Dissertations / Theses on the topic 'Erosione arch'
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1
PIGAZZINI, ILARIA. "Evaluating and Detecting Architecture Erosion." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/365009.
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Un'architettura software è erosa (o degradata) se mostra una progressiva perdita di integrità strutturale a causa di violazioni dei principi di progettazione. I sistemi erosi soffrono di Architectural Technical Debt (ATD), lo sforzo aggiuntivo richiesto agli sviluppatori per gestire i difetti causati dall'erosione. Un sintomo dell'accumulo di ATD è la presenza di Architectural Smells (AS), decisioni di software design che hanno un impatto negativo sulla qualità interna del sistema software. I sistemi affetti da AS soffrono di maggiori costi di manutenzione e sono più difficili da evolvere. Questa tesi indaga sei diversi tipi di AS che violano diversi principi di design in progetti Java monolitici Open-Source e industriali. Identifichiamo gli AS con il nostro strumento, Arcan, e introduciamo la sua nuova estensione per la rappresentazione dei software concerns. Discutiamo poi gli AS dal punto di vista dei professionisti, cercando di riassumere come gli AS sono percepiti e validando i risultati di Arcan. Riportiamo anche i risultati dei nostri studi empirici riguardanti l'evoluzione e la correlazione di AS e ATD. Infine, presentiamo i nostri primi risultati riguardanti la migrazione e la manutenzione di architetture a microservizi, con particolare attenzione al rilevamento degli odori dei microservizi.A software architecture is eroded (or degraded) if it shows a progressive loss of structural integrity due to design principle violations which leads to the deviation of the implemented architecture from the intended architecture. Eroded systems suffer from Architectural Technical Debt (ATD), the additional effort required by developers to manage the shortcomings caused by the erosion. A symptom of the accumulation of ATD is the presence of Architectural Smells (AS), design decisions that impact negatively on the internal system quality. Systems affected by AS suffer from higher maintenance costs and are harder to evolve. This thesis investigates six different types of AS violating different design principles in Open-Source and industrial monolithic Java projects. We identify AS with our tool, Arcan, and introduce its new extension for the representation of software concerns. We then discuss AS from the point of view of practitioners, trying to summarise how AS are perceived and validating Arcan results. We also report the results of our empirical studies concerning AS and ATD evolution and correlation. Finally, we present our first results concerning the migration and maintenance of microservices architectures, with a focus on the detection of microservices smells.
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Seon, Hongsun 1965. "Electrode erosion and arc stability in transferred arcs with graphite electrodes." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=108637.
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Arc stability and erosion behavior were studied on a hollow graphite DC cathode in an argon atmosphere at atmospheric pressure. It was found that the arc stability is associated with the electron emission mode transition of the cathode operation. Estimation of current densities, SEM pictures, Fast Fourier Transform (FFT) of total voltage, and measurement of cathode surface temperature supported this. Stable arcs are in the thermionic emission regime while unstable arcs in the thermofield emission regime. Higher argon gas flow rate is believed to cause the shift of the mode from the thermofield emission to the thermionic emission by increasing the arc root temperature through steepening the thermal gradient at the arc root and increasing ionization phenomena inside the arc. Sharp cathode tip geometry usually leads to the thermionic emission while a rounded tip geometry encourages the thermofield emission. For the unstable arcs, the high voltage fluctuation resulted from the jumping of the arc root between different cathode spots and changes in the arc length. In the stable arcs, however, the voltage was almost constant because of the absence of arc jumping. The standard deviation of the voltage was used as the arc stability indicator and was less than 3 V for the stable arc in this transferred arc system.The erosion rate of the cathode in this work ranged from 0.41 to 2.61 mug/C. At 150 A runs the arc stability strongly influenced the erosion rate; as the arc stability increased, the erosion rate decreased. Higher currents runs (300 and 400 A), however, showed the opposite trend because of the carbon vapor redeposition. The total erosion rates of 150 A runs were separated into the stable (Es) and the unstable (Eu) erosion rate. The Eu was more than 3 times higher in this work. It is believed that the thermofield emission of the unstable arcs produced more erosion because of the higher local heat flux to the cathode spots.
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Schneider, Wolfgang. "Studies on arcing phenomena at high current discharges." Thesis, University of Essex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310044.
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Szente, Roberto Nunes. "Cathode erosion in magnetically rotated arces." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65438.
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Cunha, Matheus Araújo da. "Influência do tipo de erodente à base de alumina na incrustação em um revestimento de FeCr, aspergido por arco elétrico, empregado em ensaios de desgaste erosivo, à temperatura ambiente e a 400ºC." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/115272.
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Este trabalho investigou a influência do tipo de erodente à base de alumina na incrustação em um revestimento metálico à base de FeCr, aspergido por arco elétrico, empregados em ensaios de desgaste erosivo, tanto à temperatura ambiente como a 400°C, com ângulo de incidência entre o erodente e a superfície de 30° e 90° e velocidade de projeção de 25 m/s. Como erodente, utilizou-se alumina eletrofundida com faces anguladas e irregulares e também alumina calcinada com formando aglomerados esferoides. O revestimento dos corpos-de-prova foi caracterizado quanto à morfologia (MEV), porosidade, densidade aparente, análise térmica, espessura da camada depositada, taxa de erosão e mapeamento de elementos por espectrometria de energia dispersiva (EDS). Os erodentes foram caracterizados quanto a sua morfologia (MEV), distribuição granulométrica e área superficial (BET). Os resultados mostraram que à temperatura ambiente os ensaios realizados com alumina calcinada com ângulo de 30° e alumina eletrofundida a 90° foram os que apresentaram maiores quantidades de alumínio incrustado no revestimento para uma mesma área de análise. Os ensaios realizados com a alumina eletrofundida com ângulo de 30° foi a que apresentou a maior taxa de erosão. Já a distribuição granulométrica e área superficial dos erodentes após ensaio de erosão apresentaram uma diminuição em relação aos valores de antes do ensaio. Os ensaios realizados a 400°C de temperatura mostraram que a alumina calcinada, para os dois ângulos de ensaio, resultou em maior incrustação no revestimento ensaiado, sendo maior para o ângulo de 90° do que para o ângulo de 30°. Para essa temperatura de ensaio, a maior taxa de erosão ocorreu para o ensaio conduzido com ângulo de 30°, utilizando alumina calcinada. Ainda para os ensaios a 400°C, os resultados para o tamanho médio de partícula na distribuição granulométrica indicaram uma redução nos valores iniciais para todos os ensaios realizados. No entanto, a área superficial de ambos erodentes permaneceu com valores muito próximos ao de antes do ensaio.This work investigated the influence of the kind of erodent based on alumina embedded in a metallic coating based on FeCr, sprayed by arc electric technique, used in erosive wear test at room temperature and 400°C with angle of incidence between the erodent and the surface of 30° and 90° and erodent velocity of 25 m/s. As erodent was used fused alumina that showed angled and irregular surfaces and also calcined alumina forming spheroids agglomerates. The coating of the samples was characterized morphology (SEM), porosity, density, thermal analysis, the layer thickness, erosion rate and mapping of elements by energy dispersive spectrometry (EDS). The erodent was characterized by their morphology (SEM), particle size distribution and surface area (BET). The results showed that the room temperature tests performed with alumina calcined with angle of 30° and fused alumina with angle of 90° were those with larger amounts of aluminum embedded in the coating to the same area of analysis. Tests performed with the electro alumina with angle of 30° were presented the highest rate of erosion. Already the particle size distribution and surface area of erodent after testing erosion showed a decrease compared to the values before the test. The tests performed at 400°C temperature showed that the calcined alumina for the both angles test resulted in greater embedded of aluminum in the tested coating, being higher for the 90° angle than the angle of 30°. For this test temperature, the higher erosion rate occurred for the experiment with 30° angle using calcined alumina. Also for the tests at 400°C, the results for the average particle size in the particle size distribution showed a reduction in initial values for all tests. However, the surface area of erodent remained with both values very close to that of before the test.
