Vacuum-dynamic disintegration of melts. III. Experimental examination of the operation of a vacuum-dynamic atomization unit

Conclusions A vacuum-dynamic unit operates in a stable manner in the atomization of metals with melting points ranging from 230 to 1200C. The key control parameters of the device are the blast pressure and the gap between the nozzles. To obtain finer powders, the former should be increased and the latter decreased.Translated from Poroshkovaya Metallurgiya, No. 10(274), pp. 63–65, October, 1985.     

Centrifugal pneumatic disintegration of melts

Translated from Poroshkovaya Metallurgiya, No. 3(327), pp. 4–8, March, 1990.     

Centrifugal pneumatic disintegration of melts. II. Production of tin-base powders and their main properties

Translated from Poroshkovaya Metallurgiya, No. 5(329), pp. 8–11, May, 1990.     

Centrifugal hydraulic method of melt disintegratio. II. Effect of the physicochemical properties of metallic melts on the particle size of powders

Conclusions Lowering the surface tension of the melt leads to a decrease in the mean powder particle size. By adding a small amount (0.5%) of a surface-active agent to the melt, it is possible to substantially increase the yield of fine powder fractions. Lowering the viscosity of the melt, e.g., by superheating it by 10–20% above its melting point, enables the mean powder particle size to be decreased by a factor of 1.5–2. Powders of smaller particle size can be produced by using atomization injectors made of materials exhibiting lower adhesional activity toward melts. CHA of melts of lower density results, other things being equal, in the formation of finer powders.Translated from Poroshkovaya Metallurgiya, No. 9(321), pp. 10–14, September, 1989.     

Dynamics of the process of metal disintegration by compressed gas

Summary A technique is described for calculating the principal atomization-process parameters — gas velocity and temperature — enabling powder of the required particle size to be produced. The results obtained are presented in the form of a nomogram constructed on the basis of the following dimensionless numbers: Fedorov Number Fe, Reynolds Number Re, and blow-by coefficient k characterizing the conditions of heat exchange between gas and metal. The method of application of the nomogram is described.Translated from Poroshkovaya Metallurgiya, No. 4 (64), pp. 6–9, April, 1968.     

Modeling the dependence of alumina solubility on temperature and melt composition in cryolite-based melts

The solubility of alumina in NaF-AlF₃ melts was calculated and modeled thermodynamically for the temperature range of 1240 to 1300 K (967 °C to 1027 °C). The solute complexes of alumina in the cryolite melts were identified to be Na₂Al₂OF₆ (acidic solute), Na₂Al₂O₂F₄ (neutral solute), and Na₄Al₂O₂F₆ (basic solute). The assumption that the oxygen-free solute species in solution were Na₃AlF₆ and NaAlF₄ was supported by the modeling results. The equilibrium constants for the formation reactions of the solutes were calculated and the corresponding ΔG _f ⁰ values were evaluated as a function of temperature. The interaction derivatives (∂ ln a _NaF/∂x _add, ∂ ln a _NaF/∂x _add, and ∂ ln a _AlF3/∂x _add) for small additions of LiF, CaF₂, and MgF₂ to the NaF-AlF₃-Al₂O₃ ternary system were also estimated as a function of temperature and melt composition.     

Thermodynamics of titanium-based melts: II. Oxygen in liquid titanium

A method for the conversion of the thermodynamic characteristics of iron-based melts into those of titanium-based melts is used to calculate the change in the Gibbs free energy when oxygen dissolves in liquid titanium and when titanium is deoxidized by deoxidizing elements. It is established that beryllium is the most rational deoxidizer for structural, high-temperature, and functional titanium alloys and calcium is the most rational deoxidizer for foundry alloys. Free oxygen or volatile monoxides from liquid titanium cannot pass to a gaseous medium in vacuum, since it needs an unattainably low residual pressure.     

Hydrodynamics of gas stirred melts: Part II. Axisymmetric flows

A predictive model of gas stirred melt is presented. Based on the differential approach and following a review of previous models, the importance of natural convection or buoyancy driven phenomena is underscored. Predicted flow patterns are shown to be consistent with laboratory and pilot scale experiments, and with the macroscopic plume model in Part I of this paper.     

