▎ 摘　　要

Two-dimensional (2D) materials have demonstrated unique friction and antiwear properties unmatched by their bulk (3D) counterparts. A relatively new, large and quickly growing family of two-dimensional early transition metal carbides and nitrides (MXenes) present a great potential in different applications. There is a growing interest in understanding the mechanical and tribological properties of MXenes, however, no report of MXene superlubricity in a solid lubrication process at the macroscale has been presented. Here we investigate the tribological properties of two-dimensional titanium carbide (Ti3C2) MXene deposited on SiO2-coated silicon (Si) substrates subjected to wear by sliding against a diamondlike carbon (DLC)-coated steel ball counterbody using a ball-on-disc tribometer. We have observed that a reduction of the friction coefficient to the superlubric regime (0.0067 +/- 0.0017) can be achieved with Ti3C2 MXene in dry nitrogen environment. Moreover, the addition of graphene to Ti3C2 further reduced the friction by 37.3% and wear by the factor of 2 as compared to Ti3C2 alone, while the superlubricity behavior of the MXene remains unchanged. These results open up new possibilities for exploring the family of MXenes in various tribological applications. (C) 2021 The Authors. Published by Elsevier Ltd.