Tribological Properties of Tungsten Disulfide Nanoparticles Surface-Capped by Oleylamine and Maleic Anhydride Dodecyl Ester as Additive in Diisooctylsebacate

Oleylamine (OM) and maleic anhydride dodecyl ester (MADE, synthesized at our laboratory) were adopted as the surface modifiers to prepare OM/MADE-capped tungsten disulfide (WS2) nanoparticles. An X-ray diffractometer and a transmission electron microscope were performed to analyze the microstructure and phase ingredients of the OM/MADE-capped WS2 nanoparticles. Moreover, a four-ball friction and wear tester and a reciprocating tribometer were employed to evaluate the tribological properties of the surface-capped WS2 nanoparticles as the lubricant additive in diisooctylsebacate (DIOS) from room temperature to 150 °C. The morphology of the worn steel surfaces and wear scars and their chemical states were investigated with a scanning electron microscope, three-dimensional profilometry, and an X-ray photoelectron spectroscope. Results show that OM-capped WS2 nanoparticles nearly have no effect on the tribological properties of the DIOS base oil. The OM/MADE-capped WS2 nanoparticles added in the same base stoc...