▎ 摘　　要

An atomic force microscope is used to study the nanoscale frictional characteristics of graphene exfoliated onto weakly adherent silica substrates. Different from the decrease in the friction force with temperature for Si tips sliding on silica substrates, the friction forces for the same tip sliding on a graphene surface have an increasing trend with temperature. Through exploring the morphologies of graphene in both suspended and supported states and at different temperatures, it is found that surface fluctuations are the main reason behind the suppression of the thermal lubrication, which leads to an increase in the friction force with temperature. (C) 2015 AIP Publishing LLC.