Abstract
In this study, DLC films were coated on oxynitriding-treated Vanadis 10 tool steel using the DC-pulsed plasma CVD technique. The experimental parameters included different duty cycles (9, 13, 17, and 21 %) with asymmetric bipolar-pulsed voltages of –3 kV, a gas flow of CH₄ maintained at 15 sccm, and a deposition time of 90 min. Meanwhile, the properties of DLC films were measured by Raman spectroscopy, Rockwell indentation, wear tests, FT-IR, corrosion tests, water contact angle tests, and four-point probes analysis. The experimental results showed that the optimum properties of DLC films occurred at a duty cycle of 17 %. It had the lowest wear volume loss for loads 2 N and 5 N were 3.49 × 10^–3 mm³ and 4.08 × 10^{–3 3} respectively. Moreover, the optimal DLC films possessed the lowest corrosion current (I_corr = 7.91 × 10^–5 A•cm^–2) and highest polarization resistance (R_p = 1185.21 O•cm²) in 3.5 wt.% NaCl solutions. The FT-IR spectrum analysis also found that the characteristic peaks of DLC films were generated at positions of 2852 and 2921 cm^–1, and the water contact angle tests showed that the DLC films had great hydrophobicity (78.33°). Consequently, the results confirmed that the duplex surface treatment effectively improved the coating properties of Vanadis 10 tool steel.

Key words
diamond-like carbon (DLC), oxynitriding, Vanadis 10 tool steel, DC-pulsed plasma-enhanced CVD, wear, corrosion, water contact angle

Full text (1176 KB)