Amino acid-based ionic liquids as water-ethylene glycol additives towards superior lubricity and corrosion resistance

Two novel amino acid-based ionic liquids (AAILs) were synthesized and their tribological properties as water-ethylene glycol (W-EG) lubricant additives were investigated. The addition of 1 wt% of both AAILs to W-EG can significantly enhance the anti-corrosion, friction-reducing and anti-wear properties of the lubricants. Compared to W-EG, the coefficient of friction and wear volume are reduced by about 50% and 75%, respectively. The physical adsorption film and the tribochemical reaction film derived from AAILs collectively establish a protective barrier at the friction interface, endowing the lubricants with superior lubricity and load-carrying capacity. These two sulfur-free and halogen-free AAILs are promising for application in metal working fluids and hydraulic fluids.