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1.
Equilibrium between CaO-TiO
x
or CaO-TiO
x
-Al2O3 slags and liquid nickel with respect to oxygen and nitrogen has been studied at 1873 K as a function of Ti (or Al) content
in metal, using lime and alumina crucibles. The Al-O, Ti-O, and Ti-Al relations were obtained for liquid nickel equilibrated
with these slags. Nitride capacity,C
(N), defined by (mass pct N) ·
, was evaluated from nitrogen distribution ratios,L
N {= (mass pct N)/[mass pct N], coupled with oxygen content in liquid nickel. Activities of Al2O3 and activity coefficients of TiO2 and TiO1.5 were estimated either from the content of Al, Ti, and O, using the compiled data for the free energy of formation of oxide
and the respective interaction parameters or from the values forL
N andC
(N). 相似文献
2.
By using the data in previous and present slag-metal equilibrium experiments, the activities of SiO2 along the liquidus lines in CaO-SiO2-Al2O3 slags were determined at 1823 and 1873 K from the reaction Si+2O=SiO2 (s), in which the oxygen activities were estimated from the measured oxygen contents or from the combination of nitrogen
distribution ratios (L
N) and nitride capacities (C
N). The activities of Al2O3 were also determined from the reaction 2Al+3O=Al2O3 (s), in which the oxygen activities were estimated from the values for L
N and C
N, or from the reaction 3SiO2 (s)+4Al=2Al2O3 (s)+3Si, in which the activities of SiO2 and the contents of Al and Si along with the respective interaction coefficients were used. The activities of Al2O3 and CaO in the entire liquid region were estimated from the Rein and Chipman’s activities of SiO2 by using the method of Schuhmann. On the basis of these activities, the deoxidation equilibria of Si and Al in steels were
discussed. 相似文献
3.
The Wagner’s first-ordere
o
Ca
and second-order (r
o
Ca
) interaction parameters between Ca and O in liquid nickel were determined as −1220 and 1.35 x 105, respectively, at 1873
K in the equilibrium experiments between liquid nickel and CaO-Al2O3 slags in an A12O3 or CaO crucible. The values fore
Ca
O
, (−3060), r
Ca
o
(8.47 × 105), r
Ca
O,Ca
(6.76 x 105), and r
Ca
O,Ca
(6.76 x 105) were also estimated. Nitride capacities, C(N), defined by (mass pct N)·P
2
3/4
PskN21/2 were obtained by using the present results for nitrogen distribution ratio, LN =(mass pct N)/[mass pct N], and the reported values for the activity of Al2O3. 相似文献
4.
The activities of SiO2 and Al2O3 in CaO-SiO2-Al2O3-MgO slags were determined at 1873 K along the liquidus lines saturated with 2CaO · SiO2, 2(Mg,Ca)O · SiO2, MgO, and MgO · Al2O3 phases using a slag-metal equilibration technique. Based on these and previous results obtained in ternary and quaternary
slags, the isoactivity lines of SiO2 and Al2O3 over the liquid region on the 0, 10, 20, 30, and 40 mass pct Al2O3 planes and those on the 10 and 20 mass pct MgO planes were determined. The activity coefficients of Fe
t
O and MnO, the phase boundary, and the solubility of MgO were also determined. 相似文献
5.
Activity coefficients of MnO and Fe,0 in CaO-SiO2-Al2O3-MnO(<10 mass pct)-Fe,O(<3 mass pct) slags were determined at 1873 K in an Al2O3 or CaO crucible by using the reported values for the activities of Al2O3 and SiO2 or the analyzed contents of oxygen. The activity coefficients of MnO and FetO were found to be constant in the studied concentration range of MnO and FetO. The former increased with an increase in the CaO content, while the latter increased with an increase in the SiO2 content. 相似文献
6.