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Pons, Frédéric. "Electrical contact material arc erosion: experiments and modeling towards the design of an AgCdO substitute." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33816.
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AgCdO is one of the most widely used contact materials in the world because of its outstanding performance. Nevertheless, due to environmental considerations, it will soon be completely forbidden by European environmental directives. Therefore, finding a good substitute is of crucial importance.
Electrical arc erosion plays a crucial role in the reliability and life of power switching devices. Depending on the contact material's behavior in response to an electrical arc, surface damage can induce severe changes in contact material properties that will impact the power switching device's functioning. Consequently, electrical arc effects and consequences on the contact material surface are of first importance.
In this context, we have focused our research activities on the following axes.
First of all, in order to better understand AgCdO (Current contact material in aerospace industry) and AgSnO₂(Potential candidate to AgCdO substitution) arc erosion behaviors, arc erosion experiments, where the power switching devices have been subjected to different numbers of arc discharges, have been realized.
Further, a general macroscopic electrical contact arc erosion model valid for low and high currents was developed. To compare model results to experimental data, this model describes the complete breaking process of electrical contacts and gives the total amount of material removed after one breaking operation. In parallel, arc erosion experiments on AgCdO power switching devices have been conducted at high currents (0
-> 1000 A) in order to validate the arc erosion model.
Next, using the general arc erosion model, the properties having the greatest
influence on the electrical arc erosion process have been determined through simulations
on silver contact material. At this stage, ab initio calculations were needed to obtain
ranges of variation of certain silver contact material properties.
Finally, an investigation of the trends of changing local contact material on these identified material properties was performed. This study composition of AgSnO₂was based on ab initio calculations for two different oxide compositions of AgSnO₂.
These will allow us to give directions to aid the design of a good substitute for AgCdO, and therefore, to complete the main objective of this research work.
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Sumption, Alan. "The evolution of break arc erosion from arc initiation to extinction on silver alloy electrical contacts in low voltage DC switches." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/47499/.
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This study concerns the evolution of electrical contact erosion in low voltage 42V DC (24A) applications. The aim is to describe the erosion mechanisms of a single arc discharge at both contact surfaces during operation. To this end the experiments conducted are designed to produce results that enable close examination of the surface profile changes, volumetric contact material movements, and relative quantities of metallic and gaseous species in the arc discharge. The experimental procedure is arranged so that the contacts undergo a low number of operation cycles in order to limit the cumulative effects of arc erosion. To obtain results portraying the evolution of arc erosion in a 42V system the apparatus allows for interruption of the arc at any desired voltage level. A series of tests are conducted at specified voltage steps from arc initiation to extinction. The samples collected are analysed using a non-contact laser profile apparatus giving 2D and 3D surface scans. During each arc discharge a record of spectral emissions is collected by a spectrometer and later analysed to show the constituents of the arc. The data is represented with reference to voltage level and shows how the erosion evolution from a low number of operation cycles is related to arc phenomena. In addition the voltage profiles of the arc are recorded and represented by amplitude modulation. It has been found that the erosion site dimensions are related to the arc voltage fluctuations. In these tests a marked change of voltage slope is seen but is not found to be related to the metallic to gaseous phase transition as often thought. It is determined that the anodic to cathodic arc transition is not due to a metallic to gaseous phase transition. Changes in surface profile at the cathode occurring during the cathodic arc phase, and before gaseous phase initiation, are affected by density per unit area of ions impacting the surface. The vaporization of the cathode requires a critical ion density. This determines the anodic to cathodic transition point. Conversely the anode is thought to endure intense electron sputtering throughout the arc lifetime and its volumetric loss is greater than that of the cathode.
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Pons, Frédéric. "Erosion suite à l'impact d'un arc électrique : modélisation et campagnes expérimentales en vue du développement d'un matériau de substitution à l'alliage AgCdO." Thesis, Metz, 2010. http://www.theses.fr/2010METZ039S/document.
