Enhanced Tribocorrosion and Corrosion Resistance of R4 Grade Mooring Chain Steel Through Hybrid Ceramic Coatings

Abstract

This study investigates the microstructure, corrosion resistance, and tribocorrosion properties of a hybrid ceramic layer applied to R4-grade mooring chain steel. The coatings were produced using a two-step process: boriding followed by applying a titanium carbon-nitride (TiCN) layer via the Physical Vapor Deposition (PVD) process. X-ray diffraction (XRD) tests verified the creation of FeB, Fe2B, and TiCN phases. The borided layer provided a gradient-hardened structure, improving load-bearing capacity, while the TiCN film enhanced surface hardness. The electrochemical tests demonstrated that the hybrid ceramic coating considerably enhanced corrosion resistance compared to untreated and borided samples. Tribocorrosion tests revealed that the hybrid ceramic layer exhibited superior wear resistance, with a lower coefficient of friction and reduced wear rates. These findings indicate that the hybrid ceramic coating system can significantly enhance electrochemical and tribocorrosion resistance in seawater, extending the service life of R4 steel.