Na indústria hidrometalúrgica, diversos materiais são utilizados para a construção dos equipamentos, a fim de satisfazer as necessidades dos processos que estão sujeitos, tendo em conta a importância deles em condições complexas, tais como erosão e a corrosão. Neste trabalho é avaliado o comportamento de um aço inoxidável martensítico AISI 410 tratado termicamente com têmpera e revenimento, frente aos revestimentos Carbeto de Tungstênio (86WC-10Co4Cr) obtido por aspersão térmica (High Velocity Oxygen Fuel-HVOF), e um elastômero PUR comercial MetaLine 785 em condições de desgaste do tipo lama, analisando a perda de volume, a determinação da área e profundidade erodida das amostras, para os ângulos de incidência de 30∘ e 90∘ entre o eixo de simetria do fluxo do fluido e a superfície das amostras. Os ensaios foram realizados para os diferentes tipos de materiais em um equipamento para ensaios simulados de lama, desenvolvido como parte da pesquisa no LACER (Laboratório de Materiais Cerâmicos) da Universidade Federal do Rio Grande do Sul (UFRGS), sob controle de parâmetros como ângulo de impacto e sua velocidade, temperatura de ensaio e concentração de partículas erosivas na suspensão, neste caso foi usada alumina eletrofundida ALO marrom da companhia Treibacher. Realizou-se a caracterização dos materiais, na sua microestrutura Microscopia Eletrônica de Varredura (MEV), Microscopia Óptica (M.O), espessura, rugosidade, porosidade, microdureza e estruturalmente na identificação de fases Difração de Raios X (DRX), Espectroscopia por Energia Dispersiva (EDS), o analise térmico Perda ao Fogo (LOI) para o caso do elastômero PUR, e a distribuição de tamanho de partícula (LG) e morfologia para o erodente. Com a pesquisa conseguiu-se estabelecer as relações entre o desgaste erosivo por lama e as propriedades físicas relacionadas aos materiais avaliados, nas condições estabelecidas no ensaio de erosão do equipamento, e concluiu-se que o revestimento de 86WC-10Co4Cr carbeto de Tungstênio apresentou uma melhor resistência ao desgaste erosivo tipo lama, em comparação com o aço inoxidável martensítico AISI 410 e o elastômero PUR comercial MetaLine 785. / In the hydrometallurgical industry, many materials are used in the construction of the equipment in order to satisfy the needs of the processes to which they are subjected, taking into account their importance in complex conditions such as erosion and corrosion. In this work, the behavior of a quenched and tempered AISI 410 martensitic stainless steel is compared to tungsten carbide (86WC-10Co4Cr) obtained by thermal spray (High Velocity Oxygen Fuel - HVOF) and to a commercial elastomer PUR MetaLine 785 under slurry erosion conditions. Volume loss, area determination and eroded depth of the samples were analyzed at angles of incidence of 30∘ and 90∘ between the axis of symmetry of the fluid flow and the surface of the samples. The tests were carried out for the different types of materials in a slurry erosion simulation device, developed as part of the research in LACER (Laboratory of Ceramic Materials) of the Federal University of Rio Grande do Sul (UFRGS), via the control of parameters such as angle and speed of impact, test temperature and concentration of erosive particles in the suspension. In this case, electrofused brown ALO alumina (Treibacher) was used. The materials were characterized with regard to their microstructure (SEM), thickness, roughness, porosity, microhardness, structure in the phase identification (DRX) (EDS), thermal analysis (LOI) in the case of the PUR elastomer and the particle size distribution (LG) and morphology for the erodent. The research was able to establish the relationships between the slurry erosive wear and the physical properties related to the evaluated materials, under the conditions established in the erosion test of the equipment. It was concluded that the coating 86WC-10Co4Cr tungsten carbide presented better resistance to the slurry erosion wear when compared to AISI 410 martensitic stainless steel and the PUR commercial elastomer MetaLine 785.

