Observation of the Amontons-Coulomb law on the nanoscale: Frictional forces between MoS ₂ flakes and MoS ₂ surfaces

Abstract

The MoS2 flake moves on MoS2 in such a way that the stacking of the sulphur basal plane of MoS2 is maintained. The frictional forces between MoS2 surfaces are clearly proportional to the loading force although they depend strongly on the movement of the MoS2 flake. The Amontons-Coulomb law is excellently satisfied at loading forces in the range of 1–120 nanonewtons. The frictional coefficient between MoS2 surfaces along the direction [ 101̄0] of the MoS2(0001) surface is estimated to be approximately 0.003.

Effects of vdW Interaction and Electric Field on Friction in MoS2

“…Thus, the predicted maximum frictional forces based on this approach can be expected to be generally larger than the experimental values. These limitations notwithstanding our results give a trend in the sliding behavior as a function of a normal load, in close agreement with previous experimental measurements [8].…”

“…As the Amontons's friction law expected, both energy corrugations and maximum lateral frictional forces monotonically increase with normal loads. It shows that the interlayer friction of MoS 2 on the atomic scale also obeys the basic friction law observed experimentally by Miura [8]. We have further studied the vdW interactions on friction of MoS 2 layers.…”

“…Singer [7] have reported the friction coefficient of thin MoS 2 coatings decreases as the load increases. Moreover, the Amontons-Coulomb law has been observed on the nanoscale, when a MoS 2 flake moves on a MoS 2 surface [8]. All these evidences imply the need for a clear understanding of its tribological properties at the atomistic level, and particular attention must also be paid to unraveling the nature of the interlayer forces, as an interplay of electrostatic interactions, van der Waals (vdW) forces, and Pauli repulsion [2,[9][10][11][12].…”

Interlayer commensurability and superlubricity in rigid layered materials

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] This important characteristic has its origin in their nanoscopic anisotropic crystal structure consisting of strong covalent intra-layer bonding and weaker dispersive interlayer interactions. 15 One important consequence of this unique structure is the fact that the layers may slide on top of each other while overcoming relatively small energetic barriers.…”

Numerical study of friction of flake and adsorbed monolayer on atomically clean substrate

“…Here we study one of the most simple case of friction, friction on atomically clean substrate. Frictional force microscope (FFM) [5,6] and Quartz crystal microbalance (QCM) technique [7,8,9] enable to investigate friction of such systems experimentally and many interesting observations are reported. Numerical experiments also had been playing an important role in the study of friction of such systems.…”