Imide/Graphite Composite Degradation Mechanism
Abstract
This report presents the results of the Phase I research undertaken by Foster-Miller, Inc. to establish at the molecular level, the mechanism of degradation of composites employing bismaleimide (BMI) resins when in contact with a corroding metal in an electrolytic saltwater solution. It also discusses Foster-Miller's approach to reducing this degradation by modifying the resin with hydroxyl scavengers. Our results indicated that samples which were modified with hydroxyl scavengers corroded at a rate greater than or equal to that of unmodified BMI control samples. Optical and SEM microscopy of corroded samples revealed that the main mechanism of corrosion was stress corrosion cracking. Microcracks first initiated in the surface resin, then propagated along the fiber-matrix interface beneath the resin surface, resulting in the peeling and flaking of large fragments of undegraded resin. In an effort to retard this mechanism, a sample containing epoxy-coated fibers was fabricated. It was postulated that the epoxy coating which is resistant to hydroxyl attack, might prevent the microcracks from propagating along the fiber matrix interface, thus preventing flaking of the resin. While the preliminary effort using epoxy coatings did not succeed in reducing corrosion, other polymeric coatings may be helpful in attaining this objective.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1995
- Accession Number
- ADA367009
Entities
People
- Doug Wilson
- J. Gassner
- M. Druy
- M. Groleau
- R. Kovar