Em metalurgia, a busca pela qualidade, baixo custo e alta produtividade têm feito empresas e institutos de pesquisa trabalharem juntos, procurando novas tecnologias que supram as necessidades do mercado. Dentre essas novas tecnologias, se destaca o processo de lingotamento contínuo de tiras de aço, utilizando o conceito de twin roll, cuja proposição inicial foi sugerida no século XIX por Henry Bessemer. Este trabalho apresenta a modelagem, análise e controle de um sistema de bobinamento de tiras de aço produzidas através de lingotamento contínuo do tipo twin roll , em uma planta localizada no Instituto de Pesquisas Tecnológicas de São Paulo. As características do processo foram primeiramente apresentadas. A modelagem matemática do sistema de bobinamento foi realizada, levando-se em consideração os componentes envolvidos no sistema. As variações paramétricas foram então evidenciadas. O sistema de controle foi primeiramente implementado utilizando-se um controlador do tipo PID, pelo fato desse tipo de controle ser altamente difundido industrialmente. Para maior precisão do sistema de controle, propôs-se a introdução de um sensor ultrasônico para medição das variações do raio de bobinamento. Por último realizou-se o projeto de um compensador robusto utilizando a metodologia LQG/LTR. Para a realização das simulações utilizou-se o programa Matlab/simulink. / In metallurgy, the quest for quality, low cost, and high productivity have resulted in companies and research institutes working together to find new technologies to satisfy the customer demand. Among these new technologies is the direct steel strip casting, using the twin roll concept suggested in the 19th century by Henry Bessemer. This work presents the modelling, analysis and control of a steel strip coiling system using twin roll direct casting, in a plant installed at the Technological Research Institute of Sao Paulo. The characteristics of the process are first introduced. The mathematic modelling of the coiling system used, take into account the system components. The parametric changes were adressed. The control system was first implemented using a PID controller as this kind of control is highly used in the industry. An ultrasonic sensor was introduced in the system to improve the control precision by coiling radius measurement. Last a robust compensator using the LQG/LTR method was designed. The simulations were done using Matlab/Simulink software.

Em metalurgia, a busca pela qualidade, baixo custo e alta produtividade têm feito empresas e institutos de pesquisa trabalharem juntos, procurando novas tecnologias que supram as necessidades do mercado. Dentre essas novas tecnologias, se destaca o processo de lingotamento contínuo de tiras de aço, utilizando o conceito de twin roll, cuja proposição inicial foi sugerida no século XIX por Henry Bessemer. Este trabalho apresenta a modelagem, análise e controle de um sistema de bobinamento de tiras de aço produzidas através de lingotamento contínuo do tipo twin roll , em uma planta localizada no Instituto de Pesquisas Tecnológicas de São Paulo. As características do processo foram primeiramente apresentadas. A modelagem matemática do sistema de bobinamento foi realizada, levando-se em consideração os componentes envolvidos no sistema. As variações paramétricas foram então evidenciadas. O sistema de controle foi primeiramente implementado utilizando-se um controlador do tipo PID, pelo fato desse tipo de controle ser altamente difundido industrialmente. Para maior precisão do sistema de controle, propôs-se a introdução de um sensor ultrasônico para medição das variações do raio de bobinamento. Por último realizou-se o projeto de um compensador robusto utilizando a metodologia LQG/LTR. Para a realização das simulações utilizou-se o programa Matlab/simulink. / In metallurgy, the quest for quality, low cost, and high productivity have resulted in companies and research institutes working together to find new technologies to satisfy the customer demand. Among these new technologies is the direct steel strip casting, using the twin roll concept suggested in the 19th century by Henry Bessemer. This work presents the modelling, analysis and control of a steel strip coiling system using twin roll direct casting, in a plant installed at the Technological Research Institute of Sao Paulo. The characteristics of the process are first introduced. The mathematic modelling of the coiling system used, take into account the system components. The parametric changes were adressed. The control system was first implemented using a PID controller as this kind of control is highly used in the industry. An ultrasonic sensor was introduced in the system to improve the control precision by coiling radius measurement. Last a robust compensator using the LQG/LTR method was designed. The simulations were done using Matlab/Simulink software.

