Friction of fullerene-like WS2 nanoparticles:: effect of agglomeration

Inorganic fullerene-like (IF) solid lubricant nanoparticles with extremely useful tribological characteristics have been realized, offering a plethora of new applications for these nanomaterials. The IF nanoparticles were found to be in the aggregated state. The main goal of this work is to elucidate the effect of the mixing time of IF-WS2 nanomaterial in the oil on the size of the IF aggregates and their influence on the friction and wear. The fraction of small aggregate increases and that of the large aggregates decreases with longer mixing time. Consequently, the spread of the tribological results diminishes with the lengthening of the mixing time. The reproducibility of the friction results for the pairs lubricated with oil +IF nanoparticles is determined by distribution of the IF aggregates in the lubricant and the size of the solid lubricant aggregates.