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Non-Osmotic Blister Growth Model in Coating Systems.

pdf icon Non-Osmotic Blister Growth Model in Coating Systems. (635 K)
Chuang, T. J.; Nguyen, T.

Damage and Failure of Interfaces (DFI-1), 1st International Conference. Proceedings. September 22-24, 1997, Vienna, Austria, A.A.Balkema Publishers, Brookfield, VT, Rossmamith, H., Editor(s), 203-209 pp, 1997.


coatings; blister growth


A blister growth model is proposed for a coating system consisted of a polymer film applied to a steel substrate exposed to salt solutions. The blister is considered to grow at a constant rate between the coating and the rigid steel substrate. The mechanism of the blister formation is based on corrosion-induced disbondment of the coating at the defect periphery coupled with the stress driven diffusive transport of liquid along the coating/substrate interface at the delamination front. The driving force leading to blister growth is the applied bending moment induced by the in-plane compressive stress of the swelling "buckled" film. By considering the coating as a semi-double cantilever beam loaded by a moment at the periphery, and a distributed load along the beam length due to mass transport, a fifth order ordinary differential equation is derived for the beam "deflection", and the solution is obtained which yields the functional relationship between the blister growth rate and applied bending moment. The predicted blister growth velocity compared favorably with experimental observations on a paint coated steel panel immersed in a 5% salt water solution.