Дисертації з теми "Alloy layer"
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Taylor, Matthew Logan. "Hydrogen permeation of Alloy-22 considering the passive layer." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446439.
Повний текст джерела
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SOUTO, MARCELO BELMIRO GOMES DE. "CHARACTERIZATION OF THE OXIDIZED LAYER OF ALLOY ASTM F15 OBTAINED UNDER DIFFERENT SURFACE CONDITIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25671@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A liga ASTM F15 é usada para o encapsulamento de componentes ou dispositivos eletrônicos em virtude de seu baixo coeficiente de expansão térmica que é similar à de vidros duros. Na construção de juntas vitro metálicas com características de hermeticidade a formação de uma camada de óxido na superfície metálica é necessária para que ocorra o molhamento adequado desta superfície pelo sealing glass. Neste trabalho foram utilizados dois tipos de superfícies, subdivididos em grupos, de modo a avaliar a sua influência na formação da camada oxidada. As superfícies foram oxidadas à temperatura de 800 graus C, em atmosfera ambiente, variando o tempo de oxidação em 5, 10, 20 e 40 minutos, seguido de resfriamento ao ar. As camadas de óxido foram caracterizadas quanto a sua morfologia e composição química, utilizando Microscopia Eletrônica de Varredura (MEV), Microscopia Ótica (MO), Difração de Raio X (DRX) e Espectroscopia de emissão e fótons de raio X (XPS) e Rugosimetria. As camadas de óxido foram avaliadas em função do ganho de massa superficial, espessura, composição química e rugosidade da superfície metálica. Os principais produtos de oxidação, nas condições estudadas foram Hematita (Fe2O3), Magnetita (Fe3O4) e Taenita (FeNi). Foi observado que e as condições superficiais de rugosidade não influenciaram o tipo de produtos de oxidação obtido, porém se obteve maiores ganhos de massa para as superfícies polidas mecanicamente.
The alloy ASTM F15 is used for the encapsulation of components or electronic devices because of its low coefficient of thermal expansion that is similar to hard glasses. In construction joints glass-to-metal tightness with characteristics forming an oxide layer on the metallic surface is required so that adequate wetting takes place at the surface of this sealing glass. This study looked at two types of surfaces, subdivided into groups in order to assess their influence on the oxide layer. One group was subjected to mechanical polishing and the other group subjected to chemical polishing. The surfaces were oxidized at a temperature of 800 degrees C in the ambient atmosphere by varying the oxidation time at 5, 10, 20 and 40 minutes, followed by cooling to air. As oxide layers were characterized for their morphology and chemical composition, using Scanning Electron Microscopy (SEM), Optic Microscopy, X-Ray Diffraction (XRD) and Emission spectroscopy and X-ray photons (XPS) and Rugosimeter.The oxide layer was evaluated in terms of surface mass, thickness, chemical composition and surface roughness of the metal surface. The main oxidation products under the conditions studied were Hematite (Fe2O3), Magnetite (Fe3O4) and Taenita (FeNi). It was observed that, surface roughness conditions did not influence the type of oxidation products obtained, but it had greater mass gains for the mechanically polished surfaces.
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Zhao, Zhijun. "Role of surface active layers on localized breakdown of aluminum alloy 7075." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1160670830.
Повний текст джерела
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Hazlehurst, Kevin Brian. "The adoption of laser melting technology for the manufacture of functionally graded cobalt chrome alloy femoral stems." Thesis, University of Wolverhampton, 2014. http://hdl.handle.net/2436/332114.
Повний текст джерелаАнотація:
Total Hip Arthroplasty (THA) is an orthopaedic procedure that is performed to reduce pain and restore the functionality of hip joints that are affected by degenerative diseases. The outcomes of THA are generally good. However, the stress shielding of the periprosthetic femur is a factor that can contribute towards the premature loosening of the femoral stem. In order to improve the stress shielding characteristics of metallic femoral stems, stiffness configurations that offer more flexibility should be considered. This research has investigated the potential of more flexible and lightweight cobalt chromium molybdenum (CoCrMo) femoral stems that can be manufactured using Selective Laser Melting (SLM). Square pore cellular structures with compressive properties that are similar to human bone have been presented and incorporated into femoral stems by utilising fully porous and functionally graded designs. A three dimensional finite element model has been developed to investigate and compare the load transfer to the periprosthetic femur when implanted with femoral stems offering different stiffness configurations. It was shown that the load transfer was improved when the properties of the square pore cellular structures were incorporated into the femoral stem designs. Factors affecting the manufacturability and production of laser melted femoral stems have been investigated. A femoral stem design has been proposed for cemented or cementless fixation. Physical testing has shown that a functionally graded stem can be repeatedly manufactured using SLM, which was 48% lighter and 60% more flexible than a traditional CoCrMo prosthesis. The research presented in this thesis has provided an early indication of utilising SLM to manufacture lightweight CoCrMo femoral stems with levels of flexibility that have the potential to reduce stress shielding in the periprosthetic femur.
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Domfang, Ngnekou Julius-Noël. "Étude expérimentale de la tenue en fatigue de l’alliage AlSi10Mg élaboré par fusion laser de lit de poudre Influence of as-built surface and heat treatment on the fatigue resistance of Additively Layer Manufacturing (ALM) AlSi10Mg alloy Fatigue resistance of selectively laser melted aluminum alloy under T6 heat treatment Fatigue properties of AlSi10Mg produced by Additive Layer Manufacturing." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0015.
Повний текст джерелаАнотація:
Ce travail montre l'impact des défauts et de la microstructure sur la limite de fatigue de l’AlSi10Mg de fabrication additive (FA). Les échantillons d’étude sont fabriqués suivant trois orientations (0 °, 45 ° et 90 °) ; les surfaces d’étude sont usinées ou brutes de fabrication. Les éprouvettes sont étudiées avec ou sans traitement thermique T6. Avant toute chose, le matériau est d’abord caractérisé en lien avec les paramètres du procédé à l’aide de plusieurs moyens (microscopie, microtomographie). Du point de la fatigue, les courbes S-N sont établies avant et après T6, principalement à R = -1 en sollicitation uniaxiale. Pour toutes les éprouvettes d’étude, l’analyse des faciès montre que ce sont toujours les défauts qui sont à l’origine de la rupture par fatigue. Ainsi, un critère est appliqué pour définir ces défauts critiques (type, taille morphologie et position) et la limite de fatigue est systématiquement analysée via les diagrammes de Kitagawa. Le rôle de la direction de construction sur la tenue en fatigue est étudié, avant et après traitement thermique T6, tant pour les surfaces usinées que brutes de fabrication. À cet effet, un scénario basé sur la taille caractéristique des grains est proposé pour expliquer les effets d’orientation post-T6. La contribution de la structure de précipitation est également étudiée ; ainsi que le rôle des défauts (type, taille, morphologie et position) sur la limite de fatigue à différents états microstructuraux : avant et après T6. Afin de comprendre les mécanismes d’endommagement par fatigue en surface, la méthode des répliques est déployée sur une éprouvette polie. Dans ce cadre, une loi de propagation des fissures naturelles, c'est-à-dire qu'elles sont dues à un défaut hérité du procédé, est identifiée. Elle permet de séparer les phases d’amorçage et de propagation, alimentant ainsi les discussions sur les phénomènes d’amorçage en présence de défauts. Par ailleurs, quelques critères de fatigue sont également discutés et l’approche Defect Stress Gradient (DSG) est adaptée au matériau d’étude en tenant compte de la taille des grains cristallographiques. Pour les sections utiles brutes de fabrication, le rôle du mode de suppression des supports fabrication sur l’amorçage des fissures de fatigue est étudié ; la définition de la notion de taille de défauts en présence de la rugosité, à l’échelle de l’ondulation de surface, est abordée. Sachant que l’amorçage peut avoir lieu sur une ondulation de surface ou sur un défaut isolé (porosité ou défaut de fusion), une méthode expérimentale est proposée pour analyser la compétition entre ces facteurs. Dans un contexte de développement industriel, l’influence sur la limite de fatigue des paramètres de procédé relatifs au laser (vitesse de balayage, puissance et distance de hachure), au lit de poudre (composition chimique, taille des particules, épaisseur du lit) est étudiée, en vue d’alimenter les discussions vers l’optimisation du procédé du point de vue de la tenue en fatigueThis work shows the impact of defects and microstructure on the fatigue limit of AlSi10Mg produced by Additive Layer Manufacturing (ALM). Samples are produced according to three orientations with respect to the construction plate (0 °, 45 ° and 90 °); the studied surfaces are machined or left as-built (AB) in the gauge section. The specimens are studied with or without T6 heat treatment. The study surfaces are machined or as built. Some specimens are subjected to T6 heat treatment. Before any others study, the material is characterized in connection with the process parameters through several techniques (microscopes and 3D X-ray microtomography). Regarding the fatigue, the S-N curves are established before and after T6, mainly at R = -1 under uniaxial loading. For all the fatigue test specimens, fracture surfaces analysis shows that it is always a defect that cause fatigue failure. Thus, a criterion is applied to define these critical defects (type, size morphology and position) and the fatigue limit is analyzed through the Kitagawa type diagrams. The role of the building direction on the fatigue strength is studied, before and after T6 heat treatment, for both machined and as-built surfaces. For this purpose, a sketch based on the characteristic grain size is proposed to explain post-T6 orientation effects. The contribution of the precipitation structure is also studied; as well as the role of defects (type, size, morphology and position) on the fatigue limit at different microstructural states: before and after T6. In order to understand the surface fatigue damage mechanisms, the replica method is used on a polished specimen. In this context, a propagation law of natural cracks, that is to say due to a defect inherited from the process, is identified. It makes it possible to separate the initiation and propagation phases, thus feeding the discussions on the phenomena of priming in the presence of defects. In addition, some fatigue criteria are also discussed and the Defect Stress Gradient (DSG) approach is adapted to the studied material, by taking into account the size of the crystallographic grains. In the specific case of specimens with as-built useful sections, the role of the process of suppression of the building supports on the initiation of fatigue cracks is studied; the definition of the concept of defect size in the presence of roughness, at the scale of the surface undulation, is discussed. Knowing that initiation can occurs on a surface undulation or on an isolated defect (porosity or lack-of-fusion), an experimental method is proposed to analyze the competition between these factors. In a context of industrial development, the influence on the fatigue limit of the process parameters, related to the laser (scanning speed, power and hatching distance), or powder bed (chemical composition, particle size, bed thickness) is studied, in order to feed the discussions towards the process optimization regarding the fatigue strength
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Li, Kai. "Origins and evolution of near-surface microstructures and their influence on the optical property of AA3104 aluminium alloy." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/origins-and-evolution-of-nearsurface-microstructures-and-their-influence-on-the-optical-property-of-aa3104-aluminium-alloy(69670a59-c416-40a1-920f-a246959791a4).html.
