Thermal conductivity of Mo-reinforced ZrO2 composites fabricated by spark plasma sintering for inert matrix fuels

Abstract

ZrO2 is one of the candidate materials for the matrix of inert matrix fuels because of its excellent chemical stability and irradiation resistance. In this paper, the low thermal conductivity of ZrO2 was increased by the addition of Mo reinforcements in order to improve its performance and therefore increase the safety of nuclear reactors. The effect of interfacial thermal resistance and reinforcement structure in terms of its size, shape, and orientation on the thermal conductivity of Mo powder- and Mo wire mesh-reinforced ZrO2 composites fabricated by spark plasma sintering at 1700°C in vacuum was investigated. It was found that structures with a higher degree of interconnectivity of the high thermal conductivity reinforcements were more effective in increasing the thermal conductivity of ZrO2 composites. The Mo wire mesh-ZrO2 composites had a higher thermal conductivity than did the Mo powder-ZrO2 composites, owing to the interconnected structure of the former. The thermal conductivities of the Mo-ZrO2 composites were also analyzed by the finite element analysis and using analytical models of the composites with the dispersed reinforcing particles and the interconnected reinforcement structures. A good agreement was found between the theoretically predicted and experimentally measured thermal conductivity of Mo-reinforced ZrO2 composites.