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1
Errico, Antonio. « Deformazioni del suolo in aree vulcaniche : applicazioni ai Campi Flegrei e a Stromboli ». Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/885.
Texte intégralRésumé :
2011 - 2012Nella notte tra il 24 e 25 agosto del 79 d.C. villaggi e città vennero distrutti e migliaia di persone persero la vita per l' improvvisa eruzione del Vesuvio. Le rovine di Pompei ed Ercolano, sepolte e conservate dai prodotti di quell' eruzione, ci mostrano una istantanea della vita di duemila anni fa ma ci portano anche ad immaginare quale ansia e quale terrore abbiano provato le persone in quel momento. Ancora oggi le eruzioni vulcaniche provocano morte e distruzione in tutto il pianeta ma, rispetto agli inizi del primo millennio tanto è stato fatto per capire il meccanismo che regola questi eventi catastro ci. L' obiettivo dei geo sici è quello di prevedere eventuali eruzioni vulcaniche attraverso lo studio di segnali premonitori, se ce ne sono. A questo scopo negli anni tra il 2004 e il 2006 è stata istallata una rete di dilatometri nei Campi Flegrei, sul Vesuvio e sull' isola di Stromboli, mentre nel periodo 2008-2009 nei Campi Flegrei è stata istallata una rete di inclinometri a base lunga. L' obiettivo di questa tesi è lo studio delle deformazioni lente del suolo come e etto dell' intrusione di magma all' interno della camera magmatica dei Campi Flegrei ed una analisi statistica degli sciami di esplosioni che si veri cano sull' isola di Stromboli. Nel prosieguo del lavoro è stata data una descrizione dei dilatometri da pozzo di tipo Sacks-Evertson e degli inclinometri a base lunga. L' utilizzo di questi strumenti segue il modello del campo delle deformazioni nel range delle basse frequenze monitorando il tensore delle deformazioni nelle sue componenti non diagonali, per le inclinazioni pure (inclinometri) e le sue componenti diagonali, per le deformazioni (dilatometri). E' stato dato un largo spazio ai fenomeni che regolano le deformazioni della crosta terrestre facendo un' ampia digressione sulla teoria dell' elasticità e sulla teoria che regola le maree. E' stata fatta, inoltre, una analisi statistica degli sciami di esplosioni del vulcano Stromboli in tre periodi distinti usando i dati registrati da sismometri di tipo Lennartz e Guralp. Successivamente è stato fatto un confronto tra questi dati sismici con i dati dilatometrici registrati da un dilatometro, anch' esso di tipo Sacks-Evertson, istallato sull' isola di Stromboli. [a cura dell'autore]
XI n.s.
2
Pouchlý, Václav. « Slinování pokročilých keramických materiálů s využitím vysokoteplotní dilatometrie ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228398.
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This diploma work is focused on exploitation of high-temperature dilatometry in sintering of advanced ceramic materials. Newly developed software is presented in this diploma work. This software is able to calculate activation energy of sintering process via concept of Master Sintering Curve. In the second part of diploma work the software was verified by evaluation of sintering of four different ceramics materials. The following activation energies of sintering were calculated: 990kJ/mol for tetragonal ZrO2 (3mol% Y2O3), 620kJ/mol for cubic ZrO2 (8mol% Y2O3) and 640kJ/mol resp. 720kJ for Al2O3 with two different particle size.
3
Matsubara, Daniel Bojikian. « Caracterização de chapa grossa de aço microligado temperado por meio da técnica de dilatometria ». Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-23102015-155738/.
Texte intégralRésumé :
Foram coletadas amostras de uma chapa grossa temperada, de aço microligado ao boro com 8 mm de espessura. O aço foi produzido em aciaria do tipo LD, laminado na forma de chapa grossa em laminador de cadeira única reversível e finalmente recebeu tratamento de têmpera em forno de tubos radiantes e máquina de têmpera com fluxo de água. Todas as etapas de produção tiveram os parâmetros de processo controlados para obtenção das melhores propriedades possíveis. As amostras foram retiradas da região situada a um quarto da largura da chapa e submetidas a diversos ciclos térmicos em aparelho de dilatometria. Com auxílio de técnicas de microscopia ótica, microscopia eletrônica de varredura e medidas de dureza, o aço pôde ser caracterizado e foi possível levantar as curvas de resfriamento contínuo (TRC). As microestruturas revelaram a presença de múltiplos microconstituintes, principalmente em resfriamentos a partir de resfriamentos 25°C/s, quando surgem elementos aciculares como ferrita acicular e bainita misturados com ferrita poligonal e perlita. Acima desta taxa de resfriamento o campo perlítico é suprimido e a partir de 45°C/s surge a martensita. A 100°C/s a microestrutura é dominada predominantemente por martensita. As amostras resfriadas nas 3 taxas mais severas também revelaram a presença de austenita retida e constituinte MA, detectados por meio de difração de raios-x e ataque com reagente de Klemm.Samples were taken from a quenched plate with 8mm thickness and chemical composition consisting of carbon, manganese, silicon, aluminum, niobium, titanium and boron. The steel was produced in LD converter, rolled in a reversible single chair rolling mill and quenched in a radiating tube furnace and quenching machine with water flow. All production stages had the process parameters controlled to obtain the best possible properties. The samples were extracted from a position situated at one quarter of the plate´s width and submitted to various thermal cycles in dilatometry device. With the aid of optical microscopy, scanning electron microscopy and hardness measurements, the steel could be characterized and the continuous cooling transformation curves could (CCT) be plotted. The microstructures revealed the presence of multiple components, especially when cooling rates reach 25°C/s, where acicular elements, like acicular ferrite and bainite, are found along with polygonal ferrite and pearlite. Above this cooling rate the pearlite field is suppressed and starting at 45°C/s martensite was found. At 100°C/s the microstructure is mainly martensitic. The samples cooled at the 3 most severe rates also revealed the presence of retained austenite and MA constituent, which were detected by x-ray diffraction and attack using Klemm reagent.
4
Pouchlý, Václav. « Slinování pokročilých keramických materiálů ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234142.
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Sintering is a one of the key step in a processing of bulk ceramic materials. New sintering methods were invented in the last years. These new sintering methods, according to their authors, can be used for obtaining finer final microstructure of ceramics only by modifying the heating schedule. This work is focused on an influence of the Two Step Sintering method on the final microstructure for oxide ceramics. Obtained experimental results have shown that the effectivity of the Two Step Sintering method is rising with crystallographic symmetry of used material. Thesis is also focused on a high-temperature dilatometry and concept of the Master Sintering Curve. This concept was used for calculation of the activation energy of sintering and finding different sintering mechanisms acting in the intermediate and final stage of sintering. Activation energy of sintering was compared with activation energy of grain growth with target to find the kinetic window. Kinetic window can allow a sintering without a grain growth. Master Sintering Curve method was also used in a pressure assisted unconventional sintering technique Spark Plasma Sintering. Master Sintering Curve applied to a Spark Plasma Sintering technique reveals and quantified different sintering mechanisms acting in Spark Plasma Sintering. These findings led to preparation of transparent tetragonal ZrO2.
5
Mařák, Vojtěch. « Příprava a vlastnosti dopovaných piezokeramických materiálů na bázi BaTiO3 ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417065.
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This diploma thesis deals with the preparation of doped piezoceramic materials based on BaTiO3 using electrophoretic deposition. Five rare earth oxides, i.e. Er2O3, Dy2O3, Eu2O3, Tb407 and CeO2, were used as dopants in amounts of 1, 3, and 5 wt. %. The prepared deposits were evaluated in terms of preparation methodology, high temperature dilatometry, X-ray diffraction analysis, relative density, mean grain size, hardness and fractographic analysis. The study of dilatometric curves described the sintering behavior and its changes at different material compositions. X-ray diffraction analysis revealed a tetragonal phase in all samples; the tetragonality of the BaTiO3 crystalline cell decreased with dopant content. By a suitable choice of dopant, it was possible to significantly increase the relative density of sintered samples, their hardness and at the same time prevent the samples from coarsening of the microstructure during heat treatment. A relative density up to 98 %, a mean grain size below 1 m and a hardness of over 10 GPa were achieved. Analysis of the fracture surfaces revealed that the fracture mode was transcrystalline for the most of studied materials; only the samples doped with cerium dioxide had fracture surfaces with both transcrystalline and intercrystalline fracture modes. Based on the obtained results, a suitable composition of the material for the intended use in a layered piezoceramic harvester was identified, which, in addition to the BaTiO3 layers, consists of functionally-protective Al2O3 and ZrO2 layers.
6
Casarin, Samuel Jose. « Caracterização da temperabilidade de um aço C-Mn microligado ao boro, através de dilatometria e curvas de transformações de fases por resfriamento contínuo ». Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-29012010-160947/.
Texte intégralRésumé :
No presente trabalho, foi realizado um estudo sobre a influência da adição do boro em um aço C-Mn, nas transformações de fases por resfriamento contínuo, através da técnica dilatométrica. Para este estudo, utilizou-se dois aços de composição química semelhante: o aço 10B22 com 30 ppm de boro e o aço sem boro é o E1522, equivalente. Foram traçadas as curvas de CCT dos dois aços, onde analisou-se o efeito de temperabilidade do boro através das curvas de resfriamento. Os materiais foram ensaiados em um dilatômetro de resfriamento rápido, utilizando corpos de prova cilíndricos, resfriados por injeção de ar e hélio. Os resultados gráficos dos processos de resfriamento foram comparados com análises metalográficas ótica estruturais e quantitativas e também por medidas de dureza. Detalhes microestruturais, tais como, contagem de fases formadas em função das taxas de resfriamento, tamanho de grão, distribuição de inclusões e precipitados, foram extraídos, através de um sistema de análise de imagens. Complementando o trabalho, foi realizado uma completa documentação fotográfica das microestruturas, com uma indicação final do tratamento térmico mais adequado aos aços C-Mn microligados ao boro.This work presents a study about the influence of boron on phase transformation by continuous cooling in a C-Mn steel using the dilatometric technique. For this study two close chemical composition steels were applied: a 10B2 steel with 30 ppm of boron and a E1522 steel without boron. For both steels the CCT curves were obtained, where the effect of boron on hardenability was analysed throughout continuous cooling curves. Both materials were testedcin a high speed quenching dilatometer, using cilindricals samples quenched by helium blow on their surfaces. The graphics results of cooling processes were compared with microstructural and quantitative optical metallographic analysis and hardness measurements. Microstructural features as such phases fraction as a function of cooling rates, grain size, and distributions of inclusions and precipitates were obtained through an image analysis system. In addition, complete microstructural photography documentation was carried out where it was possible to indicate the best heat treatment to boron microalloyed C-Mn steels.
