- Author
- Nguyen, T. | Hubbard, J. B. | Pommersheim, J. M.
- Title
- Models for the Degradation of Organic Protective Coatings on Steel.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD Bucknell Univ., Lewisburg, PA
- Book or Conf
- Durability of Building Materials and Components 6. Volume 2. Durability, Repair, Design. Proceedings of the Sixth (6th) International Conference. Chapter 5.4. October 26-29, 1993, E & FN Spon, New York, Omiya, Japan, Nagataki, S.; Nireki, T.; Tomosawa, F., Editors, 1070-1079 p., 1993
- Keywords
- steels | coatings | degradation | blisters | diffusion
- Identifiers
- blistering; cation; defects; electrolyte
- Abstract
- Conceptual and mathematical models for the degradation of a protective coating on a steel substrate exposed to an electrolytic environment are described. This is part of our continuing effort to develop credible approaches to service life prediction. The models were developed based on the concept that corrosive species attack the metal following their transport through imperfect regions in the coatings; the attack then causes separation of the coating from the substrate near the corroded sites. The imperfect regions are assumed to be defects in an impermeable film. Models for the separation (delamination and blistering) resulting from corrosion reactions are based on the diffusion of cations along the coating/steel interface from the defects to cathodic sites under the coatings. The mathematical models are solved to prediction fluxes and concentration profiles along the interface and within blisters. Model variables include blister size, distance between blister and defect, ion diffusivity, and potential gradients. Experimental results agree well with theoretical predictions.