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The role of surface chemical analysis in a study to select replacement processes for TCA vapor degreasingThe role of surface-sensitive chemical analysis (ESCA, AES, and SIMS) in a study to select a process to replace 1, 1, 1-trichloroethane (TCA) vapor degreasing as a steel and aluminum bonding surface preparation method is described. The effort was primarily concerned with spray-in-air cleaning processes involving aqueous alkaline and semi-aqueous cleaners and a contamination sensitive epoxy-to-metal bondline. While all five cleaners tested produced bonding strength results equal to or better than those produced by vapor degreasing, the aqueous alkaline cleaners yielded results which were superior to those produced by the semi-aqueous cleaners. The main reason for the enhanced performance appears to be a silicate layer left behind by the aqueous alkaline cleaners. The silicate layer increases the polarity of the surface and enhances epoxy-to-metal bonding. On the other hand, one of the semi-aqueous cleaners left a nonpolar carbonaceous residue which appeared to have a negative effect on epoxy-to-metal bonding. Differences in cleaning efficiency between cleaners/processes were also identified. These differences in surface chemistry, which were sufficient to affect bonding, were not detected by conventional chemical analysis techniques.
Document ID
19950025388
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Lesley, Michael W.
(Thiokol Corp. Brigham City, UT, United States)
Davis, Lawrence E.
(Physical Electronics Labs. Eden Prairie, MN., United States)
Moulder, John F.
(Physical Electronics Labs. Eden Prairie, MN., United States)
Carlson, Brad A.
(Physical Electronics Labs. Eden Prairie, MN., United States)
Date Acquired
September 6, 2013
Publication Date
March 1, 1995
Publication Information
Publication: NASA. Marshall Space Flight Center, Aerospace Environmental Technology Conference
Subject Category
Mechanical Engineering
Accession Number
95N31809
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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