共查询到20条相似文献,搜索用时 0 毫秒
1.
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
2.
3.
N. P. Fahey D. R. Swinbourne S. Yan J. M. Osborne 《Metallurgical and Materials Transactions B》2004,35(2):197-202
Continuous converting of copper matte based on calcium ferrite slag has many attractions for the copper smelting industry.
However, a serious drawback is that this slag leads to shorter furnace campaigns because it is aggressive toward the magnesia-chromia
refractories that form the furnace lining. As part of an investigation into the causes of this aggressiveness with a view
to devising strategies to mitigate it, the solubility of Cr2O3 in calcium ferrite slag has been determined. The standard drop-quench experimental technique was employed at a temperature
of 1573 K and a relatively high oxygen partial pressure of 3.7×10−4 atm, conditions similar to those used in continuous converting. It was found that approximately 2 wt pct of Cr2O3 can dissolve in calcium ferrite slag under these conditions. The Cr2O3 solubility was found to be unaffected by the Cu2O content of the slag, but may decrease as CaO content decreases. The implications of these findings on the mechanism of attack
of magnesia-chromia refractories by calcium ferrite slag are discussed. 相似文献
4.
5.
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
6.
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
7.
8.
Lars Klemet Jakobsson Gabriella Tranell In-Ho Jung 《Metallurgical and Materials Transactions B》2017,48(1):60-72
NdFeB magnet scrap is an alternative source of neodymium that could have a significantly lower impact on the environment than current mining and extraction processes. Neodymium can be readily oxidized in the presence of oxygen, which makes it easy to recover neodymium in oxide form. Thermochemical data and phase diagrams for neodymium oxide containing systems is, however, very limited. Thermodynamic modeling of the B2O3-FeO-Fe2O3-Nd2O3 system was hence performed to obtain accurate phase diagrams and thermochemical properties of the system. Key phase diagram experiments were also carried out for the FeO-Nd2O3 system in saturation with iron to improve the accuracy of the present modeling. The modified quasichemical model was used to describe the Gibbs energy of the liquid oxide phase. The Gibbs energy functions of the liquid phase and the solids were optimized to reproduce all available and reliable phase diagram data, and thermochemical properties of the system. Finally the optimized database was applied to calculate conditions for selective oxidation of neodymium from NdFeB magnet waste. 相似文献
9.
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
10.
M. BAHGAT M.H. KHEDR M.I. NASR E.K. SEDEEK 《Metallurgical and Materials Transactions B》2007,38(1):5-11
Pure nanocrystalline hematite (40 to 100 nm) compacts were prepared and sintered at various temperatures (300 °C to 600 °C)
and then reduced with 100 pct H2 at 500 °C. On the other hand, fired compacts at 500 °C were reduced with a H2-Ar gas mixture containing different concentration of hydrogen (100, 75, 50, and 25 pct) at 500 °C using thermogravimetric
techniques. Nanocrystalline Fe2O3 compacts were characterized before and after reduction with X-ray diffraction, scanning electron microscopy (SEM), vibrating
sample magnetometer (VSM), and reflected light microscope. It was found that the fired compacts at 400 °C to 600 °C have relatively
faster reaction behaviors compared to that at lower firing temperature 300 °C. By decreasing the firing temperature to 300 °C,
partial sintering with grain growth was observed clearly during reduction. Also, it was found that the reduction rate increased
with increasing hydrogen content in the reducing gas. Comparatively, grain growth and partial coalescence took place during
reduction with 25 pct H2 due to long reaction time.
11.
Vinay Pratap Singh Anjan Sil R. Jayaganthan 《Transactions of the Indian Institute of Metals》2012,65(1):1-12
An ever increasing demand for high-performance ceramic coatings has made it inevitable for developing techniques with precise
control over the process parameters to enable the fabrication of coatings with the desired microstructure and improved structural
properties. The literature on plasma sprayed nanostructured ceramic coatings such as of Al2O3, Cr2O3, and their composites obtained using reconstituted nano sized ceramic powders has been reviewed in this study. Ceramic coatings
due to their enhanced properties are on the verge of replacing conventional ceramic coatings used for various applications
like automotive systems, boiler components, power generation equipment, chemical process equipment, aircraft engines, pulp
and paper processing equipment, land-based and marine engine components, turbine blades etc. In such cases, the advantage
is greater longevity and reliability for realizing the improved performance of ceramic coatings. It has been observed that
the plasma sprayed nanostructured ceramic coatings show improvement in resistance to wear, erosion, corrosion, and mechanical
properties as compared to their conventional counterparts. This article reviews various aspects concerning the plasma sprayed
ceramic coatings such as (i) the present understanding of formation of plasma-spray coatings and factors affecting them, (ii)
wear performance of nanostructured Al2O3, Cr2O3 and their composite ceramic coatings in comparison to their conventional counterparts, and (iii) mechanisms of wear observed
for these coatings under various conditions of testing. 相似文献
12.
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
13.
Yunshu Zhang Xiaoxia Wu Robert A. Rapp 《Metallurgical and Materials Transactions B》2004,35(1):133-141
Experiments to measure the solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 were performed, and the results confirmed existing literature values. The solubilities of NiAl2O4 and FeAl2O4 in Al2O3-saturated cryolite melts at 1300 K were modeled thermodynamically in terms of the Ni-containing complexes Na2NiF4 and Na4NiF6, and the Fe-containing solutes FeF2, Na2FeF4, and Na4FeF6. The experimental solubility data were fitted to multiple simultaneous equilibria. Equilibrium constants and ΔG
f
0
values for the formation reactions of the these solutes were thereby estimated. The solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 and solute distributions in Al2O3-undersaturated cryolite melts were calculated for a number of melt compositions from the present model. The existence of
several competitive solute species is inherent to highly buffered ionic cryolite solutions where the traditional log-log methodology
had previously failed to identify dominant single solutes. In such solutions, individual solutes of oxides are not likely
to dominate over a wide composition range so that a more global modeling is required. The principal solute species identified
in the present study exhibit reasonable three-dimensional (3-D) anion geometries. 相似文献
14.
In-Ho Jung Youn-Bae Kang Sergei A. Decterov Arthur D. Pelton 《Metallurgical and Materials Transactions B》2004,35(2):259-268
All available thermodynamic and phase-diagram data have been critically evaluated and optimized for the liquid-slag phase
and for all solid phases at 1 bar pressure from 298 K to above the liquidus temperatures for the systems MnO-Al2O3 and MnO-Al2O3-SiO2, and a database of model parameters has been prepared. The modified quasichemical model was employed for the molten-slag
phase. Calculations using the database were performed with applications to inclusion engineering for Mn/Si killed steel. 相似文献
15.
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
16.
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
|
设为首页 | 免责声明 | 关于勤云 | 加入收藏 |
Copyright©北京勤云科技发展有限公司 京ICP备09084417号 |