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Materials like metallic iron and its alloys are essential to daily living and industrial production. The benefits of using electrolysis technology to prepare iron and its alloys are great efficiency, controllability, and environmental protection. This study focuses on the feasibility of the electrochemical method for the direct preparation of metallic iron and Si–Fe alloys in iron ores with high fluoride content. The electrochemical behavior of Fe(II) and Fe(III) in molten SiO2–CaO–CaF2 slag on tungsten electrodes was investigated by using cyclic voltammetry and square wave voltammetry methods. It was determined that the reduction of Fe(II) ions follows a one-step two-electron transfer process: Fe(II) + 2e− → Fe(0). The reduction of Fe(III) involves a two-step electron transfer process: Fe(III) + e− → Fe(II) and Fe(II) + 2e− → Fe(0), respectively. The Fe(II)/Fe(0) process is an irreversible reaction controlled by diffusion. The diffusion coefficient of Fe(II) is DFe(II) = 1.5 × 10−6 cm2 s−1. The cathodic deposits of iron were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The findings indicate that the production of Fe2Si alloy through electrolysis is more favorable when Fe(II) is present in the slag, while the production of metallic iron is more favorable when Fe(III) is present in the slag. This work provides a basis for the electrochemical direct preparation of Fe–Si alloy and metallic iron in high fluorine iron ore. [ABSTRACT FROM AUTHOR]

Copper-based composites with different quality scores for NbC particle reinforcement were prepared by spark plasma sintering. The microstructure of the copper-based composites with different NbC contents was studied, and the influence of NbC content on the density, electrical conductivity and hardness of the copper-based composites was investigated. The results showed that the electrical conductivity of the Cu-4 wt% NbC composite material after spark plasma sintering was 70.4% IACS (IACS is the percentage of the ratio of the conductivity of the sample to a certain standard value. The annealed copper wire with a density of 8.89 g cm−3, a length of 1 m, a weight of 1 g and a resistance of 0.15328 Ohm is used as this certain standard value), and the hardness was 63.4 HV. The strengthening mechanisms of NbC in copper-based composites were dispersion strengthening and fine crystal strengthening. During the spark plasma sintering process, the Zener pinning of NbC particles slowed grain boundary migration, which effectively prevented the pure copper grains from growing and thus enhanced the pure copper. The proportion of NbC in the raw powder was changed to adjust the proportion of fine crystals, and then the mechanical properties of the material were adjusted. Additionally, NbC caused a preferred orientation of pure copper and reduced some of the stress in the material. [ABSTRACT FROM AUTHOR]

Silicon has been applied in many fields, such as high-purity semiconductors, high-temperature resistant materials, optical fiber connection materials, organosilicon compounds, and alloys. In this work, silicon was extracted from the Bayan Obo tailing by high-temperature electrolysis. The reduction process of Si(IV) and the effect of CaF2 content on the reduction process were studied in the SiO2–CaO–CaF2 melt. The Si(IV) ions in the SiO2–CaO system with 10 wt pct CaF2 were reduced by a one-step four-electrons transfer process. In the SiO2–CaO melt with 15, 20, and 30 wt pct CaF2, the reduction process of Si(IV) was a two-step two-electrons transfer process: Si(IV) + 2e → Si(II) and Si(II) + 2e → Si(0). The reduction process of Si(IV) to Si(II) was reversible and was controlled by diffusion. The diffusion coefficient was 1.52 × 10−8 cm2 s−1. Si and WSi2 were prepared under a current density of − 0.55 A cm−2 at 1738 K. It was found that the WSi2 alloys were formed because of the alloying of Si(IV) and W. [ABSTRACT FROM AUTHOR]

A population-based metaheuristic algorithm that takes its cues from the foraging strategy of sparrows is called the sparrow search algorithm (SSA). While SSA is competitive when compared to other algorithms, it nevertheless has a propensity to carry out imbalanced exploitation and exploration and find the local optimum. Therefore, the modified adaptive sparrow search algorithm (MASSA), an SSA modification, is created to address these problems. To increase population variety, the MASSA uses a chaotic reverse learning technique. Second, to balance the exploitation and exploration capacities, a dynamic adaptive weight is added. In the end, an adaptive spiral search technique improves algorithm performance. Among 23 classical test functions, of which 13 are multidimensional and the other 10 are fixed dimensional, the best chaotic operator is found. It is proven that MASSA is superior. Simulation studies demonstrate that the MASSA described in this study is superior to previous algorithms in terms of stability, convergence speed, and convergence accuracy. Finally, a sample robot path planning problem is resolved using MASSA, and the experimental outcomes confirmed the viability and usefulness of MASSA. [ABSTRACT FROM AUTHOR]

