Study of polymer coating delamination kinetics on zinc modified with zinc oxide of different morphologies

Abstract

Industrially prepared materials surfaces often possess complex morphologies and topographies. Using rough model interfaces, the effect of the surface morphology on the delamination of a polymer coating from zinc surfaces is investigated in this work. Zinc oxide particles of different shapes with characteristic dimensions $1 µm were deposited on zinc surfaces to serve as model corrosion products with well-defined morphologies. Surfaces with spherical, rod-shaped, and twin-plateshaped zinc oxide particles were prepared and characterized by scanning electron microscopy (SEM) as well as X-ray diffraction (XRD). The surfaces were subsequently coated with poly(vinyl butyral) (PVB) as a model for a weakly bound polymer coating. Scanning Kelvin probe (SKP) measurements were carried out in humid air to study the delamination kinetics. Results were compared to PVB on zinc. While delamination is fastest on zinc without zinc oxide particles, the delamination rate on the particle-covered surfaces strongly depends on the particle morphology. Delamination rate increases in the order sphere < rod < twin-plate, with differences by one order of magnitude between fastest and slowest. The differences in delamination rate can be understood based on the surface energies of the terminating surfaces of the particles, and the resulting differences in stability under conditions of zinc oxide dissolution.

Pretreatment with a β-Cyclodextrin-Corrosion Inhibitor Complex Stops an Initiated Corrosion Process on Zinc

“…The β-CD­[MBT] complex does in addition contribute to the formation of the observed compact morphology with spherical particles (Figure c). The model polymer coating PVB used here was found to delaminate slower from zinc surfaces covered with zinc oxide in a spherical morphology, compared to other particle shapes . The delamination rate difference was a factor of 10 for systems with comparable chemical composition .…”

“…The model polymer coating PVB used here was found to delaminate slower from zinc surfaces covered with zinc oxide in a spherical morphology, compared to other particle shapes. 52 The delamination rate difference was a factor of 10 for systems with comparable chemical composition. 52 The differences in the delamination rate observed in this work may therefore be caused by the differences in morphology between the different surface studies.…”

New experimental approach for intelligent screening of buried metal/oxide/polymer interfaces via local electrochemistry: Example of undamaged model epoxy-coated Zn alloys

“…In order to understand the underpaint reactivity, the use of a model polymer seems to be a promising approach [42]. In the literature, several weakly adherent coatings, like polyvinyl butyral (PVB) or polyvinyl alcohol (PVA), were used in SKP studies of underpaint reactivity [43,44]. However, they do not sustain long term immersion because of their high solubility in water and weak adhesion to metallic substrates [45].…”

Cathodic delamination kinetics of thin polystyrene model coatings bound to zinc via organosilanes

“…All other chemicals were used as received. Zinc substrates (15 mm × 15 mm) were initially mechanically ground with SiC paper up to 4000 grit, followed by polishing with silicon paste of 1 m to have a smooth surface, in order to exclude effects of morphology, as discussed elsewhere . After polishing, the substrates were first thoroughly washed with deionized water followed by cleaning with ethanol in an ultrasonic bath and dried under a dry stream of nitrogen.…”