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.
