Дисертації з теми "Co-base alloys"
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SILVA, SUELANNY C. da. "Estudo da influência da temperatura nas propriedades magnéticas e na microestrutura nos imãs permanentes à base de Pr-Fe-B-Nb-Co obtidos com hidrogênio." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11612.
Повний текст джерелаMade available in DSpace on 2014-10-09T13:58:57Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Silva, Suelanny Carvalho da. "Estudo da influência da temperatura nas propriedades magnéticas e na microestrutura nos ímãs permanentes à base de Pr-Fe-B-Nb-Co obtidos com hidrogênio." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-24102011-104115/.
Повний текст джерелаFine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900°C with the purpose of optimizing the HDDR treatment for Pr14Fe80B6 and Pr14FebalCoxB6Nb0,1 (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100°C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880°C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840°C and 820°C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840°C. The optimum desorption temperature for achieving high anisotropy for Pr14Fe80B6 and Pr14Fe79,9B6Nb0,1 was 820°C. The best remanence (862mT) was achieved with the Pr14Fe67,9B6Co12Nb0,1 magnet, processed at 840°C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr14Fe80B6 HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy (SEM) has also been employed to reveal the morphology of the HDDR powder.
Hunter, Elizabeth Adele Outdoor. "The smallest base and precious metal deposits in the world : vapor transport and deposition of bronze-Co-Ag alloys in vesicles /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1932.pdf.
Повний текст джерелаHunter, Elizabeth Adele Outdoor. "The Smallest Base and Precious Metal Deposits in the World: Vapor Transport and deposition of Co-Cu-Sn-Ag alloys in vesicles." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1406.
Повний текст джерелаWang, Jun. "Alliages base Cobalt en surfusion sous champ magnétique intense : propriétés magnétiques et comportement à la solidification." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00870412.
Повний текст джерелаDupin, Nathalie. "Contribution à l’évaluation thermodynamique des alliages polyconstitués à base de nickel." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0040.
Повний текст джерелаNaujoks, Dennis [Verfasser], Alfred [Gutachter] Ludwig, and Gunther [Gutachter] Eggeler. "Application of combinatorial materials science methods to model alloys for the understanding of phase stabilities, oxidation behavior and atomic mobility in Ni- and Co-base superalloys / Dennis Naujoks ; Gutachter: Alfred Ludwig, Gunther Eggeler ; Fakultät für Maschinenbau." Bochum : Ruhr-Universität Bochum, 2019. http://d-nb.info/1212664078/34.
Повний текст джерелаBen, Mbarek Wael. "Synthèse, caractérisation et application des alliages à base de Mn-X-Y (X=Al; Y=Fe,Co) et Ca-Al dans la dégradation d'un colorant azoïque "Black 5" utilisé dans l'industrie de textile." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/666563.
Повний текст джерелаAquest treball s'enmarca en el context general de la síntesi i caracterització d'aliatges de base Mn o Ca que són utilitzats en processos de degradació de colorants azo habitualment emprats en les indústries tèxtils. Els aliatges han estat produïts essencialment per tres tècniques: fusió per arc (arc melting), refredament ràpid en una roda giratòria (melt spinning) per a la producció de cintes i mòlta mecànica (ball milling) per a la producció de pols. El baix valor de l'energia d'activació i la ràpida cinètica de degradació fa que els aliatges del sistema Mn-Al siguin candidats a ser utilitzats en el tractament de decoloració d'aïgues residuals industrials. S'ha analitzat l'addició de Fe o Co. La baixa resistència a la corrosió del Fe augmenta la velocitat de la reacció de degradació. Per altra banda, els resultats obtinguts en el sistema Ca-Al mostren que són agents reductors efectius en condicions de pH neutre
Vermeulen, Jean-Luc. "Elaboration par pulvérisation ionique et caractérisation de couches minces ferromagnétiques à forte perméabilité." Grenoble 1, 1993. http://www.theses.fr/1993GRE10071.
Повний текст джерелаAbdul-Latif, Akrum. "Approches multi-échelles pour la description de l'anélasticité avec endommagement." Compiègne, 1994. http://www.theses.fr/1994COMP678S.
Повний текст джерелаBouzaher, Abdallah. "Réseau bipériodique de dislocations d'hétéro-interface en élasticité anisotrope." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0089.
Повний текст джерелаOLIVEIRA, MARA C. L. de. "Preparacao de imas HDDR e ligas de PrFe-Co-B-Nb-M (M=Al,P,Cu,Ga e/ou Gd) e caracterizacao de suas propriedades magneticas e resistencia a corrosao." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11783.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:05:18Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Wuchner, Sip Sibylle. "Etude des processus d'aimantation de tri-couches magnétiques à base d'alliages amorphes de terres rares et de cobalt." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10070.
Повний текст джерелаÖrnberg, Andreas. "Study of Electrochemical Behaviour and Corrosion Resistance of Materials for Pacemaker Lead Applications." Licentiate thesis, KTH, Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4650.
