Experimental investigation of the tribological behavior of lubricants with additive containing copper nanoparticles

Friction coefficient and wear tests were conducted to evaluate the tribological behavior of a copper-nanoparticle based additive in mineral and synthetic base oils.
- The polarity of base oil is determinative to the additive performance: Nano-additive was not suitable as friction modifier nor as antiwear agent in polar compound tested (synthetic ester base oil).
- The behavior as friction modifier of the nano-additive is influenced by load, temperature and/or sliding speed.
- Copper nano-additive produced lower mean friction coefficient when added to mineral oil, besides a remarkable reduction in wear.
- The nano-additive efficiency, as antiwear agent in mineral base oil, increases with the reduction of the contact pressure.

This study investigates the tribological behavior of mineral and synthetic ester base oils additivated with copper nanoparticles. The additive was dispersed at 0.3% and 3.0%wt. in each base oil. The friction and wear tests were performed using a tribometer with pin-on-disk and four-ball configuration. Tests with the formulations with and without the nano-additive were carried under different conditions of contact pressures, sliding speeds and oil bath temperatures. The results indicate that the additive, at both concentrations, is not suitable for the application as friction modifier nor as antiwear agent in synthetic polar oil. Furthermore, the results show that the nano-additive in mineral oil reduced the friction coefficient and improved antiwear characteristics at both concentrations tested, especially at 0.3%wt.