The non-isothermal devitrification of Na2O · 2 CaO · 3 SiO2 glass has been studied by differential thermal analysis in order to evaluate, from DTA curves, the temperature of maximum nucleation rate, Tm, and the activation energy values, Ec, for crystal growth. The temperature, Tm=580°C, is very close to the glass transition temperature, Tg=570°C, and the value of Ec=78 Kcal mole−1 for the surface crystal growth is nearly the same as the value Ec=89 kcal mole−1 for the bulk crystal growth; both are consistent with the activation energy for viscous flow. It is also pointed out that the nucleation rate—temperature curve and the crystallization rate—temperature curve are partially overlapped.
Nucleation and crystal growth in Na2O*2CaO*3SiO2 glass. A DTA study / A., Marotta; Saiello, Silvana; Branda, Francesco; A., Buri. - In: THERMOCHIMICA ACTA. - ISSN 0040-6031. - ELETTRONICO. - 46:(1981), pp. 123-129.
Nucleation and crystal growth in Na2O*2CaO*3SiO2 glass. A DTA study
SAIELLO, SILVANA;BRANDA, FRANCESCO;
1981
Abstract
The non-isothermal devitrification of Na2O · 2 CaO · 3 SiO2 glass has been studied by differential thermal analysis in order to evaluate, from DTA curves, the temperature of maximum nucleation rate, Tm, and the activation energy values, Ec, for crystal growth. The temperature, Tm=580°C, is very close to the glass transition temperature, Tg=570°C, and the value of Ec=78 Kcal mole−1 for the surface crystal growth is nearly the same as the value Ec=89 kcal mole−1 for the bulk crystal growth; both are consistent with the activation energy for viscous flow. It is also pointed out that the nucleation rate—temperature curve and the crystallization rate—temperature curve are partially overlapped.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
