Prepation and tribological investigation of a novel S-N style 1,3,4-thiadiazole-2-thione derivatives

Two non-phosphorus and ashless 1,3,4-thiadiazole-2-thione derivatives, 5-dodecyldithio-3-phenyl-1,3-4-thiadiazole-2-thione (DPTT) and 5-cetyldithio-3-phenyl-1,3,4-thiadiazole-2-thione (DHTT) were synthesized and confirmed by elemental analyses. Thermal degradation test were conducted to identify their thermal stabilities using a thermo-gravimetric analyzer (TGA). The tribological behavior of the synthesized compounds as additive in rapeseed oil (RSO) was examined by using four-ball friction and wear tester. The worn surface morphology and element chemical composition of rubbing film was analyzed by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the additives possess good thermal stabilities, these novel compounds as additives in the rapeseed oil were able to obviously decrease the wear rate and friction coefficient. The results of XPS analyses illustrate that the prepared compounds reacted with metal surface to form a film containing sulfate, sulfide, iron oxide and N-containing organic compounds, all these compounds contributed to the improved tribological properties of the rapeseed oil.