The Importance Of Galvanic Protection In Zinc-Rich Coatings

Abstract

This paper reviews different types of zinc-rich coatings and lists the advantages and disadvantages of organic and inorganic zinc-rich coatings. The general types and curing mechanisms of some recently developed self-cured inorganic zinc-rich coatings are also discussed. The major characteristic, which distinguishes a zinc-rich coating from ordinary zinc dust paint and other protective coatings, is illustrated.A review of various test procedures for determining the degree of galvanic protection and their shortcomings is made. At the present time, there is no single, simple method available that can be used to establish the cathodic properties of zinc-rich coatings. Although there is a relationship between the amount of zinc dust present in the dry film and the galvanic protection, the type of binder also plays an important role.This study shOWS that humidity chamber (Vshaped window) exposure and immersion in sodiumchloride solution are inexpensive methods for determining the galvanic property of a zinc-rich coating. The bare steel area of the panel can develop rust when a coating without galvanic protection is used in an immersion period of 2 hours. However, a coating with good galvanic action provides protection for a longer period of time.References and illustrations at end of paper.