Densificação e microestrutura de um compósito Mo-Cu preparado a partir de um pó de heptamolibidato de amônia e cobre
The Cu-Mo system is a composite used in the electrical industry as material for electrical contact and resistance welding electrode as well as the heat sink and microwave absorber in microelectronic devices. The use of this material in such applications is due to the excellent properties of therm...
Na minha lista:
| Autor principal: | |
|---|---|
| Outros Autores: | |
| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
|
| Assuntos: | |
| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/19480 |
| Tags: |
Adicionar Tag
Sem tags, seja o primeiro a adicionar uma tag!
|
| Resumo: | The Cu-Mo system is a composite used in the electrical industry as material for
electrical contact and resistance welding electrode as well as the heat sink and microwave
absorber in microelectronic devices. The use of this material in such applications is due to the
excellent properties of thermal and electrical conductivity and the possibility of adjustment of
its coefficient of thermal expansion to meet those of materials used as substrates in the
semiconductor micoreletrônic industry. Powder metallurgy through the processes of milling,
pressing shaping and sintering is a viable technique for consolidation of such material.
However, the mutual insolubility of both phases and the low wettability of liquid Cu on Mo
impede its densification. However, the mutual insolubility of both phases and the low
wettability of liquid Cu on Mo impede its densification. The mechanical alloying is a
technique for preparation of powders used to produce nanocrystalline composite powder with
amorphous phase or extended solid solution, which increases the sinterability immiscible
systems such as the Mo-Cu. This paper investigates the influence of ammonium
heptamolybdate (HMA) and the mechanical alloying in the preparation of a composite
powder HMA-20% Cu and the effect of this preparation on densification and structure of MoCu
composite produced. HMA and Cu powders in the proportion of 20% by weight of Cu
were prepared by the techniques of mechanical mixing and mechanical alloying in a planetary
mill. These were milled for 50 hours. To observe the evolution of the characteristics of the
particles, powder samples were taken after 2, 10, 15, 20, 30 and 40 hours of milling.
Cylindrical samples 5 to 8 mm in diameter and 3 to 4 mm thickness were obtained by
pressing at 200 MPa to the mixed powders so as to ground. These samples were sintered at
1200 ° C for 60 minutes under an atmosphere of H2. To determine the effect of heating rate
on the structure of the material during the decomposition and reduction of HMA, rates of 2, 5
and 10 ° C / min were used .. The post and the structures of the sintered samples were
characterized by SEM and EDS. The density of the green and sintered bodies was measured
using the geometric method (weight / volume). Vickers microhardness with a load of 1 N for
15 s were performed on sintered structures. The density of the sintered structures 10 ° C / min.
reached 99% of theoretical density, how the density of sintered structures to 2 ° C / min.
reached only 90% of the theoretical density |
|---|