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1.
Min‐Oh Suk Sung‐Koo Jo Chang‐Woo Seo Seon‐Hyo Kim Jeong‐Sik Kim Sang‐Chul Shim Jeong‐Tae Kim 《国际钢铁研究》2005,76(4):287-295
An equilibrium study was carried out at 1873K to ascertain the effect of carbon in CaO‐SiO2‐Al2O3‐MgO‐MnO‐FetO slag systems on their FetO and MnO activity coefficients, representing the slags’ thermodynamic potential for steel reoxidation. Both γf eto and γm no showed not only a sharp increment but also a simultaneous slow decrement by increasing carbon content in slag, suggesting opposite roles of the carbon according to its stable forms. XPS (X‐ray photoelectron spectroscopy) was introduced to clarify the stable forms of carbon in slag. XPS results prove that carbon dissolves in slag as carbonate, and carbide ions under oxidizing and reducing atmospheres, respectively. It was concluded that carbonate ions increase γf eto and γm no , but that carbide decreases them. This paper suggests an application method of the present results to actual ladle refining processes, in order to enhance steel cleanliness with maintaining (FetO + MnO) in slag to some allowable amount. 相似文献
2.
Chul-Hwan Choi Sung-Koo Jo Seon-Hyo Kim Kwang-Ro Lee Jeong-Tae Kim 《Metallurgical and Materials Transactions B》2004,35(1):115-120
To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated
by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of
CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent
crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system
were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe
t
O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels. 相似文献
3.
Thermodynamic behavior of nickel in CaO-SiO<Subscript>2</Subscript>-Fe<Subscript>t</Subscript>O slag
Sang Hoon Lee Seok Min Moon Dong Joon Min Joo Hyun Park 《Metallurgical and Materials Transactions B》2002,33(1):55-59
The distribution ratio of nickel between Ag-Ni alloy and CaO-SiO2-Fe
t
O slag at high temperatures was measured to clarify the dissolution mechanism of nickel in this melt. Also, the nickel oxide
capacity was suggested and was compared to phosphate and sulfide capacities. The dissolution mechanism of nickel into the
CaO-SiO2-Fe
t
O slags could be described by the following equation from the effect of oxygen potential and slag basicity on nickel dissolution
behavior:
The nickel oxide capacity increases with increasing CaO/SiO2 ratio at a fixed Fe
t
O content. When the ratio of X
CaO to
(C/S) is about 1.1 to 1.3, log
increases with increasing Fe
t
O content up to about 35 mol pct, followed by a nearly constant value of
. In the composition of C/S=0.5 to 0.7, log
exhibits a maximum value at about 50 mol pct Fe
t
O. From the iso-
trends in ternary phase diagram, nickel oxide capacity dominantly depends on Fe
t
O content in slags; it exhibits a maximum value of
at
. The relationship between nickel oxide capacity and phosphate (sulfide) capacities exhibit linear correlations, as expected
from theoretical equations. 相似文献
4.
The thermodynamic equilibria of manganese and phosphorus between liquid iron and CaO‐MgOSat‐SiO2‐FetO‐MnO‐P2O5‐Al2O3 (0–33%) ladle slag have been investigated at 1873 K from the viewpoint of Mn and P yields for the production of high‐strength steels. The equilibrium distribution ratios of Mn and P were found to increase with increasing FetO content; however, these ratios vary with basicity, but they do this the other way round. The addition of alumina into slag at a fixed basicity and FetO content decreases both the equilibrium manganese and phosphorus distributions. The equilibrium distribution ratios were discussed in terms of the variation of activity coefficients of FetO, MnO and PO2.5, according to the slag basicity and Al2O3 content. The quantitative contributions of basicity and (%FetO + %MnO) on LMn and LP were empirically determined and their usefulness was discussed with the aid of plant data: To improve Mn and P yields in the practical RH operation, it is strongly recommended that Fe‐Mn and Fe‐P alloys be added after Al deoxidation treatment inducing relatively high Al2O3 in slag and maintaining low FetO content. In addition, a ladle slag composition for the targeted Mn and P contents in liquid iron was substantially estimated using the empirical relationships. 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.
