The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by t...The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by the same method.The results show that the Cu-GNSs composites exhibit higher relative density,microhardness and bending strength compared with Cu-Gr composites with the same volume fraction of GNSs and Gr.Moreover,the friction coefficients and wear rates reduce significantly by the addition of GNSs,whereas the limited impact on reducing friction and wear is found on graphite.The abrasive and delamination wear are the dominant wear mechanisms of the composites.It is believed that the superior mechanical and tribological performances of Cu-GNSs composites are attributed to the unique strengthening effect as well as the higher lubricating efficiency of graphene nanosheets compared with those of graphite,which demonstrates that GNS is an ideal filler for copper matrix composites,acting as not only an impactful lubricant but also a favorable reinforcement.展开更多
The tribological properties of graphene oxide(GO) nanosheets and modified diamond(MD) nanoparticles with excellent water-solubility were investigated.GO nanosheets were synthesized using carbon fibers with a regular a...The tribological properties of graphene oxide(GO) nanosheets and modified diamond(MD) nanoparticles with excellent water-solubility were investigated.GO nanosheets were synthesized using carbon fibers with a regular and uniform size,the lateral size being around 30 nm and the thickness being 2 or 3 nm,while MD nanoparticles were about 30 nm in the three dimensions.The friction properties of ceramics were improved by GO nanosheets or MD nanoparticles used as additives in water-based lubrication,though the effects of two nanoparticles were quite different.For GO nanosheets,the friction coefficient at the beginning decreased sharply from 0.6 to 0.1,as compared with the dionized water lubrication.At the same time,the running-in period was shortened from 2000 s to 250 s.A steady state characterized by ultralow friction(friction coefficient=0.01) was obtained after the running-in period.In the case of MD nanoparticles,the friction coefficient stayed at 0.1 without further decrease during the whole experiment.Based on the observation of wear scar and characterization of remains on the wear track,the positive effect of GO nanosheets was attributed to their lamellar structure and geometric size.MD nanoparticles reduced friction by forming the regularly grained surface on the mating surfaces,and prevented further reduction in steady-state friction coefficient owing to their larger size and hardness.In conclusion,GO nanosheets exhibited favorable potential as an effective additive for water-based lubrication.展开更多
文摘The mechanical and tribological properties of hot-pressed copper-based composites containing different amounts of graphene nanosheets（GNSs） are compared with those of copper-graphite（Gr） composites fabricated by the same method.The results show that the Cu-GNSs composites exhibit higher relative density,microhardness and bending strength compared with Cu-Gr composites with the same volume fraction of GNSs and Gr.Moreover,the friction coefficients and wear rates reduce significantly by the addition of GNSs,whereas the limited impact on reducing friction and wear is found on graphite.The abrasive and delamination wear are the dominant wear mechanisms of the composites.It is believed that the superior mechanical and tribological performances of Cu-GNSs composites are attributed to the unique strengthening effect as well as the higher lubricating efficiency of graphene nanosheets compared with those of graphite,which demonstrates that GNS is an ideal filler for copper matrix composites,acting as not only an impactful lubricant but also a favorable reinforcement.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805086,50730007)Tsinghua University Initiative Scientific Research Programthe Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No.51021064)
文摘The tribological properties of graphene oxide(GO) nanosheets and modified diamond(MD) nanoparticles with excellent water-solubility were investigated.GO nanosheets were synthesized using carbon fibers with a regular and uniform size,the lateral size being around 30 nm and the thickness being 2 or 3 nm,while MD nanoparticles were about 30 nm in the three dimensions.The friction properties of ceramics were improved by GO nanosheets or MD nanoparticles used as additives in water-based lubrication,though the effects of two nanoparticles were quite different.For GO nanosheets,the friction coefficient at the beginning decreased sharply from 0.6 to 0.1,as compared with the dionized water lubrication.At the same time,the running-in period was shortened from 2000 s to 250 s.A steady state characterized by ultralow friction(friction coefficient=0.01) was obtained after the running-in period.In the case of MD nanoparticles,the friction coefficient stayed at 0.1 without further decrease during the whole experiment.Based on the observation of wear scar and characterization of remains on the wear track,the positive effect of GO nanosheets was attributed to their lamellar structure and geometric size.MD nanoparticles reduced friction by forming the regularly grained surface on the mating surfaces,and prevented further reduction in steady-state friction coefficient owing to their larger size and hardness.In conclusion,GO nanosheets exhibited favorable potential as an effective additive for water-based lubrication.
