Crystallization behavior in the glass system MgO-Al2O3-SiO2:: influence of CeO2 addition

For the investigation of the crystallization behavior of the glass with the composition 2MgO-2Al(2)O(3)-5SiO(2), corresponding to stoichiometric cordierite, according to the addition of CeO2 as a flux the maximum nucleation and crystal growth rates were determined by observing the microstructure of the crystallized glass with scanning electron microscopy (SEM). The crystallization mechanism was also studied by an isothermal method using differential thermal analysis (DTA). The glass transition temperature (T-g) decreased with the CeO2 addition and only a-cordierite was precipitated as a main crystal phase without mu -cordierite for all heat treated glasses containing CeO2. The maximum nucleation and crystal growth rates were 2.4 mum(-3) h(-1) at 800 degreesC and 0.3 mum h(-1) at 915 degreesC, respectively. The activation energy value E obtained from isothermal method was 88.9 +/- 9.1 kcal mol(-1), and the Avrami constant n was 1.08 +/- 0.27, which indicates a surface growth mechanism through an interface reaction. (C) 2001 Elsevier Science B.V. All rights reserved.