Effect Of WS₂ And Copper Nano-additives On Tribological Properties Of Vegetable Oil

Good lubrication plays a vital role in the normal operation of marine machinery and equipment,but mineral-based lubricants cause great damage to the environment during use.Vegetable oil has the advantages of environmental protection and renewable,but pure natural vegetable oil can not meet the requirements of actual working conditions,and must be combined with lubricating oil additives.The oxidized rapeseed oil has the advantages of good oxidation resistance,high viscosity index,good bearing capacity and anti-wear performance,etc.Therefore,the effect of WS2 and copper compound nanoparticle additives on the tribological properties of oxidized rapeseed oil is studied,providing theoretical basis for applied research of green lubricants.The main research work and achievements are as follows:(1)WS2 of micron scale was prepared by thermal decomposition method,and nano-scale WS2 was obtained by high-energy ball grinding.Nano-copper was prepared by liquid phase reduction method.The phase composition and particle size distribution of the nanoparticles were detected and analyzed.(2)The dispersing effect of oleylamine,oleic acid,Span-80,Peregal-O and Tween-80 modified nano-additives in oxidized rapeseed oil was compared by visible spectrophotometer.The results of absorbance and transmittance show that oleylamine has the best surface modification effect on the compound nanoparticles,because the strong oleophilicity of oleylamine makes the hydrocarbon chain in the molecule form a steric hindrance in oil.Secondly,the amine group on the molecular chain of oleylamine has extremely high chemical activity and can be firmly bonded to the surface of the particles.Two factors makes the compound nanoparticles exhibit excellent dispersion effect in oxidized rapeseed oil.(3)According to the experimental results of four-ball friction and wear test of single nanoparticles in oxidized rapeseed oil,the range of orthogonal experimental parameters is refined;By comparing the friction coefficient and spot diameter obtained from the orthogonal test,the optimal combination was obtained as follows:The amount of the addition was 0.9%,the ratio of nano WS2 to copper was 5:1,and the ratio of surfactant to compounded nanoparticles was 0.75:1.Compared with oxidized rapeseed oil,the friction coefficient of the compound nano-additive lubricating oil was reduced by 73.2%,and the wear spot diameter was reduced by 44.9%.(4)The tribological properties of the oxidized rapeseed oil,Great Wall CD40 lubricating oil and compound nanoparticle additive lubricating oil were compared by a reciprocating friction and wear tester.The experimental results show that the friction coefficient and wear amount of the cylinder liner sample lubricated by the compounded nanoparticle additive lubricating oil are better than those of the oxidized rapeseed oil and the Great Wall CD40 lubricating oil.The results of 3D confocal microscopy and SEM showed that the surface of the cylinder liner sample with the compound nano-additive lubricating oil was thinner and shallower than the cylinder liner sample of the oxidized rapeseed oil and Great Wall CD40 lubricating oil.According to the energy spectrum scanning results of the lubricating oil insoluble matter,the compound nano-additive lubricating oil had the spherical nano-WS2 and copper particles,but the other two kinds of lubricating oils did't have.It is speculated that the nanoparticles act to improve the surface flatness and work as the similar "microballs" between the friction pairs,effectively improving the working conditions of the friction pair,thereby improving the antiwear and antifriction properties of the oxidized rapeseed oil.