Towards superlubricity in nanostructured surfaces: the role of van der Waals forces

摘要: Hydrogenated amorphous carbon (a-C:H) thin films have a unique combination of properties that are fundamental in mechanical and electromechanical devices aimed at energy efficiency issues. The literature brings wealth information about the ultra-low friction (superlubricity) mechanism a-C:H films. However, there is persistent controversy concerning physicochemical mechanisms contact mechanics atomic/molecular level role electrical interactions sliding interface still matter debate. We find hydrogenation outermost nanostructured surface atomic layers proportional to potential also forces arising interface. A higher hydrogen-to-carbon ratio reduces potential, directly affecting frictional by less effective long-term interaction. structural attributed lower polarizability layer due hydrogen density, which renders weaker van der Waals forces, particular London dispersion forces. More hydrogenated nanodomains proposed be used tailor superlubricity.