Search Results (85)

The electrochemical behavior of copper (II) on glassy carbon from an eutectic mixture of choline chloride (ChCl) and ethylene glycol (EG) was investigated using cyclic voltammetry (CV). The redox and deposition processes were studied for electrolyte concentrations of 0.01 M and 0.5 M Cu(II), with particular attention paid to the effects of different Cu(II) concentrations on the copper deposition potential and morphology of the copper deposits. The CV results showed that the Cu(II) species are reduced to Cu(0) via two separate steps. Higher Cu(II) concentrations in the electrolyte triggered the formation of differently coordinated Cuⁿ⁺ complexes next to the electrode, which shifted the electrodeposition potential of Cu(I)/Cu(0) couples towards more positive values. The Cu deposits were obtained potentiostatically from 0.01 M and 0.5 M Cu(II)-ChCl:EG electrolyte and analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The different copper concentrations in electrolytes induced different morphologies of electrodeposited copper, where the mixture of irregular grains and carrot or needle-like dendrites was obtained from 0.01 M, and rose-like forms were obtained from 0.5 M electrolytes. This study is the first to identify these rose-like forms and the mechanism of their formation, which is discussed in detail. Full article

Cu-Fe in situ composites often face challenges in achieving high strength during cold rolling due to the inefficient transformation of partial Fe phases into fibrous structures. To uncover the underlying mechanisms, this study systematically investigates the co-deformation behavior of Cu and Fe phases in a Cu-10Fe alloy subjected to cold rolling at various strains. Through microstructure characterization, texture analysis, and mechanical property evaluation, we reveal that the Cu matrix initially accommodates most applied strain (ε_vm < 1.0), forming shear bands, while Fe phases (dendrites and spherical particles) exhibit negligible deformation. At intermediate strains (1.0 < ε_vm < 4.0), Fe phases begin to deform: dendrites elongate along the rolling direction, and spherical particles evolve into tadpole-like morphologies under localized shear. Concurrently, dynamic recrystallization occurs near Fe phases in the Cu matrix, generating ultrafine grains. Under high strains (ε_vm > 4.0), Fe dendrites progressively transform into filaments, whereas spherical Fe particles develop long-tailed tadpole-like structures. Texture evolution indicates that Cu develops a typical copper-type rolling texture, while Fe forms α/γ-fiber textures, albeit with sluggish texture development in Fe. The low efficiency of Fe fiber formation is attributed to the insufficient strength of the Cu matrix and the elongation resistance of spherical Fe particles. To optimize rolled Cu-Fe in situ composites, we propose strengthening the Cu matrix (via alloying/precipitation) and suppressing spherical Fe phases through solidification control. This work provides critical insights into enhancing Fe fiber formation in rolled Cu-Fe systems for high-performance applications. Full article

Metallic lithium anodes possess the lowest redox potential (−3.04 V vs. SHE) and an ultra-high theoretical capacity (3860 mAh g⁻¹, 2061 mAh cm⁻³). However, during electrochemical cycling, lithium metal tends to plate unevenly, leading to the formation of lithium dendrites. Moreover, severe electrochemical corrosion occurs at the interface between metallic lithium and traditional copper foil current collectors. To address these issues, we selected corrosion-resistant carbon paper as a lithium metal host and modified a uniform distribution of silver nanoparticles and a F-doped amorphous carbon structure as a highly lithiophilic F-CP@Ag host to enhance lithium-ion transport kinetics and achieve improved affinity with lithium metal. The silver nanoparticles reduced the lithium nucleation energy barrier, while F doping resulted in a LiF-rich solid electrolyte interphase that better accommodated volume changes in lithium metal. These two strategies worked together to ensure uniform and stable lithium metal plating/stripping on the F-CP@Ag host. Consequently, under the conditions of 1 mA cm⁻² and 1 mAh cm⁻², the symmetric cell exhibited stable cycling with a polarization voltage of 8 mV for up to 1400 h. This work highlights the corrosion problem of lithium metal on traditional copper foil current collectors and provides guidance for the long-term cycling stability of lithium metal anodes. Full article

This review aims to provide an up-to-date report on the state of the art of electrolytes based on (quasi-)ionic liquids for sodium batteries. Electrolytes based on conventional ionic liquids are classified into one-anion- and two-anion-type electrolytes according to the number of different anions present in the media. Their application for sodium-based batteries is revised, and the potential advantages of two-anion-type electrolytes are highlighted and rationalized based on the higher tunability of interactions among the different electrolyte components enabled by the presence of two different anionic species. Next, the synthesis and properties of liquid ammonia solvates (aka liquid ammoniates) are presented, with a focus on their use as alternative electrolytes. Attention is paid to some of the outstanding properties of ammoniates, notably, their high conductivity and sodium concentrations, together with their ability to sustain dendrite-free sodium deposition, not only on sodium but also on copper collectors. Finally, the prospects and limitations of these electrolytes for the development of new sodium-based batteries, including anode-less devices, are discussed. Full article