Повний текст джерелаFor patients suffering bradycardia, i.e., too slow heart rhythm, the common treatment is having a pacemaker implanted. The pacemaker system consists of the pacemaker and a pacing lead. The pacing lead is connected to the pacemaker and at the other end there is a stimulation electrode. The most common conductor material is a cobalt-based super alloy (MP35N® or 35N LT®), with the main constituents Ni, Co, Cr and Mo. The pacemaker electrode is often made of a substrate material with a rough surface coating. The substrate materials are predominantly platinum/iridium alloy and titanium. The material choice is of great importance for the performance and stability during long-term service. Excellent corrosion resistance is required to minimize elution of metal ions in the human body.
In this thesis, the electrochemical behaviour and corrosion resistance of the Co-based alloys and Ta (as electrode substrate), in a phosphate buffer saline (PBS) solution with and without addition of H2O2, was investigated by means of potentiodynamic polarization, cyclic voltammetry, electrochemical impedance spectroscopy and simulated pacemaker pulsing. The metal release from the Co-based alloy during the passivation treatment and exposure in the synthetic biological media was measured by using inductive coupled plasma - atomic emission spectroscopy (ICP-AES). Moreover, surface composition was analyzed by using x-ray photoelectron spectroscopy.
The results show that the chemical passivation of Co-based alloy 35N LT® increased the corrosion resistance and reduced Co release significantly, even in more hostile environment, i.e. PBS with addition of H2O2. The increased corrosion resistance is due to the Cr enrichment in the surface layer. The reduced Co release is due to a preferential dissolution of Co from the surface oxide layer during the chemical passivation. The electrochemical investigation of uncoated and rough TiN coated Ta show that uncoated Ta is not suitable electrode material due to formation of a highly resistive surface oxide film. Whereas the rough TiN coated Ta exhibits desirable electrochemical performance for pacemaker electrodes. The addition of H2O2 in the PBS has a large influence on the electrochemical behaviour of Ta, but the influence is small on the rough TiN coated Ta.
Royer, Agnès. "Evolutions thermique et mécanique de la microstructure de superalliages monocristallins étudiées par diffusion centrale et diffraction (neutrons, rayons [gamma])." Grenoble 1, 1993. http://www.theses.fr/1993GRE10097.
Повний текст джерелаBessoud, Agnès. "Analyse des interactions dans des alliages à base de métaux de transition." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0091.
Повний текст джерелаDe, Pauw Virginie. "Mécanismes de nitruration et d'oxydation du composé intermétallique Sm2 (Fe, Co)1#7 pour aimants permanents." Rouen, 1996. http://www.theses.fr/1996ROUES053.
Повний текст джерелаChambreland, Sylvain. "Etude des premiers stades de précipitation dans un superalliage à base de nickel à l'aide d'une sonde atomique." Rouen, 1987. http://www.theses.fr/1987ROUES055.
Повний текст джерелаPeng, Lu. "Metal Nanoparticles Wrapped on Defective Nitrogen-doped Graphitic Carbons as Highly Selective Catalysts for C02 Hydrogenation." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/172329.
Повний текст джерела[CA] Tenint en compte l'esgotament dels combustibles fòssils i la creixent concentració de CO2 en l'atmosfera, la hidrogenació de CO2 és una forma prometedora de convertir el CO2 en productes químics i combustibles de carboni d'alt valor afegit. Considerant la gran influència de la grandària de partícula, la composició química, la naturalesa del suport i les condicions d'operació sobre el comportament catalític dels catalitzadors, s'han desenvolupat una sèrie de catalitzadors per a la hidrogenació de CO2 basats en metalls abundants no nobles i polisacàrids naturals com a precursors del grafé. En la present tesi doctoral, les espècies metàl·liques suportades sobre una matriu de carboni grafític defectuosa, amb diferents grandàries de partícules, mostren diferent activitat catalítica i selectivitat per a la hidrogenació de CO2. Es van preparar, de manera controlada, nanopartícules d'aliatges de Co i Co-Fe suportades en grafens dopats amb N defectuosos, amb una àmplia distribució de grandària de nanopartícules, per a la reacció de Sabatier, presentant una selectivitat a metà superior al 90% amb valors de conversió de CO2 superiors al 85%. En el cas d'un sol metall, Co o Fe, i els seus aliatges en forma de "clústers" i xicotetes nanopartícules suportades en el mateix material, la selectivitat de la hidrogenació de CO2 canvia a CO, en lloc de metà, obtenint-se un valor del 98% i aconseguint una conversió de CO2 del 56%. Convé ressaltar que, els catalitzadors basats en "clústers" d'aliatges de metall amb una càrrega de metall fins i tot per davall del 0.2% en pes, exhibeixen una major selectivitat i rendiment que els que tenen nanopartícules d'aliatges de Co-Fe més grans que varien d'1 a 4 nm i una càrrega de metall més alta en una composició similar. Seguint la línia d'investigació d'hidrogenació de CO2, es van desenvolupar una sèrie de nanopartícules d'aliatges de Co-Fe suportades sobre grafens dopats amb N defectuosos amb distribució de grandària de nanopartícules controlada en el rang de 7-17 nm, obtenint una selectivitat cap a hidrocarburs C2+ al voltant del 45% i una conversió del CO2 pròxima al 60%. A més, es va realitzar un estudi comparatiu de l'activitat catalítica de catalitzadors similars basats en Co-Fe amb promotors i inhibidors per a la hidrogenació de CO2, observant la seua influència en la conversió i selectivitat de CO2. Finalment, a més dels catalitzadors basats en Co-Fe, també s'han preparat catalitzadors basats en Cu-ZnO mitjançant un mètode de dos passos. Aquestes nanopartícules de Cu-ZnO suportades sobre grafé defectuós dopat amb N exhibeixen una alta selectivitat cap a la conversió de CO2 a metanol.
