کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1611845 | 1516302 | 2014 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Crystallization kinetics of a barium-zinc borosilicate glass by a non-isothermal method
ترجمه فارسی عنوان
سینتیک بلوری شدن یک شیشه بوروسیلیکات باریم روی با استفاده از روش غیر ایزوترمال
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کلمات کلیدی
تجزیه و تحلیل حرارتی دیفرانسیل عینک بوروسیلیکات، فرایند غیر ایزوترمال، سینتیک بلوری شدن،
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فلزات و آلیاژها
چکیده انگلیسی
The crystallization kinetics of a glass with a molar composition 40BaO-20ZnO-30B2O3-10SiO2 was investigated. The kinetic parameters, activation energy for crystallization (Ec) and Avrami exponent (n), were evaluated under non-isothermal conditions using the results obtained by differential thermal analysis (DTA) performed at different heating rates. DTA curves exhibited two overlapping exothermic peaks associated with the crystallization of the glass. Barium borate (BaB4O7) was the first crystalline phase to be formed and it was followed by the formation of barium zinc silicate (BaZnSiO4), as identified by XRD. For the first exothermic peak, when the fraction of crystallization (Ï) increased from 0.1 to 0.9, the local activation energy (Ec(Ï)) decreased from 700 to 500Â kJ/mol, while for the second exothermic peak, Ec(Ï) slightly increased from 490 to 570Â kJ/mol. For the range of 0.1Â <Â ÏÂ <Â 0.9, the local Avrami exponent (n(Ï)) increased from â¼1 to 1.4 for the first exothermic peak and it decreased from â¼1.7 to 1.4 for the second exothermic peak. Observation by SEM of the microstructure of sintered glass samples revealed that crystallization started at the surface of glass particles, with growth of lamellar crystallites, that together with some quasi-spherical nano-sized crystallites progressed towards the inside of the glass at the highest sintering temperatures. The change of the local activation energy with the fraction of crystallization suggested that a multi-step kinetic reaction took place during sintering and crystallization of the glass.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Alloys and Compounds - Volume 591, 5 April 2014, Pages 268-274
Journal: Journal of Alloys and Compounds - Volume 591, 5 April 2014, Pages 268-274
نویسندگان
A.A.S. Lopes, R.C.C. Monteiro, R.S. Soares, M.M.R.A. Lima, M.H.V. Fernandes,