On the non-linear mechanical behavior of carbon-bonded alumina at high temperatures

Reference Presenter Authors
(Institution)
Abstract
14-015 Bruno Luchini Luchini, B.(Institute of Ceramics, Glass and Construction Materials. TU-Freiberg); Grabenhorst, J.(Institute of Ceramics, Glass and Construction Materials. TU-Freiberg); Fruhstorfer, J.(Institute of Ceramics, Glass and Construction Materials. TU-Freiberg); Pandolfelli, V.C.(Universidade Federal de São Carlos); Aneziris, C.G.(Institute of Ceramics, Glass and Construction Materials. TU-Freiberg);

In this study it was investigated the origin of the non-linear Young’s modulus behavior of carbon-bonded materials at high temperatures, specifically carbon-bonded alumina, a key-role material for the steel industry. The research was comprised of experimental measurements and numerical predictions, which in combination offered a complete and original explanation about the complex behavior of this material at high temperatures. Microscopic investigations revealed network-shape cracks dispersed in the carbonaceous matrix, as well as gaps between the matrix and the alumina particles. The former are related to the release of volatiles during firing and also due to the high thermal expansion anisotropy of graphite. The latter are function of the thermal expansion mismatch between alumina and the carbonaceous matrix. During re-heating, the closure of cracks and gaps among particles and matrix ruled the expansion behavior and a non-linear increase of the effective Young’s modulus as function of temperature was observed.  Finite element simulations using the concept of model materials were in excellent agreement with the experimental results, demonstrating the approaches’ potential.