Macroscale Superlubrication Achieved with Shear-Thinning Semisolid Lubricants.

Abstract

Macrosuperlubric materials are pivotal for reducing friction and wear in engineering applications. However, current solid superlubricants require intricate fabrication and specific conditions (e.g., vacuum or inert atmospheres), while liquid superlubricants are prone to creep, leakage, and corrosion. Here, a novel semisolid subnanometer nanowire (SNW) superlubrication material based on the shear-thinning effect is introduced to overcome these challenges. The SNWs achieve an exceptionally low friction coefficient (0.008-0.009) with silicon nitride (Si3N4) and polytetrafluoroethylene (PTFE) tribo-pairs, demonstrating a brief running-in period (≈39 s) and stable superlubrication over extended friction (12 h, >120000 cycles). The combination of the shear-thinning network structure mechanism, the adsorption membrane mechanism, and hydrodynamic effects provides a synergistic effect, playing a crucial role in achieving superlubricity. Additionally, SNWs can be combined with various base oils to create semisolid gel lubricants with superlubricating properties. This innovative approach addresses the limitations of current superlubrication systems and introduces a new category of semisolid gel lubricants, significantly expanding the applications of superlubrication materials.