Study on Structure Characteristics of B2O3 and TiO2-bearing F-Free Mold Flux by Raman Spectroscopy

2013 ◽  
Vol 32 (3) ◽  
pp. 265-273 ◽  
Author(s):  
Zhen Wang ◽  
Qifeng Shu ◽  
Kuochih Chou
Keyword(s):  
Raman Spectroscopy ◽  
Mold Flux ◽  
Complex Structure ◽  
Slag System ◽  
Degree Of Polymerization ◽  
Structural Group ◽  
Destructive Effect ◽  
Structure Characteristics ◽  
Structure Unit ◽  
Sheet Structure

AbstractStructure characteristics of fluoride-Free mold flux containing simultaneously B2O3 and TiO2 have been investigated by Raman spectroscopy in this work. Raman spectra for glass samples with different basicities, different contents of TiO2 and B2O3 were recorded during the experiments. According to the experiments results, increase of TiO2 content leads to the appearance of [TiO4] and [TiO6] structure groups, and [TiO4] becomes the main structure unit in the system. TiO2 produces a certain destructive effect on Si-O-Si network structure as well as large borate group and conducive to the formation of some other complex structure groups, such as (Si,Ti) coupling in sheet unit. It can be concluded that, with the increase of B2O3, the ratio of mixing of the Q0 structure unit and [TiO4] structural group decrease and the ratio of sheet structure unit increase, and there forms large borate group. Existence of B2O3 increases polymerization degree of the slag system. In addition, increasing basicity causes to the decrease of Q2 and sheet structure unit and increase of mixing of the Q0 structure unit and [TiO4] structural group, and weakening the large borate group. It could be concluded that the increase of basicity reduces the degree of polymerization of the system.

scholarly journals Effects of Li2O on Structure and Viscosity of CaO-Al2O3-Based Mold Fluxes

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Lifeng Chen ◽  
Kun Liu ◽  
Peng Han ◽  
Bin Yang ◽  
Lianghua Feng
Keyword(s):  
Molecular Dynamics ◽  
Mold Flux ◽  
Molten Slag ◽  
Complex Structure ◽  
Degree Of Polymerization ◽  
Dynamics Simulation ◽  
Systematic Analysis ◽  
Structure Characteristics ◽  
Mold Fluxes ◽  
Stable Structures

Since CaO-Al2O3-based mold fluxes are one of the most important mold flux systems in metallurgic processes, it is important to explore their structure characteristics and viscosity. Molecular dynamics simulation is performed to study the effect of w(CaO)/w(Al2O3) ratio on both the structural and viscosity properties of CaO-Al2O3-based mold fluxes. A systematic analysis of the structure and thermodynamics on CaO-Al2O3-based mold fluxes is carried out, and it is well known that the viscosity of mold fluxes is related to the structure. The results show that the formation of stable structures of Si-O in the mold fluxes was beneficial to reduce the probability of structural interconnection, degree of polymerization, and viscosity of the molten slag. In the cationic structure, the contents of Ca-O-Al and Ca-O-Si are more stable, the interconnection of the Ca-O-Al and Ca-O-Si network weakens, and the viscosity decreases. The tetrahedra [AlO4] and [SiO4] have similar structures, but they exhibit different thermodynamic and physical properties. Viscosity test shows that CaO/Al2O3 = 0.88–2 continuously increased, when the cosolvent content Li2O = 1%–4%, CaO-Al2O3-based mold flux viscosity decreased, the degree of network structure polymerization decreased, and the complex structure depolymerized. Increasing the water content in the cosolvent is beneficial to reduce the viscosity of the crystallizer.

Investigation the influences of B2O3and R2O on the structure and crystallization behaviors of CaO–Al2O3based F-free mold flux

2018 ◽  
Vol 115 (3) ◽  
pp. 304 ◽  
Author(s):  
Jiangling Li ◽  
Bowen Kong ◽  
Xiangyu Gao ◽  
Qingcai Liu ◽  
Qifeng Shu ◽  
...  
Keyword(s):  
Liquidus Temperature ◽  
Mold Flux ◽  
Crystallization Process ◽  
Degree Of Polymerization ◽  
Scanning Calorimetry ◽  
Structural Investigations ◽  
Crystallization Ability ◽  
Mold Fluxes ◽  
New Type ◽  
Positive Effect

