Tribological and rheological properties of nanorods–Al2O3 as additives in grease

In this paper, the tribological and rheological behaviors of nanorods–Al 2 O 3 as an additive in lithium grease at different concentrations were investigated. The morphology of the additive was determined. The improvement in the rheological properties after adding the nanorods was studied and illustrated by measuring the wear of the tested surfaces. The results showed that nanorods–Al 2 O 3 can greatly improve the lubricating effect of grease. The grease with a 0.3 wt% content of nanorods–Al 2 O 3 exhibited the lowest average friction coefficient and wear scar diameter. The worn steel surface was smooth and showed few furrows and grooves. Moreover, a correlation was found between the tribological and rheological properties of lithium grease. By increasing the temperature continuously, a chemical protective film was produced leading to the reduction in the friction coefficient of grease.