Effect of Low Concentrations of Organophosphorus Additives on Tribological Performance of Polyalkylene Glycol-Based Oils for Tin Bronze on Tungsten Carbide Applications

Low concentrations of organophosphorus additives in PAG oil for friction units are under consideration. Concentrations of 0.1–0.5 percent maintain the environmental friendliness of the oil, but can improve its tribological properties. The friction pair (tin bronze versus tungsten carbide) was made from a plunger and compressor seal. It was tested in the reciprocating sliding mode under a load of 600 N (contact pressure ≈ 13 P), a frequency of 8.33 Hz, an amplitude of 15 mm and a temperature of +70 °C. It was found that the phosphate concentration of 0.2 percent provides the most stable values of the friction coefficient (0.04). The mechanism of action of the modifier was determined by analyzing the results of SEM and profilometry. Organophosphates make both interacting surfaces smoother; and there is an optimal concentration of additives that provides optimal roughness.