Temperature-dependent residual stresses in plasma sprayed electrolyte thin-film on the cathode substrate of a solid oxide fuel cell

This paper reports a measurement of residual stresses at different temperatures in plasma sprayed electrolyte thin-film on the cathode substrate of a solid oxide fuel cell. The study is carried out on a sample with bi-layer structure consisting of a thin-film of 8 mol% yttria-stabilized zirconia (8YSZ) and a Ca-doped LaMnO3 cathode substrate fabricated by Siemens' plasma spray technology. The lattice deformation is directly measured by the high-temperature X-ray diffractometry, from which the state and level of the residual stresses in the YSZ layer are further evaluated using the sin2ψ-methodology. The results reveal that the stresses in the electrolyte film are compressive in nature and remain essentially unchanged from room temperature to 600 °C. Above 600 °C, the compressive stresses monotonically decrease with the temperature as the lattice relaxation prevails. At 1000 °C, the electrolyte layer is still under compression, implying good bonding and very likely low interfacial contact resistance within the structure.