The Investigation of a Biocide-Free Antifouling Coating on Naval Steels Under Both Simulated and Actual Seawater Conditions

This study developed a water-soluble antifouling coating to protect ship hulls against corrosion and fouling without the usage of a primer. The coating retains its adhesion to the steel substrate and reduces corrosion rates compared to those for uncoated specimens. The coating’s protective properties rely on the interaction of conductive polyaniline (PAni) nanorods, magnetite (Fe3O4) nanoparticles, and graphene oxide (GO) sheets modified with titanium dioxide (TiO2) nanoparticles. The PAni/Fe3O4 nanocomposite improves the antifouling layer’s out-of-plane conductivity, whereas GO increases its in-plane conductivity. The anisotropy in the conductivity distribution reduces the electrostatic attraction and limits primary bacterial and pathogen adsorption. TiO2 augments the conductivity of the PAni nanorods, enabling visible light to generate H2O2. The latter decomposes into H2O and O2, rendering the coating environmentally benign. The coating acts as an effective barrier with limited permeability to the steel surface, demonstrating outstanding durability for naval steel over extended periods.