Faculdade de Engenharia Mecânica - FEM/ITEC
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2551
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Navegando Faculdade de Engenharia Mecânica - FEM/ITEC por Autor "DIAS FILHO, José Marcelino da Silva"
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Item Acesso aberto (Open Access) Characterization of the Al-3wt.%Si alloy in unsteady-state horizontal directional solidification(2013-08) CARVALHO, Diego de Leon Brito; GUIMARÃES, Emanuelle Casseb; MOREIRA, Antonio Luciano Seabra; MOUTINHO, Daniel Joaquim da Conceição; DIAS FILHO, José Marcelino da Silva; ROCHA, Otávio Fernandes Lima daThe main purpose of this paper is to investigate both the columnar to equiaxed transition and primary dendritic arm spacings of Al-3wt.%Si alloy during the horizontal directional solidification. The transient heat transfer coefficient at the metal-mold interface is calculated based on comparisons between the experimental thermal profiles in castings and the simulations provided by a finite difference heat flow program. Simulated curve of the interfacial heat transfer coefficient was used in another numerical solidification model to determine theoretical values of tip growth rates, cooling rates and thermal gradients that are associated with both columnar to equiaxed transition and primary dendritic arm spacings. A good agreement was observed between the experimental values of these thermal variables and those numerically simulated for the alloy examined. A comparative analysis is carried out between the experimental data of this work and theoretical models from the literature that have been proposed to predict the primary dendritic spacings. In this context, this study may contribute to the understanding of how to manage solidification operational parameters aiming at designing the microstructure of Al-Si alloys.Item Acesso aberto (Open Access) Espaçamentos dendríticos primários da liga Sn-5%Pb solidificada direcionalmente em um sistema horizontal(2012) NOGUEIRA, Márcio Roberto Alves; CARVALHO, Diego de Leon Brito; MOREIRA, Antonio Luciano Seabra; DIAS FILHO, José Marcelino da Silva; ROCHA, Otávio Fernandes Lima daIn order to investigate the effect of thermal parameters on the primary dendritic spacings of Sn - 5%Pb alloy, horizontal directional solidification experiments have been carried out under unsteady state heat flow conditions. Thermocouples have been connected with the metal, and the time - temperature data have been recorded automatically. The results include metal/mold heat transfer coefficient determined from comparisons between the experimental thermal profiles and simulations provided by a numerical model. A combined theoretical and experimental approach is developed to determine the solidification thermal parameters: tip growth rates, and cooling rates. The experimental and calculated values have shown a good agreement. A comparative study between experimental data of this work and those from the literature proposed to predict the primary spacings during upward and downward vertical unsteady-state directional solidification of Sn - Pb alloys is presented. The observation of the microstructures has indicated that the primary dendritic spacings have been affected by the direction of growth, increasing in conditions of horizontal solidification when compared with those obtained during vertical solidification.Item Acesso aberto (Open Access) Influência das variáveis térmicas sobre os espaçamentos dendríticos terciários durante a solidificação direcional horizontal da liga Al-6%Cu(2015-03) DIAS FILHO, José Marcelino da Silva; KIKUCHI, Rafael Hideo Lopes; COSTA, Thiago Antônio Paixão de Sousa; MOREIRA, Antonio Luciano Seabra; ROCHA, Otávio Fernandes Lima daThe Al-6wt%Cu alloy was directionally solidified and dendritic microstructure, solidification thermal variables, i.e., tip growth rate (VL), cooling rate (TR) and temperature gradient ahead of liquidus isotherm (GL) were characterized and correlated with tertiary dendritic spacings (λ3) determined experimentally. For this purpose, a horizontal solidification experimental apparatus was developed and specimens were solidified under unsteady state heat flow conditions. It was observed that power laws -1.1 and -0.55 characterize the tertiary spacing variations with tip growth rate (VL) and cooling rate (TR), respectively. Comparisons with other studies published in the literature for Al-Cu alloys solidified in upward and downward vertical directional conditions were performed.Item Acesso aberto (Open Access) Solidification thermal parameters and dendritic growth during the horizontal directional solidification of Al-7wt.%Si alloy(2014-09) CARVALHO, Diego de Leon Brito; COSTA, Thiago Antônio Paixão de Sousa; MOREIRA, Antonio Luciano Seabra; SILVA, Maria Adrina Paixão de Souza da; DIAS FILHO, José Marcelino da Silva; MOUTINHO, Daniel Joaquim da Conceição; ROCHA, Otávio Fernandes Lima daThe main purpose of this work is to investigate the influence of thermal parameters such as growth rate (VL) and cooling rate (TR) on the primary dendrite arm spacings (λ1) during the horizontal transient directional solidification of Al-7wt.%Si hypoeutectic alloy. The primary dendrite spacings were measured along the length of the samples and correlated with these thermal parameters. The variation of dendrite spacings is expressed as a power law function of VL and TR given by the formulas λ1 = 55(VL)-1.1 and λ1 = 212 (TR)-0.55, respectively. A comparative study between the results of this work and those from the literature proposed to investigate these dendrite spacings during the upward and downward vertical directional solidification of Al-7wt.%Si alloy is also conducted. Finally, the experimental data are compared with some predictive dendritic models from the literature.Item Acesso aberto (Open Access) The columnar to equiaxed transition of horizontal unsteady-state directionally solidified Al-Si alloys(2014-04) CARVALHO, Diego de Leon Brito; MOREIRA, Antonio Luciano Seabra; MOUTINHO, Daniel Joaquim da Conceição; DIAS FILHO, José Marcelino da Silva; ROCHA, Otávio Fernandes Lima da; SPINELLI, José EduardoExperiments were conducted to investigate the influence of thermal parameters on the columnar to equiaxed transition during the horizontal unsteady-state directional solidification of Al-Si alloys. The parameters analyzed include the heat transfer coefficients, growth rates, cooling rates, temperature gradients and composition. A combined theoretical and experimental approach is developed to determine the solidification thermal variables considered. The increasing solute content in Al-Si alloys was not found to affect significantly the experimental position of the CET which occurred for cooling rates in the range between 0.35 and 0.64 K/s for any of three alloy compositions examined. A comparative analysis between the results of this work and those from the literature proposed to analyze the CET during upward vertical solidification of Al-Si alloys is reported and the results have shown that the end of the columnar region during horizontal directional solidification is abbreviated as a result of about six times higher thermal gradient than that verified during upward unidirectional solidification of alloys investigated.