A near-wearless and extremely long lifetime amorphous carbon film under high vacuum

Abstract

Prolonging wear life of amorphous carbon films under vacuum was an enormous challenge. In this work, we firstly reported that amorphous carbon film as a lubricant layer containing hydrogen, oxygen, fluorine and silicon (a-C:H:O:F:Si) exhibited low friction (~0.1), ultra-low wear rate (9.0 × 10 ^–13 mm ³ N ^–1 mm ^–1) and ultra-long wear life (>2 × 10 ⁶ cycles) under high vacuum. We systematically examined microstructure and composition of transfer film for understanding of the underlying frictional mechanism, which suggested that the extraordinarily excellent tribological properties were attributed to the thermodynamically and structurally stable FeF ₂ nanocrystallites corroborated using first-principles calculations, which were induced by the tribochemical reaction.