Research on enhancing the corrosion resistance of epoxy-modified Fe3O4 coating on steel in a 3.5% NaCl environment Pham Hong Thach1, 2*, Phu Phuoc Huy2, Pham Trung Kien2, Tran Van

This study aims to improve the corrosion resistance of steel in a 3.5% NaCl environment by developing epoxy coatings containing surface-modified Fe3O4 nanoparticles. Fe3O4 was synthesized via co-precipitation, functionalized with 3-aminopropyltriethoxysilane (APTES) to improve dispersion, and combined with triethanolamine (TEA) as a surfactant to stabilize morphology. Five coating systems, pure epoxy, epoxy–Fe3O4, epoxy–Fe3O4/TEA, epoxy–APTES–Fe3O4, and epoxy–APTES–Fe3O4/TEA, were prepared. The nanoparticle structure and morphology were analyzed using XRD, FT-IR, SEM and EDX, while corrosion resistance was evaluated via potentiodynamic polarization (PDP) và electrochemical impedance spectroscopy (EIS). Results showed that APTES functionalization improved nanoparticle dispersion and interfacial bonding, while TEA reduced particle size and prevented agglomeration. The epoxy–APTES–Fe3O4/TEA system exhibited the best corrosion protection. These findings highlight the potential of modified epoxy nanocomposite coatings for marine steel protection.