Effect of heat treatment on the crystallization toughening of tailing-derived glass-ceramics

The effect of heat treatment to a parent glass of the composition CaO-MgO-Al2O3-SiO2 (CMAS) on the course of crystallization and properties of the Bayan Obo east mine tailing glass-ceramics is examined. The crystallization behavior, phase composition, morphology and structure of glass-ceramics are characterized. The results indicate that the phases formed in the glass-ceramics are augite and the initial nucleation phases are magnetite, which can be proved by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning transmission electron microscope (STEM). Heat treatment plays a significant role in improving the crystallization process, fracture characteristics, modulus and bending strength. All of these properties reach a maximum for the fully crystallized glass-ceramic. Scanning electron microscope (SEM) and atomic force microscope (AFM) are used to reveal the topography of the fracture surfaces. The intergranular fracture can be observed on the fracture surface.