Smelting Research Articles

Magnetic properties of quenched binary and ternary quasicrystal approximants

The magnetic properties of binary Gd-Cd and ternary Gd-Au-Ge crystals obtained from the newly introduced low-melt peritectic formation (LMPF) synthesis method were investigated. This method consists of a rapid quenching of the metallic melt followed by an annealing treatment at a relevant temperature. In the first system, both quasicrystal (QC) and approximant crystal (AC) phases can be stabilized, whereas only the AC phase is obtainable in the pseudo-binary Gd-(Au-Ge) system. The magnetic properties of the crystals obtained from LMPF for each system are compared to those of larger single grain crystals obtained from the self-flux (SF) method.

Activation and development of direct plasma spark sintering and this method after the synthesis of combustion of ceramic-metal compositions through different mixtures of metal melts and/or intermetallic compounds

The article shows the effect of different mixtures melts of metals and/or intermetallic compounds with various oxide, non-oxide additives, obtained solid solutions of metallic phases during spark plasma sintering, spark plasma sintering after combustion synthesis on the phase composition, micrstructure, grains sizes of crystalline phases, relative density, linear shrinkage, microstructural featres of boundary layers, paths of microcracks, physical-mechanical properties, values of standart erors of properties of samples. Synthesized powders of h-BN, B4C, NiTi, NiZr are characterisized by high intensity of crystallization of h-BN, B4C, NiTi, NiZr. Sintered by spark plasma method c-ZrO2, c-BC2N at pressing loadings 35 MPa and 1400 oC, 5 GPa and 2327 oC in boron melt show evoluted crystalli-zation of c-ZrO2, с-BC2N phases, respectively, crystalline, uniform and dense microstructures. Obtained by combustion synthesis powder shows multi-phase composition with various crystallization of phases. Sintered by direct spark plasma method samples show evoluted mullitization, crystallization of c-ZrO2, solid solutions of metallic phases, but in the samples, obtained by spark plasma method in different sintering conditions after combustion synthesis are visible crystalline, multi-intensive phases. The samples show crystalline, multi-uniform and multi-dense microstructures, variously dispersed grains of crystalline phases. Sintered samples are differ by the relative density, linear shrikage, density, uniformity, width, path of boundary layers and propagating microcracks across these boundary layers, the resistance to the cracking, values of physical-mechanical properties, values of standart errors of properties of samples.

Вивчення змочування SnO2—In2O3-кераміки розплавами срібло—мідь

To improve the wetting of oxide ceramic with metals in addition to traditional dopands (Ti, Zr, Nb, etc.), which have a high chemical affinity to solid phase atoms, alternative active additions can also be used. In particular, it relates to non-metallic electronegative elements VIa—VIIa groups of the periodic system (O, S, Se, F, Cl, Br), which have a high affinity to electron. Such additives are able to reduce free surface energy at the liquid/gas and liquid/solid interfaces and in such a way improve the wetting. The SnO2—In2O3 system is the most optimal material for the layers of the so-called TCO (Transparent Conductive Oxide). Since the cost of metal indium and its compounds continues to grow and new technologies are actively developing, there is a need to find alternative TCO that would have less In2O3 content. That is why systems containing SnO2, doped by relatively small amounts of In2O3 were explored. Ag—Cu based fillers is often used to joint oxide materials. In this case, there is a significant effect of the additives of the third component on the activity of oxygen in liquid metal, which causes an increase in oxygen content directly in the melt. Specially synthesized high-dense ceramics based on SnO2, which was received by adding 5, 10, 20 or 40% (mass.) of In2O3 with subsequent sintering, were used for wetting experiments. The experimental data indicate that in vacuum and air copper, added to the silver melt, significantly improves wetting on all types of the studied ceramic substrates, as well as the wetting is improved with increasing of the In2O3 content in the substrate. A dense transition layer of about 10 μm, which contains a large amount of copper, is formed on the interfacial border. A similar phenomenon was observed at the inter-phase boundary of other oxide materials. The improvement of wetting is explained by an increase in the solubility of oxygen in the melt, which acts as an adhesive-active element, with the addition of copper and increased electronegativity of the substrate with increasing content of In2O3. Keywords: tin dioxide, indium oxide, semiconductor, wetting, contact interaction, metal melt.

