co(III) of complexes and their applications in R–H activation (R = B, C, Si). First, we successfully used the HCo(PMe3)4 complex to catalyze regio- and stereo-selective hydroboration and diboration of alkynes. In addition, we exploited the HCo(PMe3)4 complex to catalyze silaboration of alkyne. Then, we demonstrated that the HCo(PMe3)4 complex and HCoN2(PPh3)3 complex were useful in the stereo-divergent hydrogenation of alkynes. Finally, we explored the application of the bench- stable Cp*Co(III) together with chiral additives in asymmetrical C–H bond functionalization. In addition, we conducted the elementary exploitation in synthesis of chiral Cp*Co(III) complexes
Haffer, Stefanie [Verfasser]. "Mesoporous spinel-type cobalt oxide, cobalt ferrite and alumina by nanocasting / Stefanie Haffer." Paderborn : Universitätsbibliothek, 2014. http://d-nb.info/1046651994/34.
Full textOgrin, Feoder. "Ferromagnetic resonance studies of cobalt films and cobalt based multilayers produced by MOCVD." Thesis, Keele University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362165.
Full textGovender, Alisa. "Cobalt core-shell nanoparticles as precursors for cobalt-based Fischer-Tropsch synthesis catalysts." Doctoral thesis, Faculty of Engineering and the Built Environment, 2018. http://hdl.handle.net/11427/30007.
Full textKiviaho, Jari. "Fischer-Tropsch synthesis catalysed by cobalt-rhodium and cobalt-ruthenium carbonyl clusters on silica /." Espoo : Technical Research Centre of Finland, 1996. http://www.vtt.fi/inf/pdf/publications/1996/P290.pdf.
Full textÅkre, Torjus. "Electrowinning of Cobalt from Chloride Solutions: Anodic Deposition of Cobalt Oxide on DSA®." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2200.
Full textGourion, Louis. "Le cobalt en biologie humaine." Paris 5, 1988. http://www.theses.fr/1988PA05P080.
Full textNg, Jesse B. "Mono- and binuclear cobalt hydrides." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30789.
Full textScience, Faculty of
Chemistry, Department of
Graduate
Numprasanthai, Apisit Chemical Sciences & Engineering Faculty of Engineering UNSW. "Binary skeletal copper-cobalt catalysts." Publisher:University of New South Wales. Chemical Sciences & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43587.
Full textGuindy, Christina Irene. "Cobalt complexes of radical ligands." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408058.
Full textSaikoff, Elsa, Edvin Andersson, Felix Bengtsson, Christoffer Olausen, Monika Galstyan, David Vikström, and Byström Joseph Lazraq. "Cobalt in High Speed Steels." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355124.
Full textMcCombs, Michelle. "A 59-Cobalt NMR Investigation of the Hydrogen/Deuterium Exchange Kinetics in Cobalt(III) Complexes." TopSCHOLAR®, 2003. http://digitalcommons.wku.edu/theses/554.
Full textN'Guessan, Gilbert Kouakou. "Réduction électrochimique du composé d'insertion graphite-chlorure de cobalt : étude du composé réduit graphite-cobalt." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0082.
Full textAraújo, Júnior Ildeu Bastos de. "Estudo da influência do resfriamento em revestimento de liga Stellite 6 aplicada pelo processo TIG /." Bauru :, 2009. http://hdl.handle.net/11449/96481.
