Frictional forces in an SOFC stack with sliding seals

The detrimental thermal stresses in planar SOFC stacks can be reduced using sliding seals. In the proposal planar stack, the electrolyte film is sandwiched by YSZ support rings to release the thermal stresses. In order to estimate the strength of the support ring, the frictional forces between heat resistant alloy and YSZ were measured at 900 degrees C. The coefficient of friction between Hastelloy X and YSZ increased when they were measured after 144h heating. However, the coefficient of friction between HA-214 and YSZ did not increase. The measurement and a calculation of the stresses in the support rings led the result that a thickness of 0.6mm was necessary for 200mm diameter support rings under a stack pressure of 0.1kg cm(-2).