Waterborne corrosion-resistant hydrophobic alkyd resin composite coatings modified with fluorinated acrylate–siloxane and submicron-sheet zinc phosphate pigment

Waterborne polymeric coating for corrosion protection has been of particular interest both in academia and industrial circles for years because of its low cost and low-volatile organic compound (VOC) emissions. However, organic coating is permeable to water and oxygen resulting in the reduction of anticorrosion properties during coating application. In this study, waterborne corrosion-resistant hydrophobic-modified alkyd resin composite coatings using fluorinated acrylate–siloxane (FASAR) and submicron-sheet zinc phosphate (Zn₃(PO₄)₂) pigment were prepared. The results of hydrophobicity, thermal, and mechanical measurements indicated that the FASAR30/5%Zn₃(PO₄)₂ had excellent performance. More importantly, the EIS and potentiodynamic polarization tests revealed that the acquired films also exhibited high anticorrosion property for carbon steel. The corrosion current density (i_corr) was 7.20 × 10⁻⁷ A cm⁻², with an inhibition efficiency of 99.92%, and a corrosion rate of 8.37 × 10⁻³ mm per year. On the other hand, the impedance modulus (Z_f = 0.01 Hz) of FASAR30/5%Zn₃(PO₄)₂ still had 5.68 × 10⁴ Ω cm² after 14-day immersion in the 3.5 wt% NaCl solution.