A agricultura demanda grande quantidade de água para a produção de alimentos e fibras. Técnicas que determinem e monitorem a dinâmica da água no solo são importantes para promover o uso correto e consciente desse recurso natural. Diante do exposto, a tensiometria é uma ferramenta eficiente na determinação da dinâmica da água em solos agrícolas, podendo ser utilizada em conjunto com sensores de capacitância para a caracterização da curva de retenção de água no solo. Contudo, apesar de práticos, erros associados à instalação e às características das cápsulas podem comprometer a precisão dos tensiômetros. Esse trabalho teve como objetivo testar a influência do uso de lama de solo no momento da instalação, bem como o formato e condutância hidráulica de cápsulas de tensiômetros de punção sobre o potencial matricial da água no solo, tendo-se como referência tensiômetros com manômetro de mercúrio. Também, se objetivou determinar a curva de retenção de água no solo com base nos dados obtidos por tensiometria e de um sensor de capacitância. Os resultados mostram que o formato das cápsulas de cerâmica e a lama de solo influenciaram as determinações do potencial matricial, ao contrário da condutância hidráulica das cápsulas. A lama de solo é indicada na instalação de tensiômetros com manômetro de mercúrio e de punção. As curvas de retenção diferiram quanto aos sistemas de aquisição (manômetro de mercúrio ou tensímetro); no entanto, o modelo ajustado não foi sensível em distinguir diferenças entre os tratamentos quanto ao formato das cápsulas ou uso de lama de solo. De modo geral, ocorreu uma subestimativa dos ajustes das curvas de retenção para os tensiômetros de punção, o que pode levar a interpretações errôneas das curvas de retenção de água no solo quando determinadas por meio desses instrumentos. / The agriculture demand large amounts of water for food and fiber production. The techniques used to determine and monitor the water dynamics in the soil are important to promote the correct and conscious use of this natural resource. Given the above, the tensiometry is an efficient tool for the determination the water dynamics in soils, which can be used in conjunction with capacitance sensors to characterize the water retention curve in the soil. However, although practical, errors associated with the installation and the characteristics of the capsules may compromise the accuracy of tensiometers. This study aimed to test the influence of the use of soil slurry during the tensiometer installation, the format and hydraulic conductance of the capsules from puncture tensiometers on the matric potential of soil water, taking as reference tensiometers equipped with mercury manometers. In addition, aimed to determine the soil-water retention curve based on data obtained by tensiometry and a capacitance sensor. The results shows that the format of the ceramic capsules and the use of the slurry influenced the measurements of matric potential, as opposed to hydraulic conductance of the capsules. The soil slurry is recommended for tensiometers equiped with mercury manometer and puncture tensiometers. The retention curves differed among the acquisition systems (mercury manometer or tensimeter); however, the fitted model was not sensitive enough to distinguish differences between treatments for the format of the capsules or the use of soil slurry. In general, there was an underestimation of the retention curve for puncture tensiometers, which can lead to erroneous interpretations of the soil-water retention curve when determined by these instruments.

