Microtribology and friction-induced material transfer in WS2 nanoparticle additives

The tribological behavior of platelet and nested colloidal particles of tun gsten disulfide was Studied using the surface forces apparatus, atomic forc e microscopy, lateral force microscopy, and Auger spectroscopy. Shear-induc ed material transfer from the colloidal particles to the surfaces was shown to be a dominant factor in the tribological behavior observed for both str uctures. An ultrathin, ordered layer was observed when nested particles wer e sheared, while WS2 platelets produced a rough and disordered transfer lay er, with substantially inferior lubricating properties.