Tribological Behaviors of S,B-Containing Morpholine Derivatives as Additives in Rapeseed Oil

Two novel ashless and non-phosphorus S,B-containing morpholine derivatives,MBOC and MBOD,were prepared and their tribological behaviors in rapeseed oil (RSO) were evaluated using a four-ball tester.Thermal degradation tests were conducted to identify their thermal stabilities using a thermo-gravimetric analyzer.The worn surfaces of the steel balls were investigated by scanning electron microscopy (SEM).The results indicated that the additives possessed high thermal stabilities and good load-carrying capacities.Moreover,they both had good anti-wear and friction reducing property at a relatively high concentration (1.5 m%) and under all test loads.The resuits of XPS analyses illustrated that the prepared compounds as additives in RSO could form a protective film containing inorganic sulfide,sulfate,oxidized compounds and organic nitrogen-containing compounds on the metal surface during the sliding process.