Повний текст джерелаАнотація:
The microstructures of the near-surface layers on AA3104 aluminium alloys and their evolution through rolling and deep drawing processes have been investigated. The effect of the near-surface layers on the optical property of AA3104 aluminium alloy has also been assessed. It was revealed that two types of near-surface deformed layers, both with different microstructures different from the underlying bulk alloy, were generated on the surface of AA3104 aluminium alloy during rolling. Both of them are characterized by ultrafine, equiaxed grains, with diameters <100 nm for type A near-surface deformed layer and <200 nm for type B near-surface deformed layer. A high population density of nano-sized, oxygen-rich particles is present along grain boundaries within type A deformed layer. But type B deformed layer is free of oxygen-rich particles. Type A deformed layer was generated through two mechanisms, i.e. geometric dynamic recrystallization and mechanical alloying. Rolling introduced plastic strain in the surface/near-surface region of aluminium sheet was of sufficient magnitude to cause geometric dynamic recrystallization and thus microstructure refinement. In addition, the incorporation of oxides into the near-surface region was also involved in the formation of type A deformed layer. However, the formation of type B deformed layer was only attributed to severe strain induced geometric dynamic recrystallization. Type A deformed layer was mainly formed at the early stages of hot rolling. The subsequent rolling and deep drawing reduced the thickness of type A deformed layer by distributing it over a larger surface area. During cold rolling, type A deformed layer broke into patches with the extension of alloy surface. Type B deformed layer may be generated on the nascent surface if the strain is sufficiently severe to cause geometric dynamic recrystallization. For the hot rolled alloy sheets, the surface/near-surface region is mainly covered by type A deformed layer. However, for the alloys after cold rolling, only limited area is covered with type A deformed layer. The thicknesses of the near-surface deformed layers are not uniform across the surface of AA3104 aluminium alloy. The maximum thickness of type A deformed layer on transfer slab is approximately 4 µm, while that on re-roll gauge sheet is ~1 µm, and ~0.8 µm on the final gauge sheet, ~400 nm on formed cup and ~100 nm on formed can. Type A deformed layer is randomly distributed as patches on the cold rolled aluminium sheet. The reflectivity of oxygen-rich particles is lower compared with the reflectivity of aluminium. As a result, the type A deformed layer patches absorb more incident light than the area without type A deformed layer. Further, there are plenty of micro-scale mini-cracks present on type A deformed layer, their opening sizes are in the equivalent scale of the wavelength of visible light. The incident light may not able to be reflected out if they go into these mini-cracks. It is more prone to happen for short wavelength light since it is easier for them to go into the mini-cracks than long wavelength light. As a result, less short wavelength visible light is reflected from the type A deformed layer patches. Thus, such patches exhibit a yellow appearance while the surrounding area appears the original silver white aluminium appearance. The aluminium sheet with a high coverage of type A deformed layer exhibits a low total reflectance. Further, its total reflectance is with a significant “red shift”. Neither the macro-scale surface roughness nor the ultrafine grain size affects the total reflectance of aluminium alloys. The total reflectance of aluminium alloys is primarily dependent on the presence of type A deformed layer.
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Яременко, Денис Олегович. "Формування функціональних покриттів на сталі 40Х електроіскровим легуванням хромом та ніобієм". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/43127.
Повний текст джерелаАнотація:
Об’єкт дослідження – поверхневі шари сталі 40Х, отримані електроіскровим легуванням анодами хромом та ніобієм на повітрі.
Мета роботи – встановити вплив послідовності ЕІЛ хромом і ніобієм на мікроструктуру, фазовий склад і мікротвердість поверхневих шарів сталі 40Х.
Методи дослідження – гравіметричний, мікроструктурний, мікродюрометричний та рентгенофазовий. Показана можливість формування зміцнених покриттів (мікротвердістю 9,5 ГПа – 14,5 ГПа і товщиною 20 мкм – 35 мкм) електроіскровим легуванням Cr та Nb сталі 40Х при різній послідовності нанесення матеріалів анодів.
Встановлено вплив нанесення хрому та ніобію під час електроіскрового легування сталі 40Х на поверхневу мікротвердість, фазовий склад та мікроструктуру модифікованого шару.
Виявлено, що найбільшу мікротвердість (14,5 ГПа) має легований шар після ЕІЛ сталі Nb, а найбільшу товщину (35 мкм) – при пошаровому ЕІЛ у послідовності Cr- Nb.
Практичне значення: одержані в роботі результати та з’ясовані закономірності формування структури та характеристик модифікованих шарів під час електроіскрового легування можуть бути застосовані для подовження строку експлуатації деталей машин та механізмів.The object of the study is the surface layers of 40X steel, obtained by electrospark doping with chromium and niobium anodes in air. The aim of the work is to establish the influence of EIL chromium and niobium sequences on the microstructure, phase composition and microhardness of 40X steel surface layers. Research methods - gravimetric, microstructural, microdyurometric and X-ray phase. The possibility of forming reinforced coatings (microhardness 9.5 GPa – 14.5 GPa and thickness 20 μm – 35 μm) by electrospark alloying of Cr and Nb steel 40X with different sequence of anode materials application is shown. The influence of chromium and niobium deposition during electrospark alloying of 40X steel on the surface microhardness, phase composition and microstructure of the modified layer was established. It was found that the alloyed layer has the highest microhardness (14.5 GPa) after the EIL of Nb steel, and the greatest thickness (35 μm) - with layered EIL in the Cr-Nb sequence. Practical significance: the results obtained in the work and the regularities of the formation of the structure and characteristics of the modified layers during electrospark alloying can be used to extend the service life of machine parts and mechanisms.
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Kumar, Pawan. "Studies of wire-matrix interaction in some tungsten wire reinforced stainless steels." Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8980.
Повний текст джерелаАнотація:
There is potential for improving creep properties of stainless steels by reinforcing them with tungsten (W) wires. Past studies have shown that a detrimental factor that impairs the mechanical properties of tungsten wire reinforced superalloy composites is the formation of brittle intermetallic phases due to the interaction between W wire and constituents of the alloy matrices. Formation and growth of the intermetallic phases strongly depends on the matrix chemistry and for the retention of creep strength, matrix compositions that do not form intermetallic phases with tungsten are desirable for fabricating W wire reinforced composites for high temperature applications.
This research investigated the formation and growth of reaction phases in W wire reinforced 316L (W/316L) stainless steel and HP alloy steel (W/HP) that were fabricated by casting method. Additionally, the effect of composition on the evolution and kinetics of reaction phases was studied in some W wire reinforced experimental alloys based on Fe-Ni-Cr only (W/Fe-Ni-Cr). The fabricated composites were diffusion annealed in the temperature range 1000-1200°C for 25-500 hours. Microstructure and chemistry of the reaction phases in the as-cast and diffusion annealed composites were studied using scanning electron microscopy, energy dispersive spectroscopy and electron backscattered diffraction techniques. Growth kinetics of the reaction layers and average effective interdiffusion coefficients in the layers were determined for the composites.
Results showed that an intermetallic phase isostructural with µ-phase formed in the as-cast W/316L and W/Fe-Ni-Cr composites with 1 and 2 Fe:Ni matrix ratios. In W/HP a phase M12C with crystal structure similar to η-carbide was formed. These phases developed and formed brittle reaction layers around the W wires during diffusion annealing. A parabolic relationship between the µ-phase and η-carbide growth and diffusion annealing time indicated that the growth of reaction layers was diffusion controlled. In the W/Fe-Ni-Cr composites, formation of intermetallic phases did not occur in the matrices with 0.5Fe:Ni ratio, instead some isolated tungsten particles were observed in the matrix adjacent to the wires after diffusion annealing. In W/Fe-Ni-Cr composites with 1 and 2 Fe:Ni matrix ratio, the growth of µ-phase reaction layers during annealing was observed to be dependent on the matrix composition. It was found that with an increase in the Ni content in the matrix, growth of µ-phase reaction layer decreased.
