Navegando Escola de Engenharia Mackenzie (EE) por Autor "Abreu, Claudio Domingos de"
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- DissertaçãoEstudo da dependência da condutividade com a microestrutura de ligas Cu-Ni com diferentes dopagensAbreu, Claudio Domingos de (2010-02-09)
Engenharia de MateriaisCopper and its alloys have various applications from manufactured artefacts to sophisticated equipments and stands out as conductive material due to high electrical and thermal conductivity. Its mechanical properties are moderate, as high corrosion resistance, high ductility. The choice of copper as a study material was motivated by the high consumption, since copper is the third most used metal in the world. Copper can be used alone or combined with other metal and depending on the concentration, can change it is characteristics. In situations where it is required greater mechanical strength, without changing its electrical and thermal properties, one or more elements cam be used in specific concentrations to achieve the desired result. In cast materials increase the percentage of alloying elements can cause a decrease in electrical conductivity. In the process of powder metallurgy the presence of porosity within a structure, indicates inadequate dissolution of the alloy elements, resulting in low electrical conductivity which cam be fixed with thermal treatment. In order to observe the dependence of the conductivity with the microstructure, Cu-Ni alloys were doped with Cr, Al, Sn and Pt. The metallic powder were mixed or and compressed in cold uniaxial pressure of 300 MPa. After that, the samples were sintered at temperatures between 700 and 800 º C for a period of 5400 seconds. The alloys were characterized by optical microscopy, electrical conductivity and Vickers hardness, infrared spectroscopy and x-ray diffraction. The conductivity results already achieved in materials prepared by the casting process and the resulting determined by powder metallurgy, there was a comparative study between these two technologies. It can be observed that the increase in cast materials of alloys and plastic deformation affect the electrical conductivity and powder metallurgy, the less porosity have the final material, the better the results of conductivity.