Corrosion behavior analysis of high-corrosion-resistant Zn-flake coatings

Abstract

The corrosion behavior of a Zn-flake coating—consisting of a Zn-flake topcoat and a high-corrosion-resistant Zn-based base layer—was comprehensively evaluated in comparison with electro-galvanized (EG), hot-dip galvanized (GI), bare steel, and STS 304 specimens. Potentiostatic electrochemical tests revealed that the Zn-flake coating exhibited lower and more stable current densities than EG and GI, indicating a pronounced barrier effect associated with its lamellar structure. Immersion tests (up to 40 days) and cyclic corrosion testing (CCT) further demonstrated superior medium- to long-term corrosion resistance, as evidenced by delayed onset of white and red rust formation and reduced coating degradation. Cross-sectional and EDS analyses also confirmed the structural stability of the coating layers and the suppression of corrosion propagation. These findings suggest that the Zn-flake coating provides an effective approach for enhancing long-term corrosion performance.