Ignition of nickel in environments containing oxygen and chlorine

The mixed oxidation of nickel in gases containing both oxygen and chlorine has been investigated using the techniques of thermogravimetric analysis and examination of the corrosion products by scanning electron microscopy. Two regimes of corrosion behavior have been detected: one in which a protective oxide film is present and the rate of corrosion is controlled by the transport of the volatile products of the reaction between the gas phase and the oxide, and one in which the protective film is penetrated and corrosion occurs rapidly enough to result in the ignition of the specimen. The oxide corrosion products on the specimens after corrosion have characteristic morphologies, with the products of volatilization type corrosion consisting of large grains and the products of ignition type attack consisting of fine spherical particles. Ignition is a serious hazard in environments containing 0.25 pct or more Cl₂ and 4 pct or more O₂ by volume at temperatures between 1000 K and 1100 K, but is not produced by exposures at higher temperatures. A model based on the stability of the protective film in steady state corrosion is presented which can be used to predict the transition from volatilization to ignition type attack.     

Ignition of nickel in environments containing oxygen and chlorine

Metallurgical and Materials Transactions A - The mixed oxidation of nickel in gases containing both oxygen and chlorine has been investigated using the techniques of thermogravimetric analysis and...     

Thermodynamics of oxygen solutions in nickel melts containing aluminum and titanium

Thermodynamic analysis of oxygen solutions in nickel melt shows that, as aluminum and titanium are added to the melt, the solubility of oxygen decreases. However, after reaching 0.205% Al and 0.565% Ti, the oxygen concentration in the melt begins to rise with increase in the Al and Ti content. The minimum oxygen concentrations in the reduction of nickel melt by aluminum (1.44 × 10^–4% O) and titanium (2.98 × 10^–4% O) are determined. On that basis, we may propose the optimal approach to alloying nickel melts with aluminum and titanium. First, the melt is reduced by adding sufficient aluminum to minimize the oxygen concentration in the melt (~0.2% Al). Then the oxide formed is removed, so as to prevent repeated oxidation of the melt. Finally, the melt is alloyed with aluminum and titanium to obtain the required alloy composition.     

High temperature corrosion of superalloys in an environment containing both oxygen and chlorine

The corrosion behavior of a series of commercial superalloys in flowing argon-20 pct oxygen-2 pct chlorine at 900 °C has been investigated using thermogravimetric analysis and examination of the condensed corrosion products using X-ray diffraction analysis and optical and scanning electron microscopy. Most of the alloys exhibited decreases in mass due to formation of volatile chloride or oxychloride corrosion products. An exception is the alloy 214 which showed little change in mass due to the formation of a protective alumina scale. Alloys which are high in refractory metals, notably alloys S and C-276, snowed the highest rates of attack. In addition to the metal wastage, several of the alloys were subject to internal attack in the region near the corroded surface. Formerly Graduate Student, Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago     

The effect of chlorine on the kinetics of oxidation of cobalt in environments containing 0.5 atmosphere of oxygen between 900 K and 1200 K

The corrosion of cobalt metal in gas mixtures containing argon, chlorine, and 0.5 atmosphere of oxygen has been studied by measuring the kinetics of the reaction using thermogravimetric techniques and by examination of the corrosion products using scanning electron microscopy. The corrosion products include both oxides and chlorides. The formation of volatile cobalt chloride plays a critical role in the corrosion process by attacking and penetrating the condensed oxide scale. At 1200 K, the Tedmon equation describes the kinetics of the corrosion process. At lower temperatures the corrosion behavior is more complex, and under some conditions the formation of a porous, nonprotective oxide scale can lead to rapid consumption of the metal. Formerly Graduate Research Assistant     

Transformations of non-metallic inclusions formed during interaction in a cupreous melt containing nickel and oxygen

The values of thermodynamic parameters, which characterize thermodynamic features for interaction processes in the Cu-Ni-O system under the conditions of cupreous-melt and condensed-oxide-phase coexistence, were obtained. The solubility surface of components in metal is constructed for the Cu-Ni-O system at temperatures of 1100–1300°C. The structure and form of oxide inclusions formed during interaction in a cupreous melt containing nickel and oxygen were experimentally investigated.     

