In-situ preparation of ionic liquid lubricating additives for enhanced lubrication performance in titanium alloys: Experimental and molecular dynamics simulations

Abstract

This work explores the lubrication properties of aqueous solutions containing ionic liquids in contact with cemented carbide and titanium alloy, focusing on the influence of alkyl chain structure. Surface morphology and chemical elements of the worn surface were analyzed using SEM and XPS, and the corrosion resistance was tested. The findings indicate that lubricants containing ionic liquids with unsaturated long alkyl chains can achieve a 70% reduction in friction coefficient and a 91% decrease in wear volume. Ionic liquids in aqueous solutions can effectively prevent the corrosion of gray cast iron by water molecules. Also, quantum chemical calculations and molecular dynamics simulations suggest that anions with unsaturated long alkyl chains exhibit a low energy gap and strong adsorption to the titanium alloy substrate. This implies that to react thermochemically with the metal substrate when it is heated by friction, creating a protective tribofilm. In the torque tests, lubricants containing ionic liquids with unsaturated long alkyl chains penetrate the gaps between the tap and titanium alloy more easily, adsorb onto the contact interface, and form a protective film, resulting in lower torque values. This suggests that the lubricant can serve as a high-performance potential additive in metalworking fluids.