Influence of CaF<sub>2</sub>on viscosity of aluminosilicate melts

Zhang, G-H; Chou, Kuo‐Chih

doi:10.1179/1743281212y.0000000055

Cited by 33 publications

(18 citation statements)

References 35 publications

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“…Shahbazian 17) examined the effect of CaF 2 on the viscosity of CaO-FeO-SiO 2 -CaF 2 system in the temperature range of 1 435-1 749 K and obtained the similar variation trend. As many researchers have pointed out, 14,15,18) the decrease of viscosity with CaF 2 addition may suggest that the CaF 2 plays the role of network modifier in silicate slags to break the silicate network. It was also noteworthy in Fig.…”

Section: Viscosity Measurementmentioning

confidence: 99%

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

et al. 2016

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The role of fluorine in the CaO-SiO 2 -MgO-Al 2 O 3 -Fe t O steelmaking slags was investigated through analyzing the viscous flow and crystallization behaviors of the slags. It was found that the viscosity decreased with increasing CaF 2 content, which resulted from the decrease of the degree of polymerization (DOP) of the structures, as proved by O 1s X-ray photoelectron spectroscopy (XPS) and magic angular spinning nuclear magnetic resonance (MAS-NMR) analysis. The continuous cooling transformation (CCT) diagrams of the primary crystals were also constructed. The results showed that CaF 2 addition promoted the transformation of the primary crystal from spinel (MgFe 2 O 4 ) to flourapatite (Ca 5 (PO 4 ) 3 F), which was beneficial to the further enrichment of phosphorus. According to 19 F MAS-NMR results, F − ions mainly coordinate with Ca 2 + ions to form Ca-F bond. Furthermore, considering the greater stability of P-O-Ca than that of Si-OCa bonds, most of the F − ions behave as F-Ca-O-P band, which thus enhanced the formation of Ca 5 (PO 4 ) 3 F. Additionally, the non-isothermal crystallization kinetics was further analyzed and the activation energy for the primary crystal growth was derived.

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Section: Viscosity Measurementmentioning

confidence: 99%

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

et al. 2016

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“…49) However, at the present time the reader will have to use a number of models to calculate the viscosities of different slag types. The slag viscosity model proposed by Zhang et al, 52) looks to be an attractive option (and covers slags based on calcium aluminates) but at the present time does not include B 2 O 3 additions.…”

Section: Discussionmentioning

confidence: 99%

“…48) Although such calculated values are useful, the data would have wider applicability if they were incorporated into a more global model. The model to calculate viscosities of slags due to Zhang et al 52) covers the compositional range of the different types of mould slags covered here but does not contain B 2 O 3 at the present time. However, there are virtually no property data for some properties like density, surface tension and thermal conductivity.…”

Section: Properties Of Mould Slagsmentioning

confidence: 99%

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 2 Specialist Mould Powders

Mills

2016

ISIJ International

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In Part 1, the thermo-physical properties of conventional mould slags used in the continuous casting of steel were reviewed. In Part 2, the properties of mould slags used in specialised continuous casting are collated and examined. The following types of slag have been studied (i) Fluoride-free (ii) Carbon-free (iii) non-Newtonian slags used to cast (iv) high Al steels (v) Ti-stabilised stainless steels (vi) thin-slabs at high speeds and (vii) round billets. The casting problems encountered with each type of slag are outlined and the characteristics of the developed slags described. The empirical rules developed for conventional casting apply to these specialised continuous casting covered here. So values of the viscosity, break temperature and fraction crystalline phase are determined by the mould dimensions, casting conditions and steel grade. Consequently, much of these data were produced in "New powder versus Conventional powder" and tend to have similar property values. However, some systematic studies have been carried out but there are no published values of the density, surface tension and thermal conductivity.The use of non-Newtonian slags provides a new method of improving steel cleanliness and many of the casting problems encountered in the casting of high Al steels have been reduced using calcium aluminate -based slags; however, some further developments are still needed in both cases.

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“…Al 3 + ions) present. CaF 2 does not alter the concentrations of the various Q n units in the slag 32) i.e. it tends to act as diluent 32) and thus is ignored in the calculation of Q in Eqs.…”

Section: Effects Of Caf 2 and Tio 2 On Structurementioning

confidence: 99%

“…respectively) and is a measure of the de-polymerisation (iii) the parameter, Q, a measure of polymerisation calculated from (NBO/T) (Eq. (8) 31,32) (vi) the concentrations of the various Q n species derived from spectroscopic measurements on the slag, 33) and (vii) the viscosity of the slag.…”

Section: Parameters Used As a Measure Of Polymerisationmentioning

confidence: 99%

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 1 Conventional Mould Powders

Mills

2016

ISIJ International

116

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The physical properties of mould slags are key to their performance in the continuous casting process. The magnitudes of key properties (viscosity, break temperature, f cryst and optical properties) are determined by the mould dimensions, casting conditions and the steel grade being cast. However, a range of other properties (e.g. interfacial tension, density) are needed to minimise defects and process problems. The extant data for thermo-physical properties of conventional mould slags are reviewed here and those for specialist powders (e.g. F-free or for casting TRIP steels) are reviewed in Part 2. It was concluded that there is a need for (i) resolution of the huge differences in thermal conductivity of mould slags for T > 1 050 K obtained with the LP and THW methods (ii) more data for some properties (e.g. C p and density) and more accuracy for others (viscosity, surface tension) (iii) standardised procedures for the determination of f cryst and (iv) characterisation of the porosity in slag films. It was also concluded that (i) gaseous convection makes a significant contribution to the heat transfer in the powder bed and (ii) glassy slag films are probably optically-thin.

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Influence of CaF₂on viscosity of aluminosilicate melts

Cited by 33 publications

References 35 publications

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 2 Specialist Mould Powders

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 1 Conventional Mould Powders

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Influence of CaF2on viscosity of aluminosilicate melts

Cited by 33 publications

References 35 publications

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 2 Specialist Mould Powders

Structure and Properties of Slags Used in the Continuous Casting of Steel: Part 1 Conventional Mould Powders

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Influence of CaF₂on viscosity of aluminosilicate melts