Issue Date: February 1, 2016
Graphene Balls Reduce Friction
A suspension of crumpled graphene balls in oil can reduce friction and wear between metal surfaces sliding over one another better than commercial lubricants, according to a study (Proc. Natl. Acad. Sci. USA 2016, DOI: 10.1073/pnas.1520994113). The investigation, which was conducted by Northwestern University materials scientists Yip-Wah Chung and Jiaxing Huang and coworkers, was inspired by work carried out by Huang’s group in 2011 showing that crumpled graphene balls resist agglomeration, much like wadded paper balls. Many lubricants are formulated with microscopic particles of graphite and various inorganic compounds to increase slipperiness and reduce wear, for example, between moving engine parts. But repeated frictional forces can cause these particles to agglomerate, reducing a lubricant’s effectiveness. Having discovered that crumpled graphene balls don’t stick together, the Northwestern team tried using them as lubricant additives. Results of tribology tests, in which a steel pin was dragged across a steel plate, show that in terms of reducing friction and wear, a standard poly(α-olefin) oil containing crumpled graphene balls is a better lubricant than some commercial products and better than the same oil mixed with other carbon additives.
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