A Comparative Study on the Electrochemical Properties of Water-Based Inorganic Zinc-Rich Coatings and Solvent-Based Epoxy Zinc-Rich Coatings

In marine and industrial environments, zinc-rich coatings based on cathodic protection properties are among the most widely used and recommended coatings for the protection of metal surfaces from corrosion. Nevertheless, there is a paucity of research examining the electrochemical characteristics of water-based inorganic zinc-rich coatings and solvent-based epoxy zinc-rich coatings. Therefore, this paper presents a comparative analysis of the electrochemical properties of a solvent-based epoxy zinc-rich coating and a water-based inorganic zinc-rich coating. The objective of this study was to systematically examine the anticorrosion properties of bothcoatings using the following methods: open circuit potential (OCP), low-frequency impedance modulus, and electrochemical impedance spectroscopy (EIS) curve. The experimental results demonstrated that both coatings offered effective cathodic protection to the metal substrate. Comparatively, the water-based inorganic zinc-rich coating displayed a superior cathodic protection effect, which is attributed to its loose and porous structure. The distribution of zinc powder during the coating preparation enhanced the filling of internal voids within the coating system, promoting electrical connectivity between the zinc powder and the metal substrate, as well as among the zinc particles themselves. This interaction increased the utilization efficiency of zinc powder within the coating, thereby improving its cathodic protection capabilities. These findings contribute to the theoretical understanding of the protective mechanisms of zinc-rich coatings.