Study On The Preparation Of Functional Crumpled Graphene Balls And Tribological Properties In Lubricating Oils

As a new type of nanomaterial,graphene has quite a lot of excellent properties,such as self-lubricity,thermal stability,high mechanical properties,etc.However,graphene is easy to agglomerate in lubricating oils and difficult to disperse stably,which limits its effective utilization.Therefore,functional modification and micro-regulation of graphene are needed to improve its utilization rate.The main research contents of this paper are as follows:1.Preparation and tribological properties of chemically crumpled graphene balls.The GO solution prepared by modified Hummer was spray dried as the original solution,and the crumpled graphene balls?CGB?were successfully prepared,and then modified by oleic acid and stearic acid.Modified crumpled graphene balls?MCGB?were prepared by condensation reaction between G?OH and?COOH to form stable covalent bonds.Its structure and morphology were characterized by SEM,XRD and FTIR.The results showed that the CGB was an irregular crumpled particle with a diameter of 10²0?m,a small folding degree of surface of crumpled graphene balls and a thick structure of crumpled graphene balls.After natural placement for one month,MCGB still has good dispersion in the base oil,proving that MCGB has weak interspherical van der Waals force and can inhibit interparticle agglomeration to some extent.Adding 0.01%of MPCGB to base oil has the best anti-friction effect,and its friction coefficient,wearing capacity and wear scar diameter are reduced by 2.08%?16.18%and11.48%,respectively.2.Preparation and tribological properties of porous crumpled graphene balls.In order to increase the folding degree of crumpled graphene balls,reducing the thickness of the layer structure of crumpled graphene balls,improve the tribological performance of crumpled graphene balls in base oil,we prepared a uniform mixture of GO and pore-forming agent?NH₄?₂CO₃ at mass ratios of 1:2,1:5,1:10 and 1:20,and then spray dried it to obtain a series of porous crumpled graphene balls?PCGB?powder,which was modified by oleic acid and stearic acid.Its structure and performance were characterized by SEM,XRD,FTIR,pressure test and tribological test.The results show that PCGB is a porous ball structure with particle size of 5¹0?m,and PCGB is a hollow porous ball rather than a solid ball.When GO:?NH₄?₂CO₃=1:2,the crumpled structure is fragile and the particle size of the folded structure formed under pressure is the smallest.Adding 0.01%of 1:2 MPCGB to base oil has the best anti-friction effect,and its friction coefficient,wearing capacity and wear scar diameter are reduced by 11.18%,18.82%and 13.79%,respectively.3.Preparation and tribological properties of nanometer magnesium silicate hydroxide/crumpled graphene ball composites.Magnesium silicate hydroxide?MSH?nanoparticles with high hardness were loaded on the surface of crumpled graphene ball by liquid phase stripping method,which is another method to increase the folding degree on the surface of crumpled graphene balls and reduce the structural thickness of crumpled graphene ball.The GO crumpled graphene ball were mixed with MSH at different mass ratios,and then the MSH/GO was successfully prepared by liquid phase ultrasonic stripping,and modified by oleic acid and stearic acid.Its structure and properties were characterized by SEM,XRD,FTIR and friction test.The results showed that the high-frequency collision between MSH and crumpled graphene balls could be realized by high-intensity ultrasound,and the folded spherical structure of crumpled graphene ball was opened to form a thin and highly crumpled graphene structure.The tribological test results show that:when the mass ratio of GO and MSH is 5:1,the friction coefficient is lower than that of pure MSH base oil and pure MGO base oil,showing better synergistic anti-friction effect;Adding 0.005%5:1 ML-MSH/GO to the base oil has the best anti-friction effect,and its friction coefficient,wearing capacity and wear scar diameter are reduced by 25.43%,22.06%and 16.72%,respectively.