7
Casarin, Samuel José. « Transformações de fases isotérmicas por dilatometria do aço SAE 1070 : curva TTT ». Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/18/18136/tde-16092009-093825/.
Texte intégralRésumé :
A proposta de desenvolvimento deste trabalho de dissertação veio de encontro com o objetivo de adaptar um laboratório para pesquisas em transformações de fases, utilizando o método dilatométrico, onde foram estudadas as reações no estado sólido que sofrem os materiais submetidos a ciclos térmicos. Para atingir este objetivo, instalou-se recentemente um dilatômetro de resfriamento rápido, modelo DT 1000 da Adamel Lhomargy. Completada a etapa de instalação do equipamento, o passo seguinte consistiu em explorar, através de ciclos térmicos variados, todos os recursos manipuláveis do dilatômetro. Aplicando a técnica dilatometrica em um aço de características termomecânicas conhecidas - SAE 1070 - possibilitou-se, a partir deste trabalho, que pesquisas mais complexas pudessem ser executadas com tal equipamento ou que o mesmo servisse como um instrumento complementar para estudos de transformações de fases. Nessa fase inicial de investigações estudou-se as curvas dilatométricas a fim de verificar os tempos de início e fim de transformação isotérmica em várias temperaturas de decomposição da austenita. Traçou-se as curvas de transformação isotérmica - curvas TTT - para o aço ensaiado (tratado termicamente), onde analisou-se a influência desse tratamento térmico prévio (recozimento) sobre a transformação \'alfa\' para \'gama\'. Finalizando a parte prática deste trabalho, comprovou-se as transformações de fases isotérmicas nas várias temperaturas ensaiadas, através de análise metalográfica e de medidas de microdureza dos produtos obtidos. A fim de solucionar eventuais problemas relacionados ao manuseio e manutenção do equipamento, com base na experiência adquirida ao longo do desenvolvimento deste trabalho, são dadas sugestões de possíveis aplicações do dilatômetro de têmpera rápida DT 1000 em pesquisas de transformações de fases.The purpose of this work comes together with the objective to adapt a phase transformation research laboratory using dilatometric method, where it will be possible to study the solid state reactions of materials submited to thermal cycles. To fulfil this purpose, it was installed a high speed quenching dilatometer, model DT 1000 manufactured by Adamel Lhomargy. After this stage, our next step was to explorer all equipment resources through variable thermal cycles. Appling dilatometric method to a well known thermomechanical steel - SAE 1070 - it becomes possible the accomplishment of more complex experiments with this equipment. This equipment, itself, may be a powerfull auxilliary instrument to phase transformations studies. In this first investigation, it was studied the dilatometric curves to find the beginning and the end times of isothermal phase transformation for several austenite decomposition temperatures - TTT diagram - for the tested steel (thermal treated). The effect of this previous heat treatment (annealing) on the \'alfa\' for \'gama\' transformation were observed. Finally, the isothermal phase transformation at the different tested temperatures could be confirmed through metallographic and microhardness analysis. In order to solve possible problems associated to the equipment use or maintenance, some suggestions of applications of the high speed quenching dilatometer are indicated for further works.
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Solem, Benjamin. « Dilatometry Study of a High-Chromium Cast Iron ». Thesis, KTH, Hållfasthetslära (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232528.
Texte intégralRésumé :
High-chromium cast irons are used in certain applications where the demand on abrasion resistance is high. Such applications can be found in the milling industry and in pumps for transport of abrasive particles in liquid suspension. Soft annealed high-chromium cast iron containing 2.6 % C and 24.7 % Cr was supplied by Xylem Water Solutions, Sundbyberg, and investigated by dilatometry. The heat treatments were inspired by induction hardening procedures. The purpose of the investigation was to evaluate the effect of maximum temperature reached during heat treatment on the final length of the test specimen. The aim with this was to find the treatment yielding the maximum possible length which should be profitable to create desirable compressive stresses in the surface hardened area. The experimental results were used to create a finite element model in COMSOL Multiphysics accommodating for the maximum temperature, simulating the phase changes occurring in a geometry based on the experimental test specimen. The experimental results did not reveal any clear correlation between the maximum temperature and the final length change. The hardness, however, increased with the increasing temperature in the treatment interval 900-1150 °C. The, by light optical microscopy, observed amount of secondary precipitated carbides decreased with increasing temperature. Martensite transformation was also affected; the transformation temperature decreased for increased treatment temperatures. From dilatometry it was also seen that the thermal strains were greatly affected by the direction of which the material was cut from the original cast material. Samples taken perpendicular to the mainly investigated direction showed lower coefficients of thermal expansion and the final strain was clearly positive compared to the slightly negative values found for the main direction. This phenomenon could possibly be explained by different macrostructures created during solidification of the melt causing anisotropy in the eutectic. The implementation in COMSOL by describing the phase transformation as ordinary differential equations did show partially good results in the simulation of thermal expansion. The difference in original material is noticeable in the dilatometry and the simulated martensite transformation deviates from the experimental results. The model needs to be validated against new intermediate test temperatures and the martensite transformation kinetics must be investigated further to yield better results to be able to combine the phase transformations with mechanical calculations.
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Kinkelaar, Mark Richard. « Dilatometric study of low profile unsaturated polyester resins / ». The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848078450146.
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Carvalho, Leandro Gomes de. « Estudo dilatométrico das transformações de fase em aços maraging M300 e M350 ». Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-26032012-112344/.
Texte intégralRésumé :
Os aços maraging são aços de baixo teor de carbono com estrutura martensítica (CCC), que são endurecidos pela precipitação de fases intermetálicas. O objetivo deste trabalho é estudar as transformações de fases desses aços: precipitação, reversão da martensita para a austenita e transformação martensítica. Nesse trabalho, foram caracterizadas uma corrida de aço maraging da série 300 e três corridas da série 350, usando diversas técnicas complementares: microscopia ótica, microscopia eletrônica de varredura com análise dispersiva de energia, microdurômetro, difração de raios-X, ferritoscópio e dilatometria. Os resultados obtidos mostraram que as corridas com maiores teores de cobalto e titânio apresentaram maiores valores de microdureza nos estados solubilizado e envelhecido. Por outro lado, medidas dilatométricas mostraram que há uma influência significativa tanto da composição química, quanto da taxa de aquecimento nas reações de precipitação e reversão da martensita para a austenita. No entanto, a transformação martensítica mostrou-se dependente apenas da taxa de aquecimento.Maraging steels are steels with a low carbon martensitic structure (BCC), which are hardened by precipitation of intermetallic phases. The aim of this work is to study the phase transformations of these steels: precipitation, martensite to austenite reversion and martensitic transformation. In this study, one cast of 300 grade and three casts of 350 grade were characterized using several complementary techniques: optical microscopy, scanning el ectron microscopy with energy dispersive analysis, microhardness, X-ray diffraction, ferritoscope and dilatometry. The results showed that the casts with higher concentrations of cobalt and titanium showed higher microhardness in the solution annealed and aged states. On the other hand, dilatometry measurements showed that there is a significant influence of both the chemical composition and the heating rate on the reactions of precipitation and reversion of martensite to austenite. However, the martensitic transformation was dependent solely on the heating rate.
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Hanemayer, Vincent C. (Vincent Cornelius) Carleton University Dissertation Engineering Civil. « Dilatometer tests using a model plate ». Ottawa, 1989.
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12
Ramírez, Mario Fernando González. « Influência da microestrutura nas propriedades mecânicas e na fragilização por hidrogênio em um aço microligado ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-19072013-170730/.