The influences of B2O3and R2O on the structure and crystallization of CaO–Al2O3based F-free mold flux were investigated by Raman Spectroscopy and Differential Scanning Calorimetry Technique, respectively, for developing a new type of F-free mold flux. The results of structural investigations showed that B3+is mainly in the form of [BO3]. And [BO3] appears to form BIII–O–Al linkage which will produce a positive effect on forming [AlO4] network. The number of bridging oxygen and the degree of polymerization of [AlO4] network structure for CaO–Al2O3system were also increased with the increasing of B2O3. On the contrary, with the addition of R2O into CaO–Al2O3–B2O3system, the number of bridging oxygen and the degree of polymerization of [AlO4] network were decreased. DSC results showed that the crystallization process became more sluggish with the increase of B2O3, which indicated that the crystallization ability was weakened. While the quenched mold fluxes crystallized more rapidly when introducing R2O. In other word, the crystallization rates of CaO–Al2O3based slags were accelerated by the introduction of R2O. The liquidus temperature and crystallization temperature were decreased with the increasing amount of B2O3or by addition of R2O into CaO–Al2O3system. Only one kind of crystal was precipitated in 8% B2O3and %R2O-containing samples, which was CaAl2O4identified by SEM-EDS. When the content of B2O3increased from 8% to 16%, Ca3B2O6is clearly observed, demonstrating that the crystallization ability of Ca3B2O6is enhanced by the increasing concentration of B2O3in mold flux. The Ca/Al ratio of the generated calcium aluminate has been altered from 1:2 to 1:4 with the increasing of B2O3. The size of CaAl2O4crystal is gradually increased with the addition of R2O. The crystallization ability of CaAl2O4is promoted by R2O.

scholarly journals Viscosity and Structure of a CaO-SiO2-FeO-MgO System during a Modified Process from Nickel Slag by CaO

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2562 ◽  
Author(s):  
Yingying Shen ◽  
Junkai Chong ◽  
Ziniu Huang ◽  
Jianke Tian ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Solid Phase ◽  
Molar Fraction ◽  
Slag System ◽  
Softening Temperature ◽  
Degree Of Polymerization ◽  
Primary Phase ◽  
Basic Oxide ◽  
High Iron Content ◽  
Critical Viscosity

There is a high iron content in nickel slag that mainly exists in the fayalite phase. Basic oxide can destroy the stable structure of fayalite which is beneficial to the treatment and comprehensive utilization of nickel slag. The research was based on the composition of the raw nickel slag, taking the CaO-SiO2-FeO-MgO system as the object and CaO as a modifier. The effect of basicity on the melting characteristics, viscosity and structure of the CaO-SiO2-FeO-MgO system was studied. The relationship between the viscosity and structure of the CaO-SiO2-FeO-MgO system was also explored. The results show as follows: (1) When the basicity is lower than 0.90, the primary phase of the slag system is olivine phase. When the basicity is greater than 0.90, the primary phase of the slag system transforms into monoxide. When the basicity is 0.90, olivine and monoxide precipitate together as the temperature continues to decrease. At the same time, the liquidus temperature, softening temperature, hemispherical temperature, and flow temperature all reach the lowest value. (2) With the increase of basicity, the critical viscosity temperature of the CaO-SiO2-FeO-MgO system decreases first and then increases. Critical viscosity temperature is the lowest at the basicity of 0.90, which is 1295 °C. (3) When the slag system is heterogeneous, the viscosity of the molten slag increases rapidly because of the quantity of solid phase precipitated from the CaO-SiO2-FeO-MgO system. (4) When the slag system is in a homogeneous liquid phase, the molar fraction of O0 decreases with the increase of basicity and the mole fraction of O−, and O2− increases continuously at the basicity of 0.38~1.50. The silicate network structure is gradually depolymerized into simple monomers, resulting in the degree of polymerization, and the viscosity, being reduced. The mole fraction of different kinds of oxygen atoms is converged to a constant value when the basicity is above 1.20.

Structural Properties of Molten CaO–SiO2–P2O5–FeO System

2017 ◽  
Vol 36 (9) ◽  
pp. 871-876
Author(s):  
Jiang Diao ◽  
Zhaoqun Ke ◽  
Lu Jiang ◽  
Zhen Zhang ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Molecular Dynamic ◽  
Structural Properties ◽  
Spectroscopic Analysis ◽  
Potential Model ◽  
Slag System ◽  
Md Simulations ◽  
Degree Of Polymerization ◽  
Slag Basicity ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Analysis

AbstractThe structural properties of molten CaO–SiO2–P2O5–FeO slag system with varying slag basicity have been investigated by molecular dynamic (MD) simulations using the pairwise potential model. The result shows that more than 95 % Si and 98 % P are four coordinated and form tetrahedral structures. Non-bridging oxygen occupies a predominant position in the system. With basicity increasing from 0.6 to 1.5, the proportion of non-bridging oxygen increases from 66.3 % to 77.3 %, whilst the bridging oxygen decreases from 30.1 % to 10.2 %. Both the result of MD simulations and Raman spectroscopic analysis show the proportion of Q0 increases with increasing slag basicity, whilst Q2 and Q3 decrease. The degree of polymerization of CaO–SiO2–P2O5–FeO system decreases with increasing slag basicity.

