Robust Macroscale Superlubricity in Humid Air Via Designing Amorphous DLC/Crystalline TMDs Friction Pair

Superlubricity, a cutting-edge concept, has the potential to drive the Fourth Industrial Revolution giving its near-zero energy consumption, but the challenge is how to achieve it in humid air with chemical activity and at macroscale surfaces with unavoidable defects. Here, a novel principle involving the amorphous/crystalline friction pair based on the cognition that tribochemical interaction sites originate from grain boundary defect locations is proposed to achieve macroscale superlubricity in humid air. The absence of grain boundaries in amorphous diamond-like carbon (DLC) significantly reduces chemical interaction during the sliding process. This is supported by experimental observations of priority oxidation at the grain boundaries. Results indicate DLC versus MoS2 friction pair has weakened chemical interaction and less humid insensitivity compared to the MoS2 versus MoS2 pair, even increasing the contact area. Theoretical simulation suggests that DLC versus MoS2 pair eliminates the cross-linking of friction interlayers induced by the enrichment of H2O molecules at MoS2 defects. The robust superlubricity is achieved for the typical friction pair of DLC versus MoS2 in air (RH <= 25%) at macroscopic contact pressure (1.1 GPa) with friction coefficient in 10-3 magnitude and extra-long anti-wear life (more than 2 x 105 cycles), which is of significance for the industrialization of superlubricity. Here, a novel principle involving the amorphous lubricants/crystalline lubricants friction pair based on the cognition that tribochemical interaction sites originate from grain boundary defect locations is proposed to achieve macroscale superlubricity in humid air. image