Effects of Pt cylinder arrays on macro-tribological properties of graphene and the SiO2/Si substrate

Hexagonal arrays of Pt cylinders with different diameters were prepared using magnetron sputtering technology onto SiO2/Si substrates and also on graphene which was previously deposited onto a SiO2/Si substrate. Friction and wear properties of different samples were investigated. The surface morphologies and composition at the center of the wear track were analyzed by scanning electron microscopy, Raman spectra and X-ray photoelectron spectroscopy. Results indicated that Pt cylinders with different diameters acted as very strong pinning centers for the sliding of graphene sheets, and affected the subsequent friction. The higher the Pt surface coverage, the stronger the effect of Pt cylinders on the lubrication performance. As such, the friction and wear of large-diameter Pt cylinders on graphene and the SiO2/Si substrate were more effective in reducing the friction. On the contrary, for small-diameter Pt cylinders, the interaction between graphene and Pt cylinders played a key role in the improvement of macro-tribological properties. Overall, the Pt cylinders played an important lubrication role on the friction and wear. Graphene introduced as an adhesion layer between Pt cylinders and the SiO2/Si substrate could support both deformed and undeformed Pt cylinders.