Tribological performance of ionic liquids as additives of water-based cutting fluids

Dry machining of aluminum parts has been the most eco-friendly method in an attempt to reduce the use of mineral-based lubricants and other working fluids. The drawbacks of dry machining include an increase of contact temperatures and stresses leading to high values of tool wear and a decrease of the tool life. For this reason, more sustainable lubricants are needed as a middle point between waste generation and tool life. Since 2001, Ionic Liquids (ILs) have attracted interest as high-performance lubricants and lubricant additives. In this work, the lubricating ability of one halogen-containing and two halogen-free ILs used as additives in water has been investigated and compared to a halogen-containing cutting fluid (CF). Tests were performed using a pin-on-disk tribometer for aluminum-tungsten carbide pair. The worn surfaces of the disks and balls were analyzed by optical and scanning electron microscopies, non-contact 3D profilometry and energy dispersive X-ray spectroscopy. It was found that the addition of 1 wt% of one of the halogen-free ILs reduces friction and wear of both aluminum disks and ceramic balls with respect to dry or water-lubricated conditions. In addition, no wear was detected on the ball surface, therefore increasing the tool life compared to the CF.