Loading rate effect on lateral force measurements on nanostructured Ti and TiN thin films

In the first set, the scratch length and duration were kept constant. In the second one, the scratch duration was tuned in order to achieve a constant value of the normal loading rate ⅆFzⅆt. In this last case, the experimental data leads to a unique curve. This means that during nanoscratch measurements, normal tip displacement is controlled by the normal force loading rate. Consequently, lateral displacement speed ⅆxⅆt must be tuned in order to obtain the required value of ⅆFzⅆt. This behaviour seems to be universal and not related to material hardness and Young modulus.