Critical evaluation and thermodynamic modeling of the Fe–V–O (FeO–Fe2O3–VO–V2O3–VO2–V2O5) system

Critical evaluation and optimization of the Fe–V–O ternary oxide system was carried out based on all the available phase equilibria and thermodynamic property data at 1 atm total pressure. The Fe₃O₄–FeV₂O₄ spinel solid solution was described within the framework of Compound Energy Formalism considering the cation distribution between tetrahedral and octahedral sites. The wüstite phase, corundum phase, and VO₂ solid solution were described using a simple random mixing model. The Modified Quasichemical Model was used to describe liquid oxide solution in consideration of all multivalence states of Fe and V (Fe²⁺, Fe³⁺, V²⁺, V³⁺, V⁴⁺ and V⁵⁺). The variation of phase equilibria depending on the oxygen partial pressures and thermodynamic data in the system were well reproduced in the present study.     

Thermodynamic modeling of the Al–Bi,Al–Sb,Mg–Al–Bi and Mg–Al–Sb systems

All available thermodynamic and phase diagram data of the binary Al–Bi and Al–Sb systems and ternary Mg–Al–Bi and Mg–Al–Sb systems were critically evaluated, and all reliable data were used simultaneously to obtain the best set of the model parameters for each ternary system. The Modified Quasichemical Model used for the liquid solution shows a high predictive capacity for the ternary systems. The ternary liquid miscibility gaps in the Mg–Al–Bi and Mg–Al–Sb systems resulting from the ordering behaviour of the liquid solutions can be well reproduced with one additional ternary parameter. Using the optimized model parameters, the experimentally unexplored portions of the Mg–Al–Bi and Mg–Al–Sb ternary phase diagrams were more reasonably predicted. All calculations were performed using the FactSage thermochemical software package.     

Thermodynamic assessment of the Si–Zn,Mn–Si,Mg–Si–Zn and Mg–Mn–Si systems

The binary Si–Zn and Mn–Si systems have been critically evaluated based upon available phase equilibrium and thermodynamic data, and optimized model parameters have been obtained giving the Gibbs energies of all phases as functions of temperature and composition. The liquid solution has been modeled with the Modified Quasichemical Model (MQM) to account for the short-range-ordering. The results have been combined with those of our previous optimizations of the Mg–Si, Mg–Zn and Mg–Mn systems to predict the phase diagrams of the Mg–Si–Zn and Mg–Mn–Si systems. The predictions have been compared with available data.     

Thermodynamic optimization of the ZnO–FeO–Fe2O3–SiO2 system

Liquidus phase equilibria experimental data of the present authors for the ZnO–“Fe₂O₃”–SiO₂ system in air, ZnO–“FeO”–SiO₂ in equilibrium with metallic Fe, and ZnO–“FeO”–SiO₂–minor Cu₂O at p(O₂) ~10⁻⁷ … 10⁻⁸ atm (obtained as a part the research on the multicomponent PbO–ZnO–FeO–Fe₂O₃–Cu₂O–CaO–SiO₂ system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the ZnO–FeO–Fe₂O₃–SiO₂ system for the whole range of compositions, p(O₂) between ~10⁻¹³ to 1 atm, and temperature range corresponding to liquid slag existence (1150–1700 °C). The modified quasichemical model is used for the liquid slag phase. From these optimized model parameters, the ternary phase diagrams are back calculated. The model based on the present set of parameters is in a good agreement with previous and new experimental data, and can be used for predictions of the ZnO–FeO–Fe₂O₃–SiO₂ phase equilibria over wide ranges of p(O₂), compositions and temperatures, as well as multicomponent systems.     

Thermodynamic optimization of the PbO–FeO–Fe2O3–SiO2 system

Liquidus phase equilibrium data of the present authors for the PbO–FeO–Fe₂O₃ system at various oxygen potentials, PbO–“Fe₂O₃”–SiO₂ system in air, and PbO–“FeO”–SiO₂ in equilibrium with metallic Pb, combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the PbO–FeO–Fe₂O₃–SiO₂ system. The modified quasichemical model is used for the liquid slag phase. For the liquid phase, the PbO–FeO, PbO–Fe₂O₃, PbO–FeO–Fe₂O₃, PbO–FeO–SiO₂ and PbO–Fe₂O₃–SiO₂ parameters are optimized in the present study. From these model parameters, the optimized ternary phase diagram is back calculated. Present set of parameters describe previous and new experimental data well, and can be used for predictions of the PbO–FeO–Fe₂O₃–SiO₂ phase equilibria over wide ranges of oxygen partial pressured, compositions and temperatures, as well as multicomponent systems.     

Modelling the giant,Zn–Pb–Ag Century deposit,Queensland, Australia

This paper presents a combination of geometric reconstructions of the Century Zn–Pb–Ag deposit, and finite-difference modelling of coupled deformation and fluid flow. Our intention is to demonstrate that these computer-based applications represent a new approach in testing ore genesis models. We use a “visiometric” approach, utilising GoCad 3D structural and property modelling. Computer visualisation is applied to reveal metal zonations, fault distributions and timing, stratigraphic influence on zoning, and the nature and extent of metal redistribution during basin evolution and deformation. We also examine possible links between fluid flow, deformation, and mass transfer using the numerical code FLAC3D. Numerical modelling results suggest that subsurface fluid flow during basin inversion is compartmentalised, being focussed within more permeable fault zones, thus accounting for the secondary redistribution of base metals identified using the 3D reconstructions. However, the results do not explain the broad metal zonation observed. Both the spatial and numerical models suggest that Century is syngenetic, with further diagenesis and deformation producing 1–100 m-scale (re)mobilisation.     