Оксид галію — перспективний мультифункціональний матеріал четвертого покоління (огляд)

This work is devoted to the analysis and systematization of the main information on the properties of gallium oxide and materials based on it and their practical application, as well as the prospects for further research of the specified actual oxide material. A review of literature data concerns general properties and structure of gallium oxide Ga2O3, various methods to produce Ga2O3 thin films, nanostructures, bulk crystals, powders, the application of gallium oxide in various fields of science and technology, including semiconductor field, electronic engineering, optoelectronics, the creation of composite transparent materials, etc. In the last thirty years or so, thanks to the progress in growing large-volume, high-quality gallium oxide crystals, this material with an ultra-wide band gap and a high critical breakdown field has gained significant application in the manufacture of the latest power electronics and high-voltage electronic devices. Important experimental studies, in particular, in terms of developing methods of metallization, joining similar materials, connecting electrical contacts, for example, by soldering, require the study of the wetting of these oxide materials by metal melts and the contact interaction at the interphase boundaries. Data on surface phenomena, in particular the wetting of gallium oxide by metals, are practically absent in the literature, and this requires further additional research. Keywords: gallium oxide, physical properties, semiconductor, power electronics, optoelectronics, transparent composite materials.

Formation of B2 Phase and its Phase Stability in Equiatomic Al-Cu-Fe-Ni-Ti High Entropy Alloy

In the present investigation, we have synthesized a single-phase high-entropy alloy in Al-Cu-Fe-Ni-Ti system by melting of the individual metals using a radiofrequency induction furnace under an argon environment. The as-synthesized alloy shows the formation of a B2-type ordered phase with a lattice parameter of 0.289nm. The mechanical stability of this single phase high-entropy alloy was investigated under high-energy ball milling. The milling was performed at a speed of 400rpm for 10, 20, and 40h under a hexane medium with a ball-to-powder ratio of 40:1. The formation of nano crystallites (~ 10nm sizes) body centered cubic (BCC) phase (disordered B2) has been observed after 40h of ball milling, which has been confirmed by X-ray diffraction and transmission electron microscopic investigation. The equiatomic Al-Cu-Fe-Ni-Ti high entropy alloy structure is observed to be quite stable during mechanical milling up to 40h; only grain refinements and lattice strain accumulation were observed with milling time.

Investigation of enhanced PCM heat sink design under extreme thermal conditions for high-heat-generating electronic devices

In this study, a novel enhanced phase change material (PCM) heat sink design is proposed to improve energy efficiency and maintain quiet operation under extreme thermal conditions for high-heat-generating electronic devices. To overcome the thermal conductivity and heat transfer limitations of the PCM heat sinks, fins, metal foams, and nanoparticles were integrated. A simulation model for the PCM heat sink was developed based on experiments. The thermal performances of different PCM heat sinks were comprehensively evaluated and compared through an in-depth analysis of their thermal behaviors. Consequently, at the heat flux of 20 kW·m−2, a proposed nano-enhanced PCM heat sink with fins and metal foams reduces the surface temperature of high-heat-generating electronic devices by 40.0 K during pre-heating process and maintains a minimum temperature of 54.47°C, decreasing the temperature by 41.4 K during melting process compared to the PCM heat sink without thermal conductivity enhancers. Furthermore, the proposed PCM heat sink exhibited the longest critical duration, approximately 26 times longer than that of a PCM heat sink without thermal conductivity enhancers. Additionally, within the critical temperature range, employing a PCM with a suitable melting temperature and metal foam parameters is advantageous for the thermal management of high-heat-generating electronic devices.

