▎ 摘　　要

In the present study, we synthesized homogeneous bilayer graphene (BLG) films on the Cu substrate by adopting the hot filament chemical vapor deposition (HFCVD) method. The precise control of the layer number of fabricated graphene films could be obtained by adjusting the flow rate of hydrogen or reactive pressure. Either increasing the flow rate of hydrogen under a fixed reactive pressure or decreasing the reactive pressure with a fixed CH4:H-2 ratio resulted in an increase in the layer number of the synthesized graphene film. We further examined the nanotribological properties of BLG by Atomic Force Microscopy (AFM). The BLG film resulted in an 83%-92.5% reduction in friction when applied on the surface of either copper or SiO2/Si substrates. The obtained coefficients of friction (COFs) were as low as 0.025-0.085. Besides, the critical failure load of the BLG film on the SiO2/Si substrate was measured as 1266 +/- 28 nN in a progressive-force scratching test, in which we used a diamond tip with a radius of 10 nm. The corresponding actual contact pressure was estimated at as high as 14.15 GPa, according to Derjaguin-Muller-Toporov model, which was enhanced by over one order of magnitude compared with that obtained for the bare SiO2/Si substrates (1.2 GPa). The results achieved in the present study demonstrate that homogeneous BLG films with promising lubricity and superior wear resistance could be synthesized in the HFCVD process, which, we believe, provides an effective and controllable approach for promoting the application of BLG films as a nanoscale solid lubricant in a variety of Nano/Micro Electromechanical Systems devices.