The slag system of CaO‐SiO2‐Al2O3‐MgO‐Cr2O3‐MnO‐FetO relevant to refining chromium‐containing steels such as bearing steel is thermodynamically assessed at 1873 K. The activity coefficient of FetO shows an initially rapid increment followed by a gradual reduction according to Cr2O3 content at a constant basicity, and decreases with increasing slag basicity. γMnO is decreased abruptly by increasing Cr2O3 content and thereafter, maintains a nearly constant level. From the standpoint of inclusion control, the Cr2O3 presence in ladle refining slags is thermodynamically harmful in that it minimizes the inclusion level by inducing the increment of γFetO even though Cr2O3 exists in extremely small amounts. However, it is beneficial in that it diminishes AI reoxidation by decreasing γMnO. The presence of carbon in slag decreases γFetO and γMnO, which turns out to be favourable for the reduction of Al reoxidation. The thermodynamic equilibria of chromium and manganese are quantified in terms of FetO and Cr2O3 content as well as slag basicity by using multiple regression analysis. LCr and LMn are increased by the presence of Cr2O3, indicating a low recovery efficiency of Cr and Mn in the treatment of ferroalloy addition. In determining LS values, Cr2O3 is not so important as the basicity of slags. 相似文献
7.
During the production of aluminum by carbothermic reduction, large quantities of Al2O and Al vapor are generated. For the process to be economical, the aluminum and energy associated with these species must
be captured and used in the process. This is accomplished by reacting them with carbon to form Al4C3. The mechanism and rate of the reactions of gas containing Al and Al2O with various forms of carbon was studied. The Al2O-Al-CO gas was generated by reacting an Al4C3-Al2O3 melt with carbon at high temperatures (2000 °C to 2050 °C). The gas then reacted with carbon at lower temperatures (1900
°C to 1950 °C). The only form of carbon that reacted extensively, forming Al4C3, was wood charcoal; with other forms of carbon, such as metallurgical coke and petroleum coke, primarily only Al2O3 condensed on the surface formed. The rate of formation of Al4C3 on wood charcoal was found to be controlled by the diffusion of Al2O and Al through the Al4C3 product layer, and their effective diffusivities were estimated to be 0.82 and 1.31 cm2/s, respectively. Over 90 pct of the carbide is formed by Al2O and only 10 pct by Al vapor. When an Al4C3-Al2O3 dense slag was formed on the charcoal at lower temperatures (1920 °C to 1930 °C) and then reacted at a higher temperature,
it appears that the slag and carbon reacted to form Al4C3 relatively fast. The volume of Al4C3 formed is much greater than that of the original carbon. It is believed that this is the reason the other forms of carbon
with lower porosity (25 pct vs 60 pct) did not react significantly. Any amount of Al4C3 formed would quickly fill the pores of the more dense carbon, stopping any further reaction. 相似文献
8.
Ye-Jin Kim Dae-Hee Woo Henri Gaye Hae-Geon Lee Youn-Bae Kang 《Metallurgical and Materials Transactions B》2011,42(3):535-545
The activities of MnO and MnS in a MnO-SiO2-Al2O3(or AlO1.5)-MnS liquid oxysulfide solution were investigated by employing the gas/liquid/Pt-Mn alloy chemical equilibration technique
under a controlled atmosphere at 1773 K (1500 °C). Also, the sulfide capacity, defined as C
S = (wt pct S)(pO2/pS2)1/2, in MnO-SiO2-Al2O3 slag with a dilute MnS concentration was obtained from the measured experimental data. As X
SiO2/(X
MnO + X
SiO2) in liquid oxysulfide increases, the activity coefficient of MnO decreases, while that of MnS first increases and then decreases.
