共查询到20条相似文献,搜索用时 46 毫秒
1.
Hiroyuki Fukuyama Hideki Tabata Kazuhiro Nagata 《Metallurgical and Materials Transactions B》2003,34(3):307-311
The standard Gibbs energy change for the following reaction has been directly determined by electromotive force (EMF) measurement
using CaF2 as the solid electrolyte in the temperature range from 1313 to 1329 K.
From the preceding results, the standard Gibbs energy of formation of cuspidine has been evaluated for the first time as
The chemical potential diagram for the CaO-SiO2-CaF2 system has been developed at 1323 K based on the thermodynamic data obtained in the present study. 相似文献
2.
G. M. Kale 《Metallurgical and Materials Transactions B》1998,29(1):31-38
Gibbs energy of formation of NiTiO3 (ilmenite) relative to its component oxides, NiO (rock salt) and TiO2 (rutile), has been measured employing the solid-state electrochemical cell,
. between 994 and 1371 K. The open-circuit electromotive force (emf) of the preceding solid-state galvanic cell was found
to be reversible and to vary linearly as a function of temperature in the range of measurement. The results obtained in this
study give for the reaction
. Combining the Gibbs energy of formation of NiTiO3 (ilm) from the component oxides with that for the formation of NiO (rs) from its elements gives for the reaction
. Differential thermal analysis (DTA) of NiTiO3 (ilm) between 373 and 1623 K indicated that NiTiO3 (ilm) undergoes a reversible order-disorder phase transformation between 1540 and 1594 K. Based on the ideal mixing of cations
on the cationic sublattice of NiTiO3 (ilm) and a critical phase transformation of 1568 K obtained from the DTA, the Gibbs energy change for the order-disorder
phase transformation in NiTiO3 (ilm) is obtained as
. 相似文献
3.
Ernest W. Dewing 《Metallurgical and Materials Transactions B》1997,28(6):1095-1097
Earlier data are recalculated to give the boundaries of the homogeneous field of solid cryolite. The equilibrium constant
where the composition of the material is (3−x)NaF · AlF3, is
The activity of NaF, a
NaF, is referred to the solid standard state. The standard Gibbs energy of fusion of stoichiometric cryolite is
相似文献
4.
The dissolution equilibrium of calcium vapor in liquid iron was carried out at 1873 K in a two-temperature zone furnace using
a vapor-liquid equilibration method. A sealed Mo reaction chamber and a self-made CaO crucible were used in this study. The
thermodynamic parameters obtained are as follows.
For reaction Ca (g)=[Ca],
The relation between dissolved calcium in liquid iron and calcium vapor can be expressed as
The interaction parameters of third elements on calcium determined at 1873 K are as follows:
相似文献
5.
Data in the literature on the Magneli oxides of titanium have been critically evaluated and equations have been developed
from these data for the standard-state Gibbs energy of formation of the following oxides: Ti4O7, Ti5O9, Ti6O11, Ti8O15, and Ti9O17. Examination of those data yielded the following:
Similar equations for Ti16O31 and Ti50O99 have been estimated from their respective data at 1304 K. The result of that analysis has lead to the following equations:
These equations, along with data in the literature, have been used to construct the Ti-O stability diagram. 相似文献
6.
Koichiro Koyama Masao Morishita Tomohiro Harada Nobuyuki Maekawa 《Metallurgical and Materials Transactions B》2003,34(5):653-659
The standard Gibbs energies of formation of Fe2Mo3O12, Fe2Mo3O8, FeMoO4, and Fe2MoO4 of the Fe-Mo-O ternary system and the μ phase of the Fe-Mo binary system have been determined by measuring electromotive forces of galvanic cells having an Y2O3-stabilized ZrO2 solid electrolyte. The results are as follows: $$\begin{gathered} \Delta _f G^\circ (FeMoO_4 )/kJ \cdot mol^{ - 1} = - 1053.5 + 0.2983(T/K) \pm 0.4 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_8 )/kJ \cdot mol^{ - 1} = - 2347 + 0.6814(T/K) \pm 1 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_{12} )/kJ \cdot mol^{ - 1} = - 2993 + 0.9105(T/K) \pm 2 \hfill \\ Temperature range: 1040 to 1145 K \hfill \\ \Delta _f G^\circ (Fe_{0.58} Mo_{0.42} )/kJ \cdot mol^{ - 1} = - 18.7 + 0.0117(T/K) \pm 0.1 \hfill \\ Temperature range: 1162 to 1223 K \hfill \\ \Delta _f G^\circ (Fe_2 MoO_4 )/kJ \cdot mol^{ - 1} = - 1174 + 0.342(T/K) \pm 1 \hfill \\ Temperature range: 1243 to 1466 K \hfill \\ \end{gathered} $$ where the standard pressure is 1 bar (100 kPa). 相似文献
7.
