Accession Number:

ADA164772

Title:

Accelerated Corrosion Testing of Graphite/Epoxy Composites and Aluminum Alloy Mechanically-Fastened Joints

Descriptive Note:

Final rept. 1 May 1980-20 Dec 1984

Corporate Author:

AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH

Report Date:

1985-06-20

Pagination or Media Count:

50.0

Abstract:

This program evaluates the effectiveness of a currently used finishing system to protect graphiteepoxy composites mechanically fastened to aluminum substructures with either titanium or A-286 CRES fasteners. Lap joint samples of laminated graphiteepoxy or - 45O29O4 or -45Os 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 graphiteepoxy 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.

Subject Categories:

  • Laminates and Composite Materials
  • Couplers, Fasteners and Joints

Distribution Statement:

APPROVED FOR PUBLIC RELEASE