Effect of B Element Doping on High-Temperature Tribological Properties of WS2-Based Composite Coatings

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.