Kinetics of solution of hydrogen in liquid iron,nickel, and copper containing dissolved oxygen and sulfur

An investigation of the effect of surface active oxygen and sulfur on the rate of hydrogen solution in inductively stirred liquid iron, nickel, and copper was made using a modified constant-volume Sieverts’ method. The overall and initial rates of hydrogen solution in liquid iron and nickel were found to decrease with increasing oxygen content in concentration ranges found in the commercial refining of these metals. The results were consistent with a change in the rate controlling step from mass transport of hydrogen atoms in the metal phase to mixed control of a surface chemical reaction and a diffusion controlled process in the melt. For liquid copper the overall rate of hydrogen solution decreased with increasing oxygen content, but the initial rate could not be determined. It was believed that condensation of water vapor and melt surface turbulence interfered with measurement of the initial rate of hydrogen solution in liquid copper. The addition of sulfur to liquid iron, nickel, and copper lowered the overall rate of hydrogen solution, but the effect was not as pronounced as that for oxygen. Formerly Graduate Student, The University of Michigan, is Research Engineer, Noranda Research Center, Pointe Claire, Quebec, Canada     

X射线荧光光谱法测定镍电解液中的镍、氯、硫酸根

本文利用低功率X射线荧光分析技术(XRF)对电解镍溶液样品进行了研究,重点探讨了影响镍电解液中Ni²⁺、Cl^-、SO₄^2-同时测量的因素,优化了实验条件。实验表明,镍的质量浓度（ρ）在35～110 g/L、氯离子的质量浓度（ρ）在30～90 g/L、硫酸根离子的质量浓度（ρ）在55～160 g/L范围内,待测元素质量浓度与其荧光强度存在着良好的线性关系。将本方法用于镍电解液实际样品分析,测得结果与其它化学分析方法结果相符合,相对标准偏差（RSD,n=11）为0.3%～0.4%。
     

浅析高冰镍氯气浸出制取镍电解初液

氯气浸出工艺是当前世界上先进的高镍锍精炼工艺之一,在镍的回收率、生产率、产品质量及工作环境等方面具有较突出的优势.氯化湿法冶金由于具有高反应速率、高浸出率、以及灵活的金属提取工艺组合等优点,成为一项重要的湿法冶金新技术,以往制备镍电解初液的工艺都采用硫酸常压选择性浸出-加压浸出工艺,这样的工艺具有浸出效率低、工艺设备复杂、流程长、作业强度高、生产成本高等缺点.为了解决这些不利的因素,现在学者都在探索氯化浸出工艺替代硫酸选择性浸出工艺.本文就氯气浸出生产镍电解初液的工艺原理、试验过程、试验结果及其优点进行了充分的阐述.     

The diffusion and solubility of oxygen in solid nickel

Solid-state electrochemical measurements using various experimental procedures were made with the double cell: $$ Ni + NiO|ZrO_2 + Y_2 O_3 |Ni + \underline O |ZrO_2 + Y_2 O_3 |Ni + NiO $$ to determine the diffusivity and thermodynamic functions of oxygen dissolved in solid nickel. Non-steady state diffusion of oxygen in the specimen was caused by applying a preselected potential between the reference and specimen electrodes and was monitored by measuring time-dependent potentials and/or currents. The following results were obtained for the diffusivity of oxygen and the solubility of oxygen in nickel in equilibrium with NiO: $$D{\text{ = 4}}{\text{.9 }} \times {\text{ 10}}^{{\text{ - 2}}} {\text{ exp}}\left( {{\text{ - }}\frac{{{\text{164 kJ/mole}}}}{{{\text{R}}T}}} \right){\text{cm}}^{\text{2}} /{\text{sec (850 to 1400 }}{}^{\text{o}}{\text{C)}}$$ $$C_{\text{O}}^s {\text{ = 8}}{\text{.3 exp}}\left( { - \frac{{55{\text{kJ/mole}}}}{{{\text{R}}T}}} \right){\text{at}}{\text{. pct (800 to 1000 }}{}^{\text{o}}{\text{C)}}$$ The thermodynamic and transport behaviors of oxygen in solid nickel were fairly well described by a simple quasi-regular model and an interstitial diffusion model, respectively.     

Dissolution kinetics of chalcopyrite containing pyrite in water saturated with chlorine

In this work the dissolution kinetics of chalcopyrite in water saturated with chlorine have been investigated using particle size, reaction temperature and gas flow rate as parameters. It has been found that the dissolution rate decreased with an increase in particle size and reaction temperature, but increased with an increase in gas flow rate. The mechanism by which the dissolution proceeds has been deduced. It has been concluded that the dissolution is controlled by diffusion through the product layer. The activation energy was calculated as 9.06 kJ mol⁻¹.     

