New Technology Bonding Corrosion Protection and Durability

Four ply laminates of 2024-T3 and 7075-T6 bare and clad aluminum alloys, simulating the body skins of commercial aircraft, were used to study the effects of variation in aluminum alloy, surface preparation, primer and adhesive on bondline corrosion. Bolts and rivets were installed and typical aircraft finishes were applied on the specimens.

The specimens were exposed for 6 months, with and without stress, to a 5% neutral salt spray. Residual bond strength and corrosion damage were determined after exposure.

The test results indicate that overall bond durability provided by improved surface preparation (phosphoric acid anodize) and new epoxy adhesive systems was much superior to old technology adhesive bonding. The high level of bond durability demonstrated by the test results indicates that there is no evidence of bondline corrosion in any of the 36 specimens tested for each bonded assembly.