Composite Lubricating Films with Silane Coupling Agent-Modified Carbon Nanotubes on a Silicon Substrate with Enhanced Wear-Resistant Properties

A modified carbon nanotube composite film was designed and prepared by self-assembled molecular film technology. The carbon nanotubes modified by 3-glycidoxypropyltrimethoxy-silane (KH560) were grafted onto a silicon substrate by using N-3-(trimethoxysilyl)propylethyl-enediamine (DA) molecules as an intermediate connecting layer. Compared with the silicon surface, the surface wettability of the modified carbon nanotube composite thin film changes from super-hydrophilic to hydrophobic. At the nanoscale, the surface adhesion and friction forces decreased by nearly 91% and 87%, respectively, and at the microscale, the friction coefficient was reduced by 84%. The anti-wear lifetime is prolonged to 72 min under an applied load of 1 N, which is over 35 times longer than that of silicon. Due to the great wear-resistant properties of modified carbon nanotubes, they are expected to be widely used in micro/nanoelectromechanical systems.