TiO₂ Nanoparticles Coated with Nitrogen-Doped Amorphous Carbon as Lubricant Additives in Engine Oil

Abstract

Nanoparticle-dispersed lubricants reduce friction and wear of tribo-pairs by providing nanoscale polishing and asperity filling mechanisms. But these particles also have an adverse effect on the lubrication due to the agglomeration and poor interaction with the tribo-interface. Herein, we explore the effect of surface modification of TiO2 nanoparticles on the tribological properties of commercial engine oil. Surface modifications of TiO2 nanoparticles are done by coating layers of amorphous carbon and nitrogen-doped amorphous carbon. Investigations of the tribological properties of surface-modified TiO2 nanoparticle-dispersed oils show improved performance due to high dispersibility in engine oil. There is a decrease in the coefficient of friction by ∼35% and the wear scar diameter by ∼27% when compared to the base oil. Both a surface roughness reduction of ∼85% and a wear depth profile reduction of ∼88% are due to the nanoscale polishing mechanism at the tribo-interface by nanoparticles. To gain insights of the effects of oil concentration and ball types on the wear scar diameter, a statistical approach is employed. The analysis of variance test yields that the different oil concentrations have a significant effect on the wear scar diameter. The trends obtained from this statistical test are consistent with the experimental results. This novel approach opens up exploring advanced methods of statistical analysis for tribological applications.

Exploring the Impact of Additives on Tribological Characteristics in Lubricating Oils: A Critical Review

“…Rubbing action was reduced by more than two-fold, and wear exhibited a noteworthy decrease ranging from 5 to 9 times. The study discovered that either the adhesion of thin MoS2 nano-sheets through one of the four proposed submechanisms or the compaction and deformation of nanotube aggregates, resulting in the formation of a more substantial boundary film, were accountable for the protective and lowshear film formation on the surface [37,38]. The analysis in this case disproved the possibility of nanotube rolling, highlighting the fact that the exfoliation and deformation of the nanotubes were the main consequences in the boundaryoiling domain [39].…”

“…Tests were carried out under boundary-lubrication conditions; apply a contact pressure of 1 GPa and 0.005 m/s of sliding velocity through a ball-on-disc tribometer. When MoS2 nanotubes were added to the initial lubricant, the findings indicated a significant reduction in wear and friction as contrasted with the reference base oil [36,38]. Rubbing action was reduced by more than two-fold, and wear exhibited a noteworthy decrease ranging from 5 to 9 times.…”

Magnesium Hydroxy Silicate Enhanced Polytetrafluoroethylene Nanoparticles as Lubricant Additives: Preparation, Tribological Performance, and Lubrication Mechanism

“…The additives in the base oil have significant friction reduction and excellent antiwear properties in the friction pair. Nanomaterials, an emerging category of materials, have demonstrated their utility in various domains of tribology by offering exceptional lubrication performance as additives to lubricating lubricants. − …”