Glass and glass-derivative seals for use in energy-efficient fuel cells and lamps
For solid oxide fuel cells (SOFC), a series of 18 sealing glasses have been prepared and characterized. From the whole design space, several glasses were ''downselected'' and studied in detail to describe their behaviors in simulated fuel cell environments. One of the glasses was found to outperform all others, including the well-known G18 sealant developed at Pacific Northwest National Laboratory. The new glass composition showed lower bulk electrical conductivity, excellent sealing and wetting behavior when sealing under applied load, and qualitatively superior performance when exposed to wet hydrogen for 800 hours. Traditional melting was used to prepare all of the glasses that were studied in detail. The sol-gel approach was used to synthesize several compositions, but it was found that the glasses crystallized very rapidly during heating, precluding sealing. The glass characterization included measurements of the viscosity and thermal expansion of the glasses, as well as the thermal expansion of the partly crystalline glass ceramics. In addition, the wetting and sintering behavior of all glasses has been measured, as well as the crystallization behavior. The time and temperature at which crystalline phases form from the glasses has been determined for all of the glasses. Each glass ceramic contains at least two crystalline phases, and most of the crystalline phases have been positively identified. The body of fundamental data provides a platform for future developments for high temperature sealants, and the newly-developed glass compositions appear promising for large-scale testing. The second component of the work, focused on seals for higher-temperature discharge lighting, has focused on determining the phase relations in the yttria-alumina-silica system at various silica levels. Functional testing of one of the candidate sealants demonstrated that it performs well in current HID lighting applications. Further testing is required to evaluate its performance in next-generation lamps that operate at higher temperatures, but the baseline phase equilibria and crystallization behavior has been established for additional development. Again, traditional melting and sol-gel synthesis have been employed, and the sol-gel method was successful for preparing new phases that were discovered during the work. Four new phases have been identified and synthesized in pure form, from which full structure solutions were obtained as well as the anisotropic thermal expansion for each phase.
- Research Organization:
- Alfred University
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-03NT41957
- OSTI ID:
- 887322
- Country of Publication:
- United States
- Language:
- English
Similar Records
Behavior of Aging, Micro-Void, and Self-Healing of Glass/Ceramic Materials and Its Effect on Mechanical Properties
Sintering behavior of lanthanide-containing glass-ceramic sealants for solid oxide fuel cells