Synthesis and tribological behavior of ionic liquid substituted fluoroalkoxycyclophosphazene derivatives in steel-steel contacts

Purpose - The purpose of this paper is to synthesize a series of cyclophosphazene derivatives with better tribological properties. Design/methodology/approach - To improve the adsorptivity to substrate, a series of cyclophosphazene derivatives substituted with ionic liquids were synthesized. The lubricity characteristics of phosphazene derivatives were evaluated on an Optimol SRV IV oscillating friction and wear tester. Scanning electron microscope and X-ray photoelectron spectroscope analyses were conducted to examine the morphology and chemical composition of the wear scars and the possible tribochemical changes involved in the friction process. Findings - Alkoxycyclophosphazene derivatives substituted with ionic liquids synthesized in the present work show better antiwear ability and load-carrying capacity in steel-steel contacts. The density of ion pairs plays an important role on tribological properties. Research limitations/implications - The paper deals with only a limited compounds and steel-steel contacts. The paper works on the subject progressively to explore more combinations for better tribological properties. Practical implications - All the cyclophosphazene derivatives present better tribological performance and could be used as base oils, such as hard disk surface lubricants. Originality/value - Ionic liquids are introduced to cyclophosphazene derivatives in this paper. This is a new method to improve the tribological properties of cyclophosphazene derivatives.