REACTIVE AIR BRAZING OF LSCoF AND ALUMINA WITH Ag-V2O5 ALLOYS FOR SOFC APPLICATIONS
The feasibility of brazing LSCoF ceramic substrates with silver-vanadium pentoxide (Ag-V{sub 2}O{sub 5}) alloys for use in solid oxide fuel cell (SOFC) applications was studied. Preliminary testing was also performed on the Ag-V{sub 2}O{sub 5}/alumina (Al{sub 2}O{sub 3}) system in order to determine the feasibility of brazing LSCoF to Fecralloy{trademark} with an Ag-V{sub 2}O{sub 5} alloy since an Al{sub 2}O{sub 3} layer is formed on the Fecralloy surface prior to brazing. Sessile drop tests were performed using liquid Ag with 1 to 20 weight percent (wt%) V{sub 2}O{sub 5} additions at either 1000 or 1100 C. Similar to previous results for Ag-CuO alloys, additions of V{sub 2}O{sub 5} resulted in a decrease in the apparent contact angle and a transition from non-wetting to wetting behavior for both substrate materials. Mechanical test samples were fabricated by brazing using Ag with 1, 2 and 5 wt% V{sub 2}O{sub 5} additions. For the Ag-V{sub 2}O{sub 5}/LSCoF samples, the joint fracture strengths ranged from 10 to 30% of the monolithic LSCoF fracture strength ({sigma}{sub joint} = 26 {+-} 9 MPa versus {sigma}{sub LSCoF} = 151 {+-} 24 MPa). An SEM/EDS microstructural analysis of the brazed cross-sections indicated the formation of a vanadium rich reaction product at the braze/LSCoF interface. It is hypothesized that the reaction product provided improved chemical bonding at the interface that resulted in the modest joint strengths. In the the Ag-V{sub 2}O{sub 5}/Al{sub 2}O{sub 3} system, although the contact angles were less than 90{sup o}, all of the brazed Al{sub 2}O{sub 3} samples failed to bond during brazing or fractured during sample preparation. These poor adhesion results indicate potential problems with the Fecralloy{trademark}/Ag-V{sub 2}O{sub 5}/LSCoF system.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1048628
- Report Number(s):
- PNNL-SA-45286; AA6010000; TRN: US201216%%1055
- Resource Relation:
- Conference: Proceedings of the 29th International Conference on Advanced Ceramics and Composites, January 23-28, 2005, Cocoa Beach, Florida. Ceramic Engineering and Science Proceedings, 26(3):341-348
- Country of Publication:
- United States
- Language:
- English
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