Kinetics of Seawater Diffusion into an Anticorrosion Coating with Modified Carbon Nanomaterials

The influence of modified (oxidized and doped) carbon nanomaterials added to a PVC-based enamel on the kinetics of seawater diffusion into a protective coating has been studied. To this end, the feasibility of using diffuse reflectance infrared spectroscopy and open-circuit potential (OCP) noise measurements of a three-electrode cell for investigating water diffusion kinetics was examined. The applicability of these methods was validated by electrochemical impedance spectroscopy (EIS) measurements. OCP noise and trend line monitoring has potential for broad application due to its simplicity and low cost compared to EIS, as well as its capability for diagnostics of anticorrosion coatings at the earliest stages of water diffusion into the coating. Oxidized few-layer graphene nanoflakes exhibited outstanding barrier properties (low water capacity, low rate of water diffusion into the coating, the high coating resistance and low rate of coating resistance degradation) as components of anticorrosion coatings. This performance is attributed to a high density of oxygen-containing functional groups, which ensure homogeneous nanofiller dispersion and promote strong interfacial adhesion to the polymer matrix via hydrogen bonding.