Effect of nucleation temperatures and time on crystallization behavior and properties of Li2O-Al2O3-SiO2 glasses

The crystallization behavior of Li2O-Al2O3-SiO2 glasses samples nucleated at different temperature and time (745 degrees C/2 h, 745 degrees C/6 h and 760 degrees C/6 h) was investigated by DTA, XRD and SEM. After nucleated at 745 degrees C for 2 and 6 h, the Avrami constants for the glass samples were 3.5-3.6 and activation energies of crystal growth were 276 +/- 3 and 280 +/- 5 kJ mol(-1). The Avrami constant was 2.8 and activation energy of crystal growth was 302 +/- 6 kJ mol(-1) for samples nucleated at 760 degrees C for 6 h. The crystallized phase was identified as h-quartz solid solution and SEM observations indicated that glass-ceramic samples have fine grained microstructure which indicates bulk crystallization. With increasing nucleation temperature to 760 degrees C, the grain size increased and the values of flexural strength, hardness and fracture toughness decreased. (c) 2005 Elsevier B.V. All rights reserved.