The generation of artificial microscopic defects in organic coatings by AFM scratching

Failure in the corrosion protection offered by organic coatings is most commonly instigated by defects traversing the film. However, the artificial defects used to assess corrosion resistance are ordinarily prepared using manual scribing techniques, producing inherently macroscopic scratches with variable dimensions. Here, we demonstrate an AFM scratching methodology for controlled introduction of reproducible microscale defects into a thin film of industrial epoxy phenolic can coating. Furthermore, local changes in topography and Volta potential are then monitored using Kelvin probe force microscopy (KPFM) following exposure to corrosive media (water or electrolyte).