Tribological Properties and Lubrication Mechanism of New Phosphorus-Free Benzothiazole Organomolybdenum Friction Modifiers

Benzothiazole is widely used in biomedical applications in recent studies, in this study we coordinated it with organic molybdenum to prepare three phosphorus-free benzothiazole-organic molybdenum friction modifiers with different structures and evaluated the lubrication performance in base oil PAO6. The results showed that the three additives exhibited different friction reduction and anti-wear effects due to their different molecular structures, with benzothiazole-molybdenum oleate amide (YSMo) showing the most significant lubrication performance. At 1.00 wt%, YSMo reduced the average coefficient of friction by 30.8% and the wear volume by 95.86%. The combination of sulfur-containing nitrogen heterocyclic compounds with molybdenum source significantly enhanced the lubrication performance and effectively reduced friction and wear through physical adsorption and the formation of a dense composite chemical friction protective film (containing components such as FeS, MoO₃, and MoS₂), which further confirmed that friction-generated MoS₂ has a positive effect on the tribological performance. The lubrication performance of YSMo was superior to that of the other two additives, which depended on the polar groups and chain lengths, which provides an important theoretical basis for further optimizing the design of lubricating additives.