Influence of Zinc Phosphate Content on the Properties of Epoxy Resin-Siloxane Coating

Sodium phosphate,zinc sulfate,γ-aminopropyltriethoxysilane (KH-550) and epoxy resin (E51) were used as main raw materials to synthesize zinc phosphate by precipitation method.The epoxy resin-siloxane coatings containing different concentrations of zinc phosphate were prepared.The prepared coatings were characterized by Fourier transform infrared spectroscopy,scanning electron microscopy and X-ray diffraction.The corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS).The results show that epoxy resin was grafted by KH-550 successfully.The zinc phosphate powder was irregular in structure and mainly composed of Zn₃(PO₄)₂·4H₂O.When the amount of zinc phosphate added into the coating was controlled around 2.5%(mass fraction),the coating had high impedance and good corrosion resistance.