Improvement of the Tribological Properties of DLC/oxynitriding Duplex-treated AISI H13 Alloy Steel

In this study, diamond-like carbon (DLC) films were prepared by DC-pulsed plasma CVD after the oxynitride treatment of AISI H13 tool steel. In order to investigate the tribological properties of DLC films, a Raman spectroscopy analysis, wear test, adhesion and roughness tests were performed. The main parameters of the DC-pulsed plasma CVD process includes various pretreatment times of argon plasma (15, 30, 45 and 60 min). Experimental results showed that an oxynitride layer and the DLC films could be completely obtained after DLC/oxynitriding duplex treatment. The duplex coating layers had optimal adhesion (critical load reached to 10.65 N) and wear properties after DC-pulsed plasma was CVD treated via a low pulse voltage (-1.5 kV), pretreatment times of the argon plasma were 15 min and the substrate temperature was kept at 40 C. Meanwhile, the optimal DLC/oxynitriding duplex treated specimens possessed the lowest wear volume (2.25 x 10(-3) mm(3)) and a lower friction coefficient (0.06).