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1
Persson, Daniel H. E. "On the Mechanisms behind the Tribological Performance of Stellites." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6201.
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Werry, Arnaud. "Développement de matériaux multi échelles anti usure et anticorrosion pour remplacement des stellites en milieu nucléaire." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0111/document.
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Le remplacement des Stellites, un superalliage base cobalt, en milieu nucléaire dans certaines parties du réacteur en milieu primaire a été étudié depuis les années soixante. Plusieurs nuances de revêtements base Fer et Nickel, sans ou avec très peu de cobalt, ont été développées dans ce sens. La quatrième génération de centrale impose également des conditions de fonctionnement très sévère pour les revêtements durs. L’idée principale de ce travail de thèse est de renforcer des nuances commerciales de superalliages base nickel avec des particules micrométriques et sub-micrométriques d’alumine par plasma d’arc transféré, Cold Spray et coprojection plasma simultanée de poudre et de suspension.Pour les dépôts PTA, l’analyse des dépôts a montré un raffinement de la microstructure mais une répartition inhomogène de l’alumine. L’ajout d’alumine n’a pas influé sur la microdureté des dépôts mais a permis d’améliorer la résistance à l’usure abrasive sous air. Les dépôts obtenus par projection plasma, en combinant projection classique de poudre et de suspension d’alumine, ont montrés un meilleur comportement tribologique sous conditions particulières. Les effets de l’ajout d’alumine dans la matrice ont été étudiés en observant la microstructure et en comparant les propriétés mécaniques des dépôts (micro dureté, et tests tribologiques représentatifs de l’application) pour différents taux de renforts (de 0 à 13% pds)In nuclear plants, the replacement of hardfacing Stellite, a cobalt-base alloy, on parts of the piping system in connection with the reactor has been investigated since the late 60’s. Various Fe-base or Ni-base alloys, Co-free or with a low content of Co, have been developed in this aim. The 4th generation nuclear plants impose additional or more stringent requirements for hardfacing materials. The idea developed in this work is to reinforce commercial nickel base alloy with addition of micrometric and sub-micrometric alumina particles by Plasma Transferred Arc welding, Cold Spray and simultaneous conventional and suspension plasma spray.For PTA Coatings, the examination of coatings revealed a refinement of the microstructure but an inhomogeneous alumina distribution. The addition of alumina particles did not improve the micro-hardness of coatings but improve their resistance to ambient air abrasive wear.The coatings prepared by plasma spraying, combining powder of metallic matrix and suspension of ceramic particles, showed better tribological performance under particular conditions. The effect of the addition of ceramic particles in the matrix was investigated by observing the microstructure of coatings, and comparing their mechanical behavior (micro hardness and tribological tests representative of the application) for different ceramic particle contents (from 0 to 13 wt%)
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Daumer, Tomáš. "Navařování Stellitem na ocel 1.4122." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254458.
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Master‘s thesis describes issues of stainless steel welding. The analysis carries out the stainless steel‘s state of art in term of welding, chemical composition, physical and mechanical properties. Experimet is based on cladding of Stellite alloys to martensitic stainless steel X39CrMo17-1. The practical part describes the used devices and carries out evaluation of specifically designed heat input, macrostructure and hardness.
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Yu, Hao. "The microstructure and tribo-mechanical properties of HIPed stellite alloys." Thesis, Heriot-Watt University, 2007. http://hdl.handle.net/10399/2159.
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Gehring, Junior Waldemar [UNESP]. "Desempenho do stellite como material de ferramenta no serramento da madeira." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/94387.
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O presente trabalho apresenta uma análise de parâmetros para a seleção de material de ferramenta de corte indicando o uso do Stellite como alternativa para obter melhor produtividade nas serrarias de desdobro de madeiras no Brasil. Para tanto, estudou-se as inter relações entre a propriedades físico químicas de espécies de madeira tropical e o processamento mecânico de desdobro das mesmas, além das origens do desgaste dos materiais empregados como ferramenta de corte. Foram realizados experimentos para determinar as características de densidade básica, teor de sílica e acidez de algumas espécies de madeira tropicais. As espécies estudadas foram: Angelim vermelho (Dinizia excelsa Ducke), Angelim pedra (Hymenolobium petraeum Ducke), Maçaranduba (Manilkara huberi (Ducke) Chevalier), Itaúba (Mezilourus lindaviana Schwacke & Mez), Mandioqueira lisa (Qualea albifloraWarm), Mandioqueira escamosa (Qualea paraensis Ducke) e Quaruba fissurada (Vochysia maxima Ducke). Para tais experimentos, as amostras foram colhidas e gerenciadas nas regras do manejo sustentável. Após a caracterização das espécies e análise do grau de abrasividade das mesmas, foi escolhida a espécie Maçaanduba para os testes de desempenho em processos de usinagem e, nas condições de corte e processamento utilizadas, relata-se de forma comparativa os apectos teóricos citados na revisão bibliográfica. Como resultado, pode-se comprovar que o material Stellite apresentou desempenho superior relativo ao desgaste e avarias, quando comparado com outros materiais como o metal duro, além de demonstrar um efetivo ganho de produtividade no serramento de toras de madeira de maçaranduba
This study presents an analysis of selection parameters for cutting tool materials, indicating Stellite alloy as a substitute to improve sawmill productivity in Brazil. For that purpose, it was studied the interrelationship between the physical and chemical properties of tropical wood and the wood cutting mechanical process, as well as the origins of wear in cutting tool materials. Some tropical woods were tested for specific, gravity, silica content and acidity. The following species were studied: Angeli vermelho (Dinizia excelsa Ducke), Angelim pedra (Hymenobolobium petraeum Ducke), Maçaranduba (Manilkara huberi (Ducke) Chevalier), Itaúba (Mezilaurus lindaviana Schwacke & Mez), Mandioqueira lisa (Qualea albiflora Warm), Mandioqueira escamosa (Qualea paraensis Ducke) e Quaruba fissurada (Vochysia maxima Ducke). For those experiments, the samples were collected and processed following sustainable management practices. After characterization and analysis of abrasion degree of those species, the Manilkara huberi (Ducke) Chevalier was selcted for the machining process performance tests. Under the cutting and processing conditions established, the theoretical aspects cited in the references are comparatively reported. As a result, it was possible to demonstrate that the Stellite alloy displayed better wear and tear perfomance when compared with other materials sucha as hard beside demonstrating effective productivity gain when sawing Manilkara huberi (Maçaranduba) wood
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Gehring, Junior Waldemar. "Desempenho do stellite como material de ferramenta no serramento da madeira /." Guaratinguetá : [s.n.], 2011. http://hdl.handle.net/11449/94387.
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Orientador: Marcos Tadeu Tibúrcio GonçalvesBanca: Manoel Cleber de Sampaio Alves
Banca: Ivaldo de Domenico Valarelli
Resumo: O presente trabalho apresenta uma análise de parâmetros para a seleção de material de ferramenta de corte indicando o uso do Stellite como alternativa para obter melhor produtividade nas serrarias de desdobro de madeiras no Brasil. Para tanto, estudou-se as inter relações entre a propriedades físico químicas de espécies de madeira tropical e o processamento mecânico de desdobro das mesmas, além das origens do desgaste dos materiais empregados como ferramenta de corte. Foram realizados experimentos para determinar as características de densidade básica, teor de sílica e acidez de algumas espécies de madeira tropicais. As espécies estudadas foram: Angelim vermelho (Dinizia excelsa Ducke), Angelim pedra (Hymenolobium petraeum Ducke), Maçaranduba (Manilkara huberi (Ducke) Chevalier), Itaúba (Mezilourus lindaviana Schwacke & Mez), Mandioqueira lisa (Qualea albifloraWarm), Mandioqueira escamosa (Qualea paraensis Ducke) e Quaruba fissurada (Vochysia maxima Ducke). Para tais experimentos, as amostras foram colhidas e gerenciadas nas regras do manejo sustentável. Após a caracterização das espécies e análise do grau de abrasividade das mesmas, foi escolhida a espécie "Maçaanduba" para os testes de desempenho em processos de usinagem e, nas condições de corte e processamento utilizadas, relata-se de forma comparativa os apectos teóricos citados na revisão bibliográfica. Como resultado, pode-se comprovar que o material Stellite apresentou desempenho superior relativo ao desgaste e avarias, quando comparado com outros materiais como o metal duro, além de demonstrar um efetivo ganho de produtividade no serramento de toras de madeira de maçaranduba
Abstract: This study presents an analysis of selection parameters for cutting tool materials, indicating Stellite alloy as a substitute to improve sawmill productivity in Brazil. For that purpose, it was studied the interrelationship between the physical and chemical properties of tropical wood and the wood cutting mechanical process, as well as the origins of wear in cutting tool materials. Some tropical woods were tested for specific, gravity, silica content and acidity. The following species were studied: Angeli vermelho (Dinizia excelsa Ducke), Angelim pedra (Hymenobolobium petraeum Ducke), Maçaranduba (Manilkara huberi (Ducke) Chevalier), Itaúba (Mezilaurus lindaviana Schwacke & Mez), Mandioqueira lisa (Qualea albiflora Warm), Mandioqueira escamosa (Qualea paraensis Ducke) e Quaruba fissurada (Vochysia maxima Ducke). For those experiments, the samples were collected and processed following sustainable management practices. After characterization and analysis of abrasion degree of those species, the Manilkara huberi (Ducke) Chevalier was selcted for the machining process performance tests. Under the cutting and processing conditions established, the theoretical aspects cited in the references are comparatively reported. As a result, it was possible to demonstrate that the Stellite alloy displayed better wear and tear perfomance when compared with other materials sucha as hard beside demonstrating effective productivity gain when sawing Manilkara huberi (Maçaranduba) wood
Mestre
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Ohlsson, Daniel. "Kartläggning av ventiler innehållande Stellite i reaktornära vattensystem på Forsmark 2." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-25130.
