共查询到20条相似文献,搜索用时 31 毫秒
1.
Ramaraghavulu Rajavaram Hyelim Kim Chi-Hoon Lee Won-Seung Cho Chi-Hwan Lee Joonho Lee 《Metallurgical and Materials Transactions B》2017,48(3):1595-1601
The effect of Al2O3 concentration on the density and structure of CaO-SiO2-Al2O3 slag was investigated at multiple Al2O3 mole percentages and at a fixed CaO/SiO2 ratio of 1. The experiments were conducted in the temperature range of 2154 K to 2423 K (1881 °C to 2150 °C) using the aerodynamic levitation technique. In order to understand the relationship between density and structure, structural analysis of the silicate melts was carried out using Raman spectroscopy. The density of each slag sample investigated in this study decreased linearly with increasing temperature. When the Al2O3 content was less than 15 mole pct, density decreased with increasing Al2O3 content due to the coupling of Si (Al), whereas above 20 mole pct density of the slag increased due to the role of Al3+ ion as a network modifier. 相似文献
2.
The glass series with general formula 15 Li2O–(85 − x) B2O3–x La2O3 was prepared. Electrical and optical properties of these glasses were studied. It is observed that the conductivity of these
glasses decreases while density, glass transition temperature and refractive index increases with the addition of La2O3. Ion concentration of La3+ in glasses, polaron radius, field strength, molar refractivity and molar electronic polarizability were calculated. The absorption
coefficient and direct optical band gaps are evaluated using the absorption edge calculations. The different factors that
play a role for controlling the refractive indices such as electronic polarizability, field strength of cations and rigidity
of glass structure are discussed in accordance with the obtained index data. 相似文献
3.
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
4.
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
5.
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
6.
In an attempt to systematize the knowledge of the heat conduction of liquid silicates, the effective thermal diffusivities
of some synthetic slags containing CaO, Al2O3, and SiO2 have been measured, using the three-layer laser-flash method on a differential scheme in the temperature range of 1625 to
1825 K. The effective thermal diffusivities measured, which are a combination of the phononic and photonic heat-transfer mechanisms,
were found to increase with increasing temperature for all the presently investigated slags. The slag compositions were chosen
in such a way that the changes in the effective thermal diffusivities would reflect the changes in the structure of the slags.
It was observed that, at a CaO/Al2O3 molar ratio of 4.42, an increase of the SiO2 content had very little effect on the effective thermal diffusivity values. On the other hand, addition of SiO2 to a slag with the CaO/Al2O3 molar ratio of 2.59 resulted in a significant increase in the effective thermal diffusivity. The addition of Al2O3 to slags with a constant CaO/SiO2 molar ratio resulted in a marked increase in the effective thermal diffusivity. Both these trends indicate that there might
be an influence of the network formation in silicate melts on the effective thermal diffusivity. 相似文献
7.
8.
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
9.
T. F. Grigor’eva I. A. Vorsina A. P. Barinova S. V. Tsybulya O. A. Bulavchenko N. Z. Lyakhov 《Russian Metallurgy (Metally)》2009,(4):351-356
The mechanochemical preparation of nickel aluminide/corundum (Ni
x
Al
y
/Al2O3) powder nanocomposites is shown to be possible during the mechanochemical aluminum reduction of nickel oxide at various weight
proportions of the components. 相似文献
10.
Yunkyum Kim Minsoo Shin Chengying Tang Joonho Lee 《Metallurgical and Materials Transactions B》2010,41(4):872-875
The wettability of MnxSiyOz by liquid Zn-Al alloys was investigated to obtain basic information on the coating properties of high-strength steels with
surface oxides in the hot-dip galvanizing process. In this study, the contact angles of liquid Zn-Al alloys (Al concentrations
were 0.12 and 0.23 wt pct) on four different MnxSiyOz oxides, namely MnO, MnSiO3, Mn2SiO4, and SiO2, were measured with the dispensed drop method. The contact angle did not change across time. With an increasing Al concentration,
the contact angle was slightly decreased for MnO and Mn2SiO4, but there was no change for MnSiO3 and SiO2. With an increasing SiO2 content, the contact angle gradually increased by 54 wt pct to form MnSiO3, and for pure SiO2 substrate, the contact angle decreased again. Consequently, the MnSiO3 substrate showed the worst wettability among the four tested oxide substrates. 相似文献
11.
