The Relationship of Sulfuric-Chromic Acid (FPL) Etch Composition to the Surface Properties of 2024T-3 Aluminum Alloy

  • Alphonsus V. Pocius


The sulfuric-chromic acid (FPL) etch is one of the most commonly used surface preparations for adhesive bonding in the aircraft industry. We have determined various electrochemical parameters of 2024T-3 bare aluminum alloy in salt water and in the FPL etch solution as a function of predissolved 2024T-3 bare alloy in the etch bath. In addition, Auger Electron Spectroscopy and Scanning Transmission Electron Microscopy measurements were also performed on both 2024T-3 bare and clad alloy as a function of predissolved 2024T-3 bare alloy in the etch bath. The action of the predissolved alloy in the etch bath is to promote the growth of a thicker, and in some cases, a more porous oxide. Comparisons are made to other work in the literature and suggestions are given regarding the reasons for the increase in durability of adhesively bonded 2024T-3 alloy that was etched in an FPL etch bath containing predissolved alloy.


Auger Electron Spectroscopy Adhesive Bond Electrode Kinetic Forest Product Laboratory Bare Alloy 
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Copyright information

© Plenum Press, New York 1983

Authors and Affiliations

  • Alphonsus V. Pocius
    • 1
  1. 1.Adhesives, Coatings and Sealers Laboratory, 3MSt. PaulUSA

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