ATOMIC-SCALE FRICTION AND WEAR OF MICA

The frictional behavior of mica surfaces with silicon nitride tips has been investigated systematically with the AFM as a function of load, tip geometry, mica lattice orientation and humidity. Frictional forces are found to be proportional to loads between 10 and 80 nN. The frict ion coefficient is quite reproducible for different samples, tip radii , scanning speed and direction. At low loads, however, a non-linear be havior of the friction versus load is observed. At high (> 70%) relati ve humidity and in water, friction is reduced. Repeated scanning of mi ca surfaces shows layer-by-layer wear processes.