Superlubric nanomachine by use of molecular bearings

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It is one of the ultimate goals of tribology researchers to realize an ideal friction-free machinery system with zero energy consumption. Since the proposal of the concept of an ideal frictionless sliding, fundamental studies on ultralow friction mechanism have been carried out to date based on mainly two different mechanisms, incommensurate contact and weak interfacial interaction. However there have been few studies aim of which is for practical use in lubrication engineering. Recently we have shown that a C_<60> monolayer system confined by graphite walls exhibits ultralow dynamic friction. In this project, three main subjects have been planned : (1)Research of superlubric system due to nanogear and molecular bearings. (2)Theoretical research of superlubric system. (3)Discovery of novel superlubric system. In particular, in this study, we can appeal that a C_<60> intercalated graphite film with the area of 2.3x2.3mm^2 prepared by chemical and thermal treatments exhibits ultralow friction with quite an excellent friction coefficient μ<0.001 which is smaller than μ=0.002 for MoS_2 and μ=0.001 for graphite. It can be expected that the ultralow friction is induced by internal sliding of alternating close-packed C_<60> monolayers and graphite layers. Our results demonstrate ultralow frictional properties can be controlled by the intercalated materials. C_<70> intercalated graphite exhibits not so good an ultralow frictional feature as C_<60> intercalated graphite. The present study provides a novel lubrication system and an indication of what solid lubrication systems will be like in the future.