Tribological assessment of vegetable oil based CeO2/CuO hybrid nano-lubricant

Vegetable oil based lubricants attract much attention nowadays due to their excellent boundary lubrication performance and biodegradability. Coconut oil is a vegetable oil with excellent lubricating properties which provides low friction coefficient and better oxidation stability. The purpose of this study is to investigate the performance of coconut oil based new hybrid CeO 2 /CuO nano-lubricant with various ratios of CeO 2 /CuO viz. 25/75, 50/50, and 75/25 at different concentrations (0.1, 0.25, 0.5, and 1.0 wt%). The rheological, thermal, thermo-gravimetric, and tribological evaluations were conducted for hybrid nano-lubricants and the results were compared with those of base oil (coconut oil) and nano-lubricants containing CeO 2 and CuO nano-particles individually. A reduction of 15.7% in average friction coefficient and 23.4% in wear scar diameter was observed with the use of 0.25 wt% CeO 2 /CuO: 50/50 hybrid. Oil degradation studies and worn surface analyses after engine test were also done. The results showed that the surface enhancement is evidenced with the use of hybrid nano-lubricant.