| In recent years,anti-wear and anti-friction technologies have developed rapidly.Traditional lubricants have begun to show their limitations under the condition of micro-scale friction.In order to better study the micro-dynamic process of the friction interface,establish physical models and micro-tribological phenomena.Analysis method,nanotribology came into being.Adding nanoparticles to lubricating oil has become an important means to improve the anti-wear and anti-friction properties of lubricating oils.It can repair the worn surface through the synergy between the particles and play a self-lubricating effect.In this paper,graphene is selected as a lubricant additive,and the factors affecting the dispersion stability,friction and wear performance and anti-wear and friction reduction laws of graphene lubricants are studied.The main conclusions are as follows:(1)Comparative analysis of structure and disorder of graphene sheets obtained by two preparation methods was carried out to ensure that the materials used in the test meet the requirements;The oleic acid-stearic acid mixture is used to modify the surface of graphene and disperse it in lubricating oil to obtain graphene lubricating oil.The absorption value is measured by the natural sedimentation method and spectrophotometric method,and the result is as follows: The precipitation of graphene lubricating oil by chemical method is obviously serious,while the color of graphene lubricating oil by physical method is basically stable;the curves of different lubricating oils in the absorbance range(300-800nm)show a consistent change trend,that is,with the sedimentation time As it increases,the absorbance gradually decreases.(2)A four-ball friction and wear test machine was used to design an anti-wear and anti-friction test,and the influence of two different preparation processes on the tribological properties of graphene lubricants was studied.The results show that the modified physical graphene lubricating oil has better anti-wear and anti-friction properties,and obtains a lower friction coefficient,and the average friction coefficient is reduced by about 26%;the microscopic morphology of the worn surface is measured by electron microscope and energy spectrometer And the composition structure was characterized and analyzed.After the modification,the diameter of the wear scar on the surface of the steel ball under the action of the physical method of graphene lubricating oil was reduced by 8.0% compared with the diameter of the wear scar on the surface of the steel ball under the action of the pure base oil.The graphene particles can be stably adsorbed on the friction surface,which improves the wear resistance of the friction pair surface.(3)Based on the graphene lubricating oil of the physical liquid phase exfoliation method,the graphene lubricating oil of 0.030wt%,0.035wt%,0.040wt%,0.050wt% was prepared,and they were carried out at room temperature,100℃,150℃,Data processing and analysis were carried out for the friction test under 200℃ temperature and 392 N and470N load.In comparison,the graphene lubricant with a concentration of 0.035wt% has a better anti-wear and anti-friction effect.At this concentration,the friction coefficient is reduced by 45.1%,and the wear scar diameter is reduced by 50.4%.Observe the surface of the sample after wear.Result: When the mass ratio of nanoparticles is too high,it will cause serious agglomeration.The agglomerated graphene particles scratch the surface of the steel ball,resulting in an increase in the friction coefficient;the higher the temperature,the greater the friction coefficient and the larger the wear scar diameter.The larger the wear scar,the wider the wear scar,and the accumulated graphene aggregates on the wear surface;this is because the load increases,the contact surface stress increases,and the friction force increases,resulting in an increase in the friction coefficient. |
