Tribological performance of WC/C-based DLC coatings under high temperature in dry and humid conditions

Wear-resistant diamond-like carbon (DLC) films are widely used in industrial, biomedical, and automotive applications. However, their tribological performance across different environmental conditions, particularly during transitions between humid and dry environments, remains poorly understood. This study examines the tribological performance of WC/C-based DLC coatings under varying loads, temperatures, and environmental conditions. The results indicate that wear remained consistent at room temperature and 100 °C but increased with higher loads and temperatures. Elevated temperatures, particularly in dry conditions, were associated with greater disorder and partial graphitization of the coating, as revealed by Raman spectroscopy. The lower friction and wear observed in humid environment were connected to the presence of oxygen that assisted in preserving the structure of the coating. Indeed, the tests conducted in dry oxygen atmosphere confirmed lower friction and prolonged lifetime of the coating. The coating's performance in humid and dry environments highlights the importance of considering environmental factors in real-world applications.