Effect of rotational speed on the interfacial nano-structural evolution and friction behavior of hydrogenated fullerene-like carbon (FLC) films in vacuum

Hydrogenated fullerene-like carbon (H-FLC) film is of great potential in reaching macro-scale ultra-low friction. But its friction regime is still under debate. In this study, friction behavior of H-FLC was investigated in vacuum and ambient under various rotational speeds. Results show that friction coefficient is in negative correlation with rotational speed. At rotational speed of 500 rpm, H-FLC film reached ultra-low friction (0.015). Detailed nano structure evolution research indicates that the odd carbon ring fraction at sliding interface is the origin of H-FLC's low friction. Namely, randomly oriented pentagonal and heptagonal carbon rings were rearranged in wear track, which enhanced the FL content. This work corroborated that rehybridization at frictional interface of H-FLC plays an important role in its ultra-low friction.

Automated summary

The study found that the friction coefficient of H-FLC film is negatively correlated with rotational speed, reaching ultra-low friction at 500 rpm. Detailed nano structure evolution research indicates that the odd carbon ring fraction at the sliding interface is the key to H-FLC's low friction, with rearranged pentagonal and heptagonal carbon rings enhancing the fullerene-like carbon content. This work corroborated the significant role of rehybridization at the frictional interface in achieving ultra-low friction of H-FLC.