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In the process of a boiling water reactor, high-levels of waste and radiation occur, where almost all the dose per person of the radiation in Forsmark are due to the radioactive iso-tope cobalt-60. The reason is that the stable isotope cobalt-59 is converted to the radioac-tive isotope cobalt-60 due to neutron irradiation in the reactor. Since 2012, unusually high levels of cobalt-60 have been observed at Forsmark 2 which occurs from the material Stel-lite and is a very common sealant in valves. The major disadvantage of the material Stellite in nuclear power is the high concentration of cobalt-59. When grinding alloy surfaces con-taining Stellite, cobalt-59 is released in the form of abrasive dust if the effectiveness of sub-sequent Stellite alloys is poor. The consequences lead to increased radiation levels, which implies major financial costs and a difficult work environment in, for example, mainte-nance work.Today, there is no mapping of valves containing Stellite, which may result in the decon-tamination of Stellite not being requested and missing when a maintenance action in the form of, for example, grinding is performed. The completed mapping of valves containing Stellite is thus the first that has been carried out within Forsmarks Kraftgrupp AB for the priority systems 313, 321, 331 and 415.In this work, valves containing Stellite have been mapped along main lines in systems that come into contact with reactor water without passing ion exchange filters. Furthermore, the effects of how the grinding of valves alloy surfaces in the seat / cone affects the feeding of cobalt-59 into the reactor and the effectiveness of subsequent decontamination of Stel-lite after grinding was investigated.The work has been divided into two main moments; Status analysis and Mapping, which in turn is divided into several sub-moments. The status analysis gathered the information re-quired to perform the mapping. With the gathered information from the status analysis, mapping was then carried out and valves were inventoried in the priority systems.A total of 45 valves containing Stellite were found whose water flow is likely to end up in the reactor without passing ion exchange filters. A total of 13 valves containing Stellite were found, which are not detected by the chemical departments measurement points and whose waterflow did not pass ion exchange filters before the reactor for systems 321 and 331.During a decontamination of Stellite in a valve, only alloy surfaces in the valves are con-trolled and cleaned, which results in dust from grinding remaining in the other surfaces of the valve as well as in the pipe ends when the valve has been assembled prior to commis-sioning. Of the 45 valves containing Stellite which have been inventoried, grinding in theseat/cone have occurred in eight of the valves, but only two of the valves have been de-contaminated since 2010-01-01. Since no decontamination of Stellite has occured six of eight times after grinding, and only alloy surfaces are checked as well as decontaminated, the effectiveness of subsequent decontamination of Stellite after grinding is very low.Based on the results of the work, a number of improvement proposals have been present-ed for continued work to reduce the feeding of cobalt 59 to the reactor water and eventu-ally reduce the radiation levels at Forsmark's nuclear power plant.Vid processen i en kokvattenreaktor uppstår högaktivt avfall och höga strålningsnivåer, där nästan all persondos av strålning på Forsmark beror av den radioaktiva isotopen kobolt-60. Anledningen är att den stabila isotopen kobolt-59 omvandlas till den radioaktiva isotopen kobolt-60 vid neutronbestrålning i reaktorn. Man har sedan 2012 noterat ovanligt höga halter av kobolt-60 på Forsmark 2 vilket härrör till materialet Stellite, som är ett mycket vanligt tätningsmaterial i ventiler. Den stora nackdelen med Stellite i kärnkraftssamman-hang är den höga koncentrationen av kobolt-59. Vid slipning av legeringsytor innehållande Stellite, riskeras kobolt-59 frigöras i form av slipdamm om effektiviteten av efterföljande Stellitesaneringar är dålig. Konsekvenserna leder till ökade strålningsnivåer vilket innebär stora ekonomiska kostnader och en försvårad arbetsmiljö vid till exempel underhållsar-beten.Idag finns ingen kartläggning av ventiler innehållande Stellite, vilket kan resultera i att Stellitesaneringar inte begärs och uteblir då en underhållsåtgärd i form av till exempel slipning utförs. Den genomförda kartläggningen av ventiler innehållande Stellite är där-med den första som har utförts inom Forsmarks Kraftgrupp AB för de prioriterade syste-men 313, 321, 331 och 415.I detta arbete har ventiler innehållande Stellite kartlagts längs huvudledningar i system som kommer i kontakt med reaktorvatten utan att passera jonbytarfilter. Vidare har effekterna av hur slipning av ventilers legeringsytor i säte/kägla påverkar inmatningen av kobolt-59 och effektiviteten av efterföljande Stellitesaneringar undersökts.Arbetet har delats upp i två huvudmoment; Nulägesanalys och Kartläggning, som i sin tur delats upp i flera delmoment. I nulägesanalysen samlades den information som krävdes för att utföra kartläggningen. Med den inhämtade informationen från nulägesanalysen, inven-terades och kartlades sedan ventiler i de prioriterade systemen.Totalt hittades 45 stycken ventiler innehållande Stellite vars vattenflöde riskerar att hamna i reaktorn utan att passera jonbytarfilter. Sammanlagt hittades 13 stycken ventiler innehål-lande Stellite som ej registreras av kemiavdelningens provtagningar och som inte passerar jonbytarfilter innan reaktorn för system 321 och 331.Vid en Stellitesanering kontrolleras och saneras endast legeringsytor i ventiler, vilket re-sulterar i att slipdamm kan finns kvar i ventilens övriga ytor samt i rörändarna då ventilen har monterats ihop inför driftsättning. Av de 45 stycken ventiler innehållande Stellite som har inventerats, har åtta stycken slipats i säte/kägla men enbart två stycken Stellitesanerats efter slipning sedan 2010-01-01. Eftersom Stellitesaneringar efter slipning har uteblivitsex av åtta gånger och endast legeringsytor kontrolleras samt Stellitesaneras, är effektivite-ten av efterföljande Stellitesaneringar vid slipning mycket låg.Baserat på resultaten av arbetet, har ett antal förbättringsförslag presenterats för fortsatt arbete att minska kobolt-59-inmatningen till reaktorvattnet och på sikt minska strål-ningsnivåerna på Forsmarks kärnkraftverk.
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DANTAS, David Valença. "A Utilização dos Diferentes Habitats do Estuário do Rio Goiana Pelas Diferentes Fases Ontogenéticas das Espécies Cathorops spixii, Cathorops agassizii, Stellifer brasiliensis e Stellifer stellifer (Actinopterygii, Teleostei). Estudo de Caso: Caracterização das Áreas Utilizadas Como Berçário." Universidade Federal de Pernambuco, 2012. https://repositorio.ufpe.br/handle/123456789/12162.