Змочування ZnO-кераміки сплавами системи срібло—олово у вакуумі

ZnO is interesting as a promising material for use in various industries; in these applications there it is a need for metallization of ZnO-based materials, as well as their joining. For these purposes the using of liquid metal fillers is effective. Despite this, there are only a few single works that investigate issues related to the wetting and adhesion of metallic melts on the surface of zinc oxide or materials based on it. Therefore, the wetting of zinc oxide was investigated by Ag—Sn melts. intered ceramics made of pure ZnO without additions with porosity of 15%, silver and tin high purity were studied. Silver-tin alloys were prepared by previous melting in a vacuum. The wetting experiments were performed by the sessile drop method in vacuum. Addition of tin to silver can very significantly improve the wetting of the ZnO melt; there is a clear concentration dependence. The smallest of the contact angle is 57°. For the con¬centration of tin 5% at., when wetting has not yet been reached, a transition layer is observed between ceramics and metal. It is noticeable that lines, both between the ZnO substrate and the transition layer, and between the transitional layer and the frozen drop, are very uneven. Therefore, it can be concluded that the transition layer was not appeared due to adsorption, but formed as a result of the interaction of Ag—5Sn with ZnO, in particular uneven dissolution of the components of the substrate, possibly with the formation of a non-stoichiometric zinc oxide. In the case of tin concentration 10% (at.), when the melt wet the substrate, there is a zone containing two phases, dark and light (metal) in the ceramics under the drop. This two-phase area is obviously formed as a result of the impregnation of the melt in the pores in ceramic.Therefore, increasing the concentration of tin in Ag—Sn melts significantly improves the wetting of ZnO-ceramic by these systems, but the formation of developed transitional layers, as well as intensive impregnation of the melt deep into the ceramics complicates the use of these alloys for brazing or metallization of materials based on ZnO. Keywords: zinc oxide, wetting with metals, contact interaction, microstructure, transition layer

Documenting weld pool behavior differences in variable-gap laser self-melting and wire-filling welding of titanium alloys

In large-scale welding processes involving complex geometries, variations in gap dimensions and the transition of filler wire form distinctive molten pool flow behaviors, significantly affecting weld formation and quality. This paper investigates the differences in the laser self-melting and wire-filling welding pool behavior of titanium alloy with variable gaps through both simulation and experimentation. An innovative three-dimensional transient heat-flow coupling model is developed to simulate laser welding with variable gap structures, incorporating the dynamics of the welding wire-filling process. The different laser welding modes and the filling process under the variable gap structure were numerically simulated. The results indicate that the maximum flow rate of the laser self-melting pool remains stable in proximity to the keyhole, reaching a maximum of approximately 2.491 m/s, with molten metal entering through the area surrounding the keyhole. As the gap size gradually increases to 0.2 mm during the laser self-fusion welding stage, keyhole instability becomes more pronounced. In transitioning from laser self-fusion to wire-filling welding, the welding wire behavior can be divided into three stages. The molten metal at the end of the welding wire is transferred to the liquid melt pool through a liquid metal bridge. The flow rate of this bridge initially rises before gradually decreasing, reaching a maximum flow rate of 1.606 m/s. Notably, the welding wire lags approximately 0.6 mm behind the laser's focal point, with the narrowest width of the liquid bridge measuring about 0.89 mm. Based on the simulation results and considering the melting transition time of the welding wire, the initiation time for the welding wire has been further adjusted to the first 10 ms when the gap threshold reaches 0.2 mm. Experimental verification confirms the successful laser welding of a 2 mm variable gap structure thin plate. This study elucidates the melt pool flow, keyhole fluctuations, and metal transition behaviors during the laser welding process, contributing to a deeper understanding of the complex heat and mass transfer dynamics inherent in variable gap structure laser self-melting and wire-filling welding. Ultimately, these insights aim to enhance the application of laser welding in adaptive welding for large structural components.

Production of corundum boats and crucibles used for metal melting and material analysis by casting method

Production of corundum boats and crucibles used for metal melting and material analysis by casting method

Electrochemical Ironmaking for Green Steel: Turning Low-Grade Ore into High-Purity Iron

