Development and performance evaluation of reduced graphene oxide/nitrides reinforced epoxy coatings for marine steel structures

The enhancement of durability in steel structures subjected to aggressive marine conditions presents a significant challenge in the realm of sustainable civil infrastructure. This study presents the uniform anchoring of functionalized nickel and manganese nitrides (Ni 3 N 2 and Mn 3 N 2 ) nanoparticles onto reduced graphene oxide (rGO) nanosheets, which were subsequently incorporated into an epoxy matrix to create a high-performance nanocomposite coating. The EP/rGO/API–Ni 3 N 2 /Mn 3 N 2 coating demonstrated enhanced anticorrosion efficiency and mechanical strength. Electrochemical impedance spectroscopy demonstrated a remarkably high coating resistance of 7.89 × 10 12 Ω.cm 2 and a charge transfer resistance of 7.50 × 10 12 Ω.cm 2 . Additionally, scanning electrochemical microscopy showed a notable decrease in corrosion current to 2.0 nA upon 720 h of exposure, while the pristine epoxy showed a higher current of 20 nA. The nanocomposite exhibited adhesion strength of 19.5 MPa and retained hardness levels from 1401 MPa to 1381 MPa following extended exposure, suggesting robust interfacial bonding between the rGO-functionalized nitrides and the epoxy matrix. The coating demonstrated improved hydrophobicity, achieving a contact angle of 155°, thereby offering an additional barrier to moisture ingress. The findings indicate that the EP/rGO/API–Ni 3 N 2 /Mn 3 N 2 nanocomposite coating provides enhanced corrosion resistance, mechanical integrity, and surface protection, positioning it as a viable option for prolonging the service life of steel components in marine and coastal civil engineering applications.