The miniaturization of Microtechnology-based Energy, Chemical and
Biological Systems (MECS) is made possible by the use of high aspect ratio
microchannel arrays to increase the surface-area-to-volume ratio of the flow
conduits within the devices, resulting in an improvement in the heat and mass
transfer performance of the devices. However, advantages of the MECS concept
cannot be applied to high-temperature applications (above 650��C) due to lack of
high-temperature MECS devices; therefore, the development of high-temperature
MECS devices is necessary to overcome this bottleneck. This dissertation involves
the development of high-temperature MECS devices from a high-temperature
material, nickel aluminide (NiAl). NiAl foil was synthesized from elemental nickel
(Ni) and aluminum (Al) foils through a two step process--tack bonding and
reactive diffusion. The elemental foils were tack bonded at 500��C, 3.9 MPa for
15 minutes. The reactive diffusion process was then performed through a heat
treatment at 1000��C for a period of time corresponding to the thickness of the
composite foil. The synthesized NiAl foil showed an atomic ratio of Al to Ni up to
0.96. The foil also showed a decent flatness and surface roughness. This
dissertation proposes a reactive diffusion bonding as a joining technique of nickel
aluminides. An investigation of bonding parameter effects on the warpage of
nickel aluminide fins in the reactive diffusion bonding process was performed.
Results showed that bonding time and temperature had significant effects on
warpage of the fin. The fin warpage increased with the increase of bonding time
and bonding temperature. Results also suggested that the bonding pressure had an
effect on the fin warpage. However, chemical compositions of the fin were not
significant to the warpage. This research also proposes a new fabrication procedure
for producing NiAl MECS devices. NiAl foils were used as the starting material,
and the reactive diffusion bonding technique was employed as the joining
technique. The research outcome indicated the viability of the proposed method in
fabricating NiAl MECS devices. This method achieved leak-tight devices with a
reasonable fin flatness. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31482 |
| Date | 21 March 2003 |
| Creators | Kanlayasiri, Kannachai |
| Contributors | Paul, Brian K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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