Study On Tribological Properties And Design Of Nano Molybdenum Disulfide As Lubricant Additive Based On Hydrothermal Synthesis Method

Friction and wear are the main causes of the loss of energy and materials.The energy consumption on friction and wear is 30%-50%of the world’s industrial energy consumption.Reducing the energy loss caused by friction and wear is imminent.In response to the spirit of conference that 13th Five-Year Plan proposed to energy-saving emission reduction as an important breakthrough of optimizing economic structure,promoting green recycling low-carbon development and accelerating the construction of ecological civilization,the development and research of green lubricating oil are remarkably imperative.Nano-molybdenum disulfide(MoS2)is one of great choices as green lubricant additive owing to its excellent anti-wear capacity and photocatalytic performance.In this paper,coral-like nano-MoS2 was prepared via hydrothermal synthesis method.The effect of preparation temperature on the morphology of nanoparticles was studied,and the preparation processes were optimized by surface modification of CTAB,annealing treatment and composited GO.It can be confirmed by SEM,XRD,FTIR and TGA that the morphology and physicochemical properties of MoS2 have been improved.Especially,CTAB not only optimized the morphology and particle size of coral-like nano-MoS2,but also significantly improved its stability and dispersion in liquid paraffin(LP).The friction properties of coral-like nano-MoS2 as additives in liquid paraffin were tested based on four-ball method.The results showed that all nano-MoS2 present excellent tribological performance,and the optimum proportions in LP are 0.4 wt%.By analyzing and summarizing their lubrication mechanism,mainly reasons were concluded:Firstly,the unique loose coral-like structure under shearing force easily stripped into nanosheets to formate in the lubrication system of coexistence of sliding and rolling between the frictional pairs.Secondly,nano-MoS2 had a slight tribochemical reaction between the base oil and metal planel,which contributed to the formation of a stable lubricating oil film.Thirdly,the agglomeration phenomenon and dispersibility in the oil of nano-MoS2 have greatly improved.In addition,based on Lambert-Beer’s law,the photodegradation of waste LP performance of coral-like nano-MoS2 before and after lubrication were investigated by photocatalytic test scheme using n-hexane as solvent.The results showed that coral-like nano-MoS2 has good photodegradation property for LP.Under the experimental conditions,25 mg of CM-MoS2 degraded about 89%of liquid paraffin in 24h,which attributed to that nano-MoS2 having large specific surface area,narrow band gap and high utilization rate of UV-vis can improve the degradation efficiency of LP.Also,the coral-like nano-MoS2 did not degrade the lubricating oil in the blackness,while friction process crushed nano-particles to increase the specific surface area so that promote its photocatalytic performance.This is important for the development of green lubricating oil nano additives for biodegradable lubricants.