Crystallization Kinetics of CaO-SiO₂(CaO/SiO₂=1)-TiO₂-10 mass%B₂O₃ Glassy Slag by Differential Thermal Analysis

Abstract

Crystallization characteristics of the CaO-SiO2-TiO2-10%B2O3 glassy slag at w(CaO)/w(SiO2)=1 have been studied by Differential Thermal Analysis (DTA) and Matusita-Sakka method. Crystallization products have been distinguished by employing X-ray diffraction (XRD) and Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy (SEM-EDS). As the TiO2 content is within 10-18%, the crystal phase precipitated is mainly CaSiO3, and the effective activation energies for crystal growth increase with the increase of TiO2 content. Crystallization mechanism for CaSiO3 shifted from surface crystallization to onedimensional growth with increase of TiO2. As the TiO2 content in slag further increases to 22% and 26%, CaTiSiO5 becomes the predominant crystal phase precipitated, and the effective activation energies for crystal growth decrease with the increase of TiO2 content. Crystallization mechanism for CaTiSiO5 is mainly surface crystallization. Therefore, with the increase of TiO2 content, the crystallization ability of the CaO-SiO2-TiO2-10%B2O3 glass system decreases initially and then increases.

Effects of MoO3 + C on Crystallization and Radiative Heat Transfer of CaO–SiO2–B2O3-Based Glassy Fluoride-Free Mold Fluxes

“…Therefore, the firstly precipitated crystals should be CaSiO 3 . In our previous work on the crystallization of CaO-SiO 2 -B 2 O 3 [15], the crystallization product was also CaSiO 3 , which is in line with the present work. It could be also seen that the crystalline peaks in the XRD pattern of the sample Metals 2019, 9, 516 8 of 13 with MoO 3 = 2% were much sharper than those of the Mo-free sample.…”

“…Therefore, the firstly precipitated crystals should be CaSiO3. In our previous work on the crystallization of CaO-SiO2-B2O3 [15], the crystallization product was also CaSiO3, which is in line The bulk Mo-free sample and the sample with MoO 3 = 2% were heated at the crystallization temperature determined by DSC for 2 h and quenched. The XRD patterns for samples are shown in Figure 6.…”

“…All these indicate that the main crystallization mechanism for Mo-free samples could be surface crystallization. Surface crystallization was frequently found to be the crystallization mechanism for glass [32] and glassy mold fluxes [15,33]. Wang et al [33] investigated the crystallization kinetic of glassy mold fluxes with different TiO 2 contents and suggested that the crystallization mechanism for all samples should be surface crystallization.…”

“…Accordingly, fluoride-free mold fluxes have received great attention in recent years. CaO-SiO 2 -TiO 2 -based mold fluxes [13][14][15] are considered to be potential Metals 2019, 9,516 2 of 13 fluoride mold fluxes to replace traditional mold fluxes, with CaTiO 3 and CaTiSiO 5 being substitutes for cuspidine in mold fluxes. However, the lubrication functions of CaO-SiO 2 -TiO 2 -based mold fluxes still need to be improved [16].…”

Control of Crystal Morphology for Mold Flux During High-Aluminum AHSS Continuous Casting Process

“…In order to control the faceted crystal morphology in the mold flux, the favorable Jackson a factor for the primary crystal should be selected firstly, and then the relative lower supercooling of crystallization should be taken into consideration. Many investigations [14,16,[39][40][41] have confirmed the supercooling of crystallization is related to the activation energy of crystallization. Our previous works have investigated their relations both in lime-silica-based [16,37] and lime-alumina-based [14] mold fluxes.…”