Effect of Supporting Metal Substrates on the Tribological Properties of Monolayer Graphene

WL Zhao and FL Duan, TRIBOLOGY LETTERS, 68, 32 (2020).

DOI: 10.1007/s11249-020-1267-3

The effect of the adsorption of monolayer graphene (MLG) on metal surfaces nickel (Ni(111), platinum Pt(111) and copper Cu(111) with regard to the nanoscale adhesive friction and wear of MLG was investigated by molecular dynamics simulation of a diamond tip sliding over metal-supported MLG. It was shown that the adsorption of the MLG coating freely on the Ni(111) surface is chemisorption, and adsorption on Pt(111) and Cu(111) surfaces is physisorption. However, beneath the tip, the Pt(111) substrate exhibits a certain chemical weakening effect on MLG due to the contact pressure, while the weakening effect of Pt(111) substrate is weaker than that of the Ni(111) substrate; the Cu(111) substrate has no chemical weakening effect on MLG. This leads to much lower load-carrying capacity for Ni(111)- and Pt(111)-supported MLG (rupturing under 7 and 11 nN, respectively, during sliding) than for Cu(111)-supported MLG (rupturing under 21 nN). During wear, only the Ni(111) substrate shows a chemical weakening effect on MLG at the crack tip, which results in lower tear resistance (providing the main frictional resistance) of Ni(111)-supported MLG compared with Pt(111)- and Cu(111)-supported MLG. The decrease in load-carrying capacity and tear resistance of MLG is due to the weakening of C-C bonds via charge transfer from metal to carbon atoms.

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