View in EDS

On the closure of thermally induced micro-cracks in aluminum titanate ceramics.

Saved in:
Bibliographic Details
Title: On the closure of thermally induced micro-cracks in aluminum titanate ceramics.
Authors: Buljak, Vladimir1,2 (AUTHOR) vladimir.buljak@polimi.it, Serrano-Munoz, Itziar2 (AUTHOR), Kupsch, Andreas2 (AUTHOR), Müller, Bernd R.2 (AUTHOR), Prasek, Marko3 (AUTHOR), Contillo, Adriano3 (AUTHOR), Mouiya, Mossaab4,5 (AUTHOR), Huger, Marc4 (AUTHOR), Bruno, Giovanni1,2 (AUTHOR) giovanni.bruno@bam.de
Source: Ceramics International. Nov2025:Part C, Vol. 51 Issue 27, p55141-55152. 12p.
Subject Terms: *ALUMINUM titanate, *MICROCRACKS, *X-ray diffraction measurement, *FINITE element method, *THERMAL expansion, *APPLIED sciences, *CERAMICS, *YOUNG'S modulus
Abstract: Aluminum Titanate (AT) refractory ceramics (as some other ceramic composites) are prone to microcracking, due to the thermal expansion anisotropy of AT and to the mismatch with the thermal expansion of the constituents. Such microcracks cause the room temperature Young's modulus to be only a fraction of that of the non-microcracked material. As a function of temperature, the Young's modulus increases non-linearly. Such increase suggests that microcracks close or even heal at high temperatures. Upon cooling, thermal stress accumulates again, and microcracks re-open. This cycle is fully reversible. While confirming the hysteretic behavior of the Young's modulus, we observe that the amount of microcracks (as determined by in-situ Synchrotron X-ray refraction radiography) decreases linearly upon heating. The apparent mismatch between the Young's modulus and the microcrack content dependence on temperature is explained by a simple FEM model. Such model employs cohesive elements upon cooling, in order to estimate the amount of initial microcracks. On purpose, the model does not include healing upon heating and only allows crack closure. It predicts that crack closure continuously occurs upon heating, thereby qualitatively reproducing the nearly linear dependence of the X-ray refraction signal. It is therefore concluded that the sudden and non-linear increase of Young's modulus with temperature is mainly caused by crack healing. Such finding agrees with previous work and paves the road to a more systematic separation of crack closure and healing in flexible ceramics. [ABSTRACT FROM AUTHOR]
Database: Academic Search Index
Description
Abstract:Aluminum Titanate (AT) refractory ceramics (as some other ceramic composites) are prone to microcracking, due to the thermal expansion anisotropy of AT and to the mismatch with the thermal expansion of the constituents. Such microcracks cause the room temperature Young's modulus to be only a fraction of that of the non-microcracked material. As a function of temperature, the Young's modulus increases non-linearly. Such increase suggests that microcracks close or even heal at high temperatures. Upon cooling, thermal stress accumulates again, and microcracks re-open. This cycle is fully reversible. While confirming the hysteretic behavior of the Young's modulus, we observe that the amount of microcracks (as determined by in-situ Synchrotron X-ray refraction radiography) decreases linearly upon heating. The apparent mismatch between the Young's modulus and the microcrack content dependence on temperature is explained by a simple FEM model. Such model employs cohesive elements upon cooling, in order to estimate the amount of initial microcracks. On purpose, the model does not include healing upon heating and only allows crack closure. It predicts that crack closure continuously occurs upon heating, thereby qualitatively reproducing the nearly linear dependence of the X-ray refraction signal. It is therefore concluded that the sudden and non-linear increase of Young's modulus with temperature is mainly caused by crack healing. Such finding agrees with previous work and paves the road to a more systematic separation of crack closure and healing in flexible ceramics. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2025.09.237