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CNPq
A utilização dos habitats está relacionada à variações na dieta ao longo do ciclo de vida. A análise da dieta das diferentes fases ontogenéticas em diferentes habitats pode gerar informações a respeito dos padrões de movimento entre os habitats utilizados como berçário e os dos adultos. O presente estudo descreve a utilização sazonal dos habitats e hábitos alimentares de diferentes fases ontogenéticas das espécies Cathorops spixii, Cathorops agassizii, Stellifer brasiliensis e Stellifer stellifer ao longo do canal principal do estuário do Rio Goiana. Neste estudo, foram utilizados dados referentes à amostragens realizadas com rede de arrasto no canal principal entre dezembro de 2005 e novembro de 2006. O canal principal do estuário foi dividido em três áreas (superior, intermediária e inferior), de acordo com o gradiente de salinidade e a geomorfologia do estuário. As espécies foram divididas em diferentes classes de tamanho, de acordo com o seu respectivo estágio de desenvolvimento, em jovens, sub-adultos e adultos. Além da distribuição, em termos de densidade e biomassa, também foram analisados o conteúdo estomacal dos indivíduos com o objetivo de observar a variação sazonal na dieta e possíveis sobreposições alimentares entre as diferentes fases ontogenéticas das espécies simpátricas. A sobreposição alimentar entre C. spixii e C. agassizii foi testada quando as diferentes fases ontogenéticas ocorreram no mesmo local. A precipitação sazonal das chuvas foi importante para definir a utilização dos habitats pelas diferentes fases ontogenéticas destas espécies ao longo do canal principal do estuário. A porção intermediária do estuário foi importante como local de berçário e alimentação para jovens, além de ser importante para alimentação de todas as espécies estudadas. Os bagres marinhos C. spixii e C. agassizii são predominantemente zoobentívoros, mas ao longo do seu ciclo de vida, e entre os diferentes locais e estações do ano, esta guilda trófica pode mudar para zooplanctívoro ou até mesmo oportunista. No início da estação seca, nas porções superior e intermediária do estuário, sub-adultos e adultos de C. spixii demonstraram sobreposição alimentar, principalmente pela elevada ingestão de Polychaeta e Ostracoda. No final da seca, no estuário superior, os adultos da espécie C. spixii apresentaram sobreposição alimentar com os jovens e adultos da espécie C. agassizii, devido à elevada ingestão de Gastropoda, Ostracoda e Calanoida. No início da chuva, na porção superior do estuário, foram observadas sobreposições na dieta de jovens e sub-adultos das duas espécies, e entre jovens e sub-adultos de C. agassizii, influenciadas pela alta ingestão de Ostracoda e Calanoida. No final da chuva, no estuário intermediário, essa sobreposição foi observada para jovens e subadultos de C. spixii e C. agassizii, devido à alta ingestão de Gastropoda, Calanoida e Harpacticoida. Durante este período, na porção inferior do estuário, C. spixii e C. agassizii jovens e sub-adultos demonstraram sobreposição alimentar, resultado da elevada ingestão de Gastropoda, Calanoida e Ostracoda. As espécies S. brasiliensis e S. stellifer são especialmente zoobentívoras, mas ao longo do ciclo de vida, entre as estações do ano e diferentes habitats, sua guilda trófica pode variar para oportunista ou até mesmo zooplanctívora. No final da estação chuvosa, na porção inferior do estuário, todas as fases ontogenéticas de ambas as espécies, com exceção de jovens de S. brasiliensis e adultos de S. stellifer, apresentaram sobreposição alimentar indicando a similaridade na utilização das presas. Esta sobreposição foi influenciada pelo consumo de Calanoida, Polychaeta e Eucarida por todas as fases das duas espécies. A ingestão de fragmentos azuis de nylon por todas as espécies estudadas foi observada como sendo um problema ambiental que deve ser discutido pelas autoridades e levado à comunidade. O conhecimento dos hábitos alimentares e a utilização dos habitats pelas diferentes fases ontogenéticas é essencial para entender o papel ecológico das populações de peixes, sendo uma ferramenta fundamental para o desenvolvimento de planos de manejo e conservação.
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Pombo, Maira. "Biologia populacional e dieta de Stellifer rastrifer (Jordan, 1889) S. stellifer (Bloch, 1790) e S. brasiliensis (Schultz, 1945) (Perciformes, Sciaenidae) na Enseada de Caraguatabuba (SP)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/21/21131/tde-02082011-120452/.
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A fim de colaborar com o conhecimento dos vários aspectos das diferentes populações e suas interações para o manejo e conservação dos recursos naturais, foram analisadas a dinâmica populacional e a dieta de três espécies do gênero Stellifer (Sciaenidae), coletadas de agosto de 2003 a outubro de 2004 em áreas rasas da Enseada de Caraguatatuba, com influência mínima dos rios e estuários da região. Os indivíduos de Stellifer rastrifer (n=3183), S. brasiliensis (n=357) e S. stellifer (n=116) concentraram-se em geral na porção sul da enseada e houve diferença entre o tamanho das três espécies (S. rastrifer > S. stellifer > S. brasiliensis), que apresentaram um padrão de variação do comprimento ao longo do tempo bastante semelhante. Todas se mostraram essencialmente carcinófagas, com variação sazonal dos itens alimentares e alta sobreposição alimentar entre elas. Stellifer rastrifer permitiu uma análise de aspectos reprodutivos e de crescimento. A quantidade de fêmeas com gônadas em maturação e maduras foi muito pequena, bem como os valores do índice gonadossomático foram baixos indicando que a área não seja usada para desova. Os valores estimados para os parâmetros de crescimento (L?=20,9, K=0,37 e Z=2,81) indicam que haja uma segregação espacial entre jovens e adultos e que a taxa de mortalidade encontrada deva incluir em sua composição uma elevada taxa de migração dos jovens para áreas mais profundas, onde se supõe que completem seu desenvolvimento.Intending to collaborate with some knowledge about ecosystems functioning for its suitable management and the conservation of natural resources, it was analyzed the populational dynamics and diet of three species belonging to the genus Stellifer (Sciaenidae), collected from August 2003 to October 2004, in shallow areas of Caraguatatuba Bay, where there was the least influence as possible of rivers and estuaries placed in the region. Species were Stellifer rastrifer (n=3183), S. brasiliensis (n=357) and S. Stellifer (n=116), wich focused at the southern area of the Bay. Species were significantly different from each other for size (S. rastrifer > S. stellifer > S. brasiliensis), although they have shown a quite similar pattern of length variation over time. They all fed upon basically crustaceans, with marked seasonal variation of food items and high dietary overlap among them. Stellifer rastrifer abundance allowed reproductive aspects analysis and the determination of growth parameters. The number of mature gonads in females was very small and gonadosomatic index values throughout the year were low, thus indicating that it is not a sapwn area. The growth parameters calculated (L?=20.9, K=0.37 and Z=2,81) indicate that there is a spatial segregation by size and that the mortality rate must, therefore, include a high rate of older individuals migration to deeper areas, where it is assumed that they complete their development.
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Araújo, Júnior Ildeu Bastos de [UNESP]. "Estudo da influência do resfriamento em revestimento de liga Stellite 6 aplicada pelo processo TIG." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/96481.
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A indústria busca uma melhor otimização e performance de seus equipamentos, há muito notou-se a importância da contenção do desgaste para o aumento de vida útil dos componentes de máquinas. Em condições operacionais onde há o desgaste por abrasão, comumente faz-se o endurecimento da camada superficial ou a aplicação de uma liga mais nobre e de dureza mais elevada, visando conter este desgaste. A técnica também é chamada de revestimento. Entender melhor os parâmetros que influenciam nos resultados da aplicação destes revestimentos torna-se importante possibilitando menores perdas e uma maior economia, pois busca-se como alvo trabalhar com a melhor performance do revestimento. Objetivou-se neste trabalho o estudo das ligas a base de Cobalto que são aplicadas cada vez mais rotineiramente nas indústrias petroquímicas, onde os componentes e órgãos de máquinas estão expostos a condições severas de desgaste por abrasão e corrosão além da severidade dos trabalhos a altas temperaturas e pressão. Relacionando o desgaste, as ligas a base de Cobalto possuem uma posição destacada e a liga é conhecida comercialmente como “Stellite 6”. Em alguns trabalhos é chamada também de liga coringa por sua versatilidade e destaque em especial. Neste trabalho procurou-se variar as velocidades de resfriamento em cinco patamares, analisou-se a influência da diluição na micro-dureza e os efeitos da variação da velocidade de resfriamento no mecanismo de endurecimento. A aplicação do revestimento ocorreu em três camadas através do processo TIG. Verificamos ainda a interferência da diluição na dureza em cada camada de revestimento. A terceira e última camada foi a que apresentou maior dureza devido à menor diluição com o metal base principalmente no corpo de prova que possuía à menor velocidade de resfriamento devido ao tempo para a formação de precipitados e carbonetos na liga metálica.
