ABSTRACT
The protective properties are very dependent on adhesion and barrier properties, that are discussed in this chapter. The role of adhesion is to create the necessary conditions so that corrosion protection mechanisms can work. A coating cannot passivate the metal surface or create a path of extremely high electrical resistance at the metal surface unless it is in intimate contact— at the atomic level— with the surface. The importance of surface roughness on coating adhesion is well documented through both practical experience and laboratory investigations. Two aspects of adhesion are important: the initial strength of the coating– substrate bond and what happens to this bond as the coating ages. The most important corrosion protection mechanism of organic coatings is to prevent the formation of a water phase at the metal surface. The coating must be a barrier to ions in order to be able to provide durable protection.
