Effects of Iron Oxide on the Crystallization Kinetics of Baiyunebo Tailing Glass-Ceramics

Abstract

Glass-ceramics in the CaO-MgO-Al₂O₃-SiO₂ system were prepared using Baiyunebo tailing and fly ash as the main raw materials. The effects of iron oxide (Fe₂O₃) on the crystallization kinetics of augite-based glass-ceramics were studied by using differential thermal analysis (DTA), X-ray powder diffraction (XRD), electron backscatter diffraction (EBSD), energy dispersive spectrometer (EDS) and Raman microscopy. The results of Raman and EBSD examinations confirmed the presence of magnetite phase within the glass after nucleation treatment. Augite was the main crystal phase of the studied glass-ceramics. Our result suggested magnetite nuclei to be the starting points of augite crystallization. In addition, the activation energy of crystallization (E_c ) for augite crystal growth, obtained from Kissinger equation, first increased up to a maximum, then decreased with the increase of additional iron oxide, varying between 331 and 426 kJ.mol^–1. The variation of activation energy might be related to the viscosity of glass, which was influenced by the iron oxide content in the glass-ceramics.

Keywords:

• Glass-ceramics
• Baiyunebo tailing
• Crystallization kinetics
• Augite