Estudo do efeito da moagem com a adição da alumina no metal duro
The WC-Co (carbide) composite, as well as the ceramic alumina are widely used as cutting tools in the metal-mechanic and petroleum, mining and civil construction industries due to their high hardness, high resistance to abrasion and under high temperature .This work investigates the addition of 1...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/32754 |
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| Resumo: | The WC-Co (carbide) composite, as well as the ceramic alumina are widely
used as cutting tools in the metal-mechanic and petroleum, mining and civil
construction industries due to their high hardness, high resistance to abrasion and
under high temperature .This work investigates the addition of 1, 2, 5 and 10% by
weight of Al2O3 to a cemented carbide powder (WC-Co) with 10% by weight of Co, the
effect of preparing the composite powders by manual mixing and high energy milling
and in addition, the influence of the sintering temperature on the density and
microstructure of the sintered compacts. A high-energy powder 7 planetary mill was
used to prepare all powders using a container with carbide balls and 99% ethyl alcohol
at 400 rpm for 50 h, except for the WC-10%Co powder with 5% by weight of Al2O3
which also had a powder charge milling for 30 h. Powder samples were collected after
2, 6, 10, 20 and 30 h during milling and by manual mixing to serve as a reference.
Green compacts with 5.04 ± 0.2 mm in diameter were pressed to 200 MPa in a uniaxial
cylindrical stainless-steel matrix. These were sintered in a dilatometer at 1400 °C and
1550 °C for 1 h under an argon atmosphere and a heating rate of 10 °C/min. All
powders and sintered compacts were characterized using particle size distribution
techniques, XRD, SEM, EDS, measures of density, densification, dilatometric
contraction and Vickers hardness. The compacts of composite powders WC-10% CoAl2O3 with addition of 5 and 10% of Al2O3 exhibit higher density and densification under
higher temperature, however the maximum density achieved was 70% of the
theoretical density both when milling for 50 h and for mixed for 10 minutes. However,
compacts of composite powders WC-10%Co-5%Al2O3 milling for 30 h sintered at 1550
°C exhibit denser microstructures with a density of 91% and a densification of 87%, in
addition to a hardness of 500 HV. |
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