Abstract

Near-zero wear on engineering steel surfaces is a promising solution to extend the service life of mechanical equipment. However, most existing strategies offer only limited low wear under particular conditions and friction pairs. To address this, we design a polymer-based proton ionic liquid (PPILs) lubricant, leveraging the proton exchange between polyethylenimine, which is rich in active nitrogen groups, and bis(2-ethylhexyl) phosphate. The results indicate that under high Hertzian contact pressure (2.15 GPa), the friction coefficient of PPILs is similar to 0.08, and the wear rate of the steel disk is as low as 1.46 x 10(-10) mm(3)N1-m(-1). Even in multiple environments (long-term friction or high frequency), PPILs continue to exhibit durable near-zero wear behavior. It is related to the combined effects of adsorption films, tribochemical films, and hydrodynamic effects. Moreover, the PPILs were combined with polyol aqueous solutions to create a superlubrication system (mu = 0.007) with an ultrashort running-in period (<3 s) under Si3N4/glass friction pairs, thereby enriching the research on superlubrication materials. This study addresses the existing limitations of ultralow wear on engineering steel surfaces and introduces a new category of polymer-based protic ionic liquid lubricants, significantly expanding the application of ultralow wear materials.

Keywords Plus：SUPERLUBRICITY，MIXTURES，TRIBOLOGY，FRICTION，IRON

Published in  ACS APPLIED MATERIALS & INTERFACES，Volume17；10.1021/acsami.5c11623，SEP 17 2025