Porous ceramic fiber glass matrix composites for solid oxide fuel cell seals

Porous ceramic fiber glass matrix composites with porosities of 19–24% were prepared with mixtures of a glass and short alumino-silicate ceramic fibers for the sealing of solid oxide fuel cells. The sealing performance was evaluated by measuring leak rates at the seal operation temperature of 650 °C and by investigating adherence at seal–metal interfaces after the seal test. Composite seals prepared with 55 vol% glass in the mixture showed a leak rate of ∼105 sccm/cm and did not adhere to the metal tube. Leak rate could be reduced to ∼0.003 sccm/cm when using composite seals prepared with 65 vol% glass. The maximum size of the pores present at the seal interface was estimated from the standard leak rate by assuming a single leak hole.