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1.
The distribution ratio of zinc between Ag‐Zn and Fe‐Zn alloys was measured to clarify the thermodynamic behaviour of zinc in Fe‐C melt at high temperatures. Also, the distribution ratio between Ag‐Zn alloy and CaO‐FeO‐CaF2 slag was measured to understand the dissolution mechanism of zinc in molten slags. The activity coefficient of zinc in Ag‐Zn alloy was preliminarily measured as a fundamental thermodynamic data for the activity of zinc in Fe‐C melt. From the dependence of the activity coefficient of zinc in Fe‐C melts on temperature and carbon content, the following equation could be obtained at 1473 ‐ 1623 K: The distribution ratio of zinc between Ag‐Zn alloy and CaO‐FeO‐CaF2 slag increased by increasing both the oxygen potential and slag basicity. The stoichiometric coefficients of the dissolution reaction were obtained by considering the relationship between zinc distribution ratio and slag basicity or oxygen partial pressure, when one of these two independent variables was fixed. The dissolution reaction of zinc into the slags could be described as follows:   相似文献   

2.
The present work presents mathematical model for the estimation of sulphide capacities. The sulphide capacity, CS is expressed as (1) where ΔG0 is the standard Gibbs energy change for the reaction, (2) ξ, being a function of both temperature and composition, is characterized by the system under consideration. By optimizing ξ, the sulphide capacities could be estimated as functions of temperature and composition. The slag composition is described using a modified Temkin approach, where complex polymeric ions are considered as dissociated to simple species. The model has been applied to the binary systems CaO-SiO2, MnO-SiO2 as well as the CaO-MnO-SiO2 ternary system. The results show that reliable predictions of the sulphide capacities can be obtained using the present model.  相似文献   

3.
4.
A magnesia capacity is defined, CMg2+ = (%Mg2+)/aMgO and its relation to optical basicity is examined and discussed. The solubility of MgO in complex slags, in equilibrium with magnesiowustite, is derived from the activity of MgO in the magnesiowustite and from the magnesia capacity as given by the slag's optical basicity. It is found that the activity of MgO in the magnesiowustite can be derived from [%O] assuming ideality in the FeO–MgO system at 1600°C. It is also found that the MgO saturation contents in complex slags are accurately derived from the equation: In addition, the relation between the magnesia capacity and the capacities of vanadium and phosphorus is examined and the relative basicity of the oxides is discussed.  相似文献   

5.
On the basis of linear nonequilibrium thermodynamics, the connection between diffusivity and activity interaction coefficients in melts was delineated and this relation can be expressed as the following mathematic formula: (1)  相似文献   

6.
The equilibrium experiments on liquid Fe-Ca-Xi were carried out in a high pressure induction furnace in dense CaO crucibles. The solubility of calcium, saturated with CaO, in iron was determined as a function of temperature under 10 bar argon pressure. In pure iron the maximum solubility of calcium at 1 600°C is 0.03 wt.%. The alloying elements silicon, aluminium and nickel remarkably increase the calcium solubility in iron, whereas manganese causes an almost negligible increase. Chromium significantly reduces calcium solubility. The opposite influence of chromium and nickel on calcium solubility is balanced in an 18/8 steel. The interaction parameters of the alloying elements in the solvent iron with respect to Raoultian standard state are as follows:   相似文献   

7.
Foils made from pure iron with a porous structure were nitrided in mixtures of pure and entirely decomposed ammonia until constant weight was reached. The relationship between nitriding potential, temperature and concentration was measured in the ε region between 350 and 725°C and at concentrations between and . This relationship can be mathematically represented, if the ε phase is considered to be a subregular solution of nitrogen in hexagonal iron. From the Gibbs free energy of the nitrogen in the gas phase, the numerical relation and the parameters L′ = ? 600 000 + 775.6 T J/mole L″ = 1270000 ? 1423 T J/mole are deduced. The results of a calculation of the (γ + ε)/ε phase boundary using this equations are in accordance with an experimental measurement.  相似文献   

