2. Composite wear

Generally speaking, the use of composites containing one or more polymers and, possibly, other types of materials serves a fourfold purpose:

• enable them to withstand the normal force applied: mechanical reinforcement effect by increasing Young's modulus, compressive strength σ _Rc , hardness... ;

• extend the operating temperature and/or mechanical power range PΔu ;

• check the level of friction: note that it is not always desirable to reduce it, as in the case of brake pads, for example;

• reduce and/or stabilize wear speed at an acceptable level, which is always a desirable objective.

To a first approximation, the volume properties of a composite (at least if it has...