Search Results (23)

Oxygen-free copper wires are widely required in advanced electronic and electrical systems. However, the relationship between deformation-induced microstructure evolution and property variation during severe cold drawing is not fully understood. In this study, oxygen-free copper rods with a diameter of φ20 mm were fabricated by upward continuous casting, followed by multi-pass cold drawing with deformation degrees up to 99.75%. The microstructure evolution, texture transformation, and property changes during drawing and annealing were systematically investigated. It found that increasing drawing deformation progressively elongated, fragmented, and refined the grains, reducing the average grain size from 339.18 μm to 2.12 μm. Dense dislocation cells, substructures, and nanoscale twins were generated during severe deformation, while the texture gradually evolved from random orientations to preferred <111> and <100> textures. After annealing, fine recrystallized equiaxed grains with abundant annealing twins formed together with recrystallization <101> texture. At 99.75% deformation, the tensile strength reached 486 MPa, with an electrical conductivity of 96.7% IACS (International Annealed Copper Standard). After annealing, the electrical conductivity recovered to 101.5% IACS, while the tensile strength decreased to 187 MPa. This work establishes the relationship between severe deformation microstructure evolution and property response in oxygen-free copper, providing guidance for the fabrication of high-strength and high-conductivity copper conductors. Full article

A nano-CuO/ZnO desulfurizer was successfully prepared via a homogeneous precipitation method, and the effects of Cu doping on its microstructure, oxygen species, desulfurization performance, and reaction mechanism were systematically investigated. The results show that an appropriate Cu doping amount (TZ2, Cu:Zn = 1:18.40) significantly reduces the particle size (to ~10.9 nm) compared with pure ZnO (14.3 nm), leading to an increased number of surface-active sites. XPS and TG analyses reveal that Cu incorporation increases the proportion of lattice oxygen and decreases the concentration of oxygen vacancies, indicating that the modification effect of Cu dominates over the particle size effect in regulating surface oxygen species. Despite the reduced oxygen vacancy concentration, the desulfurization performance is markedly enhanced, with TZ2 exhibiting the longest breakthrough time under oxygen-free conditions at room temperature. This improvement is attributed to the strong interaction between highly dispersed Cu species and the ZnO matrix, which promotes H₂S adsorption and activation. Mechanistic studies demonstrate that, unlike pure nano-ZnO, where oxygen vacancy-mediated reactions dominate, the CuO/ZnO system follows a chemisorption-driven pathway involving the formation of copper sulfides and highly reactive polysulfide intermediates. Furthermore, the presence of oxygen significantly influences the reaction behavior, with an optimal oxygen concentration (~10%) maximizing desulfurization performance by balancing the generation of reactive oxygen species and sulfur intermediates. This work provides new insights into the design of high-performance ZnO-based desulfurizers and highlights the critical role of Cu-induced mechanism transformation. Full article

Copper–aluminum layered composites offer a promising combination of high conductivity, light weight, and cost-effectiveness, making them attractive for applications in electric vehicles, electronics, and power transmission. However, achieving reliable interfacial bonding while avoiding excessive work hardening and brittle intermetallic formation remains a significant challenge. In this study, a Cu18150/Al1060/Cu18150 trilayer composite was fabricated through a three-stage high-temperature oxygen-free rolling process. Subsequently, the produced composite was subjected to annealing treatments to systematically investigate the effects of rolling passes, annealing temperature/time on interfacial evolution and mechanical behavior. Results indicate that rolling passes primarily influence interfacial topography and defect distribution. Fewer passes lead to wavy, mechanically bonded interfaces, while more passes improve flatness but reduce intermetallic continuity. Annealing temperature critically governs diffusion kinetics; temperatures up to 400 °C promote the formation of a uniform Al₂Cu layer, whereas 450 °C accelerates the growth of brittle Al₄Cu₉, thickening the intermetallic layer to 18 μm and compromising toughness. Annealing duration further modulates diffusion mechanisms, with short-term (0.5 h) treatments favoring defect-assisted diffusion, resulting in a porous, rapidly thickened layer. In contrast, longer annealing (≥1 h) shifts toward lattice diffusion, which densifies the interface but risks excessive brittle phase formation if prolonged. Mechanical performance evolves accordingly; as-rolled strength increases with the number of rolling passes, but at the expense of ductility. Annealing transforms bonding from a mechanical to a metallurgical condition, shifting fracture from delamination to collaborative failure. The identified optimal process, single-pass rolling followed by annealing at 420 °C for 1 h, yields a balanced interfacial structure of Al₂Cu, AlCu, and Al₄Cu₉ phases, achieving a tensile strength of 258.9 MPa and an elongation of 28.2%, thereby satisfying the target performance criteria (≥220 MPa and ≥20%). Full article

