Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 26: Poster Session
MM 26.10: Poster
Dienstag, 23. März 2010, 14:45–16:30, Poster C
Thermomechanical properties of mullite up to 1673 K: single crystal vs. ceramics — •Thomas Friedrich Krenzel1, Jürgen Schreuer1, and Hartmut Schneider2 — 1Ruhr University Bochum, Institute of Geology, Mineralogy and Geophysics, Bochum, Germany — 2University of Cologne, Institute of Crystallography, Köln, Germany
The poster by Adel Benlagra originally scheduled for MM 26.10 has been moved to TT 27.21.
Ceramics with mullite composition are well known and appreciated for their favourable properties like high thermal stability, low thermal expansion and conductivity or high creep resistance. They are extensively used as high temperature application materials e.g. like kiln furnitures, catalytic convertors, coatings or engineering ceramics.
Schreuer et al. [1] recently studied the mechanical properties of single crystals up to 1673 K and found an anomaly in the temperature evolution of the strains parallel to principle axes and furthermore a strong deviation from linearity of observed shear stiffnesses compared to calculated ones, both above about 1273 K. They proposed a glass-like transition at this temperature. Another research group interpreted similar or stepwise anomalies of different properties at same temperatures as a phase transition [2; 3].
Since this anomaly is not yet fully clarified the goal of this work is to bring up new aspects by a comparison of thermal expansion and elastic properties of mullite ceramics, which were prepared in different ways, with new single crystal data of higher resolution up to 1673 K. The measurements of thermal expansion and elastic properties were done with the help of dilatometry and resonant ultrasound spectroscopy, respectively.