Nitrogen-doped DLC (diamond-like carbon) coatings were produced on 316L nitrided austenitic steel in direct current and pulsed glow discharge conditions. The chemical composition, surface topography, hardness and corrosion resistance of the obtained carbon coatings were examined. The coatings varied in surface morphology, roughness and hardness. Direct current glow discharge made it possible to produce a coating characterized by lower hardness, greater thickness and higher nitrogen content. The coating featured improved corrosion resistance and adhesion compared to coatings produced in the pulsed process.

The low adherence of diamond-like carbon (DLC) films on titanium (Ti) alloys can be improved by using interlayer coatings. In this study, DLC (a-C:H) films were deposited using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD), and a TiCN interlayer was applied between the extra low interstitial (ELI) grade of Ti-6Al-4V alloy and a-C:H film. The characteristics of the a-C:H-coated Ti-6Al-4V ELI alloy were investigated using field emission scanning electron microscopy, Vickers hardness, and scratch and wear tests. The DLC (a-C:H) films deposited by rf-PECVD had a thickness of 1.7 µm, and the TiCN interlayer had a thickness of 1.1 µm. Vickers hardness of the DLC (a-C:H) films were increased as a result of the influence of the TiCN interlayer. The resulting friction coefficient of the a-C:H-coated Ti-6Al-4V with the TiCN interlayer had an extremely low value of 0.07.