Tribological properties of oleylamine-modified nickel nanoparticles as lubricating oil additive

In order to improve the friction-reducing and anti-wear abilities of lubricating oil containing nickel nanoparticles as additive, nickel nanoparticles prepared by high energy ion beam evaporation (HEIBE) technique were modified by oleylamine on the surface. The morphology and microstructure of oleylamine-modified nickel nanoparticles showed that oleylamine was successfully attached to the surface of nickel nanoparticles. The friction-reducing and anti-wear properties of lubricating oil containing nickel nanoparticles and oleylamine-modified nickel nanoparticles as additive were investigated by four-ball tribometer. The addition of oleylamine-modified nickel nanoparticles into lubricating oil further reduced the friction coefficient and wear scar diameter of the steel balls lubricated by the base oil PAO6 and the engine oil CJ-4. Compared with the pure PAO6 oil, the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by PAO6 oil with the addition of nickel nanoparticles decreased by up to 32.6% and 15.3%, and that lubricated by PAO6 oil with the addition of oleylamine-modifiednickel nanoparticles decreased by up to 48.4% and 20.4%, respectively. Besides, the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by CJ-4 engine oil with the addition of 0.1 wt% of oleylamine-modified nickel nanoparticles decreased by 38.1% and 18.3% in comparison with the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by pure CJ-4 engine oil.