Nanotribology: basic friction processes

Tribology is the science that studies the phenomena that occur when two surfaces in contact undergo relative motion. It covers the phenomena of friction, adhesion, wear and lubrication. Tribology is a fundamentally interdisciplinary science, drawing on concepts from chemistry, materials science, fluid mechanics, solid state physics, rheology, crystallography, surface physical chemistry, thermodynamics and mathematics.

The study of friction forces is generally complicated. These forces depend on numerous variables that cannot always be controlled simultaneously. Often, it involves studying an interface that is difficult to observe during sliding. Moreover, a number of processes take place at different length and time scales, ranging from the macroscopic to the atomic, from the femtosecond to the century. For these reasons, fundamental understanding of the origin of frictional forces, or the complete characterization of tribological behavior, is always limited by technical means. Over the last thirty years, the development of new experimental techniques and the advent of increasingly sophisticated numerical simulations have enabled us to make significant progress, providing a better understanding of these phenomena.