Materials and Approaches for Improved Stress Corrosion Inhibitive Coatings.
Abstract
The purpose of this program was to develop new materials and approaches for improved stress corrosion inhibitive coatings for critical stress corrosion prones components of current and future aircraft and missile systems. Currently used coatings function primarily by limiting the access of the corrosive environment to the metal. If such coatings are breached by scratches or abrasions, all protection is lost. An improved coating should be self-healing, i.e., give protection when scratched. To achieve such self-healing characteristics, a multiple-layer coating process has been used. In this new coating, the key element has been the development of a tenacious, adherent anodized layer that is a far more effective base layer than either the currently used MIL-A-8625C sulfuric acid anodizing procedure or the conversion coating process, MIL-C-5541B. This new coating layer is produced by an anodization carried out in low melting point eutectic nitrate mixture. The resulting anodized layer provides a sealable base for the incorporation of stress corrosion inhibiting agents as well as acting as an extremely effective layer for the subsequent application of polymeric-elastomeric paints. Screening tests of a large number of candidate corrosion inhibitors has shown that zinc dichromate is by far the most effective inhibitor for the suppression of stress corrosion. Direct comparison tests of MIL-Spec painted and scratched samples have demonstrated that the new coating procedure is more than four times more effective in inhibiting stress corrosion than previous MIL-Spec processes. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1973
- Accession Number
- AD0913433
Entities
People
- D. R. Cogley
- F. H. Cocks
- G. L. Holleck
- I. W. Frutkoff