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Title
Japanese: 
English:Time-lapse Nanoscopy of Friction in the non-Amonton and non-Coulomb Regime 
Author
Japanese: 石田 忠, 佐藤 隆昭, 小熊 正嗣, 石川 貴大, 板村 賢明, 合田 圭介, 佐々木 成朗, 藤田 博之.  
English: T. Ishida, Takaaki Sato, Masatsugu Oguma, Takahiro Ishikawa, Noriaki Itamura, Keisuke Goda, Naruo Sasaki, H. Fujita.  
Language English 
Journal/Book name
Japanese: 
English:Nano Letters 
Volume, Number, Page Vol. 15        pp. 1475-1480
Published date Oct. 20, 2014 
Publisher
Japanese: 
English:American Chemical Society 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
English: 
Abstract Originally discovered by Leonard da Vinci in the 15th century, the force of friction is directly proportional to the applied load (known as Amontons’ first law of friction). Furthermore, kinetic friction is independent of the sliding speed (known as Coulomb’s law of friction). These empirical laws break down at high normal pressure (due to plastic deformation) and low sliding speed (in the transition regime between static friction and kinetic friction). An important example of this phenomenon is friction between the asperities of tectonic plates on the Earth. Despite its significance, little is known about the detailed mechanism of friction in this regime due to the lack of experimental methods. Here we demonstrate in situ time-lapse nanoscopy of friction between asperities sliding at ultralow speed (∼0.01 nm/s) under high normal pressure (∼GPa). This is made possible by compressing and rubbing a pair of nanometer-scale crystalline silicon anvils with electrostatic microactuators and monitoring its dynamical evolution with a transmission electron microscope. Our analysis of the time-lapse movie indicates that superplastic behavior is induced by decrystallization, plastic deformation, and atomic diffusion at the asperity-asperity interface. The results hold great promise for a better understanding of quasi-static friction under high pressure for geoscience, materials science, and nanotechnology.

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