The industry searchs a better optimization and performance of their equipment, long noted the importance of containment to increase the wear life of components of machines. In operating conditions where there is wear by abrasion, usually it is the hardening of the surface layer or the application of a more noble alloy and high hardness, wear it to contain. The technique also called hardfacing. Better understand the parameters that influence the results of applying these coatings becomes important because it enables lower losses and greater economy as it seeks to target work with the best performance of the coating. The objective of this research is complements the study of cobalt-based alloys that are applied more routinely in petrochemical industries, where the component units and machines are exposed to severe conditions of wear by abrasion and corrosion than the severity of the work at high temperatures and pressure. Relating the wear, the cobalt-based alloys have a prominent position and the league is known commercially as “Stellite 6”. Some work is also called the league wildcard for its versatility and highlight in particular. In this work we have tried to vary the speed of cooling in five steps, looked up the influence of dilution on micro hardness and the effects of variation in the rate of cooling in the hardening mechanism. The application of the coating occurred in three layers using the TIG process. We note also the interference of dilution in hardness in each layer of coating. The third and final layer was the one with higher hardness due to less dilution with the base metal mainly in the body of evidence that had the lowest rate of cooling due to the time for the formation of precipitates and carbides in the metal.
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Araújo, Júnior Ildeu Bastos de. "Estudo da influência do resfriamento em revestimento de liga Stellite 6 aplicada pelo processo TIG /." Bauru :, 2009. http://hdl.handle.net/11449/96481.
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Orientador: Yukio KobayashiBanca: Gilberto de Magalh B. Gonçalves
Banca: Rodolfo Libardi
Resumo: A indústria busca uma melhor otimização e performance de seus equipamentos, há muito notou-se a importância da contenção do desgaste para o aumento de vida útil dos componentes de máquinas. Em condições operacionais onde há o desgaste por abrasão, comumente faz-se o endurecimento da camada superficial ou a aplicação de uma liga mais nobre e de dureza mais elevada, visando conter este desgaste. A técnica também é chamada de revestimento. Entender melhor os parâmetros que influenciam nos resultados da aplicação destes revestimentos torna-se importante possibilitando menores perdas e uma maior economia, pois busca-se como alvo trabalhar com a melhor performance do revestimento. Objetivou-se neste trabalho o estudo das ligas a base de Cobalto que são aplicadas cada vez mais rotineiramente nas indústrias petroquímicas, onde os componentes e órgãos de máquinas estão expostos a condições severas de desgaste por abrasão e corrosão além da severidade dos trabalhos a altas temperaturas e pressão. Relacionando o desgaste, as ligas a base de Cobalto possuem uma posição destacada e a liga é conhecida comercialmente como "Stellite 6". Em alguns trabalhos é chamada também de liga coringa por sua versatilidade e destaque em especial. Neste trabalho procurou-se variar as velocidades de resfriamento em cinco patamares, analisou-se a influência da diluição na micro-dureza e os efeitos da variação da velocidade de resfriamento no mecanismo de endurecimento. A aplicação do revestimento ocorreu em três camadas através do processo TIG. Verificamos ainda a interferência da diluição na dureza em cada camada de revestimento. A terceira e última camada foi a que apresentou maior dureza devido à menor diluição com o metal base principalmente no corpo de prova que possuía à menor velocidade de resfriamento devido ao tempo para a formação de precipitados e carbonetos na liga metálica
Abstract: The industry searchs a better optimization and performance of their equipment, long noted the importance of containment to increase the wear life of components of machines. In operating conditions where there is wear by abrasion, usually it is the hardening of the surface layer or the application of a more noble alloy and high hardness, wear it to contain. The technique also called hardfacing. Better understand the parameters that influence the results of applying these coatings becomes important because it enables lower losses and greater economy as it seeks to target work with the best performance of the coating. The objective of this research is complements the study of cobalt-based alloys that are applied more routinely in petrochemical industries, where the component units and machines are exposed to severe conditions of wear by abrasion and corrosion than the severity of the work at high temperatures and pressure. Relating the wear, the cobalt-based alloys have a prominent position and the league is known commercially as "Stellite 6". Some work is also called the league wildcard for its versatility and highlight in particular. In this work we have tried to vary the speed of cooling in five steps, looked up the influence of dilution on micro hardness and the effects of variation in the rate of cooling in the hardening mechanism. The application of the coating occurred in three layers using the TIG process. We note also the interference of dilution in hardness in each layer of coating. The third and final layer was the one with higher hardness due to less dilution with the base metal mainly in the body of evidence that had the lowest rate of cooling due to the time for the formation of precipitates and carbides in the metal
Mestre
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Rose, Simon Robert. "Studies of the high temperature tribological behaviour of some superalloys." Thesis, Northumbria University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324419.
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Moselli, Paulo Cesar. "Desenvolvimento de dispositivo, adaptado à tocha SATG, para a realização de revestimento duro, utilizando ligas, em forma de pó." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-03122013-223454/.
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Este trabalho inova a aplicação de revestimentos duros usando o processo de soldagem SATG (Soldagem ao Arco Tungstênio com Atmosfera Gasosa) utilizando ligas, em forma de pó, incorporadas diretamente à poça de solda. Devido à boa resistência ao desgaste, utilizou-se a liga Stellite 6, no substrato SAE 1020. Dados de microdureza Vickers, taxa de deposição, diluição, análise micrográfica e desgaste foram comparados com resultados do PAT-P (Plasma por Arco Transferido-Pó) e permitiram avaliar a técnica proposta. Os resultados mostraram um revestimento pelo processo SATG-pó livre de poros, sem oxidação na superfície e diluição superior, ao processo PAT-P. Porém, o consumo de gás foi menor, devido à redução da vazão do gás de arraste e da não utilização de gás plasma. A análise microestrutural evidenciou uma microestrutura similar, para ambos os processos, mas o processo PAT-P apresentou uma microestrutura mais refinada. Obteve-se, pelo processo SATG-pó semi-automático, microdurezas entre 400 e 500 HV e uma taxa de diluição de 5%, próximas aos valores do processo PAT-P. Quanto ao desgaste, observaram-se valores também bem próximos para os três processos.This work innovates the application of hardfacing by using the welding process GTAW (Gas Tungsten Arc Welding) using alloys in the powder form and directly embedded in the weld pool. Due to the good wear resistance it was used Stellite 6 alloy for hardfacing the substrate SAE 1020. Vickers hardness data, deposition rate, dilution, micrographic analysis and wear results were compared with the PTA-P (Plasma Transferred Arc-Powder) in order to evaluate the proposed technique. The results showed a coating produced by the process GTAW-powder free of pores, without surface oxidation and higher dilution in comparison with the PTA-P process. However, gas consumption was lower due to reduced flow of the carrier gas and as it was not used as plasma gas. Microstructural analysis showed a similar microstructure for both processes, but the PTA-P process presented a more refined microstructure. It was obtained, by the semi-automatic GTAW-powder process, micro hardness between 400 and 500HV and rate dilution of 5%, values close to the PTA-P process. As for the wear it was observed values very close too, for the three process.
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Kolton, Édison Pedroso. "Comportamento tribológico do par Stellite 6 e Colmonoy 56 utilizado em revestimento de mancal de extrusora monorosca." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/75718.
