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Failure of a Waterborne Primer Applied to Zinc Coated Steel
Author(s) -
Adhami Siavash,
Abel MarieLaure,
Lowe Chris,
Watts John F.
Publication year - 2012
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.4837
Subject(s) - durability , coating , primer (cosmetics) , zinc , materials science , corrosion , composite material , salt spray test , adhesion , passivation , chemistry , chemical engineering , metallurgy , layer (electronics) , organic chemistry , engineering
The durability of a high‐performance coating system based on a polyester top coat and a water‐based primer system has been studied by exposure of coated panels to salt spray and 100% RH. The humidity exposure is less deleterious than the salt spray with a higher concentration of an adhesion promoter further enhancing durability in each case. XPS analysis establishes that in both cases failure occurs as a result of a weak boundary layer of zinc oxide corrosion product. Further testing of these pre‐exposed panels using a wet adhesion test and a mechanical pull‐off test confirms the superior performance of the formulation with a higher level of adhesion promoter in both tests. The locus of failure is generally in the organic phase, although those specimens at the lower end of the performance spectrum show a significant amount of failure at or close to the coating/substrate interface. For samples pre‐exposed to the salt spray, the presence of chloride ions at the failed interface indicates that such a treatment may have a deleterious effect on subsequent performance. Copyright © 2012 John Wiley & Sons, Ltd.