Effect of Na2O and B2O3 on the Crystallization Behavior of Low Fluorine Mold Fluxes for Casting Medium Carbon Steels

Wei, Juan; Wang, Wanlin; Zhou, Lejun; Huang, Daoyuan; Zhao, Huan; Ma, Fanjun

doi:10.1007/s11663-013-9957-y

Cited by 55 publications

(43 citation statements)

References 25 publications

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“…[25][26][27][28] And, it was divided into two parts; the first part is about melting and heat transfer behaviors; while the second part is focused on the study of viscosity and crystallization behavior of F-free mold fluxes for medium carbon steels continuous casting. This is the second part with the aim to investigate the viscosity and crystallization behavior of F-free mold fluxes.…”

Section: 24)mentioning

confidence: 99%

“…The reason for that is because the CaO, Na 2 O, and Li 2 O are network modifiers in molten silicate structure system, which can provide O 2 − to break down the Bridging Oxygen Si-O-Si chain into Non Bridging Oxygen Si-O, and then simplify the silicate structure and lower the viscosity and breaking temperature of F-free mold flux. 26,27) Therefore, the decrease of the Na 2 O, Li 2 O contents and basicity would lower the rheological property of molten mold flux. Otherwise, the viscosity at the temperature of 1 573 K (1 300°C) and the breaking temperature of Sample E continued to increase from 0.212 Pa•s to 0.256 Pa•s and from 1 495 K (1 222°C) to 1 507 K (1 234°C), with further reduction of about 2% Na 2 O and 2% B 2 O 3 contents based on Sample D, as both B 2 O 3 and Na 2 O tend to decrease the viscosity of mold flux.…”

Section: )mentioning

confidence: 99%

“…Otherwise, the viscosity at the temperature of 1 573 K (1 300°C) and the breaking temperature of Sample E continued to increase from 0.212 Pa•s to 0.256 Pa•s and from 1 495 K (1 222°C) to 1 507 K (1 234°C), with further reduction of about 2% Na 2 O and 2% B 2 O 3 contents based on Sample D, as both B 2 O 3 and Na 2 O tend to decrease the viscosity of mold flux. 13,26,27) In order to compare the different rheology behaviors of mold fluxes, the plots of lnη versus 1/(RT) for the benchmark Sample A and four designed F-free mold fluxes during different temperature zone were shown in Fig. 6, where Fig.…”

Section: )mentioning

confidence: 99%

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Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

2015

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Viscosity and crystallization are essential properties to characterize the lubrication and heat transfer performances of mold flux. Therefore, in this paper, the viscosity and crystallization behaviors of conventional F-containing commercial mold flux and newly designed F-free mold fluxes were investigated by using rotating cylinder method and Single/Double Hot Thermocouple Technique (SHTT/DHTT). Results shows that the viscosities of designed F-free mold fluxes are close to the F-containing mold flux; and the crystallization temperatures of F-free mold fluxes increases with the increase of basicity and Na 2 O/Li 2 O content; while it decreases with the increase of cooling rate and the addition of B 2 O 3 . The final steady state structure of F-free mold fluxes during the DHTT tests shows it is composed of a major crystalline and a thin liquid layer (5.42-7.2%) without glass phase. The results of XRD indicate that the main crystalline phases formed in designed F-free mold fluxes were calcium borosilicate (Ca 11

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Section: 24)mentioning

confidence: 99%

Section: )mentioning

confidence: 99%

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confidence: 99%

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Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

2015

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“…It is found that the size of the solid solution at the cooling rate of 2.5 K/min is larger than that of 10 K/min. This may because the molten slag viscosity becomes larger with the addition of cooling rate, 19,20) which makes it more difficult for the transportation of molten species. Thus it requires a larger driving force to initiate the crystallization, and results in a larger undercooling.…”

