Search Results (180)

Aluminum alloy 6061 is widely used in the industrial field, but its poor corrosion resistance has a significant impact on the reliability of equipment components. To address the corrosion resistance issue of 6061 aluminum alloy, a novel Ti-Zr-V conversion coating was prepared on its surface in this study, and the conversion parameters were optimized. The morphology, element distribution and content, composition of compounds, and corrosion resistance of the prepared Ti-Zr-V conversion coating were comprehensively analyzed and evaluated using scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, copper sulfate spot test, and electrochemical experiments. The research results showed that the conversion parameters had a significant impact on the corrosion resistance of the conversion coating. The optimal conversion parameters were a pH value of 4.5 and a conversion time of 5 min, with the optimal addition amount of the auxiliary film former NaVO₃ being 0.6 g/L. Under these conditions, the Ti-Zr-V conversion coating prepared was relatively dense, with fewer grooves, the longest spot resistance time, and the best corrosion resistance. Its surface mainly consisted of titanium dioxide, zirconium dioxide, vanadium pentoxide, V₂O₃, aluminum oxide, and a small amount of fluoride compounds. Electrochemical analysis also demonstrated that the corrosion rate of TiZrVCC decreased by approximately 87.12% compared to the aluminum alloy 6061 substrate, providing a theoretical basis and technical support for the further promotion and use of aluminum alloy. Full article

This investigation meticulously examines the influence of activation energy, thermophoresis, Brownian motion, and magnetic fields on the flow dynamics and heat transfer characteristics of a non-Newtonian hybrid nanofluid comprising aluminum oxide (Al₂O₃), copper (II) oxide (CuO), and ethylene glycol over a horizontally stretching porous wedge. This research addresses the imperative need for enhancing energy transfer and thermal management systems, which possess considerable technical significance and industrial relevance. The flow equations were formulated into ordinary differential equations through the use of similarity transformations, which in turn were solved numerically by employing the spectral relaxation (SR) scheme. The findings indicate that the Brownian motion, activation energy, wedge angle, and magnetic field intensity are pivotal determinants of the system’s flow and thermal behavior. In particular, an increase in the wedge angle correlates with an augmentation of the Nusselt number while concurrently diminishing the thermal and diffusion profiles. A comparative analysis of the current investigation and earlier scrutiny revealed that hybrid nanofluids enhance mass and energy transfer rates in both studies. The novelty of this investigation is anchored in its comprehensive exploration of magneto-flow dynamics and the characteristics of hybrid nanofluids within the context of porous wedge-shaped geometries and external magnetic influences. The findings of this study extend previous research by offering quantitative elucidation regarding how pivotal parameters, such as wedge angles, activation energy, thermophoresis, and Brownian motion, affect heat and mass transfer phenomena, thus laying a robust groundwork for the optimization of hybrid nanofluid applications in engineering and industrial environments. The results are in robust agreement with the existing body of literature, thereby affirming the contributions of this study to the academic discourse in the field. Full article

Copper–aluminum (Cu-Al) wire-bonded devices are widely used in microelectronic packaging; however, corrosion at exposed Cu-Al bimetallic interfaces can lead to Al pad degradation, undercutting, and eventual ball-bond lift-off or open-circuit failure under humid, halide-contaminated conditions. This work presents a scalable post-wire-bond wet-chemical passivation process using octadecylphosphonic acid (ODPA) to simultaneously modify exposed Cu/Pd-coated Cu (PCC) and Al surfaces. The passivation process includes a hydroxylation pretreatment to generate reactive oxide/hydroxide surface sites, followed by ODPA treatment and solvent rinsing to remove weakly adsorbed species. Surface modification was evaluated using contact-angle measurements, reflection–absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). ODPA treatment increased the water contact angle on Cu and Al, confirming a substantial increase in surface hydrophobicity following coating formation. RAIRS identified ODPA-associated aliphatic C-H bands, AFM showed treatment-induced nanoscale surface changes, and XPS supported metal–oxygen–phosphorus interfacial bonding. Under aggressive 100 ppm chloride-ion immersion, ODPA passivation strongly suppressed corrosion-induced ball-bond lift-off across both device platforms. Lift-off decreased from 99.0% to 0.73% for Cu-Al devices and from 23.3% to 0.42% for PCC-Al devices. Collectively, these findings establish an effective, process-compatible post-wire-bond strategy for substantially protecting corrosion-susceptible interfaces and thereby improving the reliability of wire-bonded interconnects in halide-containing environments. Full article

