Ceramics-Silikáty 55, (2) 188 - 194 (2011) |
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CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS
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Ghasemzadeh M. 1, Nemati A. 2, Nozad A. 3,
Hamnabard Z. 3,
Baghshahi S. 4
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1 Deptartment of Materials Eng., Science & Research Branch,
Islamic Azad University, Tehran, Iran
2 Dept. of Materials Sci. & Eng., Sharif University of Technology, Tehran, Iran
3 Ceramic Group, Material Research School, Karaj, Iran
4 Faculty of Engineering, Imam Khomeini International University, Qazvin, Iran
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Keywords: Crystallization kinetics, Activation energies, Glass ceramics, Microstructure, Phlogopite
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The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO₂–Al₂O₃–K₂O–B₂O₃–F system, was studied
by substitution of Li₂O for K₂O in the glass composition. DTA, XRD and SEM were used for the study of crystallization
behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was
investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The
crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization
mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was
bulk crystallization for base glass and the sample with addition of Li₂O. Non-isothermal DTA experiments showed that the
crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of
Li₂O was changed to the range of 317-322 KJ/mol. |
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