Page 31 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 307

technique. Zinc oxide nanorods prepared in
this SILAR facility are also being employed to
produce supercapacitors for energy storage
and several undergraduate students are en-
gaged in these investigations.

Copper based composites for electrical
application

Copper and its alloys have been used in func-
tion of the high thermal and electrical conduc-
tivity, good mechanical properties, resistance
Figure 38: Chemical-electric energy conversion device.
to corrosion, ease of fabrication and by the
high value of scrap. Metal alloys can also be Cermets based on rare earth oxides and metals
combined with other classes of materials to such as copper, silver and chromium) have
obtain new properties, superior to the origi- been studied (80% Cu – 20% CeO ; 80% Cu –
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nal alloy, this union of two or more materials 8% Cr – 4% Ag – 8% CeO ; 80% Cu – 20% Al O ;
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forms a composite. 80% Cu – 8% Cr – 4% Ag – 8% Al O ). The aim of
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this study involves microstructural character-
In this project copper alloys were developed ization (optical microscopy, scanning electron
by powder metallurgy for use in electrical microscopy, and X ray diffraction of composite
application, including fuel cell. The studied processed by powder metallurgy. The samples
composite has a ternary metal alloy (copper, used were fabricated in laboratory scale of 25
chromium and silver) as a matrix and a ceramic mm diameter, 3.5 mm ≥ h ≥ 4.0 mm of height
oxide (alumina or ceria) as the reinforcing and 6.5 g of mass.
phase. The addition of chromium, silver and
tin amounts of finely dispersed metal oxides To obtain the samples, the powders were
in copper improves their mechanical proper- weighed on a precision balance (according
ties and increases the operating temperature, to each composition), mixed manually and
causing little loss of conductivity. A possible cold-compacted in uniaxial press with 450 MPa
application of these composites is as anodes pressure and sintered in an EDG furnace under
in Solid Oxide Fuel Cells (SOFC) (Figure 38). 10-3 torr of mechanical vacuum and 650°C in

Figure 39: Optical micrographs of the composites Cu-Cr-Ag-(CeO , Al O ) in normal and transversal directions, as polished (100 µm scale).
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