Study on the tribological properties of the oils adding oleic acid-modified Fe₃O₄ nanoparticles

Fe₃O₄ nanoparticles of average diameter 10 nm, whose surface was modified with oleic acid, were prepared by chemical co-deposition method, and the tribological properties of the prepared nanoparticles as additive in 32 machine lubricating oils on M-200 tribotest were investigated. Results indicate the oils adding oleic acid-modified Fe₃O₄ nanoparticles exhibit good tribological properties. Friction coefficient decreases 26% maximally, and wear-scar width reduces 28% correspondingly. During the friction with the oils adding Fe₃O₄ nanoparticles, the variation of friction moment with time exhibits the time effect. The curve of surface topography shows that the worn surface obtained after tests with the oils adding Fe₃O₄ nanoparticles is smoother than that with the pure oils. Nano-Fe₃O₄ particles polishing the surface of friction pairs is contributed to the good tribological properties of the oils adding Fe₃O₄ nanoparticles.