Protection against microbiologically influenced corrosion (MIC) is critical for materials used in aquatic environments, as MIC accelerates material degradation and leads to faster structural failure. Copper (Cu) has the potential to substantially improve the MIC resistance in alloys. In this study, high-entropy alloy (HEA) coatings containing Cu were deposited using DC (Direct Current) magnetron sputtering to enhance the corrosion resistance and mechanical properties of various substrates. Two CuCrFeMnNi HEA compositions in the form of bulk alloys and PVD (Physical Vapor Deposition) coatings, with 5% and 10% Cu, were analyzed for their microstructural, mechanical, and anticorrosive characteristics. Deposition parameters were varied to select the optimal values. Microstructural evaluations using SEM-EDS (scanning electron microscopy and energy dispersive X-ray spectroscopy), XRD (X-ray diffraction), and AFM (atomic force microscopy) revealed uniform, dense coatings with good adhesion composed of dendritic and interdendritic BCC (body-centered cubic) and FCC (face centered cubic) structures, respectively. Microhardness tests indicated improved mechanical properties for the samples coated with developed HEAs. The coatings exhibited improved corrosion resistance in NaCl solution, the 10% Cu composition displaying the highest polarization resistance and lowest corrosion rate. These findings suggest that Cu-containing HEA coatings are promising candidates for applications requiring enhanced corrosion protection. Full article

The direct energy deposition arc process is widely used for fabricating medium and large components with moderate geometric complexity but often results in coarse microstructures and inconsistent hardness. This study introduces a hybrid manufacturing approach combining the friction stir burnishing process with the direct energy deposition arc by a gas–metal arc welding technique to refine the microstructure and enhance the microhardness of components fabricated from austenitic stainless steel 316L. Our former study used an aluminum alloy (A5052) friction stir burnishing tool, demonstrating significant microhardness improvement and grain refinement. However, it also faced notable challenges under high-heat and -friction conditions, including the effect of material adherence to the workpiece during processing. Therefore, this study introduces a newly developed friction stir burnishing tool made from copper (C1100) and compares its performance with the aluminum alloy tool regarding microhardness enhancement and microstructure refinement. The results indicate that the specimen processed by direct energy deposition arc combined with the copper friction stir burnishing tool demonstrated the best overall performance in grain refinement and hardness enhancement. Specifically, it achieved the highest average microhardness of 250 HV at 50 µm depths, compared to 240 HV for the aluminum alloy tool. The statistical analysis showed that both tools led to significant improvements over specimens processed without them. The statistical analysis confirmed a notable reduction in secondary dendrite arm spacing across all depths, with the copper tool demonstrating the most refinement. Additionally, a preliminary investigation of corrosion behavior revealed tool-dependent differences. Overall, this study offers a promising approach to improving additive manufacturing, particularly for industries with less stringent surface finish requirements. It could potentially reduce post-processing time and cost. Future research should explore different process parameters and assess long-term corrosion performance to develop this hybrid technique further. Full article

This paper presents experimental results regarding the development of new alloys from the binary ZnCu and ternary ZnCuMg systems. The alloys had controlled chemical compositions and were annealed at 300 °C and 400 °C, with holding times of 5 h and 10 h, followed by air cooling. Mechanical properties (tensile strength, yield strength, elongation, and elastic modulus) were determined. Structural analysis conducted after different heat treatments revealed that homogenization transforms the dendritic structure into a granular structure with intergranular eutectic presence. Biodegradation behavior showed that the ternary alloy exhibits higher degradation rates than the binary alloy. Applying the homogenization heat treatment has a good influence on the binary alloy only, not on the ternary alloy. Our research shows that that the complex alloying of zinc with copper and magnesium may improve cavitation behavior, doubling both the MDE_max parameter and cavitation resistance expressed by R_cav. Full article

