Evaluation of tribological performance of oxide nanoparticles in fully formulated engine oil and possible interacting mechanism at sliding contacts

Abstract The oxide nanoparticles have been claimed as the lubricant additive, which are capable of alleviating wear and reducing friction for the engine components. However, how oxide nanoparticles speficially behave together with the representative additive (Zinc dialkyl dithiophosphate, ZDDP) in the formulated engine oil, is still poorly understood. The results well revealed that the addition of oxide nanoparticles provided the improved lubricity of engine oil and significant resistance to wear. The Al2O3 nanoparticle specifically rendered superior tribological capability compared with other nanoparticles. Furthermore, the differentials of wearing mechanism, tribofilm and interface hierarchy were clarified by means of the morphological observation and compositional characterization. This study allowed us to understand the interacting mechanism when nanoparticles being involved within commercial engine oil was presenting between the sliding contact.