The corrosion behavior of zinc-rich coatings on metallic substrates

 
Zinc-rich coatings (ZRC) have been widely used to protect steel from corrosion in various fields such as construction, automobile and electrical equipment. Corrosion protection is provided by both cathodic and barrier mechanisms. For adequate protection, both mechanisms should function at different stages of the coatings' lifespan. The quantity of zinc must be kept at about 90% by weight to ensure effective cathodic protection. Considering the high concentration, such high content causes a decrease in mechanical properties. The morphology (size and shape) of zinc particles has a significant role for balanced protection. In this article, various amounts (90, 70, 50, 30, and 10 % by weight in dry film) of zinc-containing systems were prepared by using zinc particles of sub-millimeter size and shape (flake and sphere). The prepared coatings are examined in terms of mechanical properties (adhesion and pendulum hardness), Neutral Salt Spray (NSS) test and Electrochemical Impedance Spectroscopy (EIS) in order to realize the anticorrosive behavior of the flake- and the spherical-shaped zinc particles