DIRECTED CRYSTALLIZATION OF CLASSES IN THE SYSTEM SIO2-CAO-MGO+(ZNO+LI2O) NUCLEATED WITH MOO3 AND WO3

In the glass-crystalline materials obtained through the directed nucle ation, the main principal is to determine the optimum quantity of nucl eating catalyst needed to bring about fine-crystalline phase in the gl ass during heating. The methods of choosing the catalyst are very well known, but sometimes some of them are labour-consuming and complicate d equipment are demanded. In this work a simple and quick method of ch oosing the catalyst to produce glass-crystalline materials was examine d. The method is elaborated on the DTA analysis curves basis. Investig ations were made on the system SiO2-CaO-MgO+(ZnO+Li2O) nucleated with molybdenum and tungsten oxides. Influence of different amounts of cata lyst on crystallization process of different particle size glass sampl es was determined using characteristic points on DTA curve.