The study presented in this thesis gives first-hand information on phase formation and growth kinetics of the reaction layers in W/316L and W/HP composites. It revealed that the interaction of W with 316L and HP alloy matrices leads to formation of cracked intermetallic and carbide reaction layers which are not desirable in the composites designed for high temperature applications. It has also been shown in this study that in W/Fe-Ni-Cr composites, intermetallic phase formation can be suppressed by increasing Ni content in the matrix. In the composite with high Ni contents in the matrix (0.5Fe:Ni ratio) intermetallic phases do not form even after diffusion annealing at 1200°C. This intermetallic free W/Fe-Ni-Cr composite can further be studied for its creep strength.
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Jagtap, Rohit. "The Effects of Ultrasonic Nano-crystal Surface Modification on Residual Stress, Microstructure and Fatigue Behavior of Low-Modulus Ti-35Nb-7Zr-5Ta-0.3O Alloy." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823317088871.
Повний текст джерела
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Seong, Jinwook. "Inhibition of Corrosion and Stress Corrosion Cracking of Sensitized AA5083." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429701294.
Повний текст джерела
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Lindsay, John Christopher. "Stress corrosion cracking and internal oxidation of alloy 600 in high temperature hydrogenated steam and water." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/stress-corrosion-cracking-and-internal-oxidation-of-alloy-600-in-high-temperature-hydrogenated-steam-and-water(1d6b037c-baf1-4397-a6c9-43835e7bb39a).html.
Повний текст джерелаАнотація:
In this study, the possibility of using low pressure hydrogenated steam to simulate primary water reactor conditions is examined. The oxides formed on Alloy 600 (WF675) between 350 Celsius and 500 Celsius in low pressure hydrogenated steam (with a ratio of oxygen at the Ni/NiO to oxygen in the system of 20) have been characterised using analytical electron microscopy (AEM) and compared to oxide that formed in a high pressure water in a autoclave at 350 Celsius with 30 cc/kg of hydrogen. Preferential oxidation of grain boundaries and bulk internal oxidation were observed on samples prepared by oxide polishing suspension (OPS). Conversely, samples mechanically ground to 600 grit produced a continuous, protective oxide film which suppressed the preferential and internal oxidation. The surface preparation changed the form of the oxides in both steam and autoclave tests. The preferential oxidation rate has been determined to be K_{oxide} = Aexp{-Q/RT}with A = 2.27×10^(−3) m^(2)s^(−1) and Q = 221 kJ.mol^(−1) (activation energy) for WF675 and A = 5.04 × 10^(−7) m^(2)s^(−1) and Q = 171 kJ.mol^(−1) for 15% cold worked WF675. These values are consistent with the activation energy of primary water stress corrosion cracking (PWSCC) initiation. Bulk oxygen diffusivities were calculated from the internal oxidation after 500 h exposures. At 500 Celsius the oxygen diffusivity was determined to be 1.79×10^(−20) m^(2)s^(−1) for WF675 and 1.21×10^(−20) m^(2)s^(−1) for 15% cold worked WF675, the oxygen diffusivity at 400 Celsius in 15% cold worked WF675 was calculated to be 1.49×10^(−22) m^(2)s^(−1).The Cr-depletion associated with preferential oxidation has been assessed by AEM. The Cr-depletion was asymmetric and it could not be accounted for by local variations in the diffusion rate. Chemically induced grain boundary migration is suggested as a possible explanation. Constant load SCC tests conducted in hydrogenated steam at 400 Celsius have shown a similar trend to the classical dependency of PWSCC as a function of potential. The SCC samples were also prepared with two surface finishes, OPS and 600 grit. In all SCC tests, significantly more cracking was observed on the OPS surface and all failures initiated from this surface.
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Riegler, Andreas [Verfasser], and Laurens Wigbolt [Akademischer Betreuer] Molenkamp. "Ferromagnetic resonance study of the Half-Heusler alloy NiMnSb : The benefit of using NiMnSb as a ferromagnetic layer in pseudo-spin-valve based spin-torque oscillators / Andreas Riegler. Betreuer: Laurens Wigbolt Molenkamp." Würzburg : Universitätsbibliothek der Universität Würzburg, 2011. http://d-nb.info/101816328X/34.
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Ayturk, Mahmut Engin. "Synthesis, annealing strategies and in-situ characterization of thermally stable composite thin Pd/Ag alloy membranes for hydrogen separation." Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-042307-012951/.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--Worcester Polytechnic Institute.Keywords: composite Pd and Pd/Ag membranes, alloying, Pd/Ag barrier, intermetallic diffusion, bi-metal multi-layer BMML deposition, electroless plating kinetics, high temperature x-ray diffraction, aluminum hydroxide surface grading, porous sintered metal supports, hydrogen separation. Includes bibliographical references (leaves 279-296 ).
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Sababi, Majid. "Nanocomposite films for corrosion protection." Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-132240.
Повний текст джерелаАнотація:
This thesis describes technical and scientific aspects of new types of composite films/coatings for corrosion protection of carbon steel, composite films with nanometer thickness consisting of mussel adhesive protein (Mefp‐1) and ceria nanoparticles, and polymeric composite coatings with micrometre thickness consisting of conducting polymer and ceria nanoparticles in a UV‐curing polyester acrylate (PEA) resin. The influence of microstructure on corrosion behaviour was studied for a Fe‐Cr‐V‐N alloy containing micro‐sized nitrides with different chemical composition spread in martensitic alloy matrix. The Volta potential mapping suggested higher relative nobility for the nitride particles than the alloy matrix, and the nitrides with higher amounts of nitrogen and vanadium exhibited higher nobility. Potentiodynamic polarization measurements in a 0.1 M NaCl solution at neutral pH and ambient temperature showed passivity breakdown with initiation of localized corrosion which started in the boundary region surrounding the nitride particles, especially the ones enriched in Cr and Mo. Mefp‐1/ceria nanocomposite films were formed on silica and metal substrates by layer‐by‐layer immersion deposition. The film formation process was studied in situ using a Quartz Crystal Microbalance with Dissipation (QCM‐D). The film grows linearly with increasing number of immersions. Increasing Mefp‐1 concentration or using Mefp‐1 with larger size leads to more Mefp‐1 being deposited. Peak Force Quantitative Nanomechanical Mapping (Peak Force QNM) of the composite films in air indicated that the elastic modulus of the film increased when the film deposited had a higher Mefp‐1 concentration. It was also noted that the nature of the outermost layer can affect bulk morphology and surface mechanical properties of the film. The QCM‐D study of Mefp‐1 on an iron substrate showed that Mefp‐1 adsorbs at a high rate and changes its conformation with increasing adsorption time. The QCM‐D and in situ Peak Force QNM measurements showed that the addition of Fe3+ ions causes a transition in the single Mefp‐1 layer from an extended and soft layer to a denser and stiffer layer. In situ ATR‐FTIR and Confocal Raman Microscopy (CRM) analyses revealed complex formation between Fe3+ and catechol groups in Mefp‐1. Moreover, optical microscopy, SEM and AFM characterization of the Mefp‐1/ceria composite film formed on carbon steel showed micron‐size aggregates rich in Mefp‐1 and ceria, and a nanostructure of well dispersed ceria particles in the film. The CRM analysis confirmed the presence of Mefp‐1/Fe complexes in the film. Electrochemical impedance microscopy and potentiodynamic polarization measurements showed that the Mefp‐1/ceria composite film can provide corrosion protection for carbon steel, and that the protection efficiency increases with exposure time. Composite coatings of 10 μm thickness composed of a UV‐curing PEA resin and a small amount of conductive polymer and ceria nanoparticles were coated on carbon steel. The conductive polymer (PAni) was synthesized with phosphoric acid (PA) as the dopant by chemical oxidative polymerization. The ATR‐FTIR and SEM analyses confirmed that the added particles were well dispersed in the coatings. Electrochemical measurements during long exposure in 0.1 M NaCl solution, including open circuit potential (OCP) and EIS, were performed to investigate the protective performance of the coatings. The results showed that adding ceria nanoparticles can improve the barrier properties of the coating, and adding PAni‐PA can lead to active protection of the coating. Adding PAni‐PA and ceria nanoparticles simultaneously in the coating can improve the protection and stability of the composite coating, providing excellent corrosion protection for carbon steel.QC 20131024
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Sexton, Cornelius Leo. "Rapid Alloy Scanning by laser cladding." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320605.
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Cao, Pengcheng. "Characterization of Laser Deposited Alloy 718." Thesis, KTH, Materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-182603.