O transporte de minério em tubos é feito em larga escala não somente em longas distâncias, (através de minerodutos); como também dentro da mina, seja no trajeto entre a mina e a usina, como no caso de minerais lavrados por desmonte hidráulico, ou entre as operações unitárias dentro da usina de beneficiamento. O projeto dos sistemas de bombeamento de polpas requer o conhecimento das variáveis de escoamento, a perda de carga (ΔP) e a velocidade de deposição (Vd). Discutem-se aqui alguns modelos de predição para tais variáveis. Apesar da irrefutável importância deste tipo de transporte, ainda não há consenso sobre a validade dos modelos existentes. Este trabalho teve como objetivo a análise comparativa dos modelos de velocidade de deposição propostos por Durand e Condolios (1952), Wasp et al. (1977) e Wilson et al. (2006), e os modelos de perda de carga propostos por Durand e Condolios (1952), Wasp et al. (1977) e Newitt et al. (1955) com os resultados de laboratório. A acurácia dos modelos, apesar das limitações de cada um, é crucial para que as variáveis de projeto do sistema de bombeamento sejam estabelecidas por meio do uso desses modelos. A comparação foi baseada em ensaios realizados em três test loops de diâmetros de 2\", 3\" e 4\" com minério de ferro, carbonatito e areia, em concentrações de sólidos de 15%, 30% e 50%. Trabalhando com minérios de diferentes granulometrias, densidades e polpas com concentrações diferentes pudemos analisar a interferência desses parâmetros no escoamento e no uso dos modelos propostos. Os modelos de Vd se mostraram bastante úteis, sendo que o modelo proposto por Durand e Condolios (1952) teve as melhores correlações para todos os materiais estudados. Já os modelos de perda de carga não mostraram correlações aceitáveis com os resultados de laboratório, endossando as indicações de alguns autores, como Chaves (2012) e Abulnaga (2002) que não recomendam o uso de modelos de predição de perda de carga nos cálculos de dimensionamento destes sistemas. Como alternativa, é possível utilizar plantas piloto e ensaios laboratoriais. / Ore transportation in pipes is carried out on a large scale not only at long distances, such as ore pipelines, but also within the mine, or in the path between the mine and the plant, as the case of minerals drawn by hydraulic dismantling, or between operations within the beneficiation plant. The design of the slurry pumping systems requires the knowledge of the flow variables, as the head loss (ΔP) and the deposition velocity (Vd). Some prediction models for such variables are discussed in this dissertation. Despite the irrefutable importance of this type of transportation, there is still no agreement on the validity of the existing models. Their limitations make unfeasible to use them, and much more is necessary to improve in this field. This work aimed to make a comparative analysis of the deposition velocity models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Wilson et al. (2006), and the head loss models proposed by Durand and Condolios (1952), Wasp et al. (1977) and Newitt et al. (1955) with laboratory results. The accuracy of the models, despite the limitations of each one, is crucial if pumping system design variables are established using these models. The comparison was based on laboratory tests performed on three diameter test loops, 2 \", 3\" and 4 \" with iron ore, carbonatite and sand a concentrations of 15%, 30% and 50% in weight solids concentrations. Working with different ore grain sizes and densities ores and pulps with different concentrations we can analyze the interference of these parameters in the flow and in the models use. The Vd models were very useful, and the Durand and Condolios (1952) model showed the best correlations for all ores studied. However, the head loss models did not show acceptable correlations with the laboratory results, endorsing the indications of some authors, such as Chaves (2012) and Abulnaga (2002), who do not recommend the use of prediction models for head loss in these systems sizing. Alternatively, it is possible to use pilot plants and laboratory tests.

