The application of differential thermal analysis to the study of isothermal and non-isothermal crystallization kinetics of coal fly ash based glasses


Erol M. M. , KUCUKBAYRAK S., ERSOY-MERICBOYU A.

JOURNAL OF NON-CRYSTALLINE SOLIDS, cilt.355, ss.569-576, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 355 Konu: 9
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1016/j.jnoncrysol.2009.01.023
  • Dergi Adı: JOURNAL OF NON-CRYSTALLINE SOLIDS
  • Sayfa Sayıları: ss.569-576

Özet

The crystallization kinetics of glasses obtained from coal fly ash was investigated by both isothermal and non-isothermal methods using differential thermal analysis (DTA) data. In DTA experiments, glass samples having coarse(800-1000 mu m) and fine (<180 mu m) particle sizes were used and the results were compared. The Avrami exponent (n) was calculated by means of Johnson-Mehl-Avrami (JMA) and Ozawa equations. Calculated kinetic parameters indicated that the appropriate crystallization mechanisms were bulk and surface crystallization for coarse and fine particles, respectively. Isothermal and non-isothermal DTA experiments showed that the crystallization activation energies of coarse glasses are changed in the range of 444-578 kJ/mol, while the crystallization activation energies of fine glasses are changed in the range of 610-662 kJ/mol. It was found that crystallization activation energies of fine glasses are higher than those of the coarse glasses. Results showed that isothermal and non-isothermal crystallization kinetics of glasses produced from coal fly ash is in agreement within the experimental error. (C) 2009 Elsevier B.V. All rights reserved.