Повний текст джерелаАнотація:
Additive Manufacturing (AM) is a method of producing three-dimensional objects using additive processes. It allows great flexibility in the processes and reduces the design-to-production time. Laser Metal Deposition (LMD) is one of AM methods under development and is based on the deposition technology. LMD has advantages in grain growth control, material functional grading, lower material storage requirement and more spatial freedom. Considering the outstanding features, it is important to study the characteristics of LMD products, which in this study is Alloy 718 for aerospace applications. Single-wall Laser LMD samples are built with varied process parameters using gas-atomized Alloy 718 powders. Two experiments were carried out with focuses on 1) evaluations and comparisons of the microstructural characteristics, porosity and hardness of the samples are performed; 2) The effect of heat treatments including solution treatment and aging on the microstructure as well as the hardness. The results of the experiments revealed directional solidification features and typical phases such as γ matrix, Laves phase and carbide. 0.06% average porosity and a majority of < 20 µm size are measured from the LMD samples. Only spherical gaseous pores are found while no lack-of-fusion pore is found. A hardness Vickers of 246 in average hardness is measured from the LMD samples. In the heat treated samples, δ phases were found; By direct-aging at 750 ℃ for 10 to 15 hours, the samples reach a maximum hardness of around 382 HV. The same hardness was reached by 1 hour of solution treatment at 950 ℃ followed by 5 hours aging at 750 ℃. The effects of processing parameters on the characteristics of LMD processed Alloy 718 are compared and discussed. A 2-dimentional map of porosity distribution along the length of the sample is made and the patterns are investigated along both the length and the height of the sample. It is found in the sample that the starting part of the deposit is higher in number of pores while the finishing part is larger in pore size. It is also found that the top layer of the deposit has the highest porosity level, pore number and pore size. Moreover, the hardness gradient along the build-up direction is evaluated and discussed. No significant hardness gradient was found. The precipitation hardening effect of LMD process and possible improvements are also discussed.
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Thomas, Jonova. "Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium Chromium Alloys." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849610/.
Повний текст джерелаАнотація:
A compositionally graded Ti-xCr (10≤x≤30 wt%) alloy has been fabricated using Laser Engineered Net Shaping (LENSTM) to study the microstructural phase evolution along a compositional gradient in both as-deposited and heat treated conditions (1000°C followed by furnace cooling or air cooling). The alloys were characterized by SEM BSE imaging, XRD, EBSD, TEM and micro-hardness measurements to determine processing-structure-property relations. For the as-deposited alloy, α-Ti, β-Ti, and TiCr2 (C15 Laves) phases exist in varying phase fractions, which were influential in determining hardness values. With the furnace cooled alloy, there was more homogeneous nucleation of α phase throughout the sample with a larger phase fraction of TiCr2 resulting in increased hardness values. When compared to the air cooled alloy, there was absence of wide scale nucleation of α phase and formation of ω phase within the β phase due to the quicker cooling from elevated temperature. At lower concentrations of Cr, the kinetics resulted in a diffusionless phase transformation of ω phase with increased hardness and a lower phase fraction of TiCr2. In contrast at higher Cr concentrations, α phase separation reaction occurs where the β phase is spinodally decomposed to Cr solute-lean β1 and solute-rich β2 resulting in reduced hardness.
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HUMBERT, PIERRE. "Etude de divers oxydes et interpretation des transitions auger de l'oxygene : caracterisation de couches oxydees de surface." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13205.
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Liang, Jing. "Direct laser fabrication of titanium alloy powders." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422998.
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Ejaz, Muhammad. "Metal dusting of laser-treated alloy 800H." Thesis, University of Manchester, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500503.
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Fathi, Shida. "Kontroll av zinkskikt på monterat räckesmaterial." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147182.
Повний текст джерелаАнотація:
Kontroll av zinkskikt på monterat räckesmaterial som görs ute i fält saknar en fastställd metod. Zinktjockleken har ett minimum tjocklekskrav enligt den svenska standarden ISO 1461:2009, som bestäms av dimensionen på ståldetaljens tjocklek. Trafikverket begär att med hjälp av detta examensarbete kunna begränsa antal mätningar på plats, då kan det ta allt för mycket tid och arbetsresurser i fall det skulle behövas kontroll av väg-och bro räckesanläggningar från beställaren. Sannolikhetsläran och stickprov i statistik hjälper oss att begränsa antalet mätningarna på skyddsanordningarna som görs ute i fält. Med hjälp av normalfördelning kommer man fram till den efter strävade metoden, som med en rimlig arbetsinsats ger en rättvisbild av skikttjockleken på monterat räckesmaterial. Vid variation av varmförzinkaren på vägräckesanläggningar undersöker man varje leverantörs räckesdel för sig, alltså man mäter zinktjockleken på en varmförzikare för sig, kontrollerar zinkskiktstjockleken på de och tar slutsatser sedan går man vidare till nästa tillverkare. Om vägräckena är mindre än 30 stycken mäter man zinktjockleken på respektive anläggning. För beräkning av zinkskiktstjockleken på monterad räckesmaterial börjar man med 30 mätningar och användning av den centrala gränsvärde satsen för att approximera till normalfördelning och analysera resultatet. Det slutliga resultatet av examensarbetet är ett Excelprogram med inmatade formler. Excel programmet är ett hjälpmedel för framtagning av 95 % konfidensintervall. Med hjälp av detta intervall kan man ta slutsatser om zinkskiktet på vägräckena uppfyller kravet eller inte och kunna komma fram till ett resultat. Om kravet ligger i intervallet eller store än intervallet är materialet godkänt.Control of zinc coating on assembled railing materials made on site lacks a common methodology. Zinc coating should have a minimum thickness requirements according to the Swedish standard ISO 1461:2009, which is determined by the dimension of the steel thickness. Trafikverket expects that with help from this thesis it could limit the number of measurements on site, otherwise it will take too much time and labor resources, in case control of road and bridge railing systems are required from the customer. Probabilities and sampling in statistics helps us to limit the number of measurements of the protective devices that are made in the field. Using normal distribution, one arrive at the element of method that with reasonable effort gives a fair picture of the layer thickness of the assembled railing materials. Upon variation of the galvanizers on road barrier systems, each part is investigated separately by measuring zinc thickness of a galvanizers, checking the zinc coating thickness on them, take conclusions and later on investigate the next manufacturer. If a crash barrier is less than 30 pieces, the zinc coating thickness is measured at each facility by itself. For calculation of the zinc coating thickness on a mounted railing material one begins with 30 measurements and the use of the central limit theorem to approximate it to normal distribution and analyze the results. The final result of the thesis is an Excel program with input formulas. The Excel program is a tool for producing 95% confidence interval. Using this interval, one can make conclusions that if the zinc coating on a crash barrier fulfills the requirement or not and later on be able to come up with a result. If the requirement is in the interval or larger than the interval, the material is approved.
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Merritt, Travis Robert. "Optoperforation of Intact Plant Cells, Spectral Characterization of Alloy Disorder in InAsP Alloy Disorder in InAsP Alloys, and Bimetallic Concentric Surfaces for Metal-Enhanced Fluorescence in Upconverting Nanocrystals." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25148.
Повний текст джерелаАнотація:
The techniques of optoperforation, spectral characterization of alloy disorder, and metal-enhanced fluorescence were applied to previously unconsidered or disregarded systems in order to demonstrate that such applications are both feasible and consequential. These applications were the subject of three disparate works and, as such, are independently discussed.
Despite being ostensibly restricted to mammalian cells, optoperforation was demonstrated in intact plant cells by means of successful femtosecond-laser-mediated infiltration of a membrane impermeable dextran-conjugated dye into cells of vital Arabidopsis seedling stems. By monitoring the rate of dye uptake, and the reaction of both CFP-expressing vacuoles and nanocellulose substrates, the intensity and exposure time of the perforating laser were adjusted to values that both preserved cell vitality and permitted the laser-assisted uptake of the fluorophore. By using these calibrated laser parameters, dye was injected and later observed in targeted cells after 72 hours, all without deleteriously affecting the vital functions of those cells.
In the context of alloy disorder, photoluminescence of excitonic transitions in two InAsxP1-x alloys were studied through temperature and magnetic field strength dependencies, as well as compositionally-dependent time-resolved behavior. The spectral shape, behavior of the linewidths at high magnetic fields, and the divergence of the peak positions from band gap behavior at low temperatures indicated that alloy disorder exists in the x=0.40 composition while showing no considerable presence in the x=0.13 composition. The time-resolved photoluminescence spectrum for both compositions feature a fast and slow decay, with the slow decay lifetime in x=0.40 being longer than that of x=0.13, which may be due to carrier migration between localized exciton states in x=0.40.
In order to achieve broadband metal-enhanced fluorescence in upconverting NaYF4:Yb,Er nanocrystals, two nanocomposite architectures were proposed that retrofit metallic nanoshells to these lanthanide-doped nanocrystals. The typical monometallic construction was rejected in favor of architectures featuring Au-Ag bimetallic concentric surfaces, a decision supported by the considerable overlap of the calculated plasmon modes of the metallic structures with the emission and absorption spectrum of the nanocrystals. Furthermore, precursors of these nanocomposites were synthesized and photoluminescence measurements were carried out, ultimately verifying that these precursors produce the requisite upconversion emissions.Ph. D.
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Lee, Caroline Sunyong. "Surface layer formation on Pb/Sn alloys." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11603.
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Soib, Bin Selamat Mohmad. "Laser surface processing of Ti-6Al-4V alloy." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366777.
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Olakanmi, Eyitayo Olatunde. "Direct selective laser sintering of aluminium alloy powders." Thesis, University of Leeds, 2008. http://etheses.whiterose.ac.uk/1476/.
