Solid Oxide Fuel Cell (SOFC) is a high-performance electrochemical device for energy conversion. A single cell is composed of 5 layers of different materials: anode support, anode functional layer, electrolyte, cathode functional layer and cathode. The mechanical integrity of the cell is a major issue during its life time, particularly for the electrolyte layer. Cell damage is mainly caused by the geometry of the system, the high operating temperature and the brittleness of the materials. Residual stresses are known to play a significant role in damage evolution, it is therefore important to determine them. For this purpose, residual stresses in an anode-supported planar SOFC were measured by X-ray diffraction using the Sin2Ψ method. Firstly, global stresses in each phase of each layer were measured using an X-ray goniometer at room temperature. This technique is based on measurements of the crystal lattice deformation. Secondly, local strain measurements were carried out on the grains of electrolyte layer by both X-ray synchrotron radiation and a new technique derived from EBSD pattern analysis. White beam micro-diffraction enables high accuracy measurement on a micrometer scale and can be used to determine the variation of deformation from grain to grain in the electrolyte. The spatial resolution of the EBSD based elastic strain measurement is much better, in the range of 20nm for ceramics materials. Stress variation within the grain can then be analysed. These two complementary techniques at different scales coupled with a fine characterization of the microstructure will contribute to a better understanding of the residual stresses in the electrolyte layer and thus to the damage mechanisms.
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