Research on superlubric carbonic materials

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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 on fine structures of superlubric carbonic materials(2) Development of frictional force microscopy which can measure a friction force of piconewton. (3)Discovery of novel superlubric system. It was able to intercalate C_<60> molecules into graphite films using chemical and thermal treatments. The C_<60>intercalated graphite films consist of alternating close-packed C_<60> monolayers and graphite layers(graphenes). When the loading increases up to 100nN, friction force map provides clear periodic pattern. Interestingly, this periodicity reflects a C_<60> close-pack structure of him, which indicates that the mobility of C_<60>is frozon by the squeeze of graphite walls and/or by the creation of a chemical bonding between C_<60> molecules. The friction mechanism of these films is expected to relate to exhibit a multistage sliding assisted by their movements. Stationary zero friction occurs at a quite large area of 2.3mmx2.3nm in size, and no friction appears for any sliding direction, which is a tremendously important discovery for the realization of nano-and micromachines and for a new and prominent industry.