Повний текст джерелаАнотація:
The SLS/SLM of aluminium powder had been investigated by studying the effect of powder properties and laser processing parameters on the microstructures and properties of both single layer and multiple layer builds. On the basis of experimental evidence, the SLS/SLM of aluminium powders could be categorised into full melting (SLM) which was found to have occurred in both pure and pre-alloyed aluminium powders, and binary liquid phase sintering (SLS) which occurred in blended bimodal or trimodal powders. That successful disruption of the oxide film is possible is a significant result, as is the constitutional effect on this. The spheroidisation and oxide disruption phenomena in SLS/SLM processed aluminium powders arc suggested to be mainly controlled by the amount of oxide on the as-received powder's surface, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles as well as the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film (alumina, mullite, and spinel). It was discovered that the attainment of high sintered density and desirable microstructural properties in the blended aluminium powders is consequent upon the determination of the right processing conditions, appropriate choice of powders (in terms of particle size distribution, spherical particle shape, and component ratio). Moreover, it is now evident that chemical constitution of the blended aluminium powders only becomes influential in the determination of the properties of SLS processed parts when the choice of processing parameters and powder properties are correct. The choice of powder properties determines the thermal conductivity of the powder bed which in effect controls the sintered properties. This had been inferred from the relationship between powder tapping density on one hand, and selective laser sintered (SLS) density, dendrite spacing and fraction of primary phase on the other hand. In making smaller samples, it has been shown that the attainment of high sintered density (up to 90%) and a good microstructure are feasible. These arc accompanied by reasonable hardness values, comparable to those of cast Al-12wt%Si castings. In fabricating larger sized parts for mechanical testing, defects such as delamination became more noticeable leading to poor mechanical properties in those samples. Thus, it is now clear that physical limitations of the sintering machine hinder the production of SLS/SLM processed parts having excellent structural integrity. On the basis of this work, it is envisaged that the use of pre-alloyed Al-Si powders of uniform composition, but a wider particle size and size distribution, blended to optimise the bed density, offers the potential to produce light alloy components by SLS. In conclusion, the specific laser energy input, the component ratio, and the particle size and size distribution of the powder were found to have strongly influenced the densitication mechanism and the solidification process in a small sized aluminium powdered part fabricatedb y SLS/SLM process.
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Zhang, Tao. "Laser surface hardening of AISI 1518 alloy steel." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/723.
Повний текст джерелаАнотація:
The laser surface hardening process will enhance the hardness profile of automotive components and ensure better process control and predictability of quality as compared to the conventional hardening processes. A 2KW Nd-YAG laser system was used to harden the surface of alloy steel with various process parameters (laser power, focal spot diameter and beam velocity). The results (microhardness, microstructure change and residual stress distribution) were measured and analyzed with Vickers microhardness tester, optical/electron microscope and hole-drilling residual stress equipment. Statistical analyses of the experimental data were used for explaining the relationships between process parameters, microhardness and microstructure. General thermal hardening was applied in the research to show the influence of heating temperature and cooling method on microstructure and mechanical properties. Also, the results were compared with laser surface hardening process from microhardness, microstructure and residual stress to show the advantage of laser surface hardening. Through analysis of the results of the laser surface hardening experiments, a suitable laser power density and interaction time for optimum hardening was obtained. The presented laser surface hardening process can also be applied to other alloy steel surface hardening process.
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Laurent, Michel P. "A continuum surface layer effect in polycrystalline aggregates." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06082009-170819/.
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De, 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 джерелаАнотація:
L'étude des mécanismes de nitruration du composé intermétallique Sm2 (Fe, Co)1#7 est effectuée sur des échantillons massifs à l'aide de la diffraction des rayons X et de la microscopie électronique à balayage. Nous avons utilisé deux modes de nitruration (lit fluidisé et flux gazeux) afin de comparer les processus mis en jeu lors du traitement. Des comportements différents interviennent au niveau de la distribution de l'azote dans les échantillons, des cinétiques de nitruration globale et de la couche de surface. Il apparaît que la diffusion de l'azote est principalement volumique dans le cas de la nitruration en lit fluidisé alors que les micro-fissures présentes dans les échantillons tiennent lieu de chemins de rapide diffusion pour la nitruration sous flux gazeux. L'étude des mécanismes d'oxydation du composé intermétallique Sm2 (Fe, Co)1#7 est effectuée sur des échantillons massifs et des poudres à l'aide de la diffraction des rayons X, des microscopies optique et électronique à balayage et d'une microsonde électronique. Les échantillons massifs sont oxydés à l'air tandis que les poudres sont traitées sous oxygène pur. Nous avons observé la formation de trois couches d'oxydes successives, différentes par leur aspect et leur composition. La cinétique d'oxydation est déterminée à partir de la croissance des couches sur les échantillons massifs et des mécanismes d'oxydation sont envisagés. La cinétique d'oxydation des poudres est étudiée par thermogravimétrie sur des courbes isothermes. Une loi empirique de cinétique d'oxydation globale est utilisée pour ajuster les courbes expérimentales.
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Forsman, Tomas. "Laser welding of aluminium alloys /." Luleå, 2000. http://epubl.luth.se/1402-1544/2000/39/index.html.
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Yoon, Jong Won. "Laser welding of aluminium alloys." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343303.
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Henke, M., and G. Gerlach. "A multi-layered variable stiffness device based on smart form closure actuators." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35622.
Повний текст джерелаАнотація:
This contribution describes the properties and limitations of multi-layered mechanical devices with variable flexural stiffness. Such structures are supposed to be components of new smart, self-sensing and self-controlling composite materials for lightweight constructions. To enable a proper stiffness control, reliable actuators with high actuation capabilities based on smart materials are used. Those actuators are either driven by electroactive polymers (EAPs) or shape memory alloy (SMA) wires. They control the area moment of inertia of the multi-layered bending structures. To change the area moment of inertia and, hence, the flexural stiffness of an multi-layered beam within a wide range, it is necessary to stack as many layers as possible over each other. The fundamental function of this approach is demonstrated with a three-layer stack consisting of three independent layers and four form closure actuators driven by SMAs. This experimental set-up was able to change its bending stiffness k by a factor of 14.6, with a minimum and maximum stiffness of kmin = 0.11 N mm¯¹ and kmax = 1.73 N mm¯¹, respectively. The usage of four independently controllable actuators yields nine independent flexural-stiffness states of the beam. Both analytical and numerical calculations have shown good agreement with the measured stiffness values.
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Delaunay, François. "Etude de l'influence des éléments mineurs d'addition sur l'oxydation à haute température d'alliages base nickel." Rouen, 1997. http://www.theses.fr/1997ROUES029.
Повний текст джерелаАнотація:
La compréhension des phénomènes d'oxydation à haute température des alliages base nickel revêt un intérêt particulier pour l'industrie nucléaire. Les performances de ces alliages, tout comme celles des aciers, sont fortement influencées par les différents éléments mineurs d'addition. Six alliages commerciaux ont été traités entre 800°C et 1000°C sous air et étudiés à l'aide des méthodes d'analyse complémentaires suivantes : spectroscopie de photoélectrons induits par un rayonnement X, spectroscopie infrarouge à transformée de Fourier, diffraction des rayons X et microscopie électronique à balayage couplée avec un système d'analyse en énergie des rayons X émis. Les résultats obtenus mettent en évidence le rôle très important des éléments mineurs d'addition que sont le manganèse, le silicium, le titane, l'aluminium et le niobium sur les mécanismes d'oxydation. La diffusion rapide du manganèse et du titane à travers la phase rhomboédrique formée initialement, conduit à la formation d'une couche d'oxydes de structure duplex. L'oxydation intergranulaire du titane et de l'aluminium est substantielle et peut être corrélée avec l'épaisseur de la zone affectée par la déplétion en chrome dans l'alliage sous-jacent. Le silicium favorise la formation du chromite de manganèse, cependant, le développement d'une couche continue de silice à l'interface oxyde-alliage ralentit la cinétique d'oxydation. La présence de niobium semble également avoir un effet bénéfique sur la résistance à l'oxydation. La comparaison de ces résultats avec ceux obtenus sur des aciers ferritiques et austénitiques étudiés au laboratoire et avec ceux issus de la littérature permet d'apporter des informations qualitatives concernant la vitesse de diffusion des différents éléments en fonction de la matrice. Ainsi, dans les aciers ferritiques, ou les vitesses de diffusion sont plus élevées que dans les matrices austénitiques, la diffusion du titane est plus rapide que celle du manganèse. Dans les aciers austénitiques, ces deux éléments diffusent à des vitesses comparables alors que dans les alliages base nickel, le manganèse diffuse plus vite que le titane.
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Власенко, Олександр Володимирович, Александр Владимирович Власенко та Oleksandr Volodymyrovych Vlasenko. "Електрофізичні та магніторезистивні властивості плівкових сплавів на основі Fe і Ge". Thesis, Сумський державний університет, 2021. https://essuir.sumdu.edu.ua/handle/123456789/85451.
