Effect of chemically-induced expansion on damage of solid oxide fuel cell

The influence of chemically-induced expansion on the fracture damage of a ceria based solid oxide fuel cell (SOFC) was investigated by using numerial stress analyses. The single cell examined in this study was composed of electrolyte [ (CeO₂) _0.8(SmO_1.5) _0.2], anode (Cermets of NiO-20 SDC), and cathode (La _0.6Sr_0.4Co_0.2Fe_0.8O₃), respectively. The finite element method was employed to calculate the residual stress, thermal stresses, and chemically-induced expansion stresses for the single cell. The residual and thermal stresses were calculated much smaller than the fracture strength of the individual components of the single cell. On the other hand, the chemically-induced expansion stresses were shown to remarkably increase for the temperature range greater than 973 K and accounted their magnitude for the primary part of the induced stress. It was shown from the stress analysis that the maximum stress induced in the single cell exceeded the fracture strength of the individual components at the onset of the fracture damage detect by acoustic emission method. The above-mentioned calculation results suggest that the chemically-induced expansion should be taken into account for the use of ceria based ceramics materials in SOFCs.