The production of steel accounts for approximately 7% of global carbon dioxide emissions, the majority of which is produced during the conversion of iron ore to iron metal (“ironmaking”). Conventional ironmaking predominantly utilizes blast furnaces which melt iron ore with coal and other minerals to produce crude steel. The effort to decarbonize is pressuring high emissions processes, like ironmaking, to transition to low-carbon alternatives. To achieve this goal, Electra has developed an acidic electrolysis-hydrometallurgical ironmaking process (Figure 1) that operates at low temperatures (~ 60C)(1). Contemporary solutions geared towards reducing emissions associated with the blast furnace ironmaking route involve combining reformed natural gas in a ‘direct reduced iron’ reactor (NG-DRI) to reduce iron ore to metallic iron. The NG-DRI path only moderately reduces carbon emissions relative to the blast furnace, about 35%. The next generation DRI technology instead utilizes hydrogen as the reductant gas (H2-DRI), which has the potential to significantly reduce emissions as long as the hydrogen is produced via electrolysis using renewable electricity sources. However, a major drawback to the DRI ironmaking process is that it cannot process impurities present in lower-grade ores, unlike the blast furnace approach which can removal impurities through “slag”, a byproduct of smelting that contains a mixture of metal oxides. Thus, DRI methods must either use high-grade ores (> 67% iron oxide), perform upstream beneficiation of low-grade ores, or add an additional downstream smelting step to remove impurities via slag. The latter two approaches incur significant cost, CO2 emissions, and waste. The diminishing availability of high-grade ores preferred by blast furnaces and required by DRI methods represents a significant challenge associated with these routes. A recent report by the International Iron and Metallics Association expects shortages in high-grade ore by the early 2030s(2). As the world supply of high-grade ore dwindles, new technologies are required to tap into lower-grade and, ideally, already mined waste feedstock. Electra’s ironmaking technology is capable of dissolving a range of iron ore grades in acid and extracting iron metal in a manner most similar to conventional copper or zinc electrowinning at around 60C(1). By dissolving iron ore in solution, traditional hydrometallurgical separations processes such as solids precipitation routes or solvent extraction can be employed to remove the principal impurities (Al2O3, SiO2, and P) present in low-grade ores. If removed with enough selectivity, these byproducts can also be valorized, further reducing the auxiliary carbon footprint of mining new materials. Electra’s impurity removal process is critical to electrodeposition of high-purity iron from leached ore solution. This presentation will focus on Electra’s electrowinning process and detail the impact of common iron ore impurities on the quality of electrodeposited iron. The presence of Al3+ and PO4 3- in plating catholyte, specifically, results in incorporation of these elements into the deposited iron via precipitation. These elements are particularly detrimental for steel production in the downstream electric arc furnaces. Reducing Al3+ and PO4 3- content to below ≈ 1 mM in solution eliminates impurity incorporation and results in iron purity of ≈ 99% as measured by LECO combustion analysis and acid digested ICP-OES. Other common ore impurities (Mg, Na, Mn) are ‘bystanders’ and do not negatively impact iron deposition, permitting build-up in the catholyte and eventual removal via a bleed stream. (1) Pham, et al. (2022) 2-Step Iron Conversion System. US Patent Office No. US11767604B2. (2) International Iron Metallics Association. www.metallics.org/faq.html (Accessed Feb 2024). Figure 1. Schematic that identifies the primary electrochemical and hydrometallurgical processing steps in Electra’s ironmaking technology. Figure 1

A note on the direction of core solidification in asteroids, the iron melting curve, and phase equilibria parameterizations

The accuracy of the pressure/temperature/composition parameterization of Buono and Walker (2011) to describe the liquidus of iron and the Fe-FeS system is examined. In the pressure range critical for asteroidal core crystallization (0- ∼2 GPa), the model predicts a shape for the iron melting curve (initially negatively sloped, and turning over near 0.7 GPa) that is inconsistent with previous experimental observations, thermodynamic constraints, and millennia of empirical metallurgical observations. Dodds et al. (2025) recently used this model to derive notable conclusions about the behavior of the solidifying cores of asteroids: the robustness of their conclusions is assessed. Two basic caveat emptor guidelines for employing parameterizations of phase equilibria data are suggested: (1) ensure that the model's fit is consistent with simple thermodynamic expectations; and (2) verify that the data used to formulate the model provide adequate coverage in the region of interest.

Is the mechanism of "fast sound" the same in liquids with long-range interactions and disparate mass metallic alloys?

We present abinitio simulations of a large system of 2400 particles of molten NaCl to investigate the behavior of collective mode dispersion beyond the hydrodynamic regime. In particular, we aim to explain the unusually strong increase in the apparent speed of sound with wave number, which significantly exceeds the typical positive sound dispersion of 10%-25% observed in simple liquids. We compare dispersions of "bare" acoustic and optic modes in NaCl with abinitio simulations of other ionic melts such as CuCl and LiBr, metallic liquid alloys such as Pb44Bi56 and Li4Tl, and the regular Lennard-Jones KrAr liquid simulated by classical molecular dynamics. Analytical expressions for the "bare" acoustic and optic branches of collective excitations help us to identify the impact of the high-frequency optic branch on the emergence of "fast sound" in binary melts. Our findings show that in ionic melts, the high-frequency speed of sound is much larger than in the simple Lennard-Jones liquids and metallic melts, leading to an observed strong viscoelastic increase in the apparent speed of sound-more than double its adiabatic value.