Повний текст джерелаАнотація:
Дисертаційна робота присвячена дослідженню електрофізичних, магніторезистивних, магнітооптичних властивостей та ефекту Холла в плівкових системах на основі металу (Fe) і напівпровідника (Ge) в умовах фазоутворення. У плівкових сплавах, сформованих на основі відпалених до 900−1070 К тришарових плівок Fe(5−10 нм)/Ge(2−25 нм)/Fe(15−50 нм), в залежності від співвідношення концентрацій атомів окремих компонент утворюються магнітні плівки германідів заліза Fe2Ge, FeGe і FeGe2 із середніми розмірами кристалітів 15–30 нм. Порівняння експериментальних величин питомого опору двошарових плівкових систем Ge/Fe/П із розрахунковими на основі моделі, в якій зберігається індивідуальність окремих шарів, свідчать про те, що відміну між цими величинами можна пояснити ефектом утворення екситонів Ваньє−Мотта на основі 4 % електронів провідності. Перехід плівки германіду заліза із аморфного стану в кристалічний відбувається при температурах Та→к = 560−590 К в залежності від товщини плівки. Формування термостабільних (ТКО ~ 10−4 К−1) фаз FeGe і FeGe2 по всьому об’єму зразка приводить до зростання величини МО від 0,02–0,04% у невідпалених системах до 0,30–0,44 % у відпалених до 900 К зразках. Установлено, що у системах на основі плівок Fe і Ge, спостерігається залежність кута Керра від індукції магнітного поля у вигляді прямокутної петлі гістерезису, що свідчить про реалізацію двох магнітних станів і швидкодію чутливих елементів приладів у магнітному полі. Експериментально встановлено, що величина сталої Холла для двошарових плівок на основі Fe і Ge (6–11)·10−9 м3/Кл при зростанні індукції магнітного поля від 0 мТл до 100 мТл. При збільшенні інтервалу термообробки плівкових зразків до 570 К стала Холла зменшується від 11·10−9 м3/Кл до 6·10−9 м3/Кл. Досліджені властивості тонких плівок нітриду вуглецю як захисних покриттів для плівкових чутливих елементів на основі германідів металів.Диссертация посвящена исследованию электрофизических, магниторезистивных, магнитооптических свойств и эффекта Холла в пленочных системах на основе металла (Fe) и полупроводника (Ge) при фазообразовании. Изучение прoцесов фазообразования в двухкомпонентных пленочных материалах на основе Fe и Ge, сформированных методом послойной конденсации с последующей термообработкой в интервале температур 300–1070 К, позволили устаовить, что в пленочных сплавах, сформированных на основе отожжённых до 900–1070 К трехслойных пленок Fe (5–10 нм)/Ge (2–25 нм)/Fe (15–50 нм), в зависимости от соотношения концентраций атомов отдельных компонент образуются магнитные пленки германидов железа Fe2Ge, FeGe и FeGe2 со средними размерами кристаллитов 15–30 нм. Сравнение экспериментальных величин удельного сопротивления двухслойных плёночных систем Ge/Fe/П с расчетными на основе модели, в которой сохраняется индивидуальность отдельных слоёв, свидетельствует о том, что отличие между этими величинами можно объяснить эффектом образования экситонов Ванье–Мотта на основе 4 % электронов проводимости. Переход пленки германида железа из аморфного состояния в кристаллическое происходит при температурах Та→к = 560–590 К в зависимости от толщины образца. Формирования термостабильных (ТКС ~ 10–4 К–1) фаз FeGe и FeGe2 по всему объему образца приводит к росту величины МО от 0,02–0,04 % в неотожжённых системах до 0,30–0,44 % в отожженных до 900 К образцах. Наблюдается зависимость угла Керра от индукции магнитного поля в виде прямоугольной петли гистерезиса, что свидетельствует о реализации двух магнитных состояний и быстродействии чувствительных элементов устройств в магнитном поле. Получено, что постоянная Холла для двухслойных пленок на основе Fe и Ge имеет величину (6–11) .10-9 м3/Кл при росте индукции магнитного поля от 0 до 100 мТл. При увеличении интервала термообработки пленочных образцов до 570 К постоянная Холла уменьшается от 11·10−9 м3/Кл до 6·10−9 м3/Кл. Исследованы свойства тонких пленок углерода и нитрида углерода как защитных покрытий для пленочных чувствительных элементов. Показано, что плотность пленки CNx/Si (100) уменьшается при снижении температуры подложки и увеличении толщины образца, а максимальная концентрация атомов алмазоподобной структуры наблюдается в области подложки, а при толщине d ≥ 2 нм. Пленка однородная с постоянной плотностью, что свидетельствует о соответствии пленок CNx требованиям к покрытиям, которые могут быть использованы как защитные термостойкие слои для чувствительных элементов сенсорной электроники на основе силицидов и германидов металлов.
The thesis is devoted to systematic research of electrophysical, magnetoresistive, magneto – optical galvanomagnetic properties of film systems on the basis of metal (Fe) and semiconductor (Ge) in the conditions of phase formation. In film alloys formed based on annealed to 900–1070 K three-layer films Fe(5–10 nm)/Ge(2–25 nm)/Fe(15–50 nm), depending on the ratio of the concentrations of atoms of individual components, magnetic films are formed iron germanides Fe2Ge, FeGe and FeGe2 with average crystallite sizes of 15–30 nm. Comparison of resistivity of two-layer Ge/Fe/S (S-substrate) film systems with calculated ones based on the model, which preserves the individuality of individual layers, indicates that the difference between these values can be explained by the effect of Vanier-Mott excitons based on 4 % conduction electrons. The transition of the iron germanide film from the amorphous state to the crystalline state occurs at temperatures Tа→c = 560–590 K depending on the film thickness. The formation of thermostable (TRC ~ 10–4 K–1) phases of FeGe and FeGe2 over the entire volume of the sample leads to an increase in the value of MR from 0.02–0.04 % in non-annealed systems to 0.30–0.44 % in annealed to 900 K samples. It is established that in systems based on Fe and Ge films, the dependence of the angle Θ on the induction of the magnetic field in the form of a "stepped hysteresis loop" is observed, which indicates the realization of two magnetic states and the speed of sensitive elements of functional devices in a magnetic field. It has been experimentally established that the value of the Hall constant for two-layer films based on Fe and Ge (6–11)·10–9 m3/C with increasing magnetic field induction from 0 mT to 100 mT. When increasing the heat treatment interval of film samples to 570 K, the value of the Hall constant decreases from 11·10–9 m3/C to 6·10–9 m3/C. The properties of thin films of carbon and carbon nitride as protective coatings for film sensitive elements have been studied.
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Sharman, Robert John. "Direct laser fabrication of a burn resistant titanium alloy." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289751.
Повний текст джерела
35
Bransden, Antony Stuart. "Laser surface alloying of aluminium alloys." Thesis, Coventry University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241106.
Повний текст джерела
36
Okon, Panton. "Laser conduction welding of aluminium alloys." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400234.
Повний текст джерела
37
Calder, Neil J. "Laser welding of certain airframe alloys." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366402.
Повний текст джерела
38
Ebadan, Gracie E. "Laser welding of selected aerospace alloys." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/7114.
Повний текст джерелаАнотація:
The literature relating to the laser welding of a number of alloys was studied, this revealed gaps in the current state of knowledge. It was found that no indepth parametric or inicrostructural investigations had been carried out into the laser welding of non-ferrous alloys. Although problems associated with the laser welding of aluminium alloys had been identified, there was little in the literature to suggest an indepth study into the effect of surface modifications in enhancing the laser weldability of this material had been carried out. The laser welding of aluminium based metal matrix composites has also yet to be studied in detail. A programme was therefore set up to carry out an indepth investigation into the laser welding of a number of alloys namely; Nimonics C263, and PE11, aluminium 6061, and aluminium 6061 based boron fibre reinforced, and silicon carbide particulate reinforced metal matrix composites. The study was aimed at developing an understanding of the microstructural effects of the laser welding process on the alloys, and assessing the structural integrity of the resultant welds. The effect of laser processing parameters such as laser power, laser beam traverse speed, lens focal length, and the manipulation of these parameters on the welding efficiency and weld area integrity was also investigated. Other tasks within the project included a study on the possibility of using an anodic film to enhance the laser weldability of Al 6061. Finally attempts were made to identify novel phases observed in the weld area of the composite materials. Nimonics C263, and PEll exhibited laser welds free of cracks and porosity. The difference in composition between the two alloys did not result in any significant dissimilarities in their response to the laser welding process. The welds in both alloys exhibited a fine columnar dendritic microstructure, and while carbides were observed in the interdendritic regions of the welds, electron optical analysis did not reveal any y precipitates in this region. It was concluded that for the welding of thin gauge materials above a threshold laser power the resultant welding efficiency shows a greater dependence on laser beam mode, and laser spot size, than on laser power, and beam traverse speed. Aluminium 6061 was not easily welded with a laser in its as received form, and the welds showed some degree of porosity. Anodising was found to improve the welding efficiency in this material. While the presence of an anodic film on the metal surface increased the welding efficiency of the alloy, no relationship was found between the thickness of the anodic film and welding efficiency in the range of film thicknesses investigated in this work. Weld regions were observed to be cellular dendritic in structure, with narrow heat affected zones. No precipitates or low melting point phases could be identified in the weld region. Melt zones were successfully produced in the composite materials, with the main problem encountered being that of porosity adjacent to the weld bead. It was shown that manipulation of the laser welding parameters resulted in a decrease in this porosity. In the weld beads, a number of novel phases were observed. These were identified with the aid of TEM, and SIMS analysis techniques.
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Kuo, Je Ming, and 郭哲銘. "Investigating the Capping-layer effect on the PbAu alloy layer." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/69367197347650542123.
Повний текст джерелаАнотація:
碩士國立清華大學
先進光源科技學位學程
103
The previous research shows that that a binary alloy composed of heavy atoms, Pb and Au, has large Rashba effect, yielding two cones at Γ ̅ and two giant Rashba splitting at M ̅. Experiments and first-principles calculations of the electronic structure indicated that such a Rashba effect may be produced only via a special buckling configuration induced by squeezing from the top Au capping layers and bottom Pb films. In this research, we demonstrated that with Bi as the capping layer on PbAu alloy, the Rashba effect is reproduced as well. This result means that Rashba-splitting band structure of PbAu alloy layer is caused by a capping layer on the top, which breaks the inversion symmetry and enhances the buckling height. We tried to deposit Bi onto PbAu alloy layer at Room temperature and low temperature, T = -130 ˚C, respectively and found that Rashba-splitting band structure only showed up at room temperature. It means that the atoms of capping layer must be at specific locations that are commensurate with Au atoms of alloy. In addition, we found that the binding energy of Rashba-splitting band structure shifted into higher binding energy and dispersion changed, indicating that we can use different kinds of atoms as the capping layer to tune the Rashba effect of the middle alloy.