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O presente trabalho apresenta a avaliação comparativa do comportamento ao desgaste adesivo das ligas metálicas Stellite 6 e Colmonoy 56, aplicadas como revestimento resistente ao desgaste em diferentes combinações nos pares de corpos-de-prova ensaiados em laboratório segundo a norma técnica ASTM G-77. Procurou-se assim simular a condição mais crítica de operação, a qual um mancal dianteiro de deslizamento instalado internamente em uma extrusora monorosca está submetido, ou seja, contato metal-metal sem lubrificação. Uma vez que os resultados obtidos em laboratório indicaram o par com melhor desempenho em resposta às solicitações de desgaste adesivo, foram então, revestidas as superfícies das peças de um mancal de deslizamento e instaladas em uma extrusora monorosca para execução do teste de campo em condições normais de operação. A liga Colmonoy 56 utilizada em conjunto com a liga Stellite 6 mostrou ter uma vida útil maior ao desgaste por deslizamento do que o par de ligas Stellite 6 / Stellite 6. Os resultados indicaram ainda que quando o mecanismo predominante de desgaste por deslizamento é o adesivo, a compatibilidade metalúrgica entre as ligas metálicas que se atritam é um fator que influencia fortemente a resistência ao desgaste das superfícies em contato. Assim sendo, o par Colmonoy 56 / Stellite 6 apresentou uma menor compatibilidade metalúrgica (menor solubilidade mútua) melhorando o deslizamento devido a menor adesão entre as ligas. Outro fator que pôde ser constatado como de influência para a diminuição da taxa de desgaste foi à presença de alta concentração de cristais de boretos de cromo, que possuem dureza semelhante à do diamante, e também a presença de outros constituintes duros como carbonetos de cromo distribuídos na microestrutura do Colmonoy 56. Nos testes de campo, foi confirmado um significativo aumento da durabilidade do mancal em operação substituindo o par tribológico Stellite 6 / Stellite 6 pelo par Colmonoy 56 / Stellite 6.This work shows a comparative evaluation of the adhesive wear behavior of metallic alloys Stellite 6 and Colmonoy 56 applied as a wear resistant coating in different combinations in pairs of specimens tested in the laboratory according to technical standard ASTM G-77. We attempted to simulate then the most critical operating condition to which a sliding front bearing installed internally in a single screw extruder is subjected, i.e., metal to metal contact without lubrication. Since the results obtained in the laboratory indicated the par with the best performance in terms of response to adhesive wear were then coated surfaces of the parts of a sliding front bearing and after they were installed in a single screw extruder for run the field test in normal operation. The alloy Colmonoy 56 used in conjunction with alloy Stellite 6 proved to have a longer life than the pair of alloy Stellite 6 / Stellite 6 to sliding wear. The results also indicated that when the predominant mechanism of sliding wear is the adhesive, the metallurgical compatibility between the metal alloys that are rubbing each other is a factor that strongly influences the wear resistance of the surfaces in contact. Thus, the pair Colmonoy 56 / Stellite 6 demonstrated a lower metallurgical compatibility (mutual solubility smaller), improving the sliding between the alloys due to the lower adhesion between the alloy. Another factor found to influence to decrease the wear rate was the presence of high concentrations of crystals of borides of chromium, which have similar hardness to diamond and also the presence of other hard constituents, such as chromium carbides distributed in the microstructure of the Colmonoy 56. In field tests, it was confirmed a significant increase in the durability of the bearing under normal operation replacing the tribological pair Stellite 6 / Stellite 6 by tribological pair Colmonoy 56 / Stellite 6.
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Kinkenon, Douglas. "Tribological Behavior of Spark Plasma Sintered Tic/graphite/nickel Composites and Cobalt Alloys." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc407776/.
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Monolithic composites are needed that combine low friction and wear, high mechanical hardness, and high fracture toughness. Thin films and coatings are often unable to meet this engineering challenge as they can delaminate and fracture during operation ceasing to provide beneficial properties during service life. Two material systems were synthesized by spark plasma sintering (SPS) and were studied for their ability to meet these criteria. A dual hybrid composite was fabricated and consisted of a nickel matrix for fracture toughness, TiC for hardness and graphite for solid/self‐lubrication. An in‐situ reaction during processing resulted in the formation of TiC from elemental Ti and C powders. The composition was varied to determine its effects on tribological behavior. Stellite 21, a cobalt‐chrome‐molybdenum alloy, was also produced by SPS. Stellite 21 has low stacking fault energy and a hexagonal phase which forms during sliding that both contribute to low interfacial shear and friction. Samples were investigated by x‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x‐ray spectroscopy (EDS), and electron back‐scattered diffraction (EBSD). Tribological properties were characterized by pin on disc tribometry and wear rates were determined by profilometry and abrasion testing. Solid/self‐lubrication in the TiC/C/Ni system was investigated by Raman and Auger mapping. A tribofilm, which undergoes a stress‐induced phase transformation from polycrystalline graphite to amorphous carbon, was formed during sliding in the TiC/C/Ni system that is responsible for low friction and wear. TiC additions help to further decrease wear. Stellite 21 was also found to exhibit acceptably low friction and wear properties arising from the presence of Cr23C6 in the matrix and work hardening of the cobalt and chromium during sliding.
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Schmidt, Thassya Christina dos Santos. "Aspectos biológicos, com ênfase na reprodução das fêmeas, das principais espécies de Sciaenidae da Baía de Santos, costa central do Estado de São Paulo." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/21/21131/tde-01082011-132255/.
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O objetivo deste estudo foi descrever aspectos biológicos das espécies de cienídeos na baía de Santos. As coletas foram realizadas mensalmente, entre dezembro de 2004 e dezembro de 2005. Foram estudadas a composição específica; a estrutura populacional de dez espécies, incluindo idade e crescimento; a biologia reprodutiva de quatro espécies; e o tipo de fecundidade de Stellifer rastrifer. Foram capturados 29.306 exemplares pertencentes a 13 gêneros e 21 espécies, com S. rastrifer representando 70,4 % da composição total, seguido por Isopisthus parvipinnis e Stellifer brasiliensis, perfazendo 85%. A baía de Santos é caracterizada principalmente por indivíduos jovens, com a entrada de indivíduos para as populações ocorrendo em diversas épocas do ano. As análises reprodutivas e a confirmação histológica da maturação indicaram que as quatro principais espécies estudadas completam ciclo reprodutivo na região. As análises histológicas indicaram erros na identificação dos estádios macroscópicos dos ovários: fêmeas classificadas como \"em maturação\" (estádio B) foram reclassificadas como \"em reorganização\" após as análises microscópicas. Isopisthus parvipinnis e Stellifer brasiliensis apresentaram fêmeas desovantes nos meses de verão e Paralonchurus brasiliensis no inverno. A espécie Stellifer rastrifer apresentou distribuição de diâmetro dos ovócitos de maneira contínua, indicando que a espécie apresenta desenvolvimento assincrônico e fecundidade indeterminada.The goal of this study was to describe the biological aspects of Sciaenid species in Santos bay. Samplings were performed monthly, between November/2004 to December/2005. The specific composition; the population structures of ten species, including the age and growth; the reproductive biology of four species and the type of fecundity of Stellifer rastrifer were studied. In the present study 29,306 individuals were caught, belonging to 13 genus and 21 species, with the specie Stellifer rastrifer represented 70.4%, followed by Isopisthus parvipinnis and S. brasiliensis, resulting in 85% of the total Sciaenid composition. The Santos bay is mainly characterized by juveniles, with the recruitment of new individuals to the population occurring in several periods of the year. The reproductive analysis and the histological confirmation of the maturation stages indicated which the four main species studied complete their reproductive cycle in this region. The histological analysis indicated some errors in the identification of the macroscopic ovary stages, i.e., females classified as \"in maturation\" (stage B) were reclassified as \"in reorganization\" after the microscopic analysis. Hydrated females of Isopisthus parvipinnis and Stellifer brasiliensis occurred during the summer months while the hydrated females of Paralonchurus brasiliensis in the winter. The specie Stellifer rastrifer showed the oocytes diameter distribution in continuous pattern, indicating that the species has asynchronous development and indeterminate fecundity.
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Qiu, Wanfei. "Reproductive biology, space use and trophic status of Entomacrodus stellifer lighti (Pisces: Blenniidae) in Hong Kong." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31938747.
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Qiu, Wanfei, and 裘婉飛. "Reproductive biology, space use and trophic status of Entomacrodus stellifer lighti (Pisces: Blenniidae) in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31938747.
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Paleta, Petr. "Navařování kobaltové slitiny plazmou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-379012.
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The thesis deals with plasma overlay welding of cobalt alloys. In the theoretical part of the thesis, suitable cobalt alloys for plasma overlay welding were described, out of which cobalt alloy Stellite 21, was chosen for overlay welding for particular part. Subsequently, the plasma overlay welding machine PPC 250 PTM and the torch PHP 250 S, used in the practical part, were described. In the practical part were debug overlay welding parameters and suggest the suitable overlay welding procedure for particular part.
