Effects of Aqueous Silicone-Acrylate Emulsions on the Corrosion Resistance of Silicate Zinc-Rich Coatings

The effect of water-based silicone-acrylic emulsion on the corrosion resistance of silicate zinc-rich coatings was studied. Neutral salt spray test was used to compare the corrosion resistance of the coating with different amounts of emulsion. With the aid of scanning electron microscopy and X-ray diffraction spectroscopy, the corrosion products of metallic zinc in the coating and their effects on the performance of the coating were studied. Through electrochemical impedance spectroscopy, the changes of coating resistance and capacitance during the corrosion process were studied, and the corrosion resistance mechanism of the coating was discussed. The results show that the corrosion products of zinc in the coating mainly include ZnO, Zn(OH)₂, Zn₅(OH)₈Cl₂·H₂O, etc. These products can make the coating denser and have a self-repairing effect on the coating. The coating with 0.5 g of water-based silicone-acrylic emulsion mixed with 30 g of base material had good adhesion to the substrate, and the anti-corrosion performance of the coating was significantly improved. After a 1 000 h neutral salt spray test and being immersed in 3.5% NaCl solution for 50 d, the coating had no obvious corrosion.