Tesis sobre el tema "Plasma sprayed ceramics"
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Kadhim, Mohammed Jasim. "Laser cladding of ceramics and sealing of plasma sprayed zirconia based thermal barrier coatings". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/11288.
Texto completoPark, Hyuen Me (Mia) Park. "Numerical and experimental analysis of stress behavior of plasma-sprayed Bioglass on titanium /". Full text open access at:, 1996. http://content.ohsu.edu/u?/etd,587.
Texto completoLongchamp, Vincent. "Modélisation du comportement de céramiques projetées plasma sous choc par simulation discrète à l'échelle de la microstructure". Electronic Thesis or Diss., Paris, HESAM, 2024. http://www.theses.fr/2024HESAE018.
Texto completoCeramic coatings obtained by plasma spraying (APS) have a porous, micro-cracked microstructure that has a significant effect on mechanical properties when subjected to micro-debris impact or laser shock.The microstructure attenuates compression waves, which can be useful for protective applications.Consequently, characterization of the microstructure-properties link, under dynamic loading, is necessary to exploit the potential of these materials, but understanding of the mechanisms involved is still limited.This thesis focuses on the possibilities offered by the discrete element method (DEM) for modelling heterogeneous materials such as plasma-sprayed ceramics at the microstructure scale. A strategy for creating 3D numerical domains representing the microstructure is proposed. It is based on the analysis of volume images obtained by FIB-SEM: porosity is detected and then processed according to its scale, in order to be reproduced digitally. Simulations are carried out on the models to study the effect of the microstructure on the propagation of compression waves, to obtain macroscopic behavior laws and to study the induced damage
Fox, A. C. "Gas permeation through plasma sprayed ceramic coatings". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599155.
Texto completoErickson, Lynn C. "Wear and microstructural integrity of ceramic plasma sprayed coatings". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0008/NQ38881.pdf.
Texto completoZhao, Jian. "Modelling damage and fracture evolution in plasma sprayed ceramic coatings : effect of microstructure". Thesis, Loughborough University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421924.
Texto completoHansel, Jason Edgar. "The Influence of Thickness on the Complex Modulus of Air Plasma Sprayed Ceramic Blend Coatings". Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1228478738.
Texto completoGonçalves, Fernando de Almeida. "Caracterização de revestimento de titânia aplicado por aspersão térmica a plasma em liga Ti-6A1-4V para aplicação em implantes". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263529.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A necessidade de melhorar as características superficiais da liga Ti-4Al-6V usada em implantes ortopédicos, levou à pesquisas no sentido de estudar a modificação da superfície dos implantes através da deposição de revestimentos cerâmicos resistentes à corrosão, ao desgaste e biocompatíveis, por vários métodos: eletroquímica, física a vapor, eletroforética, por sol-gel, biomimética e por aspersão térmica a plasma, entre outras. A aspersão térmica a plasma é o processo mais utilizado comercialmente, pois é rápido e reprodutível. As biocerâmicas mais utilizadas para revestimento, com sucesso, são as de fosfato de cálcio (hidroxiapatita-HA, betafosfato tricálcico [o -TCP] e uma mistura dessas duas fases). A adesão dessas biocerâmicas ao tecido ósseo possuí bom desempenho é bastante discutida na literatura. A comunidade médica tem algumas restrições ao uso desses implantes metálicos revestidos por cerâmicas, com relação à interface metal-cerâmica, cuja adesão é considerada baixa. Neste trabalho foi estudado a adesão metal/cerâmica em implantes revestidos por aspersão térmica à plasma (ATP) com cerâmica, mais especificamente liga de titânio (Ti-6Al-4V) revestida com titânia (TiO2) sem e com tratamento térmico a vácuo, com o intuito de verificar uma possível melhoria nessa adesão. A cerâmica utilizada neste trabalho foi a titânia, uma vez que é uma cerâmica biocompatível e osseointegrável, que é bastante utilizada para revestir implantes. Para a execução do trabalho