Ghasem Roghani Evgueni Jak Peter Hayes 《Metallurgical and Materials Transactions B》2003,34(2):173-182
Phase-equilibrium data and liquidus isotherms for the system “MnO”-CaO-(Al2O3+SiO2) at silicomanganese alloy saturation have been determined in the temperature range of 1373 to 1723 K. The results are presented
in the form of the pseudoternary sections “MnO”-CaO-(Al2O3+SiO2) with Al2O3/SiO2 weight ratios of 0.55 and 0.65. The primary-phase fields have been identified in this range of conditions. 相似文献
12.
K. B. Bakin O. N. Simakova P. V. Polyakov Yu. G. Mikhalev D. A. Simakov A. O. Gusev 《Russian Metallurgy (Metally)》2010,(8):707-711
The electrical conductivity of NaF-AlF3-Al2O3 melts with a CaF2 concentration of 5 wt % is measured at a continuously varying cell constant when the molar cryolitic ratio CR = [NaF]/[AlF3] changes from 1.2 to 2.0 [1, 2]. The experimental data are used to obtain a regression equation to describe the dependence
of the electrical conductivity of the melts under study on CR, the alumina content, and temperature {χ] = f(CR, [Al2O3], T)}. 相似文献
13.
A thermodynamic equilibrium between the Fe-16Cr melts and the CaO-Al2O3-MgO slags at 1823 K as well as the morphology of inclusions was investigated to understand the formation behavior of the
MgO-Al2O3 spinel-type inclusions in ferritic stainless steel. The calculated and observed activities of magnesium in Fe-16Cr melts
are qualitatively in good agreement with each other, while those of aluminum in steel melts exhibit some discrepancies with
scatters. In the composition of molten steel investigated in this study, the log (X
MgO/X
Al
2O3) of the inclusions linearly increases by increasing the log [a
Mg/a
Al
2
·a
O
2
] with the slope close to unity. In addition, the relationship between the log (X
MgO/X
Al
2O3) of the inclusions and the log (a
MgO/a
Al
2O3) of the slags exhibits the linear correlation with the slope close to unity. The compositions of the inclusions are relatively
close to those of the slags, viz. the MgO-rich magnesia-spinel solid solutions were formed in the steel melts equilibrated with the highly basic slags saturated
by CaO or MgO. The spinel inclusions nearly saturated by MgO were observed in the steel melts equilibrated with the slags
doubly saturated by MgO and MgAl2O4. The spinel and the Al2O3-rich alumina-spinel solid solutions were formed in the steel melts equilibrated with the slags saturated by MgAl2O4 and MgAl2O4-CaAl2O4 phases, respectively. The apparent modification reaction of MgO to the magnesium aluminate inclusions in steel melts equilibrated
with the highly basic slags would be constituted by the following reaction steps: (1) diffusion of aluminum from bulk to the
metal/MgO interface, (2) oxidation of the aluminum to the Al3+ ions at the metal/intermediate layer interface, (3) diffusion of Al3+ ions and electrons through the intermediate layer, and (4) magnesium aluminate (MgAl2O4 spinel, for example) formation by the ionic reaction. 相似文献
14.
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
15.
Joo Hyun Park Sang-Beom Lee Henri R. Gaye 《Metallurgical and Materials Transactions B》2008,39(6):853-861
16.
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
$$ \begin{aligned} \log L_{\text{P}}^{\text{Fe-C}} & = 0.059({\text{pct}}\;{\text{CaO}}) + 1.583\log ({\text{TFe}}) - 0.052\left( {{\text{pct}}\;{\text{SiO}}_{2} } \right) - 0.014\left( {{\text{pct}}\;{\text{Al}}_{2} {\text{O}}_{3} } \right) \\ \, & \quad + 0.142\left( {{\text{pct}}\;{\text{Na}}_{2} {\text{O}}} \right) - 0.003\left( {{\text{pct}}\;{\text{TiO}}_{2} } \right) + 0.049\left( {{\text{pct}}\;{\text{P}}_{2} {\text{O}}_{5} } \right) + \frac{13{,}527}{T} - 9.87. \\ \end{aligned} $$
17.
Density measurements of a low-silica CaO-SiO2-Al2O3 system were carried out using the Archimedes principle. A Pt 30 pct Rh bob and wire arrangement was used for this purpose.
