Frictional Behavior of Alumina-Coated Vertically Aligned Carbon Nanotube Forests: Implications for Micro and Nano Electromechanical Devices

Abstract

In this work, we report the role of alumina coating on frictional behavior of vertically aligned carbon nanotube (VACNT) forests sliding against an alumina microsphere as a counter surface using atomic force microscopy. A high coefficient of friction (COF) of ∼2.13 is observed for VACNT forest, while the COF reduced significantly to ∼0.45 for 20 nm alumina-coated VACNT forests. The fivefold reduction in the COF can be explained by considering the changes in the contact area and lateral stiffness. The effect of sliding speed on the COF is also investigated on both bare and alumina-coated VACNT forest samples. The COF does not show any dependency on sliding speed and confirms the consistent difference in friction force between bare and alumina-coated VACNTs over the investigated range of sliding speeds.