Copper Nanoparticles—A Promising Additive for Lubrication of Hydrogen Technology

Abstract Bearings used in hydrogen technology face significant lubrication challenges. The main difficulty stems from hydrogen molecules dissociating into atoms on the nascent wear sites and diffusing into steel, ultimately causing hydrogen embrittlement and failure of tribological components. Lubricant additives that rapidly form tribofilms, such as antiwear and extreme pressure additives, can suppress atomic hydrogen generation and permeation in steel, but the resulting tribofilms tend to increase friction. Nanol™, a sustainable copper-based nanoadditive capable of forming stable dispersions in oils, offers unique friction-modifying, antiwear, and thermal advantages. In this study, Nanol™ dispersed in a polyalphaolefin base oil was used to lubricate ball and roller bearings undergoing rolling contact fatigue tests under boundary lubrication conditions in a hydrogen environment. Beyond its ability to reduce friction by immediately decreasing the real-contact area between the moving parts, Nanol™ also reacts with nascent iron to form cohesive, low-friction tribofilms composed of copper and iron oleate on the wear track. These mechanisms, along with the properties of the chemically formed tribofilm, were key to lowering friction and extending the fatigue life of the bearings operating in hydrogen and under severe conditions.