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Fabrication, Thermophysical, And Mechanical Properties Of Cermet And Cercer Fuel Composites For Nuclear Thermal Propulsion, Neal D. Gaffin
Fabrication, Thermophysical, And Mechanical Properties Of Cermet And Cercer Fuel Composites For Nuclear Thermal Propulsion, Neal D. Gaffin
Doctoral Dissertations
Nuclear thermal propulsion (NTP) utilizes nuclear fission to double the efficiency of
in-space propulsion systems compared with traditional combustion rocket systems.
NTP systems are limited primarily by the fuel material choice, due to the extreme
conditions they will need to endure, including temperatures up to 3000 K, multiple
thermal cycles with rapid heating and cooling, exposure to hot flowing hydrogen,
large thermal gradients, and high neutron flux. Particle based fuels, namely ceramic-
metallic (cermet) and ceramic-ceramic (cercer) composites are both promising fuel
element material candidates for NTP. Given the high temperature nature, these
materials are difficult to fabricate and very …
Pinless Friction Stir Spot Welding Of Ti-6al-4v Alloy For Aerospace Application, Hyojin Park
Pinless Friction Stir Spot Welding Of Ti-6al-4v Alloy For Aerospace Application, Hyojin Park
Doctoral Dissertations
Friction Stir Spot Welding (FSSW) is a newly developed solid-state joining technique with considerable merits over conventional spot-welding techniques, such as relatively simple procedure and excellent welding properties. It has been successfully implemented for the joining of light-weight structural materials, such as Al- and Mg-based alloys, with superior weldability and reduction of the manufacturing costs and energy consumption. In addition, by removing the pin from the friction stir spot welding tool, the pinless FSSW (p-FSSW) has minimized the formation of welding defects such as keyhole and hooking, which resulted in further improvements in the mechanical properties of weldments. However, the …