To enhance the high-temperature oxidation resistance of high-purity oxygen-free copper wire, this study prepared copper wires using 6N high-purity copper as the matrix with trace additions of Ag, P, Cr and Ni. Oxidation behavior of the wires in air at 300, 400, and 500 ℃ was systematically investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to analyze the morphology, thickness, and phase composition of the oxide films. Results indicated that the introduction of trace elements significantly affected the characteristics of the oxide films. Ag addition thickened the oxide film and promoted formation of CuO at high temperatures. P incorporation refined the oxide film structure and inhibited oxygen diffusion. Synergistic effect of Cr and Ni effectively enhanced the density of the oxide film and promoted Cu₂O formation, significantly strengthening the texture of Cu(111) and other crystal planes, thereby improving overall oxidation resistance.

Flocculating sedimentation is a critical step in the thickening and dewatering of tailings during the backfilling process in mines. A certain iron mine in Liaoning has a complex and diverse mineral composition, with a significant proportion of fine-grained tailings, which poses challenges such as slow sedimentation rates and high overflow turbidity for the flocculating sedimentation process. To study the flocculating performance and sedimentation mechanism of tailings from the iron mine, experiments were conducted using whole tailings as the main test material. Results of natural sedimentation and flocculating sedimentation tests were compared. Single-factor method was combined to carry out flocculant selection tests were conducted, with clarity of the supernatant and sedimentation rate being the main evaluation indicators. Ultimately, 655S flocculant with the best sedimentation effect was selected for subsequent flocculating sedimentation experiments. By adjusting flocculant unit consumption and filling slurry concentration, the effects of these two factors on the performance of slurry flocculation and sedimentation were analyzed separately. When feed concentration was below 20%, the optimal flocculant addition was controlled in the range of 15±5 g/t, with the underflow concentration reaching 62.61%. Findings of this study provided a theoretical basis for improving the quality and efficiency of fine tailings backfilling in similar mines, and had significant practical value and engineering guidance significance.

Steel shed reinforced concrete combined support technology has been well applied in recent engineering practices. Based on tests and post-evaluations, this technology is considered highly suitable for complex geological conditions such as fractured and weak surrounding rocks in terms of technical comprehensive feasibility. However, there is little detailed research or analysis about this composite support method and related critical technologies. This paper, adopting methods of references study, practical cases study and data analysis, studied and summarized the technical feasibility of adopting steel shed reinforced concrete composite support method through post evaluation of the open slot section construction of a large copper mine's belt inclined shaft. It outlined key techniques and corresponding applicable situations of four core processes: construction of steel shed, construction of reinforced concrete arch skeleton, integrated construction of concrete work, and construction of transition section between open slot and underground tunnel. The aim was to provide references for support method selection and construction of copper mine roadway support under similar working conditions.

To prevent fire incidents, investigating fire traces and identifying the cause of the fire is a primary task in fire forensic evidence identification. Analysis of microscopic characteristics of copper conductors after a fire is an effective method for this purpose. This study simulated the temperature, time, and atmospheric conditions of a fire environment, generating fires caused by overcurrent faults, to investigate surface morphology, cross-sectional grain shape, and size of copper conductors after a fire. As the temperature increased and duration extended, oxidation degree of the copper conductor deepened, and grains continuously grew, exhibiting an axial shape. At 400 ℃, the grain size was 7~11 μm. At 600 ℃, it increased to 8~14 μm. At 800 ℃, it reached 13~17 μm. During the grain growth process, a large number of twins appeared due to low stacking fault energy. Average grain size of copper conductors was directly proportional to both annealing temperature and time, with temperature having a more significant impact. Linear fitting results showed that activation energy for grain boundary migration during grain growth was 0.68 kJ/mol. Under actual overcurrent fault conditions, the failure copper conductor formed molten beads and dendrites at the fracture site, indicating that an excessive current in the circuit caused the conductor to overheat, ultimately leading to fracture, with abnormal grain growth occurring near fracture zone.

In this study, Cu-Ni-Sn-P (C19040) alloy strip materials with different compositions were prepared by horizontal continuous casting followed by multiple cold rolling and heat treatment processes. Effects of Sn and Ni mass fraction variations on the mechanical properties, softening resistance, and thermal contraction of Cu-Ni-Sn-P alloy strip materials were investigated. Results indicated that an increase in Sn mass fraction enhanced mechanical properties and softening resistance of Cu-Ni-Sn-P alloy through solid solution strengthening. However, excessive Sn mass fraction exacerbated Sn segregation, which worsened the thermal contraction behavior. An increase in Ni mass fraction promoted the formation of more Ni-P precipitates, significantly improving the softening resistance. When mass fraction of Sn was 1.5% and that of Ni was 0.85%, the alloy exhibited superior comprehensive properties, with a hardness of 174HV, tensile strength of 565 MPa, elongation of 4.3%, thermal contraction rate of 0.006%, and softening resistance hardness of 141HV. These properties met the requirements for lead frame materials.

