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| Home > Publications database > Microstructural Evolution of Atmospheric Plasma Sprayed Manganese Cobalt Iron Oxide Protection Layers for Solid Oxide Fuel Cells |
| Conference Presentation (After Call) | FZJ-2017-02383 |
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2017
Abstract: In sold oxide fuel cells (SOFCs), chromium containing steels are widely used as interconnect material. On the one hand they fulfill the component’s demands, but on the other hand chromium species that evaporate at the high SOFCs working temperatures lead to a strong degradation of commonly used cathode materials. This chromium poisoning can be minimized by inserting a chromium protection layer between interconnect and cathode. Atmospheric plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective coatings have proven their effectiveness in reducing degradation rates within operated stacks in Jülich. Previous studies revealed phase and microstructural changes of these layers during annealing in air but couldn’t explain the underlying mechanisms, which are crucial for long term predictions. This study investigates long term annealed samples and will concentrate on the microstructural and phase changes, enabling a lifetime prediction of APS-MCF coatings. A self-healing of microcracks, which are present in as-sprayed coatings, is observed after annealing at 500°C in air. Diffraction patterns of the initial and annealed state reveal a phase change linked to the annealing process, explaining the healing effect by a volume expansion connected to an oxygen uptake. Visualization of the elemental distribution shows a demixing of cobalt and manganese after annealing at 700°C that is described by a simple model. Combining these results with those obtained from long term operated stacks can allow lifetime predictions of such protection layers.
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