Research On Antifriction Test Of Graphene Additive In Lubrication Of Speed Bearing Materials

A large amount of friction heat is generated inside the bearing when the high-speed motorized spindle bearing rotates at high speed,which will affect the high-speed performance of the bearing.Good bearing lubrication can reduce thermal deformation and heat which is generated by friction.In recent years,the research on improving the performance of lubricating oil by nanomaterial additive has been rapidly developed.In particular,graphene is widely used as a lubricating oil additive because of its antifriction mechanism.It is very meaningful for improving bearing life and reducing temperature rise of ceramic bearing to put graphene in lubricating oil as additive.In this thesis,GCrl5/Si3N4 and Si3N4/Si3N4 friction pairs were used to simulate ceramic bearings.Two basic lubricating oil with different viscosities were selected and graphene and graphene oxide were added respectively to explore the tribological properties of GCrl5/Si3N4 and Si3N4/Si3N4 sliding pairs.The effect of graphene as a lubricating oil additive on the lubrication and cooling performance of GCr15/Si3N4 and Si3N4/Si3N4 friction pairs were investigated by using an Rtec MFT5000 friction and wear testing machine.The friction coefficient was automatically recorded by the friction and wear testing machine.The temperature rise at the site of friction was acquired by a temperature-rise detection system.The surface of the wear mark was characterized by scanning electron microscopy and Raman spectroscopy.The width of the wear mark was characterized by viadigital 3D microscopy.The depth of the wear mark was characterized by the OLS4100 3D laser measuring microscope.Experiments were carried out on the GCrl5/Si3N4 friction pair when graphene oxide was used as a lubricant additive.The study showed that the average friction coefficient of the friction pair was reduced by 67.37%when the optimal lubrication parameters were selected(speed was 2500 r/min,load was 80 N,graphene oxide quality score was 0.15%).The temperature rise of the friction pair was reduced by 56.22%when the optimal cooling parameters were selected(speed was 2000 r/min,load was 80 N,and graphene oxide quality score was 0.15%).Experiments were carried out on the Si3N4/Si3N4 friction pair when graphene was used as a lubricant additive.The study showed that the average friction coefficient of the friction pair was reduced by 76.33%when the optimal lubrication parameters were selected(the speed was 3000 r/min,the load was 40 N,the graphene quality score was 0.1%).The temperature rise of the friction pair was reduced by 19.76%when the optimal cooling parameters were selected(speed is 500 r/min,load is 140 N,graphene quality score is 0.05%).The results of this study showed that the tribological properties and cooling properties of GCr15/Si3N4 and Si3N4/Si3N4 friction pairs have been significantly improved after the addition of graphene into the lubricating oil,which attributed to the formation of a lubricating protective film between the friction pairs.The decrease in temperature rise was attributed to the high thermal conductivity and large specific surface area of graphene.