Effect Of Surface Functional Groups And Sizes Of Silica Particles On Tribological Properties In Rapeseed Oil

Nanoparticles as lubricant additives show excellent lubrication performance.Because of the diversity of material structure,morphology,particle size distribution and surface modification groups of nanoparticles,the research results of the mechanism of Nano-Additives are contradictory and difficult to unify.Therefore,in this paper,silica microparticles are used as lubricant additives,.Using the excellent anti-oxidation,anti-friction,and degradable advantages of rapeseed oil,and its excellent dispersibility to silica,The tribological properties of different surface modification groups and a series of silica particles with different particle sizes in rapeseed oil were systematically studied.The main research contents and results are as follows:(1)Tribological properties of silica nanoparticles modified by different functional groups in rapeseed oilCommercial silica nanoparticles with different surface functional groups were used as lubricant additives for rapeseed oil.Tribological properties of silica nanoparticles with methyl,vinyl and epoxy groups were studied by four-ball friction test.The results show that when the content is optimally added,Three kinds of silicas with the same particle size and containing methyl,vinyl and epoxy groups on the surface,which can reduce the friction coefficient by 33.5%,12.97%,9.01%,and the diameter of the wear scar by 17.23% and 8.67%,5.75%.DNS-2 silica with larger particle size and methyl group can reduce the wear spot diameter of rapeseed oil by 29.5%.Quartz crystal microbalance(QCM)was used to study the effect of surface functional groups on the adsorption quality of metal surface.The results showed that the equilibrium adsorption mass of silica nanoparticles with methyl,vinyl and epoxy groups on the same surface increased in turn.When the surface groups are the same,the equilibrium adsorption mass of DNS-2 silica with particle size of 24 nm is larger than that of DNS-3 silica with particle size of 9 nm.Comparing the tribological properties of silica nanoparticles with different functional groups and their adsorption quality on metal surface,it is found that the adsorption quality is proportional to the Tribological properties.(2)Preparation of silica microspheres with different particle sizes and their tribological properties in rapeseed oilThe silica spheres with good sphericity and uniform particle size were prepared by sol-gel method by adjusting the reaction parameters,adding electrolytes and using seed growth method.The diameter of the particles ranged from 30 nm-3.6?m to a wide scale.Five kinds of silica microspheres(100nm,400 nm,600nm,1?m,3?m)were selected to disperse in rapeseed oil.The effect of particle size of additives on the lubrication performance of rapeseed oil in different lubrication zones was studied.The Stribeck lubrication curves of rapeseed oil with different particle sizes of silica showed that in the elastohydrodynamic region,Silicon dioxide shows outstanding antifriction performance,which reduces the friction coefficient by 5.58%-13.6% compared with rapeseed oil.The rheological properties of silicon dioxide with different particle sizes in rapeseed oil showed that there was an optimum particle size for viscosity reduction.At the optimum concentration,the bigger the particle size,the more obvious the viscosity reduction effect of silica on rapeseed oil.Therefore,in the elastohydrodynamic lubrication zone,the larger the particle size,the better the friction reduction performance of silica.silica in the boundary area generally shows outstanding wear resistance,Compared with rapeseed oil,the wear volume of rapeseed oil decreased by 28.3%-37.55%.The results of wear surface analysis show that the smaller the particle size of silica,the easier it is to enter the surface of friction pairs to form friction film,the stronger the ability is,and the better the anti-wear effect is.