scholarly journals LEFT-INVARIANT ALMOST PARA-COMPLEX EINSTEINIAN STRUCTURES ON SIX-DIMENSIONAL NILPOTENT LIE GROUPS

2017 ◽  
pp. 88-95
Author(s):  
Nikolay Smolentsev ◽  
Nikolay Smolentsev
Keyword(s):  
Lie Groups ◽  
Complex Structure ◽  
New Left ◽  
Riemannian Metrics ◽  
Nilpotent Lie Groups ◽  
Complex Structures ◽  
Structural Group ◽  
Almost Complex ◽  
Flat Structures ◽  
Simply Connected

As is well known, there are 34 classes of isomorphic simply connected six-dimensional nilpotent Lie groups. Of these, only 26 classes admit left-invariant symplectic structures and only 18 admit left-invariant complex structures. There are five six-dimensional nilpotent Lie groups G , which do not admit neither symplectic, nor complex structures and, therefore, can be neither almost pseudo- Kӓhlerian, nor almost Hermitian. In this work, these Lie groups are being studied. The aim of the paper is to define new left-invariant geometric structures on the Lie groups under consideration that compensate, in some sense, the absence of symplectic and complex structures. Weakening the closedness requirement of left-invariant 2-forms ω on the Lie groups, non-degenerated 2-forms ω are obtained, whose exterior differential dω is also non-degenerated in Hitchin sense [6]. Therefore, the Hitchin’s operator K dω is defined for the 3-form dω . It is shown that K dω defines an almost complex or almost para-complex structure for G and the couple ( ω, dω ) defines pseudo-Riemannian metrics of signature (2,4) or (3,3), which is Einsteinian for 4 out of 5 considered Lie groups. It gives new examples of multiparametric families of Einstein metrics of signature (3,3) and almost para-complex structures on six-dimensional nilmanifolds, whose structural group is being reduced to SL (3 , R) SO (3 , 3). On each of the Lie groups under consideration, compatible pairs of left-invariant forms (ω, Ω), where Ω = d ω, are obtained. For them the defining properties of half-flat structures are naturally fulfilled: d Ω = 0 and ωΩ = 0. Therefore, the obtained structures are not only almost Einsteinian para-complex, but also pseudo- Riemannian half-flat.

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

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 871
Author(s):  
Xingjuan Wang ◽  
Hebin Jin ◽  
Liguang Zhu ◽  
Ying Xu ◽  
Ran Liu ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Mold Flux ◽  
Network Formation ◽  
Degree Of Polymerization ◽  
Slag Viscosity ◽  
Continuous Casting Mold ◽  
Flow Activation Energy ◽  
Casting Mold ◽  
Fluorine Ions ◽  
Caf2 Content

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.

scholarly journals Role of B2O3 on structure and shear-thinning property in CaO–SiO2–Na2O-based mold fluxes

2019 ◽  
Vol 38 (2019) ◽  
pp. 750-759
Author(s):  
Li-Guang Zhu ◽  
Zhi-Peng Yuan ◽  
Ying Xu ◽  
Kai-Xuan Zhang ◽  
Yi-Hua Han
Keyword(s):  
Continuous Casting ◽  
Newtonian Fluid ◽  
High Speed ◽  
Structural Changes ◽  
Mold Flux ◽  
Shear Thinning ◽  
Degree Of Polymerization ◽  
Dynamics Simulation ◽  
Shear Rates ◽  
Mold Fluxes

AbstractMost traditional mold fluxes are Newtonian fluids, and their constant viscosity has certain limitations in continuous casting. A new non-Newtonian fluid mold flux with shear-thinning behavior, i.e., a mold flux with a relatively high viscosity at lower shear rates and a relatively low viscosity at higher shear rates, is required to satisfy the mold-flux performance requirements for high-speed continuous casting. The addition of a certain amount of B2O3 to a CaO–SiO2–Na2O-based mold flux can result in a shear-thinning property. To obtain an improved understanding of the mechanism of this characteristic, a molecular-dynamics simulation method was used to study the microstructural changes of the mold flux. Structural changes of mold-flux samples were analyzed and verified by Raman spectroscopy. The results of the two methods were almost the same, both resulted from the addition of B2O3 and changed the microstructure and degree of polymerization of the mold flux, which resulted in the shear-thinning property of the mold flux. This non-Newtonian fluid mold flux was used in square-billet casting tests, and the quality of the slab was improved effectively.

