云母微晶玻璃等温转变动力学的研究

本文对以TiO₂为晶核剂的云母微晶玻璃等温析品转变进行了研究，发现玻璃的差热分析（DTA）曲线上出现了两个析晶放热峰，X光衍射分析（XRD）表明，在这两个析晶峰温度下从玻璃中分别析出了钛酸镁（MgTi₂O₅）和云母（KMg₃AlSi₃O₁₀F₂）晶体.用差热分析测定了玻璃等温析晶活化能和晶体的生长指数．玻璃析出钛酸镁和云母的活化能分别为242kJ／mol和265kJ／mol．云母晶体以二维方式生长，生长过程受界面过程控制.

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