Texte intégralRésumé :
A tecnologia dos aços microligados para transporte de gás natural e petróleo tem sido pressionada pelo descobrimento das novas jazidas e o aumento da demanda no mundo. As solicitações ambientais e de resistência mecânica são os parâmetros para o desenvolvimento de aços de alta resistência baixa liga para o transporte de gás e petróleo a menor custo e de forma segura. Neste contexto esta pesquisa investiga, em um aço microligado para tubos API 5L X80, o efeito das transformações de fase obtidas por resfriamentos controlados na fratura induzida por hidrogênio Hydrogen Induced Cracking-(HIC) e nas propriedades mecânicas. Os testes de HIC foram realizados no material como recebido, na espessura da chapa submetida a resfriamentos contínuos e em amostras do material tratadas de forma a simular as regiões de grão grosso da zona afetada pelo calor (GGZAC). Segundo o ciclo de resfriamento, os aços microligados têm microestruturas complexas, como é caso do aço microligado em estudo, onde sua microestrutura, estudada em trabalhos anteriores, é formada principalmente por ferrita, bainita, perlita e microconstituinte austenita/martensita (AM). A morfologia, tamanho, quantidade e distribuição dos produtos de transformação na chapa mudam as propriedades do aço. Esses fenômenos são de grande interesse tecnológico em aços microligados para a fabricação de tubos soldados para o transporte de gás e petróleo, tanto quando a solda é realizada em campo como também durante o encurvamento por indução; aqui as propriedades mecânicas do tubo decorrentes do processo de fabricação termomecânico podem ser degradadas pela ação do aquecimento e dos resfriamentos experimentados na zona afetada pelo calor (ZAC), principalmente na região de GGZAC. A simulação dos ciclos térmicos para o estudo da HIC na espessura da chapa foram realizados em CP austenitizados a 900ºC e submetidos a resfriamentos contínuos no dilatômetro de têmpera. Para simular os ciclos térmicos com resfriamentos controlados focados na GGZAC e a seguir obter CP de tamanho adequado para testes de tração e Charpy, foi necessário fazer os tratamentos térmicos a 1300ºC e resfriamentos contínuos em um simulador termomecânico e dilatômetro Gleeble. O maior tamanho da amostra tratada termicamente neste último equipamento permitiu extrair amostras para avaliar as propriedades mecânicas e a HIC do material, pois as diferentes regiões da ZAC em uma solda real são restritas e não permitem este tipo de ensaios em uma região específica da ZAC. Os resultados permitiram identificar a suscetibilidade de cada microestrutura produto da transformação da austenita na espessura da chapa, sendo a região central da chapa a mais sensível ao hidrogênio no aço como recebido e quando tratado a baixas taxas de resfriamento de 0,5°C/s após austenitizado a 900°C. As bandas grosseiras formadas por estruturas de maior dureza que a matriz na região central diminuíram a resistência à HIC. Da mesma forma nos corpos de prova que simulam a região GGZAC, a fratura induzida pelo hidrogênio foi localizada na região central da espessura embora apresente bainita e ferrita acicular. A falha possivelmente se deve aos elementos remanescentes segregados nesta região central e partição de carbono para os sub contornos de grão da bainita e ferrita que cresceram a partir a austenita primária. As inclusões e precipitados, segundo seu tipo, forma e localização na microestrutura, participam ou não da nucleação e propagação da trinca, sendo a posição mais crítica quando localizadas dentro das estruturas bandeadas. Não foi observada a nucleação de trincas na presença de hidrogênio em precipitados de Nb e Ti.The technology of microalloyed steels for the transportation of natural gas and oil has been pressed by the discovery of new deposits and the increased demand in the world. Environmental requests for safety and ever increasing mechanical strength are the parameters for the development of high strength low alloy steels for transporting gas and oil at lower cost and safely. In this context, this research investigates, in a microalloyed steel pipe API 5L X80, the effect of phase transformations obtained by controlled cooling on the behavior when loaded with hydrogen - Hydrogen Induced Cracking - (HIC) and in the mechanical properties. HIC tests were performed on as-received material, on samples extracted from the thickness of the plate and subjected to continuous cooling and on samples of the material treated to simulate the coarse-grained regions of heat affected zone (CGHAZ). According to the cooling cycle, the microalloyed steels have complex microstructures: in the steel under evaluation its microstructure, studied in a previous work, consists mainly of ferrite, bainite, pearlite and austenite/martensite constituent (AM). The morphology, size, quantity and distribution of the products of transformation change the properties of plate steel. These phenomena are of great technological interest in microalloyed steels for the fabrication of welded tubes for the transport of gas and oil, when the welding is performed in the field as well as during hot bending; here the mechanical properties of the tube from the process of thermomechanical fabrication can be degraded by the action of heating and cooling experienced in the heat affected zone (HAZ), mainly in the region of CGHAZ. Simulations of thermal cycles for the study of HIC on sheet thickness were performed in coupons subjected to austenitization at 900ºC followed by continuous cooling in the dilatometer. To simulate the thermal cycles with controlled cooling, focused in the CGHAZ, and getting suitable sample sizes for tensile testing and Charpy, it was necessary to austenitize at 1300ºC followed by continuous cooling using the thermal and thermomechanical simulator in a Gleeble dilatometer. Samples heat treated in this equipment were suitable to evaluate the mechanical properties and the HIC of the material for different regions of HAZ, while a real weld would not have enough material to allow this type of testing on a specific region of HAZ. The results showed the susceptibility of each microstructure product of austenite transformation and of the position on the plate thickness. The central region of the plate was more sensitive to hydrogen in the steel as-received and when treated at low cooling rates of 0.5°C/s after austenitization at 900°C. The bands formed by coarse structures of greater hardness than the matrix in the central region decreased the resistance to HIC. Likewise in coupons that simulate the CGHAZ region, the fracture induced by hydrogen was located in the central thickness line, even when the microstructure were bainite and acicular ferrite. Failure there was possibly due to remnants of segregated elements in this central region and carbon partition to the subboundaries of the bainite and ferrite grain that grew from the primary austenite. Inclusions and precipitates, according to their type, shape and location in the microstructure, participating or not in the nucleation and propagation of the crack, were more critical when located within the banded structures; crack nucleation in the presence of hydrogen was not observed at Nb and Ti precipitates.
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Smith, Michael Gregory. « A laboratory study of the Marchetti dilatometer ». Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:91016f8e-e3b0-42d7-a51c-894ce0ff73ab.
Texte intégralRésumé :
The purpose of this study was twofold: to design, construct and commission a testing chamber for the calibration of in-situ devices in clay and to use the chamber to carry out a programme of research into the factors affecting the results of the Marchetti dilatometer test. A calibration chamber system was developed which was capable of producing one metre high by one metre diameter cylindrical beds of clay. The preparation technique involved an initial phase of one-dimensional consolidation in a rigid tube, followed by a second phase of consolidation in a chamber with independent stress control. The stress control was achieved through water-filled flexible membranes in the side and at the base of the chamber. Reasonably uniform distributions of the water content and the undrained strength were obtained from investigations carried out in each clay bed after they had been tested. The Marchetti dilatometer is an in-situ testing device the results of which have been interpreted chiefly through empirical correlations based on the results of field tests. The interpretation has mainly involved the use of two readings, and , though recently a third reading , has been introduced. Dilatometer tests were carried out in nine clay beds. The stress history and stress state of each clay bed were systematically varied in the test programme to allow their individual effects on the dilatometer readings to be assessed. The study revealed that in clay the dilatometer reading is controlled by the undrained strength and the horizontal stress and was independent of the degree of overconsolidation. Through use of this result it was shown that the applicability of many of the empirical correlations presently used to evaluate the dilatometer readings is restricted to deposits with one-dimensional stress histories. It was also found that was dependent on the undrained strength and that the reading was close to the total horizontal stress of the sample though the latter finding does not appear to be supported by the few field results that are available. The results have highlighted the redundancy of the reading for property evaluation. It was found that a timed sequence of , and readings could be used to detect the variation of the consolidation properties between clay beds. In addition to the tests in clay, the results of 31 dilatometer tests carried out in a calibration chamber for sand have also been analysed. An inter-relationship between , and was found suggesting that they were all measuring the same soil response; that of the pressure required to open a cavity in the sand. The reading was shown to be dependent on the horizontal stress and the state parameter, though this dependence could not be exploited to back calculate the horizontal stress. Overconsolidation of the sand specimens had no significant influence on the readings.
14
Peleška, Jan. « Kinetika koordinační polymerace 1-olefinů katalyzované diiminovými komplexy niklu ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-233353.
Texte intégralRésumé :
This Ph.D. thesis is focused on kinetic study of propene and hex-1-ene coordination polymerizations initiated by complex [(2-tBuC6H4)N=C(1,8-naphtalenediyl)C=N(2-tBuC6H4)]NiBr2 activated by simple organoaluminium compounds and on product properties. In first three parts proper activators are chosen in model polymerizations. The attention is paid to the reproducibility of polymerizations and analytical methods. The fourth part is focused on propene polymerization kinetics with the aim to define optimal reaction conditions, especially polymerization temperature and time. The four part concerns also properties of polymers. The fifth and sixth parts deal with hex-1-ene polymerization kinetics conducted at various activator/initiator molar ratios and various catalytic precursor concentrations, to find out kinetic orders with respect to catalyst and cocatalyst concentration. Last part is oriented on detail mechanistic investigation of nickel diimine complexes activation process. Results of measurements in presence or absence of monomer enabled to propose new interpretation of UV-vis spectra based on concrete structures of absorbing species.
15
Baier, Falko. « Atomare Leerstellen in Quasikristallen : eine spezifische Studie mit Positronen und Dilatometrie / ». [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9815627.
Texte intégral
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Britton, Karen J. « Automation of a capacitance dilatometer using distributed control ». Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/13975.
Texte intégralRésumé :
A comprehensive and novel system of automatic control has been designed and constructed using distributed intelligence techniques to control a complex item of equipment for the measurement of linear thermal expansion over the temperature range 1.5K - 300K. The system is designed to perform its own self-calibration automatically before the experiment commences. The low temperature dllatometer developed for this research project incorporates the most sensitive length change sensor available; a three-terminal capacitance transducer. This transducer technique has been refined to resolve length changes of 10-5A and more importantly, measure length against temperature profiles to better than 10-2A. The period of time required to collect a full set of data measurements on any particular specimen was in excess of 100 hours. Forming the heart of the automated control system is an assembly of Intel MCS-Sl single chip microcontrollers connected together on a serial link consisting of a simple pair of wires. The approach has been to divide the system automation into a number of specific control tasks and to allocate a different task to each controller. The Instrument has been used as a diagnostic tool to investigate the properties of lead glasses, and in particular to study the possibility of negative thermal expansion existing at low temperatures. Thermal expansion measurements were also performed to observe the phase change within single crystals of polydiacetylene and to research into low temperature phenomena occurlng within the crystal.
17
Mohapatra, Goutam. « Phase transformation kinetics the role of stress / ». [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-28837.
Texte intégral
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McPherson, Ian Duncan. « An evaluation of the flat dilatometer as an insitu testing device ». Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25116.
Texte intégralRésumé :
The results from the use of the dilatometer (Marchetti 1975, 1980) at 4 sites in British Columbia are presented. Comparisons are drawn between the dilatometer and other insitu test devices, including the piezo-friction cone, self-boring and Menard pressuremeters and field vane. Soils tested included saturated deltaic deposits, a sensitive plastic clay and a saturated, hydraulically placed fill.
Overall the dilatometer proved to be an extremely effective device. It had a low capital cost, required a minimum of support equipment and was simple to use. The data was repeatable and easily reduced using a computer programme. Computer output, both graphical and tabular, is easily amenable to interpretation to an engineer in the field.
For the most part the results in this thesis support Marchetti's empirical correlations with the following exceptions:
( i) determination of K0 in sands,
( ii) determination of a deformation modulus in clay,
and
(iii) in overconsolidated silts where it is believed that abnormal pore pressures caused the empirical correlations to breakdown.
The dilatometer is an insitu, total stress, penetration device which cannot be analysed in a fundamental manner. Elastic theory is inapplicable because of plastic straining during blade penetration and probably during membrane expansion. To more critically evaluate the dilatometer, the author designed an electronic research device with exactly the same external dimensions as Marchetti's dilatometer. The aim of the electronic dilatometer is to greatly improve understanding of the simple Marchetti dilatometer by allowing:
( i) a better understanding of the operational characteristics of Marchetti's dilatometer,
( ii) direct measurement of stress on, and deformation of, the membrane,
(iii) measurement of pore water pressure before and after halting penetration and during membrane expansion, and ( iv) measurement of the pushing force on the blade.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
19
Abbas, Naseeba. « Analysis of phase transformations in hydrogenated titanium metals by non-isothermal dilatometry ». Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/12339.
