Dissertações em Engenharia Mecânica (Mestrado) - PPGEM/ITEC
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2342
O Mestrado Acadêmico pertence ao Programa de Pós-Graduação em Engenharia Mecânica (PPGEM) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).
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Navegando Dissertações em Engenharia Mecânica (Mestrado) - PPGEM/ITEC por Orientadores "QUARESMA, José Maria do Vale"
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Item Acesso aberto (Open Access) Análise da influência dos solutos Zr e Ti sobre as propriedades mecânica, elétrica e de termorresistência de uma liga Al-Cu-Fe-Si destinada a Tx e a Dx de energia elétrica(Universidade Federal do Pará, 2012-01-10) MACHADO, Paulo Cordeiro; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290The global energy context presents a steady increase in electricity consumption in the last century, thus requiring the search for new materials for use in wire and cable conductors of electricity. From these demands for new materials, was developed an analysis of the influence of solute titanium and zirconium in the modification of important characteristics of the Al-Cu-Fe-Si alloy, destined to be the middle conductor of electricity, aiming to get properties resistant to heat. For this study, the alloys were obtained by direct casting in Ushaped metal ingots, from the Al-EC, standing at the base levels of 0.05 wt% Cu, [0.24 to 0.28] wt% Fe and 0.7 wt% Si, and then inserting the contents of 0.26 wt% Zr and 0.26 wt% Ti. The experiments were, divided in two steps, STEP A and STEP B , respectively. In order to characterize mechanical, electrical and structure of alloys. The specimens after cold rolling (in diameters of 2.7, 3.0, 3.8 and 4.0 mm) were analyzed without heat treatment (STT) and with heat treatment (CTT): 230 °C for one hour, according to the protocol COPEL (Companhia Paranaense de Energia Elétrica), 310 °C and 390 °C for one hour, to evaluate the heat resistance at higher temperatures, thermal stability and analyze the microstructures developed in these heat treatments (TT). It was found that Ti has more capacity to refine the grain compared to Zr, which has less refined grains, but with better physical properties are presented and heat resistant.Item Acesso aberto (Open Access) Avaliação das propriedades mecânicas e elétricas da liga 6201 não refinada, modificada com os teores de cobre (0,05 e 0,3)% para transporte de energia elétrica(Universidade Federal do Pará, 2009-03-27) VENTURA, Odila da Silva Passos; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290At the present work, experiments were made with the unrefined alloy Al – 0,6%Mg - 0,8%Si, with variations in copper content (0,05% e 0,3%), that aimed to evaluate two aspects of the alloy behavior. The first aspect concerns the affinity between it and the mold, which seeks to observe the effect of the solidification thermal variables of the structure of molten and the correlation with mechanical and electrical properties, the second aspect is related with the intrinsic behavior of the variation on the chemical composition subject at low speed and cooling rates. For evaluating the solidification thermal variables (liquidus isotherms velocities, cooling rates) was used a device for horizontal unidirectional solidification. The ingots produced from the solidification of the alloy rose by mechanical machining, laminating and steel drawing, examined in different positions and diameters, by testing the traction and electric conductivity. Fractures were analyzed in terms of micro cavities and different levels of copper and it was found that in the cold deformed material, the limit of tensile strength has a trend of growth for the alloys of higher concentration of copper. The measured values have also concluded that the electrical conductivity increases the greater the diameter of the micro cavities and lower the copper content. In order to evaluate only the intrinsic variation behavior of the alloy chemical composition, a second device was used for solidification, mold in "U", painted internally in solution of kaolin that attaches to such low rates of cooling. The results show that for both copper content there is a tendency of increase in the limit of tensile strength with increasing reduction suffered by the samples, the limit of tensile strength greater for the alloy with higher copper content. We attach this behavior to the higher content of solute which in turn showed better response to plastic deformation, compressing the material. However, the electrical characterization occurs in an opposite way, as seen in unidirectional solidification, where the lowest copper content was more efficient.Item Acesso aberto (Open Access) Caracterização da liga 6101 refinada com a adição de diferentes teores de cobre e solidificadas em molde unidirecional horizontal e em molde "U"(Universidade Federal do Pará, 2007) FEITOSA, Johnyson Pereira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290The 6101 alloy (series 6xxx) was modified with addition of 0.05% and 0.3% of copper and with additions of grain refiners as Al-Ti-B. The alloys were thermally characterized (heat transfer coefficient of metal / mold, displacement speed of liquidus isothermal and cooling rate), mechanically (tensile strength and toughness module) and electrically (electric resistivity, specific resistance and power conductivity) using two forms of pouring out: one is horizontal directional solidification and the other into the "U" mold. By horizontal directional solidification was possible characterize the macrostructure, influenced by refiners of grain and by viscosity that copper provides in the metal / mold efficiency of alloys researched, modifying the thermal, mechanical and electrical properties. The solidification in "U" mold