Abstract
The intermittent 'stick-slip' dynamics in frictional sliding of solid bodies is common in everyday life and technology. This dynamics has been widely studied on a macroscopic scale, where the thermal motion can usually be neglected. However, the microscopic mechanisms behind the periodic stick-slip events are yet unclear. We employ confocal microscopy of colloidal spheres, to study the frictional dynamics at the boundary between two quasi-two-dimensional (2D) crystalline grains, with a single particle resolution. Such unprecedentedly-detailed observations of the microscopic-scale frictional solid-on-solid sliding have never been previously carried out. At this scale, the particles undergo an intense thermal motion, which masks the avalanche-like nature of the underlying frictional dynamics. We demonstrate that the underlying sliding dynamics involving out-of-plane buckling events, is intermittent and periodic, like in macroscopic friction. However, unlike in the common models of friction, the observed periodic frictional dynamics is promoted, rather than just suppressed, by the thermal noise, which maximizes the entropy of the system.
Original language | English |
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Pages (from-to) | 5227-5233 |
Number of pages | 7 |
Journal | Soft Matter |
Volume | 15 |
Issue number | 26 |
DOIs | |
State | Published - 14 Jul 2019 |
Bibliographical note
Publisher Copyright:© 2019 The Royal Society of Chemistry.
Funding
We are grateful to Peter J. Lu for sharing his PLuTARC codes, to Dov Fridman for technical assistance, and to Erio Tosatti for illuminating discussions. This research was supported by the Israel Science Foundation (grant no. 1779/17). Some of the equipment was funded by the Kahn foundation. ABS is partially funded by the UK Engineering and Physical Sciences Research Council grant EP/J007404/1. The paper is dedicated to Prof. Peter Pershan (Harvard University) a trail blazer in Surface Science, on his 85th birthday.
Funders | Funder number |
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Esther B. Kahn Charitable Foundation | |
Engineering and Physical Sciences Research Council | EP/J007404/1 |
Israel Science Foundation | 1779/17 |