Texte intégralRésumé :
Includes bibliographical references (leaves 124-127).Hydrogen was used as a temporary alloying element in CP Ti and Ti-6AI-4V. The microstructural evolution and phase transformations were monitored, before, during and after hydrogenation with in-situ dilatometric testing. Wrought CP Ti and Ti-6AI-4V specimens were pre-annealed and experienced four consecutive thermal cycles (Cycles 1-4) i.e. hydrogenation, post-hydrogenation, dehydrogenation and post-dehydrogenation, during dilatometric testing. The specimen in each thermal cycle was heated to 1000°C, heating rate 1°C/min (with an isothermal hold at 1000°C for three hours for hydrogenation and dehydrogenation cycles) and then cooled to room temperature at cooling rate of 1°C/min.
20
Tsang, Clifford Hing-Cheung. « Research dilatometer testing in sands and in clayey deposits ». Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26749.
Texte intégralRésumé :
The development of Marchetti's flat dilatometer, method of testing, changes of Marchetti's (1980,1981) original correlations and Schmertmann's (1982,1983) proposed correlations are briefly described.
Factors affecting results of the dilatometer test (DMT) are discussed. In order to improve the understanding of the Marchetti dilatometer test (DMT), an electronic research dilatometer was developed at UBC. The research dilatometer can measure; pore pressure at the center of the membrane, membrane displacement, applied pressure, pushing force and verticality.
Test results obtained from the research dilatometer in sand and in clayey deposits at 4 sites in the Lower Mainland of B.C. are presented. Soil parameters interpretated using Marchetti's (1980,1981) and Schmertmann's (1982,1983) correlations are discussed. Comparison is made to other in-situ testing methods such as cone penetration test, vane shear test and pressuremeter test.
Based on a better understanding of the DMT, future potential methods of improving or checking the existing correlations are proposed.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
21
Neher, Roland. « Phasenbeziehungen und kinetische Modellierung von flüssigphasengesintertem SiC mit oxidischen und nitridischen Additiven ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-148121.
Texte intégralRésumé :
In the present dissertation the formation of microstructure, the kinetics of densification and the formation of surface layers developing during liquid phase sintering of silicon carbide are studied. The focus is on the additive systems Al2O3 plus Y2O3 and AlN plus Y2O3.
Phase and especially liquid phase formation in both of the systems SiC, Al2O3 , Y2O3 and AlN, Al2O3 , Y2O3 are investigated in detail examining 12 espectively 17 different compositions per system. Melting temperatures have been determined by TG/DTA, in both systems for the first time. Phase composition of samples was analysed by the combination of XRD, SEM and EDX. In the system SiC, Al2O3 , Y2O3 the formation of the phases expected from the quasibinary Al2O3 , Y2O3 could be observed thus silicon carbide has to be in equilibrium with the oxide additives. The low solubility of SiC in the oxide melt, which was suggested by Hoffmann and Nader, could be confirmed. In the system AlN, Al2O3 , Y2O3 the formation of phases as stated by Medraj was confirmed, except for the dimension of the stability region of the γ- spinel and YAG which is wider in the present work.
For the first time diffusion coefficients of the species Y3+ and Al3+ in the oxide melt formed by Al2O3 and Y2O3 at temperatures above 1825 ◦ C were determined. The values are in the order of 2 · 10−6 cm2 /s which results in a diffusion length of 14.1 μm for a diffusion time of one second. This allows the fast equilibration of Y and Al deficiencies.
Kinetics of densification was modeled by kinetic field, master curve and thermokinetic method, based on detailed experimental investigation of the shrinkage during liquid phase sintering of SiC. It could be proved that the first 30 − 40 % of densification are controlled by solid phase reactions which accelerate particle rearrangement without presence of a liquid phase. During the remaining 60 − 70 % of densification a liquid is present, resulting in the predominance of mechanisms of liquid phase sintering. The models deliver activation energies in the range from 608 KJ/mol to 1668 kJ/mol and allow, within the scope of validity of each method the prediction of densification during liquid phase sintering of silicon carbide.
When sintering silicon carbide with Al2O3 plus Y2O3 the formation of several surface layers, depending on atmosphere, maximum temperature, dwelling time and amount and composition of additives was observed. In nitrogen atmosphere with low partial pressures a surface layer consisting of AlN is forming whilst at high partial pressures SiAlON- polytypes occur. After sintering in Argon or Ar-CO- atmosphere three main types of surface layers are present. One consists of alumina, one contains only YAG and one shows highly porous, additive depleted regions. An explanation for the formation of the several surface layers could be given by the combination of the determined diffusion coefficients with the results achieved in the thermodynamics part.
The results achieved in this work can be a contribution to the knowledge based design of the production process of liquid phase sintering of silicon carbide.
22
Ruiz, Alberto Ibañez. « A presença do nióbio em um ferro fundido branco de cromo-molibdênio : traçado da curva transformação-tempo-temperatura ». Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/18/18136/tde-09102017-142618/.
Texte intégralRésumé :
Avaliou-se experimentalmente o ferro fundido branco de alto-cromo-molibdênio ao qual foi adicionado nióbio, a respeito de sua temperabilidade. Dilatometricamente traçou-se a curva TTT desse material, bem como a de um ferro fundido branco de alto cromo para efeito comparativo. Constatou-se por essa comparação e pelos resultados da literatura a alta temperabilidade obtida pela liga experimental. A partir da temperatura de austenitização utilizada, podem-se usar taxas de resfriamento de até 0,12°C/s sem transformação de fase, enquanto que na liga comparativa essa taxa aumenta para 5,8°C/s. Foram realizadas análises de desgaste abrasivo, de dureza e microdureza, de difração por raios-X , de fase magnética e de microanálise como forma de caracterizar as transformações de fase observadas por dilatometria. As variações estruturais decorrentes dos tratamentos térmicos realizados nas duas ligas foram acompanhados por microscopia ótica. É indicativo pelo presente trabalho que tal material além de suas características inerentes de resistência à abrasão e à corrosão oferece maior flexibilidade nos projetos que envolvam paredes espessas.In this work we studied the hardenability of high chromium- molibdenum white cast iron with niobium. By dilatometry we obtained the TTT curve of this material as well as the high chromium white cast iron for comparison. This comparison and available results in literature confirm the high temperability of experimental material. We can use slow rate cooling 0,12°C/s or higher without phase transformation, while in the comparative alloy this rate is around 5,8°C/s or higher from specific used austenitic abrasive temperature. We also realized analysis of abrasive wear, hardness and microhardness, raios-X difraction, magnetic phase and microanalyse for verifing the phase transformation as observed by dilatometry. The structure variation as function of termic treatment in both alloys is monitored by optical microscope. The present work indicate that the material under study can offer more flexibility for projects with thick materials apart from intrinsic characteristics of abrasive wear and corrosion.
23
Spannagel, Ruven [Verfasser], Claus [Akademischer Betreuer] Braxmaier, Calus [Gutachter] Braxmaier et Andreas [Gutachter] Rittweger. « Laser-interferometric dilatometry / Ruven Spannagel ; Gutachter : Calus Braxmaier, Andreas Rittweger ; Betreuer : Claus Braxmaier ». Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1141862026/34.
Texte intégral
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Mohamadian, Wrya. « DILATOMETRIC EVALUATION OF SOME CRITICAL PHYSICAL PROPERTIES OF OT75 AND OT101 STEEL GRADES ». Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86758.
Texte intégralRésumé :
Due to its hardness, martensite, perhaps, is the most desirable structure, but at the same time, martensite is very brittle. Balancing between hardness and brittleness is a challenge that steel manufacturers must deal with it. To decrease brittleness and to solve this problem, designers purposely temper the steel. Heat treatment, e.g., slowing down the quenching quota/rate, will form a procedure of martensite formation incomplete phase and consequently a mixture of austenite-martensite. Tempering is another alternative to operate on martensite and make it malleable without losing hardness and preventing brittleness. As its seen, the heat treatment for controlling the mechanical chemical property is crucial. Managing the critical temperature, A1, A3, and Ms) during martensite formation, which influences the transformation process, must be considered. The Prior Austenite Grain Size also has been measured. This project has examined the critical temperature for three wire steel specimens to determine the martensite start temperature (Ms), microstructure, and hardness. The project has mainly used dilatometry. Besides that, light optical microscopy (LOM), hardness measurement of specimens, and empirical equations for determining the critical temperatures have been used. This work has been made up of two main parts: literature review and experimental work/ project procedure.
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Chiu, Chung-fai. « A modified flat dilatometer for field measurement of non-linear soil behaviour at small strains / ». Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1806176X.
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Rivera, Cruz Ivan. « An evaluation of seismic flat dilatometer and lateral stress seismic piezocone ». Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/3890.
Texte intégralRésumé :
The flat dilatometer (DMT) and piezocone penetration (CPTU) tests are likely to be among the most
widely used in situ testing methods for soil characterization and indirect determination of geotechnical
design parameters such as: strength, stiffness, permeability and compressibility. The flat dilatometer has
proved to be a reliable, robust and adaptable tool, and the data obtained with this instrument is very
repeatable, and easy to reduce and process. Furthermore, the addition of a seismic module to the standard
flat dilatometer (SDMT) to measure the shear wave velocity (Vs) significantly complements the set of
data typically obtained with a standard DMT test. Nonetheless, the experience in interpreting the
combination between Vs and DMT data is fairly limited due to the recent introduction of the SDMT for
commercial applications. Additionally, the estimation of the coefficient of earth pressure at rest (K₀) has
been the most important application of the DMT since its introduction. However, a potential weakness of
the DMT is that the derivation of K₀ is based upon empirical correlations developed some time ago and
neither improvement work nor upgrade of these approaches has been performed in the last 10 years.
Throughout the years several additional sensors have been developed in order to supplement the data
collected with the CPTU test. Among the wide variety of sensor developed, the lateral stress module
mounted behind a piezocone represents a promising tool for estimation of in situ lateral stress conditions
from the interpretation of lateral stress penetration data. However, the popularity of the so called lateral
stress cone has declined over the years due to constraints in both the instrumentation and the
interpretation of measured data. Also, the application of this instrument remains limited to specific soils
conditions and specific projects. However, the valuable experience gained throughout the years in the
development and application of several lateral stress cones in combination with developments in
electronics and understanding of soil behaviour allow the improvement of this type of technology.
This thesis presents the results of a comprehensive laboratory and field testing programs performed by the
author at several research sites located in the Lower Mainland of BC, undertaken in order to assess the
performance of the seismic flat dilatometer and lateral stress seismic piezocone (LSSCPTU), built and
develop at UBC. Firstly, the analysis of field measurements with the SDMT collected at several sites have
demonstrated the potential for an improved soil characterization through the combination of DMT
parameters and the small strain shear modulus (G₀). Additionally the usefulness of the DMT-C closing
pressure for soil identification is shown. On the basis of several relationships identified from this data, a
new soil type behaviour system based upon SDMT measurements is proposed. Furthermore, empirical
correlations based upon fairly large and updated databases have been developed to estimate K₀ and Vs
values from DMT parameters.