makes possible evaluates the mechanical and electrical properties, seeing the forming process variables of alloys, as forming rate, tensile strength, toughness and electric resistivity, power conductivity and electric resistance, using the specimens obtained in several diameters. For the “U” mold were casting more two alloys to evaluation, Al-0,6Mg-0,4Si-0,1Cu and Al-0,6Mg-0,4Si-0,2Cu. The mechanical and electrical properties had been influenced by cold working, copper content and shrinkage void presents into alloys structures.Item Acesso aberto (Open Access) Correlação da coalescência de microcavidades com as propriedades mecânicas e elétricas de fios para Tx e Dx de energia elétrica da liga base Al-0,5%Cu-[0,24-0,28]%Fe modificada com teores de silício(Universidade Federal do Pará, 2013-07) MONTEIRO, Valmor Capanema Oliveira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290In this study, na attempt is made to establish the influence of the concentration [0.5, 0.7 and 0.9]% Si as modifiers of alloys Al-0,05% Cu-[0.24 to 0.28]%Fe, evaluated by aspects that took into account operational parameters such as horizontal unidirectional leaks: Speeds (Vs) and Exchange Solidification (Tx). After cutting and machining cylindrical profiles were obtained with diameters of 9.5mm and length of 120mm, from which, after the cold working operations, were obtained wires with diameters of 2.7, 3.0, 3.8 and 4.0 mm. These profiles were subjected to electrical characterization on the basis of the electrical conductivity, tomechanical characterization based on assays stress/strain, emphasizing elongation [%], and structural characterization longitudinal sections, with emphasis on distribution of second phase particles, and aspect of the fracture, with emphasis on the relationship L/W length (L) and width (W) of the dimples.Item Acesso aberto (Open Access) Efeito de adições de Ni e Mg sobre o comportamento térmico, mecânico e elétrico de ligas Al-Cu-Fe solidificadas unidirecionalmente(Universidade Federal do Pará, 2013) SOUZA, Pedro Henrique Lamarão; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290This work studied the influence of Mg and Ni solute content on the modification of the thermal, electrical and mechanical properties of an Al-Cu-Fe alloy for application as an electrical conductor. To realize the present study, the alloys were obtained by unidirectional horizontal casting, starting from the commercial pure aluminum with the addition of 0.05wt% Cu and [0.24 to 0.28]wt% Fe content. This basis was modified on a first stage with 0.45, 0.60 and 0.80wt% of Mg content. The alloys obtained with these contents had its properties studied for the selection of a Mg content for further Ni addition at the alloy. The study of these properties on the first stage passed through the analysis of the thermal properties: growth rate (VL) and cooling rate (Ṫ). The electrical characterization studied the electrical conductivity property (φ) and the following mechanical properties were determined: ultimate tensile strength (σ) and Vickers microhardness (HV). The alloy which has Ni additions passed through ageing heat treatments of 1, 4 and 8 hours. These samples were analyzed in a scanning electron microscope – SEM by the electrons backscattered – EBS and energy dispersive spectroscopy – EDS signals. As a result of the research, it was found that Mg additions had significantly influenced the alloys viscosity, increasing its growth rates at the final moments of the solidification. The microhardness tests for the aged samples showed that they suffered a significant gain of hardness at the fourth hour of ageing, also, the EDS analysis showed that Ni content increased at the same treating conditions.Item Acesso aberto (Open Access) Efeito de teores de Zr sobre as propriedades mecânicas e elétricas de ligas Al-Ec-Si aplicadas na elaboração de ligas para Tx e Dx de energia elétrica(Universidade Federal do Pará, 2010) SANTOS, Washington Luis Reis; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290This paper aims to develop an analysis of the influence of Zr in the modification of important characteristics of Al-EC-Si alloys used in electrical conductors, aiming to obtain heat resistant properties. For this study, the alloys were obtained by direct casting in a U-shaped ingot mold, from the Al-EC, with a base Si content of 0,7%, and then varying with different amounts of Zr. Intending o precipitate second phase particles called dispersoid, whose main characteristic is the retention of the deformed microstructure when exposed to high temperatures, it was necessary to submit the alloys to a heat treatment of 310 ºC for 24 hours in order to cause the appearance of fine dispersoids of Al3Zr. Two steps were established to obtain the results: The Step I was composed of solidification, machining and deformation obtained with the alloys, generating the wires used in all tests. The Step II repeats the same processes adopted in the Step I, however a heat treatment of 310 ºC for 24 hours was made before deformation. The heat resistance characterization of the specimens of each alloy followed the requirements of COPEL (Companhia Paranaense de Energia Elétrica ) when submitted to temperatures of 230 ºC for 24 hours, and heat treatments at temperatures of 310 ºC and 390 ºC were also made to evaluate the thermal stability of the alloys. In general, it was observed that crescent contents of Zr results in a grain refinement and a increase of the Ultimate Tensile Strength and thermal stability of the alloy, both in the Step I and Step II. It was also observed that in Step I, the electrical conductivity was severely affected by the Zr contents and the addition of heat treatment in Step II increased the electrical conductivity of the alloy, particularly to diameters that suffered higher deformation.