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L’AgCdO est l’un des matériaux de contact parmi les plus répandus dans le monde du fait de ses excellentes propriétés. Cependant, étant donné la présence de Cadmium dans celui-ci, il sera bientôt totalement interdit par des directives européennes d’ordre environnementales. Trouver un matériau ne contenant pas de Cadmium et ayant au moins d’aussi bonnes propriétés est donc la clé du projet. Le phénomène d’érosion du matériau de contact suite à l’impact d’un arc électrique joue un rôle de premier ordre dans la fiabilité et la durée de vie des dispositifs de commutation de puissance. Celui-ci influe en effet sur les propriétés du matériau et affecte ainsi le fonctionnement du dispositif de commutation de puissance. Dans ce contexte, nos axes de recherche ont été les suivants. Avant tout, et ce afin de mieux comprendre le comportement à l’érosion suite à l’impact d’un arc électrique de l’AgCdO (matériau de contact utilisé actuellement dans l’industrie aérospatiale) et celui de l’AgSnO2 (candidat potentiel au remplacement de l’AgCdO), des essais ont été réalisés en soumettant les dispositifs de commutation de puissance à différents nombres de décharges. Ensuite, un modèle macroscopique permettant de prédire l’érosion d’un matériau suite à l’impact d’un arc électrique, valable pour faibles et forts courants, a été développé. Ce modèle décrit le processus complet de coupure et donne la quantité totale de matériau érodé suite à une opération de commutation. En parallèle, des essais ont été réalisés sur des dispositifs de commutation de puissance AgCdO à forts courants (0 -> 1000 A) afin de valider ce modèle d’érosion. Les propriétés matériau les plus influentes sur le processus d’érosion ont ensuite été déterminées à l’aide de ce modèle. Enfin, une étude ab initio portant sur les effets d’un changement de composition locale du matériau sur ses propriétés identifiées comme influentes sur le processus d’érosion a été réalisée. Ainsi, l’ensemble de ces travaux permettront de conclure sur des directives dans l’élaboration du matériau de contact qui remplacera l’AgCdO, objectif principal de ces travaux de rechercheAgCdO is one of the most widely used contact materials in the world because of its outstanding performance. Nevertheless, due to environmental considerations, it will soon be completely forbidden by European environmental directives. Therefore, finding a good substitute is of crucial importance. Electrical arc erosion plays a crucial role in the reliability and life of power switching devices. Depending on the contact material’s behavior in response to an electrical arc, surface damage can induce severe changes in contact material properties that will impact the power switching device’s functioning. Consequently, electrical arc effects and consequences on the contact material surface are of first importance. In this context, we have focused our research activities on the following axes. First of all, in order to better understand AgCdO (Current contact material in aerospace industry) and AgSnO2 (Potential candidate to AgCdO substitution) arc erosion behaviors, arc erosion experiments, where the power switching devices have been subjected to different numbers of arc discharges, have been realized. Further, a general macroscopic electrical contact arc erosion model valid for low and high currents was developed. To compare model results to experimental data, this model describes the complete breaking process of electrical contacts and gives the total amount of material removed after one breaking operation. In parallel, arc erosion experiments on AgCdO power switching devices have been conducted at high currents (0 -> 1000 A) in order to validate the arc erosion model. Next, using the general arc erosion model, the properties having the greatest influence on the electrical arc erosion process have been determined through simulations on silver contact material. At this stage, ab initio calculations were needed to obtain ranges of variation of certain silver contact material properties. Finally, an investigation of the trends of changing local contact material composition of AgSnO2 on these identified material properties was performed. This study was based on ab initio calculations for two different oxide compositions of AgSnO2. These will allow us to give directions to aid the design of a good substitute for AgCdO, and therefore, to complete the main objective of this research work
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Collot, Jean-Yves. "Obduction et collision : exemples de la Nouvelle-Calédonie et de la zone de subduction des Nouvelles-Hébrides." Paris 11, 1989. http://www.theses.fr/1989PA112401.
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Deux cas particuliers d'évolution de la lithosphère océanique aux frontières de plaques sont examinés en utilisant les méthodes modernes de la géophysique marine. Le premier est celui de l'abduction d'une nappe ophiolitique sur un fragment continental en Nouvelle-Calédonie et le second celui de la déformation de la lithosphère de l'arc insulaire des Nouvelles-Hébrides en réponse à la collision d'aspérités topographiques portées par la plaque plongeante. La nappe ophiolitique de Nouvelle-Calédonie s'est mise en place tectoniquement à l'Eocène supérieur sur un substratum permien à éocène supérieur. Notre étude montre que cette ophiolite, épaisse au maximum de 10 km, résulte de l'obduction d'un fragment de lithosphère océanique du bassin des Loyauté adjacent à la Nouvelle-Calédonie. Cette abduction se serait accomplie sur environ 800 km, le long de la ride de Nouvelle-Calédonie, sans faire intervenir de collision continent-arc ou continent-continent. Nous discutons du contexte géodynamique de l'ophiolite au moment de sa rupture et de son abduction. La Zone d'Entrecasteaux (DEZ) et le Massif Ouest Torres sont deux aspérités topographiques sous-marines hautes de 1000 à 3000 rn qui entrent en collision et subductent sous l'arc insulaire des Nouvelles-Hébrides à 10 cm/an. La DEZ est légèrement oblique à la direction de convergence des plaques de telle façon qu'elle balaye l'arc vers le Nord à environ 2. 5 cm/an. L'analyse des structures de la plaque plongeante et de l'arc des Nouvelles-Hébrides centrales suggère que la déformation résultant d'une collision peut se développer dans des directions opposées. Dans le cas de la subduction/collision de la DEZ, la déformation se développe sur l'arc et affecte la marge qui s'épaissit et se soulève de 3 à 4 mm/an depuis le Pliocène terminal, le bassin intra-arc qui se fracture et subside et la zone arrière-arc qui se comprime et tend à chevaucher la bassin marginal adjacent. A l'opposé au sud de cette zone de collision, dans une région précédemment balayée par la DEZ, la déformation se développe vers l'océan depuis la marge qui s'effondre, jusque sur la plaque plongeante qui subit un raccourcissement. Bien que des indices d'accrétion sous la marge soient discutés, l'érosion tectonique de cette marge semble être un des phénomènes majeurs résultant de la collision et du balayage d'une aspérité topographique le long de l'arc.
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Nuber, Eduardo. "Evolução morfológica e sedimentológica do Arco Praial de Massaguaçú, litoral norte de São Paulo." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/21/21133/tde-30062009-145019/.
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Nesta dissertação apresenta-se a evolução morfológica e sedimentológica no Arco Praial de Massaguaçú, Litoral Norte do Estado de São Paulo, em uma escala espaço-temporal histórica e de eventos. O Arco Praial de Massaguaçú localiza-se ao norte da Baia de Caraguatatuba e tem uma extensão de aproximadamente 7,5km. A metodologia consistiu na determinação da variação da linha de costa através da análise de fotografias aéreas de 1962, 1977, 1994 e 2001 e GPS para 2006. Foram obtidos 174 perfis bidimensionais e 16 perfis tridimensionais coletados em cinco levantamentos de campos entre os meses de novembro de 2006 e março de 2008 utilizando o método de DGPS. Foram coletadas ainda 176 amostras sedimentares na zona de espraiamento do Arco Praial, junto ao último ponto de cada perfil bidimensional, sendo uma coleta por perfil. Os resultados demonstraram que a maior parte da praia sofreu progradação entre os anos de 1962 e 1994, sendo observada mudança nesta tendência entre 1994 e 2006. Os dados de morfologia e sedimentologia mostraram grande variabilidade espaço temporal, sendo que estas parecem estar relacionadas a variações anuais de energia de onda. Foi identificada uma Zona de Erosão Acentuada (ZEA) na Parte Central do Arco Praial e dividiu-se a praia em cinco áreas de risco, onde este é menor nas extremidades do Arco Praial e aumenta em direção a região central.This dissertation characterize the morphological and sedimentological evolution of Massaguaçú Bay Beach, São Paulo State, Northeast Brazil, in a Historical and events spatial-temporal scale. Massaguaçú Bay Beach is localized northward of Caraguatatuba Bay and has approximately 7.5Km length. The methodology consisted on the determination of the shoreline changes with Aerophotographic analyses of 1962, 1977, 1994 and 2001, 2006 shoreline was taken with GPS. The DGPS Method was used to obtain 174 two-dimensional profiles and 16 tri-dimensional profiles in 5 field campaigns conducted between November, 2006 and March, 2008. 176 sand samples were collect in the swash zone, next to the last position of each two-dimensional profile. Data showed that almost all beach demonstrated shoreline progradation between 1962 and 1994, this tendency change between 1994 and 2006 with the possibility of increase of the retraction processes. It was observed a great variability in morphological and sedimentological data, this appear to be related with variations on the wave height pattern during the year. It has identified an Erosional Hotspot in the central area of the beach and the beach has divided in five risck areas where the risck increase from the extremities to the center of the beach.
