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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Item Acesso aberto (Open Access) Determinação do calor específico de ligas AlCu produzidas em um dispositivo de solidificação unidirecional vertical ascendente(Universidade Federal do Pará, 2008-11-24) MARTINS, Marcelo Gonçalves; SÁ, Fernando Antonio de; http://lattes.cnpq.br/8275621144223544The knowledge of the properties of the thermophysics is extremely important to the study of the metallic alloys obtained from the solidification, once this one it is directly related to the heat transfer coefficient at the metal / mold interface. Thus, the researchers group of metallurgy and environment – GAPEMM of Federal University of Pará develops a line of research that proposes to develop techniques and procedures which has as main objective to determine them. On the other side, it is known that there is a significant correlation among process, structure, and properties obtained from a material during solidification. Since the distribution of solute in a metallic alloy occurs in a heterogeneous way. The way the solidification happens and the quantification of the varieties involved in the process has fundamental influence in the properties of the material. The present study used alloys Al-Cu (Al-2%Cu, Al-5%Cu e Al-8%Cu) obtained from a process upward directional solidification, made through one dispositive planned, constructed and calibrated by gapemm. Through these researches, there’s the intention to study the specific heat as it gets away the plate mold as well as the raise of the solute content. To do this, it was used a technique known in the literature as the Newton´s law cooling, which makes it possible through the curves of temperature x time to determine the necessary temperatures that will allow the calculation of the specific heat.Item Acesso aberto (Open Access) Variáveis térmicas de solidificação, espaçamento dentríticos secundários e resistência à corrosão de ligas hipoeutéticas Al-Ni(Universidade Federal do Pará, 2008-08-14) COSTA, Giselle Barata; SÁ, Fernando Antonio de; http://lattes.cnpq.br/8275621144223544In this research is carried out a sequence of experiments with Al-Ni hypoeutectic alloys to analyze the upward vertical directional solidification on transient conditions of heat flow. Experimental approaches were developed to quantitative the thermal variables of solidification, as follow: local time solidification; dislocation rate of liquidus isotherms, tip cooling rates and thermal gradients. This study analyzes the dendrite secondary arms spacing in relation to solidification thermal variables and to alloy composition, beyond link these parameters with corrosion resistance of these alloys. These experimental dendrite parameters, concerning to alloys solidification as Al - 1, 1,4 and 1,8%Ni, couldn’t be compared with the main theoretical model of dendrite growth by others researches, because, to alloy studied there shortage of thermophysic properties, impossible this comparison. The corrosive behavior is analyzed by potentiodynamic polarization technique and cyclic polarization technique lead into 3,5%NaCl solution on room temperature, coarse structure dendritics tend to increase the corrosion rates of Al-Ni hypoeutectic alloys. The experimental results obtained by the corrosion tests were correlated with dendrite microstructure. This way, experimental tendencies of growth dendrite were determined to upward vertical directional solidification.