Evaluation of protective coatings for offshore applications. Corrosion and tribocorrosion behavior in synthetic seawater

Coatings have been widely used in the corrosion protection of metallic materials in marine environments. In this work, the corrosion and tribocorrosion behavior of three potential coatings employed in offshore applications has been evaluated. The coatings studied were a Thermally Sprayed Carbide coating with an organic sealant (C1), a Thermally Sprayed Aluminum with an organic sealant (C2), and an epoxydic organic coating reinforced with ceramic platelets (C3). Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization techniques have been employed to assess the corrosion performance of the coatings in synthetic seawater. Furthermore, unidirectional ball-on-disc tribocorrosion tests were performed to study the response of the coatings subjected to simultaneous action of wear and corrosion. The coatings were found to provide to the steel substrate with enhanced corrosion resistance, both in absence and during wear process, and to improve in the tribological properties with lower coefficients of friction in seawater. The coating less affected by sliding in terms of corrosion resistance was C2 coating, which also showed the lowest coefficient of friction.