ABSTRACT
Duplex coatings are now used extensively in various industries and constructions. Primarily, zinc has been used in duplex coatings, with great success. Zinc coatings are applied for their sacrificial protection of steel and low self-corrosion rate. Zinc-based duplex coating systems are extensively used in several industries, such as automotive, offshore wind energy, maritime, architecture, and infrastructure. Zinc-based duplex coatings protect the steel by a combination of two mechanisms. Obviously, the zinc provides cathodic protection of steel exposed at small damages in the coating. The other protection mechanism is that the paint film displaces water from the zinc surface, passivating the zinc. Electrogalvanized and hot-dip galvanized zinc coatings are often phosphated before the organic coating is applied, primarily to increase the adhesion of the organic coating to the zinc. Thermally sprayed aluminum (TSA) has a long history as a durable and protective metal coating.
