Solid lubricants are used in applications where conventional liquid lubricants reach their limits. One of the well-known solid lubricants is graphite, showing good lubrication properties in normal atmosphere but severe wear and high friction in vacuum. This study aims to shine light onto the mechanisms, properties, and limits of graphite lubrication under high mechanical load (> 1 GPa) with sliding and rolling motion.
Previous sliding experiments revealed the in situ formation of a thin carbon layer in the sliding contact. This carbon layer was found to be crucial for a low coefficient of friction (CoF) of 0.10 and exhibited a turbostratic structure revealed by transmission electron microscopy analysis. First experiments under rolling friction hint to the fact that already a slide-to-roll-ratio (SRR) of 5% is sufficient to reciprocate the formation of a similar carbon layer as under pure sliding, but with an increased lifetime. As a next step, the influence of the SRR on the carbon layer formation, CoF, and the lifetime of the coating will be investigated.