High frequency tribological investigations on quartz resonator surfaces

We report on the application of quartz crystal resonators for friction measurements in the MHz regime. The dissipative processes are studied by approaching a small sphere to the quartz surface and measuring the shifts in frequency and bandwidth as a function of the sphere-sample distance. Once elastic contact is established, the frequency and the bandwidth can be well described by an increased stiffness of the quartz-sphere system. In the range of distances where contact is just being formed, we observe strongly different behavior for high-friction metal-metal interfaces and low-friction fluoropolymer interfaces. For high-friction interfaces there is an excess dissipation of energy which we attribute to frictional processes in the contact zone. (C) 1999 American Institute of Physics. [S0021-8979(99)02407-X].