The ruins of the Imperial City of the Minyue Kingdom were an important site of the Minyue Kingdom during the Han Dynasty. Characteristic bronze arrowheads unearthed from the East Gate, with their exquisite craftsmanship, provide important physical evidence for studying ancient bronze casting technology and the military activities of that time. However, there is still a lack of systematic research on the alloy composition, casting process, and chemical stability of these arrowheads in long-term burial environments. The bronze arrowheads that were found in the East Gate warehouse are the subject of this study. Metallographic analysis, scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were used to carefully examine their composition and microstructure, as well as the casting process characteristics. The findings reveal the following: (1) The East Gate bronze arrowheads primarily consist of copper–tin binary alloys, and certain samples exhibit a lead (Pb) content of up to 11.19%, potentially due to element addition during casting or element migration in the burial environment. (2) The metallographic structure shows that the sample matrix has a typical α-dendrite structure, indicating that a high-temperature casting process was used, and then a certain surface treatment was performed to enhance corrosion resistance. (3) Under a scanning electron microscope, it was observed that a three-layer structure was formed on the surface of the arrowhead, including a fully mineralized layer, an intermediate transition layer, and the original core tissue. (4) The detection of molybdenum (Mo) in some samples suggests a close relationship between the complexity of the buried soil environment and human activities. (5) By comparing the microstructure and corrosion degree of the longitudinal section and the cross-section, it was found that the longitudinal section has a stronger corrosion resistance due to its denser structure. Comprehensive analysis shows that the technical details of the bronze arrowheads unearthed from the Minyue Imperial City in terms of material selection, casting process, and later use reflect the outstanding achievements of the Minyue Kingdom in the field of bronze manufacturing in the Han Dynasty. Full article

The electrochemical CO₂ reduction reaction (CO₂RR) to formate offers a promising pathway to mitigate the energy crisis and realize carbon neutrality. Bismuth (Bi), as a metal catalyst for the CO₂RR, is considered to have great potential in producing formate, yet hindered in low current density and selectivity. Herein, we constructed an oxide-derived copper foam substrate (OD-Cu) to improve the electrocatalytic properties of Bi dendrites loaded on its surface. Bi electrodeposited on the OD-Cu (Bi/OD-Cu) grows as pinecone-like dendrites, exhibiting a high formate faradaic efficiency (FE_formate) of 97.2% and a formate partial current density of ~24 mA·cm⁻² at −0.97 V vs. RHE (reversible hydrogen electrode) in an H-cell. Notably, the Bi/OD-Cu electrode demonstrates an FE_formate of 95.8% at −0.97 V vs. RHE and a total current density close to 90 mA·cm⁻² at −1.17 V vs. RHE in a neutral flow cell. The experimental studies reveal that the remarkable CO₂RR performance of the Bi/OD-Cu results from the electron transfer from Cu to Bi, which optimizes adsorption of the CO₂^•− and boosts reaction kinetics. This study emphasizes the crucial role of substrate engineering strategies in enhancing catalytic activity and shows the possibility for a porous metal electrode in advancing the industrialization of formate production. Full article

In this work, electron beam welds between Cu and Al plates were formed using different power modes, namely 1800 W, 2400 W, and 3000 W. The structure, microhardness, and tensile strength of the raw materials and the weld seams were studied. The low power of the electron beam resulted in the improper penetration and insufficient depth of the weld seam. The low power resulted in high cooling rates, which hindered the nucleation of the copper and aluminum particles. A number of intermetallic compounds (IMCs) were formed, including the metastable Cu₉Al₄ one. An increase in the power of the electron beam reduced the cooling rate and increased the miscibility between the materials. This resulted in the formation of a mostly homogeneous structure comprising an αAl solid solution and dendritic eutectic CuAl₂ intermetallic compounds. A preferred crystallographic orientation of the aluminum phase was detected regarding the sample prepared using a power of 3000 W, forming a specific texture towards the {111} family of crystallographic planes, which is the closest-packed structure. This plane characterizes the highest chemical activity and the highest plasticity. As a result, this sample exhibited the best chemical bonding between the IMCs and the aluminum matrix and the best microhardness and tensile test values. Full article

This study explored how post-casting heat treatment and forging affected the tribological and microstructural characteristics of 0.20% beryllium (Be)-added CuAl₁₀Ni₅Fe₄ alloys. The heat-treated CuAl₁₀Ni₅Fe₄ microstructure exhibits a copper-rich α (alpha)-solid-solution phase, a martensitic β (beta)-phase, and diverse intermetallic κ (kappa)-phases, such as leaf-shaped κ_I, thin κ_III, and black globs. Adding 0.20% beryllium to CuAl₁₀Ni₅Fe₄ alloys enhanced the dendritic arm thickness, needle-like shape, and κ-phase quantities. Significant κ_IV- and κ_II-phase precipitation was observed in the tempered β-phase. Beryllium improves the aluminum matrix’s microstructure. Forging greatly reduced the microstructural thickness of CuAl₁₀Ni₅Fe₄ and CuAl₁₀Ni₅Fe₄-0.20% Be alloys. The forging process also developed new κ_IV-phases. Wear resistance and hardness improved with beryllium. The CuAl₁₀Ni₅Fe₄-0.20% Be alloy had the highest hardness values (235.29 and 255.08 HB) after solution treatment (ST) and tempering (T) after casting and forging (F). The CuAl₁₀Ni₅Fe₄-0.20% alloy with Be added had the best wear after solution treatment, tempering, and forging. The CuAl₁₀Ni₅Fe₄-0.20% Be alloy demonstrated a 0.00272 g weight loss, a 1.36 × 10⁻⁸ g/N*m wear rate, and a 0.059 friction coefficient at 10,000 m after forging (F). Full article

