The mechanisms of boundary lubrication and antioxidation of bromobenzo-15-crown-5 as novel additive

A synthesized compound, bromobenzo-15-crown-5, was evaluated as a novel additive in liquid paraffin. Results indicate bromobenzo-15-crown-5 exhibits excellent antiwear, antifriction properties as a novel additive, and better than that of zinc dialkyldithiophosphate (ZDDP) which is used worldwide as an effective additive. Adsorption on the sliding surface and the chemical changes occurring within a few nanometers of the surface are keys to the performance of lubricants and lubricant additives in the boundary lubrication regime. By means of the methods of modern surface science, the surface chemistry and boundary lubrication mechanism of bromobenzo-15-crown-5 as novel additive were elucidated. On the sliding surface, bromobenzo-15-crown-5 coordinated with ferrous ions and formed a strong reaction layer, which protected the underlying metal surface. In the base stock solution, bromobenzo-15-crown-5 coordinated with ferrous ions also and plays the role of capture reagent for ferrous ions, which catalyzes the oxidation of the base stock.