As X(AlO1.5) in liquid oxysulfide increases, the activity coefficient of MnS increases, while no remarkable change is observed for the
activity coefficient of MnO. The behavior of the activity coefficient of MnS was qualitatively analyzed by considering MnO + A
x
S
y
(SiS2 or Al2S3) = MnS + A
x
O
y
(SiO2 or Al2O3) reciprocal exchange reactions in the oxysulfide solution. The behavior was shown to be consistent with phase diagram data,
namely, the MnS saturation boundary. Quantitative analysis of the activity coefficient of the oxysulfide solution was also
carried out by employing the modified quasichemical model in the quadruplet approximation. 相似文献
9.
Xue-Min Yang Jian-Ping Duan Cheng-Bin Shi Meng Zhang Yong-Liang Zhang Jian-Chang Wang 《Metallurgical and Materials Transactions B》2011,42(4):738-770
A thermodynamic model for calculating the phosphorus distribution ratio between top–bottom combined blown converter steelmaking
slags and molten steel has been developed by coupling with a developed thermodynamic model for calculating mass action concentrations
of structural units in the slags, i.e., CaO-SiO2-MgO-FeO-Fe2O3-MnO-Al2O3-P2O5 slags, based on the ion and molecule coexistence theory (IMCT). Not only the total phosphorus distribution ratio but also
the respective phosphorus distribution ratio among four basic oxides as components, i.e., CaO, MgO, FeO, and MnO, in the slags and molten steel can be predicted theoretically by the developed IMCT phosphorus distribution
ratio prediction model after knowing the oxygen activity of molten steel at the slag–metal interface or the Fe
t
O activity in the slags and the related mass action concentrations of structural units or ion couples in the slags. The calculated
mass action concentrations of structural units or ion couples in the slags equilibrated or reacted with molten steel show
that the calculated equilibrium mole numbers or mass action concentrations of structural units or ion couples, rather than
the mass percentage of components, can present the reaction ability of the components in the slags. The predicted total phosphorus
distribution ratio by the developed IMCT model shows a reliable agreement with the measured phosphorus distribution ratio
by using the calculated mass action concentrations of iron oxides as presentation of slag oxidation ability. Meanwhile, the
developed thermodynamic model for calculating the phosphorus distribution ratio can determine quantitatively the respective
dephosphorization contribution ratio of Fe
t
O, CaO + Fe
t
O, MgO + Fe
t
O, and MnO + Fe
t
O in the slags. A significant difference of dephosphorization ability among Fe
t
O, CaO + Fe
t
O, MgO + Fe
t
O, and MnO + Fe
t
O has been found as approximately 0.0 pct, 99.996 pct, 0.0 pct, and 0.0 pct during a combined blown converter steelmaking
process, respectively. There is a great gradient of oxygen activity of molten steel at the slag–metal interface and in a metal
bath when carbon content in a metal bath is larger than 0.036 pct. The phosphorus in molten steel beneath the slag–metal interface
can be extracted effectively by the comprehensive effect of CaO and Fe
t
O in slags to form 3CaO·P2O5 and 4CaO·P2O5 until the carbon content is less than 0.036 pct during a top–bottom combined blown steelmaking process. 相似文献
10.
The Cu solubility was measured in the CaO-B2O3 and BaO-B2O3 slag systems to understand the dissolution mechanism of Cu in the slags. The Cu solubility had a linear relationship with
oxygen partial pressure in the CaO-B2O3 slag system, which corresponds with previous studies. Also, the Cu solubilities in slag decreased with increasing the slag
basicity, which value of slope was close to –0.5 in logarithmic form. From the results of experiment, the Cu dissolution mechanism
established as follows:
\textCu + \frac14\textO2 = \textCu + + \frac12\textO2 - {\text{Cu}} + \frac{1}{4}{\text{O}}_{2} = {\text{Cu}}^{ + } + \frac{1}{2}{\text{O}}^{2 - } 相似文献
11.
