Time-temperature-transformation diagrams for crystallization of the oxyfluoride glass system

Abstract

Isothermal crystallization studies were performed on the glass 37.26SiO2-28.11Al2O3-7.73CaO-26.89CaF2-4.5K2O (wt%) in the crystallization region between the glass transition (Tg) and end of crystallization temperature (Tf), resulting in a time-temperature-transformation (T.T.T.) diagram for crystallization. The crystallized fraction calculated by “Ohlberg-Strickler” method. By fitting Avrami curves on experimental data kinetic properties of isothermal crystallization of CaF2 has been determined. It is concluded that the crystallization of the mentioned glass is a process controlled by Avrami nucleation and three-dimensional diffusion controlled growth. The (T.T.T.) ‘‘C’’ shape diagrams with a nose at 690 °C resulted in from fitted Avrami “S” shapes Diagrams.