Tribological behavior of organic formulated anti-wear additive under high frequency reciprocating rig and unidirectional orientations: Particles transport behavior and film formation mechanism

Tribological behavior of Eichhornia crassipes nanotubes (EC-CNT) particles and transport phenomenon, which affect the tribological characteristic of the lubricant was investigated in this study. The investigation employed unidirectional and reciprocating sliding tribo-meter. The study was done in terms of friction and wear diameter reduction and surface wear analysis. EC-CNT particle concentration of 0.5, 1, 1.5 wt% were used alongside base rapeseed oil. Friction reduction using 1 wt% EC-CNT nanoparticle under unidirectional testing mode was 49% while reciprocating mode was 58.1% against base lubricant. However, wear scar radius reduction under unidirectional mode was 23.4%, observed closer to base oil lubricated wear scar radius 207.03 µm, whereas reciprocating has 52.2% compared to base oil lubricated wear radius 183.7 µm. The orientation mode analysis revealed that particles were found accumulated at the ball front for both modes and appear more under unidirectional mode leading to starvation of lubricant at the sliding contact region. Also, crushing of particles was observed in both operations both much with reciprocating sliding condition. Furthermore, wide flat film growth structure was found with reciprocating mode, thereby makes lubricant accessible to the sliding contact zone, leading to outstanding friction and wear reduction. • Eichhornia crassipes carbon nanotubes (EC-CNTs) product was used in this study due to its eco-friendly nature. • Sliding orientation affects the lubrication behavior of EC-CNT particle additives. • The flow pattern of nano-EC-CNTs governs the tribological performance. • Starvation of lubricant caused by the EC-CNTs accumulation is much found in unidirectional mode, thus affect the performance. • Reciprocating mode causes fast film formation growth along the sliding contact, with recommended tribological performance.