27
Udakara, Deepthi De Silva. « Experimental study of a modified flat dilatometer under plane strain condition ». Thesis, Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22089007.
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Pool, Randal Gleason. « Rational framework for interpreting overconsolidation ratio, undrained strength ratio, and lateral stress coefficient from flat dilatometer tests in clay ». Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/32768.
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趙仲輝 et Chung-fai Chiu. « A modified flat dilatometer for field measurement of non-linear soil behaviour at small strains ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212992.
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Ferreira, Anelise Rodolfo [UNESP]. « Estudo da dilatometria do titânio e das expansões de presa e térmica de revestimentos fosfatados ». Universidade Estadual Paulista (UNESP), 2004. http://hdl.handle.net/11449/97297.
Texte intégralRésumé :
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ferreira_ar_me_arafo.pdf: 853886 bytes, checksum: ac8807532f1213d7b8e8c7e98c2c8cb4 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O estudo avaliou a expansão térmica dos materiais metálicos titânio c.p. (RMI Company, Ohio, EUA), Co-Cr-Mo-W (Dentaurum, Pforzhem, Alemanha) e Ni-Cr (Dentaurum, Pforzhem, Alemanha) para estimar a contração de fundição do titânio e determinou a expansão de presa e térmica dos revestimentos fosfatados Rematitan Plus (Dentaurum, Pforzhem, Alemanha), específico para titânio e Rema Exakt (Dentaurum, Pforzhiem, Alemanha) e Castorit Super C (Dentaurum, Pforzhem, Alemanha). Cada concentração de líquido especial foi variada na proporção de (100%, 75% e 50%) de água destilada, com o objetivo de determinar em que concentração de líquido e em que temperatura a somatória da expansão de presa e térmica seriam suficientes para compensar a contração estimada. Para a dilatometria dos metais padrões de cera com 14 mm de altura e 7 mm de diâmetro foram obtidos a partir de um padrão metálico, em seguida, montados em base formadora de cadinho com o conduto de alimentação e incluídos com cada revestimento na concentração de 100%. Os padrões foram incluídos e aquecidos no forno EDG (EDG - Equipamentos, São Carlos, SP). O Ti c.p. foi fundido na máquina Discovery - Plasma (EDG - Equipamentos, São Carlos, SP), e as outras ligas a fundição ocorreu em máquina de fundição centrífuga convencional. Após o polimento, os corpos de prova foram analisados e a expansão térmica foi registrada no Dilatômetro DIL 409 (Netzch) em atmosfera de ar, numa taxa de aquecimento de 10ºC/min. O Ti c.p. foi aquecido até 1550ºC, o Co-Cr-Mo-W até 1160ºC e o Ni-Cr até 1090ºC. Para a medida da expansão de presa, os revestimentos foram misturados com líquido especial e vertidos no molde de silicone (Siqmol) com cavidade de 50 mm X 10 mm X 10 mm. Uma lâmina de vidro e o apalpador (Tesa)...
This study evaluated the thermal expansion of the metallic materials titanium c.p. (RMI Company, Ohio, USA), Co-Cr-Mo-W (Dentaurum, Pforzhem, Germany) and Ni-Cr-Mo (Dentaurum, Pforzhem, Germany) to estimate the casting shrinkage of titanium and determine the setting and thermal expansion of phosphate-bonded investment materials. This investment used were Rematitan Plus (Dentaurum, Pforzhem, Germany), specific for titanium, Rema Exakt (Dentaurum, Pforzhem, Germany) and Castorit Super C (Dentaurum, Pforzhem, Germany). Each concentration of special liquid/distilled/water was varied in which ratio by 100%, 75% and 50%. This aim of this study was to determine what liquid concentration and temperature the overall expansion could be enough to compensate the casting shrinkage. For the dilatometry of the metals, wax patterns (14 mm X 7 mm) were made, attached to sprue, mounted in and mounted on crucible formers and included in 100% of special liquid. The invested patterns were heated in a burnout EDG (EDE - São Carlos - Brazil). Ti c.p. was casting in the machine Discovery - Plasma (EDG - Equipments, São Carlos, SP), and the other alloys were casting in a conventional centrifugal casting machine. After polishing, the samples were analyzed and the thermal expansion was recorded in the equipment Dilatômetro DIL 409 (Netzch) in air's atmosphere, in a rate of heating of 10ºC/min. The Ti c.p. was heated up to 1550ºC, the Co-Cr-Mo-W up to 1160ºC and Ni-Cr-Mo up to 1090ºC. For measurement of the vertical setting expansion, those investments were mixed with special liquid and invested into silicone moulds of the metal pattern (50 mm x 10 mm x 10 mm). A glass plate and dial gauge were seated on the sample, and after two hours the setting expansion was measured (Se). The distance between the ends (De)...(Complete abstract, click electronic access below)
31
Ferreira, Anelise Rodolfo. « Estudo da dilatometria do titânio e das expansões de presa e térmica de revestimentos fosfatados / ». Araraquara : [s.n.], 2004. http://hdl.handle.net/11449/97297.
Texte intégralRésumé :
Orientador: Gelson Luis AdaboBanca: Renata Garcia Fonseca
Banca: Ricardo Faria Ribeiro
Resumo: O estudo avaliou a expansão térmica dos materiais metálicos titânio c.p. (RMI Company, Ohio, EUA), Co-Cr-Mo-W (Dentaurum, Pforzhem, Alemanha) e Ni-Cr (Dentaurum, Pforzhem, Alemanha) para estimar a contração de fundição do titânio e determinou a expansão de presa e térmica dos revestimentos fosfatados Rematitan Plus (Dentaurum, Pforzhem, Alemanha), específico para titânio e Rema Exakt (Dentaurum, Pforzhiem, Alemanha) e Castorit Super C (Dentaurum, Pforzhem, Alemanha). Cada concentração de líquido especial foi variada na proporção de (100%, 75% e 50%) de água destilada, com o objetivo de determinar em que concentração de líquido e em que temperatura a somatória da expansão de presa e térmica seriam suficientes para compensar a contração estimada. Para a dilatometria dos metais padrões de cera com 14 mm de altura e 7 mm de diâmetro foram obtidos a partir de um padrão metálico, em seguida, montados em base formadora de cadinho com o conduto de alimentação e incluídos com cada revestimento na concentração de 100%. Os padrões foram incluídos e aquecidos no forno EDG (EDG - Equipamentos, São Carlos, SP). O Ti c.p. foi fundido na máquina Discovery - Plasma (EDG - Equipamentos, São Carlos, SP), e as outras ligas a fundição ocorreu em máquina de fundição centrífuga convencional. Após o polimento, os corpos de prova foram analisados e a expansão térmica foi registrada no Dilatômetro DIL 409 (Netzch) em atmosfera de ar, numa taxa de aquecimento de 10ºC/min. O Ti c.p. foi aquecido até 1550ºC, o Co-Cr-Mo-W até 1160ºC e o Ni-Cr até 1090ºC. Para a medida da expansão de presa, os revestimentos foram misturados com líquido especial e vertidos no molde de silicone (Siqmol) com cavidade de 50 mm X 10 mm X 10 mm. Uma lâmina de vidro e o apalpador (Tesa)...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study evaluated the thermal expansion of the metallic materials titanium c.p. (RMI Company, Ohio, USA), Co-Cr-Mo-W (Dentaurum, Pforzhem, Germany) and Ni-Cr-Mo (Dentaurum, Pforzhem, Germany) to estimate the casting shrinkage of titanium and determine the setting and thermal expansion of phosphate-bonded investment materials. This investment used were Rematitan Plus (Dentaurum, Pforzhem, Germany), specific for titanium, Rema Exakt (Dentaurum, Pforzhem, Germany) and Castorit Super C (Dentaurum, Pforzhem, Germany). Each concentration of special liquid/distilled/water was varied in which ratio by 100%, 75% and 50%. This aim of this study was to determine what liquid concentration and temperature the overall expansion could be enough to compensate the casting shrinkage. For the dilatometry of the metals, wax patterns (14 mm X 7 mm) were made, attached to sprue, mounted in and mounted on crucible formers and included in 100% of special liquid. The invested patterns were heated in a burnout EDG (EDE - São Carlos - Brazil). Ti c.p. was casting in the machine Discovery - Plasma (EDG - Equipments, São Carlos, SP), and the other alloys were casting in a conventional centrifugal casting machine. After polishing, the samples were analyzed and the thermal expansion was recorded in the equipment Dilatômetro DIL 409 (Netzch) in air's atmosphere, in a rate of heating of 10ºC/min. The Ti c.p. was heated up to 1550ºC, the Co-Cr-Mo-W up to 1160ºC and Ni-Cr-Mo up to 1090ºC. For measurement of the vertical setting expansion, those investments were mixed with special liquid and invested into silicone moulds of the metal pattern (50 mm x 10 mm x 10 mm). A glass plate and dial gauge were seated on the sample, and after two hours the setting expansion was measured (Se). The distance between the ends (De)...(Complete abstract, click electronic access below)
Mestre
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Neal, Patrick M. « Correlation of liquefaction and settlement in windblown sands using the flat plate dilatometer ». Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1032.
