1. Definitions

1.1 Problem position

It's important to distinguish between two ways of approaching wear problems:

• we can consider the wear of a tribological system made up of two bodies, the environment and the interfacial product or third body. In this case, the phenomena must be described on the basis of the behavior of the interfacial material, whose presence and properties are paramount, as its behavior defines the way in which the first bodies are stressed. We then speak of the life of the third body, wear debris, particle flow, tribological circuit (recirculation or not of particles lost through contact), etc. ... ;

• a second approach, complementary to the previous one, consists in considering the wear of a rubbing...