Optimal lubricating protection and interfacial behavior for titanium alloy surface from phosphorus-based ionic liquids

The poor wear resistance of titanium alloy makes it challenging to develop high-performance lubricating materials. For the characteristic of highly designable structure, ionic liquids (ILs) are the potential lubricants with excellent physicochemical properties and lubricating performance. Herein, three protic phosphorus-based ionic liquids (PPILs) were designed and synthesized with the exploration of their interfacial lubrication behavior and interaction mechanism on the titanium substrate. The as-synthesized IL lubricants exhibit optimal tribological properties on steel-titanium friction pairs even at high load and temperature. The surface analysis showed that IL can form the lubricating protective film on the titanium-based metal surface, effectively reducing the adhesive wear . Combined with surface analysis techniques (SEM, XPS , FIB-TEM and TOF-SIMS), the lubrication mechanism was discussed systematically.