Friction Performance And Long-term Test Of Grease Containing Modified Carbon Nanomaterials

With the increasing development of industry,the precision and service strength of mechanical equipment are increasing.To provide better lubrication and protection,the grease must continuously develop in low torque,high extreme pressure,long life,and corrosion resistance to meet the demand.Adding solid additives into lubricating grease is an important method to improve the wear resistance of lubricating grease.With the continuous development of carbon nano-material technology and industry,more and more researches on carbon nano-lubricating additives emerge,but the agglomeration problem of carbon nano-particles in the lubricating process has not been properly solved.Besides,due to the different dimensions of carbon nanomaterials and their different mechanisms of action on improving lubrication performance,there may be synergistic effects of multi-dimensional additive lubrication mechanisms,and there are few pieces of research on this aspect at present.Due to the diversification of lubrication mechanisms,multi-dimensional compound additives will further enhance the antifriction performance of lubricating grease.Modified graphene(MR-GO)and carbon nanotubes(M-CNT)obtained by lipophilic modification of graphene and carbon nanotubes.Scanning electron microscope(SEM),Fourier transform infrared spectrometer(FTIR),the thermal analyzer(TG)and X-ray diffraction(XRD)were used to characterize and analyze the carbon nano-materials before and after modification,and the effect of modification on the tribology performance of carbon nano-additives was tested by tribology test.The results showed that the modified molecules were successfully grafted on the surface of carbon nanoparticles,making them lipophilic and avoiding the reaction of lubrication caused by agglomeration.To test the long-term performance of lubricating grease more conveniently and in time,this study designed and manufactured a bearing tester based on the principle of the mainstream tester and the failure principle of lubricating grease,verified the feasibility of changing the tester,preliminarily designed the long-term performance test method of lubricating grease,and tested the experimental samples.The tribology properties of single additive and compound additive samples were tested by the four-ball test.The data showed that the optimal content of a single additive was 0.04 wt%,and the diameter of wear spot was reduced by 20%.The lubricating grease compounded by MR-GO & M-CNT has good anti-friction performance,and its wear spot diameter is reduced by 35% relative to the base grease and 19% and 27% respectively relative to a single additive.Scanning electron microscope photos show that both MR-GO and M-CNT can improve the roughness of the friction surface.The long-term performance test results show that the carbon nano-additive can prolong the failure time of the bearing,and the compounded sample has a better effect.Under the cooperation of the two additives,the self-repairing effect of the friction surface is more diversified,so that the roughness of the wear surface is reduced,the average friction coefficient of the friction surface is lower,and the friction surface is more stable with the increase of the friction duration,thus forming a stable and sustainable lubrication mechanism.