Evaluation of B2O3as replacement for CaF2in CaO–Al2O3based mould flux

Yan, Wei; Chen, W.; Yang, Yindong; Lippold, Carsten; McLean, Alexander

doi:10.1179/1743281215y.0000000062

Cited by 26 publications

(22 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In particular, the wider use of B 2 O 3 fluidizers in the constituents that compose calcium-silicate and calcium-aluminate-based mold fluxes has been implemented for application in high-Al-content steels exhibiting transformation induced plasticity and twinning induced plasticity steels. [4][5][6]8,14,16 In general, fluoride-containing compounds such as CaF 2 and NaF have been widely used as fluidizers in commercial continuous casting mold powders. 1,7,13,16,17 To ensure uniform heat transfer across the copper mold, optimal use of B 2 O 3 in continuous casting mold flux requires a uniform distribution of amorphous and crystalline phases dispersed within the flux layer.…”

Section: Introductionmentioning

confidence: 99%

“…Often known for its glassforming ability in the glass industry, B 2 O 3 in mold fluxes has been known to inhibit crystallization by forming complex boro-silicate structural units, which may not be optimal for steel grades requiring lower heat removal. [4][5][6]8,14,16 In general, fluoride-containing compounds such as CaF 2 and NaF have been widely used as fluidizers in commercial continuous casting mold powders. In the typical silicate-based mold fluxes, CaF 2 and NaF can depolymerize the silicate structural units, leading to a lower viscosity.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Kim

Sohn

2019

J Am Ceram Soc

View full text Add to dashboard Cite

The relationship between the viscosity and structure of B 2 O 3 -containing calciumsilicate-based mold fluxes and the effects of fluidizers including CaF 2 , CaO, and B 2 O 3 on the viscosity and their correlation with the structural aspects were studied using a rheometer with Fourier transformation infrared and Raman spectroscopy.The viscosity decreased with increasing CaF 2 addition up to 28 wt% at a fixed CaO/ SiO 2 ratio of 0.3, which was related to depolymerization. Furthermore, CaF 2 addition also affected the apparent activation energy for viscous flow, which decreased with increasing CaF 2 content to 105.1 from 151.1 kJ/mol. At higher C/S ratios, the viscosity decreased in the presence of greater Ca 2+ and O 2− supplied from CaO, which subsequently increased the activation energy to 149.7 from 122.0 kJ/mol.With regard to the B 2 O 3 -melt, polymerization of the network structure was observed by comparing the B 2 O 3 -free to 4.4 wt% B 2 O 3 content. However, the viscosity was relatively constant with increasing B 2 O 3 addition. However, the viscosity decreased due to greater simplification of the network structure above 4.4 wt% B 2 O 3 . The break temperature decreased with greater B 2 O 3 addition as the crystallization was inhibited. Furthermore, the apparent activation energy decreased as depolymerization of the network structures occurred above 4.4 wt% B 2 O 3 . K E Y W O R D SB 2 O 3 , CaF 2 , CaO/SiO 2 mass ratio, mold flux, network structure, viscosity

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Kim

Sohn

2019

J Am Ceram Soc

View full text Add to dashboard Cite

show abstract

“…As shown in Figure , addition of B 2 O 3 and Na 2 O slightly increases the incubation time of crystallization for slag samples, which means that B 2 O 3 and Na 2 O could decrease crystallization of CaO–Al 2 O 3 –B 2 O 3 based mold fluxes. Yan et al found that B 2 O 3 reduced initial crystallization temperature at the same cooling rate, prolonged the incubation time of crystallization and eventually suppressed crystallization of CaO–Al 2 O 3 based mold flux. Our results are in line with Yan's work.…”

Section: Resultsmentioning

confidence: 99%

“…The researches on fluoride‐free CaO–Al 2 O 3 based mold flux are still limited. Yan et al investigated that the effects of replacing CaF 2 with B 2 O 3 on heat transfer and crystallization characteristics. Most of their mold fluxes contains CaF 2 and only very few fluoride free mold fluxes was investigated.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Properties of Fluorine‐Free Mold Fluxes Based on CaO–Al₂O₃–B₂O₃ System

Kong

Galdino

et al. 2017

steel research int.

