Characterization and lubrication performance of diesel soot nanoparticles as oil lubricant additives

Abstract

Diesel soot, a complex product of incomplete combustion, enters lubricant oils and acts as an additive. Thus, diesel soot significantly affects the performance of lubricants. In particular, the dispersion and concentration of diesel soot in lubricant media performs a key function. In this study, diesel soot was dispersed in PAO 4 oil with 1 wt% sorbitan monooleate (Span 80) as a dispersing agent. The chemical and structural features of three kinds of diesel soot (from loader soot, cement tanker soot, and bulldozer soot) were monitored by AFM, TEM, XRD, FT-IR, and Raman spectroscopy. The tribological behavior of different concentrations of loader soot provided with the optimal physicochemical properties and dispersion properties in comparison with other soot types was investigated using a UTM-2 tribometer. Tribology test results showed that diesel soot, as an additive to PAO 4 oil, significantly reduced both friction and wear of steel balls and plates. The lubricant with a diesel soot concentration of 0.01 wt% exhibited the optimal anti-wear performance, with a wear rate reduction of 75.2%. Bearing effects, as well as chemical and electrochemical actions were the main anti-wear mechanisms of diesel soot as an oil additive.