Nanogels provide unique opportunities for stabilizing fragile enzymes through soft, hydrated polymer networks. Here, we report the development of a glutathione peroxidase (GPx)-loaded nanogel (GPxNG) engineered via a mild “grafting-to” epoxy–amine coupling strategy to enhance enzyme stability and antioxidant function. An amphiphilic copolymer composed of methacrylated 2,2,6,6-tetramethyl-4-piperidyl (PMA) and glycidyl methacrylate (GMA) was synthesized by controlled reversible addition–fragmentation chain-transfer (RAFT) polymerization using a poly(ethylene glycol) (PEG) macro-chain transfer agent (macro-CTA), yielding well-defined polymer chains with reactive epoxy groups. Covalent conjugation between polymer epoxides and GPx enzyme surface amines generated soft, PEGylated nanogels with high coupling efficiency, uniform particle sizes, and excellent colloidal stability. The engineered nanogels exhibited shear-thinning injectability, robust storage stability, and non-cytotoxic behavior in RAW 264.7 macrophages. Compared with native GPx enzyme, GPxNGs demonstrated significantly enhanced reactive oxygen species (ROS) scavenging activity, including strong inhibition of lipid peroxidation and copper-induced low-density lipoprotein (LDL) oxidation. Importantly, the nanogels preserved GPx enzyme activity after extended storage, freeze–thaw cycles, and repeated catalytic use, whereas the free enzyme rapidly lost function. This protective effect arises from the nanoscale confinement of the GPx enzyme within the flexible PEG-based network, which limits unfolding and aggregation. Overall, this work introduces a simple and biocompatible “grafting-to” nanogel platform capable of stabilizing redox-active enzymes without harsh conditions. The GPx nanogels combine high enzymatic preservation, potent antioxidant activity, and excellent handling properties, highlighting their potential as a therapeutic nanoplatform for mitigating oxidative stress-associated disorders such as atherosclerosis. Full article

This article presents the results of research on the possibility of extruding oxygen-free copper pipes in bridge dies. The possibility of continuous production of a finished product of any length with a uniformly deformed wall was analysed. One of the most important elements of the work was to determine the shape of the tool (die and bridge) that would allow durable connection of the material. Numerical studies conducted using the commercial computer programme FORGE^®NxT 2.1, including analysis of the distribution of material temperature and hydrostatic pressure in the welding zone of the bridge die affecting the copper joint during the manufacture of tubular profiles, confirmed the validity of the research issue. The results of the numerical studies were supplemented by laboratory tests, confirming the accuracy of the selected variant of the finished product manufacturing process. The process of bonding under conditions of two-part material compression was used for physical modelling of copper welding. The tests were conducted using the Gleeble 3800 metallurgical process simulator with the PocketJaw module. Based on the analysis of the obtained results, it was found that for tubes with a wall-thickness-to-inner-diameter ratio of 0.5, it is justified to use tools with a longer sizing section and welding chamber, as well as a larger mandrel generating-line angle within the welding chamber. Full article

In recent years, there has been a lack of information in the literature regarding the extrusion and connection of closed profiles from oxygen-free copper in bridge dies. Available studies contain information on the processes of extrusion and connection of profiles from aluminium alloys and various types of steel. However, there is a lack of detailed data on the values of technological parameters for which copper is joined in the extrusion process. Therefore, one of the goals of this work is to fill the gap in the literature regarding the extrusion of oxygen-free copper in bridge dies. In this work, the authors determined the thermo-mechanical conditions at which oxygen-free copper will be joined. This paper describes the effects of charge temperature and hydrostatic pressure in the weld zone of a bridge die on copper bonding in the fabrication of tubular profiles. Physical tests of the welding process under the conditions of upsetting a material consisting of two parts were carried out using the Gleeble 3800 metallurgical process simulator with the PocketJaw module in the standard configuration for SICO (strain-induced crack opening) tests. For the numerical simulations, the commercial computer programme FORGE^®NxT 2.1. using the finite element method (FEM) was used. Based on the analysis of the test results obtained, it was found that complete material bonding during the extrusion process could be achieved for a charge temperature higher than 600 °C and a hydrostatic pressure of 45–65 MPa. Full article

Oxidative stress and its relationship to fertility and reproduction is a topic of interest in medicine, especially in the context of the effects of trace elements and micronutrients. Oxidative stress occurs when there is an excess of free radicals in the body, which can lead to cell and tissue damage. Free radicals are reactive oxygen species (ROS) that can be formed as a result of normal metabolic processes, as well as under the influence of external factors such as environmental pollution, UV radiation, and diet. Oxidative stress has a significant impact on fertility. In men, it can lead to DNA damage in sperm, which can result in reduced semen quality, reduced sperm motility and increased numbers of defective sperm, and free radical damage to sperm cell membranes causing a reduction in the number of available sperm. In women, oxidative stress can affect the quality of female reproductive cells, which can lead to problems with their maturation and with embryo implantation in the uterus and can also affect ovarian function and disrupt hormonal regulation of the menstrual cycle. A proper balance of trace elements and micronutrients is key to protecting against oxidative stress and maintaining reproductive health. Supplementation with appropriate elements such as zinc, selenium, copper, manganese, chromium, and iron can help reduce oxidative stress and improve fertility. This work discusses the effects of selected elements on oxidative stress parameters specifically in terms of fertility and reproduction. Full article

