Crystallisation studies on site saturated lithium aluminosilicate (LAS) glass

Available sites for nucleation has to reach saturated condition that is a primary validity criterion for employing conventional thermo-analytical (TA) methods. Non-isothermal DSC and TA methods were employed to determine the crystallisation parameters of site-saturated lithium aluminosilicate (LAS) glass. Activation energy of crystallisation for a thermally stable LAS composition was determined after prenucleation process and it was found to be 371 +/- 14 kJ/mol. A heat treatment programme for controlled crystallisation process was designed to result a transparent ( > 80%), nanocrystalline, low expansion (coefficient of thermal expansion - 0.31 ppm/K between - 60 to + 60 degrees C) glass-ceramic. Crystal growth at 1048 K was determined to be in range 2.56-3.53 x 10(-11) m/s and viscosity of glass near the growth front was predicted to vary between 1.28 x 10(5) and 2.82 x 105N s m(-2).