H. B. Fan W. Zheng G. Y. Wang P. K. Liaw J. Shen 《Metallurgical and Materials Transactions A》2011,42(6):1524-1533
An Fe41Co7Cr15Mo14C15B6Y2 bulk metallic glass with a diameter of 5 mm was prepared with the copper-mold-casting method. The corrosion resistance of
this amorphous steel in sulfuric-acid solutions was determined by electrochemical measurements. The passive film formed on
the surface of the alloy after immersion in the 0.5-mol/l H2SO4 solution for 1 week was analyzed by X-ray photoelectron spectroscopy (XPS). Electrochemical measurements show that the corrosion
resistance of the amorphous steel in the 1 mol/l-H2SO4 solution is superior to a stainless steel (SUS 321), and is almost the same as Ti6Al4V, which shows that the amorphous steel
has an excellent corrosion resistance in sulfuric-acid solutions. As the concentration of the sulfuric-acid solutions increases
from 0.5 mol/l to 4 mol/l, the corrosion resistance of the amorphous steel decreases. The XPS result reveals that a bilayer
structure of protective film formed on the surface of the amorphous steel in a H2SO4 solution. The compositions of the inner part of the film are MoO2, Cr2O3, CoO, and FeO, and those of the outer film are MoO3, Cr(OH)3, Co(OH)2, and Fe(OH)3. 相似文献
12.
Fengshan Li Xianpeng Li Shufeng Yang Yanling Zhang 《Metallurgical and Materials Transactions B》2017,48(5):2367-2378
In order to effectively enhance the efficiency of dephosphorization, the distribution ratios of phosphorus between CaO-FeO-SiO2-Al2O3/Na2O/TiO2 slags and carbon-saturated iron (\( L_{\text{P}}^{\text{Fe-C}} \)) were examined through laboratory experiments in this study, along with the effects of different influencing factors such as the temperature and concentrations of the various slag components. Thermodynamic simulations showed that, with the addition of Na2O and Al2O3, the liquid areas of the CaO-FeO-SiO2 slag are enlarged significantly, with Al2O3 and Na2O acting as fluxes when added to the slag in the appropriate concentrations. The experimental data suggested that \( L_{\text{P}}^{\text{Fe-C}} \) increases with an increase in the binary basicity of the slag, with the basicity having a greater effect than the temperature and FeO content; \( L_{\text{P}}^{\text{Fe-C}} \) increases with an increase in the Na2O content and decrease in the Al2O3 content. In contrast to the case for the dephosphorization of molten steel, for the hot-metal dephosphorization process investigated in this study, the FeO content of the slag had a smaller effect on \( L_{\text{P}}^{\text{Fe-C}} \) than did the other factors such as the temperature and slag basicity. Based on the experimental data, by using regression analysis, \( \log L_{\text{P}}^{\text{Fe-C}} \) could be expressed as a function of the temperature and the slag component concentrations as follows: 相似文献
$$ \begin{aligned} \log L_{\text{P}}^{\text{Fe-C}} & = 0.059({\text{pct}}\;{\text{CaO}}) + 1.583\log ({\text{TFe}}) - 0.052\left( {{\text{pct}}\;{\text{SiO}}_{2} } \right) - 0.014\left( {{\text{pct}}\;{\text{Al}}_{2} {\text{O}}_{3} } \right) \\ \, & \quad + 0.142\left( {{\text{pct}}\;{\text{Na}}_{2} {\text{O}}} \right) - 0.003\left( {{\text{pct}}\;{\text{TiO}}_{2} } \right) + 0.049\left( {{\text{pct}}\;{\text{P}}_{2} {\text{O}}_{5} } \right) + \frac{13{,}527}{T} - 9.87. \\ \end{aligned} $$ 13.