The results obtained were in good agreement with those obtained from the model developed in the current group as well as with
other results reported earlier. The density for the CaO-SiO2 and the CaO-Al2O3 binary slag systems also was estimated from the ternary values. The extrapolation of density values for high-silica systems
also showed good agreement with previous works. An estimation for the density value of CaO was made from the current experimental
data. The density decrease at high temperatures was interpreted based on the silicate structure. As the mole percent of SiO2 was below the 33 pct required for the orthosilicate composition, discrete
\textSiO44 - {\text{SiO}}_{4}^{4 - } tetrahedral units in the silicate melt would exist along with O2– ions. The change in melt expansivity may be attributed to the ionic expansions in the order of
\textAl 3+ - \textO 2- < \textCa 2+ - \textO 2- < \textCa 2+ - \textO - {\text{Al}}^{ 3+ } - {\text{O}}^{ 2- } < {\text{Ca}}^{ 2+ } - {\text{O}}^{ 2- } < {\text{Ca}}^{ 2+ } - {\text{O}}^{ - } 相似文献
18.
Christian Thales Mutale Alan W. Cramb Thomas Claudon 《Metallurgical and Materials Transactions B》2005,36(3):417-418
In this work, isothermal crystallization of a synthetic slag containing 46 wt pct CaO, 46 wt pct SiO2, 6 wt pct Al2O3, and 2 wt pct Na2O has been investigated by means of double hot thermocouple technique (DHTT). The effect of Na2O content on crystallization time was confirmed. Two different types of calcium silicate crystals were observed. Calcium di-silicate
forms at temperatures above 1150 °C and calcium tri-silicate precipitate at temperatures below 1050 °C. A mixture of the two
types of calcium silicate has been observed between the two temperatures. The tendency of crystals to become richer in calcium
at low temperatures that has also been observed in previous published works has been confirmed. No effect of the cooling rate
on crystallization start time was confirmed in the range of cooling rates applied in this investigation. 相似文献
19.
J. L. Santos R. L. S. B. Marçal P. R. R. Jesus A. V. Gomes E. P. LimaJr. S. N. Monteiro J. B. de Campos L. H. L. Louro 《Metallurgical and Materials Transactions A》2017,48(10):4432-4440
Different amounts of LiF were added to an Al2O3-4 pct Nb2O5 basic ceramic, as sintering agent. Improved new ceramics were obtained with LiF concentrations varying from 0.25 to 1.50 wt pct and three sintering temperatures of 1573 K, 1623 K, and 1673 K (1300 °C, 1350 °C, and 1400 °C). The addition of 0.5 wt pct LiF yielded the highest densification, 94 pct of the theoretical density, in association with a sintering temperature of 1673 K (1400 °C). Based on X-ray diffraction (XRD), this improvement was due not only to the presence of transformed phases, more precisely Nb3O7F, but also to the absence of LiAl5O8. The preferential interaction of LiF with Nb2O5, instead of Al2O3, contributed to increase the alumina sintering ability by liquid phase formation. Scanning electron microscopy (SEM) results revealed well-connected grains and isolated pores, whereas the chemical composition analysis by energy dispersive energy (EDX) indicated a preferential interaction of fluorine with niobium, in agreement with the results of XRD. It was also observed from thermal analysis that the polyethylene glycol binder burnout temperature increased for all LiF concentrations. This may be related to the formation of hydrogen bridge bonds. 相似文献
20.
In-situ Al2O3/TiAl3 intermetallic matrix composites were fabricated via squeeze casting of TiO2/A356 composites heated in the temperature range from 700 °C to 780 °C for 2 hours. The phase transformation in TiO2/A356 composites employing various heat-treatment temperatures (700 °C to 780 °C) was studied by means of differential thermal
analysis (DTA), microhardness, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction
(XRD). From DTA, two exothermic peaks from 600 °C to 750 °C were found in the TiO2/A356 composites. The XRD showed that Al2O3 and TiAl3 were the primary products after heat treatment of the TiO2/A356 composite. The fabrication of in-situ Al2O3/TiAl3 composites required 33 vol pct TiO2 in Al and heat treatment in the range from 750 °C to 780 °C. The hardness (HV) of the in-situ Al2O3/TiAl3 composites (1000 HV) was superior to that of nonreacted TiO2/A356 composites (200 HV). However, the bending strength decreased from 685 MPa for TiO2/A356 composites to 250 MPa for Al2O3/TiAl3 composites. It decreased rapidly because pores occurred during the formation of Al2O3 and TiAl3. The activation energy of the formation of Al2O3 and TiAl3 from TiO2 and A356 was determined to be about 286 kJ/mole. 相似文献
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