Crystallization Behaviors of Mold Fluxes Containing Li&lt;sub&gt;2&lt;/sub&gt;O Using Single Hot Thermocouple Technique

Liu, Hui; Wen, Guangrui; Tang, Ping

doi:10.2355/isijinternational.49.843

Cited by 43 publications

(26 citation statements)

References 36 publications

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“…In addition, it was confirmed by Kim et al measurement that the melt viscosity decreased by adding a small amount of Li 2 O into mold flux. [12] Also, experimental results of Liu et al [38] demonstrated that more faceted crystal precipitated by increasing Li 2 O content in mold fluxes within a reasonable amount, which is in accordance with our present findings.…”

Section: E Effect Of Melt Composition On Crystal Morphologysupporting

confidence: 82%

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

Guo

Seo

Shi

et al. 2016

Metall Mater Trans B

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In the present manuscript, the efforts to control the crystal morphology are carried out aiming at improving the lubrication of lime-alumina-based mold flux for casting advanced high-strength steel with high aluminum. Jackson a factors for crystals of melt crystallization in multi-component mold fluxes are established and reasonably evaluated by applying thermodynamic databases to understand the crystal morphology control both in lime-alumina-based and lime-silica-based mold fluxes. The results show that Jackson a factor and supercooling are the most critical factors to determine the crystal morphology in a mold flux. Crystals precipitating in mold fluxes appear with different morphologies due to their different Jackson a factors and are likely to be more faceted with higher Jackson a factor. In addition, there is a critical supercooling degree for crystal morphology dendritic transition. When the supercooling over the critical value, the crystals transform from faceted shape to dendritic ones in morphology as the kinetic roughening occurs. Typically, the critical supercooling degrees for cuspidine dendritic transition in the lime-silica-based mold fluxes are evaluated to be between 0.05 and 0.06. Finally, addition of a small amount of Li 2 O in the mold flux can increase the Jackson a factor and decrease the supercooling for cuspidine precipitation; thus, it is favorable to enhance a faceted cuspidine crystal.

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Section: E Effect Of Melt Composition On Crystal Morphologysupporting

confidence: 82%

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

Guo

Seo

Shi

et al. 2016

Metall Mater Trans B

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“…[22][23][24] The increasing use of differential thermal analysis (DTA) or differential scanning calorimetry (DSC) at non-isothermal mode has, however, required reliable methods to deal with non-isothermal kinetics. Many researchers have proposed some methods on non-isothermal crystallization kinetics.…”

Section: Crystallization Kineticsmentioning

confidence: 99%

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

2015

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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.

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“…This back-of-the-envelope calculation can reveal the amount of energy generated by the rotating rod in the present study. The densities of calcium silicate-based melts are known to be in the order of ~10 6 g/m 3 , thus the molar volume should be in the range of 10 -5 m 3 /mol, depending on the system. [34][35][36][37] Therefore, it would be assumed that the energy generated by the rotating rod would be in the order of 10 -4 J/mol, which is extremely small and therefore not sufficient to overcome the activation energy of crystallization that in on the order of several tens to hundreds of kJ/ mol.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

“…Therefore, numerous researchers have adopted various methods, including hot-thermocouple, [1][2][3][4] differential thermal analysis, [5][6][7][8][9][10] heat-treatment using a crucible and furnace, 11,12) among others, [13][14][15] to study the crystallization behavior of super-cooled slags and fluxes. However, most of these studies concerned the crystallization behavior of oxides at rest in crucibles or other containers, despite the fact that slags and fluxes are generally handled not only in the liquid-solid coexistence region, but also under a significant shear stress field created by agitation, stirring, or sliding in converters and continuous casting molds.…”

Section: Introductionmentioning

confidence: 99%

Effect of Agitation on Crystallization Behavior of CaO^|^ndash;SiO2^|^ndash;R2O (R = Li, Na, or K) System Characterized by Electrical Capacitance Measurement

et al. 2012

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The effect of agitation on the crystallization behavior of molten 50CaO-50SiO2 and 45CaO-45SiO2-10R2O (R = Li, Na, or K, mol%) fluxes were systematically investigated by the measurement of their electrical capacitance over a wide temperature range from liquid region to well below the liquidus temperature. It is well known that the electrical capacitance of liquids is generally much higher than that of solids owing to the differences in their respective polarization mechanisms. These differences were exploited as a sensitive indicator of the crystallization of molten calcium silicates in an experimental furnace equipped with an electrical capacitance measuring system. The system comprised a Pt-based alloy crucible and a rotating rod that allowed evaluation of the effect of agitation generated by the rod, connected to a capacitance meter (LCR meter).As expected, at a particular temperature, the electrical capacitance of the molten calcium silicates underwent a precipitous decrease by roughly three orders of magnitude, which was dependent on the chemical composition. This indicated the presence of crystallization and this was confirmed by corresponding microstructural characterization. It was also found that, for the measurements acquired with rotating rod agitation, the temperatures at which the capacitance underwent the sharp decrease were higher than that identified without the agitation. This suggests that the agitation effect induced by the rotating rod accelerates the crystallization of molten calcium silicates.

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Crystallization Behaviors of Mold Fluxes Containing Li<sub>2</sub>O Using Single Hot Thermocouple Technique

Cited by 43 publications

References 36 publications

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

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

Crystallization Kinetics of CaO-SiO<sub>2</sub>(CaO/SiO<sub>2</sub>=1)-TiO<sub>2</sub>-10 mass%B<sub>2</sub>O<sub>3</sub> Glassy Slag by Differential Thermal Analysis

Effect of Agitation on Crystallization Behavior of CaO^|^ndash;SiO2^|^ndash;R2O (R = Li, Na, or K) System Characterized by Electrical Capacitance Measurement

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