Scratch behavior of multilayer polymeric coating systems

A three-dimensional finite element method modeling along with experimental study on multilayer acrylic coating systems on a hard and brittle substrate has been performed to understand their scratch-induced deformation and damage mechanisms. The experimental results show that, while all else kept the same, an increase in soft (i.e., low Young's modulus and low strength) base layer thickness or hard (i.e., high Young's modulus and high strength) top layer thickness improve the scratch resistance of brittle coating systems by delaying the onset of cracking. The onset of plowing is delayed with the increase in hard top layer thickness, whereas increase in soft base layer thickness results in an earlier onset of plowing. The numerical analysis of the stress and strain field explains the mechanics behind the observed scratch behavior in the multilayer coating systems. The study provides insights toward designing scratch-resistant multilayer coating systems.