Molecular Dynamics Study on Tribological Mechanism of Spherical Nanoparticles on Nickel-based Alloy Grinding Interfaces under Nanofluid MQL
This paper aimed to study the anti-friction and anti-wear mechanism and to further re-veal the formation mechanism of lubrication film generated by nanofluid on the grinding interfaces through molecular dynamics simulations.1-butyl-3-methylimidazolium tetrafluoroborate([BMIM]BF4 ionic liquid)was used as the base fluid of nanofluid.And spherical nanoparticles made of alumina and copper were taken as representatives of high-and low-hardness nanoparticles respectively.The re-sults show that boundary lubrication layer is formed on the grinding interfaces in NMQL grinding of nickel-based alloy.Copper nanoparticle occurs a series of tribological behaviors on the grinding inter-faces,such as compression,shear,spread and separation,because of the far lower hardness than that of abrasive grains and nickel-based alloy workpiece.A layer of solid lubricating film was finally formed by copper nanoparticle,which may reduce the contact areas between abrasive grain and workpiece,re-sulting in lowered tangential grinding force by 4.6 percent compared with MQL grinding.Alumina nanoparticle maintains the initial spherical nanostructure during grinding due to their higher hardness than that of nickel-based alloy workpiece.Three tribological behaviors,i.e.sliding,rolling and polis-hing,occur on the grinding interfaces.The polishing scratches may enlarge the wet areas of ionic liq-uid,and hence may reduce the contact areas between abrasive grain and workpiece.The rolling behav-ior of alumina nanoparticle that moves like rolling balls may transform the sliding friction between ab-rasive grain and workpiece into rolling friction.Tangential grinding force is therefore reduced by 6.6 percent compared with MQL grinding.
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