Insight into remarkable oil superlubricity enabled by polyether-modified silicone oil on engineering steel

The achievement of a superlubric 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 major challenge. In this work, we demonstrate 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 from the fact that polyether-modified silicone oil (PESO) can effectively employ polyether functional groups to interact with friction surfaces, during which a complex tribochemical reaction process can be induced under the catalytic role of friction, where an organic lubricious film composed mainly of carbon, silicon and oxygen can be induced in situ, which can not only effectively passivate friction surfaces but also enable superlubric sliding by virtue of its easy-to-shear nature. Furthermore, iron oxides and chromium oxides could also be confirmed to be distributed within the tribofilm, which is desirable for increasing the load-bearing capability of the tribofilm and toughness. Thus, a remarkable superlubricity of 0.01 without running-in combined with superlow wear was 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.