Made available in DSpace on 2017-07-10T19:25:14Z (GMT). No. of bitstreams: 1 fabio.pdf: 669831 bytes, checksum: 4234cdb41111aee1569cd3f350a5f7ca (MD5) Previous issue date: 2012-03-01 / The application rates of swine wastewater used in crop production should be enough to meet the demand for plant nutrients. Thus, it is justified the need to research its use and management as a fertilizer for applications to be made according to technical recommendations. Taking into account its features, soil characteristics and crop were taken into account. In this context, the aim of this study was to monitor wastewater influence as topdressing to maize (Zea mays L.) and black oats (Avena strigosa Schreb.) crops in sequence. Five rates of wastewater application (0; 100; 200; 300 e 537 m3ha-1 equivalents to 0; 11,2; 22,3; 33,5 and 60 kg ha-1 of N respectively, based on an average concentration of N on swine wastewater) were tested in four replications each. In maize and black oats were performed foliar and plant tissue analysis. In the soil porosity, bulk density, soil water content, pH, carbon, CEC (Cation Exchangeable Capacity), alkaline saturation, potential acidity and nutrients were determined at the final maize and black oats cycles. The topdressing on maize crop sowing crop increased foliar content of P, N e Mn, decreased the foliar content of K and Mg. In black oats crop the residual effects provided 87% dry mass increase, chlorophyll content, foliar contents of N, Ca and Na, and decreased the relation between leaf/stem and contents of P, K, Mg and Cu. The crops under swine wastewater treatment did not show nutrients deficiency. There was a decrease on the macropores and total soil porosity when the application rate of swine wastewater increased on maize crop. The roots development of black oats contributed to improve the soil physical quality and decreased the compaction on 0 to 15 cm, upper layer. There were an increases of K+, Cu and Zn contents, potential acidity and cation exchange capacity and decreases of Ca2+, Mg2+ and Fe contents, base saturation and soil pH. In this experiment, rates up to 200 m3ha-1 (except control) showed available results of nutrients; which did not cause deficiency on soil aeration, important to crops. Thus, it can be used as maize topdressing. / As taxas de aplicação de águas residuárias de suinocultura (ARS) utilizadas na produção agrícola devem ser suficientes para suprir a demanda das plantas por nutrientes. Justifica-se, então, a necessidade de pesquisas sobre uso e manejo da água residuária de suinocultura como fertilizante, para que aplicações sejam feitas de acordo com recomendações técnicas, levando-se em conta sua composição, as características do solo e da cultura. Neste contexto, o objetivo deste trabalho foi monitorar a influência do uso da água residuária de suinocultura, aplicada como adubação de cobertura na cultura do milho com cultivo sequencial de aveia preta. Cinco taxas de aplicação de água residuária (0; 100; 200; 300 e 537 m3ha-1, equivalentes a 0; 11,2; 22,3; 33,5 e 60 kg ha-1 de N respectivamente, baseado na concentração média de N na ARS) foram testadas, com quatro repetições cada. No milho e na aveia preta foram feitas análises foliares e do tecido vegetal. No solo foram determinados: porosidade do solo, densidade, teor de água, pH, carbono, CTC, saturação por bases, acidez potencial e nutrientes, antes da semeadura do milho e ao final dos ciclos do milho e aveia preta. A adubação de cobertura na cultura do milho elevou os teores foliares de P, N e Mn e diminuiu os teores foliares de K e Mg. Na cultura da aveia preta, o efeito residual proporcionou aumento de 87% na massa seca, teor de clorofila, teores foliares de N, Ca e Na, e diminuiu a relação folha/colmo e teores de P, K, Mg, Cu. As culturas sob tratamentos com ARS não apresentaram deficiência de nutrientes. Houve redução da macroporosidade e porosidade total do solo, quanto maior foi a taxa de aplicação de ARS na cultura do milho. A introdução da aveia preta contribuiu para melhorar a qualidade física do solo e reduziu a compactação na camada superficial de 0-15 cm. Houve aumento dos teores de K+, Cu e Zn, acidez potencial e capacidade de troca de cátions e reduziu teores de Ca2+, Mg2+ e Fe, saturação por bases e pH do solo. Neste experimento, taxas com até 200 m3ha-1 (exceto testemunha) apresentaram resultados de suficiência de nutrientes e não provocaram deficiência na aeração do solo, o que foi benéfico para as culturas, podendo ser utilizadas como adubação de cobertura em milho.

