Title :
The origin of ultrasound-induced friction reduction in microscopic mechanical contacts
Author :
Hesjedal, Thorsten ; Behme, Gerd
Author_Institution :
Dept. of Electr. Eng., Stanford Univ., CA, USA
fDate :
3/1/2002 12:00:00 AM
Abstract :
We present a study of the origin of ultrasound-induced friction reduction in microscopic mechanical contacts. The effect of friction reduction caused by Rayleigh-type surface acoustic waves (SAWs) is demonstrated for propagating and two-dimensional, standing wave fields using lateral force microscopy (LFM). It is shown that with increasing wave amplitude, friction is completely suppressed. To detect and distinguish between the effect of lateral and vertical surface oscillation components on the cantilever movement, we employed multimode scanning acoustic force microscopy (SAFM). We found that the friction reduction effect is only due to the vertical oscillation component. Because this effect does not appear for purely in-plane polarized Love waves, we concluded that the mechanical diode effect is most probably responsible for the SAW-induced lubrication. This explanation is also supported by vertical and longitudinal SAFM measurements, which show that, in areas where friction is completely suppressed, low frequency vertical cantilever oscillations can still be observed, whereas lateral or torsional oscillations are no longer excited.
Keywords :
Love waves; Rayleigh waves; acoustic microscopy; friction; lubrication; mechanical contact; surface acoustic waves; ultrasonic effects; Love wave; Rayleigh wave; cantilever oscillation; lateral force microscopy; lubrication; mechanical contact; propagating wave field; scanning acoustic force microscopy; surface acoustic wave; two-dimensional standing wave field; ultrasound-induced friction reduction; Acoustic propagation; Acoustic signal detection; Acoustic waves; Diodes; Friction; Microscopy; Polarization; Sawing machines; Surface acoustic waves; Ultrasonic imaging; Acoustics; Equipment Design; Friction; Lubrication; Microelectrodes; Microscopy, Atomic Force; Miniaturization; Nanotechnology; Radio Waves; Sensitivity and Specificity; Silicon; Transducers; Ultrasonics;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on