foram confeccionados diversos corpos de prova, os quais foram revestidos por titânia por aspersão térmica à plasma, tratados termicamente e caracterizados segundo procedimentos contidos em normas e trabalhos científicos correlacionados que norteiam o assunto proposto. Foram utilizadas as seguintes técnicas de caracterização: análise granulométrica dos pós cerâmicos, difração de raios X, verificação da porosidade, microscopia óptica e eletrônica de varredura, verificação da rugosidade das amostras. Especial ênfase foi dada aos ensaios de adesão metal-cerâmica: ensaios de adesão por tração, flexão e riscamento. Tentou-se utilizar, sem sucesso, os ensaios de microdureza para avaliar a adesão. Como resultados, verificou-se uma boa qualidade nas amostras da liga Ti-4Al-6V revestidas por titânia por aspersão térmica a plasma. Através das três técnicas de avaliação da adesão, verificou-se uma ligeira melhoria dessas características pelo tratamento térmico a vácuo, no ensaio de riscamento a carga crítica aumentou de 53N para 62N, no ensaio de tração a tensão de fratura aumentou de 10,5MPa para 17,4MPa e no ensaio de flexão a tensão de fratura aumentou de 153,3MPa para 193,1MPa. Comparando com valores encontrados na literatura, a adesão Ti-4Al-6V/TiO2 ficou superior a Ti-4Al-6V/HA nas mesmas condições de deposição
Abstract: The need to improve the surface characteristics of the alloy Ti-4Al-6V used in orthopedic implants, increase researches with the focus into the surface modification, using deposition of ceramic coatings resistant to corrosion, wear and more biocompatible by various methods: electrochemistry, physical vapor, electrophoretic, by sol-gel, biomimetics and by thermal plasma, among others. The plasma spray technique is the process more used commercially because it is fast and reproducible. The bioceramics most used for coating, are calcium phosphate (hydroxyapatite-HA, beta-tricalcium phosphate, o -TCP and a mixture of these two phases). The adhesion of these bioceramics to the bone tissue is quite discussed in literature, presenting a good performance. However, the medical community has some restrictions on the use of metal implants with ceramic coating, since the metal-ceramic interface is considered low. In this work the aim is to study the adhesion metal/ceramic-coated implants in the thermal spray plasma (ATP), using titanium alloy (Ti-6Al-4V) coated with titania (TiO2) with and without vacuum heat treatment in order to check a possible improvement this adherence. The ceramic used in this work was the titania, since it is biocompatible and bioactive, and it is quite used to coat dental implants. For the execution of the work were made several specimens, which were coated with titania by plasma thermal spray, heat treated and characterized according to procedures and standards contained in scientific papers related to guide the proposed subject. The following characterization techniques it were used: particle size analysis of ceramic powders, X-ray diffraction, analysis of the porosity, optical microscopy and scanning electron microscopy, scanning the roughness of the samples. Special emphasis was given to tests of metal-ceramic adhesion: adhesion assays for tensile, bending and scratching. Micro hardness tests carried out, however the results were not significant. The summary of this project were that this alloy present a good quality coated by titania. The methods of increase the adhesion, showed a slight improvement of these characteristics by vacuum heat treatment, the result of the scratching test showed that the critical load increase to 62N instead 53N, when analyzed the results of tensile test it also had an increase 17,4MPa instead 10,5 MPa, the bending test presented higher results 193,1MPa in contrast to 153,3MPa for the samples without treatment. Compared with values found in the literature, the adherence of Ti-4Al-6V/TiO2 was greater than Ti-4Al-6V/HA
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
Siegert, Roberto. "A novel process for the liquid feedstock plasma spray of ceramic coatings with nanostructural features". [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980671728.
Texto completoAubignat, Emilie. "Contribution à la compréhension et à la maîtrise du procédé de projection plasma de suspensions céramiques". Thesis, Belfort-Montbéliard, 2014. http://www.theses.fr/2014BELF0238.
