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arXiv · 2411.03078

Chemifriction and Superlubricity: Friends or Foes?

Penghua Ying·Xiang Gao·Amir Natan·Michael Urbakh·Oded Hod
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Abstract

The mechanisms underlying chemifriction, i.e. the contribution of interfacial bonding to friction in defected twisted graphene interfaces are revealed using fully atomistic machine-learning molecular dynamics simulations. This involves stochastic events of consecutive bond formation and rupture, that are spatially separated but not necessarily independent. A unique shear-induced interlayer atomic transfer healing mechanism is discovered that can be harnessed to design a run-in procedure to restore superlubric sliding. This mechanism should be manifested as negative differential friction coefficients that are expected to emerge under moderate normal loads. A physically motivated phenomenological model is developed to predict the effects of chemifriction in experimentally relevant sliding velocity regimes. This allows us to identify a distinct transition between logarithmic increase and logarithmic decrease of frictional stress with increasing sliding velocity. While demonstrated for homogeneous graphene interfaces, a similar mechanism is expected to occur in other homogeneous or heterogeneous defected two-dimensional material interfaces.

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Penghua Ying, Xiang Gao, Amir Natan, Michael Urbakh, Oded Hod. 2024-11-05. Chemifriction and Superlubricity: Friends or Foes?. https://doi.org/10.1021/acs.jpclett.5c00193

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