Preparation And Tribological Properties Of Ag/Carbon Based Nanocomposites

Currently,soft metal Ag nanoparticles exhibit broad prospects in friction lubrication due to their low shear strength,good embedding ability and ductility.With the rapid development of science and technology,the sliding interface in the field of mechanical systems requires extremely low friction and excellent wear resistance,which imposes stringent requirements on friction-lubricating materials.Meanwhile,traditional single-component Ag nanoparticles can not meet the extremely needs of today's friction conditions.Nanomaterials,such as graphene,carbon nanotubes and carbon spheres,possess excellent self-lubricating properties,which have been extensively studied in the field of lubrication.Based on this,this paper uses graphene,carbon nanotubes and carbon spheres to recombine with Ag nanoparticles to improve the dispersibility and tribological properties of Ag nanoparticles in lubricating oil.This method opens up a new route for the preparation of carbon-based nanocomposites with excellent lubricating properties.Its main contents are as follows:(1)Ag nanoparticles were in situ grown on dopamine-functionalized grapheme oxide by hydrothermal reduction to prepare highly active GO-PDA/Ag nanocomposites.The tribological property test showed that GO-PDA/Ag nanocomposites have the best anti-wear and anti-friction effect,both better than Ag nanoparticles,GO and pure oil.The excellent tribological properties are due to the fact that the GO sheet layered structure in the sheet-like GO-PDA/Ag composite can reduce the friction and wear by interlayer sliding,and which protect the friction surface.Meanwhile,between the Ag nanoparticles and the GO nanosheets can play synergistic lubrication effect.(2)The carbon nanotubes were modified by dopamine,and Ag nanoparticles were prepared in situ on the surface of functionalized carbon nanotubes by hydrothermal reduction to prepare CNTs-PDA/Ag nanocomposites.The tribological properties of CNTs-PDA/Ag nanocomposites as lubricant additives were studied.The results show that CNTs-PDA/Ag composites have the best antiwear and antifriction effect compared with pure Ag nanoparticles and CNTs.Carbon nanotubes have a large aspect ratio,which acts as a repair and micro-bearing during the friction process.At the same time,Ag nano-particles and CNTs can exert synergistic lubrication,and thus exhibit excellent anti-friction performance.(3)Using glucose as a carbon source,the core-shell Ag@C nanospheres with uniform morphology were prepared by one-step hydrothermal method.The Ag nanoparticles acted as the core and the carbon spheres acted as the shell to effectively prevent the Ag core from being oxidized.The tribological properties of Ag@C nanospheres as lubricant additives were studied.The results show that Ag@C nanospheres have the best tribological properties compared to pure Ag nanoparticles,carbon spheres and pure oils.The superior lubrication performance is due to the fact that the Ag@C nanosphere acts as a rolling bearing,which converts sliding friction into rolling friction.At the same time,Ag and carbon spheres can exert their synergistic lubrication effect.