Kinetics Study on Controlled Crystallization of a Ca2ZnSi2O7 Phase in Materials Obtained from Vitrification of Metallurgical Slag and Recycled Soda Lime Glass
Non isothermal kinetics of a glass obtained from a mixture of 59 wt % of metallurgical slag and 41 wt % of soda lime recycled glass was studied by differential thermal analysis (DTA), x-ray diffraction (XRD) and scanning electron microscopy (SEM). The curves of differential thermal analysis revealed the presence of two exothermic peaks, a major peak at 810 °C and a minor peak at 1085 °C. DRX revealed that the first exothermic peak corresponds to the formation of hardystonite, Ca2ZnSi2O7 and aegirine, NaFe3+Si2O6, while the second minor peak corresponds to the formation of zinc ferrite, ZnFe2O4. The activation energy of the crystallization, Ea, was calculated with the Kissinger equation from DTA data, obtained at different heating rates. In addition, the particle size effect on the kinetics of crystallization was studied. The Avrami factor, n, was calculated with Augis-Bennett method. The values of obtained Ea increase with bigger particle sizes and also the value of n, indicating that for small particles the superficial crystallization mechanism is predominant, while bulk mechanism is preferential on large particles. Obtained materials are suitable for some structural applications.
Pietro VINCENZINI and Michele DONDI
E. I. Cedillo González et al., "Kinetics Study on Controlled Crystallization of a Ca2ZnSi2O7 Phase in Materials Obtained from Vitrification of Metallurgical Slag and Recycled Soda Lime Glass", Advances in Science and Technology, Vol. 68, pp. 114-119, 2010