Thermodynamic study of the effect of calcium on removal of phosphorus from silicon by acid leaching treatment

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.

Equilibrium of calcium vapor with liquid iron and the interaction of third elements

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],

Evaluation of unified interaction parameter model parameters for calculating activities of ferromanganese alloys: Mn-Fe-C, Mn-Fe-Si, Mn-C-Si, and Mn-Fe-C-Si systems

Interaction parameters for Mn-based alloys were evaluated using both carbon solubility and activity data for species in binary and ternary manganese alloys. The parameters at 1400 °C are the following

Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

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),

Determination of gibbs energy of formation of Ni-B-O system by electromotive force measurement using solid electrolyte

The standard Gibbs energies of formation of Ni₃B, Ni₂B, o-Ni₄B₃(Ni_0.586B_0.414), m-Ni₄B₃(Ni_0.564B_0.436), NiB, and Ni₃B₂O₆ of the Ni-B-O system have been determined by measuring electromotive forces of galvanic cells using a Y₂O₃-stabilized ZrO₂ solid oxide electrolyte. The results are as follows:

Interdiffusion in the carbides of the Nb-C system

Interdiffusion coefficients in Nb₂C and NbC_1−x were measured using bulk diffusion couples in the temperature range from 1400 °C to 1700 °C. Marker experiments were used to show that carbon is the only component undergoing significant diffusion in both carbides. Carbon concentrations were measured by difference using electron probe microanalysis, and interdiffusion coefficients were taken from Boltzmann-Matano analyses of the resulting concentration profiles. This analysis clearly showed that, in NbC_1−x, interdiffusion coefficient varies with carbon concentration, and is expressed by

The Equilibrium Between Titanium Ions and Titanium Metal in NaCl-KCl Equimolar Molten Salt

The equilibrium between metallic titanium and titanium ions, 3Ti²⁺ ? 2Ti³⁺ + Ti, in NaCl-KCl equimolar molten salt was reevaluated. At a fixed temperature and an initial concentration of titanium chloride, the equilibrium was achieved by adding an excess amount of sponge titanium in assistant with bubbling of argon into the molten salt. The significance of this work is that the accurate concentrations of titanium ions have been obtained based on a reliable approach for taking samples. Furthermore, the equilibrium constant   $ {\text{K}}_{\text{C}} = (x_{{{\text{Ti}}^{{ 3 { + }}} }}^{\text{eql}} )^{3} /(x_{{{\text{Ti}}^{{ 2 { + }}} }}^{\text{eql}} )^{2} $ K C = ( x Ti 3 + eql ) 3 / ( x Ti 2 + eql ) 2 was calculated through the best-fitting method under the consideration of the TiOCl dissolution. Indeed, the final results have disclosed that the stable value of K_C could be achieved based on all modifications.     

Effects of Interfacial Lattice Mismatching on Wetting of Ni-Plated Steel by Magnesium

In this study, wetting has been characterized by measuring the contact angles of AZ92 Mg alloy on Ni-electroplated steel as a function of temperature. Reactions between molten Mg and Ni led to a contact angle of about 86 deg in the temperature range of 891 K to 1023 K (618 °C to 750 °C) (denoted as Mode I) and a dramatic decrease to about 46 deg in the temperature range of 1097 K to 1293 K (824 °C to 1020 °C) (denoted as Mode II). Scanning and transmission electron microscopy (SEM and TEM) indicated that AlNi + Mg₂Ni reaction products were produced between Mg and steel (Mg-AlNi-Mg₂Ni-Ni-Fe) in Mode I, and just AlNi between Mg and steel (Mg-AlNi-Fe) in Mode II. From high resolution TEM analysis, the measured interplanar mismatches for different formed interfaces in Modes I and II were \( 17{\kern 1pt} \;{\text{pct}}_{{\{ 10\overline 11\}_{\text{Mg}} //\{ 110\}_{\text{AlNi}} }} \)-\( 104.3\;{\text{pct}}_{{\{ 110\}_{\text{AlNi}} //\left\{ {10\overline{1}0} \right\}_{{{\text{Mg}}_{ 2} {\text{Ni}}}} }} \)-\( 114\,{\text{pct}}_{{\left\{ {0003} \right\}_{{{\text{Mg}}_{ 2} {\text{Ni}}}} //\{ 111\}_{\text{Ni}} }} \) and \( 18\,{\text{pct}}_{{\{ 10\overline 11\}_{\text{Mg}} //\{ 110\}_{\text{AlNi}} }} \)-\( 5\,{\text{pct}}_{{\left\{ {110} \right\}_{\text{AlNi}} //\{ 110\}_{\text{Fe}} }} \), respectively. An edge-to-edge crystallographic model analysis confirmed that Mg₂Ni produced larger lattice mismatching between interfaces with calculated minimum interplanar mismatches of \( 16.4\,{\text{pct}}_{{{\text{\{ 10}}\overline 1 1 {\text{\} }}_{\text{Mg}} / / {\text{\{ 110\} }}_{\text{AlNi}} }} \)-\( 108.3\,{\text{pct}}_{{{\text{\{ 110\} }}_{\text{AlNi}} / / {\text{\{ 10}}\overline 1 1 {\text{\} }}_{{{\text{Mg}}_{ 2} {\text{Ni}}}} }} \)-\( 17.2\,{\text{pct}}_{{{\text{\{ 10}}\overline 1 1 {\text{\} }}_{{{\text{Mg}}_{ 2} {\text{Ni}}}} / / {\text{\{ 100\} }}_{\text{Ni}} }} \) for Mode I and \( 16.4\,{\text{pct}}_{{{\text{\{ 10}}\overline1 1 {\text{\} }}_{\text{Mg}} / / {\text{\{ 110\} }}_{\text{AlNi}} }} \)-\( 0.6\,{\text{pct}}_{{{\text{\{ 111\} }}_{\text{AlNi}} / / {\text{\{ 111\} }}_{\text{Fe}} }} \) for Mode II. Therefore, it is suggested that the poor wettability in Mode I was caused by the existence of Mg₂Ni since AlNi was the immediate layer contacting molten Mg in both Modes I and II, and the presence of Mg₂Ni increases the interfacial strain energy of the system. This study has clearly demonstrated that the lattice mismatching at the interfaces between reaction product(s) and substrate, which are not in direct contact with the liquid, can greatly influence the wetting of the liquid.     