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Pellegrinon, Gabriel. "Analisi morfometrica e simulazione dinamica degli eventi di colata detritica avvenuti nell'estate del 2015 lungo il Rio Ravina di Cancia (BL)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18159/.
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Il carattere erosivo delle colate detritiche è poco compreso e studiato. Lo studio si propone di indagarne le caratteristiche nel contesto geomorfologico e idrologico unico di Cancia. Lo studio è condotto su 2 eventi del 2015 documentati con DEM pre- post- evento. Essi sono elaborati in ambiente GIS con cui sono sviluppati metodi automatici di analisi morfometrica applicabili ad altri casi. L'erosione idraulica del canale di flussi d'acqua da intense e brevi precipitazione origina colate detritiche con erosione fino a 7 m e deposizione in alternanza con erosione. Lo studio dimostra la dipendenza della pendenza percorsa sulle dinamiche erosivo- deposizionali dei fenomeni. l'analisi morfometrica funge da calibrazione per le simulazioni dinamiche di RAMMs- DF e DAN3D condotte senza e con erosione. La loro applicabilità di calibrazione è confermata senza erosione uguale alle simulazioni con erosione di DAN3D. L'applicabilità delle simulazioni calibrate con erosione di RAMMs-DF è limitata a causa dell'invalidità del suo criterio di arresto. L'erosione e la deposizione sono sconnesse dalla fisica reale degli eventi. La deposizione di DAN3D è in parte più simile. L'erosione di RAMMs-DF tende a riprodurre il fenomeno ma necessita di ulteriore sviluppo congiunto al miglioramento del suo criterio di arresto.
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Costa, Rodrigo Cardoso. "Desenvolvimento de novos revestimentos por aspersão térmica à arco para proteção contra desgaste erosivo em trocadores de calor ar/gases." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/70680.
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Uma alternativa à utilização de tubos de alto custo, resistentes a erosão por partículas sólidas, nos trocadores de calor ar/gases de usinas termelétricas a carvão, é o revestimento por aspersão térmica com ligas especiais de média a alta dureza. Dentre os processos de aspersão térmica, os mais usualmente empregados para a deposição de revestimentos contra desgaste são por HVOF (High-Velocity Oxyfuel), PS (Plasma Spraying) e AS (Arc Spraying). O processo aspersão térmica a arco (AS) propicia alta produtividade devido a uma maior taxa de deposição quando comparado com os outros processos, além do custo operacional significantemente mais baixo para a fabricação de revestimentos. Neste trabalho, foram depositadas por AS quatro ligas metálicas contra o desgaste erosivo a base de carboneto de tungstênio, superligas de níquel, ligadas ao boro e aço inoxidável martensítico em comparação ao aço ASTM 178 grau A, o qual é atualmente empregado nos tubos do trocador de calor. A avaliação foi feita a partir de ensaios de erosão acelerada (norma ASTM G76), metalografia e MEV. Verificou-se que o comportamento dos revestimentos contendo grande quantidade de defeitos, principalmente porosidade, quando expostos ao desgaste acelerado numa temperatura de 370°C, apresentaram uma maior taxa de desgaste em relação ao aço ASTM A178, e que o melhor comportamento dentre as ligas analisadas foi do aço inoxidável AISI 420 aspergido, o qual apresentou aproximadamente 2% de porosidade e um mecanismo de remoção de material predominantemente dúctil.An alternative to using tubes of expensive materials, resistant to erosion by solid particles in air-gases heat exchangers of coal power plants, is the thermal spray coatings with special alloys of medium to high hardness. Among the thermal spray processes, the most commonly employed for coatings against wear are HVOF (High-Velocity Oxyfuel), PS (Plasma Spraying) and AS (Arc Spraying). The arc thermal spray process (AS) provides high productivity, due to a higher deposition rate compared to other processes, in addition to the significantly lower operational cost. In this study four different alloys were deposited to evaluate the erosive wear resistance in comparison to the ASTM 178 Grade A steel (currently employed in the tubes of the heat exchanger): 1) with basis of tungsten carbide, 2) nickel superalloys 3) alloyed to Boron, and 4) martensitic stainless steel. The evaluation was made from accelerated erosion tests (ASTM G76), OM, SEM and Vickers micro hardness tests. It was found that the behavior of coatings containing large amounts of defects, mainly porosity, when exposed to accelerated wearing in a temperature of 370 °C showed a higher wear rate than the ASTM A178 and that the best performance among the alloys sprayed was the stainless steel AISI 420, which showed about 2% of porosity and a material removal mechanism predominantly ductile.
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Fouque, Aurélien. "Contribution à l'étude du couplage thermique-mécanique-électrique dans les contacts électriques : application à l'élaboration d'un modèle de durée de vie d'un contacteur." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC001.
