Volume and Surface Properties of a Bismuth-Containing Separating Nickel Melt

The influence of a bismuth impurity on the properties of solid and liquid alloys in the concentration range that obeys Henry’s law is considered. The structural and physicochemical properties, specifically, the density and the surface tension, of real melts are studied on relatively pure metals. The changes in the properties of the melts are estimated from changes in the temperature dependences of the density and the surface tension upon heating and cooling and in the concentration dependences of these parameters at a constant temperature. These dependences exhibit a correlation between the volume and surface properties of the melts: the density and the surface tension increase or decrease simultaneously. The introduction of bismuth in the nickel melt is accompanied by the appearance of a relatively strong compression effect (i.e., a decrease in the melt volume). At a certain bismuth content in the melt, the compression effect weakens because of the appearance of an excess phase or its associates and melt separation.     

Effect of Exogenous Zirconia Nanophases on the Structural Properties of the Sulfur- and Tin-Containing Nickel Melts

The surface tension and the density of the nickel melts with introduced ZrO₂ nanoparticles are studied by the sessile drop method using a digital camera and computer processing of images. The revealed differently directed effects of nanoparticles on the surface tension in the Ni–Sn and Ni–S systems points to a change in the structure of the melt–gas surface layer. The nanoparticles are shown to affect the adsorption of surfactants, and the surface layer is likely to consist of adsorbed Ni + (ZrO₂–surfactant) ensembles. The ZrO₂ content in a metal is determined using the technique of separate determination of the zirconium content dissolved in a metal and zirconium in the form of ZrO₂. It was found that, at 0.10 wt % ZrO₂ initially present in a metal, 0.021–0.031 wt % ZrO₂ are retained in samples; that is, about 70 rel % ZrO₂ are removed to the interface in the form of ensembles. Auger spectroscopy analysis of the Ni–Sn–ZrO₂ surface film detected 5–10 rel % Zr in the surface layer.     

Thermodynamic Properties of Mn-C Melts

Carbon solubility in Mn-Fe melts（xMn=0.161-0.706,xFe=0.034-0.633）was measured experimentally at various temperatures.By thermodynamic derivation and calculation,the relationship between activity coefficient of carbon in infinite dilute solution of manganese in Mn-C system and temperature was obtained.Using Gibbs-Duhem relationship,the experimental results of this study,and experimental data reported in references,the relationship between other thermodynamic properties in Mn-C system and temperature were obtained by thermodynamic derivation and calculation.     

Thermodynamic Properties of Cu-Ce-O and Cu-RE-O Melts

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Thermodynamic Properties of Fe-C-N and Fe-C-B-N Melts

The saturated solubility of carbon and nitrogen in Fe-C-N and Fe-C-B-N melts was measured experimentally at 1 485℃ to obtain the activity interaction coefficients between components in these melts. A new method was used to treat experimental results. Using thermodynamic derivation and calculation, some important interac- tion coefficients between components in these melts were obtained.     

锰铁熔体中磷和锰的热力学性质

通过１４００℃下Ｆｅ－Ｍｎ－Ｃ－Ｐ系中碳的溶解平衡实验，测定了该熔体中碳的溶解度，应用热力学理论计算出，，，并提出了适用于锰铁熔体中磷和锰的活度系数计算式     

Thermodynamic Properties of Carbon and Manganese in Mn-C and Mn-Fe-C Melts

Carbon solubility in Mn Fe melts （xMn =0. 083-0. 706, XFe =0. 034-0. 715） was measured experimentally at various temperatures. By thermodynamic derivation and calculation, the relationship between activity coefficient of carbon in infinite dilute solution of manganese in Mn-C system and temperature was obtained. Using Gibbs-Duhem relationship, the experimental results of this study, and experimental data obtained by strict thermodynamic derivation and calculation in references, the relationships between other thermodynamic properties （εCC, εCCC, εCFe, εCCFe, and εCFeFe） in Mn-Fe-C system and temperature were obtained.     

高镍锌白铜的性能研究

采用水平连铸－拉拔－轧制生产工艺锌白铜异材，对高镍锌白铜的金相组织，机械性能及退火工艺进行了研究。研究表明α单相高镍锌白铜具有优良的机械性能，适宜冷热加工，退火温度为７００－７５０℃，颜色为银白色。该材料完全能满足高档眼镜用异形材料的要求。     

Enthalpy of Mixing and Excess Volume of Binary Metallic Melts of Eutectic Systems

The enthalpies of mixing H and excess volumes V were analyzed in alloy formation from binary metallic eutectic systems. Three types of systems can be distinguished: I with H > 0, V > 0; II with H > 0, V 0; III with H < 0, V 0. The hypothesis is discussed that another yet unstudied group IV exists in which H < 0, V < 0.     

