Study of the tribological behavior of S-(carboxylpropyl)-N-dialkyl dithiocarbamic acid as additives in water-based fluid

There has been a growing concern for the use of water-based fluids because of the worldwide interest in environmental issues. This has promoted the research and use of water-soluble additives as environmental friendly lubricants. A kind of potential water-soluble additive, S-(carboxylpropyl)-N-dialkyl dithiocarbamic acid was prepared in this work. The friction and wear behaviors of the synthesized compounds as an additive in water-based liquid were evaluated with a four-ball tester and a ring-on-block rig. The wear scar morphology of the ball and the chemical nature of the antiwear films generated on the steel counter face were investigated with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was found that the synthesized additives had excellent antiwear, load-carrying and extreme pressure performance. The additive reacted with the counter-face metal and generated a surface protective film consisting of FeS, FeS2, FeSO4 and an absorbed compound containing N and acid.