Material Degradation during Isothermal Aging and Thermal Cycling of Hybrid Mica Seal with Ag Interlayer under SOFC Exposure Conditions
Hybrid phlogopite mica seals with silver interlayers were evaluated in terms of materials degradation in a combined isothermal ageing and thermal cycling test. The hybrid mica seal was composed of a phlogopite mica paper sandwiched between two Ag foils. The hybrid micas were first aged at 800oC for ~1,000 hrs in a moist, dilute hydrogen fuel (~2.7% H2/bal. Ar + ~3% H2O), followed by short-term thermal cycling between ~100oC and 800oC. The combined test was repeated for 3 times for a total of 4,000 hrs ageing at 800oC and 119 thermal cycles. The results of high temperature leak rate tests showed very good thermal stability and thermal cycle stability with 800oC leak rates of ~0.02-0.03 sccm/cm. A hybrid mica seal tested in a high water content fuel (30 v% H2O/70 v% H2) demonstrated similar leakage during isothermal ageing and subsequent thermal cycles. Post-mortem analyses showed no extensive reaction between Ag and phlogopite mica as well as no significant mica degradation. Simple calculations to estimate the effect of measured leakage on the open circuit voltage and the total fuel loss for various SOFC stack sizes suggest very small fuel losses for the current hybrid mica seals, indicating that they are good candidates for SOFC sealing applications. Corresponding author: Yeong-Shyung Chou Tel: 509-375-2527, Fax: 509-375-2186, E-mail: yeong-shyung.chou@pnl.gov
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 896330
- Report Number(s):
- PNNL-SA-47857; AA2530000; TRN: US200703%%672
- Journal Information:
- Journal of the Electrochemical Society, 153(8):A1591-A1598, Journal Name: Journal of the Electrochemical Society, 153(8):A1591-A1598
- Country of Publication:
- United States
- Language:
- English
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