3. Force-penetration curve analysis

Nanoindentation is used to determine the mechanical properties of surfaces or thin layers, in particular their hardness and reduced modulus of elasticity. This technique involves pressing a rigid tip of known geometry perpendicularly into the surface of the material being studied and continuously monitoring the depth of penetration as a function of the applied load (normal load F _z ). By performing this load-unload cycle, a characteristic force-penetration curve is obtained (figure 11 ). Ultimately, analysis of the discharge curve allows models to be used to determine the relevant parameter, which is the projected contact area between the indenter and the material...