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Un contacteur est un dispositif électromécanique destiné à établir ou couper un courantélectrique dans un circuit par la fermeture ou l’ouverture de contacts. Lors de chaquemanœuvre, un arc électrique est créé entre les «pastilles» des contacts, conduisant parl’énorme densité de puissance mise en jeu à atteindre et dépasser localement la températurede fusion du matériau. De ce fait, l’action répétée des arcs durant la vie de l’appareil (jusqu’àplusieurs centaines de milliers de cycles ouverture/fermeture) mène progressivement à la«ruine» des pastilles des contacts et au dysfonctionnement du contacteur. Le travail de thèsevise à proposer des outils de modélisation de l’endommagement des pastilles de contact sousl’effet des arcs, dans l’objectif à plus long terme de prédire la durée de vie du contacteurselon ses conditions d’utilisation. Le matériau considéré est un pseudo-alliage en argent etoxyde d’étain. Dans un premier temps, plusieurs campagnes expérimentales ont été menéespour réunir toutes les données d’entrée indispensables aux modélisations : déterminationdes propriétés thermomécaniques du matériau, caractérisation des endommagements – ensurface et en profondeur – produits par un arc unique et par une accumulation d’arcs,estimation de la densité de puissance apportée par un arc au matériau de contact. Denombreuses techniques ont ainsi été mises en œuvre : essais de traction monotone et dechargement cyclique, indentation (microdureté), profilométrie 3D, microscopies optiqueet électronique à balayage, analyses EDS et EBSD, imagerie par caméras thermique etultrarapide. Puis deux types de modèles ont été successivement développés. Le premierutilise le code de calcul par éléments finis Zset. Développé en géométrie axisymétrique, ilvise à décrire au sein du matériau l’évolution des températures, contraintes et déformationsrésultant d’un arc (supposé fixe), puis l’amorçage de fissures au terme de quelques centainesd’impacts au même point. Une variante 3D a ensuite été abordée pour approcher le casd’arcs mobiles. Le second modèle, de nature phénoménologique, repose sur des descriptionssimplifiées de la topographie et de la teneur en argent au voisinage de la surface, ainsique sur des règles d’occurrence et de distribution spatiale, issues autant que possible desobservations expérimentales. Il est destiné à simuler dans un temps de calcul raisonnableles dommages résultant du cumul d’un très grand nombre d’arcs sur toute la surface despastillesA contactor is an electromechanical device designed to establish or disconnect anelectrical current in a circuit by closing or opening contacts. During each operation, anelectric arc is created, due to the enormous power density involved to reach and locallyexceed the melting temperature of the material. As a result, the repeated action of thearcs during the life of the device (up to several hundred thousand closing/opening cycles)gradually leads to the ruin of the contact pads and the malfunction of the contactor. Thethesis work aims to propose tools for modelling the damage of contact pads under the effectof repeated impacts, with the longer-term objective of predicting the life of the contactoraccording to its operating conditions. The material considered is a pseudo-alloy made ofsilver and tin oxide SnO 2 . As a first step, several experimental campaigns were carried outto collect all the input data required for modelling : determination of the thermomechanicalproperties of the material, characterization of damage – surface and bulk – produced by asingle arc and by an accumulation of arcs, estimation of the power density provided by anarc to the contact material. Many experimental techniques have been used : monotonoustensile tests and cyclic loading, indentation (microhardness), 3D profilometry, opticalmicroscopy and scanning electron microscopy, EDS and EBSD analysis, thermal imagingcamera, high speed camera. Then two types of models were successively developed. Thefirst one uses the Zset finite element code. Developped in an axisymmetric geometry, itaims to describe within the material the evolution of temperatures, stresses and strainsresulting from an arc (assumed fixed), then the initiation of cracks after a few hundredof impacts at the same point. A 3D variant was then discussed to approach the case ofmoving arcs. The second model, of a phenomenological nature, is based on simplifieddescriptions of topography and tensile strength in silver in the vicinity of the surface, aswell as on rules of occurrence and spatial distribution, taken as much as possible fromexperimental observations. It is intended to simulate in a manageable calculation time thedamage resulting from the accumulation of a very large number of arcs over the entiresurface of the pellets
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Saillard, Marianne. "Dynamique du soulèvement côtier pléistocène des Andes centrales : étude de l'évolution géomorphologique et datations (10Be) de séquences de terrasses marines (Sud Pérou - Nord Chili)." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/431/.
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L'étude géomorphologique et la datation de séquences de terrasses marines, le long de la côte des Andes centrales, a permis de mettre en évidence une variabilité longitudinale et temporelle de la réponse de la plaque sud-américaine à la subduction de la plaque Nazca, au cours du Pléistocène. Les vitesses de soulèvement moyennes, déduites des âges 10Be, varient de 229 ± 40 (17,8°S) à 696 ± 53 mm/ka (15,33°S) le long de la côte. Des périodes de soulèvement rapide alternent avec des périodes de soulèvement plus lent au cours du Pléistocène. L'évolution morphologique de l'avant-arc est contrôlée par des processus tectoniques actifs liés à la zone de subduction. En-dessous d'une valeur seuil de 100-110 km de distance fosse-continent, les terrasses marines sont préservées et enregistrent les plus forts taux de soulèvement de la côte. Le soulèvement épisodique résulterait d'une variation de la surface de la zone sismogénique au cours du Pléistocène, en relation avec la variation de la distance fosse-continentGeomorphic study and dating of marine terrace sequences along the coastal part of the Central Andean forearc evidence longitudinal and temporal variations in the response of the South American plate to the Nazca plate subduction during Pleistocene. The average uplift rates vary between 229 ± 40 (17. 8°S) and 696 ± 53 mm/ka (15. 33°S) along the coast. Rapid uplift periods alternate with slower uplift during the Pleistocene times. The morphologic evolution of the forearc is directly linked to active tectonic processes occurring along the subduction zone. Below a threshold in the continent-trench distance of about 100-110 km, the marine terraces are preserved and record the highest uplift rates of the whole Andean coastal front. The episodic uplift would be a result of the seismogenic zone surface variations during the Pleistocene and the related variation in the continent-trench distance
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Li, Yung-Yuan, and 李永元. "Inverse Analysis of Transient Heat Source from Arc Erosion." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/28824641948583198421.
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碩士國立中山大學
機械工程學系研究所
89
An inverse method is developed to analyze the transient heat source from arc erosion. The temperature at the contour of arc erosion is assumed as melting point. And the temperature in grid points at the last time is calculated by interpolation, which include measurement errors. Then, the unknown parameters of transient heat source can be solved by linear least-squares error method. These parameters are plasma radius at the anode surface grows with time, arc power, and plasma flushing efficiency on the anode. Because the temperature in measuring points includes measurement errors, the exact solution can be found when fewer unknowns are considered. The inverse method is sensitivity to measurement errors.
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Chen, Jiun-Ming, and 陳俊名. "Erosion Behavior of Gas Tungsten Arc Welded TiNi Intermetallic Overlay." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/5y2k6h.
