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Atomistic Mechanism of Friction-Force Independence on the Normal Load and Other Friction Laws for Dynamic Structural Superlubricity

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posted on 2024-02-20, 15:37 authored by NV Brilliantov, AA Tsukanov, AK Grebenko, AG Nasibulin, IA Ostanin
We explore dynamic structural superlubricity for the case of a relatively large contact area, where the friction force is proportional to the area (exceeding ∼100 nm2) experimentally, numerically, and theoretically. We use a setup composed of two molecular smooth incommensurate surfaces: graphene-covered tip and substrate. The experiments and molecular dynamic simulations demonstrate independence of the friction force on the normal load for a wide range of normal loads and relative surface velocities. We propose an atomistic mechanism for this phenomenon, associated with synchronic out-of-plane surface fluctuations of thermal origin, and confirm it by numerical experiments. Based on this mechanism, we develop a theory for this type of superlubricity and show that friction force increases linearly with increasing temperature and relative velocity for velocities larger than a threshold velocity. The molecular dynamic results are in a fair agreement with predictions of the theory.

History

Author affiliation

Department of Mathematics, University of Leicester

Version

  • VoR (Version of Record)

Published in

Physical Review Letters

Volume

131

Issue

26

Publisher

American Physical Society (APS)

issn

0031-9007

eissn

1079-7114

Copyright date

2023

Available date

2024-02-20

Language

en

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