[EN] Considering the depletion of fossil fuels and the increasing atmospheric CO2 concentration, CO2 hydrogenation is a promising way to convert CO2 into value-added carbon-containing chemicals and fuels. Taking into account the significant influences of the particle size, chemical composition, nature of the support, and operation conditions on the catalytic performance of catalysts, a series of catalysts for CO2 hydrogenation have been developed based on the use of abundant non-noble metals and natural polysaccharides as graphene precursors. In the present PhD Thesis, metal species supported on defective graphitic carbon matrix with different particle sizes show different catalytic activity and selectivity for CO2 hydrogenation. Under effective control, Co and Co-Fe alloy nanoparticles wrapped on defective N-doped graphenes with a broad nanoparticle size distribution were prepared and performed for the Sabatier reaction, exhibiting a selectivity to methane over 90 % at CO2 conversion values over 85 %. In the case of single Co or Fe metal and their alloys in the form of clusters and small nanoparticles wrapped on the same support, the selectivity for CO2 hydrogenation shifts to CO, rather than methane, reaching a conversion of 56 % with 98 % CO selectivity. It is worth noting that the metal alloy clusters-based catalysts with the metal loading even below 0.2 wt.% exhibit a higher selectivity and better performance than the ones with larger Co-Fe alloy nanoparticles ranging from 1-4 nm and higher metal loading in a similar composition. Following the research line for CO2 hydrogenation, a series of Co-Fe alloy nanoparticles supported on defective N-doped graphenes with controlled nanoparticle size distribution in the range of 7-17 nm are developed, obtaining a selectivity towards C2+ hydrocarbons about 45% with a CO2 conversion close to 60%. In addition, a comparative catalytic activity of similar Co-Fe-based catalysts with promoters and poison has been studied for CO2 hydrogenation to observe their influence on CO2 conversion and selectivity. Finally, besides Co-Fe-based catalysts, Cu-ZnO-based catalysts have also been prepared by a two-step method. These Cu-ZnO nanoparticles supported on N-doped defective graphene exhibit a high selectivity for CO2 conversion to methanol.
Peng, L. (2021). Metal Nanoparticles Wrapped on Defective Nitrogen-doped Graphitic Carbons as Highly Selective Catalysts for C02 Hydrogenation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172329
TESIS
XU, GUO-FENG, and 許國峰. "Planar flow casting method crystallization behaviour for the Fe-and Co-base amorphous alloys." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/07917738485667346501.
Повний текст джерелаSU, YUNG-CHUAN, and 蘇永川. "The Study of Mechanical Properties of Co-base Alloy Coatings Sprayed by HVOF and Zirconia Ceramic Coatings Sprayed by APS." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/spj98x.
Повний текст джерела國立高雄應用科技大學
機械工程系
106
For the purpose of improving operational efficiency of combined cycle plants, increasing the inlet fuel gas temperature of gas turbines has become the international trend of power plants development nowadays. However, while under the influence of elevated temperatures and hot corrosion environment, hot section components are rapidly in a performance degradation and even crack. The characteristics of ceramics of Thermal Barrier Coating(TBC) at thermal durability and thermal insulation, not only can increase the inlet fuel gas temperature of gas turbines but also reduce the surface temperature of substrates.On top of that, it may also enhance the thermal efficiency of plant units and prolong the plant service life. This research emphasizes on investigating two substrates,SUS304 and Hastelloy X, applying with High Velocity Oxygen fuel System (HVOF) thermal spraying MCrAIY alloy bond coat and with APS thermal spraying ZrO2-Y2O3 Zirconia ceramic as top coat to form Thermal Barrier Coating(TBC).We used Optical and Scanning Electron Microscope (SEM) to observe coating of microstructures, including the thickness of coating, porosity, oxide, crack and unmelted particle. Furthermore, we used X-ray Energy Dispersive Spectroscopy, X-ray Diffraction and Micro-hardness Test in order to compare the difference of micro-structures and mechanical properties on coating of two specimens. The experiment result has revealed that both of coating specimens have no obvious degradation; coating and bonding strength are in quite good performance and no coating spallation situation. In addition, MCrAIY alloy coating by HVOF has higher micro-hardness value, which average value is about1.25~1.50 times than the one coating by APS. HVOF, since with high speed in-flight powder particles hitting the substrate in high velocity, it may form the coating with characteristics of high bonding strength, high hardness and high density. On the other hand, the coating by APS has much loose structure and relatively more voids. Thus, due to the high porosity, the characteristics of thermal insulation and thermal shock resistance of coating are being promoted.