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碩士逢甲大學
材料科學所
90
The pseudoelasticity of TiNi intermetallic alloy provides excellent fatigue resistance and cavitation erosion resistance. A variety of surface engineering processes have been proposed using TiNi coating to reduce damage of erosion. It may be a good idea that using the hardfacing process to yield TiNi intermetallic overlay to protect the commonly used materials with a low cost. Gas tungsten arc welding (GTAW) was chosen to yield an overlay by using Ti50Ni50 intermetallic onto SUS 304 stainless steel and JIS S45C medium carbon steel, and structure of TiNi overlay is manipulated by welding current. Solid/gas impingement and cavitation in different solutions were carried out to explore the erosion behavior of the overlay. Experimental results show that using higher current (130 A) produces a larger heat input and residual stress to make the as-welded TiNi overlay on SUS 304 cracked. Because of this, a proper welding current 85A was determined and microstructure of the weld overlay was characterized. It shows a common as-welded dendrite structure. The X-ray diffraction pattern shows that the as-welded overlay on SUS 304 was approximately TiNi-B2, TiNi-B19’, TiNi3 and Ti3Ni4 phases, while it was TiNi-B2 and TiNi3 phase on S45C. Solid particle impact test was carried out to explore the erosion behavior of the overlay. Substrates and TiNi overlays impacted at 45 m/s shows that all the overlay mass loss were higher than bare substrates at any impact angle indicating a poorer resistance to erosion damage, due to the composition of TiNi overlay was changed lead to lose the behavior of pseudoelasticity, and the dendrite structure. TiNi overlay’s erosion rate was increased with increasing impact angle revealing that the TiNi overlay presents a behavior of brittle material. The XRD diffraction patterns after erosion test suggest a lattice distortion without any phase change by the so called pseudoelasticity. A post heat treatment for the TiNi overlay can reduce internal stress and increase toughness to improve the TiNi overlay erosion resistance. This, however, is helpless to eliminate dendrite structure. Cavitation resistance was evaluated using the ASTM G32-92 standard test in fresh water, 3.5 wt% NaCl water solution and 3.5 wt% HCl water solution. Experimental results show that TiNi overlay in the three solutions significantly increase cavitation resistance. Again, the overlay XRD diffraction patterns after cavitation test suggest a lattice distortion without any phase change. The excellent cavitation resistance due primarily to the higher hardness of the overlay itself. The DC polarization behaviors of TiNi overlay were measured to explore the electrochemical behavior in corrosion environments. It shows that the TiNi overlay in both 3.5 wt% NaCl solution and 3.5 wt% HCl solution exhibit higher corrosion potential and lower corrosion current than the bare substrates. This brings a positive effect to the cavitation resistance.
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Chung, Ho-Hua, and 鐘鶴崋. "Fundamental Studies on Arc Characteristics and Erosion Mechanism of Electrical Contacts." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/66473673998789362866.
Full textAbstract:
博士國立中山大學
機械與機電工程學系研究所
91
Abstract The arc behavior during the closing and opening of electrical contacts not only influences the surface morphology, but also causes the erosion of contact material. The mechanical stresses, the molten bridge, and the arc cause this erosion. Consequently, the erosion mechanism is very complex. Therefore, to avoid the influences of mechanical stresses and numerous arc striking, static-gap experiments with a single arc discharge are conducted to investigate the effects of pulse voltage, gap distance, and arc duration on the erosion characteristics and mechanism of silver based contact materials. Moreover, this experimental result is verified by the finding of the dynamic testing of electrical contacts. The results of the erosion characteristics show that the arcing and non-arcing regions have been distinguished at the supply voltage from 32 V to 500 V and the gap distance from 0.2 mm to 40 mm. The empirical formula for the minimum pulse voltage at arc initiation in terms of gap distance is established. When the pulse voltage is smaller than 200 V, the erosion area increases with increasing gap distance due to the action of the metallic-phase arc. However, when the pulse voltage is greater than 200 V, with increasing gap distance, the erosion area increases to a maxim, and finally diminishes due to the increase in the amount of gaseous-phase arc. The results of the erosion mechanism show that the arcing region is classified into three erosion patterns, namely, the molten metal bridge (B), metallic-phase arc (M), and gaseous-phase arc (G). At the gap distance of 0.2 mm, the erosion pattern of anode silver is varied from B, through B+M, and, M, to M+G. According to the electron transfer across triangular potential barrier, the thermionic emission causes the erosion patterns of B, B+M, and M, and mixed thermionic and field emission results in the erosion pattern of M+G. When the pulse voltage is 500 V, with increasing gap distance, the splashing of metallic particles around the anode crater becomes more dispersed, shorter with more silver powder, and finally disappeared with a little silver powder due to the influence of the gaseous-phase arc. The results of the anti-weld ability show that when the pulse voltage is 500 V and the arc energy is grater than 14 J at the static-gap experiments, the critical gap distance to produce welding for Ag-Ni, Ag-CdO, and Ag-SnO2 is 3 mm, 8 mm, and 15 mm, respectively. This indicates Ag-Ni contact possesses the best anti-weld ability. On the other hand, the results of dynamic testing of electrical contacts show that at the arc energy less than 10 J, the anti-erosion, anti-weld ability, and the welding area are seen to increase with contact materials in the following order: Ag-CdO > Ag-SnO2 > Ag-Ni. However, when the arc energy is greater than 10 J, the anti-erosion, anti-weld ability, and the erosion area are seen to increase in the reverse order: Ag-SnO2 < Ag-CdO < Ag-Ni, which are in very good agreement with the results of static-gap experiments. Furthermore, the erosion surface of the silver-based contact materials can be observed and analyzed by using the X-ray diffraction method (XRD), differential thermal analysis (DTA), and gravitation thermal analyzer (GTA). Results show that when the arc energy is greater than 14 J, Ag-CdO and Ag-SnO2 have been decomposed into Ag-Cd and Ag-Sn alloys, respectively, which reduce their anti-weld ability. On the other hand, the welding trend has been reduced due to the dispersion of NiO on the surface of Ag-Ni contact. Consequently, the anti-erosion and anti-weld ability for the Ag-Ni contacts are better than those of the other Ag-MeO contact materials.
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Singh, Gurjit, Henning Schuster, and Uwe Füssel. "The erosion behaviour of pure tungsten electrodes in Gas Tungsten Arc Welding (GTAW)." 2019. https://tud.qucosa.de/id/qucosa%3A38633.
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A cross-time study has been made on the erosion behaviour of Gas-Tungsten Arc Welding (GTAW) for pure tungsten electrode. Its behaviour during arcing was analyzed and compared from the points of view of metallurgical changes in electrode due to long-term operation. Metallographic studies of the electrodes indicate that the crack formation and grain growth during periodic temperature variations. These observations are discussed theoretically based on the experimental results and the thermal expansion parameters of Tungsten.
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Chang, JingTang, and 張景棠. "Cavitation Erosion Behavior of TiNi Thin Films Deposited by Cathodic Arc Plasma Ion Plating." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/55860173335944425053.
