Self-healing WS2 tribofilms: An in-situ appraisal of mechanisms

Self-healing tribocoatings are being developed for aerospace applications to improve the lifetime and reduce the surface maintenance of components in motion. Here the tribo-induced self-healing behaviour of a WS2/a-C tribocoating has been evaluated for the first time by in-situ scanning electron microscopy (SEM) to evaluate the mechanisms of damage and self-recovery. In-situ SEM imaging reveals that scratch damage results in coating brittle fracture and spalling, and that Hertzian pressure affects healing rate at early stages of sliding. WS2 nanocrystallites, formed via atomic rearrangement at flexural interfaces, enable the healing of irregular damages and congruently offer superlubrication in vacuum. Such damage control in tribo-service may make flawless coatings an unnecessary prerequisite in tribo-applications.