Texto completoSuspension plasma spray (SPS) is a surface coating process that consists in injecting a suspension (solid particles of about 1 μm or less, dispersed in a liquid phase) in a high-energy plasma flow. Particles are heated, accelerated towards a substrate, flattened and submitted to a rapid solidification (order of 106 K.s-1). Layer after layer, a coating is formed on the substrate surface and brings new functional properties. This variation of the conventional plasma spray process allows the manufacturing of coatings with finer thickness of few tens of μm and a reduced structural scale that can lead to improved coating properties, like hardness or thermal conductivity. Even though this process has been studied since the middle of the 1990’S and known a fast-growing interest, industrial applications are not finalized and their development needs to be pursued. Indeed, the suspension injection in a thermal jet leads to complex phenomena such as suspension droplet fragmentation or liquid phase evaporation. Up to now, these mechanisms are not perfectly understood and controlled and deserve to be further studied to understand interactions between these fine particles and the plasma. This thesis focuses on the SPS process with ceramic suspensions and a twin-fluid nozzle as injection system. Two materials were chosen: alumina, known for its difficulty to be conventionally sprayed and whose crystalline phase formation represents a source of information about particle thermal history, and also yttria, in order to confirm the tendencies observed for alumina. Firstly, the suspension injection was optimized by working on two areas. The first area concerns suspension formulation. This led to obtain, with different liquid phases, stable and dispersed suspensions, whose properties are perfectly known. Such suspensions ensure reproducibility of the process at this level and limit the risk of injection system clogging. The second area is about the three-step mechanical conception of a pneumatic atomizer, adapted to the SPS process. This study began with the characterization of a commercial nozzle, in particular by testing the suspension injection into a plasma flow. Tests being little convincing, the study was carried on with the development of a new atomizer geometry, inspired from the commercial model. Trials drove to the manufacturing of satisfying spray beads and coatings. This study was finally completed with the optimization of this new geometry by highlighting the influence of several key parameters on the atomized jet features. Secondly, diagnostic tools were implemented to qualify the injection. Suspension jet was characterized in terms of geometry and droplet sizes, using respectively shadowgraphy and laser diffraction. Shadowgraphy was used again for optimizing the suspension injection into plasma by allowing the adjustment in real time of inlet atomizer pressures. In-flight particle properties were then studied thanks to particle collection onto a substrate and particle image velocimetry (PIV). This tool also provided additional information on the suspension injection. Finally, the resulting coatings were characterized in terms of morphology (SEM), porosity rate (SEM image analysis and USAXS) and crystalline phases (DRX and EBSD). The cross-checking of the information obtained with all these techniques brought out the role of the suspension liquid phase and of the mass load on the coating microstructure. These works contributed to enhance the knowledge about the SPS process and justified the use of a twin-fluid nozzle to obtain specific microstructures of coatings, whose functional characterizations have still to be done
Zoghbi, Bassem El. "Modélisation et étude numérique de la fissuration lente des céramiques : influence de la microstructure et de l'environnement. Application aux céramiques élaborées par projection plasma". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI007/document.
Texto completoCeramic materials are prone to slow crack growth (SCG)due to the combined effect of the mechanical loading and the environment (moisture and temperature).Based on atomistic studies available in the literature,a thermally activated cohesive model is proposed to represent the reaction-rupture mechanism underlying slow crack growth. The description is shown able to capture SCG under static fatigue on ceramic single crystals as well as intergranular SCG in polycrystals.We emphasize that the representation of SCG with the crack velocity versus the energy release rate G accounts for the intrinsic characteristics of SCG, which is preferable than a usual plot with V-K curves.The cohesive model incorporates a characteristic length scale, so that size effects can be investigated. SCG is grain size dependent with the decrease of the crack velocity at a given load level and improvement of the load threshold with the grain size. To capture this observation, account for the initial thermal stresses related to the processing is mandatory. SCG is also dependent on the concentration of water with an increase of the crack velocity and a decrease of the load threshold with the relative humidity increasing. To predict this effect, the cohesive description needs to account for activation energy and a threshold to trigger the reaction-rupture that depends on the concentration of water. The influence of the temperature on SCG shows an increase in the crack velocity and a decrease of the load threshold for SCG due to the reduction in the initial thermal stresses. The SCG behavior of the alumina and zirconia is compared. Zirconia exhibits a better resistance to SCG compared to that of alumina, in the absence of any phase transformation due to lower kinetics of its reaction-rupture. Based on these results, SCG is investigated in plasma sprayed ceramic. An initial damage at the scale of the splats is observed without effect on load threshold G0 for SCG in V-G plots
Jadhav, Amol D. "Processing, characterization, and properties of some novel thermal barrier coatings". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1183851697.
