Kim, Jun Woo Bae, Kiho Kim, Hyun Joong Son, Ji-won Kim, Namkeun Stenfelt, Stefan Prinz, Fritz B. Shim, Joon Hyung 2024-01-19T22:30:20Z 2024-01-19T22:30:20Z 2021-09-03 2018-07-05 0925-8388 https://pubs.kist.re.kr/handle/201004/121161 Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500-900 degrees C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol% YSZ appears primarily at 800 degrees C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation. (C) 2018 Elsevier B.V. All rights reserved. English ELSEVIER SCIENCE SA FOCUSED ION-BEAM NICKEL REDUCTION BEHAVIOR MICROSTRUCTURE PERFORMANCE HYDROCARBON CATHODE RECONSTRUCTION AGGLOMERATION Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells Article 10.1016/j.jallcom.2018.04.176 1 JOURNAL OF ALLOYS AND COMPOUNDS, v.752, pp.148 - 154 JOURNAL OF ALLOYS AND COMPOUNDS 752 148 154 scie scopus 000432672300019 2-s2.0-85045713450 Chemistry, Physical Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Chemistry Materials Science Metallurgy & Metallurgical Engineering Article FOCUSED ION-BEAM NICKEL REDUCTION BEHAVIOR MICROSTRUCTURE PERFORMANCE HYDROCARBON CATHODE RECONSTRUCTION AGGLOMERATION NiO-YSZ anode functional layer 3D reconstruction Focused ion beam-scanning electron microscope Finite element analysis Thermal stress