Macroscale Robust Superlubricity on Metallic NbB₂

Abstract

Robust superlubricity (RSL), defined by concurrent superlow friction and wear, holds great promise for reducing material and energy loss in vast industrial and technological operations. Despite recent advances, challenges remain in finding materials that exhibit RSL on macrolength and time scales and possess vigorous electrical conduction ability. Here, the discovery of RSL is reported on hydrated NbB2 films that exhibit vanishingly small coefficient of friction (0.001–0.006) and superlow wear rate (≈10−17 m3 N−1 m−1) on large length scales reaching millimeter range and prolonged time scales lasting through extensive loading durations. Moreover, the measured low resistivity (≈10−6 Ω m) of the synthesized NbB2 film indicates ample capability for electrical conduction, extending macroscale RSL to hitherto largely untapped metallic materials. Pertinent microscopic mechanisms are elucidated by deciphering the intricate load‐driven chemical reactions that generate and sustain the observed superlubricating state and assessing the strong stress responses under diverse strains that produce the superior durability.

Niobium Boride/Graphene Directing High-Performance Lithium–Sulfur Batteries Derived from Favorable Surface Passivation

“…To corroborate the above bonding assignments based on the XPS spectra, we have further performed Raman measurements of NbB 2 (Figure c). The signals of both Nb–O (255 and 463 cm –1 ) and B–O (628 and 978 cm –1 ) , can be clearly observed, indicating oxidation of the NbB 2 surface that is exposed to ambient air. Furthermore, we conduct micro-Raman mapping at constants of 255 cm –1 (Nb–O) and 628 cm –1 (B–O), suggesting a uniform distribution of oxygen-containing bonds (Figure d,e).…”

“…The specifics of the DFT calculations can be found in Supporting Information. The electron density difference was calculated using MULTIWFN, , and the isovalues of the electron density difference were visualized with VMD software . The graphene and NbB 2 surfaces were simulated using slab models with 4 × 7 (17.04 × 17.22 Å) and 3 × 5 (16.17 × 15.56 Å) surface unit cell periodicities, respectively.…”

Accelerating Macroscale Superlubricity through Carbon Quantum Dots on Engineering Steel Surfaces

“…Unfortunately, the realization of most solid superlubricity usually requires strict conditions, such as perfect crystal quality, vacuum or inert atmosphere, and complex surface structures. [19][20][21][22] Liquid superlubricity is more achievable than solid superlubricity under environmental conditions, making it a promising option for practical engineering applications. [16,23,24] Various liquid lubricants, such as ionic liquids, [25] polymer brushes, [26] multi-alcohol solutions, [27,28] and aqueous solutions of acids, [29,30] have demonstrated remarkable superlubricity properties.…”