Made available in DSpace on 2017-05-12T14:48:39Z (GMT). No. of bitstreams: 1 fabio.pdf: 669831 bytes, checksum: 4234cdb41111aee1569cd3f350a5f7ca (MD5) Previous issue date: 2012-03-01 / The application rates of swine wastewater used in crop production should be enough to meet the demand for plant nutrients. Thus, it is justified the need to research its use and management as a fertilizer for applications to be made according to technical recommendations. Taking into account its features, soil characteristics and crop were taken into account. In this context, the aim of this study was to monitor wastewater influence as topdressing to maize (Zea mays L.) and black oats (Avena strigosa Schreb.) crops in sequence. Five rates of wastewater application (0; 100; 200; 300 e 537 m3ha-1 equivalents to 0; 11,2; 22,3; 33,5 and 60 kg ha-1 of N respectively, based on an average concentration of N on swine wastewater) were tested in four replications each. In maize and black oats were performed foliar and plant tissue analysis. In the soil porosity, bulk density, soil water content, pH, carbon, CEC (Cation Exchangeable Capacity), alkaline saturation, potential acidity and nutrients were determined at the final maize and black oats cycles. The topdressing on maize crop sowing crop increased foliar content of P, N e Mn, decreased the foliar content of K and Mg. In black oats crop the residual effects provided 87% dry mass increase, chlorophyll content, foliar contents of N, Ca and Na, and decreased the relation between leaf/stem and contents of P, K, Mg and Cu. The crops under swine wastewater treatment did not show nutrients deficiency. There was a decrease on the macropores and total soil porosity when the application rate of swine wastewater increased on maize crop. The roots development of black oats contributed to improve the soil physical quality and decreased the compaction on 0 to 15 cm, upper layer. There were an increases of K+, Cu and Zn contents, potential acidity and cation exchange capacity and decreases of Ca2+, Mg2+ and Fe contents, base saturation and soil pH. In this experiment, rates up to 200 m3ha-1 (except control) showed available results of nutrients; which did not cause deficiency on soil aeration, important to crops. Thus, it can be used as maize topdressing. / As taxas de aplicação de águas residuárias de suinocultura (ARS) utilizadas na produção agrícola devem ser suficientes para suprir a demanda das plantas por nutrientes. Justifica-se, então, a necessidade de pesquisas sobre uso e manejo da água residuária de suinocultura como fertilizante, para que aplicações sejam feitas de acordo com recomendações técnicas, levando-se em conta sua composição, as características do solo e da cultura. Neste contexto, o objetivo deste trabalho foi monitorar a influência do uso da água residuária de suinocultura, aplicada como adubação de cobertura na cultura do milho com cultivo sequencial de aveia preta. Cinco taxas de aplicação de água residuária (0; 100; 200; 300 e 537 m3ha-1, equivalentes a 0; 11,2; 22,3; 33,5 e 60 kg ha-1 de N respectivamente, baseado na concentração média de N na ARS) foram testadas, com quatro repetições cada. No milho e na aveia preta foram feitas análises foliares e do tecido vegetal. No solo foram determinados: porosidade do solo, densidade, teor de água, pH, carbono, CTC, saturação por bases, acidez potencial e nutrientes, antes da semeadura do milho e ao final dos ciclos do milho e aveia preta. A adubação de cobertura na cultura do milho elevou os teores foliares de P, N e Mn e diminuiu os teores foliares de K e Mg. Na cultura da aveia preta, o efeito residual proporcionou aumento de 87% na massa seca, teor de clorofila, teores foliares de N, Ca e Na, e diminuiu a relação folha/colmo e teores de P, K, Mg, Cu. As culturas sob tratamentos com ARS não apresentaram deficiência de nutrientes. Houve redução da macroporosidade e porosidade total do solo, quanto maior foi a taxa de aplicação de ARS na cultura do milho. A introdução da aveia preta contribuiu para melhorar a qualidade física do solo e reduziu a compactação na camada superficial de 0-15 cm. Houve aumento dos teores de K+, Cu e Zn, acidez potencial e capacidade de troca de cátions e reduziu teores de Ca2+, Mg2+ e Fe, saturação por bases e pH do solo. Neste experimento, taxas com até 200 m3ha-1 (exceto testemunha) apresentaram resultados de suficiência de nutrientes e não provocaram deficiência na aeração do solo, o que foi benéfico para as culturas, podendo ser utilizadas como adubação de cobertura em milho.

