Tribological properties of protic ionic liquid and functionalized copper oxide nanoparticles as additives to base oil


  • T. Taaber University of Tartu
  • A. E. Enok University of Tartu
  • U. Joost University of Tartu
  • S. Oras University of Tartu
  • M. Järvekülg University of Tartu
  • R. Lõhmus University of Tartu
  • U. Mäeorg University of Tartu, Institute of Chemistry
  • K. Saal University of Tartu



ionic liquids, tribology, nanoparticles, copper oxide nanoparticles


The aim of the present study was to investigate a novel composite as lubricant additive for metal wear parts, composing of protic ionic liquid and functionalized copper oxide nanoparticle composite. A simple and an easy-to-modify synthesis method for the preparation of thiol cov-ered copper oxide nanoparticles was developed. A long process of optimization of reaction parameters was carried out that resulted in preparing non-agglomerated oil dis-persible copper oxide nanoparticles with an estimated av-erage diameter of 60 nanometers based on SEM measure-ments. Novel protic ionic liquid, which dissolves in oil was synthesized. Lubricant tribological experiments with the standardized four-ball-method were conducted with 15 kg. The addition of 3% ionic liquid and 0.5% copper oxide nanoparticles to base oil reduced the wear up to 35% com-pared to base oil without any additives, while 1% of protic IL reduced wear up to 47%. In addition, the novel type lubricant additive has many advantages and can also widen the range of applications, e.g. wider temperature range and preserved functionality at harsh conditions where oil-based lubricants fail.