Tribological Performance of Tetrahedral Amorphous Carbon (ta-C) Coatings on Plasma-Nitrided X153CrMoV12 Cold Work Tool Steel

Diamond-like carbon (DLC) coatings, specifically tetrahedral amorphous carbon (ta-C), provide hard, low-friction carbon films suitable for tribological applications in demanding industrial environments. In this study, we investigated diamond-like carbon (ta-C) deposited by PVD arc technology (Ionbond Tetrabond), its quality, and applicability on tool steels, X153CrMoV12. Three different surface treatments were applied: plasma nitriding (535 °C, 9 h), DLC coating, and duplex plasma nitriding combined with DLC coating. The DLCs were characterized using characterization techniques, such as Raman, XPS, SEM, and XRD. XPS analysis reveals sp3 fractions of approximately 60% (DLC-only coating) and 62% (duplex nitrided + DLC coating) which confirm the high quality of the deposited ta-C films. Wear tests were conducted under loads of 10 N and 20 N, with a speed of 0.04 m/s and a distance of 100 m. Low coating thickness (~400 nm) limited load-carrying capacity, leading to premature wear and substrate exposure, as well as increased friction under continuous loads. Compared to non-coated samples, ta-C coating exhibits improved adhesion resistance to delamination if deposited on a nitrided substrate. The duplex nitrided and DLC-coated configuration achieved the most significant reduction in wear track width of up to 78% compared to the uncoated baseline, establishing it as the optimal surface treatment strategy for industrial cold-forming applications. The coefficient of friction (CoF) for the duplex-treated sample remained the lowest throughout testing, confirming its superior tribological performance. This research paves the way to improvements in tool steels and coating technology of diamond-like carbon.