In this paper, the solidification microstructure characteristics of metastable immiscible Cu20Fe alloys under natural cooling conditions and subsequent cold rolling were analysed. The findings demonstrate that the Cu20Fe alloy underwent a liquid–solid transformation under natural cooling conditions. The equiaxed Cu matrix and the Fe dendrites exhibited elongation into ribbon-like structures parallel to the cold rolling direction. Following cold rolling, the mean grain size of the Cu20Fe alloy was considerably refined, and the mechanical properties were improved. After cold rolling, the Cu matrix formed both {112}<111> copper and {110}<112> brass textures. Furthermore, the strengthening mechanisms of the cold-rolled Cu20Fe alloy are primarily dependent on the strengthening of grain boundaries and work hardening. This provides an economically friendly method for the preparation of Cu-Fe alloys with high Fe compositions. Full article

Zinc-based batteries (ZBBs) have proven to be tremendously plausible for large-scale electrochemical energy storage applications due to their merits of desirable safety, low-cost, and low environmental impact. Nevertheless, the zinc metal anodes in ZBBs still suffer from many issues, including dendrite growth, hydrogen evolution reactions (HERs), corrosion, passivation, and other types of undesirable side reactions, which severely hinder practical application. The modification of Cu-based current collectors (CCs) has proven to be an efficient method to regulate zinc deposition and prevent dendritic growth, thereby improving the Coulombic efficiency (CE) and lifespan of batteries (e.g., up to 99.977% of CE over 6900 cycles after modification), which is an emerging research topic in recent years. In this review, we provide a systematic overview of the modification of copper-based CCs and their application in zinc metal anodes. The relationships between their modification strategies, nano-micro-structures, and electrochemical performance are systematically reviewed. Ultimately, their promising prospects for future development are also proposed. We hope that this review could contribute to the design of copper-based CCs for zinc-based batteries and facilitate their practical application. Full article

Copper smelting slag is a significant potential resource for cobalt and copper. The recovery of copper and cobalt from copper slag could significantly augment the supply of these metals, which are essential to facilitating the transition to green energy while simultaneously addressing environmental concerns regarding slag disposal. However, the complex mineral composition of copper slag poses an enormous challenge. This study investigated the mineralogical and chemical characteristics of copper slag, which are vital for devising the most effective processing techniques. XRD and FESEM-EDS were employed to examine the morphologies of copper slag before and after the reduction process. The effects of borax and charcoal (carbocatalytic) reduction on phase transformation were evaluated. The XRD analysis revealed that the primary phases in the copper slag were Fe₂SiO₄ and Fe₃O₄. The FESEM-EDS analysis verified the presence of these phases and yielded supplementary details regarding metal embedment in the Fe₂SiO₄, Fe₃O₄, and Cu phases. The carbocatalytic reduction process expedited the transformation of copper slag microstructures from crystalline dendritic to amorphous and metallic phases. Finally, leaching experiments demonstrated the potential benefits of carbocatalytic reduction by yielding high extractions of Cu, Co, and Fe. Full article

In this study, we demonstrate the electrodeposition of copper nanoparticles (NPs) on pencil graphite electrodes (PGEs) utilizing sodium dodecyl sulphate (SDS) as a soft template. The utilization of the surfactant had an impact on both the physical arrangement and electrochemical characteristics of the modified electrodes. The prepared Cu-SDS/PGE electrodes had hierarchical dendritic structures of copper NPs, thereby increasing the surface area and electrochemical catalytic activity in comparison with Cu/PGE electrodes. The Cu-SDS/PGE electrode showed excellent catalytic activity in reducing hydrogen peroxide, resulting in the sensitive and selective detection of hydrogen peroxide. The electrode exhibited a good sensitivity of 21.42 µA/µM/cm², a lower limit of detection 0.35, and a response time of less than 2 s over a wide range spanning 1 µM to 1 mM of hydrogen peroxide concentrations. The electrodes were also highly selective for H₂O₂ with minimal interference from other analytes even at concentrations higher than that of H₂O₂. The approach offers the benefit of electrode preparation in just 5 min, followed by analysis in 10 min, and enables for the quantitative determination of hydrogen peroxide within 30 min. This can be achieved utilizing a newly prepared, cost-effective electrode without the need for complex procedures. Full article