Surface activity of high-temperature perfluoropolyalkylether oil additives

Three additive materials for perfluoropolyalkylether-based high-temperature engine oils were studied, a bis-substituted dibenzothiazole, a diphenyl ether and a triphenyl phosphine. The focus of this work was to understand how the additives interacted with various surfaces to provide either anticorrosion or antiwear activity. In the case of the bis-substituted dibenzothiazole, the additive was found to form a thick, protective anticorrosion layer on the surface. The diphenyl ether served as another equally effective anticorrosion additive but failed to demonstrate surface activity. The third additive compound, triphenyl phosphine, was found to break down at the surface and form an inorganic polyphosphate which provided a level of both anticorrosion and antiwear function.