Led by nanoscientist Ani Sumant of Argonne's Centre for Nanoscale Materials and Argonne Distinguished Fellow Ali Erdemir of Argonne's Energy Systems Division, the five-person team combined diamond nanoparticles, small patches of graphene and a diamond-like carbon material to create the highly-desirable property in which friction drops to near zero.
According to the research paper from 14 May's Science Express entitled 'Macroscale superlubricity enabled by graphene nanoscroll formation', the graphene patch rolls itself around the diamond particles as they rub up against a large diamond-like carbon surface, creating something that looks like a ball bearing on the nanoscopic level.
By creating the graphene-encapsulated diamond ball bearings, or 'scrolls', the team found a way to translate the nanoscale superlubricity into a macroscale phenomenon. Because the scrolls change their orientation during the sliding process, enough diamond particles and graphene patches prevent the two surfaces from becoming locked in state. The team used large-scale atomistic computations on the Mira supercomputer at the Argonne Leadership Computing Facility to prove that the effect could be seen not merely at the nanoscale but also at the macroscale.
Sumant said, "The knowledge gained from this study will be crucial in finding ways to reduce friction in everything from engines or turbines to computer hard disks and microelectromechanical systems."
However, while superlubricity was maintained in dry conditions, in a humid environment this was not the case. "We observed that the scroll formation was inhibited in the presence of a water layer, therefore causing higher friction," explained co-author and Argonne computational nanoscientist Subramanian Sankaranarayanan.