Koichi Iuchi Kazuki Morita Nobuo Sano 《Metallurgical and Materials Transactions B》1998,29(6):1235-1240
The rate of nitrogen dissolution in CaO-Al2O3-SiO2 and CaO-Al2O3-TiO
x
melts was measured by 14N–15N isotope exchange reaction. The rate constant for the CaO-Al2O3-SiO2 melts at the ratio of mass pct CaO/mass pct Al2O3 = 1 increases as SiO2 content increases, whereas the rate constant for the same melts at the ratio of mass pct CaO/mass pct SiO2 = 1 increases as Al2O3 content increases. The rate constant for the CaO-Al2O3-TiO
x
melts at the ratio of mass pct CaO/mass pct Al2O3 = 1 decreases as the TiO
x
content increases. The activation energies of nitrogen dissolution in CaO-Al2O3-SiO2 melts are about 1.5 to 3 times larger than that of molten pure iron. Moreover, the rate constant of nitrogen dissolution
is independent of the ratio of Ti3+/Ti4+. 相似文献
7.
The activity coefficients of FetO in CaO-Al2O3 and CaO-Al2O3-SiO2 slags with 0.01 to 5 mass pct FetO were determined at 1873 K from the data obtained in the present and previous slag-metal experiments, using an alumina or
lime crucible. It was found that the activity coefficients of FetO obeyed a dilute solution law and increased with increasing the content of SiO2. Based on the findings pertaining to the activity coefficient, the values for the activities of SiO2 and Al2O3 in CaO-Al2O3-SiO2 slags were assessed. 相似文献
8.
Hiroki Hasegawa Yasuhiro Hoshino Takeshi Kasamoto Yuuki Akaida Takaya Kowatari Yasuhiro Shiroki Hiroyuki Shibata Hiromichi Ohta Yoshio Waseda 《Metallurgical and Materials Transactions B》2012,43(6):1405-1412
The thermal conductivities of some synthetic slags containing Al2O3, CaO, and SiO2 have been determined in the temperature range between 1623?K (1350?°C) and 1823?K (1550?°C) by applying a front-heating front-detection laser-flash method. In this method, the temperature response curve is measured in the short initial time period immediately after irradiating a laser pulse. The resultant values obtained by this method are unaffected by the radiative heat transfer. The temperature dependence of the thermal conductivity values were found not to be significant for all slag samples currently investigated. The thermal conductivity (??) of samples is represented with standard deviation less than 2?pct of its value as a function of compositions as follows: $$ \lambda = - 0.48\left[ {{\text{Al}}_{ 2} {\text{O}}_{ 3} } \right] - 0.57\left[ {\text{CaO}} \right] - 0.55\left[ {{\text{SiO}}_{2} } \right] + 57.1{\text{ W m}}^{ - 1} {\text{ K}}^{ - 1} $$ where [Al2O3], [CaO], and [SiO2] are molar percent of Al2O3, CaO and SiO2, respectively. The equation is suggested to cover the region of the following compositions: 8.0?mol pct < Al2O3 <21.0?mol pct, 31.5?mol pct < CaO <41.5?mol pct and 43.0?mol pct < SiO2 <58.1?mol pct. The addition of Al2O3 to slags with a constant CaO/SiO2 molar ratio resulted in an increase in thermal conductivity. In contrast, the effects of addition of SiO2 and CaO are found to be insignificant. 相似文献
9.
Hyuk Kim Hiroyuki Matsuura Fumitaka Tsukihashi Wanlin Wang Dong Joon Min Il Sohn 《Metallurgical and Materials Transactions B》2013,44(1):5-12
The effect of Al2O3 and CaO/SiO2 on the viscosity of the CaO-SiO2-10 mass pct MgO-Al2O3 slags was studied at fully liquid temperatures of 1773 K (1500 °C) and below. At fixed CaO/SiO2 between 0.8 and 1.3, higher Al2O3 content increased the slag viscosity due to the polymerization of the aluminate structures. At fixed Al2O3 of 15 and 20 mass pct, increasing the CaO/SiO2 from 0.8 to 1.3 resulted in lower viscosity due to the depolymerization of the aluminate structure. 相似文献
10.
