Understanding Corrosion Protection Requirements for Adhesive Bond Primers
Technical Report,01 Mar 2011,31 Mar 2016
Naval Air Warfare Center, Aircraft Division Patuxent River United States
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Based on tests conducted in this project, hexavalent chromium corrosion inhibitors in adhesive bond primers were found to have less significance than expected for adhesive bondline environmental durability. Cytec BR 6747-1 chromated and BR 6747-1NC noninhibited were the basis primers for testing and analysis. Additional tests using 3M EW-5000 chromated, 3M EW-5000ET non-chromate inhibitor, and EW-5000-NC experimental, noninhibited primers served to validate results. Test configurations included aluminum wedge crack extension and double cantilever beam specimens bonded with epoxy film adhesives, which were exposed to long-term marine atmospheric and accelerated indoor corrosion environments. Samples also underwent mechanical and electrochemical stress cycles and were subsequently post-analyzed for failure mode, moisture ingress, and corrosion. Many of the traditional and novel tests conducted during the effort did not show significant differences between chromated and nonchromated bond primers in adhesive bondlines. Though certain rigorous tests used to qualify materials and processes for bonded joints did show chromated primers provide a positive contribution to environmental durability, even these tests revealed surface preparation is the dominant factor for aluminum bonded joint environmental durability performance.
- Adhesives, Seals and Binders