Texto completoKane, Kenneth. "Metallic systems at the nano and micro scale: Bimetallic nanoparticles as catalysts and MCrAlY bond coats in thermal barrier coatings". VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5732.
Texto completoThomas, Gareth James. "Advanced materials for plasma facing components in fusion devices". Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:f8ba1ae1-f303-4c32-877e-dca421a3cb5c.
Texto completoSamadi, Hamed. "A Thick Multilayer Thermal Barrier Coating: Design, Deposition, and Internal Stresses". Thesis, 2009. http://hdl.handle.net/1807/19086.
Texto completoSmith, Raymond F. "The characterization of cermet and ceramic plasma-sprayed coatings using four-point bend flexure experiments". 1996. http://catalog.hathitrust.org/api/volumes/oclc/37229908.html.
Texto completoTypescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 65-67).
Lian, Jenn-Chang y 連振昌. "The study of wear life and fracture behavior of plasma sprayed aluminium oxide ceramic coating". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/67666743442547528399.
Texto completoLin, Weei Bang y 林偉邦. "Surface and Microstructural Modifications of Al2O3 and/or 8YPSZ Plasma-Sprayed Ceramic Coatings by Laser remelting". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/08720157924254563437.
Texto completoZarzalejo, Maria. "Design and Development of Atmospheric Plasma Sprayed Ceramic Anodes for Solid Oxide Fuel Cells Operating under High Fuel Utilization Conditions". Thesis, 2012. http://hdl.handle.net/1807/42429.
Texto completoChou, Chun-Hung y 周俊宏. "The Simulation Analysis of the Process of Ceramic Membrane Preparation by Atmospheric Plasma Spray Coatings". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/75886869977933023311.
Texto completo中原大學
化學工程研究所
95
Air plasma spraying process was wildly used to produce ceramic membranes and thermal barrier coatings in industry field. It has been well-known that the particles melting status and its in-flight velocity was the most important factors that affect the lamellar formation and porosity. The interaction of particles with the plasma jet is crucial to the coating properties. However, direct measurement of particle heating history was difficult in experiments because of its residence time is extremely short. All the information concerning particle melting state can’t thoroughly get from on-line monitor facility. Hence, numerical models have been developed to investigate the in-flight particle melting behavior during spraying process by computational fluid dynamics program FLUENT V6.2©. The purpose of this study was focus on particles trajectory , heating history as well as its in-flight velocity under various carrier gas flow rate. In this study, the argon plasma jet is simulated. The alumina particle trajectories were tracked in Lagrangian manner. The results show that the spray-angle will increase as carrier gas flow rate enhance. The phenomenon is more obvious in internal powder injector than external one. As carrier gas flow rate increase , the maxium velocity of plasma jet will lift up and its maxium temperature will decrease. Particle with internal powder injection has better in-flight velocity and surface temperature than external one. This was due to the location of powder injector. Internal type was much closer to the heating and heart core of plasma jet which resulted in longer heating time and better melting status than external one. The former has higher particle mean surface temperature than latter as we further check particle counts distributions at standoff distance equal to nine centimeter. We use Biot number to analysis the melting state as particle surface temperature reach its melting point and integral mean thermal conductivity was used in this work. The results indicate that there still have fourteen percentage difference between surface temperature and its center point. As far as particle evaporation state be concered, particle residence time was shorter than its evaporation time. It seems like the phenomena wasn’t play an important role in this study. Furthermore, Particle injection velocity under different carrier gas flow rate resulted from ranges of corresponding particle size and injection location. Particle penetration depth mainly relied on its momentum and particle size. particle injection with external injector will be dispersed by plasma jet because of insufficient in momentum.The dispersion location for internal type was more concentrate than external type. At last but not least, CFD simulation tool have been developed in this study. It will help us analysis how the process variable affect the coating properties.
Siegert, Roberto [Verfasser]. "A novel process for the liquid feedstock plasma spray of ceramic coatings with nanostructural features / von Roberto Siegert". 2005. http://d-nb.info/980671728/34.
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