Texte intégralRésumé :
A thesis submitted to the Faculty of Engineering, Cape Peninsula University of Technology, Cape
Town, in partial fulfilment of the requirements for the M-Tech Degree in Civil Engineering”
Cape Town
16 MAY 2011Dwellings in impoverished and upper class urban areas of the Western Cape have undergone serious structural failure due to problematic underlying sand deposits, generally known as Cape Flats windblown found in areas such as Delft, Blue Downs and the Atlantic Beach Golf Estate. The problem is compounded further when moisture penetrates below the footings and reaches saturation in the winter months. When poorly graded sand with a high fines content is coupled with vibration (through earth tremors), liquefaction may occur and without proper precautions, this can lead to inadequate foundation design, more than expected settlement and eventual structural failure. Some sand deposits are highly contaminated with organic debris, leading to compressible and collapsible conditions. Little knowledge is locally available of liquefiable conditions in windblown dune sand and what long-term settlement can be expected. The Western Cape is not known as an area exposed to serious seismic activity, but an updated (and more locally applicable set of data) is needed to eliminate possible erroneous foundation design. Samples have been extracted from typical sandy sites in the Western Cape where windblown dune sand is evident. Laboratory tests have been carried out on representative samples for closer examination and have been placed inside a purpose built calibration chamber that facilitates easy densification and probe testing. A DMT (flat blade dilatometer) was used to hydraulically penetrate the chamber sand sample to varying depths (up to 800 mm). The device can measure (with reduction formula) horizontal stress, angle of friction, bearing capacity and settlement. An accelerometer was attached to the chamber wall and vibration measured with the sand in varying states of moisture. The DMT is an unexplored in-situ soil testing device in South Africa and so far the outcome indicates favourably compared to other devices such as the Dynamic Cone Penetrometer (DCP. The DMT has the ability to measure the in-situ stiffness, strength and stress history parameters of soil for better site characterisation. Settlement within the chamber is easily measured. The DMT has, for example, indicated that sand from the Philippi area are a problematic founding soil and should be treated with special care at shallow founding levels. The horizontal stress index is low and according to the available knowledge on soil stress history, these sand, coupled with low densities, can liquefy easily and result in structural damage. The West Coast dune sand, being coarser and easily consolidated, poses less of a problem under liquefiable conditions. A suitable terrain device for easy on-site manoeuvrability is required to assist the DMT in further testing.
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Vilela, Rivelino Cunha. « Estudo de transições de fase em cristais de l-alanina + ácido oxálico ». reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/13883.
Texte intégralRésumé :
VILELA, Rivelino Cunha. Estudo de transições de fase em cristais de l-alanina + ácido oxálico. 2013. 113 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013.Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-29T21:51:24Z No. of bitstreams: 1 2013_tese_rcvilela.pdf: 12577577 bytes, checksum: 4dc32419c1bbdde79375612c04227181 (MD5)
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In the present word we have studied the effect of temperature on the Raman spectra of crystals of L-alanine + oxalic acid, C3H8NO2+.C2HO4-. Raman spectroscopy measurements were performed on polycrystalline samples at different temperatures varying in the range from room temperature to T = 20 K; a tentative assignment of all normal modes was furnished. In order to help the understanding of the crystal behavior we have also obtained X-ray diffractograms and studied the dependence of lattice parameters through dilatometry as a function of temperature in the 290 K – 93 K range. The three different techniques allowed us to construct a picture of the material under low temperature conditions. As a consequence we have realized that L-alanine + oxalic acid crystal undergoes three phase transitions at low temperatures. The splitting of a band at 90 cm-1 and an anomaly in one of the lattice parameters are the signature for the first phase transition that is observed at 250 K. At 150 K it was observed the appearance of two new bands in the Raman spectrum and, simultaneously, it was observed change in the curves of a and c lattice parameters. Additionally, it was verified the appearance of new peaks in the X-ray diffractogram at the same temperature, characterizing the second phase transition. At a temperature even lower, at about 43 K, it was verified the occurrence of the third phase transition that has as main characteristic the splitting of two bands that are associated to the lattice modes. Changes in the modes associated with CH3 and NH3+ during the cooling is discussed. An important behavior of the crystal with the cooling process was the red shift of the band of lower frequency, similar to the soft-mode vibration of ferroelectric materials, although the frequency of the mode in L-alanine + oxalic acid does not goes to zero. Based on the results on Raman spectroscopy, dilatometry and X-ray diffraction, and on the possible symmetry sites occupied by the molecules through the O=CC group in the various phases, it is suggested the following sequence of phase transitions D24 C2h5 Cs3 C23, which should occur at 250 K, 150 K and 43 K.
Neste trabalho, estudou-se o efeito da temperatura nos espectros Raman de cristais de L-alanina + ácido oxálico, C3H8NO2+.C2HO4-. Foram realizadas medidas de espectroscopia Raman em policristais a diferentes temperaturas no intervalo compreendido entre a temperatura ambiente e a temperatura de 20 K, sendo fornecida uma identificação tentativa para todos os modos normais de vibração observados. Para auxiliar o entendimento do comportamento do cristal também foram obtidos os difratogramas de raios-X bem como estudada a dependência dos parâmetros de rede em função da temperatura através de dilatometria no intervalo entre 290 K e 93 K. As três técnicas utilizadas em conjunto permitiram mostrar o comportamento estrutural do material em baixas temperaturas. Deste quadro foi possível inferir que os cristais de L-alanina + ácido oxálico apresentam três diferentes transições de fase durante o resfriamento. Em 250 K o aparecimento de um dubleto em 90 cm-1 e a anomalia num dos parâmetros de rede apontam para a ocorrência da primeira transição de fase. Em 150 K surgem pelo menos duas novas bandas no espectro Raman, ao mesmo tempo em que ocorrem bruscas mudanças de inclinação nas curvas que representam as dimensões dos eixos a e c do cristal. Também se verifica que, de forma semelhante ao que ocorre com os espectros Raman, aparecem novos picos no difratograma de raios-X em torno desta temperatura, caracterizando assim a segunda transição de fase. A uma temperatura ainda mais baixa, em torno de 43 K, foi verificada a ocorrência da terceira transição de fase, que tem como principal característica a separação de dois modos Raman associados a modos da rede. Mudanças nos ambientes dos grupos CH3 e do NH3+ durante o resfriamento são discutidas. Um importante aspecto apresentado pelos espectros Raman com o resfriamento da amostra foi o deslocamento da banda de mais baixa energia para menores valores de frequências, semelhantemente ao que ocorre com vibrações do tipo soft-mode em materiais ferroelétricos, embora a frequência do modo no cristal de L-alanina + ácido oxálico não tenha ido à zero. Baseado nos resultados acima e nos possíveis sítios de simetria ocupados pelas moléculas através do grupo O=CC nas diversas fases, sugere-se a seguinte sequência de transições de fase D24 para C2h5 para Cs3 para C23, que aconteceriam, respectivamente, nas temperaturas de 250 K, 150 K e 43 K.
34
Agarwal, Gaurav. « Fabrication of ZnO varistor-based gas sensors using a novel rate controlled sintering dilatometer ». Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12927.
Texte intégral
35
Balzer, Christian [Verfasser], Vladimir [Gutachter] Dyakonov et Oskar [Gutachter] Paris. « Adsorption-Induced Deformation of Nanoporous Materials — in-situ Dilatometry and Modeling / Christian Balzer ; Gutachter : Vladimir Dyakonov, Oskar Paris ». Würzburg : Universität Würzburg, 2018. http://d-nb.info/1151818690/34.
Texte intégral
36
Mulder, Riaan. « Volumetric change due to polymerization in dental resins as measured with an electronic mercury dilatometer ». Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/4304.
Texte intégralRésumé :
Magister Scientiae Dentium - MSc(Dent)To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. The volumetric change that occur during the polymerization of dental composite restorations are considered to be one of the most significant contributing factors when considering the failure in composite restorations. Volumetric shrinkage of more than 2% is considered to be enough to result in the occurrence of secondary caries resulting in fracture of restorations and failure in the adhesive layer of a resin restoration. The total volumetric change of dental resins can be attributed to three main factors: Firstly, the polymerization reaction that results in the formation of a polymer chain. Secondly, the increase of the exothermic thermal effects produced by the polymerization reaction and thirdly, light irradiance energy that is transferred to the dental resin.
37
Kates, Gina L. « Development and implementation of a seismic flat dilatometer test for small-and high-strain soil properties ». Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/20234.
Texte intégral
38
Feng, Kai. « Development of a dilatometer and mass spectrometer system for studying gas phase reactions during sintering / ». free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074400.
Texte intégral
39
Matusch, Dirk. « Phasenuntersuchungen im System Y-Si-Al-O-N ». Stuttgart : Univ., Max-Planck-Institut für Metallforschung, 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10727646.
Texte intégral
40
Neekhra, Siddharth. « A new mineralogical approach to predict coefficient of thermal expansion of aggregate and concrete ». Texas A&M University, 2004. http://hdl.handle.net/1969.1/1461.
Texte intégralRésumé :
A new mineralogical approach is introduced to predict aggregate and concrete coefficient
of thermal expansion (CoTE). Basically, a modeling approach is suggested based on the
assumption that the CoTE of aggregate and concrete can be predicted from the CoTE of
their constituent components. Volume percentage, CoTE and elastic modulus of each
constituent mineral phase are considered as input for the aggregate CoTE model, whereas
the same properties for coarse aggregate and mortar are considered for the concrete CoTE
model. Methods have been formulated to calculate the mineral volume percentage from
bulk chemical analysis for different type of rocks commonly used as aggregates in Texas.
The dilatometer testing method has been established to measure the CoTE of aggregate,
pure minerals, and concrete. Calculated aggregate CoTE, based on the determined CoTE
of pure minerals and their respective calculated volume percentages, shows a good
resemblance with the measured aggregate CoTE by dilatometer. Similarly, predicted
concrete CoTE, based on the calculated CoTE of aggregate and mortar and their
respective volume percentages compares well with the measured concrete CoTE by
dilatometer. Such a favorable comparison between predicted and measured CoTE
provided a basis to establish the composite model to predict aggregate and concrete
CoTE. Composite modeling will be useful to serve as a check of aggregate source
variability in terms of quality control measures and improved design and quality control
measures of concrete.
41
Gentile, Paul Steven. « Development of a novel high performance electrolyte supported solid oxide fuel cell ». Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/gentile/GentileP1207.pdf.
Texte intégral
42
Akbar, Aziz. « Development of low cost in-situ testing devices ». Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364801.
Texte intégral
43
Shon, Chang Seon. « Performance-based approach to evaluate alkali-silica reaction potential of aggregate and concrete using dilatometer method ». [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2694.
Texte intégral
44
Conti, Elaine Cristina Guerbach [UNESP]. « Estudo da interface titânio/porcelana, com três porcelanas de ultra baixa fusão, empregando-se microscopia eletrônica de varredura e dilatometria ». Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/89679.
