A STUDY ON THE MECHANISM OF CRYSTAL-GROWTH IN THE PROCESS OF CRYSTALLIZATION OF GLASSES

This paper investigates the CaO-Al2O3-SiO2 system glass. When the glas ses were heat treated at different temperatures and times, they crysta llized from the surface. The main crystals were dendrites of anorthite (CaAl2Si2O8). The morphology of crystallization was observed using sc anning electron microscopy, and the crystal size was measured by optic al microscopy. It was found that the growth of anorthite (CaAl2Si2O8) crystals was diffusion controlled. The apparent activation energy for crystal growth was about 581 kJ/mol. The rate of crystal growth was no t constant during the growth process; the rate was highest at the begi nning of crystallization and gradually decreased with increasing time. The higher the temperature, the less time required to complete crysta l growth. The total process of diffusion may be determined by the diff usion rate of Ca2+. 1998 Elsevier Science Ltd.