The Understanding of the Microstructural Changes of Refractory Castables after Thermal Shocks through Damping Measurements

Nicolas Traon, Thorsten Tonnesen, Rainer Telle

GHI/RWTH-Aachen Institute of Mineral Engineering – Department of Ceramics and Refractory Materials 52062 Aachen/Germany

Revision 06.10.2011, 24.10.2011

Volume 4, Issue 2, Pages 121 - 126


The work herein correlates the damping measurements and the microstructural modifications of refractory castables after thermal shocks at air. According to DIN EN 993-11, thermal shocks at air at different temperatures (750, 850, 950 and 1050 °C) were progressively conducted on refractory samples based on tabular alumina with addition of partially stabilized zirconia (PSZ). The same thermal shocks were carried out at 950 °C on white fused alumina samples as well. The thermal shock damage evaluation of high-alumina refractory castables was based on dynamic Young’s modulus and damping characterization data obtained via the impulse excitation technique (IET), according to the ASTM E1876-07. Scanning electron microscopy (SEM) completes this survey so as to understand the elastic changes of these refractory formulations. The results show that the damping increase in PSZ castables may be explained by crack nucleation and propagation while such phenomena do not occur in WFA castable.


thermal shock, impulse, excitation technique, partially stabilized, zirconia, Young’s modulus, damping


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