Tribological performance of some polyoxyethylene dithiophosphate derivatives water solutions

Tribological properties of water solution of some polyethoxyglycol esters of dithiophosphate acid derivatives have been tested using four-ball and ball-on-disk machines. The wear scar diameters (WSD), initial seizure, weld loads (WLs) and friction coefficients were estimated. The load-carrying properties and friction reduction were dependent upon the chemical structure of the additive molecule, additive concentration, sliding speed and load. Worn surfaces of balls were analysed using SEM/EDX technique, the highest worn surface concentrations for the most additives are observed for sulphur and phosphorous. Tested additives show very good load-carrying performances and strongly reduced friction coefficients compared to water, alone.