含钡二元合金熔体热力学性质的计算

根据Miedema二元合金生成热模型，结合相关热力学数据，对Si-Ca二元合金熔体在1623K时的组元活度进行了计算，计算结果与实测结果吻合较好。并进一步对Ba-Si、Ba-Al和Ba-Ca3种二元含钡合金熔体的生成热△H及1873K时的过剩熵S^E、过剩自由能G^E以及不同温度下各组元的活度等热力学性质进行了计算。结果表明：3种合金的△H、S^E和G^E均为负值，且S^E绝对值的最大值为4．424J／mol，可以近似认为3种合金熔体的S^E为零；Ba-Si和Ba-Al合金熔体的活度相对于理想溶液存在较大负偏差，而Ba-Ca合金熔体的活度与理想溶液偏差较小。     

钨镍(W-Ni)的焊接性能及工艺

异种金属的有效连接在高新技术领域具有实际意义,采用电阻点焊方法焊接稀有金属钨片和镍丝.用SEM,HRTEM表征焊接接头的组织形貌,用拉伸试验机测定焊接件的抗剪切力.采用如下焊接工艺:第一阶段:预压力是100 N,使钨镍良好接触;第二阶段:保持预压力不变,施以预热电流1.1KA,400 ms,然后再施以焊接电流1.7KA...     

Modeling of Exchange Interactions in Melts Formed During Joint Smelting of Oxidized Nickel Ores and Pyrrhotite Concentrates

Metallurgist - An original methodology based on the use of experimental values of the conditional equilibrium constants in metallurgical calculations was employed to perform a theoretical modeling...     

Influence of Atomic and Molecular Hydrogen in Silumins Melts on Their Mechanical Properties

Metallurgist - We study the influence of gas porosity caused by the presence of dissolved hydrogen on the mechanical properties of Al–Si alloys. The results are obtained by testing cast...     

The Electrochemical Formation of Ni-Tb Intermetallic Compounds on a Nickel Electrode in the LiCl-KCl Eutectic Melts

The work presents an electrochemical study on the formation of Ni-Tb intermetallic compounds in the LiCl-KCl-TbCl₃ melts on tungsten and nickel electrodes at 773 K (500 °C) by electrochemical techniques. For a tungsten electrode, cyclic voltammetry and square-wave voltammetry showed that the electrochemical reduction of Tb(III) proceeded in a one-step process involving three electrons at ?2.06 V (vs Ag/AgCl). For a nickel electrode, the reduction potential of Tb(III)/Tb was observed at more positive values than those on W electrode by cyclic voltammetry, due to the formation of Ni-Tb intermetallic compounds. Square-wave voltammetry and open-circuit chronopotentiometry put into evidence the formation of intermetallic compounds at around ?1.27, ?1.63, and ?1.88 V, respectively. Three alloy samples were obtained by potentiostatic electrolysis on a Ni electrode at various potentials and analyzed by X-ray diffraction, scanning electron micrograph, and energy-dispersive spectrometry. The analysis results confirmed the formation of Ni₁₇Tb₂, Ni₅Tb, and Ni₂Tb alloy compounds.     

MLCC内电极用超细镍粉表面改性研究

利用还原法对超细镍粉进行表面改性，形成Ni—BO体系，从而提高镍粉的抗氧化性能。文章着重研究了NaBH4的用量、反应温度、PH值对超细镍粉抗氧化性的影响。最终确定了最佳条件。利用热重分析法DTA—TGA对镍粉的抗氧化性进行检测。研究表明，改性后镍粉的抗氧化性得到明显的改善。     

纯镍钝化膜的电化学性能

为了搞清镍的钝化行为,本文用极化曲线法及交流阻抗技术,通过对纯镍在中性H₃BO₃-Na₂B₄O₇溶液及添加了K₃Fe(CN)₆/K₄Fe(CN)₆氧化-还原系溶液中的极化行为及交流阻抗特性的研究,讨论了钝化膜的电模型和电极反应。     

Determination of the Oxygen Content in the Complexly Alloyed Nickel Melts during Vacuum Induction Melting Using Oxygen Probes

A procedure providing an ultralow oxygen content during the melting of complexly alloyed nickel superalloys is developed. The procedure uses special oxygen probes and makes it possible to control the oxygen concentrateon in a melt rapidly. The procedure is approved on a VIM150 setup for the melting of commercial nickel superalloys. The procedure developed for the determination of the oxygen content on VIM12 and VIM150 setups can also be used for other alloys, including newly developed ones.     

Preparation and Properties of Iron Powder Plated with Nickel and Cobalt

The magnetic properties (magnetic induction and coercive force) of iron powder coated with nickel and cobalt as a result of chemical deposition from hypophosphite electrolytes are studied. Thermogravimetry, differential thermal and x-ray phase analyses are used to study in detail the kinetics and mechanism of high-temperature oxidation in air (up to 1200°C) for the original and coated powders. The phase composition of oxide films on specimens annealed at all temperatures of the DTA-curve peaks is determined. The possibility of increasing the high-temperature oxidation resistance of iron powder coated with nickel or cobalt is demonstrated.