Friction and wear characteristics of multi-layer graphene films investigated by atomic force microscopy

Friction and wear characteristics of multi-layer graphene films deposited on a Si substrate by mechanical exfoliation were investigated by atomic force microscopy (AFM). The graphene films consisted of a few layers of carbon basal plane. The number of graphene layers was determined by AFM and Raman spectroscopy. For the AFM friction measurement, loads in the range of − 5 to 30 nN were applied on the Si tip that slid against the graphene specimen. It was found that graphene films exhibited much lower friction (from 0.36 to 0.62 nN) than bare Si surface (from 1.1 to 4.3 nN) when the applied loads ranged from 3 to 30 nN. The wear characteristics were also assessed using the AFM. Detectable wear of graphene was generated when sliding was performed for 100 cycles under 5 μN applied load. The wear mechanism of graphene was proposed to be due to breakage of in-plane bonds between carbon atoms and shearing at the interface of graphene layers.