Accession Number:

ADP006820

Title:

Environmental Degradation of High Temperature Composites

Descriptive Note:

Corporate Author:

NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA

Report Date:

1992-04-01

Pagination or Media Count:

13.0

Abstract:

A study was performed to assess the effect of galvanic corrosion phenomena on the strength of graphitebismaleimideBMI composites. The results indicate that degradation occurred in BMI composites galvanically coupled to aluminum alloys. The mechanism responsible for the degradation involves hydroxyl ion generation in the cathodic reaction. Optical and electron microscopy of the surface of coupled specimens showed a great deal of cracking and deterioration of the resin. This phenomenon is thought to be associated with stresses in the resin imposed by thermal or chemical processes. These cracks may be an indication that the mechanism of degradation is not simply the hydroxyl attack on the resin but a combination of chemical and mechanical attack. Composite- aluminum material couples were exposed to salt waterfuel solutions and to salt spray environment and then composite properties were determined. Conventional protection schemes were evaluated. The results indicated that the performance retention was test specific and that bearing tests were most sensitive to the galvanically induced degradation. Significant bearing strength loss was found when the protection schemes failed. In addition, a systematic study of the electrochemical conditions which were most important in control of the degradation rates was performed.

Subject Categories:

  • Aircraft
  • Coatings, Colorants and Finishes
  • Laminates and Composite Materials
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE