Behavior of High Temperature SOFC Materials Subjected to Thermal Cycles

Abstract

In order to evaluate the thermal stress of high temperature SOFC materials, four different square bars of materials were examined under four different thermal cycles. Materials composed of a Ni-YSZ anode in H2 and 5%H2-N2, a YSZ electrolyte, and a (La,Sr)(Cr,Co)O3 interconnect were unaffected by the thermal cycles. However, a Ni-YSZ anode in N2 purge gas and a (La,Sr)MnO3+d cathode in air were affected by the thermal cycles strongly. Thus, by using 5%H2-N2, the anode can evade thermal cycle damage. The shrinkage characteristic of two cathode materials in air and N2 atmospheres were also evaluated. A reduction of thermal cycle induced shrinkage is made possible by a mixture of La0.6Sr0.4MnO3 and stabilized zirconia materials, and when the atmosphere of the temperature decrease phase of the thermal cycle is nitrogen, the behavior becomes independent of the atmosphere for the temperature increase portion of the cycle.