Compliant alkali silicate sealing glass for solid oxide fuel cell applications: thermal cycle stability and chemical compatibility
An alkali silicate glass (SCN-1) is currently being evaluated as a candidate sealing glass for solid oxide fuel (SOFC) applications. The glass containing ~17 mole% alkalis (K2O and Na2O) remains vitreous and compliant during SOFC operation, unlike conventional SOFC sealing glasses, which experience substantial devitrification after the sealing process. The non-crystallizing compliant sealing glass has lower glass transition and softening temperatures since the microstructure remains glassy without significant crystallite formation, and hence can relieve or reduce residual stresses and also has the potential for crack healing. Sealing approaches based on compliant glass will also need to satisfy all the mechanical, thermal, chemical, physical, and electrical requirements for SOFC applications, not only in bulk properties but also at sealing interfaces. In this first of a series of papers we will report the thermal cycle stability of the glass when sealed between two SOFC components, i.e., a NiO/YSZ anode supported YSZ bilayer and a coated ferritic stainless steel interconnect material. High temperature leak rates were monitored versus thermal cycles between 700-850oC using back pressures ranging from 0.2 psi to 1.0 psi. Isothermal stability was also evaluated in a dual environment consisting of flowing dilute H2 fuel versus ambient air. In addition, chemical compatibility at the alumina and YSZ interfaces was examined with scanning electron microscopy and energy dispersive spectroscopy. The results shed new light on the topic of SOFC glass seal development.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1008212
- Report Number(s):
- PNNL-SA-76697; JPSODZ; AA2530000; TRN: US201106%%328
- Journal Information:
- Journal of Power Sources, 196(5):2709-2716, Vol. 196, Issue 5; ISSN 0378-7753
- Country of Publication:
- United States
- Language:
- English
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Compliant alkali silicate sealing glass for solid oxide fuel cell applications: the effect of protective alumina coating on electrical stability in dual environment
Compliant alkali silicate sealing glass for solid oxide fuel cell applications: the effect of protective YSZ coating on electrical stability in dual environment