Preliminary Study About Crystallization of Glasses Belonging to Na2O-SiO2 System.

Crystallization kinetics of three glasses belonging to Na//2O-SiO//2 system has been studied, verifing that it proceeds through a mechanism of random nucleation and crystal growth described by Avrami-Johnson-Mehl equation. It has been also observed that glass composition acts on activation energy of the crytallization process, increasing when alkalies contents rise, and on microhardness, decreasing when alkalies contents rise.