• Co-addition of CeO2 and benzotriazole significantly enhances the corrosion resistance of epoxy resin coatings on Q235 carbon steel.
• The optimal coating composition (0.3% CeO2 and 20% BTA) provides superior long-term corrosion protection due to synergistic barrier and chemical effects.
• Electrochemical tests (polarization and impedance) confirm improved corrosion performance, while XRD analysis reveals the formation of protective corrosion products.
• The study offers a practical approach to developing high-performance epoxy coatings for marine and industrial applications.