Preparation And Tribological Properties Of Nano Serpentine As Lubricating Oil Additive

The performance of the lubricating oil directly affects the working condition of the ship propulsion equipment.With the development of nanotechnology,nano particles have shown excellent performance as lubricating oil additives.The main component of the serpentine is Mg6(Si4O10)(OH)8,and the special layered structure makes it have good antifriction and antiwear properties.Considering there are many impurities in the natural mineral,this paper also prepared serpentine nano powder by chemical synthesis method.The tribological properties of both natural and synthesized powders as lubricating oil additives were investigated,and the friction modifier was selected to promote the tribological properties of the serpentine powder.The research has shown good theoretical and application value.In the research of this paper,the natural serpentine powder was prepared from natural mineral by mechanical crushing method,and the manmade nano powder was prepared from talc and MgO as raw materials by high-temperature hydrothermal synthetic method.The nanometer laser particle size analyzer,TEM and XRD were used to characterize the particle size distribution,micro morphology and phase composition of the powders.The results showed that the synthetic sepentine powder,which main ingredient is hydroxyl magnesium silicate,has small particle size and much narrow distribution of concentration,and shows one-dimensional hollow tubular structure in micro scale;while the natural serpentine powder shows solid sheet micro-structure,and the particle size and distribution of concentration is larger,in addition,there are impurities in the natural serpentine.Optimizing the addition ratio and modification time of surface modifier through the experiment.Explore the effects of ultrasonic time on the dispersion of nanoparticles in base oil.Evaluate the suspension and dispersion through centrifuge settlement experiment and visible spectrophotometer.The best modification scheme was used to modify the surface of serpentine powder.The tribological properties of natural serpentine nanopowders and synthetic serpentine nanopowders as lubricant additives were investigated by four ball long grinding test and pin disc friction and wear test.Friction modifier MoDTC was added to improve the antifriction and antiwear properties of serpentine.The results show that,compared to the base oil,the lubricating oil containing 1%synthesized serpentine nano powder has the best antifriction and antiwear properties,the friction coefficient of four ball and pin disc coefficient decrease by 60.34%and 40.48%,wear spot diameter has 57.1%decrease,the abrasion loss of disc reduced 40.48%.The best antifriction and antiwear properties can be achieved by using lubricating oil with 0.3%MoDTC and 1%serpentine powder.Simulated the pressure distribution on the surface of friction pairs through Ansys-Fluent software.Disscussing the mechanism of the repair layer formed by the serpentine powder on the friction surface.In the grooves and pits of the surface of the friction pairs,the aggregation of nanoscale powders in the low pressure region will be formed to repair the friction surface.