Endurecimento do pó de cobre com carbeto de tungstênio via moagem de alta energia
The use of composite materials has been growing on a large scale in recent years due to obtaining a product with important properties and with different fields of application. The composites produced with a copper matrix and reinforced with a ceramic material and refractory are of great importanc...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/48779 |
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| Resumo: | The use of composite materials has been growing on a large scale in recent
years due to obtaining a product with important properties and with different fields of
application. The composites produced with a copper matrix and reinforced with a
ceramic material and refractory are of great importance, due to its various applications
in electrical conductors and heat sinks. In this sense, the work aimed to investigate the
hardening of copper powder (Cu) with the addition of tungsten carbide (WC) through
high energy milling (HEM) in order to evaluate the influence of WC percentage and
grinding time on copper powder properties. The HEM of the powders was performed
in liquid medium at 400 rpm for 1, 2, 5, 10 and 20 hours, using a mass ratio of powder
to balls of 1:4. Then, the obtained powders were characterized with Scanning Electron
Microscopy (SEM), X-Ray Diffraction (XRD) and Vickers microhardness. The results
obtained showed that the high energy milling method used in this work proved to be
efficient for obtaining Cu-WC, since the cyclic collisions of the HEM exert surface
modifications in the powders through the processes of plastic deformation, cold
welding and fracture, generating defects and, consequently, the formation of
composite particles occurs. Besides that, it was found that the milling time was an
important factor to obtain a greater dispersion and homogenization of the powder
particles. The XRD technique allowed to verify that the composite powders did not
present peaks referring to the secondary phases. Finally, it is noted that the Vickers
microhardness value is directly related to the amount of WC and with the grinding time,
since that, the composites of Cu-20%WC milled with different times present the higher
results for microhardness when compared with the other compositions. Therefore, the
composite powder with 20%WC milled for 20 hours presented a hardness of 250.50
HV, surpassing the values of the other powders. |
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