8.
Es wurde eine Fe-80 Gew.ppm-N-Legierung nach verschiedenen Anlaßbehandlungen mit Hilfe der magnetischen Nachwirkung untersucht, um den Effekt der Ausscheidungsstruktur auf die schon früher gefundenen Relaxationsprozesse6) bis 8) zu bestimmen. Es wurden zwei Prozesse gefunden: I. Diffusion im Spannungsfeld der Ausscheidung mit den mittleren Aktivierungsparametern Die Atome im Spannungsfeld erreichen ihre Gleichgewichtslage durch weitreichende Diffusion. Da dieser Effekt – ähnlich der hydrostatischen Relaxation bei Koiwa26) – nur bei bestimmten geometrischen Konfigurationen der Blochwände und der spontanen Magnetisierung stattfindet und außerdem die Diffusion durch Versetzungen behindert werden kann, verschwindet diese Relaxation bei zunehmender Ausscheidungsgröße. Sie geht dann über in einen zweiten Reorientierungsprozeß, der im Spannungsfeld abläuft. Dieser hat wegen der Wechselwirkung mit den Versetzungen eine im Vergleich zur Richter-Nachwirkung erhöhte Aktivierungsenergie (1,10 eV). Für die Bindungsenergie der Stickstoffatome an die Oberfläche der Ausscheidungen findet man Werte im Bereich 0,3 … 0,5 eV, wobei die Stärke der Bindung mit wachsender Ausscheidungsgröße zunimmt. Dies weist darauf hin, daß die Versetzungen die Ausscheidungsoberfläche stabilisieren. II. Reorientierung der Stickstoffatome in der Randzone der Ausscheidung mit den mittleren Aktivierungsparametern Die Aktivierungsparameter werden von der Ausscheidungsstruktur kaum beeinflußt, ihre Verteilungen werden jedoch bei stabilisierten Ausscheidungen schärfer.  相似文献   

9.
The surface reaction of the carburization and decarburization of α-iron in CH4/H2-mixtures has been investigated by a method using the radioactive isotope 14C. Experimentally two different kinetic equations have been confirmed and discussed in detail: In accordance to 1) the kinetic equation (1) is explained by a slow reaction: . For the kinetic equation (2) the adsorption, respectively the desorption of CH4, is considered to be the most slow partial step. The correlation of the carburization with the adsorption is supported by the relations: Thus can be regarded as Ea, the activation energy of the adsorption. Its value was determined at 109 kJ/mol being equivalent to 1.1 eV, which is characteristic for a chemisorption. Further it was established, that the rate of the decarburization according to equation (2) increases with decreasing temperature, i.e. the (apparent) activation energy proved to be negative. This is explained by the fact that before its rate-controlling desorption the CH4-molecule first of all must be formed step-by-step and by the assumption that for thermodynamical reasons the surface concentration of CH4 increases very much with decreasing temperature. The range of validity of the kinetic equations (1) and (2) can be limited to each other as follows:
  • – The kinetic law (1) is established especially at higher H2-pressures and at surfaces with low, but effective impurities. The impurities simultaneously result in a high decline of the reaction rate.
  • – The kinetic law (2) is valid especially at lower H2-pressures.
  相似文献   

10.
Equilibrium of Ce-Al-O or Nd-Al-O system in molten iron was studied by separately melting radioactive isotope 141Ce or 147Nd in an Al2O3 crucible filled with pure iron to form 141CeAlO3 or 147NdAlO3 around its inner wall. The content of dissolved Ce or Nd in iron was determined by means of electrolysis in anhydrous electrolyte and radioassay. The concentration of dissolved Al in iron was obtained by photometry and followed by calculation. Activity of oxygen in liquid iron was directly measured by solid electrolyte sensors made of ZrO2(MgO) tube. By extrapolation of data obtained, the temperature dependence of the equilibrium constant of RE-Al-O in molten iron, , or of interaction coefficient, may be described as:   相似文献   