View full text Add to dashboard Cite

Fluorine-free mold flux has received ever increasing attentions due to environmental problems cause by fluorine in casting. Fluorine-free mold fluxes based on CaO-Al 2 O 3 -B 2 O 3 systems are developed in the present work. The melting temperatures, viscosities, and crystallization behaviors of CaO-Al 2 O 3 -B 2 O 3 based mold fluxes are investigated. The results show that the melting temperatures decrease with the increasing B 2 O 3 and Na 2 O content, while the melting temperatures of mold fluxes first increase with increasing CaO/Al 2 O 3 mass ratios, and then decrease with further increasing CaO/Al 2 O 3 ratios. The viscosity values of mold fluxes decrease with increasing of B 2 O 3 , Na 2 O content, and CaO/ Al 2 O 3 ratio. The crystallization temperatures of mold fluxes decrease with the increasing B 2 O 3 and Na 2 O, while the crystallization temperature of mold fluxes first increases with increasing CaO/Al 2 O 3 mass ratios, and then decreases with further increasing CaO/Al 2 O 3 ratios. XRD and SEM are used to analyze the sequence of crystallization. Ca 3 Al 2 O 6 crystals are precipitated at first, followed by LiAlO 2 during continuous cooling for all samples, and Ca 3 B 2 O 6 is precipitated finally. It is shown that CaO-Al 2 O 3 -B 2 O 3 based mold flux has a potential to be applied as a kind of F-free mold flux.

show abstract

“…Gao et al [10] used Raman spectroscopy to determine the effect of fluorine on the structure of a CaO-SiO 2 -Al 2 O 3 -Na 2 O-CaF 2 continuous casting mold flux and reported that the number of nonbridging oxygen ions in Si-O and Al-O tetrahedra increased and the degree of polymerization decreased. Yan et al [11] studied the feasibility of using CaO-Al 2 O 3 -based slag to replace CaF 2 with B 2 O 3 and found that B 2 O 3 can inhibit crystallization and control heat transfer. Sasaki et al[12] studied a Na 2 O-NaF-SiO 2 slag system using Raman spectroscopy and a molecular dynamics model.…”

mentioning

confidence: 99%

Effect of CaF2 on the Viscosity and Microstructure of CaO–SiO2–Al2O3 Based Continuous Casting Mold Flux

Wang

Jin

Zhu

et al. 2019

Metals

View full text Add to dashboard Cite

In this study, a CaO–SiO2–Al2O3-based continuous casting mold flux was designed using the FactSage thermodynamics software to determine the composition range of CaF2. The viscosity characteristics of the mold flux were determined using a rotating viscometer. The results show that the constant temperature viscosity at 1300 °C decreases gradually as CaF2 content is increased from 3% to 11% in the CaO–SiO2–Al2O3-based slag. Viscosity is reduced from 0.854 to 0.241 Pa·s, viscous the flow activation energy is reduced from 157.74 to 114.34 kJ·mol−1, and the break temperature is reduced from 1280 to 1180 °C. Furthermore, when the CaF2 content is increased from 3% to 11%, the number of nonbridging fluorine bonds (Al–F structure and Si–F structure) in the melt increases to 287, the number of bridging fluorine bonds (Al–F–Al structure, Si–F–Si structure, and Si–F–Si structure) is only 17, and the network rupture of fluorine ions in the system is larger than the network formation. Consequently, both the degree of polymerization and viscosity are reduced.

show abstract

Evaluation of B₂O₃as replacement for CaF₂in CaO–Al₂O₃based mould flux

Cited by 26 publications

References 27 publications

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Investigation on Properties of Fluorine‐Free Mold Fluxes Based on CaO–Al₂O₃–B₂O₃ System

Effect of CaF2 on the Viscosity and Microstructure of CaO–SiO2–Al2O3 Based Continuous Casting Mold Flux

Contact Info

Product

Resources

About

Evaluation of B2O3as replacement for CaF2in CaO–Al2O3based mould flux

Cited by 26 publications

References 27 publications

Effect of CaF2, B2O3 and the CaO/SiO2 mass ratio on the viscosity and structure of B2O3‐containing calcium‐silicate‐based melts

Effect of CaF2, B2O3 and the CaO/SiO2 mass ratio on the viscosity and structure of B2O3‐containing calcium‐silicate‐based melts

Investigation on Properties of Fluorine‐Free Mold Fluxes Based on CaO–Al2O3–B2O3 System

Effect of CaF2 on the Viscosity and Microstructure of CaO–SiO2–Al2O3 Based Continuous Casting Mold Flux

Contact Info

Product

Resources

About

Evaluation of B₂O₃as replacement for CaF₂in CaO–Al₂O₃based mould flux

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Effect of CaF₂, B₂O₃ and the CaO/SiO₂ mass ratio on the viscosity and structure of B₂O₃‐containing calcium‐silicate‐based melts

Investigation on Properties of Fluorine‐Free Mold Fluxes Based on CaO–Al₂O₃–B₂O₃ System