Abstract: Ag₂S nanoparticles were prepared in two different W/O microemulsions, the structure and morphologies of as-prepared Ag₂S nanoparticles were characterized by means of X-ray powder diffraction (XRD), transmission electron microscope (TEM). The tribological properties of liquid paraffin containing Ag₂S nanoparticles were evaluated on a four-ball test machine, the worn steel surface morphology were analyzed by using of scanning electron microscope (SEM). Results show that Ag₂S nanoparticles synthesized in two microemulsions, i.e. isooctane/sodium oleate/n-pentanol/water solution (sampleⅠ) and liquid paraffin/Span 80-Tween 80/n-butanol/water solution (sampleⅡ) both possess monocline crystal structure, and exhibit an even grain distribution. They have average particle size of 18nm and 5nm, respectively. The antiwear tests show that Ag₂S nanoparticles dispersed in liquid paraffin processed from liquid paraffin/Span 80-Tween 80/n-butanol/ water solution microemulsion exhibit good antiwear properties which can improve load carrying capacity of the base oil remarkably.

Key words: Ag₂S, nanoparticles, microemulsion, antiwear properties