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DS: Dünne Schichten
DS 22: Postersitzung
DS 22.61: Poster
Tuesday, March 9, 2004, 14:30–17:00, Poster B
A new indentation concept for porous materials — •René Puschmann, Norbert Schwarzer, and Frank Richter — TU Chemnitz, Professur Physik fester Körper, 09107 Chemnitz, Deutschland
The talk describes indentation experiments on a porous SiOx layer. A new concept is introduced to overcome the problem of insufficient measurement methods and its underlain theories.
The examined material is a 1000 nm thick mesoporous xerogel on a standard Si (100) substrate. We utilised an UMIS 2000 tool. To avoid too high indentation depths and for reasons of symmetry only spherical indenter tips (radius 1 µm to 100 µm) were considered. The measurement procedure was a partial load-unload cycle that directly followed a normal loading-unloading cycle. A hysteresis in the load-depth-graph could be observed which is superimposed by a continuous depth shift.
The measuring data were evaluated by a new model based upon an analytical solution for the calculation of the elastic field in layered systems [1]. This approach might be considered as an extension of “Pharr’s concept of the effectively shaped indenter” [2]. It allows the separation of the elastic deformation even if plastic/elastic deformation has occurred during the indentation process.
[1] N. Schwarzer: “Arbitrary load distribution on a layered half space”, ASME J. Tribology 122 (2000) 4, pp. 672-681
[2] P. Heuer, N. Schwarzer, G. M. Pharr: “The concept of the effectively shaped indenter and its uses”, computer video animation, available for download at www.esae.de