Avaliação da aderência de chapiscos em substratos de concretos estruturais. Com o objetivo de aprimorar a microestrutura da zona de interface argamassa/concreto e aumentar a resistência de aderência do revestimento, utilizou-se chapisco com baixa relação água/aglomerante e adição da sílica ativa extraída da casca de arroz como tratamento da zona de interface da argamassa e substrato. Para avaliar a aderência do revestimento realizaram-se ensaios de determinação da resistência de aderência à tração. Utilizou-se a técnica de microscopia eletrônica de varredura associada à espectrografia por dispersão de energia para analisar a microestrutura da zona de interface do chapisco e concreto. Os resultados do programa experimental evidenciaram que, quando se utiliza a sílica extraída da casca de arroz no chapisco, em teores de 5% em relação à massa de cimento, há aumentos significativos de resistência de aderência do revestimento. Nos estudos microestruturais, foi possível observar que devido às ações físicas e químicas da sílica da casca de arroz, formou-se uma microestrutura densa, de baixa porosidade e com a presença de produtos hidratados pouco cristalinos na interface chapisco/concreto. A implementação de uma ponte de ligação constituída por chapiscos com sílica ativa, entre os substratos e as argamassas de revestimento, mostrou-se eficiente em superfícies muito lisas ou em materiais pouco porosos, como no caso das estruturas de concreto armado. / The present thesis evaluates the adherence of slurry mortars in substrates of structural concretes. To optimize the microstructure of the interfacial transition zone of mortar and concrete and to improve the adherence of mortar renderings, slurry mortars of lower water/cement ratio with silica obtained from rice husk were used as treatment of interfacial transition zone. In order to evaluate adherence, bond strength tests were realized. The microstructural characterization of the interfacial transition zone of slurry mortars and concrete was performed by scanning electronic microscopy. The results indicate that adding silica obtained from rice husk into the slurry mortars increases the bond strength. Moreover, the formation of a dense microstructure is observed in the interfacial transition zone of slurry mortar and concrete due to the microfiller effect and high pozzolanic activity of the silica obtained from rice husk. The implementation of a connection bridge constituted by slurry mortars with the addition of the silica obtained from rice husk between the substrate and the mortar rendering showed to be efficient in the substrates with low porosity, as in the case of concrete structures.

Abstract This thesis has been made within the European Industrial Doctorate (EID) project called Mathematics and Materials Science for Steel Production and Manufacturing, abbreviated as MIMESIS, which has five partners: EFD Induction in Norway; SSAB, Outokumpu, and the University of Oulu in Finland; and Weierstrass Institute for Applied Analysis and Stochastics (WIAS) in Germany. The main aim of this work was to develop a steel composition and processing route suitable for making a slurry transportation pipeline with the aid of induction hardening, and to characterize the phase transformations and microstructures involved in the various stages of the processing route. A novel steel chemistry was designed based on metallurgical principles assisted by computational thermodynamics and kinetics. The designed composition is a medium-carbon, low-alloy steel microalloyed with niobium, in wt.% 0.40 C, 0.20 Si, 0.25 Mn, 0.50 Mo, 0.90 Cr, and 0.012 Nb. This was subsequently cast, thermomechanically rolled on a laboratory rolling mill to two bainitic microstructures, and finally subjected to the thermal cycles predicted to be encountered with the internal induction hardening of a typical pipe geometry. The phase transformations and microstructures found at various stages of the simulated production process have been characterized and algorithms developed to enable the optimization of microstructure and hardness through the pipe wall thickness. / Tiivistelmä Tämä väitöskirja on tehty osana Euroopan teollisuustohtori (European Industrial Doctorate, EID) -ohjelmaa projektissa eli Matematiikka ja materiaalitiede teräksen valmistuksessa ja käytössä (Mathematics and Materials Science for Steel Production and Manufacturing, MIMESIS). Ohjelmassa on viisi partneria: EFD Induction Norjasta; SSAB, Outokumpu ja Oulun yliopisto Suomesta; ja Weierstrass Institute for Applied Analysis and Stochastics (WIAS) Saksasta. Työn päätavoitteina oli kehittää teräksen koostumusta ja prosessointireittiä, jotka soveltuvat lietteen kuljetusputken valmistukseen induktiokarkaisun avulla, sekä karakterisoida prosessin eri vaiheiden aikana tapahtuvat faasimuutokset ja mikrorakenteet. Uusi teräskoostumus suunniteltiin metallurgisten periaatteiden pohjalta hyödyntämällä laskennallista termodynamiikkaa ja kinetiikkaa. Suunniteltu teräs on niobilla mikroseostettu, matalaseosteinen ja keskihiilinen, eli painoprosentteina 0,40 C, 0,20 Si, 0,25 Mn, 0,50 Mo, 0,90 Cr ja 0,012 Nb. Teräs valettiin, valssattiin ja jäähdytettiin termomekaanisesti laboratoriovalssaimella kahdeksi bainiittiseksi mikrorakenteeksi ja lopulta altistettiin lämpösykleille, joiden ennustettiin olevan tyypillisiä sisäisesti induktiokarkaistulle teräsputkelle. Simuloidun tuotantoprosessin eri vaiheissa havaitut faasimuutokset ja mikrorakenteet on karakterisoitu. Sen lisäksi on kehitetty algoritmit, jotka mahdollistavat mikrorakenteen ja kovuuden optimoinnin putken seinämän paksuuden läpi.

