SiO2-Al2O3-CaO glass-ceramics: Effects of CaF2 on crystallization, microstructure and properties

The effects of fluorine content on the nucleation and crystallization behavior of SiO2-Al2O3-CaO glass ceramics system have been investigated. The crystalline phases were determined by X-ray diffraction (XRD). The crystallization kinetics was determined by differential thermal analysis (DTA). The microstructures were examined by using scanning electron microscope (SEM). Fourier transformed infrared spectra (FTIR) analysis was used to study the glass structure. The results showed that by increasing the fluorine content, both the crystallization peak temperature (T-p) and activation energy (E) decreased. Wollastonite, anorthite and gehlenite are the main crystalline phases that exist in the glass ceramics system. The study shows that fluorine promoted initial crystallization of glass and can be used as an effective nucleating agent in the SiO2-Al2O3-CaO system. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.