Effect of Shear Stress on Isothermal Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Slags

Gu, Sijia; Wen, Guangrui; Ding, Zequan; Tang, Ping; Liu, Qiang

doi:10.3390/ma11071085

Cited by 12 publications

(7 citation statements)

References 40 publications

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“…DSC was used to analyze the crystalline fraction of the slag films. The principle of DSC has been described in detail in a previous paper [13]. An HF-200 Heat Flux Simulator was used to obtain the water-quenched slags and the slag films [14].…”

Section: Materials Preparationmentioning

confidence: 99%

Effect of Bubbles on Crystallization Behavior of CaO–SiO2 Based Slags

Wen

Ding

et al. 2019

Metals

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Surface longitudinal cracks are a serious problem and particularly prevalent in the casting of peritectic steel (carbon content between 0.10%C and 0.18%C, non-alloyed). It is usually alleviated by controlling the horizontal heat transfer from the steel shell to the mold through increasing the crystallization performance of slags. In the actual continuous casting process, a large number of bubbles are formed in the molten slags, and the crystallization properties of the mold fluxes are affected by bubbles. Therefore, an investigation of the influence of bubbles on the crystallization performance of mold fluxes was carried out by applying the hot thermocouple technique and it is hoped that surface longitudinal cracks can be solved in this way in the peritectic steel casting process. The continuous cooling transformation (CCT) diagrams and time–temperature transformation (TTT) diagrams were constructed for an analysis of the crystallization kinetics. The results showed that the crystallization ability of mold fluxes was enhanced by adding bubbles through shortening the incubation time of crystallization, increasing the critical cooling rate, and decreasing the activation energy of crystallization. As a result, the crystalline fraction, slag film thickness, and surface roughness of the slag films were improved, but the crystalline phase was not affected by bubbles. With an increase of the bubble content remaining in the molten slag, the growth mechanism of the cuspidine crystal phase changed from a low dimension to a high dimension, and the content of the molten slag’s structure unit (Q1) needed for cuspidine in the molten slag was markedly increased.

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Section: Materials Preparationmentioning

confidence: 99%

Effect of Bubbles on Crystallization Behavior of CaO–SiO2 Based Slags

Wen

Ding

et al. 2019

Metals

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“…Thermogravimetry and differential scanning calorimetry (TG‐DSC) is a kind of general‐purpose standard analytical instrument with high precision, high sensitivity, and good reproducibility, which is considered for testing the weight and heat change of samples during a heating or cooling process with a controlled atmosphere. It is widely used in various fields, [ 21,22 ] such as crystallization temperature, [ 23,24 ] volatilization of carbonate [ 25,26 ] or fluoride, [ 27 ] and re‐crystallization temperature. [ 28 ] Consequently, in this study, TG‐DSC was used to used to evaluate the combustion characteristics of carbon materials.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method for Evaluating the Combustion Characteristics of Carbon Materials and Mold Fluxes

Liang

Wen

et al. 2020

steel research int.

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The combustion characteristic of mold fluxes is extremely important for the high‐quality slabs and the smooth casting process, which is directly determined by the type and content of carbon materials. Herein, the physicochemical properties and combustion characteristics of carbon materials are investigated by field emission scanning electron microscopy, X‐ray diffraction, Brunauer–Emmett–Teller theory, and thermogravimetry (TG) and differential scanning calorimetry (DSC), followed by the influences of carbon materials on the combustion and melting behavior of mold fluxes. The results show that: 1) the fixed carbon content in single‐carbon materials and carbon‐added mold fluxes can be determined by TG curves; 2) the combustion temperature ranges and the combustion reaction time of single‐carbon materials and carbon‐added mold fluxes can be characterized by DSC curves; and 3) the combustion characteristics of carbon are influenced by mold fluxes, leading to a shorter combustion reaction time. The reduction of combustion reaction time for 1# and 2# being 7.5 and 8.2 min is much larger than that of 2.4 min for 3#. Finally, the melting behavior of mold fluxes is influenced by carbon, especially the melting temperature, flowing temperature, and the melting time, showing an increase trend. However, the softening temperature shows little change.

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“…Mold flux is an indispensable material in the continuous casting process. It helps to lubricate steel shell to prevent sticking against the mold surface and control the heat transfer to achieve uniform shell [1][2][3][4][5][6][7]. The stability of the continuous casting process and the surface quality of products are restricted to good performance of the above functions, which are closely related to the physio-chemical properties of the mold flux, such as viscosity, melting temperature, crystallization behavior [4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…The present authors investigated the crystallization of molten mold fluxes containing both B 2 O 3 and TiO 2 and explored the effects of B 2 O 3 and TiO 2 on incubation time for crystallization of molten fluxes [24]. However, besides molten layer, there is glass layer in the gap between steel shell and mold wall [3]. And the crystallization of glassy mold fluxes, i.e.…”

Section: Introductionmentioning

confidence: 99%

Crystallization characteristics of B2O3 and TiO2-bearing glassy fluoride-free mold fluxes

Wang

Shu

Chou

2020

J min metall B Metall

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To explore the effects of TiO2 and/or B2O3 on crystallization of the glassy fluoride-free slag film near the copper mould, the crystallization characteristics of glassy fluoride-free mold fluxes with fluoride being substituted by TiO2 and/or B2O3 were investigated using X- ray diffraction (XRD), scanning electron microscope (SEM) and differential thermal analysis (DTA) techniques. The glass forming ability index (Kgl) of the glassy fluoride-free mold fluxes was studied using Hruby?s method. The XRD and SEM analysis show that Ca2Al2SiO7, CaTiO3 and CaSiO3 are the dominant crystals of this fluoride-free mold fluxes system. With the content of TiO2 increasing from 0 to 7%, the crystallization of Ca2Al2SiO7 and CaSiO3 are inhibited and the formation of CaTiO3 is also weak, so crystallization tendency of the glassy fluoride-free mold fluxes weakens. But as TiO2 content reaches 10%, the crystallization tendency strengthens because of the strong crystallization of CaTiO3. An increase of B2O3 inhibits the crystallization of calcium silicate, so it weakens the crystallization tendency of the glassy fluoride-free mold fluxes. The crystallization processes of the studied fluoride-free mold fluxes correspond to the surface crystallization mechanism. This research provides important reference for further investigation on the heat transfer behavior of the TiO2 and B2O3-bearing slag between copper mould and slab to evaluate the feasibility of B2O3 and TiO2- bearing fluoride-free mold fluxes.

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Effect of Shear Stress on Isothermal Crystallization Behavior of CaO-Al2O3-SiO2-Na2O-CaF2 Slags

Cited by 12 publications

References 40 publications

Effect of Bubbles on Crystallization Behavior of CaO–SiO2 Based Slags

Effect of Bubbles on Crystallization Behavior of CaO–SiO2 Based Slags

A Novel Method for Evaluating the Combustion Characteristics of Carbon Materials and Mold Fluxes

Crystallization characteristics of B2O3 and TiO2-bearing glassy fluoride-free mold fluxes

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