Anisotropy of Graphene Nanoflake Diamond Interface Frictional Properties

Abstract

Using molecular dynamics (MD) simulations, the frictional properties of the interface between graphene nanoflake and single crystalline diamond substrate have been investigated. The equilibrium distance between the graphene nanoflake and the diamond substrate has been evaluated at different temperatures. This study considered the effects of temperature and relative sliding angle between graphene and diamond. The equilibrium distance between graphene and the diamond substrate was between 3.34 Å at 0 K and 3.42 Å at 600 K, and it was close to the interlayer distance of graphite which was 3.35 Å. The friction force between graphene nanoflakes and the diamond substrate exhibited periodic stick-slip motion which is similar to the friction force within a graphene–Au interface. The friction coefficient of the graphene–single crystalline diamond interface was between 0.0042 and 0.0244, depending on the sliding direction and the temperature. Generally, the friction coefficient was lowest when a graphene flake was sliding along its armchair direction and the highest when it was sliding along its zigzag direction. The friction coefficient increased by up to 20% when the temperature rose from 300 K to 600 K, hence a contribution from temperature cannot be neglected. The findings in this study validate the super-lubricity between graphene and diamond and will shed light on understanding the mechanical behavior of graphene nanodevices when using single crystalline diamond as the substrate.

Mixed sp2–sp3 Nanocarbon Materials: A Status Quo Review

“…The formation of a graphene-on-diamond structure by the graphitization of a diamond (111) surface was also reported by Tokuda and co-workers [74]. The authors observed that the process consists of two steps-formation of an atomically flat diamond (111) surface by homoepitaxial lateral growth and graphitization.…”

“…The same collective also elucidated the atomistic mechanism behind the experimentally observed low friction of these all-carbon lubricants [110]. The low friction at the GN-diamond interface was also proposed by DFT calculations [99] and by molecular dynamics simulations [111]. The theoretical studies suggested that the best lubricity is attained when the GN slides along its armchair direction.…”

“…Nevertheless, the charge transfer between the GN and the diamond depends on the phase orientation of the diamond surface. While no charge transfer between GN and diamond (100) surfaces occurs, p-type or n-type doping on GN can be observed on the (111) surface. The interaction can be further modified via diamond doping; nevertheless, the GN keeps its aromatic character [101].…”

“…Also, the adhesion of a GN monolayer onto a diamond (111) surface with born and nitrogen doping was investigated by first-principle calculations [101,113]. The authors concluded that the GN kept its aromatic character for all terminations and only a moderate charge transfer from the GN to the diamond surface occurs.…”

Graphene – Diamond Nanomaterials: A Status Quo Review

“…The frictional properties of the interface between graphene nanoflake and singlecrystalline diamond substrate have been investigated by molecular dynamics simulations [90]. Generally, the friction coefficient was lowest when a graphene flake slid along its armchair direction and the highest when it slid along its zigzag direction.…”