Aluminum nitride (AlN) ceramics are highly regarded for their excellent thermal and electrical properties, making them highly suitable for numerous applications in high-power electronic devices. However, directly bonding copper to AlN substrates remains a significant challenge, mainly due to the strong covalent bonds inherent in AlN, which result in poor wettability of copper on the AlN ceramic surface. To address this issue, the present study proposes a method for directly depositing a dense copper layer on AlN substrates through the atmospheric plasma spraying (APS) process, thereby obtaining a thick copper layer (~30 µm) with excellent comprehensive performance on the AlN substrates. In this study, before performing APS coating, the AlN substrates were first subjected to pre-oxidation treatment to enhance their wettability with the copper layer. Under the optimized atmospheric plasma spraying process parameters, the maximum adhesion strength of copper on the AlN substrates reached 17.56 MPa, along with a low surface resistivity of 2.66 × 10⁻³ Ω·mm and a relatively high room-temperature thermal conductivity of 135 W/m·K. High-resolution transmission electron microscopy (HR-TEM) was used to characterize the interface structure, and the results showed that chemical bonding was formed between the copper layer and the pre-oxidized AlN surface—this bonding effectively enhanced the interface adhesion. In addition, this paper also reports that the atmospheric plasma spraying technology can be used to precisely fabricate copper circuits directly onto AlN substrates. Full article

Thermoacoustic oscillations are excited sound waves in systems with large temperature gradients. Thermoacoustic engines and refrigerators can be constructed using porous materials to enhance the acoustic power produced and facilitate heat pumping for refrigeration. Porous materials can also be utilized as catalytic beds to convert between the two spin-isomers of hydrogen: orthohydrogen and parahydrogen. The conversion between ortho- and parahydrogen is either endothermic or exothermic, and the composition of the isomers manipulates the heat capacity of the fluid. This study experimentally investigates ortho-parahydrogen conversion in a thermoacoustic standing-wave engine with different oxidized catalytic materials. Recorded experimental measurements include the onset temperature ratio, acoustic pressure amplitude, and frequency of the thermoacoustic engine. The results depict a relationship between the oxidized materials and the acoustic amplitude. All oxidized materials promoted an increase in acoustic amplitude versus the pure metallic components. Steady-flow conversion was measured for brass oxide and iron oxide pellets; however, no conversion was detected for aluminum oxide or copper oxide pellets. The initial datapoints provide evidence that future cryogenic hydrogen thermoacoustic devices will need to account for the spin isomer conversion inside the stack. New flow-through regenerating liquefiers can also be constructed, which convert orthohydrogen to parahydrogen during liquefaction. Full article

This meta-analysis combined the results of 61 independent studies published in 2005–2025 to examine polyamine-mediated responses to aluminum, cadmium, lead, chromium, copper, manganese, and selenium stress in plants. The logarithm ratio of responses (lnRR) under the random-effects model was used to calculate the effect sizes. Polyamine application significantly (p < 0.001) enhanced plant growth, with strong increases in root elongation (lnRR = 0.490, 95% CI: 0.362–0.618), fresh weight (lnRR = 0.413, 95% CI: 0.347–0.480), and dry weight (lnRR = 0.475, 95% CI: 0.409–0.541). Oxidative stress was markedly reduced, as reflected by decreases in reactive oxygen species accumulation (lnRR = −0.585, 95% CI −0.682 to −0.487, p < 0.001), hydrogen peroxide content (lnRR = 0.005, 95% CI −0.244 to 0.254, p = 0.968), and lipid peroxidation (lnRR = −0.487, 95% CI −0.578 to −0.397, p < 0.001). The antioxidant defenses were strengthened, and the levels of superoxide dismutase (lnRR = 0.468, p < 0.001) and catalase activity (lnRR = 0.373, p < 0.001) increased significantly. Metal accumulation was consistently reduced in polyamine-treated plants (lnRR = −0.392, 95% CI −0.460 to −0.324, p < 0.001). Supplementary genetic-level data indicated that metal stress triggers polyamines to regulate metal transporters, polyamine biosynthesis genes, antioxidant-related genes, and hormone-signaling pathways. Collectively, these data points make polyamines a key controller of plant metal stress tolerance and offer a quantitative and mechanistic system to apply them to metal-impacted agroecosystems. Full article

