Nonmonotonic load-dependence of friction during nanoparticle manipulation

The tribological behaviors of nanoparticles (NPs) have received extensive application in the fields of nano-lubrication and ultra-precision manufacturing. The frictional and dynamic behaviors of SiO2 NPs acted with the single asperity were studied on silicon surface utilizing atomic force microscope. Both the static and kinetic friction forces of NPs exhibit an initial decrease followed by an increase with the increasing manipulation load (0 ~ 300 nN). The nonmonotonic load-dependence of friction behavior matches the dynamic transformation of “sliding-rolling-sliding” motion state of the manipulated NPs, which can be predicted by a Double-Hertz model and further confirmed by the nanoindentation marked NPs. This research has a great guiding significance for the regulated dynamic behaviors of NPs in the current three-body abrasive tribology.