As primary cause of a coating failure, surface preparation is a crucial, but often overlooked step of coating application. Coatings require a clean substrate to some degree and a surface profile to ensure maximum adhesion strength. But do all profiles of the same depth provide the same coating adhesion? The USACE Paint Technology Technical Center of Expertise examines the benefits of utilizing alternative blasting media that can provide advanced adhesion through the use of grit composed of variated material and size. Laboratory studies will be used to illustrate this technology on steel test panels coated with epoxy and vinyl resin military systems. Surface morphology and surface area calculations, and results from performance testing, including cyclic corrosion testing, will be presented and compared to conventional blasting material along with a cost savings assessment.
Corrosion is a universal challenge for metal structures. Metal, due to its natural strength, is a common choice for building materials yet sensitive to the environment it is placed in, requiring mitigating actions to ensure proper lifecycle. Coatings are utilized as the primary defense against corrosion; the type based on substrate material and environment. However, coatings are still susceptible to failure through defects or degradation. Conventional approaches to this problem involve formulating innovative coatings to provide higher levels of corrosion mitigation. However, there is significantly less focus on the most common cause of coating failures, poor surface preparation. Coating adhesion is dependent on a clean, sound surface and proper surface profile. The surface profile increases the surface area of the substrate, increasing the adhesion sites and performance. In all instances, the better the surface preparation, the longer the service life of the structure.
A coating adheres to a surface through the means of Van der Waals Interactions. These are random interactions between two atoms based on their polarization that can lead to adhesion between two surfaces. While this adhesion is temporary, it can have an unexpected magnitude of strength, where the force of the interactions is related to the surface properties.1 The force of the Van der Waals interactions is directly proportional to the force required to separate the two surfaces.1
