Electrochemical Corrosion Behavior of HiPIMS‑Deposited Diamond‑Like Carbon (DLC) Coatings on AISI 52100 Steel in Synthetic Seawater

This manuscript evaluates the electrochemical corrosion resistance of diamond-like car-bon (DLC) coatings deposited via High-Power Impulse Magnetron Sputtering (HiPIMS) on AISI 52100 steel in synthetic seawater. While AISI 52100 steel is valued for its hardness, it is highly susceptible to localized and uniform corrosion in chloride-rich marine environ-ments. In this study, samples were characterized using Raman spectroscopy to analyze sp2/sp3 bonding, and their corrosion behavior was assessed through potentiodynamic po-larization, linear polarization resistance (LPR), and electrochemical impedance spectros-copy (EIS) over 24 hours of immersion. Results demonstrated that the DLC coatings signif-icantly enhanced electrochemical stability, shifting corrosion potentials toward more no-ble values and reducing corrosion current densities by several orders of magnitude com-pared to the uncoated substrate. EIS data revealed high polarization resistance and effec-tive barrier properties, despite a calculated total porosity of 3.06% resulting from intrinsic micro-defects. Although localized subsurface degradation and minor flaking were ob-served at defect sites, the HiPIMS-deposited DLC coatings effectively mitigated the corro-sive impact of synthetic seawater, providing a robust protective barrier for high-precision steel components.