Texte intégralRésumé :
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conti_ecg_me_arafo.pdf: 2274247 bytes, checksum: bd8fd8849fb076ead7d056ec179f83a2 (MD5)O objetivo deste trabalho foi caracterizar química e metalograficamente o Ti.c.p. antes e após a fundição por Plasma-Skull, e estudar as interfaces entre esse metal e as porcelanas Vitatitankeramik, Triceram e Noritake TI22, empregando-se M.E.V., EDS, Mapeamento Elementar e Dilatometria. Trinta e cinco placas nas dimensões de 25mm x 3mm x 1mm foram fundidas pela máquina nacional Discovery - Plasma, EDG Equipamentos, sendo 5 amostras empregadas para a análise química e metalográfica e as 30 restantes, utilizadas para aplicação das porcelanas, sendo divididas em 3 grupos de 10 placas cada. O tratamento da superfície do metal, bem como a aplicação e as cocções das porcelanas foram realizadas segundo as recomendações de cada fabricante. Posteriormente, as amostras tiveram uma de suas faces laterais lixadas, até a exposição da interface e preparadas para análise por M.E.V. Para os ensaios de Dilatometria, 2 amostras de Ti c.p. e 2 para cada sistema de porcelanas foram confeccionadas na forma de cilindro com 12 mm de comprimento x 2 mm de diâmetro, e em cada amostra foi soldado um termopar de cromel-alumel, para medida de temperatura dos ensaios. As curvas de expansão térmica do Ti c.p. e das três porcelanas, foram levantadas para estudar a compatibilidade entre os conjuntos metalocerâmicos. Os resultados da análise química e das imagens obtidas por Microscopia Óptica, demonstram que o Ti c.p. após a fundição apresenta condições físico-químicas adequadas para receber a aplicação da porcelana. Dos resultados de M.E.V., observa-se que todos os sistemas apresentaram integridade nas interfaces Ti/Bonder, livre de fendas ou poros, com um bom contato entre a porcelana e o metal, confirmado pelas imagens do Mapeamento Elementar, sugerindo uma adequada interação entre esses materiais. Da análise das imagens do EDS... .
The aim of this work was to perform a chemical na metalographical characterization of the commercially pure titanium before and after melting by the Plasma-Skull method, and to study the interfaces between this metal and the porcelains Vitatitankeramik, Triceram e Noritake TI22, using SEM, EDS, elementary mapping and dilatometry. Thirty five samples with dimensions 25mm x 3mm x 1mm were melted in a national Discovery-Plasma, EDG Equipaments, five of which were used for chemical analysis and metalography and the remaining thirty, divided in three groups, were used for applications of the porcelains. The metal surface treatment, as well as the applications and firing of the porcelains, were performed according to the recommendations of each manufacturer. Subsequently, one of the lateral surfaces of the samples was polished until the interfaces was exposed and then was prepared for the SEM analysis. Two samples of commercially pure titanium and other two for each system of porcelains were cylindrically shaped with lengths of 12mm and 2mm of diameter, and in each sample Chromel-Alumel thermocouple was welded to measure the temperature of the tests. The thermal expansion curves of the commercially pure titanium and porcelains were measured to study the compatibility of the metal-ceramic systems. The chemical analysis and optical microscopy results show that the commercially pure titanium after the melting exhibits appropriate physical and chemical conditions for the application of the porcelain. The SEM results indicate that all the systems exhibits integrity of the Ti/bonder interface, free of gap and porous, with good contact between metal and porcelain, which was confirmed by the elementary mapping images, suggesting and adequate interaction between these materials. From the analysis of the EDS images... (Complete abstract, click electronic address below).
45
Conti, Elaine Cristina Guerbach. « Estudo da interface titânio/porcelana, com três porcelanas de ultra baixa fusão, empregando-se microscopia eletrônica de varredura e dilatometria / ». Araraquara : [s.n.], 2002. http://hdl.handle.net/11449/89679.
Texte intégralRésumé :
Resumo: O objetivo deste trabalho foi caracterizar química e metalograficamente o Ti.c.p. antes e após a fundição por Plasma-Skull, e estudar as interfaces entre esse metal e as porcelanas Vitatitankeramik, Triceram e Noritake TI22, empregando-se M.E.V., EDS, Mapeamento Elementar e Dilatometria. Trinta e cinco placas nas dimensões de 25mm x 3mm x 1mm foram fundidas pela máquina nacional Discovery - Plasma, EDG Equipamentos, sendo 5 amostras empregadas para a análise química e metalográfica e as 30 restantes, utilizadas para aplicação das porcelanas, sendo divididas em 3 grupos de 10 placas cada. O tratamento da superfície do metal, bem como a aplicação e as cocções das porcelanas foram realizadas segundo as recomendações de cada fabricante. Posteriormente, as amostras tiveram uma de suas faces laterais lixadas, até a exposição da interface e preparadas para análise por M.E.V. Para os ensaios de Dilatometria, 2 amostras de Ti c.p. e 2 para cada sistema de porcelanas foram confeccionadas na forma de cilindro com 12 mm de comprimento x 2 mm de diâmetro, e em cada amostra foi soldado um termopar de cromel-alumel, para medida de temperatura dos ensaios. As curvas de expansão térmica do Ti c.p. e das três porcelanas, foram levantadas para estudar a compatibilidade entre os conjuntos metalocerâmicos. Os resultados da análise química e das imagens obtidas por Microscopia Óptica, demonstram que o Ti c.p. após a fundição apresenta condições físico-químicas adequadas para receber a aplicação da porcelana. Dos resultados de M.E.V., observa-se que todos os sistemas apresentaram integridade nas interfaces Ti/Bonder, livre de fendas ou poros, com um bom contato entre a porcelana e o metal, confirmado pelas imagens do Mapeamento Elementar, sugerindo uma adequada interação entre esses materiais. Da análise das imagens do EDS... (Resumo completo, clicar acesso eletrônico abaixo).Abstract: The aim of this work was to perform a chemical na metalographical characterization of the commercially pure titanium before and after melting by the Plasma-Skull method, and to study the interfaces between this metal and the porcelains Vitatitankeramik, Triceram e Noritake TI22, using SEM, EDS, elementary mapping and dilatometry. Thirty five samples with dimensions 25mm x 3mm x 1mm were melted in a national Discovery-Plasma, EDG Equipaments, five of which were used for chemical analysis and metalography and the remaining thirty, divided in three groups, were used for applications of the porcelains. The metal surface treatment, as well as the applications and firing of the porcelains, were performed according to the recommendations of each manufacturer. Subsequently, one of the lateral surfaces of the samples was polished until the interfaces was exposed and then was prepared for the SEM analysis. Two samples of commercially pure titanium and other two for each system of porcelains were cylindrically shaped with lengths of 12mm and 2mm of diameter, and in each sample Chromel-Alumel thermocouple was welded to measure the temperature of the tests. The thermal expansion curves of the commercially pure titanium and porcelains were measured to study the compatibility of the metal-ceramic systems. The chemical analysis and optical microscopy results show that the commercially pure titanium after the melting exhibits appropriate physical and chemical conditions for the application of the porcelain. The SEM results indicate that all the systems exhibits integrity of the Ti/bonder interface, free of gap and porous, with good contact between metal and porcelain, which was confirmed by the elementary mapping images, suggesting and adequate interaction between these materials. From the analysis of the EDS images... (Complete abstract, click electronic address below).
Orientador: José Roberto Cury Saad
Coorientador: Antônio Carlos Guastaldi
Banca: Marcelo Ferrarezi de Andrade
Banca: Silvio José Mauro
Mestre
46
Silva, Cloir Salatiel da. « Análise microestrutural em altas temperaturas de um ferro fundido branco de alto cromo com molibdênio e nióbio ». Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-14092016-124243/.
Texte intégralRésumé :
As mudanças microestruturais, causadas pela adição de elementos de liga e pelos tratamentos térmicos, modificam as propriedades mecânicas e tribológicas dos materiais. Foi desenvolvido então um estudo em amostras de um ferro fundido branco de alto cromo com molidbênio e nióbio, procurando determinar os efeitos dos elementos de liga molibdênio e nióbio, na microestrutura deste material, através de medidas de dureza, dilatometria, ataque químico, microscopia eletrônica de varredura e,principalmente, a utilização de metalografia em altas temperaturas. A técnica de metalografia em altas temperaturas permite o estudo das mudanças microestruturais durante os ciclos térmicos, que foram programados, tendo como referência a curva TTT previamente traçada para este material, focalizando regiões onde não ocorrem mudanças de fase. Deste modo foram obtidas as aparências metalográficas em altas temperaturas e feito um estudo comparativo com as outras técnicas usadas. Com isto é possível melhorar o conhecimento sobre a microestrutura do material em questão e obter ligas com propriedades pré-determinadas.The microstructural changes caused by the addition of alloying elements and by thermal treatments modify the mechanical and tribological properties of the materials. A study was develop on samples of molybdenum and niobium high chromium white cast iron, trying to determine the effects of molybdenum and niobium alloys elements on microstructure of this material through hardness measurements, dilatometry, chemical etching, scanning electron microscopy, and mainly, utilizing metallography at high temperatures. The metallography at high temperatures technic allows the study of microstructural changes during the thermal cyc1es, which were scheduled, having as reference the TTT curve previously traced to this material, focusing regions where changes of fase don\'t occur. So the metallographic appearances at high temperatures were obtained and it was done a comparative study using other technics. Because of that is possible to improve the knowledge of the material microstructure, which it has been studied, and to obtain alloys with predetermined properties.
47
Vilela, Rivelino Cunha. « ESTUDO DE TRANSIÃÃES DE FASE EM CRISTAIS DE L-ALANINA + ÃCIDO OXÃLICO ». Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10397.
Texte intégralRésumé :
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorNeste trabalho, estudou-se o efeito da temperatura nos espectros Raman de cristais de L-alanina + Ãcido oxÃlico, C3H8NO2+.C2HO4-. Foram realizadas medidas de espectroscopia Raman em policristais a diferentes temperaturas no intervalo compreendido entre a temperatura ambiente e a temperatura de 20 K, sendo fornecida uma identificaÃÃo tentativa para todos os modos normais de vibraÃÃo observados. Para auxiliar o entendimento do comportamento do cristal tambÃm foram obtidos os difratogramas de raios-X bem como estudada a dependÃncia dos parÃmetros de rede em funÃÃo da temperatura atravÃs de dilatometria no intervalo entre 290 K e 93 K. As trÃs tÃcnicas utilizadas em conjunto permitiram mostrar o comportamento estrutural do material em baixas temperaturas. Deste quadro foi possÃvel inferir que os cristais de L-alanina + Ãcido oxÃlico apresentam trÃs diferentes transiÃÃes de fase durante o resfriamento. Em 250 K o aparecimento de um dubleto em 90 cm-1 e a anomalia num dos parÃmetros de rede apontam para a ocorrÃncia da primeira transiÃÃo de fase. Em 150 K surgem pelo menos duas novas bandas no espectro Raman, ao mesmo tempo em que ocorrem bruscas mudanÃas de inclinaÃÃo nas curvas que representam as dimensÃes dos eixos a e c do cristal. TambÃm se verifica que, de forma semelhante ao que ocorre com os espectros Raman, aparecem novos picos no difratograma de raios-X em torno desta temperatura, caracterizando assim a segunda transiÃÃo de fase. A uma temperatura ainda mais baixa, em torno de 43 K, foi verificada a ocorrÃncia da terceira transiÃÃo de fase, que tem como principal caracterÃstica a separaÃÃo de dois modos Raman associados a modos da rede. MudanÃas nos ambientes dos grupos CH3 e do NH3+ durante o resfriamento sÃo discutidas. Um importante aspecto apresentado pelos espectros Raman com o resfriamento da amostra foi o deslocamento da banda de mais baixa energia para menores valores de frequÃncias, semelhantemente ao que ocorre com vibraÃÃes do tipo soft-mode em materiais ferroelÃtricos, embora a frequÃncia do modo no cristal de L-alanina + Ãcido oxÃlico nÃo tenha ido à zero. Baseado nos resultados acima e nos possÃveis sÃtios de simetria ocupados pelas molÃculas atravÃs do grupo O=CC nas diversas fases, sugere-se a seguinte sequÃncia de transiÃÃes de fase D24 para C2h5 para Cs3 para C23, que aconteceriam, respectivamente, nas temperaturas de 250 K, 150 K e 43 K.
