In-situ formation of onion-like carbon film by tribo-induced catalytic degradation of hydrocarbon: Effect of lubrication condition and load
Xing Xu, Li Qiang, Fenghua Su, Jianfang Sun, Wenfang Li
Abstract
The method of extracting a carbon-based film from a lubricating medium has attracted considerable interest due to its sustainable lubrication capabilities. However, the effect of the lubrication conditions and applied loads on the in-situ formation mechanism of the carbon-based film remains unknown. Here, the tribological properties of the MoN-Ag coating lubricated with octadecane, oleic acid, and 1-octadecene were investigated using a ball-on-disk tribo-tester. The MoN-Ag coating's tribo-induced catalytic effects in these lubricating mediums were revealed by SEM-EDS, Raman, XPS, and TEM analysis. The results showed that the MoN-Ag coating could frictionally induce the degradation of these lubricating mediums to generate carbon-based film with an amorphous/onion-like structure. And the coating had a better tribo-induced catalytic effect in octadecane than the other lubricating mediums. In combination with the first-principles simulation, it was indicated that the in-situ formation ability of the carbon film depended on the lubricating medium's functional groups and adsorption energy. These findings refined the design theory of the tribo-induced catalytic system and introduced a novel concept for the selection of lubricating medium in engineering applications.