Effects of high-temperature annealing on tribological properties of graphene

To explore the effects of the tribological property changes of the graphene on its performance as a solid lubricant at the high-temperature, the tribological properties of single-layer graphene after annealing in air at different temperatures were studied by an atomic force microscope (AFM), and the changes of the friction and the adhesion before and after annealing at different temperatures were compared. The defects of the graphene were detected by Raman spectroscopy and the defect density of the graphene was calculated. Finally, the relationship between the friction force of single-layer graphene and the defect density was established under different loads. Experimental results show that after annealing in air, the friction and the adhesion of the graphene are significantly enhanced. After annealing at 300℃ in air, the friction of the graphene is about 2-3 times that of the original graphene, and the adhesion force roughly doubles. Moreover, the higher the annealing temperature is, the more obvious the enhancement effect of the friction and the adhesion is. The detectable defects initially appear between 200 and 300℃, and the defect density increases with the increase of the annealing temperature. The structural defects of the graphene after high-temperature annealing are the cause of important changes in the friction and the adhesion of single-layer graphene. © 2021, Editorial Department of Journal of Southeast University. All right reserved.