Search Results (1,692)

The growing importance of renewable energy sources and the implementation of circular economy principles highlight the need for the rational management of biomass combustion by-products. The aim of this study was to assess the chemical composition of ash produced through the combustion of various biomass fractions from four varieties of common hazel (Corylus avellana L.) in the context of its potential for secondary use. The analysis covered the shells, husks, leaves, and shoots of the following varieties: Kataloński, Olbrzymi z Halle, Olga, and Webba Cenny. Combustion was carried out under laboratory conditions at a temperature of 550 °C, and the content of macro- and micro-element oxides (P₂O₅, K₂O, CaO, SO₃, Cl, SiO₂, MnO, Fe₂O₃, NiO, CuO) and potentially toxic elements (ZnO, TiO₂, Cr₂O₃) was determined using the EDXRF method. The results showed significant variation in the chemical composition of the ash depending on the biomass fraction and variety. The highest P₂O₅ content was found in the leaves of the Kataloński variety (5.02), whilst the highest K₂O concentration was found in the husk of the Olga variety (47.33%). The maximum CaO content was found in the leaves of the Webba Cenny variety (32.60). The leaf and husk fractions were characterised by the highest content of nutrients of fertilising importance, whilst the shells exhibited the lowest values for most macronutrients. The content of potentially toxic elements was low. The results obtained indicate that the selective utilisation of specific fractions of hazel biomass can increase the efficiency of mineral recovery whilst maintaining environmental safety, in line with the principles of the circular economy. Full article

To obtain ultrahigh strength Cu alloy strip for board-to-board connectors, a CuNiSiMgMn multi-element high-solute alloy was designed, and high-temperature short-time solid solution was utilized to optimize the properties of this alloy. The evolution in microstructure and properties of the cold-rolled CuNiSiMgMn alloy strip during high-temperature short-time solid solution, aging, and further cold-rolling are investigated. The results reveal that there are high-density Ni_xSi precipitates and deformation defects in the original cold-rolled CuNiSiMgMn alloy strip. During a solid solution at 1000 °C, recrystallization primarily occurs between 15 and 30 s, while precipitate decomposition starts at a solid solution time of ~30 s and is almost complete 10 s later. With further increase in the solid solution time, the grain size of the alloy grows rapidly, but the residual precipitate particles exhibit little change. Upon aging at 500 °C for 2 h and a further 80% cold-rolling, nano-sized precipitates are formed, yielding high-strength alloy strips. The 80% cold-rolling increases the microhardness by 12% and decreases the electrical conductivity by 3% IACS. The strip solid solution-treated for 35 s exhibits the maximum strength, with a tensile strength of >950 MPa and a conductivity of >30% IACS. Further extension of the solid solution time decreases both the tensile strength and elongation. This work clarifies the critical time of recovery, recrystallization, and precipitate decomposition of the CuNiSiMgMn alloy during high-temperature solid solution and provides guidance for industrial production. Full article

Steel slags are major by-products of steelmaking, and their variable composition complicates recycling and valorization strategies. This study investigates four representative slag samples obtained from different production pathways at an industrial steel plant in Uzbekistan, using a combined multi-scale characterization approach. Bulk elemental composition was determined using X-ray fluorescence (XRF), while microstructural and phase-level analysis was carried out using scanning electron microscopy with energy-dispersive spectroscopy (SEM–EDS), including both point analysis and automated phase mapping. The XRF results revealed two distinct compositional groups, with one slag dominated by Mn–Si–O chemistry and three slags characterized by high Ca content. SEM–EDS phase mapping further resolved these differences at the microscale, identifying manganese silicate and oxide phases in the Mn-rich slag, Ca–F–O dominant phases in two slags associated with fluorite flux addition, and a more heterogeneous Ca-based system with localized enrichments of Mn, Zn, and Cu in the fourth sample. The combined results demonstrate that slag composition strongly reflects steel grade and fluxing practice. The integration of XRF and SEM–EDS provides a robust framework for linking bulk chemistry with phase distribution, improving slag classification and supporting informed decisions for reuse and environmental management. Full article

Wood biomass ash (WBA) from thermal power plants is often landfilled despite its potential as a secondary raw material. This study adopts a circular economy perspective to assess the physicochemical properties, valorization potential, and environmental risks of WBA, aiming to support its use in agriculture and environmental management. Comprehensive characterization included pH, cation exchange capacity (CEC), proximate and elemental composition, and selected organic contaminants, including polycyclic aromatic hydrocarbons (PAHs). The WBA exhibited a strongly alkaline pH (10.55), moderate CEC (4.36 cmol kg⁻¹), and high ash content (78.32%), with lower nutrient content than other biomass ashes. Major elements included Ca (6.84%), K (2.90%), and Si (3.19%), while nitrogen was absent. Potentially toxic elements (PTEs) such as As, Cd, and Ni were below detection limits; Cr, Cu, Pb, and Zn remained within most regulatory thresholds, although Zn exceeded some limits. ΣPAHs were low (0.05 mg·kg⁻¹), indicating minimal environmental concern. Despite reduced nutrient richness, the ash demonstrated suitability as a liming agent and supplementary nutrient source, provided that Zn levels are managed and nitrogen is supplemented. These results support the redirection of WBA from disposal to beneficial use, advancing circular economy goals and contributing to more sustainable and resilient agricultural systems. Full article