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CHEN, CHI-AN, and 陳麒安. "Nickel-phosphorus alloys deposited on magnesium alloy micro-arc oxidation layer using different catalysts." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/70561224320343144235.
Повний текст джерелаАнотація:
碩士國防大學理工學院
化學工程碩士班
105
Magnesium-lithium alloy(LZ91) is currently the lightest of practical metal, its advantages are light (similar to plastic), higher strength, specific rigidity and better heat dissipation. Magnesium alloy is extremely to corrosion which seriously affecting its application in real life. In this study, Micro - arc oxidation of wet - type method was used to prepare a oxide film on magnesium alloy which improves corrosion resistance. The surface of the magnesium-lithium alloy treated by micro-arc oxidation was not beautiful. In corrosive environment, the outside layer is prone to failure. In order to solve this problem, the outer layer of oxide film to seal, which can prevent corrosion factor invasion. The oxide layer is without any activity, which needs to soak in catalytic active solution, therefore nickel ions can be catalyzed and evenly coated on the micro-arc oxidation of magnesium alloy to enhance the corrosion resistance and aesthetics. First discussion different voltage on corrosion resistance of micro-arc oxidation layer. After finding the best operating conditions, and then explore the characteristics of different catalysts and the effect of coating on the best conditions of micro - arc oxidation. Finally, the micro-arc magnesium oxide alloy with different catalyst was coated with nickel-phosphorus layer by electroless plating, and observe the corrosion resistance. In the experiment, the surface morphology and cross-sectional were observed by scanning electron microscopy(SEM). Electrochemical test linear polarization curve and salt spray to detect the corrosion resistance. The size of the catalyst particles is analyzed by a light scattering instrument. Catalyst stability is analyzed by stability analysis instrument. Contact angle analysis instrument analyzes the affinity between the catalyst and the micro-arc oxidation layer. The experimental results show that: the flat and dense oxide layer was prepared at a Bipolar pulses voltage of 400 V, which corrosion resistance is better. In the corrosion resistance test, the electrochemical test obtained corrosion current of 1.4 × 10-7 A / cm2, salt spray test can be passed 48 hours. Next, with different catalyst on the best micro-arc oxidation layer. The results show that the pH value of the 7 N type catalyst has a better performance. Its effective particle size is the smallest, the stability is better. The affinity with the micro-arc oxide layer is best and the corrosion resistance to the micro-arc oxide layer is less affected. Subsequent to electroless nickel-phosphorus layer, which can pass salt spray 24 hours . It is the best process conditions.
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Chang, Chih-Wei, and 張智維. "A study of optical reflective layer with copper alloy." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/dqr7rs.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
製造科技研究所
93
In this study, copper alloy adding Ti-Zr and Al-Zr was the target and made the cupper alloy ingots by vacuum arc remelter (VAR). After rolling and heat treatment, the two-inch round target was cut by wire electrical discharge machining (WEDM). DC sputtering deposited cupper alloy thin films on silicon base materials and optical glasses to discuss the thin film microstructures、compositions、practical performances and optical characteristics. Metallographic methods and structure analysis were used to identify the reflectivity、surface morphology and structures of copper thin films. The results show that Cu-Ti-Zr alloy(CTZ1) thin films have 72% reflectivity with 650nm wave length. When more elements are added in copper alloys, the reflectivity and weatherability decrease. Higher Al element is good for corrosion resistance; Ti could restrain grain growth and enhance the heat resistance performance.
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Chen, Kuan-Ting, and 陳冠廷. "Hole Mobility Calculation of Strained Silicon-based Alloy Inversion Layer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/19191830524761977918.
Повний текст джерелаАнотація:
碩士國立中興大學
物理學系所
101
Advanced MOSFET device formed from novel Si-based materials, such as silicon-germanium (SiGe) alloys, are simple and low cost to manufacture. In this thesis we focus on hole mobility in the inversion layer of the MOSFETs using novel silicon-germanium alloy channel materials. The primary topic of this work is the theoretical calculation of hole mobility in the SiGe alloy PMOSFET inversion layer. Hole mobility in the SiGe alloy inversion layer is calculated using a k.p band structure method and the Kubo-Greenwood mobility formula. The model parameters used in the calculations are calibrated by matching the measured low-field mobility of Si and Ge. We study alloy-limited, phonon-limited, and total mobilities in the inversion layers of relaxed and biaxial strained SiGe on (100), (110), and (111) substrates, respectively.
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Parng, Shaw-Hwa, and 龐紹華. "Injection Molding of Plastic Parts Covered with Superplastic Alloy Layer." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/69428580277467378923.
Повний текст джерелаАнотація:
博士國立臺灣大學
機械工程學研究所
89
A hybrid process combining the forming of superplastic Zn-22Al sheet with plastic injection molding is developed in this study. The product is a plastic part covered with a zinc-aluminum layer, providing a continuous metal enclosure for shielding against EMI. The process is first investigated with aid of moldability study and process observation. Plates with features such as rib or boss are molded. The moldings of housing cases with different degrees of preforms for improving moldability and a variety of schemes for reducing warpage are also investigated. In the process observation with aid of short-shots, it is found that almost 80% of the sheet deformation for forming ribs occurs during the final filling stage. For defining moldability, melt temperature and injection pressure are found to be the most critical processing parameters after performing experiments with Taguchi method. The moldability is then defined based on the molding area on the plane of these two parameters. Increasing sheet thickness, decreasing the rib depth and decreasing the flow length enlarge the molding areas and improve moldability. The biggest effective strain and smallest residual thickness are found to be in the center of the boss. For successfully molding of Zn-22Al covered plastic housing case, an appropriate preform depth accompanied with proper melt filling channel is necessary for moldability. Excess preform depth of the Zn-22Al sheet would cause fracture of the sheet on the corners, and induce big pressure pulling down the sheet when melt flowing in the thick channel. For reducing warpage of molded plastic housing cases with Zn-22Al sheet, Zn-22Al sheet pre-rolled with ABS layer on the surface before injection molding is found to be effective in reducing warpage. With the total thickness of sheet-plastic composite fixed, the optimum thickness ratio for best bending rigidity and minimum weight are also derived in this study. The simulations of process are also carried out with finite element softwares of MOLDFLOW for melt filling and ABAQUS for sheet forming. The distributions of pressure and melt temperature on various sites are obtained from the simulated results using MOLDFLOW. These data is then used as loading conditions to simulate the deformation process of the Zn-22Al sheet using ABAQUS during melt filling of the cavity for plate with rib. The simulated sheet thickness distribution in the rib sections and strain rate during the filling process are compared with the measured data.
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Gu, Shao-Ming, and 谷紹民. "Synthesis of Large-Area Graphite Layer from Fe-Ni-Cu Alloy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/x369dh.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
材料科學與工程研究所
99
This research was using the liquid phase of Fe-Ni-Cu alloy to dissolve graphite powder; precipitate then synthesis to a large-area graphite layer on the surface of the alloy. The research used a sintering vacuum at 1350 ℃ for up to 5 hours. To observe the interaction of Fe-Ni-Cu with carbon at different isothermal times, using samples of 1.5C-Fe58.45Ni25.05Cu15 (wt%), lead to the investigation of the graphite layer growth mechanism. According to this research, copper had played an important role of controlling the segregation of carbon. The growth rate and nucleation had been elevated dramatically due to the existence of copper at a small amount. The content distribution range (carbon content 1.5 wt% to 2.5 wt%, and the copper content 1.0 wt% to 30 wt%) of carbon and copper could lead to the ideal result expected which is the large-area graphite layer. The outcome would be at its best quality at this specific allocation, which was carbon content 1.5 wt% and copper content at 15 wt%. We could find graphene signal through Raman analysis at 1.5 wt% carbon and 1 wt% copper. Due to the change of isothermal times, the mechanism of graphite layer growth could be deduced. The variation of growth steps could influence graphite layer’s wrinkle level and its appearance. Under this content of carbon and copper (1.5C-Fe58.45Ni25.05Cu15), which etched by nitric acid, could separate into a large-area graphite layer from Fe-Ni-Cu alloy. The graphite layer sample would be a beneficial usage to future development.
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CHENG, CHEN-YI, and 鄭駿毅. "The Study of Corrosion Properties of MAO Layer on Magnesium Alloy." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/02362332454877411327.
