Preparation, Characterization, and Tribological Evaluation of Triethanolamine Monooleate-Modified Lanthanum Borate Nanoparticles

To develop a potential substitute for conventional lubricant additive, lanthanum borate nanoparticles modified by triethanolamine monooleate (TEMO-LaB) were prepared. The composition and microstructures of the samples were characterized by inductively coupled plasma optical emission spectroscopy, X-ray power diffraction, infrared spectra, transmission electron microscope, and thermogravimetric analysis. The results indicate that TEMO-LaB with the size around 50 nm is amorphous and the composition is La 2 [B 4 O 5 (OH) 4 ] 3 . Tribological properties of the prepared nanoparticles were evaluated using a four-ball tribometer and compared with a commercial borate ester (Vanlube 289). The results show that TEMO-LaB has better friction-reducing property in base oil than Vanlube 289. A three-dimensional non-contact surface profilometer was used to explore the morphology of the worn surface and X-ray photoelectron spectroscopy analysis was carried out. Based on the results of surface analysis, the action mechanism of nanoparticles during the friction process was preliminarily discussed.