Researchers found that the damage morphology of thick multilayer protective systems under impact loading shows specific patterns.

The research proves that the forces applied to the layers result in specific deformations and damage. Source: Julia Jones - stock.adobbe.com

The response of organic coatings to mechanical impact is crucial to their corrosion protection performance, particularly under offshore conditions. The paper categorizes and discusses four different types of response during the high-energy (3 to 20 J) impact of a falling ball-shaped weight on 14 multilayer organic offshore coating systems. The response types include plastic deformation, brittle (compressive) crushing, radial crack formation, and lateral delamination. Threshold and transition conditions are analyzed based on contact mechanics relationships.

For the first time, complete force-deflection curves for this type of coating are recorded with an instrumented impact tester. The curves feature four characteristic points, namely a first local force maximum (FFS), the respective deflection at this force level (δFS), a maximum force (Fmax), and the respective deflection at this maximum force (δmax). These characteristic parameters are discussed in terms of coating system composition. Empirical equations for these parameters as well as for the damage size are derived. The results offer opportunities to quantitatively rank organic coatings with respect to their impact resistance.

Source: Journal of Coatings Technology and Research, Volume 21, pages 857–878, (2024)