Повний текст джерелаАнотація:
碩士國防大學理工學院
化學工程碩士班
104
Magnesium and its alloys as the lightest structural material, has some excellent properties such as low density, high strength, excellent casting and workability, etc. The application of magnesium alloys has been widely used in industry field. However, magnesium alloys have a poor corrosion resistance and limit their application. Many surface treatment techniques have been developed to protect the magnesium alloys from corrosion, including chemical treatment, oxidation, organic coatings, conversion coating, anodizing and metal coating. In this study, magnesium alloy (AZ31) was used as a substrate, the MAO technique was used to produce an oxidation layer having a high corrosion resistance and to improve the corrosion resistance of magnesium alloy. In first, the effect of different waveforms (DC, unipolar pulses, bipolar pulse) and voltages on the corrosion resistance of AZ31 that prepared by MAO process and then coated a nickel phosphorus layer are studied. The surface morphology and the cross-sectional of coatings were analyzed by SEM, the phases analysis were carried out by XRD, the corrosion behavior of coatings were measured by electrochemical linear polarization curve test and salt spray test. Finally, the adhesion between nickel-phosphorus layer and MAO layer were measured by a pull adhesion test, to find out the relationship between the adhesion and corrosion resistance. The experimental results show that the main components of micro-arc oxidation layers prepared by different parameters included MgO, Mg2SiO4, MgF2 and Mg. The different operated parameters of MAO process played a dominate role on the corrosion resistance, pore size and porosity of MAO layer. When the bipolar pulse waveform voltage is at 400 V, the MAO film has the best corrosion resistance due to its maximum pore size and the lowest porosity, and the salt spray test can through 144 hours. Then, the MAO films was coated a nickel-phosphorus layer by chemical plating and the corrosion resistance of MAO-nickel-phosphorus layer was studied. The results show that the MAO films formed at a bipolar pulse waveform voltage of 400 V and coated nickel-phosphorus layer has the best corrosion resistance that can resist corrosion on salt spray test for 96 hours. Therefore, the optimal parameters on preparing a MAO film was the bipolar pulse waveform and the operated voltage was at 400 V; moreover, it can obtain best adhesion between MAO layer and nickel-phosphorus layer, and has the best corrosion resistance.
46
Fan, Chao-Hsiung, and 范朝雄. "Study on the Oxidation Wear Behavior of Laser Clad Layer of Pre-placed Nickel-based Alloy Powder." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/46056716634181532285.
Повний текст джерелаАнотація:
碩士國立中正大學
機械系
90
Abstract In this work, the Nickel-based alloy powder Metco 15E and Colmonoy 88 were mixed with binder and were pre-placed on the surface of mild steel substrate and then cladding of these alloy by using Nd-YAG laser was carried out. Study was carried out to evaluate the wear characteristics of clad layers before and after oxidation at elevated temperature. In order to probe into the characteristics of oxidation layer, compositions of oxides were analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray Spectrometry (EDS). Besides, the influence of the oxides on high temperature wear test results was also an important issue which was analyzed using EDS. Wear traces were investigated using SEM to identify the possible wear mechanisms. The results of the high temperature oxidation show that the oxide layer consists mainly of the Cr and Si oxides. The dilution of pre-placed laser clad layer with the substrate was higher than that achieved by synchronic powder feeding. It revealed severe oxidation on the pre-placed laser clad layer. High temperature wear test results show that the wear resistance of oxidized clad layer was superior to that of the as-clad layer. This result implies that oxidized layer is advantageous for high temperature wear resistance. Moreover, the wear resistance was inferior under lower wear speed. Surface analysis results shows that the dominant wear mechanisms were adhesive mechanism and detach mechanism. In general, the wear resistance of Colmonoy 88 was better than that of Metco 15E.
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Wu, CH, and 吳忠興. "Al2O3/ZrO2 Double Layer on Co-Cr-Mo Alloy by Electrolytic Deposition." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/45966088070308371001.
Повний текст джерелаАнотація:
碩士國立中興大學
材料工程學研究所
89
Double layers of Al2O3/ ZrO2 composite films were Co-Cr-Mo alloy in 0.003125M ZrO(NO3)2 and then in 0.01M Al(NO3)3 aqueous solution. Various compositions of composite coating were obtained by controlling several electrochemical parameters, such as solution concentration, applied potential, deposition time and different sintering conditions. Its characterization was conducted by using potentiostat, SEM/EDS, XRD, immersion test, wear test and scratch test. The alumina coating has a better quality in resistance corrosion and wear, but the zirconia coating is more close to metal substrate than alumina coating. Depend on this, first electrolytic deposition of zirconia then deposition of alumina on Co-Cr-Mo alloy. Controlling aqueous concentration, electrolytic deposition of potential and deposition time. To expect obtain better property ceramic thin flim. Cycle polarization tests in Hank,s solution indicate that the Al2O3/ZrO2 coating has a better quality in resistance corrosion than the single Al2O3 or ZrO2 ceramic thin film. The scratch test of Al2O3/ZrO2 coating, in the vestige end part of alumina and zirconia still remains on the Co-Cr-Mo alloy from SEM/EDS analysis. Al2O3/ZrO2 ceramic thin film can to protect Co-Cr-Mo alloy from immersion test. From wear-corrosion behaviour the wear test influence the substrate serious than Al2O3/ZrO2 ceramic thin film deposition on substrate. In the corrosion potential and dissolution current of unimplanted Co-Cr-Mo and Al2O3/ZrO2 ceramic thin film deposition on substrate. Al2O3/ZrO2 ceramic thin film deposition on substrate unrestricted. From all kinds of analysis to show that electrolytic deposition of Al2O3/ZrO2 ceramic thin film on Co-Cr-Mo alloy have good properties.
48
Tsai, Yi-Lin, and 蔡易霖. "Synthesis of Large-Area Graphene Layer from Fe-Ni-Cu-Mn Alloy." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/kw7kq9.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
材料科學與工程研究所
100
This research used the liquid phase of Fe-Ni-Cu-Mn alloy to dissolve graphite powder; precipitate then synthesis to a large-area graphite layer on the surface of the alloy. We made use of a smelting vacuum furnace at 1350 ℃ for up to 5 hours to obtain the various samples in different alloy power ratios. And, we found some formulas which can produce a large-area graphene. According to our observation, A proper dendrite structure collocate a fine graphite wrinkle which will help the forming of partition phenomenon between graphite layers. In other words, the van der Waals bond might be vanished between graphite layers, so the graphite disassemble into the folded graphenes. According to this research, copper plays an important role of controlling the segregation of carbon, and manganese enhances its ability. The partition phenomenon then take place dramatically in some alloy formulas. Finally, we separate its folded graphene film from the alloy surface by means of etching. The maximal area of graphene is about 2500μm2 We also observed the surface of the graphene to check the relation of appearance and graphene area by a simple location skill. Therefore, we can understand the principle to form the large area graphene layer by liquid phase metals, so as to be the foundation of application of high quality graphene layers.
49
Hsieh, Chih-Hung, and 謝志宏. "Study on Corrosion Resistance of Copper-Zinc Alloy by Multi-layer Coating." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/afw266.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
資源工程研究所
106
Copper-zinc alloy is the most important material in terms of electronic connectors. Most of the connector industries apply a protective layer by electroplating on the surface of alloy material. Traditional protective layer consists of nickel-plating on the first layer and tin-plating on the surface layer. This research puts major emphasis on multi-layered plating of the alloy material. Design of protective layer is copper-plating on the first layer, nickel-plating on the second layer, and tin-plating on the appearance. Under the requirement of the steady production quantity and maintaining the same operating time of the process and output voltage of the electroplated metal, first of all, we conducted the electroplating process with an additional copper electroplating procedure in the continuous electroplating process. Second, after finishing the electroplating, we observe the crystal structure of the surface of electroplated material by the electron microscope. Finally, we tested the corrosion resistance of multi-layered plating process with salt spray test. The proposed experimental procedure is as follows. First of all, on a basis of the fixed electroplating time and fixed output voltage of the electroplated metal, we apply electroplating by an additional copper electroplating procedure of the continuous electroplating process. Second, under the requirement of electroplating on the alloy material with the same total film thickness following the original specification, we do not change the film thickness on the surface tin-plating layer, but decrease the film thickness of nickel-plating layer of the original alloy material and add a first copper-plating layer of the original alloy. It is able to achieve the same total thickness as the original double-layered plating does. Finally, we observe the multi-layered and double-layered plated samples after they are under salt spray trial. The analysis indicates that multi-layered plating performs better than double-layered in terms of the corrosion resistance.
50
Hsiao, Yo-Cheng, and 蕭祐晟. "Preparation of high emissivity layer on titanium alloy by micro-arc oxidation process." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/01333922336244322829.
Повний текст джерелаАнотація:
碩士中華大學
機械工程學系
105
There are various high emissivity heating pads in the market, however the medical performance of some heating pads is still open to discussion. The traditional infrared heating sources are mostly from electric wire and carbon fiber based composites. Unfortunately, they exist serious energy loss problems during energy transfer which needs to be improved. This study aims to prepare a high emissivity layer on titanium metal by micro arc oxidation process. The energy loss problems can be significantly improved because emission layer and substrate are integrated into one body. Other advantages of titanium metal to be applied in medical devices includes excellent biocompactivity and safety. The micro arc oxidation technology.is mature for surface treatment of titanium alloy and biocompactivity. However, related studies regarding MAO treatment for ultrathin titanium alloy and effects of process parameters on emissivity of oxide layer are still lacking. In this study, a rough and porous titanium oxide coating) will be applied on a 0.1and 0.07 -mm thick titanium metal sheet by using a microarc oxidation process, The parameter effects of the microarc oxidation process including the cathode voltage and process duration on the structure, surface morphologies, and thickness of the oxide layer were investigated. The emissivity of the oxide layer was measured by infrared thermal image analyzer. The highest emissivity of titanium oxide layer can achieve 0.96.