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Friction and wear are the main reasons for decreasing the lifetime of moving mechanical components and causing energy loss. It is desirable to achieve macroscale superlubricity on industrial materials for minimizing friction. Herein, the two-dimensional material black phosphorus (BP) is prepared as an oil-based nanoadditive in oleic acid (OA) and shown to produce macroscale superlubricity at the steel/steel contact under high pressure. Experiments and molecular dynamics simulation reveal that BP quickly captures the carboxylic group and, as a result of the high contact pressure and heat, OA decomposes to release passivating species and recombines to form amorphous carbon giving rise to a composite solid tribofilm with BP. The OA and passivating groups adsorb onto the solid tribofilm to produce the passivating layer, thus resulting in macroscale superlubricity. The findings provide fundamental insight into the nature of tribochemical mechanisms and suggest a new approach to achieve macroscale superlubricity of industrial materials.

Reducing friction and wear in a convenient and economical way has always been desired for industrial production. Here, a carbon-based film with excellent friction-reducing and antiwear abilities was formed in situ from the degradation of poly-α-olefin oil (PAO10) on the friction interfaces of the MoN/Pt coating sliding against the Si 3 N 4 ceramic ball during the rubbing process. The MoN/ Pt coating was prepared on stainless steel by direct current magnetron sputtering, in which an active 10 nm Pt layer grew well on the MoN layer. The MoN/Pt coating, lubricated by trace amounts of 5 mL PAO10 oil, exhibited a super low friction coefficient of 0.042 and an extremely low wear rate of 1.08 × 10 −8 mm 3 (N m) −1 after a long duration of applied friction under a high Hertz contact stress of 1.7 GPa. Raman spectra and transmission electron microscopy images revealed that the carbon-based film was composed of amorphous carbon phase dotted with sporadic Pt, MoO 3 , and SiO 2 crystal phases. Molecular dynamics simulations illustrated that the MoN/Pt coating had catalytic action and resulted in the degradation of PAO10 during the rubbing process, which corresponded to the formation of the amorphous carbon-based film on the wear surfaces.

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