Hybrid phlogopite mica seals with silver interlayers were evaluated in long term isothermal ageing tests in a dual environment consisting of dilute hydrogen vs. air at 800 degrees C. High-temperature leak tests with helium showed very stable leakage of 0.01-0.02 sccm/cm for 28366 hrs under a low applied compressive stress of 82 kPa (12 psi). Post-mortem SEM and EDS analyses of the mica showed minimum degradation in terms of changes in microstructure and chemical composition, although there appeared to be some Ag migration and segregation at interstices between mica flakes. Fluorine was also found to be released from mica. Overall, the low, constant leakage through the hybrid mica/Ag seals clearly demonstrated a very promising candidate for SOFC sealing.
Revised: July 16, 2010 |
Published: June 15, 2009
Citation
Chou Y.S., and J.W. Stevenson. 2009.Long-term ageing and materials degradation of hybrid mica compressive seals for solid oxide fuel cells.Journal of Power Sources 191, no. 2:384-389.PNNL-SA-64433.