Nanoscale Topography and Wear of Ceramic Interfaces and their effect on Macroscale Friction

500 years ago, Leonardo da Vinci systematically investigated the relation between the frictional force and normal force. Da Vinci concluded that the frictional force is proportional to the normal force. This simple relation between frictional force and normal force successfully captures most dry sliding friction behavior between macroscopic objects. However, when the sliding surfaces strongly adhere to each other or are atomically smooth, the proportionality between frictional force and normal force may breakdown and, in this case, the frictional force is proportional to the area of real contact. Analytical models have been proposed to quantify the area of real contact at multi-asperity interfaces. Experimentally it remains challenging to access and measure the area of real contact hidden from view by the contacting objects. To quantify the area of real contact, numerical methods, such as the boundary element method, have been developed. The calculation of contact mechanics either by analytical or numerical methods provides further insight into the formation of contacts which leads to friction. In this thesis, we investigate the interplay between friction, surface topography, capillary adhesion and third body formation at macroscopic sliding interfaces between ceramic materials.

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