Min-Su Kim Su-Wan Lee Jung-Wook Cho Min-Seok Park Hae-Geon Lee Youn-Bae Kang 《Metallurgical and Materials Transactions B》2013,44(2):299-308
In order to elucidate the reaction mechanism between high Mn-high Al steel such as twin-induced plasticity steel and molten mold flux composed mainly of CaO-SiO2 during continuous casting process, a series of laboratory-scale experiments were carried out in the present study. Molten steel and molten flux were brought to react in a refractory crucible in a temperature range between 1713 K to 1823 K (1440 °C to 1550 °C) and composition evolution in the steel and the flux was analyzed using inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, and electron probe microanalysis. The amount of SiO2 in the flux was significantly reduced by Al in the steel; thus, Al2O3 was accumulated in the flux as a result of a chemical reaction, 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3). In order to find a major factor which governs the reaction, a number of factors ((pct CaO/pct SiO2), (pct Al2O3), [pct Al], [pct Si], and temperature) were varied in the experiments. It was found that the above chemical reaction was mostly governed by [pct Al] in the molten steel. Temperature had a mild effect on the reaction. On the other hand, (pct CaO/pct SiO2), (pct Al2O3), and [pct Si] did not show any noticeable effect on the reaction. Apart from the above reaction, the following reactions are also thought to happen simultaneously: 2[Mn] + (SiO2) = [Si] + 2(MnO) and 2[Fe] + (SiO2) = [Si] + 2(FeO). These oxide components were subsequently reduced by Al in the molten steel. Na2O in the molten flux was gradually decreased and the decrease was accelerated by increasing [pct Al] and temperature. Possible reactions affecting the Al2O3 accumulation are summarized. 相似文献
11.
Joo Hyun Park Dong Joon Min Hyo Seok Song 《Metallurgical and Materials Transactions B》2004,35(2):269-275
The viscosity of CaO-SiO2 (-MgO)-Al2O3 slags was measured to clarify the effects of Al2O3 and MgO on the structure and viscous flow of molten slags at high temperatures. Furthermore, the infrared spectra of the
quenched slags were analyzed to understand the structural role of Al2O3 in the polymerization or depolymerization of silicate network. The Al2O3 behaves as an amphoteric oxide with the composition of slags; that is, the alumina behaves as a network former up to about
10 mass pct Al2O3, while it acts as a network modifier, in parts, in the composition greater than 10 mass pct Al2O3. This amphoteric role of Al2O3 in the viscous flow of molten slags at the Newtonian flow region was diminished by the coexistence of MgO. The effect of
Al2O3 on the viscosity increase can be understood based on an increase in the degree of polymerization (DOP) by the incorporation
of the [AlO4]-tetrahedra into the [SiO4]-tetrahedral units, and this was confirmed by the infrared (IR) spectra of the quenched slags. The influence of alumina on
the viscosity decrease can be explained on the basis of a decrease in the DOP by the increase in the relative fraction of
the [AlO6]-octahedral units. The relative intensity of the IR bands for the [SiO4]-tetrahedra with low NBO/Si decreased, while that of the IR bands for [SiO4]-tetrahedra with high NBO/Si increased with increasing Al2O3 content greater than the critical point, i.e., about 10 mass pct in the present systems. The variations of the activity coefficient of slag components with composition
indirectly supported those of viscosity and structure of the aluminosilicate melts. 相似文献
12.
Carbon distribution ratios between CaO-Al2O3 slags and Fe-0.0003 to 0.8 mass pct Al-0.2 to 5.6 mass pct C alloys were measured at 1873 K in an Al2O3, CaO, or graphite crucible. The carbon distribution ratios were dependent on the oxygen potential, determined by theAl/(Al2O3) equilibrium, not by theC/CO (P co = 1 atm) equilibrium. The (mass pct C)/a c ratios were proportional to the activity of Al in logarithmic form with a slope of 2/3, indicating that carbon in slag is dissolved as C2? ion. Solubilities of carbon in CaO-Al2O3 slags were also measured at 1873 K under the CO-CO2-Ar gas mixtures in an Al2O3 or graphite crucible. It was found that C2? ion is present in the range of log $P_{O_2 } $ (atm) < ?15 and CO 3 2? ion in the range of log $P_{O_2 } $ (atm) > ?7. 相似文献
13.
