Unexplored solid lubricity of Titanium nanoparticles in oil to modify the metallic interfaces

Abstract

The nanoparticles (NPs) of Titanium (Ti) were explored for the first time to enhance the tribo-performance of group III base oil. Its Hexagonal Close Packed (HCP) crystal structure indicates the likelihood to show solid lubricity, although nothing is reported on this. Concentration of NPs in oil was varied from 0.1 to 2 wt% in the presence of a dispersant (1 wt%). The anti-wear-AW, anti-friction -AF, and extreme pressure- EP properties of formulated lubricants were evaluated on a four-ball tester with steel–steel contact in a boundary lubrication regime. The EP performance of base oil was unaffected by the addition of NPs. However, a significant reduction in wear (∼45%) and friction (64%) was exhibited by 0.5 wt% of NPs, the highest in the series. The tribo-films formed at the interface of the ball surface during the AW tests were characterized using scanning electron microscopy (SEM), coupled with energy-dispersive X-ray spectroscopy (EDS) and Raman and XPS Spectroscopy. The excellent AW by Ti nano-oils was due to the tribofilm composed of embedded Tiparticles in the form of FeTiO3. The novelty of the work lies in the maiden attempt to explore the lubricity of Ti NPs in oil and to optimize the concentration for best possible enhancement in AW and AF performance.