Measuring nanomechanical properties of a dynamic contact using an indenter probe and quartz crystal microbalance

A study of the contact mechanics of a probe tip interacting with a quartz crystal microbalance (QCM) has been performed, involving simultaneous measurements of normal load, displacement, and contact stiffness with changes in QCM resonant frequency. For metal-metal and glass-metal contacts in air, the QCM frequency shifts were observed to be positive, and directly proportional to the contact area as inferred from the contact stiffness. Interfacial characteristics of the probe-tip contact (elasticity, contact size, and an estimate of the number of contacting asperities) were deduced by extending a prior model of single asperity contact to the case of multiple contacts. The extended model clarifies a number of seemingly disparate experimental results that have been reported in the literature. (C) 2001 American Institute of Physics.