Section: Morphology and Size Of The Solid Solutionmentioning

confidence: 99%

Effect of Na2O and B2O3 on the Distribution of P2O5 between Solid Solution and Liquid Phases Slag

et al. 2014

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With the development of multiphase slag system for hot-metal treatment to achieve better dephosphorization efficiency, it is very important to improve the distribution ratio of P2O5 between the solid solution (2CaO·SiO2-3CaO·P2O5) and liquid phase slag. This study was carried out to investigate the effects of Na2O and B2O3 on P2O5 distribution ratio and morphologies of corresponding solid solutions in CaO-SiO2-Fe2O3-P2O5 slag system. The results indicated that the distribution ratio of P2O5 would be improved with the increase of Na2O content due to the formation of (2CaO·SiO2-Na2O·2CaO·P2O5) solid solution with a similar morphology as that of reference solid solution (2CaO·SiO2-3CaO·P2O5) in the reference slag. While B2O3 plays an opposite role, it would not only reduce the phosphorus distribution ratio, but also change the morphology of its corresponding solid solution due to the formation of complex solid solution (2CaO·SiO2-Ca9.93(P5.84B0.16O24) (B0.67O1.79)). Besides, the effect of cooling rate on the size of the solid solution was also studied. It would provide an instructive way for the design of multiphase slag for hot metal treatment.

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“…14 SiO 4 , was promoted at high temperature with high CaO/SiO 2 ratio, which is in accordance with the thermodynamic expectation. Wei et al 39) in their study of low fluorine-containing mould fluxes suggested that Ca 11 Si 4 B 2 O 22 was a possible substitution for cuspidine due to their similar melting properties. The melting temperature of Ca 11 Si 4 B 2 O 22 is 1 420°C 40) which is close to the melting temperature of cuspidine (1 407°C 39,41) ).…”

Section: Precipitated Phases In the Process Of Flux Solidifi-mentioning

confidence: 99%

In-situ Study of Crystallisation Behaviour of CaO–SiO2–Na2O–B2O3–TiO2–Al2O3–MgO–Li2O Fluorine-free Mould Fluxes with Different CaO/SiO2 Ratios

et al. 2016

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The increasing environmental concern for the fluorine emission in steel continuous casting makes the development of fluorine-free mould fluxes imperative. The main challenge in the development of fluorinefree mould fluxes is controlling heat transfer rate which is closely related to the crystallisation behaviour of mould fluxes. In this study, the crystallisation behaviour of CaO-SiO 2 -Na 2 O-B 2 O 3 -TiO 2 -Al 2 O 3 -MgO-Li 2 O fluorine-free mould fluxes with CaO/SiO 2 mass ratios from 0.9 to 1.2 was examined using single hot thermocouple technique (SHTT) and double hot thermocouple technique (DHTT). Continuous cooling transformation (CCT) and time-temperature transformation (TTT) diagrams developed using SHTT showed that the crystallisation temperature increased and the incubation time decreased with the increase of CaO/SiO 2 ratio. DHTT was used to simulate the temperature gradient between copper mould and strand in steel continuous casting. Analysis of the crystallinity evolution in the simulated temperature field showed an increased crystallinity of fluxes with the increase of the CaO/SiO 2 ratio at certain times. The crystal phases and crystal morphologies formed in different conditions were analysed by X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray energy dispersive spectroscopy (EDS

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Effect of Na2O and B2O3 on the Crystallization Behavior of Low Fluorine Mold Fluxes for Casting Medium Carbon Steels

Cited by 55 publications

References 25 publications

Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

Effect of Na2O and B2O3 on the Distribution of P2O5 between Solid Solution and Liquid Phases Slag

<i>In-situ</i> Study of Crystallisation Behaviour of CaO–SiO<sub>2</sub>–Na<sub>2</sub>O–B<sub>2</sub>O<sub>3</sub>–TiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub>–MgO–Li<sub>2</sub>O Fluorine-free Mould Fluxes with Different CaO/SiO<sub>2</sub> Ratios

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