Global planarization is one of the major demands of the semiconductor industry. Chemical mechanical polishing (CMP) is the planarization method of choice use to achieve the required stringent tolerances essential for successful fabrication of next generation Integrated Circuits (IC). The predominant reason for CMP defects is the shear and normal stresses during polishing to which the material is subjected. Understanding the process of CMP and factor that contribute to overall stress addition during polishing requires an approach that encompasses all the four major categories of variables, namely: a) machine parameters, b) material properties, c) polishing pad characteristics, and d) polishing slurry performance. In this research, we studied the utilized in-situ technique involving acoustic emission (AE) signal monitoring and coefficient of friction (COF) monitoring using a CETRTM Bench Top CMP Tester to evaluate the impact of variation in machine parameters on the CMP process. The mechanical and tribological properties of different candidate materials have been evaluated bring potential challenges in their integration to the fore. The study also involves destructive and non destructive testing of polishing pads performed for characterization and optimization of polishing pad architecture. Finally, the investigation concludes proposing novel nanoparticle CMP slurry which has a predominant chemical component in its polishing mechanism. It was found that the decrease in the mechanical shear and normal loading by: a) operating the process in the low stress regime, b) using potential materials that are mechanically stronger, c) using polishing pads with lesser variation in specific gravity and with a surface that is has its mechanical properties fine tuned to those of the wafer, and d) deploying polishing slurry with a significant chemical component mechanical removal, are some of the approaches that can be employed to meet the future challenges of the CMP process and reduce the defect associated with it.

In this dissertation, an experimental and numerical study of dense coarse solids-liquid flows has been performed. The experimental work mainly involved pressure drop measurements in a vertical flow loop. A limited number of measurements of solids velocity profiles were also obtained in the upward flow section of the flow loop. The numerical work involved simulations of coarse particles-in-water flows in vertical and horizontal pipes. The vertical flow simulations were performed using the commercial CFD software, ANSYS CFX-4.4, while ANSYS CFX-10 was used to simulate the flows in the horizontal pipes. The simulations were performed to investigate the applicability of current physically-based models to very dense coarse-particle flows.<p> In the experimental study, measurements of pressure drop and local solids velocity profiles were obtained. The experiments were conducted in a 53 mm diameter vertical flow loop using glass beads of 0.5 mm and 2.0 mm diameter solids for concentration up to 45%. The liquid phase was water. The measured pressure drop exhibited the expected dependence on bulk velocity and solids mean concentration. The wall shear stress was determined by subtracting the gravitational contribution from the measured pressure drop. For flow with the 0.5 mm particles at high bulk velocities, the values of the wall shear stress were essentially similar for each concentration in the upward flow sections but more variation, indicating the effect of concentration, was noted in the downward flow section. At lower bulk velocities, the wall shear stresses with the 0.5 mm glass beads-water flow showed a dependence on concentration in both test sections. This was attributed to an increase in the slip velocity. For the large particle (2.0 mm glass beads), similar observations were made but the effect of concentration was much less in the upward test section. In the downward test section, the wall shear stress for the flow of the 2.0 mm glass beads increased by almost a constant value for the bulk velocities investigated. The solids velocity profiles showed that the solids velocity gradient is large close to the wall. In addition, the solids velocity profiles indicated that the slip velocity increased at lower velocities due to increase in the bulk concentration in the upward flow section.