Full textAbstract:
碩士逢甲大學
材料科學學系
88
TiNi intermetallic compound is considered for its pseudoelasticity to the application of cavitation resistance. It is however expensive and motivated the introduction of thin film process. Cathodic arc plasma deposition was used to deposit TiNi films on S48C medium carbon steel substrate. The substrates bias voltage was changed to optimize the properties of the deposited film when using Ti50Ni50 target. And Ti55Ni45 and Ti60Ni40 targets were used as well to deposit different film compositions. Surface and cross-sectional morphology of the deposited films were observed by using scanning electron microscopy. Film microstructure was characterized using XRD. EDS was used to analyze the elemental constituents of the deposited films. Cavitation resistance of the deposited films was evaluated using the ASTM G32-85 standard test in fresh water, 3.5wt% NaCl water solution and 3.5wt% HCl water solution. The DC polarization behaviors of films were measured to explore the electrochemical behavior of coated specimens in corrosive environments. Experimental results show that films deposited by using target Ti50Ni50 is Ti45Ni55. The major phase in such films is TiNi-B2, TiNi3 and TiNi-B19’ coexist as the minor phase. The film compositions were Ti49Ni51 and Ti51Ni49 when target composition Ti55Ni45 and Ti60Ni40 were used. The major phase in films deposited by using Ti55Ni45 target is TiNi-B2 accompanied with TiNi3 and TiNi-B19’. The major phase in films deposited by using Ti60Ni40 target is TiNi-B2 accompanied with TiNi-B19’ and Ti2Ni, without TiNi3. Crystallinity increases with increasing titanium composition. Cavitation resistance of specimens was significantly increased to more than a 3-fold value in comparison with the uncoated carbon steel in fresh water if high substrate bias voltage was applied. These promising results suggest that cathodic arc plasma ion plating is suitable for preparing cavitation resistant TiNi films, if high substrate bias voltage is employed. In the case of 3.5wt% NaCl solution and 3.5wt% HCl solution, the cavitation weight loss of specimen is higher than the specimen in fresh water. In fresh water, the films with different compositions almost have the same weight loss. Film composition does not influence the cavitation resistance of films in this regard. It however causes the difference in weight loss of specimens by suffering the electrochemical reactions that occurs in NaCl solution and HCl solution. Titanium-rich film composition may reduce Icorr and give rise to Epp of specimens in 3.5wt% NaCl solution, or reduce Icorr of specimens in 3.5wt% HCl solution. This explains that the films prepared by using Ti60Ni40 and Ti55Ni45 target have superior cavitation resistance.
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Huang, Hsu-Ming, and 黃旭明. "Study on the Mechanism of Arc and Erosion of Silver Contacts in Direct Current." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/66831791381232545824.
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碩士國立中山大學
機械工程研究所
83
In this study, the arc phenomenon and erosion mechanism are investigated by using the DC switching tester for silver contacts during making and breaking period. Experimental results show that the arc length remains in a fix range at different breaking speeds under the same voltage and current conditions during breaking period. According to the result of material transfer, the erosion mechanism can be classified into the following four forms: I. Material is transferred from anode to cathode. II. Material is transferred from cathode to anode. III. The direction of material transfer is unstable. IV. Both poles loss. It is found that anode must be the best to obtain the longer life for convex profile in form I and cathode must be the best to obtain the longer life for convex profile in form II. The contacts can maintain the longer life in form III. The amounts of material transfer increase from anode to cathode with increasing current at low voltage below 10V. Material is transferred from cathode to anode at the higher voltage of 20-50V and the low current, but it would change the direction of material transfer when the current increases to a certain amount at the same voltage.
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Gao, Jian-ming, and 高健銘. "Erosion Characteristics of the Composite Electroplated Layer of Nickel-Diamond Powder under Static Single-Arc Discharge." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/79026346476891517555.
Full textAbstract:
碩士國立中山大學
機械與機電工程學系研究所
92
Diamond has superior characteristics, such as high hardness, high isolation, and high breakdown voltage, but it is also difficult to manufacture for industrial application. Because diamond is a nonconductor, the usual electrical discharge machining (EDM) method cannot be used. Hence, this study uses the plating nickel to keep the diamond powder as the composite electroplated layer of nickel-diamond powder. The variation of the composite layer and the diamond particle erosion characteristic after arc discharge can be realized by single-arc discharge. By the result of experiment, it can be known that the erosion area will be enlarged when the diamond particle is near to central erosion area, because the diamond that has good heat stability makes plasma to spread. The erosion area will be decreased when the diamond particle is near to edge of erosion area, because it stops the melted nickel to spread. The surface of diamond particle is broken slightly that the particle become more spherical and has some nickel remain on it when pulse voltage is less than 300 volt or the diamond particle is near to edge of erosion area. The surface of diamond particle is broken seriously that the particle is cracked to pieces when pulse voltage is more than 300 volt or the diamond particle is near to central erosion area.
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Jau, Chi-Shen, and 趙啟盛. "Study on Electric-Arc Characteristics and Formation Mechanism of Erosion for DC Silver Contacts in Inert Gas." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/50002716603082624203.
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碩士國立中山大學
機械與機電工程學系研究所
90
Abstract In this study, a static electric contact tester with a vacuum system and gas supply system is used to investigate the effects of experimental parameters, such as inert gas kind, supply voltage, and the gap between the contacts, on the electric-arc characteristics and the erosion type for the electric contacts of silver. The experimental results show that chargeable threshold voltage in helium is higher than that in argon or air. In addition, the erosion surface of anode is observed, and the erosion area and volume are calculated and analyzed. Results show that the erosion area and volume in helium are smaller than that in argon or air. According to the observation of SEM photomicrographs, metal sputtering of the erosion hole in helium is smaller than that in argon or air. It is expected to provide the domestic electrical contact manufacturer in improving the research and development technique of the electrical contacts, and the design reference related to ultra-precision machining using a clean room.
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Dai, Wen-Shyong, and 戴文雄. "A Study on the Plasma-Transferred-Arc Surface Modification and Silica Sand Erosion of Graphite Cast Irons." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/60430177688007528559.
