| The lubricant used in the field of metal plastic forming not only needs excellent anti-friction and anti-wear performance,but also must be a green,environment-friendly and pollution-free product.The combination of the excellent lubrication and anti-wear properties of graphene and the water-based green and environmentally friendly lubricant meets the requirements of modern technology.Phosphorus saponified lubrication,the most widely used in the market,is complicated,polluting,energy-consuming and costly,so it is urgent to develop a new lubricants.As a new nano material,graphene has the advantages of high mechanical strength and good self-lubrication performance,so it is very suitable to be used as the main abrasive of lubricant.In this paper,the tribological properties of graphene as a lubricant were studied.With natural graphite as the main material,reduced graphene oxide was prepared by REDOX method.Modified graphene was synthesized by sodium dodecylbenzene sulfonate?SDBS?.Raman spectroscopy and Fourier transform infrared spectroscopy were used to characterize and analyze the functional groups and microstructure of the graphene toner.It was found that sodium dodecylbenzene sulfonate was grafted on the graphene.The maximum stable dispersion concentration was obtained by dispersion test as 3mg/m L,and graphene lubricant was prepared by using the independently developed lubricant formula.It was found that 3mg/m L graphene lubricant could be stable and dispersed for 144 hours.The graphene sample was coated by graphene lubricant,and the thickness of the graphene lubricant was measured by a step meter to be about 4-7?m.Through ball-on-disc friction test and ring compression test,the tribological properties of graphene lubricant in mechanical round-trip motion and plastic forming motion were studied.It was found that 3mg/m L graphene lubricant had the best lubrication performance,with a coefficient of friction of 0.156,and the coefficient of friction and wear rate were significantly lower than dry friction.The wear scars were observed by SEM and EDAX.Characterization showed that the graphene lubricant not only had excellent anti-friction and anti-wear properties,but also had certain antioxidant capacity.Finally,the improved adhesion theory was used to calculate that the anti-wear strength of the metal was increased from 1.52×104 kg·mm-2 to9.39×104 kg·mm-2 after adding 3 mg/m L graphene lubricant.The excellent mechanical performance of graphene is make up the low mechanical strength,poor wear resistance of macromolecule.Therefore,the tribological characteristics of graphene doped PTFE composites were studied by ball-on-disk friction test.The coefficient of friction of PTFE samples is 0.310,the coefficient of friction of graphene is0.173,the coefficient of friction of 3%composite material is 0.109,which is the lowest in five groups of test.The samples with the lowest wear rate were 5%composites,which decreased by 55.5%compared with the PTFE samples with the highest wear rate.Scanning electron microscope?SEM?,energy dispersive analyzer?EDAX?and 3D profile were used to observe the morphological features and microstructure of the graphene,PTFE and composite materials.It was found that the graphene doped PTFE composites could combine the advantages of the two organically and develop better lubrication properties than the graphene and PTFE.Finally,the anti-wear strength of PTFE can be calculated as5.07×104 kg·mm-2.After adding 5%graphene,the anti-wear strength was increased to3.5×105 kg·mm-2,which greatly improved the anti-wear strength. |
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