Full textBanca: Gilberto de Magalh B. Gonçalves
Banca: Rodolfo Libardi
Resumo: A indústria busca uma melhor otimização e performance de seus equipamentos, há muito notou-se a importância da contenção do desgaste para o aumento de vida útil dos componentes de máquinas. Em condições operacionais onde há o desgaste por abrasão, comumente faz-se o endurecimento da camada superficial ou a aplicação de uma liga mais nobre e de dureza mais elevada, visando conter este desgaste. A técnica também é chamada de revestimento. Entender melhor os parâmetros que influenciam nos resultados da aplicação destes revestimentos torna-se importante possibilitando menores perdas e uma maior economia, pois busca-se como alvo trabalhar com a melhor performance do revestimento. Objetivou-se neste trabalho o estudo das ligas a base de Cobalto que são aplicadas cada vez mais rotineiramente nas indústrias petroquímicas, onde os componentes e órgãos de máquinas estão expostos a condições severas de desgaste por abrasão e corrosão além da severidade dos trabalhos a altas temperaturas e pressão. Relacionando o desgaste, as ligas a base de Cobalto possuem uma posição destacada e a liga é conhecida comercialmente como "Stellite 6". Em alguns trabalhos é chamada também de liga coringa por sua versatilidade e destaque em especial. Neste trabalho procurou-se variar as velocidades de resfriamento em cinco patamares, analisou-se a influência da diluição na micro-dureza e os efeitos da variação da velocidade de resfriamento no mecanismo de endurecimento. A aplicação do revestimento ocorreu em três camadas através do processo TIG. Verificamos ainda a interferência da diluição na dureza em cada camada de revestimento. A terceira e última camada foi a que apresentou maior dureza devido à menor diluição com o metal base principalmente no corpo de prova que possuía à menor velocidade de resfriamento devido ao tempo para a formação de precipitados e carbonetos na liga metálica
Abstract: The industry searchs a better optimization and performance of their equipment, long noted the importance of containment to increase the wear life of components of machines. In operating conditions where there is wear by abrasion, usually it is the hardening of the surface layer or the application of a more noble alloy and high hardness, wear it to contain. The technique also called hardfacing. Better understand the parameters that influence the results of applying these coatings becomes important because it enables lower losses and greater economy as it seeks to target work with the best performance of the coating. The objective of this research is complements the study of cobalt-based alloys that are applied more routinely in petrochemical industries, where the component units and machines are exposed to severe conditions of wear by abrasion and corrosion than the severity of the work at high temperatures and pressure. Relating the wear, the cobalt-based alloys have a prominent position and the league is known commercially as "Stellite 6". Some work is also called the league wildcard for its versatility and highlight in particular. In this work we have tried to vary the speed of cooling in five steps, looked up the influence of dilution on micro hardness and the effects of variation in the rate of cooling in the hardening mechanism. The application of the coating occurred in three layers using the TIG process. We note also the interference of dilution in hardness in each layer of coating. The third and final layer was the one with higher hardness due to less dilution with the base metal mainly in the body of evidence that had the lowest rate of cooling due to the time for the formation of precipitates and carbides in the metal
Mestre
Monteiro, Kristian. "Recycling of spent lithium nickel-cobalt batteries through leaching of nickel and cobalt from cathode material." Thesis, Monteiro, Kristian (2018) Recycling of spent lithium nickel-cobalt batteries through leaching of nickel and cobalt from cathode material. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/41912/.
Full textFirriolo, Janet Marie. "Disposition and toxicity after oral and intravenous administration of cobalt naphthenate and cobalt chloride in rats." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185760.
Full textVan, Leeuwen Robert Alan. "Structural and magnetic properties of cobalt/palladium superlattices, ultra-thin cobalt films and manganese antimony alloys." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186431.
Full textLussier, Alexandre Francois. "Ferromagnetism in cobalt-doped titanium dioxide." Diss., Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/lussier/LussierA1205.pdf.
Full textGhaschghaie, Natascha. "Heteroleptische Cobalt(III)-Chelatkomplexe mit Bioliganden." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-121266.
Full textSims, Jeffrey J. "Formic Acid Decomposition on Cobalt Surfaces." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32592.
Full textBeard, Collen Alana. "Rubredoxin cobalt substitution and crystallization attempts." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/29863.
Full textKuyucak, Nural. "Algal biosorbents for gold and cobalt." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75374.
