Origin of friction in films of horizontally oriented carbon nanotubes sliding against diamond

Carbon nanotube films were fabricated by a new deposition technique that can minimize carbon nanotube rolling/slipping when sliding against diamond. Molecular dynamics simulations were performed to understand the friction mechanisms. Results clarify the controversial arguments in the literature and conclude that the atomically smooth surface without dangling atoms and durability of the atomic lattice structure of carbon nanotubes makes them a good solid lubricant with an ultra-low coefficient of friction of around 0.01.