A consistent, volume preserving, and adaptive mesh refinement-based framework for modeling non-isothermal gas–liquid–solid flows with phase change

This work expands on our recently introduced low Mach enthalpy method (Thirumalaisamy and Bhalla 2023) for simulating the melting and solidification of a phase change material (PCM) alongside (or without) an ambient gas phase. The method captures PCM’s volume change (shrinkage or expansion) by accounting for density change-induced flows. We present several improvements to the original work. First, we introduce consistent time integration schemes for the mass, momentum, and enthalpy equations, which enhance the method stability. Demonstrating the effectiveness of this scheme, we show that a system free of external forces and heat sources can conserve its initial mass, momentum, enthalpy, and phase composition. This allows the system to transition from a non-isothermal, non-equilibrium, phase-changing state to an isothermal, equilibrium state without exhibiting unrealistic behavior. Furthermore, we show that the low Mach enthalpy method accurately simulates thermocapillary flows without introducing spurious phase changes. To reduce computational costs, we solve the governing equations on adaptively refined grids. We investigate two cell tagging/untagging criteria and find that a gradient-based approach is more effective. This approach ensures that the moving thin mushy region is always captured at fine grid levels, even when it temporarily falls within a subgrid level. We propose an analytical model to validate advanced computational fluid dynamics (CFD) codes used to simulate metal manufacturing processes (welding, 3D printing). These processes involve a heat source (like a laser) melting metal or its alloy in the presence of an ambient (inert) gas. Traditionally, studies relied on artificially manipulating material properties to match complex experiments for validation purposes. Leveraging the analytical solution to the Stefan problem with a density jump, this model offers a straightforward approach to validating multiphysics simulations involving heat sources and phase change phenomena in three-phase flows. Lastly, we demonstrate the practical utility of the method in modeling porosity defects (gas bubble trapping) during metal solidification. A field extension technique is used to accurately apply surface tension forces in a three-phase flow situation. This is where part of the bubble surface is trapped within the (moving) solidification front.

Factors and structural paths of the changes in carbon emissions in China's provincial construction industries

The changes in the carbon emissions in China's provincial construction industries are of high complexity. It is essential to understand the changes in the construction carbon emissions (CCEs) in China on the provincial scale. This study evaluates the factors and structural paths of the changes in provincial CCEs in China between 2012 and 2017 using the structural path decomposition analysis. The results show that the emission intensity effect and production structure effect contributed greatly to the reduction of CCEs across various regions, while the final demand effect had contrary impacts. The local nonmetallic mineral products industry (c13), metal smelting and pressing industry (c14), and electricity industry (c24) generally contributed significantly to the emission intensity effect, production structure effect, and final demand effect across most regions. The consumption of local c13, c14, and c24 by the construction industry (c27), namely “local c13→c27”, “local c14→c27”, and “local c24→c27” were generally the important structural paths of the CCEs changes across various regions. Nonlocal industries such as Hebei c14 and nonlocal structural paths such as “Hebei c14→c27” contributed substantially to the CCEs changes in many regions such as Beijing. The emission intensity effect, first-order production structure effect, and final demand effect typically dominated the effects of the critical structural paths of the CCEs changes across various regions. This study can help policymakers better understand the changes in China's provincial CCEs to formulate region-specific emission reduction measures and provide a comprehensive reference for related research.

The diversity of evolution behavior between stoichiometric and non-stoichiometric AlTM intermetallics in Mg melt

