Towards the Validation of a Phase Field Model for Ni Coarsening in Solid Oxide Cells

Ni coarsening in the Ni/yttria-stabilized zirconia (YSZ) fuel electrode of solid oxide cells (SOCs) is a major cause of long-term performance degradation. Phase-field modeling is a powerful tool for studying Ni coarsening in the complex 3D structures of SOC fuel electrodes. In this work, we present a study aimed at validating a phase-field model, comparing simulation results with time-dependent ex-situ tomographic data. Three equilibrium Ni/YSZ contact angles are examined: 97 degrees, 120 degrees, and 150 degrees. Simulated microstructures are characterized through quantities such as the Ni mean radius, triple-phase boundaries, and interface shape distribution. The phase-field model reproduces the improved pore connectivity in the first stage of Ni coarsening observed in the tomography data. This model also indicates that the contact angle plays a key role in the microstructural evolution during Ni coarsening, and the best match to the experiment was obtained with the equilibrium contact angle of 120 degrees, close to a measured value in literature. Finally, the limitations of the model are discussed. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.