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Frehse, Fabrício de Andrade. "Estrutura populacional e dieta de Stellifer rastrifer (Jordan, 1889) e Stellifer brasiliensis (Schultz, 1945) (Scianeidae, Perciformes), nos periodos diurno e noturno, em quatro areas da plataforma sul do estado do Parana e norte do estado de Santa Cat." reponame:Repositório Institucional da UFPR, 2009. http://hdl.handle.net/1884/18392.
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Herčík, Tomáš. "Svařitelnost kobaltových slitin hybridní metodou Laser-TIG." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417054.
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The master thesis summarizes the critical situation of the lack of a cobalt used in different industry branches. Due to its increasing price, it will not be possible to use in existing applications. One of these applications is production of cobalt alloys where the replacement of this element is impossible. This type of material keeps mechanical properties at high temperature. However, a suitable choice of technology can achieve at least its savings. In the field of welding, the alloys are joined without any use of an additional material. The possible solution could be the use of hybrid technologies or electron beam. Verification of weldability of both methods was realised in experimental parts and evaluated by destructive methods. The investigation was performed on wear resistant alloy Stellite 6B.
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ALMEIDA, L. L. "Uso de Habitat e Recursos Alimentares Por Stellifer Brasiliensis (schultz, 1945) (perciformes, Sciaenidae) na Área de Proteção Ambiental de Conceição da Barra-es." Universidade Federal do Espírito Santo, 2018. http://repositorio.ufes.br/handle/10/9408.
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Previous issue date: 2018-02-20Este estudo visou descrever os hábitos alimentares e a utilização do habitat por Stellifer brasiliensis na Área de Proteção Ambiental (APA) de Conceição da Barra, Espírito Santo. Para tal, foi realizada a análise de conteúdo estomacal associada à análise de isótopos estáveis de carbono (δ13C) e nitrogênio (δ15N). Para se avaliar a utilização do habitat, foi avaliada a distribuição espaço-temporal da abundância, biomassa e comprimento total (CT, mm) da espécie. A ictiofauna foi amostrada mensalmente com redes de arrasto de fundo em quatro pontos distribuídos em um gradiente de salinidade. Para análise de abundância, biomassa e CT de juvenis e adultos, estas ocorreram entre maio/2014 e abril/2017; para a análise de conteúdo estomacal, entre julho/2015 e julho/2016; e para a análise de isótopos estáveis, peixes e presas foram coletados entre março/2016 e março/2017. As coletas de produtores primários ocorreram nos meses de abril, junho, agosto, setembro e dezembro/2016 e em junho/2017. A espécie apresentou maior abundância (F= 4,586, p<0,005) e biomassa (F= 7,139, p<0,005) no P4. Os maiores comprimentos foram registrados no inverno e outono no P1 e na primavera e verão no P4. Os itens alimentares de maior importância para a espécie foram Polychaeta, Thalassinidae e Penaeidae, para juvenis foram Penaeidae, Euphausiacea e Copepoda e para adultos foram Polychaeta, Thalassinidae e Copepoda. Os valores de δ13C de S. brasiliensis foram similares entre as estações, os pontos e as fases ontogenéticas e variaram de -17,45 ± 1,35 a -25,81 ± 0,67 nos juvenis e -18,28 ± 3,09 a -23,29 ± 1,37 nos adultos, enquanto as médias de δ15N variaram entre 12,73 ± 0,95 a 16,24 ± 0,32 nos juvenis e 13,83 ± 1,39 a 16,29 ± 0,68 nos adultos. As médias de δ15N indicaram que ambas as fases ocupam o mesmo nível trófico. As médias de δ13C nos juvenis e adultos no P1 foram similares aos valores de δ13C nos crustáceos Xyphopenaeus kroyeri e Alpheidae, indicando que estes são itens consumidos por ambas as fases ontogenéticas. Houve correlação negativa entre os valores de δ13C com o CT dos peixes, indicando que quando o peixe cresce, o valor de δ13C diminui, enquanto a correlação de δ15N foi positiva, indicando que quando o peixe cresce, o valor de δ15N aumenta. Palavras chave: Distribuição espacial, ecologia trófica, dieta, isótopos estáveis, bycatch
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Rodrigues, Filho Jorge Luiz. "Bioecologia de espécies do gênero Stellifer (Pisces, Sciaenidae) acompanhantes na pesca artesanal do camarão sete-barbas, na Armação do Itapocoroy, Penha, Santa Catarina, Brasil." Universidade Federal de São Carlos, 2008. https://repositorio.ufscar.br/handle/ufscar/1937.
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Previous issue date: 2008-04-04Universidade Federal de Sao Carlos
The fishery of sea-bob-shrimp Xiphopenaeus kroyeri with over-trawl nets with doors used by artisanal fishery is considered an efficient method for the capture of the target specie along the Brazilian Cost. However, it presents a low selectivity and captures a high amount of the demersal and benthonic fauna that are know as accompanying fauna. Among these, is frequently found that they of the target species, the fish of the genus Stellifer. Therefore, this study, aimed to determine the bioecological characteristics of fishes of this captured in fishing held in the Armação Itapocoroy, Penha, Santa Catarina, in two ways: in the first chapter, analyzing the population structure and the reproductive aspects of the species Stellifer rastrifer, Stellifer stellifer e Stellifer brasiliensis exploited in in the period of from april/2006 to march/2007 and, in the second chapter, assessing the annual and monthly abundance distributions of the exploited Stellifer spp. populations during the years of 1996 2006.
A pesca de arrasto com redes-de-porta praticada pela frota artesanal, dirigida ao camarão sete-barbas Xiphopenaeus kroyeri no litoral brasileiro é considerada eficiente na captura da espécie-alvo. Entretanto, apresenta baixa seletividade e incidentalmente captura grande contingente da fauna demersal e bentônica, agrupados sobre a denominação de fauna acompanhante. Dentre esses, destacamse, devido ao fato de possuírem o mesmo habitat que a espécie-alvo, os peixes do gênero Stellifer. Tendo por base esta constatação objetivou-se, no presente trabalho, determinar as características bioecológicas de espécies do gênero Stellifer ocorrentes na pesca artesanal realizadas em Armação do Itapocoroy, Penha, Santa Catarina, abordando dois aspectos: no primeiro capitulo, analisando a estrutura das populações e os aspectos reprodutivos das espécies Stellifer rastrifer, Stellifer stellifer e Stellifer brasiliensis, capturadas no período de abril/2006 a março/2007 e, no segundo capitulo, avaliando as distribuições mensais e anuais da abundância das populações de Stellifer spp. capturadas durante os anos de 1996 a 2006.
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Lubespère, André. "Ensemble de travaux de recherche concernant la bio-integration dans le milieu buccal, de materiaux metalliques a usage dento-prothetique et de divers moyens de rehabilitation de l'appareil stomatognatique." Toulouse 3, 1991. http://www.theses.fr/1991TOU35001.
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Golden, Christopher Lee. "Analysis of form errors in rings of non-uniform cross section due to workholding and machining loads." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22703.
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Cabrol, Elodie. "Étude et compréhension des mécanismes d'endommagement de surface de matrices de forgeage à chaud rechargées." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2015. http://www.theses.fr/2015EMAC0012.
