| In recent years,the emerging carbon nanomaterial-graphene is attracting increasingly more attention in the field of friction with its excellent tribological property.However,because graphene aggregates easily,making it difficult to be stable but disperse in water.Oxidized graphene(GO)is a kind of derivative product of graphene,which is also composed of a large amount of monolayer graphene.It has a two-dimensional planar structure with self-lubricating property.During the rubbing process,GO can be adsorbed on the surface of the friction pair,to prevent the direct friction between the metal friction pairs,and reduce the friction between the friction pairs by the relative slippage between the carbon layers.In the meanwhile,GO also has a large number of oxygen-containing functional groups,which will increase the dispersion of GO in the water greatly,to form stable water dispersion,thus playing a certain lubrication effect.However,the carboxyl at the edge of GO will corrode the metal friction pair during the friction process,causing corrosion wear,which will affect the performance of GO as an additive.We can use alcohols to have the esterification reaction with the carboxyl on GO to reduce the content of carboxyl,so as to reduce the effect of corrosion wear.In this paper,graphene oxide was prepared by the improved Hummers method.Polyhydroxylate modified graphite(GOOH-G and GOOH-E)is prepared by taking advantage of polyhydroxylated raw material(glycerol or ethylene glycol)and graphene oxide(GO).Its microstructure is observed with atomic force microscope(AFM)and scanning electron microscope(SEM).The structural characterization is carried out with infrared spectrometer(IR).Besides,its stability and corrosivity in water is evaluated.The anti-wear and antifriction performance of GOOH-G in water base and polyethylene glycol as lubricant additive is investigated with four-ball friction and wear testing machine.And the anti-wear and antifriction performance of GOOH-E in polyethylene glycol is also investigated.In addition,the tribological comparison test is carried out with GO under same experimental conditions.Besides,the chemical components of its rubbed surface and friction film are investigated with SEM and energy disperse spectroscopy(EDS).The main contents and results of this paper are as follows:1.Two kinds of polyhydroxylate modified graphite were synthesized (GOOH-G& GOOH-E).2.The tribological properties of GO,GOOH-G and GOOH-E in aqueous and polyethylene glycol systems were investigated.According to the experimental results: the stability of hydroxylated GO in water and polyethylene glycol is similar compared to GO.However,corrosiveness of hydroxylated GO is weaker but possesses better tribological performance.After GOOH-G or GOOH-E additive is used,more carbon elements can be detected on the friction pair surface compared to that after GO is used.It thus indicates that it could be better absorbed on the friction pair surface to play the role of anti-wear and friction.As for GOOH-E,due to its better compatibility with polyethylene glycol,results in more excellent tribological properties. |
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