Effect of Dielectric Barrier Discharge plasma on Surface Properties for Medium Carbon Steel

Abstract

This study investigates the effect of dielectric barrier discharge (DBD) plasma treatment on the surface modification of medium carbon steel (CK45). The process was carried out in ambient air at a voltage of 15 kV and frequency of 20 kHz for exposure times of 0–12 min. The influence of plasma duration on microstructure, surface hardness, wear, and corrosion resistance was systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical Tafel polarization. Results revealed the formation of a dense nitride–oxide layer mainly composed of Fe₄N and Fe₃N with minor Fe–O–N phases. The Vickers hardness increased from 240 Hv (untreated) to 330 Hv after 12 min of treatment, representing a 37.5 % improvement. The corrosion current density decreased from 2.4×10^-3 A/cm² to 5.3×10^-5 A/cm², while wear rate was significantly reduced. These enhancements are attributed to grain refinement, lattice strain, and the formation of a compact nitride barrier layer that suppresses anodic dissolution and surface wear. The results demonstrate that air-based DBD plasma is an eco-friendly, low-temperature, and energy-efficient alternative to conventional nitriding processes for improving the tribo-corrosion performance of medium carbon steels.