Session K9 - Tribology II: Energy Dissipation & Sliding Mechanisms.
MIXED session, Wednesday morning, March 22
102D, MCC
The investigation of the modifications of the nano-scale tribological properties of boron carbide films induced by the energy dissipation at the interface between the atomic force microscope tip and the film surface is presented. It is shown that the microscope tip induces a modification at the surface that results in a decrease on the friction forces between the tip and the film surface. The influences of the friction coefficient, the scanning speed and the applied normal force on the film wear are investigated. Using a microscopic model, the dissipated energy at the tip-surface interface during scanning was estimated. The influence of the dissipated energy on the nano-scale wear is presented and a strong correlation between friction and wear, in nano-scale, is shown. The influence of capillary condensation of water (on the atomic force microscopy tip and boron carbide films surface) on the friction forces and wear of the films was also studied. It is shown that friction and wear are strongly dependent on the humidity. At low humidity no wear at the films surface is observed while at high humidities a constant wear rate is measured. The presented results show that the wear mechanisms of boron carbide films is highly dependent on the environment humidity. A wear model based on a film-surface interaction with the moisture in the air, induced by the dissipated energy at the microscope tip-surface interface while in relative motion, is presented.