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

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.