Abstract
One of the main challenges in solid oxide fuel cell (SOFC) is the redox problem of Ni-based anodes. Therefore, the redox tolerance of the anode should be improved to increase the service life of the system. Since the real SOFC anodes have a heterogeneous structure with different grain sizes, a micro-level modeling is necessary. Especially, the re-oxidation step which creates large amount of stress is critical during the redox cycles. Therefore, in this study, the effects of re-oxidation temperatures and exposure times on the oxidation rate and stresses developed are investigated on a synthetically generated porous anode functional layer microstructure. A mathematical model is developed to characterize the re-oxidation process and solved numerically. The results indicate that the re-oxidation strongly depends on the re-oxidation temperature and exposure time. The time required for the full oxidation is found to be 7458.55, 313.14, 200.8 and 33.78s at 800, 850, 900 and 950°C, respectively for the generated anode microstructure. In addition, the created stresses in the anode structure are well above the critical material limits.
Published Version
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