Friction properties of co-sputtered sulfide/DLC solid lubricating films

In recent years, diamond-like carbon (DLC) films are attracting attention as excellent tribomaterials due to their excellent characteristics such as a high hardness, a smooth surface, antiwear property, and lubrication characteristic, and they are applied in various fields. However, both the friction coefficient and endurance life of DLC films are not sufficient depending on the application environment. Therefore, in this study, with the aim of improving tribological characteristics, we fabricated WS2/DLC and MoS2/DLC films by co-sputtering under various conditions, using a multicathode sputtering system as well as graphite, WS2 and MoS2 as a target. Cross-sections of the films fabricated were observed by transmission electron microscopy. In addition, the composition and structure of the films were analyzed by Raman spectroscopy and Auger electron spectroscopy. With respect to the friction and wear characteristics of the films, measurement was performed using a ball-on-disk friction tester. As a result, we found that the films show a nanocomposite structure, a nanolayered structure or a random-layered structure depending on the deposition conditions. Regarding the wear characteristics, films having a nanocomposite structure or nanolayered structure show friction and wear characteristics superior to those of a DLC-only film.