Accelerated Corrosion Testing of Graphite/Epoxy Composites and Aluminum Alloy Mechanically-Fastened Joints
Abstract
This program evaluates the effectiveness of a currently used finishing system to protect graphite/epoxy composites mechanically fastened to aluminum substructures with either titanium or A-286 CRES fasteners. Lap joint samples of laminated graphite/epoxy (+ or - 45/O2/9O)4/+ or -45/O)s and aluminum alloy plates (2124-T851) were fabricated using either titanium (NAS1154V4) or A- 286 CRES (MS 21140) fasteners. The unprotected baseline samples were fabricated by installing the fasteners in the uncoated graphite/epoxy aluminum alloy plates. The protected samples were exposed to humidity and salt fog for twelve weeks, tested in fatigue and exposed to the corrosive environment for twelve more weeks. The extent of corrosion was evaluated by both visual and microscopic examination. The unprotected samples experienced severe galvanic corrosion of the aluminum plate. The accelerated testing of the protected samples indicated the following problems: (1) If the area where the composite butts together in the lap joint was not properly sealed galvanic corrosion could occur in the aluminum. (2) If the composite was not painted on the edge, severe pitting of the primed aluminum alloy plate would occur on the edge of the aluminum plate. (3) The titanium fasteners performed better than the A-286 CRES fasteners.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 20, 1985
- Accession Number
- ADA164772
Entities
People
- Billy L. White
- James A. Snide
- S. D. Thompson
Organizations
- Wright Laboratory