<p> For the vertical flow simulations, different physical models based on the kinetic theory of granular flows were programmed and implemented in ANSYS CFX-4.4. These models, referred to as the kf-ef-ks-es, kf-ef-ks-es-Ts and kf-ef-ks-kfs models, were investigated by focusing on the closure laws for the solids-phase stress. The treatment of the granular temperature Ts depends on whether small- or large-scale fluctuating motion of the particles is considered. The models were implemented via user-Fortran routines. The predicted results were compared with available experimental results. The predicted solids-phase velocity profiles matched the measured data quite well close to the pipe wall but over-predicted it in the core region. The solids concentration, on the other hand, was significantly under-predicted for concentrations higher than 10%. Variations in the predictions of the phasic turbulent kinetic energy and the eddy viscosity were noted; the effect of solids concentration on them was mixed. A general conclusion drawn from the work is that a more accurate model is required for accurate and consistent prediction of coarse particle flows at high concentrations (less than 10%). In a related study, attention was given to wall boundary conditions again focusing on the effect of the solids-phase models at the wall. Comparison between numerical predictions, using some of the existing wall boundary condition models for the solids phase in particulate flows, with experimental results indicated that the physical understanding of the influence of the fluid and solids-phase on each other and their effect on frictional head loss is far from complete. The models investigated failed to reproduce the experimental results. At high solids concentration, it was apparent from the present study that the no-slip and free-slip wall boundary conditions are not appropriate for liquid-solid flows.<p> For the horizontal flow case, three-dimensional simulations were performed with a focus on the velocity and concentration distributions. Medium and coarse sand-in-water flows in three pipe diameters were considered to investigate the default solids stress models in ANSYS CFX-10. Simulations were performed for three cases by considering: 1) no additional solids-phase stress, i.e. no model for Ts; 2) a zero equation, and 3) an algebraic equilibrium model for the granular temperature. The model predictions were compared to experimental results. The effect of particle size, solids-phase concentration, and pipe diameter was explored using the algebraic equilibrium model. All the cases for the models considered exhibited the characteristic features of horizontal coarse particle slurry flows. The zero equation and the algebraic equilibrium model for the granular temperature produced similar results that were not significantly different from the prediction obtained when no solids-phase stress was considered. The comparison with experimental results was mixed. Locally, the measured solids-phase velocity distributions were over-predicted, whereas the solids concentration was reasonably reproduced in the core of all the pipes. The concentration at the bottom and top walls were over-, and under-predicted, respectively. This was attributed to the inappropriate phasic wall boundary condition models available.

Because of their good mechanical resistance at high temperature, Ni-based superalloys are used for aero-engine and land-based turbines but undergo "dry" oxidation between 900 and 1500°C. These materials are thus coated with nickel-aluminide coatings (BC). An additional thermal barrier coating (TBC) is generally applied in the hottest sections of the turbines (T>1050°C) to lower the impact of the temperature on the substrate. In the framework of the European research programme "PARTICOAT", this PhD work was focused on the growth mechanisms of a full protective coating system (BC+TBC) in a single step process, using a water-based slurry containing a dispersion of Al micro-particles to satisfy the European environmental directives. The rheological and physico-chemical characterizations showed the slurry stability up to seven days. After depositing the latter by air spraying, a tailored thermal treatment resulted in a nickel-aluminide coating (β-NiAl) similar to the conventional industrial ones but through an intermediate Al liquid phase stage. Simultaneously, the oxidation of the Al micro-particles brought aboutthe formation of a top alumina "foam" (PARTICOAT concept). After a validation step of the mechanisms involved in pure Ni substrate, the extrapolation of the process to several Ni-based superalloys (René N5 (SX), CM-247 (DS), PWA- 1483 (SX) and IN-738LC (EQ)) revealed different coating compositions and microstructures. A particular attention was therefore paid onto the effect of alloying elements (Cr, Ta, Ti) as well as their segregation in the coating. The high temperature behaviour of the coated samples has been studied through isothermal oxidation (1000h in air between 900 and 1100°C) and showed that the oxidation and interdiffusion phenomena ruled the degradation mechanisms. Besides, the electrodeposition of ceria before the application of the PARTICOAT coating allowed to strongly limit interdiffusion phenomena and stabilized the nickel aluminide coating.