Efficiency Analysis of Nanostructured Coatings in Protecting Marine Structures from Moisture and Extreme Salinity

Abstract

Marine structures are exposed to a highly aggressive environment characterized by continuous moisture, dissolved oxygen, chloride ions, cyclic wetting and drying, hydrostatic pressure, ultraviolet radiation, and mechanical damage. These conditions accelerate the corrosion of steel reinforcement, carbon-steel components, marine pipelines, offshore platforms, and port infrastructure. Nanostructured coatings introduce a multiscale protection mechanism based on reduced permeability, increased diffusion-path tortuosity, improved hydrophobicity, enhanced interfacial adhesion, electrical passivation, and, in selected systems, autonomous self-healing.Graphene, graphene oxide, silica nanoparticles, alumina, layered double hydroxides, nanoclays, zinc nanoparticles, and functionalized carbon nanotubes are among the principal nanofillers used in marine protective coatings. This paper develops a coupled mathematical and physical framework for evaluating nanostructured marine coatings. The framework integrates Fickian moisture transport, chlorideion migration, oxygen diffusion, electrochemical kinetics, coating capacitance, coating resistance, interfacial charge transfer, adhesion degradation, and crack-assisted transport.The theoretical analysis demonstrates that the optimum coating is not necessarily the system containing the highest nanoparticle concentration. Superior performance is obtained when the nanofiller is uniformly dispersed, chemically compatible with the polymer matrix, mechanically stable, electrically compatible with the substrate, and capable of creating a continuous tortuous diffusion path without generating agglomerates or microvoids. Nanocomposite coatings should therefore be considered coupled barrier–interface–electrochemical systems rather than simple waterproofing layers .