The tribological behaviors of succinimide-modified lanthanum hydroxide nanoparticles blended with zinc dialkyldithiophosphate as additives in liquid paraffin

Lanthanum hydroxide nanoparticles modified with succinimide (coded as Succ- nano La) were prepared in laboratory. The tribological behavior of the synt hesized nanoparticles blended with zinc dialkyldithiophosphate (ZDDP) as ad ditives in liquid paraffin (LP) to a total concentration of 5 wt.% was inve stigated on a four-ball machine. The surface morphologies and elemental dis tributions of the worn steel ball surfaces were examined with scanning elec tron microscopy (SEM) and electron probe microanalysis (EPMA), respectively . The chemical states of some typical elements on the worn steel surfaces w ere analyzed with X-ray photoelectron spectroscopy (XPS). As a result, the best extreme pressure behavior was obtained at a weight fraction of 1:4 for Succ-nano La/ZDDP. The best antiwear ability was obtained at a weight frac tion of 2:3 or 3:2 for Succ-nano La/ZDDP, which was accompanied by a parall el improvement in friction-reduction. Surface films consisting of La2O3, Zn O2, sulfides, N-containing organic compounds and P-containing compounds wer e detected. The improvement in the friction-reduction and antiwear properti es was attributed to these tribochemical products. (C) 2001 Elsevier Scienc e B.V. All rights reserved.