In the present word we have studied the effect of temperature on the Raman spectra of crystals of L-alanine + oxalic acid, C3H8NO2+.C2HO4-. Raman spectroscopy measurements were performed on polycrystalline samples at different temperatures varying in the range from room temperature to T = 20 K; a tentative assignment of all normal modes was furnished. In order to help the understanding of the crystal behavior we have also obtained X-ray diffractograms and studied the dependence of lattice parameters through dilatometry as a function of temperature in the 290 K â 93 K range. The three different techniques allowed us to construct a picture of the material under low temperature conditions. As a consequence we have realized that L-alanine + oxalic acid crystal undergoes three phase transitions at low temperatures. The splitting of a band at 90 cm-1 and an anomaly in one of the lattice parameters are the signature for the first phase transition that is observed at 250 K. At 150 K it was observed the appearance of two new bands in the Raman spectrum and, simultaneously, it was observed change in the curves of a and c lattice parameters. Additionally, it was verified the appearance of new peaks in the X-ray diffractogram at the same temperature, characterizing the second phase transition. At a temperature even lower, at about 43 K, it was verified the occurrence of the third phase transition that has as main characteristic the splitting of two bands that are associated to the lattice modes. Changes in the modes associated with CH3 and NH3+ during the cooling is discussed. An important behavior of the crystal with the cooling process was the red shift of the band of lower frequency, similar to the soft-mode vibration of ferroelectric materials, although the frequency of the mode in L-alanine + oxalic acid does not goes to zero. Based on the results on Raman spectroscopy, dilatometry and X-ray diffraction, and on the possible symmetry sites occupied by the molecules through the O=CC group in the various phases, it is suggested the following sequence of phase transitions D24 C2h5 Cs3 C23, which should occur at 250 K, 150 K and 43 K.
48
Schuldt, Thilo. « An optical readout for the LISA gravitational reference sensor ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16241.
Texte intégralRésumé :
Der weltraumgestützte Gravitationswellendetektor LISA (Laser Interferometer Space Antenna) besteht aus drei identischen Satelliten an Bord derer sich jeweils zwei frei schwebende Testmassen befinden. Die Lage der einzelnen Testmassen in Bezug auf die zugehörige optische Bank muss mit einer Genauigkeit besser 1 pm/sqrt(Hz) in der Abstands- und besser 10 nrad/sqrt(Hz) in der Winkelmessung erfolgen. In der vorliegenden Arbeit wird ein kompaktes optisches Auslesesystem präsentiert, welches als Prototyp für diese Abstands- und Winkelmetrologie dient. Das dafür entwickelte polarisierende Heterodyn-Interferometer mit räumlich getrennten Frequenzen basiert auf einem hoch-symmetrischen Design, bei dem zur optimalen Gleichtakt-Unterdrückung Mess- und Referenzarm die gleiche Polarisation und Frequenz sowie annähernd gleiche optische Pfade haben. Für die Winkelmessung wird die Methode der differentiellen Wellenfrontmessung eingesetzt. In einem ersten Prototyp-Aufbau wird ein Rauschniveau von weniger als 100 pm/sqrt(Hz) in der Translations- und von weniger als 100 nrad/sqrt(Hz) in der Winkelmessung (beides für Frequenzen oberhalb 0.1 Hz) demonstriert. In einem zweiten Prototyp-Aufbau werden zusätzlich eine Intensitätsstabilisierung und ein Phasenlock der beiden Frequenzen implementiert. Die analoge Phasenmessung ist durch eine digitale, FPGA basierte, ersetzt. Mit diesem Aufbau wird ein Rauschen kleiner 5 pm/sqrt(Hz) in der Translationsmessung und kleiner 10 nrad/sqrt(Hz) in der Winkelmessung, beides für Frequenzen größer 0.01 Hz, erreicht. Eine Rausch-Analyse wurde durchgeführt und die Nichtlinearitäten des Interferometers bestimmt. Das Interferometer wurde im Hinblick auf die LISA Mission entwickelt, findet seine Anwendung aber auch bei der Charakterisierung der dimensionalen Stabilität von ultra-stabilen Materialien sowie in der optischen Profilometrie. Die Adaptierung des Interferometers dazu sowie erste Resultate zu beiden Anwendungen werden in dieser Arbeit präsentiert.The space-based gravitational wave detector LISA (Laser Interferometer Space Antenna) consists of three identical satellites. Each satellite accommodates two free-flying proof masses whose distance and tilt with respect to its corresponding optical bench must be measured with at least 1 pm/sqrt(Hz) sensitivity in translation and at least 10 nrad/sqrt(Hz) sensitivity in tilt measurement. In this thesis, a compact optical readout system is presented, which serves as a prototype for the LISA proof mass attitude metrology. We developed a polarizing heterodyne interferometer with spatially separated frequencies. For optimum common mode rejection, it is based on a highly symmetric design, where measurement and reference beam have the same frequency and polarization, and similar optical pathlengths. The method of differential wavefront sensing (DWS) is utilized for the tilt measurement. In a first prototype setup noise levels below 100 pm/sqrt(Hz) in translation and below 100 nrad/sqrt(Hz) in tilt measurement (both for frequencies above 0.1 Hz) are achieved. A second prototype was developed with additional intensity stabilization and phaselock of the two heterodyne frequencies. The analog phase measurement is replaced by a digital one, based on a Field Programmable Gate Array (FPGA). With this setup, noise levels below 5 pm/sqrt(Hz) in translation measurement and below 10 nrad/sqrt(Hz) in tilt measurement, both for frequencies above 0.01Hz, are demonstrated. A noise analysis was carried out and the nonlinearities of the interferometer were measured. The interferometer was developed for the LISA mission, but it also finds its application in characterizing the dimensional stability of ultra-stable materials such as carbon-fiber reinforced plastic (CFRP) and in optical profilometry. The adaptation of the interferometer and first results in both applications are presented in this work.
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Santos, Igor Miguel da Cunha. « Elaboração de um diagrama TAC para um aço de alta tenacidade API X-70 ». Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11187.
Texte intégralRésumé :
Dissertação para obtenção do Grau de Mestre em Engenharia de MateriaisOs diagramas TTT-TAC são muito utilizados em soldadura, porque através destes diagramas é possível estimar a presença de uma dada fase e determinar a microestrutura de uma liga soldada, antecipando possíveis problemas de soldabi-lidade e fases indesejáveis, permitindo seleccionar os parâmetros de soldadura de modo a contolar a velocidade de arrefecimento. O aço em estudo (HSLA API X-70 microligado com nióbio) é essencialmente utilizado para as indústrias de petróleo e gás natural (oleodutos e gasodutos). É um aço de baixa liga, baixo teor em Carbono (para aumentar a sua soldabilidade), com adição de pequenas quantidades de alguns elementos de liga como o manga-nês, o nióbio e o molibdénio (para lhe conferir resistência mecânica). É caracteri-zado por uma boa soldabilidade, alta resistência mecânica, resistência à corrosão e alta tenacidade. Este trabalho teve como objectivo a elaboração do diagrama TAC a partir dos dados dilatométricos efectuados na Universidade Tecnológica de Graz na Áustria. Os provetes ensaiados foram estudados para identificação de estruturas com dife-rentes contrastantes para identificar as fases presentes e microdureza Vickers. A construção do diagrama TAC experimental resultou do relacionamento da informação recolhida durante este trabalho experimental: análise das curvas dila-tométricas, identificação das fases presentes das micrografias, microdurezas e das temperaturas de transformação teóricas calculadas.
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Mateus, Cárin Cristina de Almeida. « Determinação dos erros de medição associados ao ensaio DMT ». Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/2716.
Texte intégralRésumé :
Mestrado em Engenharia GeológicaA evolução tecnológica verificada sobretudo nos últimos 20 anos revolucionou de forma drástica o contexto da prática da engenharia, nomeadamente pelo desenvolvimento de modelos numéricos de elevada precisão e fiabilidade, que facilitam a simulação de comportamentos e de soluções de engenharia. A eficiência e a qualidade dos resultados desses modelos estão intrinsecamente relacionadas com a selecção dos parâmetros de entrada, os quais dependem sobretudo da qualidade dos equipamentos de medição, da sua adequabilidade a cada situação particular e dos erros associados a cada um dos parâmetros medidos. No presente trabalho, apresenta-se uma análise de sensibilidade paramétrica a fim de verificar a precisão associada e as respectivas implicações na parametrização física e mecânica dos maciços terrosos caracterizados com base no ensaio com Dilatómetro de Marchetti, DMT. ABSTRACT: In the last two decades, the practice of engineering has immensely benefitted from technological evolution. Namely, the development of models and numerical methods with very high precision and efficiency, made it possible to simulate quite accurately the behaviour of engineering problems. Nevertheless, the efficiency and quality of the results obtained from such models, strongly depend on the selection of the input parameters and also on the quality of the equipment used to measure them. In particular, the adequacy of the equipment to a particular situation and the inherent errors associated to any measurement, have an important role in this process. In this work we present an analysis of parametric sensitivity to the Marchetti Dilatometer Test, DMT, with the aim of checking its precision and the respective implications on the physical and mechanical parametrization of soils.