Energy storage devices and conversion systems have attracted more and more attention with the rapid development of clean energy. Iron oxide is widely used as electrode materials and electrocatalysts because of its abundant resource, low cost, and superior electrical and catalytic properties. Doping sulfur in iron oxide is an effective method to improve electrochemical and photocatalytic performance. The common synthesis method of sulfur-doped iron oxide is a three-step method of co-precipitation, hydrothermal, and calcination. This method has to be performed under high pressure and high temperature, so it needs to consume more energy. In this work, the electrochemical synthesis of sulfur-doped iron oxide was investigated under atmospheric pressure and temperature in the aqueous ferrous sulfate solution that was used as the precursors of sulfur, iron and oxygen. The influences of solution pH on the electrochemical synthesis process and the composition and morphology of deposits were investigated by the analyses of electrochemical reaction and SEM–EDS of deposits. It was found that the oxygen content in the deposit decreased as the pH value of the solution increased. There were three electrochemical reduction processes in sequence from positive to negative potential, followed by the underpotential deposition of iron on the platinum electrode, hydrogen evolution and sulfur doping. The sheet sulfur-doped iron oxide was successfully prepared by electrodeposition under a potential more negative than −1.70 V vs MSE. The kinetics of the electrochemical reaction of iron ions on the platinum electrode was investigated. The reduction process was a quasi-reversible process controlled by diffusion. The heterogeneous charge transfer rate constant ks and the diffusion coefficient D were obtained. [ABSTRACT FROM AUTHOR]

The phase relations in the CaO-SiO2-Ce2O3 system under the reducing atmosphere at 1873 K were determined by the conventional equilibrium and quenching method combined with scanning electron microscopy-electron probe microanalysis (SEM-EPMA) and X-ray diffraction (XRD) measurements on the quenched samples. Based on these analyses, a large part of the isothermal phase diagram was constructed. Furthermore, the thermodynamic activities of Ce2O3 in the melts at 1873 K were measured by the chemical equilibrium method. Using the measured activity data, an empirical formula to estimate the activity coefficient of Ce2O3 was proposed based on the regular solution model. It was found that, for the melts with the same Ce2O3 contents, the thermodynamic activities of Ce2O3 increase gradually with the rise of basicity (the ratio of CaO to SiO2) of the melts. This implies that, from the thermodynamic point of view, the increase of basicity is favorable to the enrichment and precipitation of Ce-containing mineral phases. [ABSTRACT FROM AUTHOR]

The present work aimed to measure the thermodynamic data of manganese in Cu-Mn melts over a broad manganese concentration range, using the equilibrium among the liquid copper/MnO/CO-CO gas mixture in the temperature range from 1673 K to 1873 K (1400 °C to 1600 °C). Darken's quadratic formalism was introduced to correlate the activity coefficient of manganese in copper to composition, and the excess molar Gibbs energy change of mixing of Cu-Mn melts was described satisfactorily by Redlich-Kister type polynomial. [ABSTRACT FROM AUTHOR]

It is a useful way to stabilize the elements of heavy metal in the glass-ceramics with the form of ions due to the environmental pollution of heavy metal, such as Cr. The glass-ceramics of excellent combination properties were prepared, and the effect of stabilizing Cr-containing stainless steel slag with different concentrations of nitric acid leaching test were investigated. It was found that the major crystalline phase was diopside or anorthite with or without the amount stainless steel slag. Moreover, the continuous refinement of grains exhibited with the increase of amount of stainless steel slag. The results indicated that the excellent physical and mechanical properties, including density (2.9 g/cm3), hardness (729.27HV0.3), bending strength (222.9 MPa), and the solid solution of Cr in excess of 0.00057% for the glass-ceramics were related to the change of microstructure and phase structure. There showed the potential for reusing and detoxifying stainless steel slag. [ABSTRACT FROM AUTHOR]