Victor T. Witusiewicz Ferdinand Sommer 《Metallurgical and Materials Transactions B》2000,31(2):277-284
The partial (Δ
and the integral (ΔH) enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys have been determined by high-temperature isoperibolic calorimetry
at 1565 ± 5 K. The heat capacity (C
p) of liquid Ni26Zr74 has been measured by adiabatic calorimetry (C
p=53.5±2.2 J mol−1 K−1 at 1261±15 K). The integral enthalpy of mixing changes with composition from a small positive (Cu-Ni, ΔH (x
Ni=0.50, T=1473 to 1750 K)=2.9 kJ mol−1) to a moderate negative (Cu-Zr; ΔH(x
Zr=0.46, T=1485 K)=−16.2 kJ mol−1) and a high negative value (Ni-Zr; ΔH(x
Zr=0.37, T=1565 K)=−45.8 kJ mol−1). Regression analysis of new data, together with the literature data for liquid Ni-Zr alloys, results in the following relationships
in kJ mol−1 (standard states: Cu (1), Ni (1), and Zr (1)):for Ni-Zr (1281≤T≤2270 K),
for Cu-Ni-Zr (T=1565±5 K),
相似文献
8.
Hideki Ono-Nakazato Kenji Taguchi Tateo Usui Keishi Tamura Yuuji Tomatsu 《Metallurgical and Materials Transactions B》2001,32(6):1113-1118
The standard Gibbs energies of formation of Cr2N and CrN have been measured by an equilibration technique and by using thermogravimetry and differential thermal analysis
(TG-DTA) at temperatures ranging from 1232 to 1523 K. The results are expressed as follows:
The standard Gibbs energies of formation of Cr2N and CrN determined by the present work are more negative than the values in the JANAF Tables by about 14 and 5 kJ/mol, respectively,
in the measured temperature range. 相似文献
9.
10.
L. D. Teng K. G. Lu R. E. Aune S. Seetharaman 《Metallurgical and Materials Transactions A》2004,35(12):3673-3680
The Gibbs energies of formation for Cr3C2,
, have been obtained from electromotive force (EMF) measurements, in the temperature range 950 to 1150 K, using the following
galvanic cells with CaF2 single crystals as the electrolyte:
Extreme precautions were taken during the experimental measurements to avoid errors. The reliability and reproducibility
of the values were confirmed by careful repetition of several of the experiments. The following equation has been obtained
by a linear analysis of the EMF results as a function of temperature:
The generated values are compared with those reported in the literature.
The values of the enthalpy of formation were evaluated by using a third-law analysis, and an average value of Δ
f
H°298=−71.7 kJ/mol was obtained. The ground-state energy of the hypothetic end-member compound CrC3 in the bcc structure at 0 K was calculated by using the ab initio method. The experimental results obtained, as well as the results from the ab initio calculations, were employed in a reassessment of the Cr-C system using the CALPHAD approach. A new set of parameters for
the bcc phase was evaluated using first-principles calculations. 相似文献
11.
Dae-Hee Woo Youn-Bae Kang Hae-Geon Lee 《Metallurgical and Materials Transactions B》2002,33(6):915-920
The liquid MnO-SiO2-Al2O3 system was studied at 1823 K by equilibrating MnO-SiO2-Al2O3 melts of different compositions with Pt-Mn alloys and an oxygen-bearing gas phase. Liquid compositions for cristobalite saturation
were determined at 1823 K. A new liquidus for the cristobalite primary field is proposed. The activity of Mn in the Pt-Mn
alloy at 1823 K can be represented by the following equation:
The MnO activity was measured in different melt compositions, and MnO isoactivity lines were determined. It was found that
the MnO activity is relatively insensitive to the SiO2/Al2O3 ratio, but increases sharply above the MnO mole fraction of 0.5. In the low-MnO-concentration range (α
MnO <0.15), the quadratic formalism expressed by the following equation is proposed to represent the MnO activity:
If the MnO activity exceeds the aforementioned limit, the modified quasi-chemical model is recommended. 相似文献
12.
13.
Mitsuru Tanahashi Kunihiko Takeda Zhijian Su Hong Yong Sohn Chikabumi Yamauchi 《Metallurgical and Materials Transactions B》2003,34(6):869-879
The rate of Sb elimination from molten copper by the use of Na2CO3 slag was measured at 1523 K. The results obtained under the present experimental conditions show that Sb in molten copper
is eliminated in a tri-valent or a penta-valent form, depending on the oxygen concentration at the slag-metal interface, and
its elimination rate increases with increasing initial oxygen concentration in molten copper. The overall elimination rate
of Sb is affected by the stirring condition of the molten copper, which indicates a rate control by mass transfer in that
phase. The mass-transfer coefficients of Sb and oxygen in molten copper at 1523 K without external stirring were determined,
respectively, to be
based on the mass balances of Sb and oxygen in the molten copper and slag phases and the equilibrium relation of the Sb elimination
reaction at the slag-metal interface. 相似文献
14.
