Abstract

Polyurea grease with excellent high-temperature tolerance and lubrication properties is expected to satisfy the service requirements of advanced equipment in high-temperature harsh conditions, but it is still restricted by the insufficient high-temperature anti-wear performance. Currently, TCP as commercial additive exhibits good hightemperature anti-wear properties, which requires 3% or higher addition amount, and it also has obvious neurotoxicity. Two novel diphenyl phosphate ionic liquids (ILs) were reported in this study, and their rheological behavior and high-temperature frictional properties were systematically evaluated in polyurea grease. Rheological analyses confirmed that the addition of ILs preserved the physicochemical integrity of base grease, while markedly improving its thixotropic characteristics. Tribological assessments demonstrated that even at a minimal additive content of 0.2% could also reduce the friction coefficient of base grease by 37.5% and the wear scar diameter by 66%, which was comparable to 15 times the addition amount of TCP (3%). Furthermore, Surface analysis employing scanning electron microscopy and other methods demonstrated that the excellent anti-wear and friction-reducing performances of ILs was attributed to the frictional chemical reaction films of iron phosphate, organic substances, and IL adsorption layers. The present study proposes solutions and technical routes for significantly diminishing or substituting TCP as a high-temperature lubricating additives.

Keywords Plus: TRIBOLOGICAL PROPERTIES，STEEL/STEEL CONTACTS，ANTIWEAR PERFORMANCE，POLYUREA GREASE，LUBRICATION，MECHANISM

Published in TRIBOLOGY INTERNATIONAL，Volume225；10.1016/j.triboint.2026.112389，JAN 2027