Made available in DSpace on 2014-10-09T12:43:05Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:43Z (GMT). No. of bitstreams: 1 06123.pdf: 4547052 bytes, checksum: 48ec616978a4d951011d14b673b5caa2 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:27:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:28Z (GMT). No. of bitstreams: 0 / Energia é um recurso que historicamente apresenta tendência de crescimento de demanda. Projeções indicam que, para suprir as necessidades energéticas do futuro, será necessário um uso massivo do hidrogênio como combustível. O uso de sistemas de célula a combustível baseada no uso de membrana polimérica condutora de prótons (PEMFC) tem características que permitem sua aplicação para geração de energia elétrica em aplicações estacionárias, automotivas e portáteis. O uso de hidrogênio como combustível para PEMFC apresenta a vantagem de resultar em baixa emissão de poluentes quando comparado às dos combustíveis fósseis. Para que ocorram as reações em uma PEMFC é necessária a construção de conjuntos eletrodo-membrana-eletrodo (MEA), sendo o processo de produção de MEAs e os materiais utilizados, relevantes no custo final do kW instalado para geração de energia por sistemas de célula a combustível, o que é, atualmente, uma barreira tecnológica e financeira para a aplicação em grande escala desta tecnologia. Nesse trabalho foi desenvolvido um processo de produção de MEAs por impressão a tela que apresenta alta reprodutibilidade, rapidez e baixo custo. Foram desenvolvidos o processo de impressão a tela e a composição de uma tinta precursora da camada catalisadora (TPCC), que permitem o preparo de eletrodos para confecção de MEAs com a aplicação da massa exata de eletrocatalisador adequada para cátodos 0,6 miligramas de platina por centímetro quadrados (mgPt.cm-2) e ânodos 0,4 mgPt.cm-2 em apenas uma aplicação por eletrodo. A TPCC foi desenvolvida, produzida, aplicada e caracterizada, apresentando características semelhantes a de tintas de impressão a tela para outras aplicações. Os MEAs produzidos apresentaram desempenho de até 712 mA.cm-2 a 600 mV para MEAs de 25 cm2 e o custo para produção de MEAs de 247,86 cm2 capazes de gerar 1 kW de energia foi estimado em R$ 13.939,45, considerando custo de equipamentos, materiais e mão de obra. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

A hot isostatic press (HIP) is a system which utilises high temperatures and pressure in order to densifyand enhance the material properties of components in the aerospace, automotive and additive manufacturingindustries, to mention a few. Quintus is a world leading manufacturer of HIP systems, and this master’s thesiswork has been written in collaboration with them. A HIP consists of a cylinder which gets filled with an inert gas, a gas which is then pressurised using compressors.Inside of the cylinder are heaters which ensure that the gas and load reach the desired temperature. Quintus’HIP construction has a wire wound cylinder. This means that a pre-stressed wire is wound around the cylinderfor a number of laps, resulting in the cylinder always being in a compressive stress state, thus ensuring a safeconstruction if a crack were to propagate in the material. This construction also allows for a more slim design ofthe cylinder which is beneficial when the gas is to be cooled, as the heat gets transported through the cylinder.An alternative design to this wire wound cylinder is a so called monoblock cylinder. This is a solid, thicker,cylinder, not wound by any wire. Quintus does not manufacture the monoblock HIP system, but these HIPs areon the market and therefore Quintus is keen to learn more about them. In this work, differences in the cooling capabilities with respect to the cylinders’ strength has been investigated,regarding the wire wound and monoblock cylinders. This has been done by the means of CFD and FEM(ANSYS CFX and ANSYS Mechanical), where a simplified 2D axisymmetric model of each HIP version wasused. In CFX, both a steady state and transient simulation was run for each model in order to capture the coolingof the gas. The resulting temperature load on the cylinder was then exported to the Mechanical setup to solvefor the arising stresses of the cylinders. The results of the work showed that the wire wound HIP does indeed exceed the monoblock cylinder when itcomes to the cooling rate, especially after some time when the gas has cooled off. Neither one of the cylinderswere at risk of yielding, and the monoblock cylinder was calculated to withstand >20 000 cycles, which is alsothe fatigue life of the wire in Quintus’ HIPs. The models and boundary conditions used in this work weresubjected to approximations, but the results obtained have still brought a lot of new insights to the monoblockconstruction, and have provided a good foundation for further analyses.

This diploma thesis is focused on preparation of Mg-Al based bulk materials via powder metallurgy. The bulk materials were prepared by cold pressing, cold pressing followed by sintering, cold pressing followed by sintering and artificial aging, SPS (spark plasma sintering), SPS followed by solution annealing, SPS followed by solution annealing and artificial aging. The prepared materials were characterized in terms of microstructure and physical and mechanical properties. The properties of the prepared materials differed depending on the method of preparation and Al content. All materials after heat treatment were consisted of solid solution (Mg), intermetallic phase Mg17Al12 and MgO. The composition of the materials depended on Al content. Sintering by the SPS method resulted in material with better mechanical properties compared to materials whose first step of preparation was cold pressing.