Aluminum–lithium (Al–Li) alloys are widely used in aerospace applications because of their high strength-to-weight ratio and reduced density. However, their corrosion behavior can be significantly affected by thermomechanical processing and exposure to chloride-containing environments. In the present study, the corrosion behavior of AA8090-T3 Al–Li alloy was investigated in 3.5 wt.% NaCl solution under simulated marine conditions. The specimens were extracted from a plate and subsequently subjected to annealing and rolling treatments using a specially designed wedge-shaped geometry to generate a continuous strain gradient, enabling the evaluation of deformation-dependent corrosion behavior across different deformation zones. The corrosion behavior was evaluated using potentiodynamic polarization, immersion testing, and surface characterization techniques. The results revealed significant variations in corrosion behavior with thermomechanical condition and deformation zone. The T3 temper-rolled specimen exhibited superior corrosion resistance compared to the annealed and rolled conditions. The lowest corrosion rate of 0.003 mpy was observed for the highly deformed T3 temper-rolled condition, whereas annealed specimens showed higher corrosion susceptibility associated with localized corrosion attack and precipitate-related galvanic activity. Surface characterization confirmed the formation of aluminum hydroxide- and copper oxide-based corrosion products. The study demonstrates the effectiveness of the wedge-shaped rolling methodology for evaluating zone-dependent corrosion behavior in thermomechanically processed AA8090 alloy. Full article

In nuclear power, marine engineering, and other fields, a matching system composed of duplex steel and copper alloy is a common combination for rotating components in a seawater environment. However, this system is susceptible to galvanic corrosion that seriously threatens its service safety and service life, with ZCuAl10Fe5Ni5 being the main component corroded. Additionally, current corrosion research on this system has evident gaps. Specifically, the influence of area ratio on galvanic corrosion remains insufficiently understood, and the action mechanism of Cl⁻ on the ZCuAl10Fe5Ni5-based corrosion product film in seawater, as well as the product evolution path, has not been fully revealed, which restricts the development of targeted protection technologies. This study explores the degradation mechanism of ZCuAl10Fe5Ni5 in a specific high-salinity environment (20,000 mg/L Cl⁻), characteristic of nuclear power plant service conditions. The results show that due to the significant electrode potential difference between the SAF2507 duplex steel and ZCuAl10Fe5Ni5 copper alloy, a stable galvanic couple is formed, with ZCuAl10Fe5Ni5 acting as the anode and undergoing dissolution corrosion. When the area ratio of ZCuAl10Fe5Ni5 (anode) to SAF2507 duplex steel (cathode) is 1:50, a significantly stronger galvanic effect is observed. The high concentration of Cl⁻ in seawater can damage the surface of the ZCuAl10Fe5Ni5-based corrosion product film, leading to intensified local corrosion. The ZCuAl10Fe5Ni5-derived corrosion products have a layered structure mainly comprising a mixed system of Cu-Al-Mg oxides/hydroxides, and the corrosion process is accompanied by selective aluminum depletion corrosion. This study provides insight into the corrosion mechanism and key influencing factors of ZCuAl10Fe5Ni5 in the matching system, as well as a theoretical basis and technical support for the design of compatibility metal materials in a seawater environment and the control of corrosion in ZCuAl10Fe5Ni5. Full article

Background: Trace elements function as essential micronutrients involved in oxidative balance, mitochondrial activity, and cardiovascular metabolism. Cigarette smoking represents a significant source of toxic metals and may disrupt systemic trace element homeostasis. Alterations in micronutrient and metal balance may contribute to oxidative stress, endothelial dysfunction, and myocardial remodeling, which are central mechanisms in the pathogenesis of heart failure with preserved ejection fraction (HFpEF). This study aimed to investigate whether smokers with HFpEF exhibit distinct hair trace element profiles compared with smokers without HFpEF. Methods: In this prospective pilot study, scalp hair samples were collected from adults undergoing clinical evaluation for suspected cardiovascular disease. Trace element concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). Participants were first stratified according to smoking status and subsequently, within the smoker subgroup, according to HFpEF diagnosis based on the Heart Failure Association Pre-test assessment, Echocardiography and natriuretic peptide score (HFA-PEFF) algorithm. Differences in trace element concentrations were analyzed using appropriate statistical tests, with multiple-comparison correction using the Benjamini–Hochberg false discovery rate (FDR). Active smoking was defined as ≥10 cigarettes per day for at least 1 year, and cumulative exposure was quantified in pack-years. Results: Fifty-eight participants were included, including 27 active smokers. In unadjusted analyses, several trace elements differed between smokers with HFpEF and those without HFpEF, including vanadium, lithium, aluminum, and copper. However, after FDR correction, only copper remained significantly elevated in smokers with HFpEF (q = 0.004). Hair copper concentrations were markedly higher in the HFpEF group compared with smokers without HFpEF. These differences were observed alongside echocardiographic features consistent with diastolic dysfunction and structural cardiac remodeling. Conclusions: In this hypothesis-generating pilot study, smokers with HFpEF demonstrated elevated hair copper concentrations, suggesting disturbances in trace element and micronutrient homeostasis. Altered copper metabolism may reflect oxidative stress-related cardiometabolic remodeling associated with HFpEF. These findings raise the hypothesis that cardiometabolic phenotype, rather than smoking exposure alone, may modulate trace element homeostasis in HFpEF; however, causal relationships cannot be established. Full article