11.
The equilibrium solubility of nitrogen in austenitic iron-chromium, iron-manganese, and iron-chromium-manganese alloys with mass up to 20 % Cr and 18 % Mn was measured in the temperature range 1273 to 1473 K. The following interaction parameters were obtained: (1) Describing the effect of chromium and/or manganese on the nitrogen solubility by the excess term , the present measurements correspond satisfactorily to those of Hertzmann and Jarl and of Zheng in the system Fe-Cr-N, but they differ somewhat from values calculated by means of parameters published by Frisk. For the system Fe-Mn-N the present measurements correspond to measurements by Grabke et al. and to values calculated with parameters published by Qiu. Using parameters deduced from the present measurements in the austenitic Fe-Cr-Mn-N system similar nitrogen solubilities were calculated as Zheng had measured, but small deviations were found between the analysis by Qiu and this investigation.  相似文献   

12.
Conventional thermochemical standard data are defined for dissolved elements i in iron. The standard partial enthalpy and entropy and in ideal dilute solution are described as simple temperature functions ai and bi are constants and denotes the partial molar heat capacity, which may be considered constant within a certain temperature range. From and further functions are derived, e.g. the conventional standard chemical potential and the modified Planck function βi. The constants ai, bi, are evaluated and compiled for α-, γ, δ-iron as well as for liquid iron, as far as experimental data are available. In addition to the standard data the first order interaction coefficients for elements dissolved in liquid iron at 1873 K have been revised and tabulated.  相似文献   

13.
The surface reaction kinetics have been investigated for the reaction CH4 (gas) = C (dissolved) + 2H2 (gas) on Fe and Fe-M foils (M = Mn, Cr, Co, Ni, Sn) at temperatures between 800 and 1000°C. The resistance relaxation method was applied in a flow apparatus. The following rate equation was observed for the rate of carbon uptake where is the carbon concentration and k and k′ are the rate constants for carburization and decarburization respectively. For Fe, Fe-10 Ni and Fe-10 Co the value of v = 3, for the alloys with > 20% Ni as well as for all Fe-Mn and Fe-Cr alloys the value v = 4 results from the measurements, which indicates differences in the rate determining step. With increasing Cr, Mn, Ni, Co content the rate constants k and k′ increase. The decrease of the equilibrium carbon concentration with increasing Ni content in Fe-Ni alloys is correlated to a fast increase of k′ and a slow increase of k with increasing Ni content. Beyond the minimum of at about 70 wt.% Ni both rate constants show a strong increase. By holding Ni at high carbon activities (aC > 0.7 at 1000°C) segregation of carbon induces a surface reconstruction which is characterized by formation of (111) planes and which reduces the reaction rates. The increase of the equilibrium carbon concentration in the systems Fe–Mn and Fe–Cr with increasing content of alloying element is correlated to a slow increase of k′ and a fast increase of k with increasing Mn or Cr content. Sn segregates to the surface and retards the reaction rate by blocking the reaction sites for the surface reaction, similar to the effects of P and S.  相似文献   

14.
To better understand the thermodynamic behaviour of chlorine in blast furnaces, CaO‐SiO2‐Al2O3 slags were brought into equilibrium with Ar + H2 + HCl + H2O gas mixtures at temperatures between 1673 K and 1798 K. The dissolution of chlorine into molten slags could be well interpreted through a reaction: (1/2) {CaO}slag + (HCl) = {Ca1/2Cl}slag + (1/2) (H2O). Conforming to this formula, a linear relation was observed between log (%CI) and log with an anticipated slope of 1/2.  相似文献   

15.
The activities of FexO in CaO + CaF2 + SiO2 + FexO quaternary slags were measured by means of solid-oxide galvanic cell. The FexO activities in the slags are influenced by CaF2 as well as SiO2. At constant FexO mole fractions, e.g., , at low SiO2 mole fractions i.e., , the substitution of CaF2 for CaO has an effect of raising the FexO activity. At higher SiO2 mole fractions, e.g., , however, such an effect becomes insignificant.  相似文献   