Diffusion of Au in the Intermetallic Compound Ti<Subscript>3</Subscript>Al

The Au diffusion in the Ti₃Al compound was investigated at six compositions from 25 to 35 at. pct Al by using the diffusion couples (Ti-X at. pct Al/Ti-X at. pct Al-2 at. pct Au; X = 25, 27, 29, 31, 32, and 35) at 1273 to 1423 K. The diffusion coefficients of Au in Ti₃Al ( D_\textAu^{\textTi₃ \textAl} ) \left( {D_{\text{Au}}^{{{\text{Ti}}_{3} {\text{Al}}}} } \right) are relatively close to those of Ti. The D_\textAu^{\textTi₃ \textAl} \texts {D}_{\text{Au}}^{{{\text{Ti}}_{3} {\text{Al}}}} {\text{s}} slightly increase with Al concentration within the same order of magnitude. The activation energies of Au diffusion, Q_\textAu^{\textTi₃ \textAl} \texts, Q_{\text{Au}}^{{{\text{Ti}}_{3} {\text{Al}}}} {\text{s}}, evaluated from the Arrhenius plots were relatively close to those of Ti diffusion, Q_\textTi^{\textTi₃ \textAl} \texts, Q_{\text{Ti}}^{{{\text{Ti}}_{3} {\text{Al}}}} {\text{s}}, rather than those of Al diffusion, Q_\textAl^{\textTi₃ \textAl} \texts; {Q}_{\text{Al}}^{{{\text{Ti}}_{3} {\text{Al}}}} {\text{s}}; therefore, it was suggested that Au atoms diffuse by the sublattice diffusion mechanism in which Au atoms substitute for Ti sites preferentially in Ti₃Al and diffuse by vacancy mechanism on Ti sublattice. The influence of the D0₁₉ ordered structure (hcp base) of Ti₃Al on diffusion of Au and other elements is discussed by comparing the diffusivities in Ti₃Al and α-Ti.     

Effect of Slag Composition on the Concentration of Al2O3 in the Inclusions in Si-Mn-killed Steel

