Efeito da moagem de alta energia na densificação e microestrutura do compósito AI2O3-Cu
The Cu-Al2O3 composite ceramic combines the phase of alumina, which is extremely hard and durable, yet very brittle, to metallic copper phase high ductility and high fracture toughness. These characteristics make this material a strong candidate for use as a cutting tool. Al2O3-Cu composite powde...
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| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/19600 |
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| Resumo: | The Cu-Al2O3 composite ceramic combines the phase of alumina, which is extremely
hard and durable, yet very brittle, to metallic copper phase high ductility and high fracture
toughness. These characteristics make this material a strong candidate for use as a cutting
tool. Al2O3-Cu composite powders nanocrystalline and high homogeneity can be
produced by high energy milling, as well as dense and better mechanical structures can
be obtained by liquid phase sintering. This work investigates the effect of high-energy
milling the dispersion phase Al2O3, Cu, and the influence of the content of Cu in the
formation of Cu-Al2O3 composite particles. A planetary mill Pulverisatte 7 high energy
was used to perform the experiments grinding. Al2O3 powder and Cu in the proportion of
5, 10 and 15% by weight of Cu were placed in a container for grinding with balls of hard
metal and ethyl alcohol. A mass ratio of balls to powder of 1:5 was used. All powders
were milled to 100 hours, and powder samples were collected after 2, 10, 20, 50 and 70
hours of grinding. Composite powders with compact cylindrical shape of 8 mm diameter
were pressed and sintered in uniaxial matrix resistive furnace to 1200, 1300 to 1350 °C
for 60 minutes under an atmosphere of argon and hydrogen. The heating rate used was
10°C/min. The powders and structures of the sintered bodies were characterized by XRD,
SEM and EDS. Analysis TG, DSC and particle size were also used to characterize the
milled powders, as well as dilatometry was used to observe the contraction of the sintered
bodies. The density of the green and sintered bodies was measured using the geometric
method (mass / volume). Vickers microhardness with a load of 500 g for 10 s were
performed on sintered structures. The Cu-Al2O3 composite with 5% copper density
reached 61% of theoretical density and a hardness of 129 HV when sintered at 1300 ° C
for 1h. In contrast, lower densities (59 and 51% of the theoretical density) and hardness
(110 HV and 105) were achieved when the copper content increases to 10 and 15%. |
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