Tomohito Shimpo Takeshi Yoshikawa Kazuki Morita 《Metallurgical and Materials Transactions B》2004,35(2):277-284
The interaction between calcium and phosphorus in molten silicon was investigated for predicting the removal of phosphorus
from silicon by an acid leaching treatment with calcium addition. In the present study, two immiscible liquids of silicon
and lead were equilibrated, and the interaction parameter between calcium and phosphorus and the self-interaction parameter
of phosphorus in molten silicon at 1723 K were determined.
In the derivation process, the following activity coefficients and the interaction parameters of metallic impurities in molten
silicon and lead at 1723 K were also obtained:
The effect of the calcium addition to silicon improves the subsequent removal of phosphorus in the acid leaching treatment,
and the increase in removal fraction of phosphorus was observed remarkably with the addition of calcium in silicon. 相似文献
15.
Spontaneous fluoride emissions from high-temperature processes can result in an increased atmospheric fluorine content and
environmental contamination. Slags containing SiO2, Na2O, and CaF2 tend to be unstable at high temperatures, and gaseous species such as NaF and SiF4 evolve simultaneously. Furthermore, a reaction between NaF and SiF4 can occur to produce Na2SiF6 (sodium hexafluorosilicate), the behavior and properties of which are not well established. In a previous study, the diffusivity
of NaF in argon, nitrogen, and helium was measured. In this study, the rate of NaF vaporization in a SiF4-Ar atmosphere was investigated and the rates of formation and dissociation of Na2SiF6 were measured.
Kinetic analyses were carried out and the rate constants of the formation and dissociation of Na2SiF6 were obtained. The rate equation for Na2SiF6 formation was expressed as follows:
and the temperature dependences of k
c1 and k
c2 were
相似文献
16.
Hideki Ono Masaya Nakahata Fumitaka Tsukihashi Nobuo Sano 《Metallurgical and Materials Transactions B》1993,24(3):487-492
The standard Gibbs energy of formation of MgO was determined from the measurement of the ΔG° for the reaction
; by equilibrating Mg and Nb with a magnesia crucible and is expressed as follows: Mg(l)+ l/2O2(g) = MgO(s) ΔG° = −657,000(±5000) + 141(±13)T [J/mol] (973 to 1323 K)
The standard Gibbs energies of formation of SrO and BaO were determined by equilibrating silver and MO(M: Sr, and Ba) in a
graphite crucible on the basis of the reactionM(in Ag) + CO (g) = MO (s) + C (s), yielding the following results:
相似文献
17.
Takahiro Miki Kazuki Morita Nobuo Sano 《Metallurgical and Materials Transactions B》1998,29(5):1043-1049
The thermodynamic properties of aluminum, magnesium, and calcium in molten silicon were investigated using a chemical equilibration
technique at 1723 to 1848 K, 1698 to 1798 K, and 1723 to 1823 K, respectively. The activity coefficient of aluminum in molten
silicon was determined by equilibrating molten silicon-aluminum alloys with solid Al2O3 and Al6Si2O13, that of magnesium was determined by equilibrating molten silicon-magnesium alloys and MgO-SiO2-Al2O3 melts doubly saturated with MgSiO3 and SiO2, and that of calcium was determined by equilibrating molten silicon-calcium alloys with SiO2-saturated CaO-SiO2 melts. The activity coefficients at infinite dilution relative to the pure liquid state were determined as follows:
18.
J. M. Osborne W. J. Rankin D. J. McCarthy D. R. Swinbourne 《Metallurgical and Materials Transactions B》2001,32(1):37-45
The kinetics of oxidation of zinc vapor in the Zn-CO-CO2-N2 system was investigated for zinc partial pressures of 0.01 to 0.09 atm, carbon monoxide partial pressures up to 0.5 atm,
and carbon dioxide partial pressures up to 0.6 atm at 730 °C to 900 °C. The experimental apparatus consisted of a flow reactor
and a multitemperature zone furnace. Known gas compositions were generated and the rate of oxidation of zinc vapor was determined
from the mass of zinc oxide deposited under controlled conditions. The rate of oxidation of zinc was found to be a function
of temperature and of the partial pressures of zinc, carbon monoxide, and carbon dioxide. It was autocatalytic with respect
to carbon monoxide and independent of the total mass of zinc oxide deposited. The reactions occurring in parallel for this
mechanism are
19.
This article describes kinetic modeling of titania reduction and carburization by methane-containing gas, based on experimental
data reported previously by Zhang and Ostrovski. A sequence of titania reduction to titanium oxycarbide,
20.
K. T. Jacob Shashank Priya Yoshio Waseda 《Metallurgical and Materials Transactions A》1998,29(6):1545-1550
The activity of rhodium in solid Pt-Rh alloys is measured in the temperature range from 900 to 1300 K using the solid-state
cell
|