Yunqing Ji Chunyang Liu Yan Lu Huixiang Yu Fuxiang Huang Xinhua Wang 《Metallurgical and Materials Transactions B》2018,49(6):3127-3136
The slag composition plays a critical role in the formation of inclusions and the cleanliness of steel. In this study, the effects of FeO content and the C/A (CaO/Al2O3) ratio in the slag on the formation of inclusions were investigated based on a 10-minute slag–steel reaction in a MgO crucible. The FeO content in the top slag was shown to have a significant effect on the formation of MgO·Al2O3 spinel inclusions, and critical content exists; when the initial FeO content in the slag was less than 2 pct, MgO·Al2O3 spinel inclusions formed, and the T.O (total oxygen) was 20 ppm; when the initial FeO content in the slag was more than 4 pct, only Al2O3 inclusions were observed and the T.O was 50 ppm. It was clarified that the main source of Mg for the MgO·Al2O3 spinel inclusion formation was the top slag rather than the MgO crucible. In addition, the cleanliness of the steel increased as the initial FeO content in the top slag decreased. As regards the effects of the C/A ratio, the MgO amount in the observed inclusions gradually increased, whereas the T.O content decreased gradually with the increasing C/A ratio. Slag with a composition close to the CaO-saturated region had the best effect on the inclusion absorption. 相似文献
14.
Kinetics of the reaction of lead slags (PbO-CaO-SiO2-FeO x -MgO) with CO-CO2 gas mixtures was studied by monitoring the changes in the slag composition when a stream of CO-CO2 gas mixture was blown on the surface of thin layers of slags (3 to 10 mm) at temperatures in the range of 1453 K to 1593 K (1180 °C to 1320 °C). These measurements were carried out under conditions where mass transfer in the gas phase was not the rate-limiting step and the reduction rates were insensitive to factors affecting mass transfer in the slag phase. The results show simultaneous reduction of PbO and Fe2O3 in the slag. The measured specific rate of oxygen removal from the melts varied from about 1 × 10?6 to 4 × 10?5 mol O cm?2 s?1 and was strongly dependent on the slag chemistry and its oxidation state, partial pressure of CO in the reaction gas mixture, and temperature. The deduced apparent first-order rate constant increased with increasing iron oxide content, oxidation state of the slag, and temperature. The results indicate that under the employed experimental conditions, the rate of formation of CO2 at the gas-slag interface is likely to be the rate-limiting step. 相似文献
15.
Jie Qi Chengjun Liu Chi Zhang Maofa Jiang 《Metallurgical and Materials Transactions B》2017,48(1):11-16
Aiming at devising new mold flux for Ce-bearing stainless steel, a fundamental investigation on the effect of Ce2O3 on properties of the CaO-Al2O3-Li2O-Ce2O3 slag was provided by the present work. The results show that adding Ce2O3 could decrease the viscosity of the slag due to its effects on decreasing the polymerization of the slag. The crystalline process was restrained by increasing the content of Ce2O3, and the crystalline phases also can be influenced by the slag structure. The crystalline phases were transferred from LiAlO2 and CaO to LiAlO2 and CaCeAlO4 with the addition of Ce2O3 to the slag, which could be well confirmed by the structure of the unit cell of the crystals. 相似文献
16.
Luckman Muhmood Nurni Neelakandan Viswanathan Masanori Iwase Seshadri Seetharaman 《Metallurgical and Materials Transactions B》2011,42(2):274-280
The chemical diffusion coefficient of sulfur in the ternary slag of composition 51.5 pct CaO-9.6 pct SiO2-38.9 pct Al2O3 slag was measured at 1680 K, 1700 K, and 1723 K (1403 °C, 1427 °C, and 1450 °C) using the experimental method proposed earlier
by the authors. The
P\textS2 P_{{{\text{S}}_{2} }} and
P\textO2 P_{{{\text{O}}_{2} }} pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS. The density
of the slag was obtained from earlier experiments. Initially, the order of magnitude for the diffusion coefficient was taken
from the works of Saito and Kawai but later was modified so that the concentration curve for sulfur obtained from the program
was in good fit with the experimental results. The diffusion coefficient of sulfur in 51.5 pct CaO-9.6 pct SiO2-38.9 pct Al2O3 slag was estimated to be in the range 3.98 to 4.14 × 10−6 cm2/s for the temperature range 1680 K to 1723 K (1403 °C to 1450 °C), which is in good agreement with the results available
in literature 相似文献
17.
