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In situ transmission electron microscopy studies reveal how nanoparticles move in a sliding contact.
Ever since the discovery in1985 of carbon "buckmisterfulleres," named for the inventor of geodesic domes that the structure resembles, the notion of using such molecules as nano-sized ball bearings has appealed to tribologist. It also is possible to synthesize inorganic analogs of these nanoparticle systems with other layered compounds such as molybdenum or tungsten disulfides, which have been shown to reduce friction and to be potentially useful oil additives or solid lubricants.
Since both MoS., and WS. are layered compounds held together by weak van der Waals interactions (similar to those in graphite) the layers are able to easily slide over each other and provide low-friction films. However, the fact that the inorganic fullerenes reduce friction provides no insights into whether these operate as nano-sized ball bearings or whether they break up...