Preparation And Tribological Performance Of Crystalline Graphene Based Nanocomposites

With the development of industry,the use of machinery equipment hasbecome more and more important,which causes the friction during the running of mechanical equipment.The adding lubricating oil into the surfaces of relatively moving parts is efficient way to achieve the purpose anti-friction and anti-wear,which can significantly decrease the friction between the surfaces of moving parts.With the development of tribology and nanotechnology,lubrication additives are used as an important approach to improve the performance of lubricating oils.Currently,many researchers focus on the introduction of nanomaterials into tribology for exploration and research.Under harsh conditions,the nanomaterials exhibit the excellent anti-wear and anti-friction properties,and load-bearing capacity,which hold a great potential in friction applications.In this paper,in-situ growth of CeO₂ or CeF₃nanoparticles onto the surface of reduced graphene oxide?rGO?was achieved by the hydrothermal method to obtain graphene-based nanocomposites.The influence of preparation process conditions on the microstructure of the composites was studied in detail.The relationship between the microstructure and the tribological properties of the composites was investigated.As a result,the new type of nano-lubricant additives with high efficiency can be obtained.The main research contents are as follows:?1?Preparation and tribological properties of CeO₂/rGO nanocomposites.The CeO₂/rGO nanocomposites have been synthesized by hydrothermal reaction,and the GO was used as a precursor.The effect of the weight ratio between GO and Ce?NO₃?₃·6H₂O on the microstructure of the nanocomposites was investigated.The results showed that CeO₂ nanoparticles with particle sizes of 4-9 nm were uniformly distributed on rGO sheets.The tribological results showed that CeO₂/rGO nanocomposites significantly improved the tribological properties of base oil.Compared with other additives,CeO₂/rGO nanocomposites have the better anti-wear and anti-friction properties.The possible friction mechanism is that the lamellar structure of rGO can reduce friction and wear through interlaminar sliding;meanwhile CeO₂ nanoparticles play an important role in microsphere and changing the sliding friction between worn surfaces into rolling friction.?2?Preparation and tribological properties of CeF₃/rGO nanocomposites.The CeF₃/rGO nanocomposites have been synthesized by hydrothermal reaction,and the GO was used as a precursor.The results showed that CeF₃ nanoparticles with particle size of 8-10.5 nm were uniformly distributed on rGO.The tribological measurements showed that the prepared CeF₃/rGO nanocomposites have the better anti-wear and anti-friction effect than those of other additives.The tribological properties of the base oil can also be improved to some extent.Finally,the friction mechanism of nano-lubricant additives was discussed.?3?Preparation and tribological properties of cerium oxide/graphene/carbon nanotube?CeO₂/rGO/CNTs?nanocomposites.The CeO₂/rGO/CNTs nanocomposites were prepared by hydrothermal method,and the GO/CNT was used as a precursor.GO and acidified CNTs can form a stable structure by?-?bond.The particle size of CeO₂ nanoparticles on carbon materials is about 3-3.5 nm.The tribological test results showed that the CeO₂/rGO/CNTs nanocomposites have the high dispersity in the base oil,and significantly improve the lubricating properties of the base oil.The possible friction mechanism is that the lamellar structure of rGO can reduce friction and wear through interlaminar sliding;meanwhile CeO₂ nanoparticles play an important role in microsphere and CNTs act as bearings,than reducing the friction and wear of the friction pairs.