Melhorias na eficiência energética motivam o desenvolvimento de isolamentos térmicos cada vez mais eficazes e duráveis. Cerâmicas porosas à base de mulita (Al6Si2O13 ou 3Al2O3.2SiO2) são ideais para essa aplicação devido à alta resistência à corrosão e à densificação. Apesar de rara sua forma mineral, esta é uma das fases mais importantes em cerâmicas tradicionais e avançadas, visto que pode ser obtida a partir de fontes de alumina e sílica, por meio de diversas rotas de processamentos. Sua formação in situ por sinterização reativa tem se destacado dentre os métodos de produção pelos bons resultados mecânicos e eficácia na formação e manutenção de porosidade, entretanto, ainda existem pontos a serem investigados como a influência do tamanho de partícula e porosidade inicial de suas matérias-primas nas propriedades finais das estruturas. Neste trabalho, foram produzidas peças porosas de alumina-mulita in situ a partir de suspensões de sílica coloidal com diferentes concentrações (30, 40 e 50 %) e hidróxidos de alumínio de diferentes granulometrias (fino, HAF e grosso, HAG) pré-calcinados em várias temperaturas (500-1500 °C), pelo processo de moldagem direta para aplicação como isolante térmico em temperaturas acima de 1000 °C. As amostras (verdes e tratadas termicamente - 1500 °C) foram submetidas à ensaios mecânicos (módulo elástico e resistência à ruptura por compressão e flexão), análise microestrutural (MEV e DRX) e de propriedades físicas (porosidade total, densidades e variação térmica dimensional). As aluminas de transição provenientes da calcinação agiram como agentes porogênicos no sistema e juntamente com a sílica coloidal (com funções simultâneas de fluido de mistura, agente ligante, aditivo de secagem e fonte de SiO2 amorfa) formaram estruturas com grande variação de propriedades. Estruturas com HAF apresentaram porosidade próxima a 40% e elevadas propriedades mecânicas, e com HAG foram obtidos níveis de porosidade acima de 50 % e baixas resistências. As composições mistas, contendo tanto HAF como HAG, obtiveram bons resultados mecânicos e porosidades acima de 50 %, mostrando-se bons candidatos para uso como isolamento térmico. Todos os sistemas contiveram a fase de mulita em maior quantidade coexistindo com alfa alumina (Coríndon). / Improvements in energy efficiency motivate the development of more effective and durable thermal insulation. Porous ceramics based on mullite (Al6Si2O13 or 3Al2O3.2SiO2) have great potential for this application due its high resistance to corrosion and densification. Although rare in its mineral form, this is one of the most important phases in traditional and advanced ceramics because it can be obtained from alumina and silica sources, through various processing routes. Among them, the solid-state in situ reactions by reactive sintering stands out for its good mechanical properties and efficiency in the formation and maintenance of pores. However, how particle size and initial porosity of its raw materials influences the final properties still requires investigation. In this work, porous ceramics of alumina-mullite were produced in situ from aqueous suspensions of colloidal silica with different concentrations (30, 40 and 50 %) and aluminum hydroxides of different grain sizes (fine, HAF and coarse, HAG) pre-calcined in several temperatures (500-1500 °C) by direct casting process for application as a thermal insulation at temperatures above 1000 °C. The samples (green and thermally treated - 1500 °C) were submitted to mechanical tests (elastic modulus and resistance to rupture by compression and flexural), microstructural analysis (SEM and XRD) and physical properties characterization (total porosity, densities and dimensional thermal variation). The transition aluminas acted as porogenic agents in the system and with the colloidal silica (with simultaneous functions of mixing fluid, binding agent, drying additive and source of amorphous SiO2), formed structures with great properties\' variation. Samples with HAF had porosity close to 40% and high mechanical properties, and with HAG, porosity levels above 50 % and low resistances were obtained. The mixed compositions, containing both HAF and HAG, obtained good mechanical results and porosities above 50 %, showing great potential to thermal insulation. All systems contained most of mullite coexisting with alpha alumina phase (Corundum).

Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising clean technologies under development. However, the main obstacles for commercialising PEMFCs are largely attributed to the technical limitations and cost of current PEM materials such as Nafion. Novel poly(2,5-benzimidazole) (ABPBI)/POSS based polymer composite electrolyte membranes with excellent mechanical and conductivity properties were developed in this project including (I) ABPBI, polybenzimidazole (PBI) and their copolymers were synthesised by solution polymerisation and their chemical structures were confirmed by FTIR and elemental analysis. ABPBI/ActaAmmonium POSS (ABPBI/AM) and ABPBI/TriSilanolPhenyl POSS (ABPBI/SO) composites were also synthesised in situ. High quality polymer and composite membranes were fabricated by a direct cast method; and (II) The mechanical and thermal properties, microstructure and morphology, water and H3PO4 absorbility and proton conductivity of phosphoric acid doped and undoped ABPBI and ABPBI/POSS composite membranes were investigated. SEM/TEM micrographs showed that a uniform dispersion of POSS nano particles in ABPBI polymer matrix was achieved. The best performances on both mechanical properties and proton conductivities were obtained from the ABPBI/AM composite membrane with 3 wt% of POSS (ABPBI/3AM). It was found that both the water and H3PO4 uptakes were increased significantly with the addition of POSS due to formation of hydrogen bonds between the POSS and H2O/H3PO4, which played a critical role in the improvement of the conductivity of the composite membranes at temperatures over 100oC. ABPBI/3AM membranes with H3PO4 uptake above 117% showed best proton conductivities at both hydrous and anhydrous conditions from room temperature to 160oC, which is comparable with the conductivity of commercial Nafion 117 at 20oC in water-saturated condition, indicating that these composite membranes could be excellent candidates as a polymer electrolyte membrane for high temperature applications. A new mechanism for illustrating the improved proton conductivity of composite membranes was also developed.

A key challenge facing the nuclear fusion community is how to design a reactor that will operate in environmental conditions not easily reproducible in the laboratory for materials testing. Finite element analysis (FEA), commonly used to predict components’ performance, typically uses idealised geometries. An emerging technique shown to have improved accuracy is image based finite element modelling (IBFEM). This involves converting a three dimensional image (such as from X ray tomography) into an FEA mesh. A main advantage of IBFEM is that models include micro structural and non idealised manufacturing features. The aim of this work was to investigate the thermal performance of a CFC Cu divertor monoblock, a carbon fibre composite (CFC) tile joined through its centre to a CuCrZr pipe with a Cu interlayer. As a plasma facing component located where thermal flux in the reactor is at its highest, one of its primary functions is to extract heat by active cooling. Therefore, characterisation of its thermal performance is vital. Investigation of the thermal performance of CFC Cu joining methods by laser flash analysis and X ray tomography showed a strong correlation between micro structures at the material interface and a reduction in thermal conductivity. Therefore, this problem leant itself well to be investigated further by IBFEM. However, because these high resolution models require such large numbers of elements, commercial FEA software could not be used. This served as motivation to develop parallel software capable of performing the necessary transient thermal simulations. The resultant code was shown to scale well with increasing problem sizes and a simulation with 137 million elements was successfully completed using 4096 cores. In comparison with a low resolution IBFEM and traditional FEA simulations it was demonstrated to provide additional accuracy. IBFEM was used to simulate a divertor monoblock mock up, where it was found that a region of delamination existed on the CFC Cu interface. Predictions showed that if this was aligned unfavourably it would increase thermal gradients across the component thus reducing lifespan. As this was a feature introduced in manufacturing it would not have been accounted for without IBFEM.The technique developed in this work has broad engineering applications. It could be used similarly to accurately model components in conditions unfeasible to produce in the laboratory, to assist in research and development of component manufacturing or to verify commercial components against manufacturers’ claims.