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Dans le domaine du forgeage à chaud de pièces aéronautiques, les matrices en acier sont couramment rechargées, sur quelques millimètres d’épaisseur, par un alliage base cobalt (Stellite 21) déposé par procédé de soudage à l’arc (MIG). Dans le cadre de ce travail de thèse, ce rechargement « classique» est comparé à des rechargements Stellite 21 et Stellite 6 déposés par deux procédés émergents dans ce domaine, le PTA et le LASER. L’objectif est d’apporter des éléments de compréhension aux mécanismes d’endommagement de surface, notamment par écoulement plastique, de ces différents rechargements afin de dégager des voies d’amélioration pour augmenter la durée de vie des matrices. Pour cela, des essais tribologiques (semi-industriels et laboratoire) ont été mis en œuvre pour créer des endommagements de surface comparables à ceux observés sur matrices industrielles. Associées à ces essais, des investigations microstructurales, structurales et mécaniques multi-échelles ont été réalisées (traction, flexion, microdureté, MO, MEB, MEB-STEM, DRX, EBSD). Selon les couples « nuance/procédé » de rechargement, des mécanismes de déformation plastique par glissement des dislocations parfaites et par transformation de phase CFC en HC ont été identifiés. L’activation de ce dernier a pu être reliée à la température de transformation allotropique CFC/HC du cobalt. Cette température dépend à la fois (i) des éléments d’addition, variant en fonction de la nuance déposée (Cr, C,...), (ii) de la dilution (variation de la teneur en Fe) liée aux paramètres de soudage et (iii) du nombre de couches déposées. De plus, une influence significative de la transformation de phase sur l’évolution du coefficient de frottement a été mise en évidence. En effet, dans le cas où la transformation de phase n’est pas observée, le coefficient de frottement est stable durant l'essai alors qu'une chute de la courbe de coefficient de frottement a été reliée avec la transformation de phase CFC en HC. Parallèlement, l'écoulement plastique des dendrites est observé en extrême surface sur quelques dizaines de micromètre d'épaisseur dans la direction de glissement. Cet écoulement est associé à une forte texturation morphologique et cristallographique de la phase identifiée (CFC ou HC), avec une orientation des plans de plus grande densité atomique parallèlement à la surface de glissement. Les résultats montrent également que sous sollicitations tribologiques, un important durcissement est observé en surface (jusqu'à 90%) et une corrélation a pu être établie entre l'augmentation de la microdureté et le taux de déformation plastiqueIn the field of hot forging of aeronautical parts, the steel dies are commonly hardfaced, on few millimeters thick, by a cobalt-based alloy (Stellite 21) deposited by arc welding (MIG). As part of this thesis, this "classic" hardfacing is compared to Stellite 21 and Stellite 6 hardfacings deposited by two emerging processes in this area, the PTA and the LASER one. The objective is to assess surface damage mechanisms, especially induced by plastic strain, of these various hardfacings. Tribological tests (laboratory and semi-industrial) were used to create surface damage comparable to those observed in industrial dies. Associated with these tests, multiscale microstructural, structural and mechanical investigations have been performed (tensile, bending, microhardness, OM, SEM, STEM, XRD, EBSD). According to the « material/process » couple, plastic strain mechanisms by perfect dislocation glide and by FCC to HCP phase transformation have been identified. The activation of the latter has been connected to the temperature of the allotropic phase transformation (FCC/HCP) in cobalt. This temperature depends on (i) the alloying elements, varying according to the deposited grade (Cr, C, ...), (ii) the dilution (Fe content evolution) connected to the welding parameters and (iii) the number of deposited layer. Moreover, a significant influence of the phase transformation on the evolution of the friction coefficient has been evidenced. Indeed, if the phase transformation is not observed, the friction coefficient is stable during the test, while a drop of the friction coefficient curve is connected with the FCC to HCP phase transformation. Moreover, the plastic flow of dendrites is observed at the extreme surface, on a few tens of micrometres in thickness, in the direction of sliding. It is associated with a high morphologic and crystallographic texturing of the identified phase (FCC or HCP), with the highest atomic density planes mostly oriented parallel to the sliding surface. The results also show that, under tribological laodings, a significant hardening is observed on the surface (up to 90%) and a correlation has been established between the increase in the microhardness and the plastic deformation ratio
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(9802514), Md Shahanur Hasan. "Optimisation of machining processes design for Stellite 6, a wear resistant and difficult-to-machine material." Thesis, 2011. https://figshare.com/articles/thesis/Optimisation_of_machining_processes_design_for_Stellite_6_a_wear_resistant_and_difficult-to-machine_material/13461239.
Full textAbstract:
"The research work in this thesis involves a series of physical experiments and theoretical investigations for machining of Stellite 6 using PCBN (Polycrystalline Cubic Boron Nitride) and coated carbide inserts for the optimisation of cutting parameters (cutting speed, feed rate, depth of cut and nose radius) on the basis of surface roughness and surface integrity"--Abstract.
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Zhu, Jin-De, and 朱晉德. "Wimax-Bsed Ka Band LEO Multi-Stellite Transmission Scheme." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/80726799415645378630.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
98
In this thesis, we propose a Wimax-based multi-satellites communication scheme in Ka band. Power assignment mechanism, OFDMA direct mapping (DM) and space-time block code (STBC) transmission strategies, unequal error protection, adaptive modulation, and channel estimation are used in the proposed communication scheme. For maximizing resource utilization and minimizing the total transmission power, STBC and adaptive modulation techniques are used in the proposed Wimax-based mobile satellite system. Further, low power, direct mapping (DM) , low-error protection scheme, and high-level modulation are adopted for messages that can tolerate a high BER. With the proposed transmission scheme, the required reliability of communication can be achieved. Our simulation results have shown that the proposed Wimax-based satellite transmission scheme can be used for developing effective mobile application systems.
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Yung-JenShih and 施詠仁. "Wear Characteristics of Stellite 1 and SKH51 Friction Stir Tools." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/91827522488761815620.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
98
The surface overlaying treatment is aimed to enhance surface properties of materials such as microhardness, wear-resistance, corrosion -resistance and etc. In this study, Stellite 1 cobalt-based alloy was overlaid on SKD61 steel by plasma transfer arc (PTA) process to form SKD61-ST1 friction stir tool for friction stir welding and process (FSW/FSP). The solidification structure of overlayer was explored. Furthermore, the wear resistance of SKD61-ST1, annealed SKH51 (SKH51-A) and tempered SKH51 (SKH51-T) high speed steel friction stir tools was evaluated by FSP test in which 5083 aluminum alloy was processed. The wear characteristics of SKD61-ST1, SKH51-A and SKH51-T friction stir tools were compared and studied as well. Results indicated that Stellite 1 overlayer of SKD61-ST1 is hypereutectic structure with large amount of M7C3 and M23C6 carbides under 90A overlaying current. The phase of matrix is ?-Co. Applying SKD61-ST1, SKH51-A and SKH51-T to FSP tests, sliding wear occurs and weight loss results revealed that the wear resistance of SKD61-ST1 is the highest. In addition, according to SEM and EPMA analysis, a transfer layer containing fragments from both sliding parts was formed on the interface between 5083 aluminum alloy and friction stir tools after FSP. It was proposed that the decohesion of transfer layer results in the weight loss of friction stir tools. Analyzing the transfer layers one step further by Thin Film XRD, Al9Co2 was found in the case of SKD61-ST1; however, Al5Fe2 and AlFe occur in the cases of SKH51-T and SKH51-A. The formation of these compounds is similar to the process of mechanical alloying in a ball mill. Thickness and coverage of transfer layers on friction stir tools were measured by SEM. Since SKH51-A is softer than SKH51-T, both thickness and coverage of transfer layer on SKH51-A were greater than that of SKH51-T. Nevertheless, thickness and coverage of transfer layer on SKD61-ST1 is thinnest and lowest among the three cases although SKD61-ST1 is softer than SKH51-T. It is proposed that hardness is not the only factor to influence transfer layer and wear characteristics of friction stir tools. Compatibilities and adhesion energies between Al-Co and Al-Fe also play significant roles in this study.
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Hsia, Kuang-Hsuan, and 夏廣烜. "Application of Direct Laser Deposition to Stellite 6 Rollers Forming." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2f3a7m.
Full textAbstract:
碩士國立中山大學
機械與機電工程學系研究所
107
Directed energy deposition is one of the categories in additive manufacturing. The metal powder is pushed through a nozzle where it is melted by laser beam, then it drops into the molten pool and deposits on the substrate. The cladding layer is sensitive to the process parameters. Therefore, the geometry of cladding layer is taken to verified which set of parameters has good quality. It could reduce the waste of cladding materials and manufacturing time in application by controlling the quality of the cladding layer. Stellite 6 alloy powder is chosen to be the cladding material in this research, and the medium carbon steel S45C is chosen as the substrate material. In the single-track cladding experiment, three variables which have selected range are investigated: laser power, scan rate, and mass flow rate. As the result of measurement, the bead which is eligible to apply on multi-track overlapping cladding experiment should meet the four conditions: depth is greater than 0.2mm, dilution is less than 0.4, aspect ratio is between 2 to 3, and the contact angle is greater than 90 degrees. Accordingly, the overlapping rate of multi-track experiment can be set as the range from 10% to 50% . The quality is verified with the maximum waviness contour value of surface profiles. As the result, the process parameters could be applied on forming the rollers of turrets of lobe cam reducer. The profiles of forming rollers need to be measured, including the hardness, shear strength, and the dimensional accuracy. After that, setting up the experimental platform and assembling the cam reducer. The running test are within the range of 270-900rpm rotational speed, 0-30N-m output-torque. According to the test results of roller and reducer, the applicability and breakthrough of this research could be figured out.
