Vacuum Current-Carrying Tribological Behavior of NbSe₂ Coatings on Textured Surfaces

With the development of equipment and the continuous improvement of service requirements, the service life and other properties of space conductive lubrication materials have been shown to be significantly inadequate. At present, most of the studies on current-carrying friction and wear have been carried out in the atmospheric environment. However, in the vacuum environment, the friction and wear of metal materials or two-dimensional layered materials are very different from those in the atmosphere. In this paper, according to the special vacuum current carrying service requirements of the sliding electric contact parts of spacecraft, the possibility of NbSe₂ coating sprayed on the textured surface of copper substrate as a new conductive lubrication material was explored and studied by using the established vacuum current carrying friction test platform. Through a series of literature investigation, the stripe and mesh texture morphology were selected as the substrate for preparing the coating. The tribological properties and influence laws of NbSe₂ coating sprayed with strip texture and mesh texture were studied under different texture densities. The vacuum current carrying tribological properties and influence law of spray NbSe₂ coating with different texture morphology and different texture density were studied. The tribological and electrical contact behavior of textured surface sprayed niobium selenide coating under vacuum current carrying condition was investigated compared to active electric gold-plated coating. We hope to find a coating that maintains a low coefficient of friction and a stable current transmission in the harsh space environment while trying to replicate the actual conditions as much as possible. The results showed that the mesh texture was better than the strip texture coating effect, and with the increase of the texture density, the wear resistance of NbSe₂ coating was improved. The NbSe₂ coating sprayed on the surface with mesh texture with 200 µm micron texture spacing showed the best tribological performance in vacuum. The large density mesh texture stored the lubricant more effectively, so that the lubricant was continuously added to the sliding contact surface, forming a thin and uniform boundary lubrication film, which can not only play the role of effective lubrication, but also realize the efficient transmission of current by using the copper substrate groove edge and convex NbSe₂ thin layer structure. Compared to the gold coating, the NbSe₂ coating sprayed on the textualized surface exhibited better tribological and electrical contact properties under the condition of vacuum current-carrying friction. The friction coefficient decreased from 0.25 to 0.05. Although the contact voltage increased slightly at the same level, the electric noise fluctuation was significantly improved from 0.05 V to 0.02 V. This new material showed great advantages and application potential.