The achievement of a superlubricity state with vanishing friction and negligible wear has important applications in minimizing energy dissipation and prolonging the service life of moving mechanical systems. However, the search for a superlubricious oil system applicable to industrial fields remains a big challenge. We demonstrate in this work for the first time that precisely employing polyether modification for silicone oil molecules could induce direct superlubricity and superlow wear for engineering steel tribopairs. Superlubricity originates as the polyether-modified silicone oil could effectively employ the polyether functional group to interact with the friction surfaces, during which a complex tribochemical reaction process could be induced under the catalytic role of friction, where an organic lubricious film mainly composed of carbon, silicon and oxygen elements could be induced to be in-situ formed, which could not only effectively passivate the friction surfaces but also enable the superlubric sliding by virtue of its easy-to-shear nature. Furthermore, iron oxides and chromium oxides could also be confirmed distributed within the tribofilm, desirable for increasing the load-bearing capability of tribofilm and the toughness. Thus, remarkable superlubricity of 0.01 without a running-in combined with superlow wear has been realized at the same time. The results of this work show high promise in promoting the industrial use of oil superlubricity and revolutionizing the development of mechanical systems.

Friction remains as the primary mode of energy dissipation and components wear, and achieving superlubricity shows high promise in energy conservation and lifetime wear protection. The results in this work demonstrate that direct superlubricity combined with superlow wear can be realized for steel/Si₃N₄ contacts on engineering scale when polyhydroxy alcohol solution was selectively modified by amino group. Macroscopic direct superlubricity occurs because 3-amino-1,2-propanediol molecules at the friction interface could be induced to rotate and adsorb vertically on the friction surface, forming in-situ thick and dense molecular films to passivate the asperity contacts. Furthermore, amino modification is also conducive to improving the lubrication state from boundary to mixed lubrication regime by strengthening the intermolecular hydrogen bonding interaction, presenting enhanced load-bearing capability and reduced direct solid asperity contacts. Thus, direct superlow average friction of 0.01 combined with superlow wear are achieved simultaneously. The design principle of direct superlubricity and superlow wear in this work indeed offers an effective strategy to fundamentally improve energy efficiency and provide lifetime wear protection for moving mechanical assemblies.