Influence of Nb2O5 and basicity on the viscosity and structure of CaO-SiO2-Nb2O5-CeO2-CaF2 slag system

2020 ◽  
Vol 117 (3) ◽  
pp. 307
Author(s):  
Zhuang Ma ◽  
Zengwu Zhao ◽  
Wentao Guo ◽  
Zhi Wang
Keyword(s):  
Activation Energy ◽  
Slag System ◽  
Rotating Cylinder ◽  
Degree Of Polymerization ◽  
X Ray Diffraction ◽  
Structural Units ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Bayan Obo ◽  
Cylinder Method

In order to utilize niobium concentrate of Bayan Obo effectively, the effect of Nb2O5 and basicity on the viscosity of CaO-SiO2-Nb2O5-5.0 wt.% CeO2-5.0 wt.% CaF2 slag system was studied from 1653 to 1813 K in reducing atmosphere by rotating cylinder method. For the same condition, the as-quenched samples were investigated through X-ray diffraction and Raman spectroscopy. The results show that the viscosity, break temperature and activation energy of viscous flow decrease with the increase of Nb2O5 and basicity. Raman spectra show that the Nb4+ ions exist in the form of [NbO6] octahedron with different distortion and little [NbO4] tetrahedron in the slags. The Nb2O5 addition and basicity lower the degree of polymerization, where the complex Si-O network is depolymerized into simple structural units.

scholarly journals Exploitation of Mold Flux for the Ti-bearing Welding Wire Steel ER80-G

2019 ◽  
Vol 38 (2019) ◽  
pp. 873-883 ◽  
Author(s):  
Zhanlong Piao ◽  
Liguang Zhu ◽  
Xingjuan Wang ◽  
Zengxun Liu ◽  
Hebin Jin ◽  
...  
Keyword(s):  
Mold Flux ◽  
Surface Defects ◽  
Slag System ◽  
Melting Rate ◽  
Welding Wire ◽  
Crystalline Fraction ◽  
Peritectic Steel ◽  
Flux System ◽  
Wire Steel ◽  
O 10

AbstractIn order to improve the surface defects of strand, the mold flux is exploited for the Ti-bearing welding wire steel ER80-G. The composition of mold flux is designed by analyzing the solidification characteristics of ER80-G and the slag system isothermal section diagram, simulating by the FactSage thermodynamics software. The Ti-bearing welding wire steel ER80-G belongs to the peritectic steel. The melting point range of the newly designed mold flux system is from 1030∘C to 1129∘C, the melting rate range is from 58 s to 64 s, the viscosity range at the temperature of 1300∘C is from 0.33 Pa·s to 0.50 Pa·s, the crystallization temperature range is from 1160∘C to 1293∘C, the crystalline fraction range is from 34% to 85%. The surface defects of strand which transverse depression, longitudinal depression, slag runner and so on were obviously improved when the newly design mold flux F3, F5, F9 were used to the production respectively. Those results suggest that 0.9 basicity with 28.4%-CaO, 31.6%-SiO2,3%-MgO, 10%-Na2O, 10%-CaF2, 6%-Al2O3, 1%-Fe2O3, 10%-Tc and all groups with 1.0 and 1.1 basicity show the best properties for Ti-bearing welding wire steel ER80-G.

Structural aspects of the hydrolysis products of metal alkoxides and metal trialkylsilyloxides

1969 ◽  
Vol 47 (22) ◽  
pp. 4101-4111 ◽  
Author(s):  
J. W. Lorimer ◽  
D. E. G. Jones
Keyword(s):  
Metal Oxide ◽  
Complex Structure ◽  
Theoretical Models ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Degree Of Hydrolysis ◽  
Special Cases ◽  
Plausible Mechanism ◽  
Branched Chains ◽  
Structural Aspects

The average degree of polymerization [Formula: see text] depends on the average degree of hydrolysis [Formula: see text] as[Formula: see text] over a large range of [Formula: see text] for all metal oxide alkoxides and oxide trialkylsilyloxides that have been formed by hydrolysis and examined in solution. A number of general theoretical models are developed which permit quantitative interpretation of the parameters a and b. Mixtures of linear or branched chains in proportions governed wholly or partly by the degree of polymerization of the unhydrolyzed alkoxide can explain all the data on oxide alkoxides in solution in their corresponding alcohol, and the model leads to a plausible mechanism for disproportionation. Similar models with more complex structure can be involved in the metal oxide trialkylsilyloxides. Heterogeneity in the composition of the repeating units or in the number of metal–oxygen–metal bridges between successive repeating units can also be significant for both oxide alkoxides and oxide trialkylsilyloxides. Models involving cyclic chains are possible, but steric effects make them improbable in many cases. Mixtures of chains with equal average degrees of hydrolysis for each type of chain have been assumed in previous analyses, but are shown to be special cases of the more general model.

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