Durable superlubricity of hydrogenated diamond-like carbon film against different friction pairs depending on their interfacial interaction

Superlubricity of hydrogenated diamond-like carbon (H-DLC) film in vacuum was achieved against four different friction pairs (ZrO2, Al2O3, Si3N4 and SiC) due to the formation of graphene and nanoscrolls in transfer layer as well as the graphitization of contacted substrate; however, the durability of superlubricity was significantly diverse. The Al2O3/H-DLC pair presents much longer superlubricity lifetime than other three tribology systems. Combining with the experimental characterizations and the first principles calculation results, the synergistic effects from mechanical action and interfacial adhesion interaction between two sliding surfaces were found to mainly respond to the superlubricity failure of H-DLC films. High mechanical action or/and strong interfacial adhesion interaction facilitated the wear of counterface or H-DLC substrate, either of which would largely weaken the durability of superlubricity. Through with the similar mechanical action compared to the Si3N4/HDLC interface, the Al2O3/H-DLC interface was capable of durable superlubricity since the much weaker interfacial adhesion interaction helps maintain the stable transfer layer on the ball surface and form smoothly graphitized substrate surface in the contacted region.