Frequency response of quartz crystal shear-resonator during an adhesive, elastic contact in a surface forces apparatus

Contact mechanics experiments on a single asperity contact between two dry mica surfaces have been performed with a surface forces apparatus where one mica surface was excited to oscillatory shear movements by a quartz-crystal resonator. We directly obtain the resonance parameters of the quartz and the radius of the adhesive contact (measured by optical interferometry) as a function of the external load. The frequency shift was found to increase linearly with increasing contact radius as predicted by the elastic point contact model by Laschitsch and Johannsmann [J. Appl. Phys. 85, 3759 (1999)]. The bandwidth increased more strongly than linearly with the contact radius, but not quadratically as predicted by the model. We attribute the differences to dissipative processes in the glue layers supporting the contacting surfaces. (C) 2002 American Institute of Physics