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博士國立成功大學
材料科學及工程學系
88
The mechanical properties of flake graphite and spheroidal graphite cast irons are influenced by graphite distributions and matrix structures. These two metallurgical factors were used as important variables for discussing the erosion behavior of graphite cast irons in this study. Besides, in order to realize the surface modification effects on the erosion resistance, plasma transferred arc (PTA) process was used to remelt the surfaces of graphite cast irons. The remelted surface layers of different solidification structures were obtained by varying the PTA processing parameters, the matrix structures and compositions (e.g., carbon and silicon) of the graphite cast irons. In the erosion experiment, SiO2 particles of ~295mm size were used as the erodent. The impact angle varied from 150 to 900 with the average particle velocity ~66m/s and ~36m/s. The results indicate that with the same graphite morphology and distribution, martensitic matrix results in less wear loss than ferritic matrix when eroded under oblique impact; the situation is reversed under large-angle impact. Under the same test condition, spheroidal graphite leads to better erosion resistance than flaky graphite. In addition, types A and D flake graphite cast irons will cause cracks to occur from graphite tips at higher impact angles; brittleness effect of hard martensitic flaky graphite will become more obvious with increasing impact angle. The spheroidal graphite cast iron with ferritic matrix have no brittle wear loss and thus have the maximum erosion rate at ~300 impact. Ferritic flake graphite cast iron and martensitic spheroidal graphite cast iron result in both ductile and brittle erosion mechanisms, and thus have the maximum erosion rate at ~550 to ~750 impact. Martensitic flake cast irons show brittle erosion as the governing mechanism and hence have the maximum erosion rate at ~900 impact. PTA remelting of the graphite cast irons result in rapid solidified layers of 2~5mm thick. The eutectic cementite in the remelted layers has strong hardening effect. To decrease the remelting heat input, increase the carbon content of substrate, decrease the silicon content of substrate or coarsen the distribution of graphite, the volume fraction of eutectic cementite will increase and graphite will decrease in remelted layer and thus the hardness will rise. The experiment indicates that the eutectic cementite is more erosion-resistant when eroded at oblique impact, while it will easily result in brittleness at large-angle impact. For the flake graphite cast irons, PTA remelting process can reduce the distribution of network graphite on original material and thus decrease the wear loss effect of graphite morphologies. Therefore, the overall erosion resistance can be improved and the gradual improvement increases with nodule graphite morphologies. Erosion of remelted layer of flake graphite cast irons is mainly affected by eutectic cementite and graphite distribution and hence has the maximum erosion rate at ~500 impact. As to the spheroidal graphite cast irons, for the graphite still shows nodule morphologies on remelted layer, its erosion behavior is governed by eutectic cementite. The better erosion resistance of eutectic cementite under oblique impact leads to the result that the wear loss of the PTA remelted layer is less than that of the unremelted substrate under oblique impact. When the spheroidal graphite cast irons are eroded under large-angle impact, brittle cracking is easily found on eutectic cementite and thus the wear loss of remelted layer will be affected by its existence. Brittleness effect of eutectic cementite will cause the impact angle of maximum erosion rate to increases from ~450 with its volume content. Though the unremelted spheroidal graphite cast irons possess good erosion resistance under large-angle impact, this experimental results also indicate that as long as the volume fraction of eutectic cementite on the modified layer and the particle velocity are controlled properly, the brittleness effect of the remelted layer can be reduced and thus the erosion resistance under large-angle impact can be raised even to a level better than the original substrate. When remelted under lower heat input (120A current), the PTA remelted solidification structure of the flake graphite and spheroidal graphite cast irons are similar (especially, the graphite being nodular in morphology). Consequently, they show less difference in erosion resistance. When the heat input is higher (*160A), the graphite on the remelted layer of flake graphite cast iron appear flaky distribution and thus the wear loss of is increased. Therefore, its erosion resistance is obviously worse than that of the surface remelted spheroidal graphite cast iron.
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Chen, Yu-Dung, and 陳宇東. "Study on erosion wear and corrosion behaviors of Cr-N-O duplex coatings by cathodic arc deposition system." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/02753017661714352328.
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碩士大同大學
材料工程學系(所)
94
Cathodic arc deposition (CAD) process is one of physical vapor deposition. Due to the advantages of high ion rate, more ions and high ion energy, the coatings own better adhesion, high density, high homogeneity, broader coating condition, lower substrate temperature and keeping homogeneity with target, the hard ceramic films coated on steel by CAD can improve its lifetime effectively. CrN is easy to change to dense Cr2O3, so CrN have these properties, included high hardness, oxidation resistance at high temperature, low friction, corrosion and wear resistance. In some application, the hardness of CrN is lower than TiN or TiAlN, but its oxidation and wear resistance is better than both. Based on the relationship between CrN and Cr2O3, Cr(N,O)/CrN duplex films were coated by CAD by controlling the ratio of nitrogen and oxygen flow. A series of mechanical property measurement and analysis was deformed. As shown in the experiment, the content of chromium of droplets is higher than the Cr2O3 coating. From EPMA and XPS analysis, the Cr(N,O)/CrN coatings included other compounds, ex: CrO3,Cr2N….etc, beside CrN and Cr2O3 known by XRD. Due to Cr2O3 have the higher residual compression stress, the Cr(N,O)/CrN coating was insufficient and affected the resistance erosion, but it had higher hardness and elastic modulus and lower friction. In the corrosion test, duplex coatings is superior to single coating.
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Hu, Edwin, and 胡恩德. "Investigation on the Electric-Arc Characteristics and the Formation Mechanism of Erosion for DC Silver Contacts in Vacuum." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/75761025085112304866.
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碩士國立中山大學
機械工程學系研究所
89
In this research, a static electric contact tester with a vacuum system is used to inverstigate the efedts of experimental parameters, such as air pressure, input voltage and current, contact material, and the gap between the contacts, on the electric-arc characteristics and the erosion debris type for the electric contacts of silver (Ag). The experiments are conducted under various experiment parameters, and the erosion debris is collected. After each experiment, the erosion debris will be calculated and observed to investigate the difference between erosion particles under various experiment conditions. Moreover, according to the results of the metallic phase and gaseous phase arc duration and the erosion particle type under various air pressures and the gaps, the electric-arc criterion and the erosion mechanism of DC electrical contacts will be established to provide the domestic electrical contact manufacture in improving the research and development technique of electrical contacts, and the design reference of super precision environment—clean room
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Gabriel, Brian M. Wolfe Douglas E. "Synthesis-structure-property-performance relationships of tin, CrN, and nanolayer (Ti,Cr)N coatings deposited by cathodic arc evaporation for hard particle erosion resistance." 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-3477/index.html.
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Ondáč, Peter. "Experimentální zkoumání anodové oblasti hybridního plazmového hořáku s vodně-plynnou stabilizací DC oblouku." Doctoral thesis, 2020. http://www.nusl.cz/ntk/nusl-411461.
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This thesis focuses on an experimental study of the anode area of the hybrid water- gas DC arc plasma torch that is used in many industrial applications, including plasma spraying, hydrocarbon reforming, pyrolysis, and organic waste gasification. The effects of ambient pressure and plasma generation conditions on the torch's plasma jet were studied, with particular focus on the torch's anode area. Movement of the anode arc attachment is described in detail, including its speed, range of its motion on the anode surface, restrike periods, and the frequency of its many sudden decelerations and re-accelerations. It was found that the anode erosion can be compared relatively simply by quick processing of high-speed camera videos. The anode erosion was also measured directly. Many electric probe measurements were made in the anode area of this plasma torch for the first time. By using these electric probes, shock waves, turbulent vortices, and plasma potential fluctuations were studied directly. It was found that a mean plasma electric field and a mean plasma electrical conductivity in the anode area can be satisfactorily estimated also non-intrusively by quick processing of high-speed camera videos. Moreover, schlieren videos of the plasma jet in the anode area were created. 1