Study on Isothermal Crystallization Kinetics of Mica Glass Ceramics

The isothermal crystallization kinetics of mica-containing glass ceramics with addition of TiO2 asnucleation agent was investigated by XRD, SEM and DTA. Two distinct crystallization exotherm peaksin the DTA curve were observed and resolved corresponding to the initial formation of MgTi2O5,followed by the formation of KMg3AlSi3O10F2, confirmed by X-ray diffeaction analysis (XRD). By usingJohnson-Mehl-Avrami equation, the activation energics for precipitation of MgTi2O5 and mica crystalswere enaluated and the crystallization mecjanism of mica was analyzcd. The results indicated that thegrowth of KMg3AlSi3O10F2 is a two-dimensional process, controlled by the crystal-glass interface reaction.The average values of activation energies are 242kJ/mol and 265kJ/mol corresponding to that of MgTi2O5and mica crystalized out of the glass, respectively