Selenium, zinc, copper, and manganese are essential components of antioxidant enzymes involved in the elimination of reactive oxygen species (ROS). Given that cancer cells produce high levels of ROS and the accumulation of ROS can lead to cell death, cancer cells may be susceptible to strategies that reduce ROS elimination. In this work, we prepared several artificial diets that contained normal carbohydrate, protein, and lipid levels but lacked selenium, zinc, copper, or manganese. The anticancer activity of these diets was examined in a metastatic ovarian cancer model, established by injecting ID8 Trp53^−/− murine ovarian cancer cells into the peritoneal cavity of C57BL/6JRj mice. Treatments started 15 days later and consisted of replacing a normal diet with one of the artificial diets for several weeks. A significant improvement in mice survival was observed when the normal diet was replaced with the selenium-free diet. Diets lacking zinc, copper, or manganese showed no significant impact on mice survival. All diets were very well tolerated. The anticancer efficacy of a diet lacking selenium was confirmed in mice with metastatic colon cancer and in mice with metastatic triple-negative breast cancer. These results suggest that diets lacking selenium hold potential for the treatment of metastatic cancers. Full article

With the aim of achieving a sustainable society with green manufacturing, every metal-forming process has been changed to a dry process with the use of limited lubricants via regulation. In parallel, die materials must have sufficient wear resistance to prolong the die life even when forming active metals. A massively nitrogen-supersaturated (MNSed) superalloy was selected as a galling-free die substrate to forge oxygen-free copper wires and bars in dry conditions. A plasma immersion nitriding system was utilized to induce nitrogen supersaturation in CoCrMo, forging dies at 723 K for 21.6 ks with a high nitrogen solute content. Microstructure analyses and microhardness testing proved that the MNSed CoCrMo die had a multilayered structure from the top surface to the depth and that the surface hardness increased up to 1300 HV. Dry, cold forging experiments demonstrated that the oxygen-free copper bar was upset, with a reduction in thickness of 70% in a single stroke under low friction. No fresh copper work debris adhered onto the MNSed CoCrMo die surface. The loading–stroke relationship was used to describe the forging behavior, with low friction and without galling. Full article

Some copper-based metal–organic frameworks show promise for use as electrocatalysts because they allow for an electrode configuration in which copper species with redox and electron-conducting properties are immobilized in a three-dimensional arrangement. This work shows that the synthesis of copper terephthalates (Cu-BDCs) can lead to rigid structures of the copper hydroxyterephthalate-type or flexible structures that are isoreticular to the MOF-2 type, depending solely on the synthesis route. Here, a detailed analysis of the syntheses of the crystals is carried out employing protocols with different solvents as well as conventional or microwave-assisted solvothermal methods. All solids were fully characterized by a combination of characterization techniques, such as FE-SEM, T-XRD, TGA, and FTIR, and their electrochemical redox responses were also evaluated by cyclic voltammetry. A correlation between the Cu-BDCs structures and their electrochemical behaviors was established and a new version of an electroactive copper hydroxyterephthalate was synthesized by a microwave method in 3 h with a dimethylformamide-free protocol. This Cu-BDC was obtained as dispersed nanoflakes with a high amount of copper sites and the capacity to be reversibly electroreduced-oxidized and showed catalytic activity in the oxygen reduction reaction (ORR). Full article

In this work, a metal–ceramic composite target for magnetron sputtering was manufactured by a robotic complex for detonation spraying of coatings equipped with a multi-chamber detonation accelerator. The powder composition (30Mo-30Al-40B4C) was sprayed onto the copper plate base of the composite target cathode. The obtained cathode target with Al-Mo-B4C coating (thickness 280–300 μm) was used to deposit the Al-Mo-B(CN) coating (DC mode) on flat specimens of AISI 316 steel and silicon using equipment for magnetron sputtering UNICOAT 200. The Al-Mo-B4C coating has a lamella-type structure with inclusions of boron carbide particles. The structure and morphology of the coatings were studied using methods of optical analysis, scanning electron microscopy, atomic force microscopy, X-ray analysis, and X-ray photoelectron spectroscopy. Mechanical and tribological properties of the Al-Mo-B(CN) thin coatings were studied using a nanoindenter, a scratch tester, and a tribometer under a fluid-free friction regime at room temperature. The Al-Mo-B(CN) coating (thickness ~1 μm) exhibited a dense homogeneous fine-grained design without columnar elements and had an amorphous structure. The formation of the MoB2 and AlN phase with an admixture of oxygen in the form of aluminum oxide, molybdenum oxide, and boron oxide was determined using XPS analysis. The Al-Mo-B(CN) coating possessed a hardness of 13 GPa, an elasticity modulus of 114 GPa, an elastic recovery of 45%, a friction coefficient of 0.8 against a steel 100 Cr6 ball, and an adhesion strength of 11 N. Full article

