Coatings update: A review of literature on adhesion

A typical coated system comprises a substrate to which a coating has been applied. The coating in turn usually consists of several layers. Failure of the system may result either cohesively or adhesively. Cohesive failure may cause the substrate itself to separate and thus the system has been injured. Although cohesive failure of the substrate is usually not a problem with metal, it may well be a problem with concrete. And, indeed, it may be facilitated if the coating adheres so strongly that forces at the coating‐concrete interface set up stresses within the concrete which cause it to disbond cohesively. Of course cohesive failure may occur within the coating itself or, if the layers of the coating are sufficiently distinct, within any one layer of the coating system.