Tribochemistry of 1-Octene on Three Transition Metal Surfaces: Fe(100), Pt(111) and Ni(111)

Recent studies have shown that transition metal nanoparticles in the friction pair surface coating or as lubricant additives can catalyze poly alpha-olefin (PAO) to form carbon-based films in-situ on the friction pair surface, playing a role in friction reduction. Knowing the chemical evolutions of olefins, the basic component of PAO, on the catalytic metal surface is critical to understanding the formation of the carbon film. Here, we used reactive molecular dynamics (ReaxFF-MD) to study the reaction mechanism of 1-octene, a representative molecule of PAO, on the surfaces of Fe(100), Pt(111) and Ni(111) under boundary lubrication. The result shows that all three metal surfaces can catalyze the dehydrogenation of octene after charge transfer when contacting octene at 900 K, the decomposition and polymerization of carbon chains were observed on the surface of platinum and nickel, but not on iron surfaces, which is due to the strong interaction between carbon and iron, and the displacement of carbon chains are limited by the iron surface. Similarly, the different interaction strength between carbon and different metals affects the distribution and movement of the carbon chain at the interface, thus affecting the shearing behavior and causing the difference in friction. These atomic insights into the chemical evolution and friction mechanisms are helpful for the use of different transition metals as catalysts in engineering applications. (GRAPHICS)