The Effect of High-Temperature Dual Reducing/Oxidizing Gas Conditions on Silver- Based Filler Metal Compositions
One of the critical issues in designing and fabricating planar solid oxide fuel cell stacks is the ability to hermetically seal adjacent metal and ceramic components. Depending on the specific design, the seal will be exposed simultaneously to an oxidizing atmosphere on one side and a reducing atmosphere on the other at an operating temperature of 500 – 850°C. In addition it will experience numerous thermal cycles, yet must continue to exhibit hermeticity, mechanical ruggedness, and chemical stability over the lifetime of the device; typically on the order of several thousand hours. We are currently developing a new brazing technique that can be conducted directly in air without the use of fluxing agents to remove surface scale during joining. To date we have shown that several of the developmental silver-based filler metal compositions display good joint strength, excellent stability under high-temperature oxidizing conditions, and superior thermal cycling performance in comparison with glass-based seals. However, there are concerns about exposing silver alloys to a high-temperature, hydrogen-rich environment, particularly with respect to potential embrittlement under these conditions. In this paper, we discuss results obtained from an initial series of experiments designed to characterize the effect of simultaneous hydrogen/air exposure on silver-based air brazes at high temperature.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1060144
- Report Number(s):
- PNNL-SA-43104; AA6010000
- Resource Relation:
- Conference: Joining of Advanced and Specialty Materials VII: Proceedings from Materials Solutions October 18–20, 2004, Columbus, Ohio, 18-26
- Country of Publication:
- United States
- Language:
- English
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