Adhesion and size dependent friction anisotropy in boron nitride nanotubes

The frictional properties of individual multiwalled boron nitride nanotubes (BN-NTs) synthesized by chemical vapour deposition (CVD) and deposited on a silicon substrate are investigated using an atomic force microscope tip sliding along (longitudinal sliding) and across (transverse sliding) the tube’s principal axis. Because of the tube’s transverse deformations during the tip sliding, a larger friction coefficient is found for the transverse sliding as compared to the longitudinal sliding. Here, we show that the friction anisotropy in BN-NTs, defined as the ratio between transverse and longitudinal friction forces per unit area, increases with the nanotube–substrate contact area, estimated to be proportional to ( L NT R NT ) 1/2 , where L NT and R NT are the length and the radius of the nanotube, respectively. Larger contact area denotes stronger surface adhesion, resulting in a longitudinal friction coef…

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2012-10-22 14:01:24

Source: http://nanochemistry.blogspot.com/2012/10/adhesion-and-size-dependent-friction.html