The pyrolysis of vegetable oil waste is an alternative way to convert biomass into high-quality second-generation biofuels, with social, economic and environmental sustainability. The present work deals with the pyrolysis of oleic acid as a model compound and an industrial vegetable oil residue on CuNiAl mixed oxide catalysts, derived from layered double hydroxides. Reactions of the oils pre-adsorbed on the catalysts (catalyst:oil mass ratio of 5:1) were performed at 550 °C on a micro-pyrolysis system and the analyses of volatile products were carried out online using GC/MS. Copper addition to NiAl catalysts increased the cracking of oleic acid. Increasing copper content also decreased the formation of aromatics and coke precursors, as well as oxygenated compounds. The CuNiAl catalyst with a Cu/Ni ratio of 0.4 showed strong catalytic activity in the conversion of an industrial vegetable oil residue with a high volume of free fatty acids produced. Compared to the non-catalytic reaction, the catalyst reduced the content of oxygenates and increased the content of hydrocarbons, particularly in the gasoline range (C5–C9). The CuNiAl oxide catalyst was able to convert vegetable oil residues into hydrocarbons in the range of gasoline, kerosene and diesel, and also linear alkylbenzenes as chemical precursors for surfactant production. Full article

CO₂ reduction to CO as raw material for conversion to chemicals and gasoline fuels via the reverse water–gas shift (RWGS) reaction is generally acknowledged to be a promising strategy that makes the CO₂ utilization process more economical and efficient. Cu-based catalysts are low-cost and have high catalytic performance but have insufficient stability due to hardening at high temperatures. In this work, a series of Cu-based catalysts supported by MoO_x were synthesized for noble metal-free RWGS reactions, and the effects of MoO_x support on catalyst performance were investigated. The results show that the introduction of MoO_x can effectively improve the catalytic performance of RWGS reactions. The obtained Cu/MoO_x (1:1) catalyst displays excellent activity with 35.85% CO₂ conversion and 99% selectivity for CO at 400 °C. A combination of XRD, XPS, and HRTEM characterization results demonstrate that MoO_x support enhances the metal-oxide interactions with Cu through electronic modification and geometric coverage, thus obtaining highly dispersed copper and more Cu-MoO_x interfaces as well as more corresponding oxygen vacancies. Full article

Recycling adhesively bonded polymers is inconvenient due to its expensive separation and removal of adhesive residues. To tackle this problem, adhesive technologies are needed allowing debonding on demand and which do not contaminate the surface of the substrate. Direct bonding enabled by oxygen plasma treatment has already achieved substantial adhesion between flat substrates. However, debonding takes place by water, thus limiting the applications of this technology to water-free environments. The work presented in the following shows that this drawback can be overcome by grafting acrylic acid and adding copper(II) ions on the surface of polystyrene. In this process, the number of functional groups on the surface was significantly increased without increasing the surface roughness. The bonding strength between the substrates could be increased, and the process temperature could be lowered. Nevertheless, the samples could be debonded by exposure to EDTA solution under ultrasound. Hence, by combining acrylic acid grafting, variations in the bonding temperatures and the use of copper(II) ions, the bonding strength (5 N to >85 N) and the debonding time under the action of water can be tuned over large ranges (seconds to complete resistance). Full article

The present work aims to systematically investigate the influence of P content on the microstructure and texture evolution of oxygen-free copper during intermediate annealing and final cold rolling. The microstructure and texture evolution were studied by electron backscattered diffraction and transmission electron microscopy. With the addition of P, the grains refined and a large fraction of low angle grain boundaries (LAGBs) emerged after intermediate annealing. The texture transformed from pure metal type for pure Cu to the α-fiber texture which included brass and Goss texture as P was added. The recrystallization temperature increased with the addition of P, and refined grains after the final cold rolling process. The addition of elemental P would reduce the stacking fault energy, and then influence the transformation of the deformation and recrystallization texture of the copper. Accompanied by the evolution of the deformation texture, the recrystallization cubic texture {001}<100> was suppressed and a strong {236}<385> brass recrystallization texture emerged with the addition of elemental P after the intermediate annealing and subsequent final cold rolling process. Full article