The detrimental thermal stresses in planar SOFC stacks can be reduced
using sliding seals. In the proposal planar stack, the electrolyte fil
m 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 degre
es C. The coefficient of friction between Hastelloy X and YSZ increase
d 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 rin
gs under a stack pressure of 0.1kg cm(-2).