In this study, Al-5Ti, Al-18Si-5Ti, Al-12Si-2Sc and Al-12Si-1Sc-1Zr alloys, containing the Al3Ti, Ti7Al5Si12, AlSi2Sc2 and AlSi2(Sc, Zr)2 particles, respectively, were introduced into a Mg melt to understand the morphological and structural evolution behaviors of AlTM intermetallic compounds. Deposition layers at the bottom of the Mg melt were obtained due to the particle settlement. Scanning electron microscope and X-ray diffraction were employed to analyze the phase morphologies and structures of the AlTM intermetallic compounds in the deposition layers. A morphological transformation, characterized by the cracking of particles into fine clusters, was observed in all these AlTM intermetallic compounds, which is promoted by the inward diffusion of Mg atoms. The phase structures of the final particles remained Al3Ti and AlSi2Sc2 when Al-5Ti and Al-12Si-2Sc alloys were introduced into the Mg melt, indicating no structural evolution. However, structural evolutions were detected from Ti7Al5Si12 to Ti5Si4 and from AlSi2(Sc, Zr)2 to SiScZr when they were introduced in the Mg melt. It is hypothesized that the crystal structure, whether stoichiometric or non-stoichiometric, is closely related to the structural evolution behavior of AlTM intermetallic compounds. This work may provide new insights into phase control by introducing one type of metal matrix master alloy into another metal melt.

Magneto‐Optical Control of Ordering Kinetics and Vacancy Behavior in Fe–Al Thin Films Quenched by Laser

One of the issues arising in materials science is the behavior of nonequilibrium point defects in the atomic lattice, which defines the rates of chemical reactions and relaxation processes as well as affects the physical properties of solids. It is previously theoretically predicted that melting and rapid solidification of metals and alloys provide a vacancy concentration in the quenched material, which can be comparable to that quantity at the point of melting. Here, the vacancy behavior is studied experimentally in thin films of the near equiatomic Fe–Al alloy subjected to nanosecond laser annealing with intensities up to film ablation. The effects of laser irradiation are studied by monitoring magneto‐optically the ordering kinetics in the alloy at the very ablation edge, within a narrow (micron‐scale) ring‐shaped region around the ablation zone. Quantitatively, the vacancy supersaturation in the quenched alloy has been estimated by fitting a simulated temporal evolution of the long‐range chemical order to the obtained experimental data. Laser quenching (LQ) of alloys and single‐element materials will be a tool for obtaining novel phase states within a small volume of the crystal.

A numerical study on metallic melt infiltration in porous media and the effect of solidification

The melt infiltration in porous debris is of importance to severe accident prediction and mitigation in nuclear power plants (NPPs), but its mechanism remains elusive. In this study, a computational fluid dynamics (CFD) model is proposed to simulate the evolution of melt infiltration within porous media, incorporating both solidification and melting processes. The CFD model is validated against the experiment (REMCOD facility) and Moving Particle Semi-implicit (MPS) simulation results. Building upon this validated model, the influence of the melt superheat, the initial particle temperature, and its surface wettability on melt infiltration dynamics are mainly analyzed. It is found that increased initial melt superheat enhances melt infiltration length and rate; higher initial particle temperatures promote deeper and faster infiltration, while lower temperatures may result in solidification that blocks further infiltration. Additionally, the wettable particulate bed can enhance melt relocation and heat transfer, but it also accelerates the solidification of the melt, which complicates the infiltration process. Furthermore, phase changes could intensify melt flow instability. This work may expand our understanding of melt infiltration dynamics and pave the way to severe accident modeling in NPPs.

Method for Calculating the Unbalanced Current in Ungrounded Double Wye C-Type Harmonic Filters

This paper presents a methodology to calculate the neutral unbalanced current in C-type filters with an ungrounded double Wye topology; this equipment is widely used in the steel sector to mitigate the harmonic content in electrical installations caused by electric furnaces used in metal smelting processes. A common failure in these filters is the current unbalance caused by the degradation of the capacitor and inductor modules, leading to dangerous surges that affect these components, possible harmonic resonances, and deficient filtering by the equipment. Currently, there are no documented strategies for calculating the neutral current that allow for the proper adjustment of neutral protection in this type of equipment, resulting in catastrophic failures, costly unscheduled shutdowns, and potential harm to plant personnel. In this paper, we propose a methodology for calculating the unbalanced current in double Wye C-type harmonic filters, considering the natural degradation of capacitor and inductor modules and based on on-site measurements of the impedances for each element of the equipment. This allows for the predictive maintenance of these devices and the precise adjustment of neutral overcurrent protection. First, we review the operating principle of C-type harmonic filters and the neutral protection scheme. Then, the calculation methodology is proposed and validated in two practical case studies. In the first case, a 45 Mvar C-type second harmonic filter connected to a 34.5 kV bus is analyzed. In the second case, an 18.5 Mvar C-type second harmonic filter, part of a ±80 Mvar STATCOM system, connected to a 34.5 kV bus is examined. In both cases, these filters reduce the harmonic content in two steel plants: the first connected to a 400 kV bus and the second to a 230 kV bus. The results obtained with the proposed methodology were implemented in the protection device for a neutral current imbalance, considering different degradation values of the capacitors, and compared with the manufacturer’s suggested settings. The discussion highlights the good performance of the proposed methodology, particularly in terms of the protection device’s response speed to a risky unbalanced current.

