Experimental and model studies about the lubrication of physisorbed isobutane molecules on hydrogenated diamond-like carbon films.

Abstract As one amorphous carbon consisting of sp2 and sp3 bonding, diamond-like carbon (DLC) films present excellent tribological characteristics. Meanwhile, frictional properties could present great complexity with the varied interaction. In this work, research on the tribological performances of hydrogenated DLC films under the various isobutane conditions, which was similar to some polar fluids, was carried out. The results showed that friction coefficient increased with the isobutane amount. And the wear was constant after a certain amount of isobutane was adsorbed. Combining these experimental results with models, the mechanism has been proposed. It was the isobutane molecules physisorbed on the interface that prevented the hydrogenated DLC films from wear, resulting in the increasing of friction coefficient with gas pressure. Graphical abstract Unlabelled Image Highlights • The friction coefficient of hydrogenated DLC film increased with the amount of isobutane, yet the wear remained low. • The experimental results were supported by ab initio calculations and mathematical models. • Model studies showed that the physisorbed isobutane molecules dominated the tribological behavior of hydrogenated DLC film. [ABSTRACT FROM AUTHOR]