Thermodynamic assessment of the Ca–Zn,Sr–Zn,Y–Zn and Ce–Zn systems

Published experimental thermodynamic and phase diagram data for the Ca–Zn, Sr–Zn, Y–Zn and Ce–Zn systems have been critically evaluated to provide assessed thermodynamic parameters for the different phases of the systems. The parameters allow all thermodynamic properties and phase boundaries for each system to be calculated within reasonable error limits. Because a strong compound-forming tendency and pronounced minimum in the enthalpy of mixing curve is observed for the liquid phase of all the systems, the Modified Quasichemical Model (MQM) in the pair approximation has been used throughout the assessment work to treat short-range ordering in the liquid.     

Thermodynamic assessment of the CaO–Cu2O–FeO–Fe2O3 system

Thermodynamic assessment of the CaO–Cu₂O–FeO–Fe₂O₃ system is presented. Effects of temperature and P(O₂) on the phase equilibria involving slag, solubility of copper and the Fe³⁺/Fe²⁺ ratio in slag have been modeled using available experimental data. Subsolidus phase equilibria and concentration of iron in liquid copper were evaluated as well. Different ways of representing phase equilibria in a quaternary system are illustrated. The slag model, [Ca²⁺, Cu⁺, Fe²⁺, Fe³⁺][O²⁻], was developed using the Modified Quasichemical Model (MQM). Liquid metal phase is modeled using the MQM, but as a separate solution, (Cu^I, Fe^II, O^II). Spinel phase is modeled using the Compound Energy Formalism (CEF) and takes into account the solubility of copper and calcium. A thermodynamic database produced in the present study can be used for predictions in pyrometallurgical processing of copper involving calcium ferrite slags. The database is internally consistent with the binary and ternary sub-systems published earlier, as well as with higher-order systems. It works in the environment of FactSage, ChemApp, ChemSheet and SimuSage software packages.     

Experimental study and thermodynamic optimization of the ZnO–FeO–Fe2O3–CaO–SiO2 system

Liquidus phase equilibrium experimental data from the present study for the ZnO-“Fe₂O₃”-CaO-SiO₂ system in air, combined with phase equilibria and thermodynamic data from the literature on the ZnO-“Fe₂O₃”-CaO system in air and ZnO-“FeO”-CaO-SiO₂ system in equilibrium with metallic Fe, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases in the ZnO–FeO–Fe₂O₃–CaO–SiO₂ system. The modified quasichemical model is used for the liquid slag phase; spinel (Fe,Zn,Ca)^tetr (Fe,Zn,Ca,Va)^oct₂O₄, melilite Ca₂(Fe²⁺,Fe³⁺,Zn)(Fe³⁺,Si)₂O₇ and olivine (Fe,Zn,Ca)^I(Fe,Zn,Ca)^IISiO₄ are described with compound energy formalism; lime and wustite (monoxide) (Ca,Fe,Zn)O, zincite (Zn,Fe,Ca)O_1+x, calcium-zinc ferrites Ca₂Fe₂O₅-“CaZnO₂” and CaFe₄O₇-“ZnFe₄O₇”, α- and α′-dicalcium silicate (Ca,Fe,Zn)₂SiO₄ and tricalcium silicate (Ca,Fe,Zn)₃SiO₅ and silicoferrite of calcium (SFC) Ca₉Fe₄₆SiO₈₀–Ca₁₂Fe₄₀Si₄O₈₀ are described within Bragg-Williams formalism; for other phases, previous assessments have been adopted. The phase diagrams are back calculated with the optimized model parameters. Present study is a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe₂O₃-“Cu₂O”-CaO-SiO₂ system.     

First-principles study of binary special quasirandom structures for the Al–Cu,Al–Si,Cu–Si,and Mg–Si systems

Based on special quasirandom structures (SQS’s) and first-principles calculations, enthalpies of mixing have been predicted for four binary fcc solid solutions in the Al–Cu, Al–Si, Cu–Si, and Mg–Si systems at nine compositions (x=0.0625$x=0.0625$, 0.125, 0.1875, 0.25, 0.5, 0.75, 0.8125, 0.875, 0.9375, where x$x$ is the mole fraction of A atoms in the A–B binary system). The present results are compared with previous first-principles calculations and thermodynamic modeling results available in the literature. In order to provide insight into the understanding of mixing behavior for these solid solutions, the spatial charge density distributions in these binary solid solutions are also analyzed. The results obtained herein indicate that the SQS model can be used to estimate the thermodynamic properties of solid solutions, especially for metastable phases, the thermodynamic qualities of which are rarely measured.     

美国Y2K补丁97%打完

美国政府近日发表声明,他们已经完成97%的关键计算机系统的 Y2K 补救工作,花费了83.4亿美元。美国军方声称其导弹系统已经确定不受千年虫影响,随时可以应战。     

O_2性能改进后提高30%

SGI公司宣布通过对O_2工作站性能的进一步改进,在不额外增加任何成本的基础上,O_2工作站能为用户提供了更加出色的图形处理功能与友好的交互界面,性能提高了30％。 提高O_2工作站图形性能,主要是优化O_2IRIX6.3操作系统中OpenGL库。娱乐业、制造业及科研机构的生产人员与专业技     

DB2首季同比增长110%

尽管几家大的数据库公司在最近几个季度以来其数据库产品的销售额有所下降,但IBM的决策者4月底宣布该公司的数据库产品销售旺盛。IBM首季在基于Unix和Windows NT上的数据库软件销售情况较上一年同期增长了110％,具有较高利润率的、基于大型机的数据库软件的销售额平均每年以11％的速度增长。