Influence of melt carbon and sulfur on the wetting of solid graphite by Fe-C-S melts

The interfacial phenomena between carbonaceous materials such as graphite, coke, coal, and char and Fe-C-S melts are important due to the extensive use of these materials in iron processing furnaces. However, the understanding of the interfacial phenomena between these kinds of carbonaceous materials and molten iron alloys is far from complete. In this study, graphite was selected as the solid carbonaceous material because its atomic structure has been well established. The sessile drop method was adopted in this investigation to measure the contact angle between solid graphite and molten iron and to study the interfacial phenomena. The influence of carbon and sulfur content in Fe-C-S melts on the wettability of solid graphite has been investigated at 1600 °C. The melt carbon content was in the range of 0.13 to 2.24 wt pct, and the melt sulfur content was in the range of 0.05 to 0.37 wt pct. X-ray energy-dispersive spectrometer (EDS) analysis was conducted on an HITACHI S-4500 scanning electron microscope to detect composition distribution at the interfacial region. It was found that contact of solid graphite with Fe-C-S melts will result in a nonequilibrium reactive wetting. It involved carbon transfer from the solid to the liquid and iron transfer from the liquid to the solid. The Fe-C-S melts exhibited relatively poor wetting when the reactions were absent. The mass transfer between solid graphite and Fe-C-S melts was observed to strongly enhance the wetting phenomena. It is proposed that the decrease of system free energy corresponding to the mass transfer reactions strongly influences the formation of the interface region and results in the progressive spreading of the wetting line. The composition and thickness of the graphite/iron interfacial layer was dependent on the intensity of mass transfer across the interface. The resulting change in the interfacial energy γ _ls is a strong function of mass transfer, and it varies in accordance with time of contact. The influence of carbon content on the wetting phenomena could only be seen at in the initial stages, whereas the influence of sulfur on the wettability was found when the system approached equilibrium. Therefore, the interfacial tension in its equilibrium condition at the graphite/Fe-C-S melt interface was determined only by the extent of sulfur adsorption at this interface.     

A new Big Five: Fundamental principles for an integrative science of personality.

Despite impressive advances in recent years with respect to theory and research, personality psychology has yet to articulate clearly a comprehensive framework for understanding the whole person. In an effort to achieve that aim, the current article draws on the most promising empirical and theoretical trends in personality psychology today to articulate 5 big principles for an integrative science of the whole person. Personality is conceived as (a) an individual's unique variation on the general evolutionary design for human nature, expressed as a developing pattern of (b) dispositional traits, (c) characteristic adaptations, and (d) self-defining life narratives, complexly and differentially situated (e) in culture and social context. The 5 principles suggest a framework for integrating the Big Five model of personality traits with those self-defining features of psychological individuality constructed in response to situated social tasks and the human need to make meaning in culture. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AOD过程基本的数学模拟

针对AOD(氩氧脱碳)过程提出了一个新的仿真模型,模型考虑了局部的变化,但仍然保证了计算的高效性。一个新的思路就是把AOD转炉作为流股区的活塞流反应器和熔池与表面熔渣的连续搅拌池反应器的组合来模拟。这种方法比之以前的模型有很多优点。首先,它提供了考虑气泡在流股中上升过程局部变化条件的有效方法。因为变量更少,相对于计算流体动力学(CFD)模型,这种构造使其能够非常高效地运算。模型的验证也更容易,因为它具有可被试验确定的特征。将模型与两种不同的试验(高Cr和低Cr钢种)情况进行了对比,结果表明,模型对脱碳和Cr行为的预测很好。利用模型输出结果可以获得主导机制的信息,更为重要的是何种元素主要参与氧的反应。模型给出了不同成分的元素如何在喷嘴附近区域首先发生氧化,之后又在熔渣上浮过程中被部分还原。模型同时包含了对氮行为的模拟,因此可以系统地用于优化脱氮。     

Fundamental relation between the main parameters of the thermally activated transport phenomena in complex oxide melts

The relation between the activation energy and the preexponential factor in the Arrhenius equation that describes the viscosity and electrical conductivity of oxide (slag) melts is systematically analyzed over wide composition and temperature ranges for the first time. When deriving this relation, we do not use any model concepts and assumptions concerning the structure of slag melts or the character of electric charge transfer in them. The fundamental applicability of the Meyer-Neldel rule for this relation is shown and grounded. The application of this algorithm in practice can give information on the structure of experimental data, nonobvious correlations, and possible relations of a higher order and can quantitatively predict the behavior of parameters, including the range outside experimentally determined data.     

Interaction of the oxyfluoride melts of Ca,Si, Mg,Al, and Na with steels: II. Chromium-nickel-containing melts

The interaction of a mixture containing Ca, Si, Mg, Al, and Na oxides and fluorides with an ironbased chromium-nickel-containing melt at 1600°C and p _Ar = 0.1 MPa is studied. The equilibrium concentrations of the components in the slag are determined at a holding time of 500 s. The chromate capacity of this melt is calculated, and this value is related to the composition using the optical basicity.