Fe/onion-like fullerenes (Fe/OLFs) were synthesized by chemical vapor deposition (CVD) from acetylene with ferrocene as catalyst.Field-emission scanning electron microscopy (FESEM)

high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques were used to characterize the morphologies and microstructures of the Fe/OLFs.The results indicated that the Fe/OLFs were quasi-spherical particles with closed concentric shells.The distance between the shells was approximately 0.349 nm that closely matched the lattice parameter d002 (0.336 nm) of bulk graphite.Furthermore

Fe/OLFs were added to base lubricant and the tribological properties of Fe/OLFs were investigated with a four-ball type tribometer.The tribological results showed that Fe/OLFs as lubricant additives exhibited good friction-reducing ability at different additive concentrations and applied loads.Meanwhile

they could also strikingly improve the load-carrying capacity of base lubricant.The optimum content of Fe/OLFs was 0.02%（mass） for improving the friction-reducing ability of base lubricant

while the maximum reduction of friction coefficient was about 40.8％.Both Fe/OLFs and carbon nanotubes (CNTs) had friction-reducing ability

while the friction reduction of Fe/OLFs was better than CNTs with the same mass fraction and applied load.