Study On The Preparation And Properties Of Graphene/WS₂ Lithium Complex Grease

As an inevitable problem in modern industry,friction and wear has been paid lot of attention.Effective control of friction and wear can not only save enormous energy,but also elongate the service life of the equipment,so as to improve the economic benefits.As a common lubricant,grease can effectively reduce friction coefficient and prevent material wear.As a representative of high performance grease,lithium complex grease has a wide operating temperature range and a high extreme pressure bearing capacity.It is found that nano particles can greatly improve the performance of lubricating grease when they are added into grease as additives.In this paper,nano graphene(GP)and tungsten disulfide(WS₂)were added as additives into complex lithium grease to study the effect of nano particles on the performance and properties of lubricating grease.The effects of different modifiers,dispersants,dispersant concentration,dispersion methods and dispersion time on the dispersion stability of GP in base oil were studied respectively in this thesis.GP lubricating oil with good dispersing stability was obtained by modificating the GP with oleic acid,using T154 as the dispersant,controlling the mass ratio of T154 to GP at 0.6,dispersing the GP into PAO6 by ultrasonic assisted ball milling for 30min.Then,the GP powder before and after modification was characterized by infrared spectrum,Raman spectrum and SEM,and the dispersion stability of the oil was evaluated by ultraviolet spectrophotometer.The results showed that after surface modification,dispersant dispersion and ultrasonic ball milling,the dispersion stability of GP was greatly improved after modification.In addition,different concentrations of GP base oil was synthesized into complex lithium grease,and the tribological properties of the grease were studied.It was found that GP can improve the antiwear and friction-reduce performance of the grease.When the concentration of GP was 0.2%,the grease owns the best antiwear and friction-reducing performance.In addition,the best dispersion method for WS₂is obtained via the same research method.GP and WS₂were added into the grease as additives at different concentrations and ratios and the effects of compounded additives on the physical and chemical characteristics,friction performances and corrosion resistance of lubricating grease were studied.The results showed that GP and WS₂can significantly improve the anti-wear and friction-reducing performance of the complex lithium grease.When the concentration of the composite additive came to 0.2%,the ratio of GP and WS₂stayed at 1:1,the grease owned the best tribological performance,the wear spot diameter declined by 36.5%,and the friction coefficient decreased by 33.8%.The extreme pressure bearing capacity and corrosion resistance of lubricating grease climbed with the increase of the additive concentration.When the concentration came to 0.5%,the P_Band P_Dvalues reached the maximum,and the corrosion area of the steel sheet in the salt spray test reached the minimum.Finally,the mechanism of GP/WS2 compound additive to improve the tribological properties and salt spray corrosion resistance of lubricating grease was analyzed.