Electrochemical properties and corrosion protection of zinc coatings in corrosive media

摘要

Solvent based zinc rich paints (ZRP) are well known as efficient organic coatings to protect metallic materials from corrosion [1]. Zinc pigment is cemented with an organic binder which is epoxy type and zinc represents 90wt.% of the formulation. Such paints can be considered as porous coating due to this metallic content and they have been studied for many years. The protection of steel by epoxy based zinc-rich paint is based on the general principle of cathodic protection by metallic zinc particles in contact with ferrous substrate. The positive effects of epoxy based zinc-rich in paint and on metal substrate towards corrosion resistance of paints have drawn much attention since late 1950s[2]. Several studies have been carried out in order to elucidate the influence of the zinc content on the electrochemical properties of these paints. Paint with zinc content higher than 60% by weigh is recommended to achieve good protection [3]. A great deal of effort has also been dedicated to review the worked related to contamination at the metal/paint interface before 1999. The influence of chlorides, sulfates and nitrates at steel/paint surface on the underfilm corrosion was also investigated.