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.
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