Berlin 2005 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 24: Granular Matter

DY 24.7: Vortrag

Samstag, 5. März 2005, 15:45–16:00, TU H2032

Temperature-dependent resistivity of and compacted and sintered metal powders — •Martin Gabl, Norbert Memmel, and Erminald Bertel — Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria

Compaction and sintering of powders are two essential steps in the powder- metallurgical production process. Various empirical approaches have been developed in order to control these processes and to characterize the properties (such as porosity or mechanical strength) of the sample by easy to apply methods, such as resistivity measurements. Since the sample resistivity depends not only on the porosity, but also on the sample purity and the nature of the contacts between individual grains a single measurement of resistivity cannot provide sufficient information to charcterize the compacted and sintered metal powder. In the present work we demonstrate that the measurement of resistivity Rho as a function of temperature T allows separating the influence of sample purity and grain-to-grain contacts on the one hand from porosity on the other hand. The latter is uniquely related to the temperature dependence dRho/dT. We further show that dRho/dT as a function of porosity is correctly described by percolation theory.