Interface Reactions Responsible for Run-Out in Active Brazing: Part 1
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
The run-out phenomenon was observed in Ag-Cu-Zr active braze joints made between the alumina ceramic and Kovar™ base material. Run-out introduces a significant yield loss by generating functional and/or cosmetic defects in brazements. A prior study identified a correlation between run-out and the aluminum (Al) released by the reduction/oxidation and the latter’s reaction with the Kovar™ base material. A study was undertaken to understand the fundamental principles of run-out by examining the interface reaction between Ag-xAl filler metals (x=2, 5, and 10 wt.%) and Kovar™ base material. Sessile drop samples were fabricated using brazing temperatures of 965°C or 995°C and times of 5 min or 20 min. The correlation was made between the degree of wetting-and-spreading by the sessile drops and the run-out phenomenon. Wetting-and-spreading increased with Al content (x) of the Ag-xAl filler metal, but was largely insensitive to the brazing process parameters. The increased Al concentration resulted in higher Al contents of the (Fe, Ni, Co)xAly reaction layer. Run-out was predicted when the filler metal has a locally-elevated, Al content exceeding 2 – 5 wt.%. Lastly, several mitigation strategies were proposed, based upon these findings.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Security (NA-70)
- Contributing Organization:
- American Welding Society
- Grant/Contract Number:
- AC04-94AL85000; NA0003525
- OSTI ID:
- 1429670
- Report Number(s):
- SAND--2017-11635J; 658200
- Journal Information:
- Welding Journal, Journal Name: Welding Journal Journal Issue: 2 Vol. 97; ISSN 0043-2296
- Publisher:
- American Welding SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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