Bonded Compliant Seal (BCS)
One of the critical issues in designing and fabricating a high-performance, planar, solid oxide fuel cell (SOFC) stack is the development of the appropriate materials and techniques for hermetically sealing the metal and ceramic components.Description
Researchers at PNNL have developed a foil-based sealing approach that appears to offer good hermetic and mechanical integrity, while minimizing the generation of high stresses in either of the joint’s substrate materials. Based on the concept’s viability, demonstrated in prior experimental work, numerical analyses have been conducted to evaluate the behavior and benefits of the seal in a configuration prototypic of current SOFC stack designs.
The results of these tests indicated that the foil seal is able to accommodate a significant degree of thermal mismatch strain between the metallic support structure and the ceramic cell via elastic deformations of the foil and plasticity in the foil-to-cell braze layer. Consequently the cell stresses in this type of seal are predicted to be much lower than those in the glass-ceramic and brazed designs, which is expected to lead to improved stack reliability.
- Mechanically compliant (flexible, not rigid)—the non-rigid material will not build up stresses in components being joined together
- Materials selection is not limited on factors including oxidation issues, creep issues, and high-temperature strength
- Improved performance of the cell
- Mid- and high-temperature electrochemical applications such as solid oxide fuel cells, gas separation devices (e.g., hydrogen concentrators and air separation units), and sensors
- Applications/devices that require ceramic-to-metal seals or joints
|Title and Abstract||
Joint with application in electrochemical devices
A joint for use in electrochemical devices, such as solid oxide fuel cells (SOFCs), oxygen separators, and hydrogen separators, that will maintain a hermetic seal at operating temperatures of greater than 600.degree. C., despite repeated thermal cycling excess of 600.degree. C. in a hostile operating environment where one side of the joint is continuously exposed to an oxidizing atmosphere and the other side is continuously exposed to a wet reducing gas. The joint is formed of a metal part, a ceramic part, and a flexible gasket. The flexible gasket is metal, but is thinner and more flexible than the metal part. As the joint is heated and cooled, the flexible gasket is configured to flex in response to changes in the relative size of the metal part and the ceramic part brought about by differences in the coefficient of thermal expansion of the metal part and the ceramic part, such that substantially all of the tension created by the differences in the expansion and contraction of the ceramic and metal parts is absorbed and dissipated by flexing the flexible gasket.
|Pacific Northwest National Laboratory||09/14/2010
|Technology ID||Development Stage||Availability||Published||Last Updated|
|14163-E||Prototype - Reduced to practice||Available - Available for licensing in all fields||09/10/2010||09/10/2010|