Neue Möglichkeiten der mechanischen Oberflächencharakterisierung mit Indentermethoden

Novel possibilities for the determination of mechanical properties of thin films are presented which are based on indentation experiments with spherical indenters. They arise from the combination of high accuracy measurements with a novel theoretical method which delivers three-dimensional analytical solutions for the stress and strain fields in layered materials. This approach allows the determination of the Young's modulus of thin films independent of the substrate properties even for films thinner than 100 nm which could not be characterized so far by indentation methods. In addition the yield strength can be determined due to an accurate determination of the transition between wholly elastic and elastoplastic deformation. The obtained data can be used to evaluate the protective action of films in dependence on the radius of the counterpart. The theoretical solutions for the elastic deformation of layered systems open up completely new possibilities for the modelling of layered systems as well as the evaluation of scratch and wear test results. It is assumed that the method can be used in the future for the determination of additional material parameters that are up to now not accessible to indentation tests.