关键词: 磨削, 微量润滑, 纳米流体, 球形纳米颗粒, 摩擦学机制

Abstract: This paper aimed to study the anti-friction and anti-wear mechanism and to further reveal 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 results 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 interfaces, 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, resulting 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 polishing, occur on the grinding interfaces. The polishing scratches may enlarge the wet areas of ionic liquid, and hence may reduce the contact areas between abrasive grain and workpiece. The rolling behavior of alumina nanoparticle that moves like rolling balls may transform the sliding friction between abrasive grain and workpiece into rolling friction. Tangential grinding force is therefore reduced by 6.6 percent compared with MQL grinding.

Key words: grinding, minimum quantity lubrication(MQL), nanofluid, spherical nanoparticle, tribological mechanism