16.
Zusammenstellung von Schrifttumsangaben für die Änderung der freien Standardenthalpien der Reaktionen , Mo + O2 ? MoO2 und in Eisenschmelzen. Neubestimmung der Temperaturabhängigkeiten der Größen ΔGoCr2O3, ΔGoMoO2 und ΔGoO im Eisen bei Temperaturen zwischen 1460 bzw. 1530 und 1725 °C. Nachweis der Anwendbarkeit der neu ermittelten thermodynamischen Funktionen durch EMK-Parallelmessungen an ThO2 (Y2O3)- und ZrO2 (MgO)-Festelektrolytzellen mit Cr-Cr2O3- und Mo-MoO2-Referenzelektroden in Reineisenschmelzen bei 1600 °C. Ermittlung des Parameters pe′ der Elektronenteilleitfähigkeit für einen teilstabilisierten ZrO2-Festelektrolyten mit einem Stoffmengengehalt von 5% MgO.  相似文献   

17.
Based on the possible ability of strip casting to produce a (100)<0vw> fibre texture by directional solidification, experiments of rolling, annealing and magnetic measurement were performed on samples that were directionally solidified by other means. Samples with a final texture of strong (001) component were obtained in steels with 3 wt.% Si and 0.2 wt.% Al. A B50 value of 1.71T was obtained in a as‐cast ring specimen. Starting samples have columnar grains with a diameter of about 1mm diameter tilted about 9°, on the average, relative to a perfect <100>//ND. Cold rolling produced the expected rotated cube (001)<>. Further processing steps led to the final texture mentioned above. The paper presents the texture evolution along the processing steps.  相似文献   

18.
Untersuchung des Ansatzes auf seine Wirksamkeit zur Korrektur der Meßergebnisse. Erprobung an zahlreichen Werkzeugstählen und hochlegierten Stählen mit max. etwa 2% C, 1,4% Si, 1,7% Mn, 25% Cr, 25% Ni, 8% Mo, 3,5% V, 18% W, 5% Co, 0,3% Al, 0,5% Ti und 0,6% Cu. Fehlerabschätzung und Einsatz von Kleinrechnern zur schnellen Ermittlung des korrigierten Wertes.  相似文献   

19.
The oxidative dephosphorization of carbon-saturated Fe-Mn alloys was successfully demonstrated by measuring the phosphorus partition ratio between BaO-MnO, BaO-MnO-BaF2, and BaO-CaOsatd.-MnO fluxes and liquid Fe-Mn-Csatd. alloy between 1573 and 1673 K. The phosphorus partition ratio increases with increasing BaO content of the flux. The phosphate capacity of the BaO-MnO flux is as high as that of the BaO-BaF2 flux and is far larger than those of CaO-bearing fluxes. Addition of BaF2 to the BaO-MnO flux increases BaO solubility, which increases the phosphate capacity. The manganese partition ratios between the BaO-MnO flux and Fe-Mn-Csatd. alloy were approximately constant at 0.64, 0.33, and 0.23 at 1573, 1623, and 1673 K, respectively. The carbon content of the BaO-MnO flux was measured as functions of slag composition, temperature, and partial pressure of CO. A stable species of carbon in the BaO-MnO flux was found to be BaC2 experimentally and thermodynamically. The sulfide capacity of the BaO-MnO system at 1573 K has been shown to be far larger than any known flux systems and to be a few times larger than that for the BaO-BaF2 system. Formerly Graduate Student, Department of Metallurgy, The University of Tokyo  相似文献   

20.
The nitride capacities in CaO-TiO2-TiO1.5 slags, and nitrogen distribution ratio between these slags and liquid Cu (LN = (mass-% N)/[mass-% N]) were measured by a gas-slag-metal equilibration technique, using a Mo crucible in the temperature range of 1823 to 1923 K under controlled partial pressures of oxygen and nitrogen . The values for , (mass-% Ti3+)/(mass-% Ti4+) ratio, and solubility of TiN in CaO-TiO2-TiO1.5 slags were obtained as a function of slag composition (XCaO = 0.24 ~ 0.39) and temperature. Activity coefficients of TiN were evaluated from the values for activity coefficients of Ti in liquid Cu which were calculated from the results of TiN saturation experiments.  相似文献   

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