Probing the tribofilm of ionic liquid on nickel-based interface at high temperature with high lubricity

Four novel ionic liquids (ILs) were synthesized and used as pure lubricants for nickel-based metal friction pairs. Compared with the control samples PAO10 and L-P104, the differences in the physical and chemical properties and tribological behavior were explored, and the improvement in lubricating efficiency was obvious. The results reveal that the properties of the synthesized ILs have a molecular structure activity relationship. The rigid structure and active elements N and P in the molecular structure are beneficial for improving the tribological performance of IL lubricants. In contrast to the single adsorption effect on traditional iron-based metals, the nickel-based metal surface forms a thick nickel carbon oxide layer with an IL under the action of friction heat. The tribochemical reaction film formed on the surface synchronously resulted in better antifriction performance and wear- resistance at high temperatures. • Four new types of ionic liquids were synthesized and used as pure lubricants for nickel-based metals. • The IL lubricants shows excellent compatibility on Inconel 690 alloy friction pair. • Two kinds of film structures formed on the surface of nickel base contributes greatly to its lubricity.