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Gonçalves, Francisco António Pereira. "Avaliação tecnológica de aplicações industriais para processos de revestimento por Laser Cladding." Master's thesis, 2017. http://hdl.handle.net/10316/83309.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaEste trabalho realizado em ambiente empresarial tem dois objetivos principais. Em primeiro lugar a realização de uma avaliação tecnológica e de aplicações industriais para revestimentos por laser cladding, assim como a realização de uma análise à evolução da tecnologia laser e uma análise dos materiais mais utilizados, substratos e revestimentos, no processo de revestimento por laser cladding. Em segundo lugar este trabalho tem como objetivo comparar duas tecnologias de revestimento, uma mais tradicional, os revestimentos obtidos por soldadura MIG, e outra mais recente, a tecnologia de revestimentos por laser cladding. De forma a comparar as duas tecnologias é feita a caracterização do revestimento de uma superliga de Cobalto, a Stellite® 6, depositado com ambas as tecnologias, sobre um substrato de aço inoxidável austenítico AISI 316L. Nesta comparação os revestimentos são analisados a nível macroscópico (medição da diluição do revestimento no substrato, medição espessura do revestimento, cálculo da energia adicionada), a nível microscópico é analisada a microestrutura dos revestimentos assim como a sua composição química através de microscopia ótica, eletrónica e espetrometria, são ainda efetuados ensaios de desgaste por abrasão segundo a norma ASTM G65 e ensaios de microdureza.Por fim, é feita uma análise económica onde são comparados alguns custos diretos, como o custo do material depositado, os custos de maquinação e o custo da duração do processo de revestimento através das tecnologias de soldadura MIG e laser cladding.
This work has two main objectives, the first objective is to do an evaluation of the laser cladding coating technology and its industrial applications, as well as an analysis of the evolution of the laser technology and an analysis of the most common materials, coatings and substrates, used in laser cladding coatings. In second place this work focus on the comparison between a traditional coating technology, the MIG welding coatings, and the laser cladding coatings. In order to compare these two technologies, a coating of a Cobalt super alloy, Stellite® 6, deposited by both technologies in an austenitic stainless steel AISI 316L is studied. In this comparison the coatings are analysed macroscopically (measuring of the dilution of the coating in the substrate, measuring of coating thickness, calculation of added energy). Microscopically this characterization consists in the analysis of the chemical composition and microstructure of the coatings, this using optical and electronic microscopy. The abrasion resistance according to ASTM G65 standard test and the micro hardness of the coatings are also tested.Finally an economic analysis is made, where some of the direct costs of both coating technologies are compared in order to avaluate which one is as the lowest costs. In this analysis are considered the cost of the deposited material, the machining costs, in which is considered the machining time cost, as well as the cost of the tools,and the cost of the time of the coating process.
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Hermesmann, Christopher Marc. "Thermal simulations for the prediction of porosity in investment castings for stellite grade superalloys." Thesis, 1996. http://hdl.handle.net/2429/5877.
Full textAbstract:
A computer model was constructed and run to predict the thermal history of a
Stellite alloy investment casting prone to the formation of microporosity. The thermal
history of the casting was utilized to calculate the thermal gradient at a specified
temperature, the rate of cooling during solidification, and the solidification velocity.
These parameters were combined in a manner consistent with the formulation of two
different criteria (Niyama and L.C.C. criteria) used to predict porosity. The Niyama and
L.C.C. criteria successfully predicted the distribution of porosity found in the actual
investment casting. Several new casting configurations were designed and modeled on
computer until a configuration was constructed that predicted very little or zero porosity
in the problematic areas. A new casting configuration, similar to the one designed in this
study, was designed and cast by the industrial sponsor. The computer simulation of the
casting configuration by the industrial sponsor predicted a small pocket of microporosity.
Upon examination, some microporosity, consistent with the predictions by the model,
was discovered. The finite element modeling software (ProCAST™) and the Niyama and
the L.C.C. criteria served as excellent tools for predicting porosity in Stellite alloy
castings.
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Lei, Hsueh-Chung, and 雷學忠. "Effect of NbC Addition on Microstructure and Surface Performance of Stellite6 Cobalt-based Alloy PTA Coating Layer on Spheroidal Graphite Cast Iron." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h573ad.
Full textAbstract:
碩士遠東科技大學
機械工程研究所在職專班
107
In this study, Stellite6 alloys were respectively overlaid on spheroidal graphite(SG) cast irons with 3.0 wt% carbon and 2.8 wt% silicon by plasma transferred arc (PTA) process in the fixed overlaying speed, travel speed and overlaying current by changing the additive content of NbC in the Stellite6 alloys. To explore its influence on the solidification structure of the overlayer and the interface region. In the study, we also used the overlayer with the NbC additve in cobalt-base superalloys for the cutting wear test to explore the effects of different the additive content of NbC in the Stellite6 alloys on the microhardness, the amount of carbides and the cutting wear characteristics of the overlayer. The results reveal that the Stellite6 overlayer melted on SG cast iron with 3.0 wt% carbon and 2.8 wt% silicon under overlaying current (I=100A) is a dendritic structure with M7C3 and M23C6 carbides and matrix structure is -Co. The micro-hardness (Hv) and bulk hardness (HRC) of the overlayer increases with the addition amount of NbC. The results of the cutting wear test show that the flank wear of the Stellite6 cobalt-based alloy overlayer does not increase with the addition of NbC, but it is found that when 30 wt% NbC carbide is added, that have better wear resistance. In the cutting wear test, the wear mechanisms of overlayers are mainly plastic groove, surface polish and adhesive wear as adhered to overlayers. Others minor mechanicsms include brittle crack and fracture. Among these, the case to plastic groove includes microcutting and plough. Keywords: plasma transferred arc, overlaying current, Stellite alloy, spheroidal graphite cast iron, wear .
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LIN, RONG-SONG, and 林榮崧. "不銹鋼410，17-4PH及鈷基超合StelliteNo.6之銀合金硬銲研究." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/27578895373930825746.
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Lin, Rong-Song, and 林榮崧. "410不銹鋼、17-4PH不銹鋼及StelliteNo.6鈷基超合金之銀合金硬銲研究." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/19447066008201554430.
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De, Beer Richard John. "Group actions and ergodic theory on Banach function spaces / Richard John de Beer." Thesis, 2014. http://hdl.handle.net/10394/11536.
Full textAbstract:
This thesis is an account of our study of two branches of dynamical systems
theory, namely the mean and pointwise ergodic theory.
In our work on mean ergodic theorems, we investigate the spectral theory of
integrable actions of a locally compact abelian group on a locally convex vector
space. We start with an analysis of various spectral subspaces induced by the action
of the group. This is applied to analyse the spectral theory of operators on the
space generated by measures on the group. We apply these results to derive general
Tauberian theorems that apply to arbitrary locally compact abelian groups acting on
a large class of locally convex vector spaces which includes Fr echet spaces. We show
how these theorems simplify the derivation of Mean Ergodic theorems.
Next we turn to the topic of pointwise ergodic theorems. We analyse the Transfer
Principle, which is used to generate weak type maximal inequalities for ergodic
operators, and extend it to the general case of -compact locally compact Hausdor
groups acting measure-preservingly on - nite measure spaces. We show how
the techniques developed here generate various weak type maximal inequalities on
di erent Banach function spaces, and how the properties of these function spaces in-
uence the weak type inequalities that can be obtained. Finally, we demonstrate how
the techniques developed imply almost sure pointwise convergence of a wide class of
ergodic averages.
Our investigations of these two parts of ergodic theory are uni ed by the techniques
used - locally convex vector spaces, harmonic analysis, measure theory - and
by the strong interaction of the nal results, which are obtained in greater generality
than hitherto achieved.PhD (Mathematics), North-West University, Potchefstroom Campus, 2014