Alzheimer’s disease (AD) develops as a progressive dementia condition through the step-by-step breakdown of nerve cells. Neurodegeneration in this context primarily results from metal ions, including copper, iron, zinc, and aluminum, building up in the system. The aggregation of amyloid-beta (Aβ) peptides and oxidative stress generation stem from metal ion involvement acting as defining characteristics of Alzheimer’s disease pathology. We developed a comprehensive mathematical model based on 24 coupled ordinary differential equations (ODEs) to represent the interactions between metal ions, Aβ peptides, reactive oxygen species (ROS), antioxidant defenses, and tau protein phosphorylation. The mathematical model monitors how metal ion concentrations change over time and examines their competitive binding effects, which trigger a series of reactions, resulting in oxidative stress and subsequent tau protein damage. The model uses analytical and numerical mathematical methods to expose nonlinear behaviors and threshold effects while offering mechanistic insights into the course of disease development. This model functions as a quantitative framework for assessing how therapeutic interventions that target metal dyshomeostasis and oxidative stress can potentially affect outcomes. Full article

Surface discharge-induced degradation poses a significant threat to the operational reliability of high-voltage insulation systems. This research investigates the dielectric endurance of polyester-based nanocomposites reinforced with seven distinct nano-additives: iron oxide (Fe₃O₄), copper oxide (CuO), titanium oxide (TiO₂), aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), zinc borate (ZnB) and graphene oxide (GO). Specimens were fabricated at 0.5% and 0.75% weight concentrations and subjected to constant AC electrical stress of 4.5 kV at 50 Hz until failure using the first-plane tracking method. To accurately monitor the aging process, a sophisticated signal processing framework involving Hankel-matrix-enhanced Robust Principal Component Analysis (RPCA) was developed to extract high-frequency discharge features from captured leakage current signals. The degradation characteristics were quantified using various statistical metrics, including Kurtosis, RMS and Burst Discharge Index (BDI). Experimental findings demonstrate that the incorporation of nanoparticles significantly extends the time-to-failure compared to neat polyester, although the effectiveness is highly dependent on both additive type and concentration. At 0.5 wt.%, ZnB exhibited the superior performance in delaying carbonized track formation. However, at 0.75 wt.%, Al₂O₃ emerged as the most effective additive, achieving a maximum endurance time of 31.61 min. In contrast, certain additives like TiO₂ showed a performance decline at higher loadings, likely due to nanoparticle agglomeration. The Hankel-RPCA methodology successfully isolated discharge-specific signatures from background noise, establishing a strong correlation between signal features and material failure stages. This study confirms that the synergy between advanced nanomaterial modification and robust signal processing provides an effective diagnostic tool for monitoring insulation health, offering a vital pathway for the designing of high-performance dielectrics for real-world power system applications. Full article

Copper functions as an exceptionally efficient conductor, garnering considerable interest in electrical and thermal applications; however, its relatively malleable nature and insufficient durability may hinder its structural effectiveness. This study focused on the development of copper-based nanocomposites by reinforcing a copper matrix with co-precipitated CuO/Al₂O₃ nanoparticles (varying from 0 to 10 wt% in increments of 2%). A thorough examination was conducted regarding the microstructural characteristics, mechanical properties, and the electrical and thermal conductivities of the composites. X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) analysis validated the successful synthesis of nano-sized CuO and Al₂O₃ phases, with an estimated crystallite size of 33.2 ± 2.4 nm. Scanning electron microscopy revealed a relatively uniform distribution of nano-oxides within the copper matrix, albeit with signs of particle agglomeration at higher loading levels. The durability of the copper exhibited a significant enhancement attributed to the nano-oxide reinforcement, achieving an 180% increase relative to pure copper with a 10% reinforcement addition. Consequently, the tensile strength increased by approximately 68% (from around 154 MPa to nearly 260 MPa), while maintaining an exceptional level of ductility. The electrical conductivity of copper remained largely unchanged with the addition of nanoparticles; rather, a slight improvement in conductivity and a ~30% rise in thermal conductivity were observed at the maximum reinforcement level. This research work presents a copper-based nanocomposite that offers remarkable potential for applications requiring enhanced strength, wear resistance, and exceptional electrical and thermal conductivity. Full article