The sulphide capacities (CS) of CaO–SiO2–Al2O3–MgO–TiO2 blast furnace slags were experimentally measured at 1773?K, and the percentages of free oxygen ions (O2?) and bridge oxygen (O0) of molten slag were calculated using molecular dynamics at 1773?K. The measured and calculated results were closely correlated with the change in CaO/SiO2, MgO, and Al2O3 contents in the slag. The results show that CS increases with increasing CaO/SiO2 and MgO contents in the slag, but decreases with increasing Al2O3 content. The effects of O2? and O0 on CS were analysed using multiple linear regression, and results show that sulphide increases with the increase in the mass percentage of free oxygen and decreases with the increase in the mass percentage of bridge oxygen. 相似文献
14.
Silicon-oxygen equilibria in an Fe-0.003 ~ 27 mass pct Si alloy in equilibrium with the CaO-SiO2 slags were studied in the temperature range of 1823 to 1923 K using a lime crucible. At the same time, nitrogen distribution
ratios, LN, between slag and metal were measured, and from these results and the reported values for activities of SiO2, nitride capacities,
, defined by (mass pct N).
were evaluated. It was found that the values for LN decreased, whereas those for
increased with an increase in temperature. Activities of SiO2 were determined using the values for LN and
obtained in previous gas-slag experiments. These values were compared with the previous results. 相似文献
15.
The effect of Na2O on the equilibrium phosphorous distribution ratio between slag and iron or iron alloys, LP, has been measured for CaO-SiO2, CaO-FeOr-SiO2 (CaO or 2CaO·SiO2 saturated), and CaO-Al2-SiO2 slags. The addition of Na2O to CaO-SiO2 slags significantly increases LP and the phosphate capacity. A 25 pct CaO-25 pct Na2O-SiO2 slag has a distribution ratio nearly two orders of magnitude greater than a comparable binary 50 pct CaO-SiO2 slag. For the CaO-saturated slags containing 40 wt pct FeOT, the addition of 6 wt pct Na2O increases LP by a factor of 5. For the 2CaO·SiO2-saturated CaO-FeOT-SiO2 slag, there is an optimum FeOr content (20 wt pct) for dephosphorization, and 10 wt pct Na2O increases LP by a factor of 2. For reducing slags typically used in ladle metallurgy for Al-killed steels (50 pct CaO-40 pct Al2O3-10 pct SiO2), as little as 3 wt pct Na2O increases LP by a factor of 100. The present results indicate that small additions of Na2O to conventional steelmaking slags can greatly improve dephosphorization.
Formerly Graduate Student, Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University. 相似文献
16.
Noritaka Saito Naoto Hori Kunihiko Nakashima Katsumi Mori 《Metallurgical and Materials Transactions B》2003,34(5):509-516
The effect of MgO, TiO2, or Fe2O3 on the viscosity of 40CaO-40SiO2-20Al2O3 (mass pct) slags has been measured by the rotating crucible viscometer. Viscosity of these quaternary slags decreased with
an increase in the content of additive oxide. At the same content of additive oxide, the viscosity decreases from MgO, TiO2 to Fe2O3. In addition, the effect of SiO2 or Al2O3 on the viscosity of 26.1CaO-73.9Fe2O3 (mass pct) (CF) and 14.9CaO-85.1Fe2O3 (mass pct) (CF2) slags has been measured. Viscosity of calcium ferrite slags increased with increasing SiO2 or Al2O3 content. Al2O3 was found to be more effective for increasing the viscosity at the same content of the additive oxide.
This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties
& Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002. 相似文献
17.
The rate of nitrogen dissolution in CaO-Al2O3, CaO-SiO2, and CaO-CaF2 melts was measured by 14N-15N isotope exchange reaction. The rate constant of nitrogen dissolution in CaO-based oxide melts, which is defined as first
order with respect to nitrogen partial pressure, was found to be much smaller than that in molten iron-based alloys investigated
in our previous work. The activation energies for nitrogen dissolution in 40 mass pct CaO-60 Al2O3 and 50 CaO-50 SiO2 melts are 224 and 581 kJ/mol, respectively. For CaO-Al2O3 and CaO-SiO2, dependence of the rate constant on composition is very similar to that of nitride capacities. Moreover, it was confirmed
that the rate constant was not affected by oxygen or nitrogen partial pressure. 相似文献
18.
