The effect of particle size on the lubricating properties of colloidal polystyrene used as water based lubrication additive

A series of colloidal polystyrene (PSt) with different average diameters (110–368 nm) were prepared. Four-ball test results show that the load carrying capability of the relevant water based fluid is proportional to the average diameter of the PSt. However, there is no obvious effect of particle size on wear reduction with PSt. It is also found that sulfur in the emulsifier makes no contribution to the EP property of the fluid through comparative tests. Based on scan electron microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy examinations of the worn surfaces, it is supposed that the load carrying and anti-wear capabilities of the fluids with PSt are associated with the penetration of PSt particles into the rubbing surfaces during sliding.