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 [ 100] of the MoS₂(0001) surface is estimated to be approximately 0.003.