Preparation, characterization and tribological properties of coal indirect liquefied diesel soot modified by oleylamine

Abstract Coal indirect liquefied diesel soot (Fischer-Tropsch synthesis diesel soot, F-T DS) was collected by burning coal indirect liquefied diesel (F-T Diesel) with a self-made soot trap device in the laboratory. F-T DS was modified with oleylamine modification method to obtain oleylamine modified F-T DS (F-T DS-OLA). The effect of 10# white oil with F-T DS or F-T DS-OLA on the lubrication performance was investigated using a long-time four-ball friction and wear tester. The composition, structure, morphology and tribological mechanism for F-T DS and F-T DS-OLA had been studied by using FTIR, XPS, Raman, XRD and other instruments. The results show that F-T DS modified by oleylamine can increase lipophilic groups. The average particle size of F-T DS and F-T DS-OLA are 64 nm and 38 nm respectively. The main structure component is amorphous carbon with a small amount of graphite crystallites. The average friction coefficient (AFC) first decreases and then increases as the mass fraction of F-T DS and F-T DS-OLA increases in 10# white oil. When the mass fraction of F-T DS is 0.6 wt%, the AFC reaches the minimum, and the AFC reaches the minimum when the mass fraction of F-T DS-OLA is 0.8 wt%. The average wears scar diameter (AWSD) of the steel ball also decreases first and then increases. F-T DS reaches the minimum at 0.6 wt%, and F-T DS-OLA reaches the minimum at 0.8 wt%. Comprehensive AFC and AWSD analysis, the antifriction and anti-wear effect of F-T DS is greatly improved after oleylamine modified. Through the analysis of the surface morphology of the upper ball wear scar and valence state of the surface elements, it can be obtained that the wear scar of the upper test ball becomes shallow after adding F-T DS-OLA. A lubricating film containing C, O and iron oxides is formed on the surface, which can improve the antifriction and anti-wear effects of 10# white oil.