Galvanic Corrosion Fatigue Testing of 7075-T6Aluminum Bonded with Graphite-Epoxy Composite.

摘要

Galvanic corrosion effects were determined on 7075-T6 aluminum with attached, adhesively bonded sections of graphite-epoxy composite material. Fatigue tests were conducted on specimens exposed to a sulfur dioxide-salt spray environment in a chamber constructed on a Krouse direct-stress fatigue machine. S-N curves were developed under tension-tension conditions (R = 0.1) and with unprotected specimens, a 20 percent reduction in fatigue life was attributed to the contacting graphite-epoxy composite material. Protective coatings and nonconductive barriers to break the galvanic corrosion circuit were evaluated under the same corrosion fatigue (tension-tension) test conditions. Epoxy primer-polyurethane paint systems, polysulfide sealants and glass cloth barriers were used to measure their effectiveness in galvanic corrosion control. Metallograph and SEM (Scanning Electron Microscope) observations were made of corrosion sites and fatigue surfaces. (Author)