The Influence of Glass Flake and Micaceous Iron Oxide on Electrochemical Corrosion Performance of Waterborne Silicate Coatings in 3.5% NaCl Solution

Waterborne silicate composite coatings were prepared to replace existing solvent-based coatings for ships. A series of complex coatings were prepared by adding anticorrosive pigments to the silicate resin. Adhesion, pencil hardness, and impact resistance were investigated, and corrosion performance in 3.5% NaCl solution was measured by electrochemical impedance spectroscopy (EIS). The results show that adhesion and impact resistance are high, and that pencil hardness can reach 4H. The curing mechanism for the coatings were investigated by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The mechanism of curing reaction in the studied waterborne silicate paint was found to be different from that reported in the literature. When the coatings were immersed in 3.5% NaCl solution for 8 h, there is only one time constant in the Bode plot, and coating capacitance (Qc) gradually increases while coating resistance (Rc) gradually decreases. Glass flake composite coatings have better corrosion resistance by comprehensive comparison of Qc and Rc.