Welding copper (Cu) and aluminum (Al) is highly demanded for lightweight and cost-effective manufacturing. However, it faces significant challenges. First, substantial differences in physical properties may lead to high residual stresses and distortion. Second, brittle intermetallic compounds (IMCs) readily form at the interface, severely compromising the joint’s mechanical properties and electrical conductivity. Third, the native oxide film on Al impedes effective wetting and bonding. Therefore, effective control over the interfacial microstructure of the welded joint is essential. This review provides a critical analysis and comparison of several typical welding techniques, including laser welding (LW), friction stir welding (FSW), ultrasonic welding (UW), brazing and soldering, and welding–brazing. These analyses focus on their process characteristics, joint microstructures, and corresponding formation mechanisms. Furthermore, this review synthesizes key strategies for enhancing joint quality, including process parameter optimization, introduction of functional interlayers, and external assistance, aimed at optimizing joint microstructure and minimizing defects. Based on the analysis, this work provides comparative insights into process selection and microstructure control, and highlights future directions: advancing novel methods such as magnetic pulse welding and transient liquid phase bonding; developing intelligent real-time process control to suppress brittle IMCs and associated defects; promoting sustainable practices and establishing standardized performance evaluation; and systematically investigating long-term reliability to support the industrial application of robust Cu/Al joints. Full article

This study presents the electrochemical characterization of a novel, binder-free, plasma-treated aluminum/carbon electrode (“Surge”) using lithium metal half-cells. The low operating potential near 0 V vs. Li/Li⁺ enables the investigation of the electrode’s charge storage mechanisms and stability limits. We compare its electrochemical behavior in coin cells (CR2032) against two reference configurations: (i) the Surge electrode with a thin copper backer (Surge + Cu-backer) and (ii) a commercial graphite electrode on an aluminum current collector (C-REF). The Surge electrode demonstrated ultra-high initial specific capacities of up to approximately 4500 mAh/g (cycle 1) with Coulombic efficiencies exceeding 85% after the formation cycle. The observed capacity significantly exceeds the theoretical value for Li-Al alloying (993 mAh/g), indicating that lithium plating within the porous carbon scaffold contributes substantially to the total charge storage. However, this high performance was limited to approximately 8 to 9 stable cycles. Post-cycling analysis via scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDX) revealed a dominant failure mechanism: partial dissolution and consumption of the Al current collector leading to material redistribution. Quantitative EDX analysis showed a decrease in Al content from 45 at.% to 12 at.% alongside an increase in oxygen content from 8 at.% to 38 at.%, suggesting extensive Al-oxide formation. Critically, in the absence of a backer, Al-containing material deposited onto the stainless-steel cell components. The Cu backer served to redirect these deposits, improving current collection and modestly extending the short-term durability to approximately 1800 mAh/g at cycle 14 (approximately 75% capacity retention). In contrast, the C-REF control cell reached only approximately 1000 mAh/g (cycle 4) before failing within 5 to 6 cycles, underscoring the inherent instability of bare Al at low potentials. This characterization study establishes the Surge architecture as a successful proof-of-concept for ultra-high capacity charge storage and identifies Al dissolution as the dominant degradation mechanism. Future optimization must focus on stabilizing the Al substrate through protective interphases, alloying, or electrolyte engineering. Full article

Numerical simulation has become a powerful and versatile toolkit for investigating gas–solid flow behavior in metallurgical fluidization processes. This review summarizes recent advances in the application of computational fluid dynamics (CFD)-based approaches, particularly the Eulerian–Eulerian and Eulerian–Lagrangian methods, within the field of metallurgical fluidization. It covers model development, particle and bubble dynamics, reactor flow field analysis, and structural optimization. The study demonstrates that numerical simulation plays a crucial role in elucidating fluidization mechanisms, optimizing process parameters, and guiding reactor design. For example, numerical simulation provides key quantitative insights, such as the enhancement of iron ore reduction rates by up to 40% with increased gas velocity and the optimization of reactor cone angles to 5–10° for improved stability, in the design of hydrogen-based iron oxide reduction reactors. However, this review identifies that current research is predominantly focused on iron ore reduction, while numerical studies on fluidized-bed smelting of non-ferrous metals, such as zinc, copper, and aluminum, remain relatively limited. Future efforts should aim to broaden the application of numerical simulation in non-ferrous metallurgy, develop efficient multi-scale coupled computational methods, and integrate artificial intelligence technologies to advance metallurgical fluidization toward greater efficiency, energy savings, and intelligent operation. Full article