Macroscale superdurable superlubricity achieved in lubricant oil via operando tribochemical formation of fullerene-like carbon

Abstract

Friction and wear are ubiquitous in moving mechanical assemblies, causing energy and equipment loss and producing harmful emissions. Mitigation efforts have long relied on oil-based lubricants, but challenges remain in achieving concurrent ultralow friction and wear without oil additives. Here, we demonstrate that a dual-phase TiB2-MoS2 film lubricated by oil without additives exhibits superdurable superlubricity characterized by a vanishingly small friction coefficient (0.007) and ultralow wear rate (10−9 mm3N−1m−1) maintained in lubricants over an unprecedentedly long sliding distance without performance deterioration. We identify a tribochemical route for the decomposition of oil molecules catalytically activated by the TiB2-MoS2 film, leading to operando formation of fullerene-like carbon that leads to diminished friction. First-principles calculations unveil strong stress responses of a TiB2 structural framework under wear strains, offering insights into the ultralow wear rate. These findings showcase a promising strategy to develop high-performance superlubricating materials that meet stringent conditions for demanding applications.