Preparation of epoxy/ZrO2 composite coating on the Q235 surface by electrostatic spraying and its corrosion resistance in 3.5% NaCl solution

Abstract

The epoxy coating containing ZrO₂ nanoparticles modified with 3-aminopropyltriethoxysilane (APTES) was prepared by electrostatic spraying on the surface of Q235 mild steel. The effect of the concentration of APTES-modified ZrO₂ nanoparticles on the corrosion resistance of epoxy coating was characterized and tested by FTIR spectroscopy, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results show that nano ZrO₂ was successfully modified by a silane coupling agent. By adding an appropriate amount of APTES to modify nano ZrO₂ in epoxy coating could significantly improve the corrosion resistance of the Q235 surface. When the mass fraction of nano ZrO₂ is 2%, the composite coating shows the highest impedance value of about 1.0 × 10⁵ Ω cm² to achieve the best corrosion resistance.