A Kinetic Study of the Effect of Basicity on the Mold Fluxes Crystallization

Zhou, Lejun; Wang, Wanlin; Ma, Fanjun; Li, Jin; Wei, Juan; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

doi:10.1007/s11663-011-9591-5

Cited by 143 publications

(94 citation statements)

References 14 publications

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“…This result is also in accordance with the findings that the crystallization temperatures of CaO-SiO 2 -CaF 2 -based mold fluxes decrease with the decrease in the mold flux basicity (mass pct CaO/mass pct SiO 2 ). [9,21,22] It is clear from Figure 5(b) that the crystallization temperature of the second crystalline phase CaF 2 in the SiO 2 -free slag is much higher than those in the SiO 2 -containing slags. For CaF 2 -CaOAl 2 O 3 -SiO 2 slags, it appears that increasing SiO 2 addition from 2.8 to 6.8 mass pct has no noticeable effect on the crystallization temperature of the second crystalline phase formed in these slags, as shown in Figure 5(b).…”

Section: B Crystallization Temperatures and Crystallization Ability mentioning

confidence: 96%

“…[8][9][10][11][12][13][14][15] The conventional such mold fluxes contain 70 mass pct (CaO+SiO 2 ), 2 to 6 mass pct Al 2 O 3 , 2 to 10 mass pct Na 2 O(+K 2 O), 0 to 10 mass pct F with varying addition of MgO, TiO 2 , B 2 O 3 , Li 2 O, etc., and basicity (mass pct CaO/mass pct SiO 2 ) of the fluxes ranges from 0.7 to 1.3. [4] In view of the significant difference in the slag chemistry, the crystallization behaviors of ESR type CaF 2 -CaO-Al 2 O 3 -(SiO 2 ) slags should be different from those of the mold fluxes.…”

Section: Introductionmentioning

confidence: 99%

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Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

Shi

Cho

et al. 2015

Metall Mater Trans B

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The crystallization characteristics of CaF 2 -CaO-Al 2 O 3 slags with varying amounts of SiO 2 were experimentally studied. The effects of slag crystallization behaviors on the horizontal heat transfer and lubrication performance in drawing-ingot-type electroslag remelting (ESR) were also evaluated in terms of as-cast ingots surface quality and drawing-ingot operation. The results show that increasing SiO 2 addition from 0 to 6.8 mass pct strongly suppresses the crystallization of ESR type CaF 2 -CaO-Al 2 O 3 slags. The crystallization temperature of the studied slags decreases with the increase in SiO 2 addition. The liquidus temperatures of the slags also show a decreasing trend with increasing SiO 2 content. In CaF 2 -CaO-Al 2 O 3 -(SiO 2 ) slags, faceted 11CaOAE7Al 2 O 3 AECaF 2 crystals precipitate first during continuous cooling of the slag melts, followed by the formation of CaF 2 at lower temperatures. 11CaOAE7Al 2 O 3 AECaF 2 was confirmed to be the dominant crystalline phase in the studied slags. CaF 2 -CaO-Al 2 O 3 slags with a small amount of SiO 2 addition are favorable for providing sound lubrication and horizontal heat transfer in mold for drawing-ingot-type ESR, which consequently bring the improvement in the surface quality of ESR ingot and drawing-ingot operating practice as demonstrated by plant trials.

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Section: B Crystallization Temperatures and Crystallization Ability mentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

Shi

Cho

et al. 2015

Metall Mater Trans B

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“…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.…”

Section: E Effect Of Melt Composition On Crystal Morphologymentioning

confidence: 99%

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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“…In Eq. (1), the volume fraction of crystalline phase, X at a certain holding time and a certain holding temperature could be approximately calculated as follows: 24) . Where AC is the area of crystalline phase and AT is the total area of slag melts.…”

Section: Analysis Of Crystallization Kineticsmentioning

confidence: 99%

Co-modification and Crystalline-control of Ti-bearing Blast Furnace Slags

Sun

Liu

et al. 2015

ISIJ International

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The present paper investigated how the SiO2 and B2O3 additions influenced the crystallization behaviors of Ti-bearing blast furnace (Ti-BF) slags with a purpose of recycling the titanium. Ti-BF slags were co-modified by different SiO2 and B2O3 contents. Isothermal experiments were carried out using a Single Hot Thermocouple Technique (SHTT) to in-situ determine the crystal formation, and accordingly Time Temperature Transformation (TTT) curves were established. The results showed that the small amount of B2O3 addition can efficiently promote the transformation of primary crystalline phase from perovskite to rutile, whereas the precipitation of perovskite was suppressed. The kinetics of precipitation of the crystalline phase was explored and the results indicated that the growth of rod shape rutile was 1-D with the ratecontrolling step of interfacial reaction; whereas the precipitated perovskite presented a 3-D growth style. With the increase of holding time, the nucleation rate of the formed crystals including rutile and perovskite became smaller.

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A Kinetic Study of the Effect of Basicity on the Mold Fluxes Crystallization

Cited by 143 publications

References 14 publications

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

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

Co-modification and Crystalline-control of Ti-bearing Blast Furnace Slags

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