An experimental study on tribofilm formation and endurance with nanolubricants

ABSTRACT This work investigates the formation, endurance and rupture of tribofilms on a honed engine liner subjected to boundary lubrication in a reciprocating Tribometer. Study focuses on the exploration of synergistic effect between ZDDP additive in the oil and two distinctly shaped nanoparticles, Graphene oxide (GO) and detonation nanodiamond (DND), in improving the characteristics of tribofilm. Tested samples were examined by scanning electron microscope and energy dispersive X-ray. The results indicated that the addition of nanoparticles to the base oil with ZDDP accelerates the tribofilm-formation. Although fully developed tribofilms were obtained with both the nanoadditives, the DND based tribofilm was more durable under the dry running conditions. However, P-rich tribofilm formed in the presence of GO showed self-mending characteristics. Nanoindentation studies on the wear tack revealed a 12% increase in elastic modulus and 23% increase in average hardness for the sample tested with DND compared to that of base lubricant. GRAPHICAL ABSTRACT