عنوان مقاله [English]
Polymeric coatings protectec susbstrates against corrosion by forming a physical and electrical barrier between substrates and corrosive enviroments. The barrier properties of coatings strongly depends on the chemical and physical structure of binders, the shape, size and concentration of pigments; and pigments / binders interaction. Water plays an important role in corrosion of substrates and photochemical reactions of binders as well. Water could also cause loss of ahesion between coatings and substrates. Therefore, studying barrier property of coatings to water permeability may be used for the evaluation of performance of coatings. In this article, water permeability of the coatings, parameters describing water permeability and the relation between water permeability and coating composition are discussed.