Tribological behaviour of three S-containing triazine derivatives and their synergetic effect with zinc dialkyldithiophosphate as additives

Abstract

The antiwear properties of three S-containing triazine derivatives with different active groups, referred to as TOSS, HOT, and HOMA, as additives in mineral oil, were evaluated using a four-ball friction and wear tester. Their thermal stabilities were investigated and the results suggest that all the synthesized compounds have good thermal stability. It was found that all the three S-containing triazine compounds added to the mineral oil showed rather good tribological behaviour, and the synergism between HOMA and zinc dialkyldithiophosphate (ZDDP) is better than that between ZDDP and HOT/TOSS. The worn surfaces of the steel balls were observed using X-ray photoelectron spectroscope. It is supposed that the synthetic additives adsorb and react with the steel surface during the process and thus generate a surface protective film composed of sulphate, iron oxide, and N-, O-, and S-containing organic compounds, which accounts for the better tribological behaviours of the base stock containing the synthetic additives when compared with the base stock alone.