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Title: Interface Reactions Responsible for Run-Out in Active Brazing: Part 1

Abstract

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.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Security (NA-70)
Contributing Org.:
American Welding Society
OSTI Identifier:
1429670
Report Number(s):
SAND-2017-11635J
Journal ID: ISSN 0043-2296; 658200
Grant/Contract Number:  
AC04-94AL85000; NA0003525
Resource Type:
Accepted Manuscript
Journal Name:
Welding Journal
Additional Journal Information:
Journal Volume: 97; Journal Issue: 2; Journal ID: ISSN 0043-2296
Publisher:
American Welding Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Vianco, Paul T., Walker, Charles A., De Smet, Dennis J., Kilgo, Alice C., McKenzie, Bonnie M., and Grant, Richard L. Interface Reactions Responsible for Run-Out in Active Brazing: Part 1. United States: N. p., 2018. Web. doi:10.29391/2018.97.004.
Vianco, Paul T., Walker, Charles A., De Smet, Dennis J., Kilgo, Alice C., McKenzie, Bonnie M., & Grant, Richard L. Interface Reactions Responsible for Run-Out in Active Brazing: Part 1. United States. doi:10.29391/2018.97.004.
Vianco, Paul T., Walker, Charles A., De Smet, Dennis J., Kilgo, Alice C., McKenzie, Bonnie M., and Grant, Richard L. Thu . "Interface Reactions Responsible for Run-Out in Active Brazing: Part 1". United States. doi:10.29391/2018.97.004. https://www.osti.gov/servlets/purl/1429670.
@article{osti_1429670,
title = {Interface Reactions Responsible for Run-Out in Active Brazing: Part 1},
author = {Vianco, Paul T. and Walker, Charles A. and De Smet, Dennis J. and Kilgo, Alice C. and McKenzie, Bonnie M. and Grant, Richard L.},
abstractNote = {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.},
doi = {10.29391/2018.97.004},
journal = {Welding Journal},
number = 2,
volume = 97,
place = {United States},
year = {2018},
month = {2}
}

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