This project concentrates on the technology of manufacturing of the plastic socket outlet. It consists of two parts, where the first part is a literature study. Here are described the characteristics of the materials and their specifications. Further on is described basic knowledges technical methods of injection and some other technologies. The second section consists of the right proposal of the material. Further on in this section is described technological treatment. Mechanical function and its design and technical drawing are a part of this second section. As a final result is a brief comparison of the technology between the injection or pressing into molds. Herewith is also included a simplified financial budget calculation.

This diploma thesis is about designing vacuum pressing device for plastics as an important method of manufacturing semi-finished plastic products. In introduction part of this thesis there is described a process of this method, the application field among the another plastics processing technologies, basic information about using semi-finished products and moulding forms. There are three versions of solution. After the estimation of this versions there is a decision about a final form vacuum pressing device. One’s own design work contains a project of a device like this with the help of Autodesk Inventor CAD system. In the end of the work, there is financial balance-sheet too.

The aim of this thesis is constructional concept of diaphragm press for thermoplastic forming. The press consists of two chambers. First chamber is designed for forming of semi-finished product to forming temperature and second chamber is designed for heating the semi-finished product. Theoretical part of this thesis is focused on technologies in use and shaping of plastic description. Practical part of this thesis deals with detailed description of press concept including consistence calculations and drive units calculations. The whole concept, including its individual parts, is designed using the Autodesk Inventor software. At the end of this thesis, there is the economic and safety analysis.

Increased understanding of the mechanisms that operate in conjunction with the welding of metal surfaces may help to improve existing manufacturing processes, and to enable new products and combinations of materials. The purpose of the project has therefore been to acquire a deeper understanding of what is happening in the bond for steel and for the factors that form the basis for a bond to develop between metals in the production of laminates by pressing. The merge has been done by pressing and the surfaces after the experiments have been studied in detail in the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and with interferenceprofilometry in Wyko, to provide a greater understanding of the mechanisms that influence the bonding in the interface between metals.   The project was limited to contain the materials Docol 1000, HyTens 1200, Aluminum AA3003 and a commercial steel. The parameters varied in the experiments to study their influence closer are temperature, pressure, heat treatment and pretreatment. This has been implemented by pressing with varying temperature and pressure. The materials have been pressed at room temperature or heated in an oven at 300 or 600 degrees and pressed immediately after the levying. Pretreatment was done by cleaning in acetone followed by either brushing or sandblasting alternatively no pretreatment have been done at all. The result was that the increased pressure and increased temperature increases the chance of joining by pressing. Pressing at slightly elevated temperature (about 100-250 degrees, depending on the material) makes bonding possible for metals which are not joined together at room temperature. Pretreatment by sandblasting gives a rougher and more riddled surface than brushing. At the cracking in the oxide layer at the pressing, wells new clean metal into between the oxides to the surface. When the new material reaches the surface, a joint can be made with the opposite clean material. The clean metal that wells up, then flows in a pattern which presses down the oxide in the material, away from the surface. This is done so more clean material can come to the surface and a finer binding can be obtained.

More efficient and cheaper solar cells are necessary if photovoltaics are to play a major rolein the field of sustainable power generation. Copper indium gallium selenide (CIGSe) is one of the best suited materials for thin film solar cell absorbers. One production method for thin film manufacturing is sputtering, a fast, high-yield, all-dry process that can be performed in an unbroken vacuum chain. The sputter target, which provides the raw material for this process, is an important link to obtain high quality films. Furthermore, the targets stands for the single largest cost in solar cells produced through the method. Hence, driving down the target production costs while maintaining or increasing quality is a vital route towards competitive photovoltaic power generation. In this project, compound CIGSe sputter target material was produced via mechanical alloying of elemental raw materials, followed by hot pressing. The resulting material obtained a relative density above 90% in all samples, with close compositional matching and grain sizes between 20-50 µm. Electrical characterization indicated predominantly p-type majority carriers, and the resistivity was within the range of industrially produced targets. Suitable process parameters are suggested as follows: for ball milling; 600rpm rotational speed, a ball-to-powder ratio of 5:1, and a milling time of 60-120 min. For pressing: 650-750˚C peak temperature, maintained for 1-2 h under 25-60 MPa pressure. 30 min dwell time at peak temperature before pressure application was found to reduce porosity. An initial composition of 23.2/20/6.5/50 at% of Cu, In, Ga, and Se, respectively, was found appropriate to obtain a final composition close to 22.8/20/7/50.2 at%. The project has proven that mechanical alloying combined with hot pressing provides a promising route towards efficient sputter target manufacturing, where the reduction of process operations compared to conventional manufacturing methods entails an optimistic economic outlook.

Equal-channel angular pressing (ECAP) is one of the severe plastic deformation (SPD) to produce ultra-fine grain (UFG) material, and its principle and microstructural developments. The majority of papers on SPD materials have been devoted to the face centered cubic (FCC) structure materials such as Al, Cu and Ni. The UFG of high alloy ECAP processing has been difficult up to now, but we were successful in this study. Fe-20%Cr steel with extremely low C and N has different slip behavior from the FCC. The mechanical properties and corrosion resistance were investigated in term microstructural evolution during ECAP processing. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University