Sealing Effects of Silica Sol Modified Waterborne Acrylic Resin on Chromium Trivalent Passivation Film of Galvanized Steel

Abstract

In order to improve the corrosion resistance of the trivalent chromium passivation film on galvanized steel, the effects of silica sol modified waterborne acrylic resin on the passivation film were studied. The corrosion resistance and the thermal stability of the passivation film were measured by Tafel polarization curve, electrochemical impedance spectroscopy (EIS), salt water immersion test and neutral salt spray test (NSS), and the morphology and properties of the film were characterized by SEM, FT-IR and TGA. The results show that compared with the unmodified and unsealed passivation film on galvanized steel, silica sol modified sealant can significantly improve the resistance of the passivation film, effectively slow down the corrosion rate of the passivation film in 3.5%NaCl solution, and extend the enduring time under salt spray test; and the heat resistance of the passivation film can be improved remarkably by the introduction of silica sol.

Keywords

• passive film on galvanized steel
• waterborne acrylic resin
• silica sol modified
• corrosion resistance
• sealing