Assessment of anti-corrosion coatings adhesion using terahertz time domain reflection spectroscopy

Corrosion is a significant economic problem, accounting for up to 5% of the Global GDP. New coatings are being developed to prevent corrosion, but they must bond well with the metal surface, have a minimal thickness, and not delaminate over time. Coating adhesion is crucial for the coating system to attain its design lifetime. Coatings applied following the manufacturer’s recommendations generally offer good adhesion to the substrate and can resist the permeation of corrosive agents. Coating adhesion depends on the coating property and substrate cleanliness, surface roughness, and any pre-treatments before coating application. The study evaluated the effects of surface roughness profile morphology and height on the pull-off adhesion strength value of the coating and its correlation with interfacial adhesion at the coating and substrate. The results show that delamination of coatings on steel used to protect the material from corrosion can be detected using terahertz reflection spectroscopy. The THz data agree well with standard industry pull-off testing. The study provides evidence that THz reflection spectroscopy can be used for non-destructive testing of anticorrosion coatings and the aging process.