|About this Abstract
||2021 TMS Annual Meeting & Exhibition
||Thermal Property Characterization, Modeling, and Theory in Extreme Environments
|| First-principles Modeling of High Temperature Irradiation Resistant Thermocouple (HTIR-TC) Performance and Oxidation
||Lan Li, Ember L. Sikorski, Richard S. Skifton, Brian J. Jaques
|On-Site Speaker (Planned)
||Ember L. Sikorski
Instrumentation is needed to characterize experiments in research reactors that can operate at over 1000˚C. To meet this need, Idaho National Laboratory has been developing High Temperature Irradiation Resistant Thermocouples (HTIR-TCs) composed of Mo and Nb thermoelements separated by Al2O3 insulation. Using Ab initio Molecular Dynamics and Boltzmann Transport Equations, we calculated the Seebeck emf, a thermoelectric property, to measure the materials’ voltage response to temperature change in HTIR-TCs. With this method, HTIR-TC performance were predicted with respect to temperature, transmutation, and oxidation. Accelerated by high temperature, oxygen could diffuse into the thermoelements from the insulation or the air or water present in the reactor. To better understand the possible causes of thermoelement oxidation, we investigated Mo-Al2O3 and Nb-Al2O3 interfaces and the Mo and Nb surfaces in the presence of O2 and H2O at high temperatures. Diffusion mechanisms and their effect on HTIR-TC performance were also investigated.