Minimizing of the boundary friction coefficient in automotive engines using Al₂O₃ and TiO₂ nanoparticles

Minimizing of the boundary friction coefficient is critical for engine efficiency improvement. It is known that the tribological behavior has a major role in controlling the performance of automotive engines in terms of the fuel consumption. The purpose of this research is an experimental study to minimize the boundary friction coefficient via nano-lubricant additives. The tribological characteristics of Al₂O₃ and TiO₂ nano-lubricants were evaluated under reciprocating test conditions to simulate a piston ring/cylinder liner interface in automotive engines. The nanoparticles were suspended in a commercially available lubricant in a concentration of 0.25 wt.% to formulate the nano-lubricants. The Al₂O₃ and TiO₂ nanoparticles had sizes of 8–12 and 10 nm, respectively. The experimental results have shown that the boundary friction coefficient reduced by 35–51% near the top and bottom dead center of the stroke (TDC and BDC) for the Al₂O₃ and TiO₂ nano-lubricants, respectively. The anti-wear mechanism was generated via the formation of protective films on the worn surfaces of the ring and liner. These results will be a promising approach for improving fuel economy in automotive.