WS₂ films exhibit excellent tribological properties in a vacuum, but they are prone to failure due to oxidation in air, which severely limits their application. Cu has great potential to improve the tribological properties of WS₂, similar to that of Au and Ag. Thus, to clarify the contribution of Cu to the tribological properties of WS₂ films and provide new insight for the development of new multi-environmentally adaptable films, this study deposited WS₂-Cu composite films under different sputtering powers of the Cu target by magnetron sputtering systems, and the Cu target was supplied by DC power. Then, the structure of films was analyzed by FESEM, EDS and XPS. The results show that Cu is difficult to uniformly dope on the WS₂ film at a high sputtering power of Cu target, showing possibly low solubility of Cu in WS₂ film. However, a uniform and dense WS₂-Cu composite film was deposited under the lower sputtering power of Cu target. Furthermore, the results of the nanoindentation test demonstrated that the WS₂-Cu composite films exhibited high hardness (6.6 GPa). Finally, the tribological properties of the WS₂-Cu films were examined, and their friction interface was characterized by SEM, EDS and TEM. The WS₂-Cu film demonstrated superior tribological behavior in air (the average friction coefficient is 0.09), based on a special sliding interface, low oxidation levels of WS₂ and Cu-rich transfer film. This study provides a new insight and a new method for improving the environmental adaptation ability of WS₂ film.

WS₂ coating, as a solid lubricating material, plays a significant role in the lubrication of rotating components in spacecraft. During the launch process, however, spacecraft are exposed to high-temperature and humid atmospheric environments, which can lead to oxidative failure in the coating, thereby limiting its engineering applications. By doping with B elements, B/WS₂ was successfully prepared as a composite coating. The results demonstrate that the fabricated coating exhibits excellent high-temperature tribological performance in atmospheric environments. The mechanism through which B doping improves the high-temperature friction and wear properties of the WS₂ composite coating was revealed through high-temperature friction and wear tests. With the incorporation of B elements, the average friction coefficient of the coating was 0.071, and the wear rate was 7.63 × 10⁻⁷ mm³·N⁻¹·m⁻¹, with the wear mechanisms identified as abrasive wear and spalling. Due to high-temperature oxidation, thermal decomposition effects, and the formation of WB₄ during sputtering, the wear resistance and anti-plastic deformation capability of the coating were further improved. Compared to room-temperature test conditions, the B/WS₂ composite coating at different high temperatures exhibited superior friction coefficients and wear rates. Notably, at 150 °C, the average friction coefficient was as low as 0.015, and the wear forms were abrasive wear and adhesive wear.

This study investigated the impact of deposition pressure on the microstructure and tribological properties of B/WS₂ composite coatings deposited via unbalanced magnetron sputtering. Deposition pressures of 0.6 Pa, 0.8 Pa, 1.0 Pa, 1.2 Pa, and 1.4 Pa were used during the deposition process. The microstructure and mechanical properties of the B/WS₂ composite coatings were characterized, and friction and wear experiments were conducted. The study found that the microhardness of the B/WS₂ composite coatings decreased as the deposition pressure increased. The highest hardness of the coating, reaching 8.1GPa, was observed at a deposition pressure of 0.6 Pa. This was due to the formation of Tungsten tetraborate (WB₄) during the deposition process, which had a high hardness and improved the mechanical properties of the coating. The wear life of the B/WS₂ composite coatings was at its best, reaching 9.9 × 10⁴ cycles, and the friction coefficient was at its lowest when the deposition pressure was 1.2 Pa. Selecting an appropriate deposition pressure can improve the tribological properties of B/WS₂ composite coatings. Doping Boron can improve the hardness and wear resistance of the composite coatings. Abrasive wear and spalling are the two main wear forms of B/WS₂ composite coatings.