Masaki Taneike Kota Sawada Fujio Abe 《Metallurgical and Materials Transactions A》2004,35(4):1255-1262
The distributions and precipitated amounts of M23C6 carbides and MX-type carbonitrides with decreasing carbon content from 0.16 to 0.002 mass pct in 9Cr-3W steel, which is used
as a heat-resistant steel, has been investigated. The microstructures of the steels are observed to be martensite. Distributions
of precipitates differ greatly among the steels depending on carbon concentration. In the steels containing carbon at levels
above 0.05 pct, M23C6 carbides precipitate along boundaries and fine MX carbonitrides precipitate mainly in the matrix after tempering. In 0.002
pct C steel, there are no M23C6 carbide precipitates, and instead, fine MX with sizes of 2 to 20 nm precipitate densely along boundaries. In 0.02 pct C steel,
a small amount of M23C6 carbides precipitate, but the sizes are quite large and the main precipitates along boundaries are MX, as with 0.002 pct
C steel. A combination of the removal of any carbide whose size is much larger than that of MX-type nitrides, and the fine
distributions of MX-type nitrides along boundaries, is significantly effective for the stabilization of a variety of boundaries
in the martensitic 9Cr steel. 相似文献
18.
Angelica Sánchez M. Victor Hugo Gutiérrez P. Alejandro Cruz R. Ricardo Gerardo Sánchez A. 《Russian Journal of Non-Ferrous Metals》2016,57(4):316-324
A novel pyrometallurgical route was used to reduce the lead paste to obtain metallic lead with different additions of sodium carbonate at 850°C in a silicon carbide crucible. The process allows to obtain a high recovery of metallic lead in a single step and a slag constituted mainly by lead silicate. Products obtained were characterized by atomic absorption, X-ray powder diffraction and SEM-EDS techniques. A thermodynamic study was carried out with the software FactSage to determinate the compounds formation to the experimental conditions. High amounts of Na2CO3 and SiC promoted the formation of a lead sulfide compound which decreased the lead recovery. 相似文献
19.
Understanding the viscous behavior of copper smelting slags is essential in increasing the process efficiency and obtaining
the discrete separation between the matte and the slag. The viscosity of the FeOt-SiO2-Al2O3 copper smelting slags was measured in the current study using the rotating spindle method. The viscosity at a fixed Al2O3 concentration decreased with increasing Fe/SiO2 ratio because of the depolymerization of the molten slag by the network-modifying free oxygen ions (O2−) supplied by FeO. The Fourier transform infrared (FTIR) analyses of the slag samples with increasing Fe/SiO2 ratio revealed that the amount of large silicate sheets decreased, whereas the amount of simpler silicate structures increased.
Al2O3 additions to the ternary FeOt-SiO2-Al2O3 slag system at a fixed Fe/SiO2 ratio showed a characteristic V-shaped pattern, where initial additions decreased the viscosity, reached a minimum, and increased
subsequently with higher Al2O3 content. The effect of Al2O3 was considered to be related to the amphoteric behavior of Al2O3, where Al2O3 initially behaves as a basic oxide and changes to an acidic oxide with variation in slag composition. Furthermore, Al2O3 additions also resulted in the high temperature phase change between fayalite/hercynite and the modification of the liquidus
temperature with Al2O3 additions affecting the viscosity of the copper smelting slag. 相似文献
20.
The effects of reducing agent, CaF2 content, and reaction temperature upon the silicothermic reduction of MnO in the BaO-MnO-MgO-CaF2 (-SiO2) slags were investigated. Mn recovery was proportional to Si activity in the molten alloy. Moreover, 90 pct yield of Mn recovery was obtained under 5 mass pct CaF2 content and 1873 K (1600 °C) reaction temperature. Increasing CaF2 content above 5 pct yielded little or no further increase in Mn recovery, because it was accompanied by increased slag viscosity owing to the precipitation of high melting point compounds such as Ba2SiO4. 相似文献
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