The Tribological Study of Novel Benzotriazolyl-Containing Anticorrosive Polysulfides in Rapeseed Oil

Abstract

Two novel benzotriazolyl-containing polysulfides were synthesized as a part of the efforts of molecular design. The tribological properties of the synthetic products as additives in rapeseed oil were evaluated using a four-ball machine and compared with that of diiso-butylpolysulfides (DIBPS). The copper corrosion-inhibiting performance and thermal stabilities of the additives were explored as well. The results showed that the synthetic heterocyclic polysulfides had better corrosion-inhibiting properties and thermal stability than the DIBPS. Moreover, the heterocyclic polysulfide additives can improve extreme pressure properties of rapeseed oil as well as antiwear and friction-reducing abilities. However, compared with DIBPS, the heterocyclic polysulfide additives showed a little weaker performance. Tribofilms were investigated by means of scanning electron microscopy and X-ray photoelectron spectroscopy. Surface analysis indicated that the benzotriazolyl-containing polysulfides experienced tribochemical reactions with the rubbing steel surface to generate FeS and FeS2, which together with the chemically absorbed organic N-containing species formed a surface protective film and hence significantly reduce wear of the steel-steel frictional pair. The titled synthetic compounds could be used as promising environmentally friendly multifunctional lubricating additives.