Local heterogeneities can have significant effects on the performance of anti-corrosion coatings. Even small features can act as initiation points for damage and result in corrosion of the substrate material. Analysis methods with high spatial resolution and the ability to collect information relevant to crosslinking and degradation behavior of these coatings are therefore highly relevant. In this work, we demonstrate the utility of nanomechanical AFM measurements and nano-FTIR in investigating the nanoscale mechanical and chemical properties of two polyester coil coating clearcoats before and after weathering. On the nanoscale, weathering led to a stiffer and less deformable coating with less variation in the nanomechanical properties. Chemical degradation was quantified using changes in band ratios in the IR-spectra. Macro and nano-scale measurements showed similar trends with the latter measurements showing larger heterogeneity. Our results demonstrate the usefulness of the described analysis techniques and will pave the way for future studies of local properties in other coating systems and formulations. © 2024 The Authors

FTIR-ATR (Focal Plane Array) FPA spectroscopic imaging was used to obtain depth resolved information about degradation of a polyester melamine coating by performing measurements on drilled conical holes. The results of the FTIR-FPA imaging show that combined effect of UV and moisture resulted in larger degradation effects in the outermost parts of the coatings but loss of melamine functionality was detected to the depth of approximately 8–10 μm after 2163 h weathering in QUVA accelerated test and after 4 years exposure in a marine environment. Longer periods of accelerated weathering, up to 4000 h, resulted in degradation through the whole coating outer layer.