Sulfide stress cracking susceptibility of nickel containing steels

A systematic evaluation of the sulfide-stress cracking (SSC) behavior of five steels with nickel contents ranging from 0 to 3 pct was conducted in an acidified chloride solution saturated with H₂S at room temperature (NACE solution). All of the steels were low-alloy, structural, or pressure vessel steels that are heat treatable to high strength levels with high toughness. All of the steels were heat treated to yield strength of approximately 690 MPa (100 ksi) and evaluated by identical test methods. The relative cracking susceptibility of the steels was determined from threshold stresses in constant-load tension tests and threshold stress intensities shown by precracked double-cantilever-beam specimens. Tempering treatment was a decisive factor in SSC susceptibility of low-nickel steels. When double tempered, low-Ni steels with greater than 1 pct Ni can be equivalent in SSC resistance to nominally nickel-free 4130 steel.     

Defect clusters in neutron-irradiated vanadium containing oxygen

Single crystal samples of high-purity vanadium containing 95, 300, and 500 wt ppm oxygen were irradiated at 95°C in the Ames Laboratory Research Reactor to a dose of 1.4 x 10¹⁹ neutrons/cm² (E > 1 MeV). The density and size distribution of radiation-produced defect clusters were analyzed by transmission electron microscopy in as-irradiated and post-irradiation-annealed material. The defect cluster density was observed to increase with increasing oxygen concentration and the average defect cluster size to decrease. Upon post-irradiation annealing the density decreased and the average size increased, but higher annealing temperatures were required for higher oxygen material. The results are discussed in terms of the nucleation of defect clusters at oxygen atoms and small oxygen-atom aggregates. The increased stability against annealing of higher oxygen vanadium is believed to be due to the greater segregation of oxygen at the defect clusters.     

Remelting of scrap containing tungsten and nickel in the electric arc furnace

Remelting of the metallic scrap containing tungsten and nickel and thermodynamic properties of slag containing tungsten oxide are discussed. Tungsten and nickel in the metallic scrap have to be separated before the scrap may be used for melting of some steels (for example, high speed steel). To separate tungsten and nickel, such scrap (waste drills) was remelted in the 25 t electric arc furnace under oxidizing conditions. Tungsten was oxidised and transferred to the slag phase, while nickel remained in the metal. Further, the slag containing tungsten oxide was used in the melting of high speed steel. Metal containing nickel was utilized in the constructional steel production. Technology of the scrap remelting was developed on the basis of thermodynamic analysis of slag containing tungsten oxide and tungsten slag-metal partition. It was found that the coefficient of tungsten distribution between iron and basic CaO-SiO₂-Fe_tO-WO₃ slag increases with increasing slag basicity. In the industrial oxidising heats a slag of high basicity was used, it secured 94% tungsten extraction from scrap to the slag.     

Defect clusters in neutron-irradiated vanadium containing oxygen

Single crystal samples of high-purity vanadium containing 95, 300, and 500 wt ppm oxygen were irradiated at 95°C in the Ames Laboratory Research Reactor to a dose of 1.4 x 10¹⁹ neutrons/cm² (E > 1 MeV). The density and size distribution of radiation-produced defect clusters were analyzed by transmission electron microscopy in as-irradiated and post-irradiation-annealed material. The defect cluster density was observed to increase with increasing oxygen concentration and the average defect cluster size to decrease. Upon post-irradiation annealing the density decreased and the average size increased, but higher annealing temperatures were required for higher oxygen material. The results are discussed in terms of the nucleation of defect clusters at oxygen atoms and small oxygen-atom aggregates. The increased stability against annealing of higher oxygen vanadium is believed to be due to the greater segregation of oxygen at the defect clusters. The work was performed at Ames Laboratory under contract with Energy Research and Development Administration.     

The thermodynamics of ternary palladium-based solid solutions containing nickel and hydrogen

The solubility of hydrogen in Pd-Ni-H ternary solutions in equilibrium with H gas at atmospheric pressure has been measured in the temperature range 625–1250 K and in Pd-Ni “binary solvents” containing up to 80 at.% of Ni. Concomitant elastic measurements have provided data which enable the partial thermodynamic functions of the H-atoms, deduced from the solubility measurements, to be converted so as to refer to a hypothetical Pd-Ni lattice of constant specific volume. The resulting “volume corrected” functions have been discussed in terms of the cell model for ternary solutions and have been shown to vary with temperature and Ni-concentration in a manner in accord with this mode. The usual linear form of cell interaction energy spectrum has been modified by including supplemental contributions to the cell interaction energy which occur when substitutional solute atoms occupy adjacent sites on the f.c.c. Pd-Ni lattice.