کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10639993 | 995864 | 2005 | 5 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Mullite crystallization mechanism obtained from kinetic parameters determination for seeded and non-seeded gel
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موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Mullite crystallization mechanism obtained from kinetic parameters determination for seeded and non-seeded gel Mullite crystallization mechanism obtained from kinetic parameters determination for seeded and non-seeded gel](/preview/png/10639993.png)
چکیده انگلیسی
Mullite crystallization kinetics was studied using a non-isothermal method. The mullite crystallization parameters obtained from seeded gels were compared with those obtained from non-seeded gels. The phase evolution was studied by X-ray diffraction (XRD) and the thermal events associated to heating treatment by differential thermal analysis (DTA). The crystallization kinetic parameters were obtained using the methodology developed by R.A. Ligero, which is based on Johnson-Mehl-Avrami (JMA) kinetic model. The Avrami exponent (1.9), the apparent activation energy (980Â kJ/mol) and the rate constant (3.68Â ÃÂ 1030Â sâ1) were determined by this model, for both seeded and non-seeded processes, resulting in similar values for each parameter. Based on the apparent activation energy and rate constant values, one should conclude that mullite crystallization is not controlled by nucleation. On the other hand, Avrami exponent â¼2 is an indicative that the process is controlled by the nucleation step. These controversies are discussed in this paper, based on experimental procedure, model limitation and literature information.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: B - Volume 122, Issue 3, 25 September 2005, Pages 169-173
Journal: Materials Science and Engineering: B - Volume 122, Issue 3, 25 September 2005, Pages 169-173
نویسندگان
A.L. Campos, E.Y. Kawachi, T.C. Oliveira, G.P. Thim,