Towards the use of diamond-like carbon solid lubricant coatings in vacuum and space environments

Owing to the increasing demand in tribological performance for vacuum- and space-related applications, development of new solid lubricant coatings is necessary. Diamond-like carbon (DLC) coatings have been successfully used in many conventional mechanical applications to reduce both friction and wear. The potential use of these new solid lubricants under vacuum becomes then a critical question, which this article will attempt to address. DLC deposition, structure, and properties are first introduced to the reader. The exceptional tribological behaviour of DLC coatings is also discussed, in comparison with other tribological coatings. Attention is focused on the vacuum tribology of DLC films, pointing out the very low friction and wear that may be achieved with these materials. Phenomena accounting for establishment and lifetime of such low-friction regime are proposed. Finally, some open issues concerning vacuum- and space-related applications are discussed.