Trinath Talapaneni Natraj Yedla Snehanshu Pal Smarajit Sarkar 《Metallurgical and Materials Transactions B》2017,48(3):1450-1462
Blast furnaces are encountering high Alumina (Al2O3 > 25 pct) in the final slag due to the charging of low-grade ores. To study the viscosity behavior of such high alumina slags, synthetic slags are prepared in the laboratory scale by maintaining a chemical composition of Al2O3 (25 to 30 wt pct) CaO/SiO2 ratio (0.8 to 1.6) and MgO (8 to 16 wt pct). A chemical thermodynamic software FactSage 7.0 is used to predict liquidus temperature and viscosity of the above slags. Experimental viscosity measurements are performed above the liquidus temperature in the range of 1748 K to 1848 K (1475 °C to 1575 °C). The viscosity values obtained from FactSage closely fit with the experimental values. The viscosity and the slag structure properties are intent by Fourier Transform Infrared (FTIR) and Raman spectroscopy. It is observed that increase in CaO/SiO2 ratio and MgO content in the slag depolymerizes the silicate structure. This leads to decrease in viscosity and activation energy (167 to 149 kJ/mol) of the slag. Also, an addition of Al2O3 content increases the viscosity of slag by polymerization of alumino-silicate structure and activation energy from 154 to 161 kJ/mol. It is witnessed that the activation energy values obtained from experiment closely fit with the Shankar model based on Arrhenius equation. 相似文献
19.
The crystallization behavior of a calcium-aluminate system with various MgO content from 2.5 to 7.5?wt pct and CaO/Al2O3 ratios between 0.8 and 1.2 has been examined using a confocal laser scanning microscope (CLSM). CCT (continuous cooling transformation) and time temperature transformation (TTT) diagrams were constructed to identify the primary crystal phase of slag at different compositions and at cooling rates between 25 and 800?K/minutes. In the slag at a CaO/Al2O3 ratio of 1.0, crystallization temperature increased during isothermal and continuous cooling with higher MgO content, and the shortest incubation time was observed at 5?wt pct MgO. When MgO content was fixed to be 5?wt pct, crystallization temperature increased with lower CaO/Al2O3 ratio. According to the slag composition, cooling rates and temperature, the primary phase could be CA, or C5A3, or C3A, or C3MA2, or MgO, and the crystal morphology changes from dendrites to faceted crystals to columnar crystals in this composition range. 相似文献
20.
Measurements have been made of the ratio of ferric to ferrous iron in CaO-Al2O3-SiO2 and MgO-CaO-Al2O3-SiO2 slags at oxygen activities ranging from equilibrium with pCO2/pCO≈0.01 to as high as air at temperatures of 1573 to 1773 K. At 1773 K, values are given by $\begin{gathered} \log {\text{ }}\left( {\frac{{Fe^{3 + } }}{{Fe^{2 + } }}} \right) = 0.3( \pm {\text{ }}0.02){\text{ }}Y + {\text{ }}0.45( \pm {\text{ }}0.01){\text{ }}\log \hfill \\ \left( {\frac{{pCO_2 }}{{pCO}}} \right) - 1.24( \pm {\text{ }}0.01) \hfill \\ \end{gathered} $ where Y=(CaO+MgO)/SiO2, for melts with the molar ratio of CaO/SiO2=0.45 to 1.52, 10 to 15 mol pct Al2O3, up to 12 mol pct MgO (at CaO/SiO2≈1.5), and with 3 to 10 wt pct total Fe. Available evidence suggests that, to a good approximation, these redox equilibria are independent of temperature when expressed with respect to pCO2/pCO, probably from about 1573 to 1873 K. Limited studies have also been carried out on melts containing about 40 mol pct Al2O3, up to 12 mol pct MgO (at CaO/SiO2≈1.5), and 3.6 to 4.7 wt pct Fe. These show a strongly nonideal behavior for the iron redox equilibrium, with $\frac{{Fe^{3 + } }}{{Fe^{2 + } }} \propto \left( {\frac{{pCO_2 }}{{pCO}}} \right)^{0.37} $ The nonideal behavior and the effects of basicity and Al2O3 concentration on the redox equilibria are discussed in terms of the charge balance model of alumino-silicates and the published structural information from Mössbauer and NMR (Nuclear Magnetic Resonance) spectroscopy of quenched melts. 相似文献