The thermodynamic equilibria between CaO-Al₂O₃-SiO₂-CaF₂-MgO(-MnO) slag and Fe-1.5 mass pct Mn-0.5 mass pct Si-0.5 mass pct Cr melt was investigated at 1873 K (1600 °C) in order to understand the effect of slag composition on the concentration of Al₂O₃ in the inclusions in Si-Mn-killed steels. The composition of the inclusions were mainly equal to (mol pct MnO)/(mol pct SiO₂) = 0.8(±0.06) with Al₂O₃ content that was increased from about 10 to 40 mol pct by increasing the basicity of slag (CaO/SiO₂ ratio) from about 0.7 to 2.1. The concentration ratio of the inclusion components, \( {{X_{{{\text{Al}}_{2} {\text{O}}_{3} }} \cdot X_{\text{MnO}} } \mathord{\left/ {\vphantom {{X_{{{\text{Al}}_{2} {\text{O}}_{3} }} \cdot X_{\text{MnO}} } {X_{{{\text{SiO}}_{2} }} }}} \right. \kern-0pt} {X_{{{\text{SiO}}_{2} }} }} \) , and the activity ratio of the steel components, \( {{a_{\text{Al}}^{2} \cdot a_{\text{Mn}} \cdot a_{\text{O}}^{2} } \mathord{\left/ {\vphantom {{a_{\text{Al}}^{2} \cdot a_{\text{Mn}} \cdot a_{\text{O}}^{2} } {a_{\text{Si}} }}} \right. \kern-0pt} {a_{\text{Si}} }} \) , showed a good linear relationship on a logarithmic scale, indicating that the activity coefficient ratio of the inclusion components, \( {{\gamma_{{{\text{SiO}}_{2} }}^{i} } \mathord{\left/ {\vphantom {{\gamma_{{{\text{SiO}}_{2} }}^{i} } {\left( {\gamma_{{{\text{Al}}_{2} {\text{O}}_{3} }}^{i} \cdot \gamma_{\text{MnO}}^{i} } \right)}}} \right. \kern-0pt} {\left( {\gamma_{{{\text{Al}}_{2} {\text{O}}_{3} }}^{i} \cdot \gamma_{\text{MnO}}^{i} } \right)}} \) , was not significantly changed. From the slag-steel-inclusion multiphase equilibria, the concentration of Al₂O₃ in the inclusions was expressed as a linear function of the activity ratio of the slag components, \( {{a_{{{\text{Al}}_{2} {\text{O}}_{3} }}^{s} \cdot a_{\text{MnO}}^{s} } \mathord{\left/ {\vphantom {{a_{{{\text{Al}}_{2} {\text{O}}_{3} }}^{s} \cdot a_{\text{MnO}}^{s} } {a_{{{\text{SiO}}_{2} }}^{s} }}} \right. \kern-0pt} {a_{{{\text{SiO}}_{2} }}^{s} }} \) on a logarithmic scale. Consequently, a compositional window of the slag for obtaining inclusions with a low liquidus temperature in the Si-Mn-killed steel treated in an alumina ladle is recommended.     

Oxidation and Condensation of Zinc Fume From Zn-CO<Subscript>2</Subscript>-CO-H<Subscript>2</Subscript>O Streams Relevant to Steelmaking Off-Gas Systems

The objective of this research was to study the condensation of zinc vapor to metallic zinc and zinc oxide solid under varying environments to investigate the feasibility of in-process separation of zinc from steelmaking off-gas dusts. Water vapor content, temperature, degree of cooling, gas composition, and initial zinc partial pressure were varied to simulate the possible conditions that can occur within steelmaking off-gas systems, limited to Zn-CO₂-CO-H₂O gas compositions. The temperature of deposition and the effect of rapidly quenching the gas were specifically studied. A homogeneous nucleation model for applicable experiments was applied to the analysis of the experimental data. It was determined that under the experimental conditions, oxidation of zinc vapor by H₂O or CO₂ does not occur above 1108 K (835 °C) even for highly oxidizing streams (CO₂/CO = 40/7). Rate expressions that correlate CO₂ and H₂O oxidation rates to gas composition, partial pressure of water vapor, temperature, and zinc partial pressure were determined to be as follows:

$$ {\text{Rate}}\left( {\frac{\text{mol}}{{{\text{m}}^{2} {\text{s}}}}} \right) = 406 \exp \left( {\frac{{ - 50.2 \,{\text{kJ}}/{\text{mol}}}}{RT}} \right)\left( {p_{\text{Zn}} p_{{{\text{CO}}_{2} }} - p_{\text{CO}} /K_{{{\text{eq}},{\text{CO}}_{2} }} } \right)\,\frac{\text{mol}}{{{\text{m}}^{2} \times {\text{s}}}} $$

$$ {\text{Rate}}\left( {\frac{\text{mol}}{{{\text{m}}^{2} {\text{s}}}}} \right) = 32.9 \exp \left( {\frac{{ - 13.7\, {\text{kJ}}/{\text{mol}}}}{RT}} \right)\left( {p_{\text{Zn}} p_{{{\text{H}}_{2} {\text{O}}}} - p_{{{\text{H}}_{2} }} /K_{{{\text{eq}},{\text{H}}_{2} {\text{O}}}} } \right)\,\frac{\text{mol}}{{{\text{m}}^{2} \times {\text{s}}}} $$

It was proven that a rapid cooling rate (500 K/s) significantly increases the ratio of metallic zinc to zinc oxide as opposed to a slow cooling rate (250 K/s). SEM analysis found evidence of heterogeneous growth of ZnO as well as of homogeneous formation of metallic zinc. The homogeneous nucleation model fit well with experiments where only metallic zinc deposited. An expanded model with rates of oxidation by CO₂ and H₂O as shown was combined with the homogenous nucleation model and then compared with experimental data. The calculated results based on the model gave a reasonable fit to the measured data. For the conditions used in this study, the rate equations for the oxidation of zinc by carbon dioxide and water vapor as well as the homogeneous nucleation model of metallic zinc were applicable for various temperatures, zinc partial pressures, CO₂:CO ratios, and H₂O partial pressures.