Ammonia plays an important role in human activities, which is used widely in various industries with noticeable economic values. The main method currently used in ammonia synthesis is Haber-Bosch method, which requires high-temperature or high-pressure conditions, suffering low efficiency and high energy cost. In comparison, electro-reduction of nitrite for ammonia production is a NH₃-selective green chemistry process with low energy consumption. Cu-based materials are chosen as common catalyst materials in electro-production of ammonia owing to the abundance of source materials and high reaction activity towards nitrite. State-of-art Cu-based materials applied in electro catalysis of nitrate for ammonia production are mainly: metallic Cu, metallic-doped Cu-based materials, alloys, Cu oxide, Cu-containing polymetallic oxide, Cu-containing metal-organic framework (MOF), etc. These catalysts improve performances of ammonia production with different mechanisms, such as surface modulation, electron structure modulation, synergy of catalytic active centers, construction of built-in electric fields, etc. This paper aims to integrate performances and mechanisms of different Cu-based catalysts for electrochemical production of ammonia, and to provide reference for future research in this field.

Accurate determination of germanium (Ge) content in smelting dust is of great guiding significance for scientific recycling of smelting dust. Smelting dust contains a large amount of metastannic acid, which can encapsulate the sample, making it difficult to achieve complete decomposition using hydrochloric acid (HCl) and nitric acid (HNO₃). A variety of sample dissolution methods were investigated, and complete sample decomposition was achieved by using sodium peroxide (Na₂O₂)-hydrochloric acid-nitric acid for sample digestion. Meanwhile, the temperature was controlled to avoid the volatilization loss of germanium. The analytical line of Ge at 259.253 nm was selected, and contents of sample solution were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Overall, a method for determination of germanium in smelting dust was established. Under the optimized experimental conditions, mass concentration of germanium in the range of 0.50~15.00 µg/mL showed a good linear relationship with the emission intensity, with a linear correlation coefficient (r) of 0.99973, and a detection limit of 0.0013% (mass fraction). The matrix effect was investigated, and results showed that the coexisting elements in smelting dust had no significant influence on the determination of germanium. When the proposed method was applied to the determination of germanium in smelting dust samples, the relative standard deviation (RSD, n=11) ranged from 1.15% to 2.82%, and the recovery rate was in the range of 97.7% to 100.8%.

Aluminum bronze alloys are a type of bronze alloy formed by mainly adding aluminum to copper, along with other alloying elements such as nickel and iron. Aluminum bronze alloys feature excellent mechanical properties, wear resistance and corrosion resistance, and are widely used as gears, valves and propellers. With rapid advancement of industrial technology, increasingly stringent requirements are being imposed on various properties of aluminum bronze. For traditional as-cast aluminum bronze, the presence of casting defects combined with complex multiphase structure makes it susceptible to failure under specific service conditions. The composition, microstructure, and properties of the alloy should be systematically optimized and improved in a targeted manner to meet specific requirements of service conditions. This paper investigated intrinsic relationship among preparation process, microstructural characteristics, as well as mechanical, corrosion, and wear properties of aluminum bronze alloys. It provided a comprehensive review of recent advancements in the development of high-performance aluminum bronzes through alloying, heat treatment, additive manufacturing, surface modification, and other processes. Corrosion resistance and friction-wear resistance of aluminum bronze under various technological conditions were systematically summarized and analyzed before potential future research directions were outlined.

Grain boundary diffusion technology has emerged as a pivotal approach to overcome bottlenecks of high cost and significant remanence loss in traditional single-alloy methods by precisely regulating the distribution of heavy rare earths (HREs), thereby markedly enhancing the coercivity of NdFeB magnets. This study proposed composite diffusion sources formed by blending Tb-Al-Cu HRE alloys with pure Nd powder at varying ratios, systematically investigating their diffusion modification effects on both HRE-free and HRE-containing substrates. Experimental results demonstrated that under optimal diffusion source ratios, the maximum coercivity enhancements for the two substrates reached 1.036 T and 0.959 T, respectively, with remanence attenuation controlled within 0.59 kGs and 0.43 kGs. When TbAlCu-to-pure-Nd ratio was 3∶2 (for HRE-free substrates) or 2∶3 (for HRE-containing substrates), the magnets exhibited optimal comprehensive performance, achieving 48UH and 45EH grade levels, respectively. Microstructural analysis revealed that HRE-free substrates developed increased grain boundary phases, refined grains, and core-shell structures after diffusion, while HRE-containing substrates showed a significant increase in non-magnetic grain boundary phases. By designing composite diffusion sources, this study achieved remarkable magnetic performance improvements with low HRE consumption, offering a novel strategy for the green preparation and resource-efficient utilization of high-performance NdFeB magnets.

Surface defects in C19400 copper-iron alloys significantly degrade both electrical conductivity and mechanical properties, posing a key limitation on their application in high-end semiconductor packaging and electronic components. In this paper, origins and microscopic morphology of compositional defects in C19400 copper strips were systematically investigated. Distribution behavior of elements in the copper matrix was first predicted using Miedema model for thermodynamic calculations of Cu-Fe-P system. Subsequently, the defective samples were characterized in terms of microstructure and composition through methods including spark discharge optical emission spectrometry, scanning electron microscopy, and energy-dispersive spectroscopy. Results revealed the presence of various inclusion defects and precipitation in C19400 copper strips. Specifically, oxide inclusions appeared as irregular flakes; carbides aggregated as dark fine particles in localized areas; phosphides were distributed inside pits; hard inclusions were embedded as irregular particles within the pits, and precipitates aligned in elongated forms along the rolling direction. Traceability analysis indicated that compositional defects introduced during the melting and casting stages remained through manufacturing process to strip stage. Subsequent rolling and annealing treatments further altered the size and distribution of these inclusions. This study clarified the evolution path and microstructural characteristics of these defects, providing a theoretical and experimental basis for optimizing processing of C19400 and enhancing reliability of this material in high-end electronic applications.