Measurement on critical shear stress of circular point contact utilizing Atomic Force Microscope

We propose Bowdon-Johnson-Kendall-Roberts model to measure the critical shear stress of circular point contact, and the critical shear stress map is constructed through the lateral force mode and force map mode of Atomic Force Microscope to research the interface property of nanomaterials. The mean critical shear stresses are measured as 0.24 MPa for monolayer MoS2 and 0.69 MPa for graphene. MoS2 nanosheet and graphene are of the lower critical shear stress and friction coefficient than those of the bulk materials, which are good agreement with the regularities in nanotribology. The critical shear stress can be used to not only quantitatively characterize the frictional properties, but also analyze the friction at different loading stages. The critical shear stress map would play an important role in sliding contact of nanomaterials for the drive part design and nanotribological reliability of nanoelectronic mechanical system.