Glass - Back to the Future!

Presenting Author:
Cécile Jousseaume

article posted 18 May 2016

Dr. Cécile Jousseaume is Research Associate at Saint-Gobain Research center (Expertise Composite Crystalline Materials Department) in Aubervilliers (France).

Crystallization in the Li2O-Al2O3-SiO2 glass system

C Jousseaume 1*, P Vilato 2, E Lecomte 2, C Patzig 3, T Höche 3
1 Saint-Gobain Recherche, 39 quai Lucien Lefranc 93303 Aubervilliers Cedex, France
2 Eurokera, 1 bis avenue du Général de Gaulle, 02400 Chierry, France
3 Fraunhofer-Institut für Mikrostruktur von Werkstoffen und Systemen Walter-Hülse-Straße 1, 06120 Halle, Germany

Low expansion glass-ceramics in the Li2O-SiO2-Al2O3 system are highly technical products manufactured for various applications, such as cooktops panels, fireplace windows and large telescope mirror. The control of crystallization is a key stage in this process. Indeed, lot of properties have to be finely adjusted to fulfil the requirements imposed by the application, including the thermal expansion coefficient, optical transmission, color and transparency.

We will present the evolution of the microstructure at different steps of the ceramming process from the formation of the nuclei (Zr1-xTi1+xO4) to the β-quartz crystals (main LAS phase) and the residual glassy phase by means of analytical TEM and STEM investigations. It will be shown that nuclei are distributed in two distinguished area: in the inner part of LAS crystals and in the residual glassy phase shell around the LAS crystals.

The distribution of elements in the microstructure was analysed by EDX and these investigations will be compared to results acquired by tomographic atom probe analysis. In parallel macroscopic properties like thermal expansion coefficient, high temperature resistance, and various optical properties were measured and the relationship between the microstructure and these properties will be discussed.

Finally, the impact of thermal ageing on the microstructure will be presented.