Thermal conductivity of Mo-reinforced ZrO 2 composites fabricated by spark plasma sintering for inert matrix fuels Qusai M. Mistarihi a , Vivek Raj b , Joon Hui Kim c , Ho Jin Ryu a, ⁎ a Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong, Daejeon 34141, Republic of Korea b Indian Institute of Technology-Kanpur, Kalyanpur, Kanpur, Uttar Pradesh 208016, India c Department of Material Science and Engineering, KAIST, 291 Daehak-ro, Yuseong, Daejeon 34141, Republic of Korea HIGHLIGHTS • Mo wire mesh-reinforced ZrO 2 compos- ites fabricated by spark plasma sintering. • Finite element analysis of the thermal conductivity agrees well with modeling. • Interconnected Mo wire mesh improves the thermal conductivity of ZrO 2 composites. GRAPHICAL ABSTRACT abstract article info Article history: Received 5 June 2017 Received in revised form 1 September 2017 Accepted 3 September 2017 Available online 06 September 2017 ZrO 2 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 ZrO 2 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 ZrO 2 composites fabricated by spark plasma sintering at 1700°C in vacuum was investigated. It was found that structures with a higher degree of in- terconnectivity of the high thermal conductivity reinforcements were more effective in increasing the thermal conductivity of ZrO 2 composites. The Mo wire mesh-ZrO 2 composites had a higher thermal conductivity than did the Mo powder-ZrO 2 composites, owing to the interconnected structure of the former. The thermal conduc- tivities of the Mo-ZrO 2 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 conduc- tivity of Mo-reinforced ZrO 2 composites. © 2017 Elsevier Ltd. All rights reserved. Keywords: ZrO 2 Mo wire mesh Mo powder Thermal conductivity Finite element analysis Analytical modeling 1. Introduction Uranium dioxide (UO 2 ) is the most commonly used nuclear fuel for commercial nuclear power plants, because of its high melting point (2800°C) and its compatibility with water (the main coolant in nuclear power reactors) and because there is extensive experience with using Materials and Design 134 (2017) 476–485 ⁎ Corresponding author. E-mail address: hojinryu@kaist.ac.kr (H.J. Ryu). http://dx.doi.org/10.1016/j.matdes.2017.09.004 0264-1275/© 2017 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes