Non-Osmotic Blister Growth Model in Coating Systems.
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.
Keywords:
coatings; blister growth
Abstract:
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899