Full textSequestered gold was eluted with a mixture of thiourea and ferric ammonium sulphate solution. Approximately 98% of sequestered gold was eluted with 17 h in a batch contacting system at the optimum solids (biomass)-to-liquid ratio of 5 and pH of 5. At increased temperatures, the gold elution rate increased only slightly. Efficient desorption of cobalt was achieved using CaCl$ sb2$/HCL solution at pH 3. Cobalt elution time was quite short. Temperature affected neither desorption rate nor the equilibrium. The optimum solid-to-liquid ratio was 12 for desorption of cobalt from A. nodosum biomass.
The gold taken up by the biosorbent was deposited in its elemental form.
Available mathematical models, including the REDEQL2 chemical equilibrium model, were tested for theoretical predictions of co-ion competition in attempt to better understand the biosorption mechanism. (Abstract shortened with permission of author.)
Jane, Reuben Thomas. "Cobalt(III) Complexes For Surface Engineering." Thesis, University of Canterbury. Chemistry, 2010. http://hdl.handle.net/10092/4424.
Full textPatel, V. F. "Cobalt-medicated radical reactions in synthesis." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380160.
Full textBeaumont, Ian R. "The chemistry of cyclopentadienyl cobalt complexes." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291970.
Full textMedforth, C. J. "Cobalt (III) porphyrin N.M.R. shift reagents." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384368.
Full textPapageorgiou, Iraklis. "The genotoxicity of cobalt-chrome particles." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431833.
Full textCracknell, R. B. "Agostic interactions at a cobalt centre." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371994.
Full textLARRUDE, DUNIESKYS ROBERTO GONZALEZ. "CARBON NANOTUBES DECORATED WITH COBALT PARTICLES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10465@1.
Full textOs nanotubos de carbono desde seu descobrimento têm atraído crescentemente a atenção devido a sua estrutura original e propriedades eletrônicas únicas. Encontrando muitas possíveis aplicações, como na área de materiais suportes para catálise, dada sua grande área superficial e boa condutividade elétrica quando comparado aos materiais convencionais à base de carbono. Essas características favorecem uma maior dispersão e estabilização de nanopartículas metálicas o que propicia o acceso a um número maior de átomos cataliticamente ativos. Neste trabalho foram produzidos nanotubos de carbono de paredes múltiplas de uma boa qualidade estrutural utilizando o método de Spray Pyrolysis. Foram encontrados os parâmetros de crescimento ideais de nosso sistema tais como fluxo de gás e faixa de valores para a concentração da solução precursora, 1800 sccm e 2,0-2,9% em peso, respectivamente. Os nanotubos foram decorados com partículas de cobalto através de uma rota química sendo o processo mais eficiente o que envolve a dissolução do nitrato de cobalto em acetona para a formação de um pó homogêneo de nanotubos-oxido de cobalto para sua posterior redução em atmosfera de H2 a 573 K. A qualidade estrutural dos nanotubos produzidos bem como do material decorado foi avaliado através de diferentes técnicas de caracterização tais como espectroscopia Raman, microscopia eletrônica de varredura e de transmissão, e difração de raios-X.
Carbon nanotubes since they are observed for the first time have been attracted attention due to their structure and unique electronic properties. Many applications, as support materials for catalysts, are proposed because of their aspect ration and good electrical conductivity. These properties favor a better dispersion and stabilization of the metallic nanoparticles, increasing the number of catalytic active atoms. In this work, we produced multi- walled carbon nanotubes (MWNT) with good structural properties using the Spray Pyrolysis method. We found the optimum parameters for the growth of high quality MWNT, namely, the gas flux and the concentration of the precursor solution, 1800 sccm and 2,0-2,9 wt %, respectively. The nanotubes were decorated via a chemical route, being the most efficient process the one where the cobalt nitrate was diluted in acetone with the formation of a homogeneous cobalt oxide particles-MWNT powder, with a subsequent reduction in H2 atmosphere at 573K. The structural characterization was performed by a multitechnique approach, including Raman spectroscopy, transmission and scanning electron microscopes (TEM and SEM) and x-ray diffraction (XRD).
McAulay, Kate. "Cobalt rhenium catalysts for ammonia synthesis." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8421/.
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