Tribology of the lubricant quantized-sliding state

Abstract

In the framework of Langevin dynamics, we demonstrate clear evidence of the peculiar quantized sliding state, previously found in a simple 1D boundary lubricated model [Phys. Rev. Lett. 97, 056101 (2006)], for a substantially less idealized 2D description of a confined multi-layer solid lubricant under shear. This dynamical state, marked by a nontrivial ``quantized'' ratio of the averaged lubricant center-of-mass velocity to the externally imposed sliding speed, is recovered, and shown to be robust against the effects of thermal fluctuations, quenched disorder in the confining substrates, and over a wide range of loading forces. The lubricant softness, setting the width of the propagating solitonic structures, is found to play a major role in promoting in-registry commensurate regions beneficial to this quantized sliding. By evaluating the force instantaneously exerted on the top plate, we find that this quantized sliding represents a dynamical ``pinned'' state, characterized by significantly low values of the kinetic friction. While the quantized sliding occurs due to solitons being driven gently, the transition to ordinary unpinned sliding regimes can involve lubricant melting due to large shear-induced Joule heating, for example at large speed.

11 pages, 11 figures

References in corpus (10)

• Exactly quantized dynamics of classical incommensurate sliders
• Static friction on the fly: velocity depinning transitions of lubricants in motion
• Impact of molecular structure on the lubricant squeeze-out between curved surfaces with long range elasticity
• Asymmetric frictional sliding between incommensurate surfaces
• Solitons and exact velocity quantization of incommensurate sliders
• Lubricated friction between incommensurate substrates
• Role of transverse displacements for a quantized-velocity state of the lubricant
• Kink plateau dynamics in finite-size lubricant chains
• Hysteresis from dynamically pinned sliding states
• Nonlinear hysteretic behavior of a confined sliding layer

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• Soliton dynamics in a solid lubricant during sliding friction
• Sliding states of a soft-colloid cluster crystal: Cluster versus single-particle hopping