From Waste to Strength: A Comprehensive Review on Using Fly Ash in Composites with Enhanced Mechanical Properties

This article explores the diverse applications of fly ash (FA), a by-product generated during the combustion of coal. The introductory segment thoroughly comprehends the origins, composition, and widespread occurrence of FA. FA, which comprises an estimated 38% of worldwide power generation, frequently encounters disposal and storage obstacles on account of its classification as non-hazardous waste in the majority of countries. The environmental issues linked to the dispersal of FA are underscored in the problem statement, which further emphasizes the urgency for sustainable alternatives. Due to the fugitive emissions and potential health hazards associated with metal melting in FA, it is critical to investigate novel applications and disposal techniques immediately. Environmental sustainability is a primary focus of research, with the development of synthetic FA composites being one such alternative. The analysis presents significant findings that underscore the wide-ranging applications of FA. These applications include its utilization as a filler in composites, as well as its incorporation into cement and geo-polymerization processes. Notably, (10-20) wt. % Nano-FA enhances epoxy-based composites, showcasing remarkable improvements in tensile strength, flexural strength, and impact resistance. In thermoplastic composites, substantial enhancements occur within the (5–10) wt. % FA range, but exceeding optimal ranges weakens matrix-fiber interaction, leading to diminishing returns. The article emphasizes the criticality of FA in improving the mechanical and thermodynamic characteristics of substances, specifically within the domain of composites. The investigation into FA nanoparticles, including their processing techniques and surface treatments, unveils encouraging prospects for enhancing material characteristics.

Heterogeneous comparative analysis of potentially toxic elements(PTEs)in different media stem from the black rock system under a high geologic background

For the pollution of the environment by potential toxicological elements, more focus on anthropogenic pollution, and few multidisciplinary cross-cutting endogenous pollution investigation based on the geological environment, this study is based on multivariate statistical analysis, geostatistical analysis, multivariate linear analysis, and other methods to combine the pollution of the geological environment and soils and other media, and analyze the heterogeneity and homology of the potential toxicological elements from the level of their sources, spatial and temporal distribution, composition, and homology.The analysis in a typical geological background show that for the average concentrations of Se, B, Cu, V, and Ni, all showed that the contents in soil were greater than those in bedrock.The average values of K2O, CaO, MgO and TiO2 contents in the bedrock are 1.8%, 0.21%, 0.76% and 0.78%, The results of the spatial and principal component analyses indicate that the contents of B, V, and Ni are highly homologous in soil and bedrock. These elements are derived from the smelting of metals, dyeing and printing, and electroplating. In contrast, the contents of Se and Sb are primarily derived from the burning of stone coal. The results of the APCS-MLR modeling indicated that Biomass combustion sources contributed 52.44%, 12.33%, 11.62%, 8.60%, 11.45%, 11.24%, 10.48%, 55.42%, 9.87%, and 14.00% to the concentrations of Cd, Se, B, Cu, V, Ni, As, Bi, Sb, and Cr, respectively, while agricultural surface sources contributed 36.24%, 16.66%, 14.78%, 16.33%, 13.53%, 12.88%, Sb, and Cr to Cd, Se, B, Cu, V, Ni, As, Bi, Sb, and Cr concentrations were 36.24%, 16.66%, 14.78%, 16.33%, 13.53%, 12.88%, 58.77%, 20.31%, 7.70%, and 19.42%, respectively.The soil contact rate of each element was greater than that of bedrock, suggesting that it was more readily adsorbed by the soil. The number of elements with significant correlation in bedrock is greater than that in soil. Elements whose pollution sources are smelting and electroplating are more easily settled and transferred in both soil and bedrock with higher similarity. Elements whose pollution sources are agricultural activities are more effective in settling and spreading in soil. In contrast, the bedrock is affected by the stratigraphic lithology and the spatial structure of rocks, which affect the depositional enrichment of this kind of toxicological elements.