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SYME: Mechanical Properties of Thin Films

SYME V: HV V

SYME V.1: Hauptvortrag

Dienstag, 12. März 2002, 17:00–17:30, H 16

Investigation of Mechanical Properties of Thin Films by Nanoindentation — •Thomas Chudoba — Institut für Physik, Technische Universität Chemnitz, Chemnitz, Germany

Despite the technical and methodical progress in nanoindentation technique it is still very difficult to obtain accurate values for mechanical properties of coatings below 2 µ m thickness. The reasons for this are explained by means of several examples. Some alternatives will be presented.

Experimental difficulties and their solutions will be explained for the detection of the true surface position, the creep behavior under load and the measurement of the indenter area function including pile-up and sink-in effects. To obtain pure film properties the measurement conditions have to be chosen in a way that a substrate influence can be minimized. This is shown by means of depth dependent hardness and modulus results of some film-substrate combinations. The natural tip rounding of sharp indenters generates a physical thickness limit, where comparable hardness measurements are impossible.

Alternatives are measurements with spherical indenters, which can be combined with elastic stress and deformation modeling. Modulus measurements down to 5nm film thickness became possible. Spherical indenters allow additionally the measurement of the yield strength instead of the hardness, which may serve as input parameter for the calculation of the load carrying capacity of coated systems.