Zeolite P was synthesized by hydrothermal treatment of coal fly ash and applied to the individual removal of six heavy metals (Pb²⁺, Ni²⁺, Cu²⁺, Cr³⁺, Hg²⁺, Cd²⁺) from aqueous solutions. Characterization by SEM-EDS, FTIR, BET, XRD, zeta potential, and XPS revealed a BET surface area of 30 m²/g, Si/Al ratio of 1.63, and pH_pzc of 3.2. Batch experiments at the natural solution pH of 3.9 in all cases (C₀ = 10, 100, 200 mg/L; t = 1–60 min) yielded an apparent selectivity sequence at C₀ = 200 mg/L of Hg²⁺ (10.47 mg/g) > Pb²⁺ (9.12) > Ni²⁺ (2.18) > Cr³⁺ (2.05) > Cu²⁺ (1.82) > Cd²⁺ (1.26), where Hg²⁺ and Pb²⁺ reached near-equilibrium while the remaining metals were still approaching it at t = 60 min. Weber–Morris and Boyd analyses confirmed three sequential diffusion stages with a concentration-dependent shift from film to intraparticle diffusion control through the narrow GIS channels (3.1 × 4.5 Å). Ion exchange was identified as the dominant mechanism based on convergent kinetic, diffusion, XPS, and selectivity–electronegativity evidence (r = +0.76). A leakage-free machine learning framework combining physicochemical descriptors with experimental variables was tested under three cross-validation strategies of increasing stringency. Gradient Boosting achieved R² = 0.979 ± 0.043 (repeated K-Fold) and R² = 0.880 on six completely held-out kinetic curves. An ablation study confirmed that physicochemical descriptors are essential (experimental-only models yielded negative R²). SHAP feature importance rankings were consistent with established ion exchange selectivity theory. This work demonstrates that group-level validation, physics-informed descriptors, and systematic ablation testing are able to identify both the capabilities and the boundaries of small-dataset ML when testing for metal kinetics prediction. Full article

Aluminum–silicon (Al-Si) alloys are widely used in aerospace, automotive manufacturing, power electronics, marine engineering and other fields due to their excellent physical properties. However, their corrosion resistance is insufficient in harsh service environments. In this study, a variety of characterization methods were adopted, including scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical measurements (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization), immersion corrosion tests, and scanning vibrating electrode technique (SVET). The results show that the appropriate heat treatment regime can significantly enhance the corrosion resistance of the alloy, while improper aging parameters will aggravate the corrosion tendency. The optimal heat treatment regime is solution treatment at 500 °C for 4 h followed by aging at 200 °C for 48 h. Under this condition, the corrosion current density (i_corr) is as low as 79.30 μA/cm², and the low-frequency impedance modulus and phase angle in EIS tests are optimal. The as-extruded alloy exhibits severe localized corrosion, while the heat-treated alloy transforms into mild and uniform corrosion. The underlying mechanism is that heat treatment induces the formation of uniformly distributed nanoscale Mg₂Si and Al₃(Sc,Zr) precipitates, which synergistically improve the corrosion resistance of the alloy by weakening micro-galvanic coupling and facilitating the formation of a stable passive film. Full article

Copper (Cu) smelting slags are considered secondary reserves of technology metals (TMs) and base metals (BMs), which are crucial for the transition to renewable energy and mechatronic applications. In this study, thermochemical and experimental analyses were conducted to investigate the pyrometallurgical extraction of TMs and BMs from Cu smelting slag. FactSage thermochemical simulations and smelting experiments were carried out at temperatures from 1300 to 1600 °C and with carbon (reductant) additions of 2% to 10% relative to the mass of the feed slag. The results showed that during smelting, gallium (Ga), germanium (Ge), cobalt (Co), and copper (Cu) deported into the iron-based alloy product. Zinc (Zn) and lead (Pb) oxidised to ZnO and PbO, respectively, which were subsequently collected as fumes. The produced alloy mass was more sensitive to carbon addition than to smelting temperature variation. The TM and BM contents in the alloy decreased with increasing carbon addition in the feed; this was attributed to dilution by Fe, Si, and C from the increasing reduction of iron and silicon oxides in the feed slag and dissolution of C in the alloy. High recovery degrees of TMs and BMs in the alloy stream—over 90% for Co and Cu, over 50% for Ga, and over 70% for Ge—were achieved when smelting at 1500 °C with 4% carbon addition. The final alloy comprised 70.5% Fe, 6.6% Co, 23.6% Cu, 0.11% Ga, and 0.13% Ge. The fumes primarily comprised ZnO and, to a lesser extent, PbO, with recovery degrees over 90% for Zn and Pb. These alloy and fume products would be processed following conventional hydrometallurgical separation and purification processes to produce high-purity metals. The pyrometallurgical extraction of TMs and BMs presents an opportunity for the valorisation of Cu smelting slag dumps, especially in Southern Africa, aiming to attain zero-waste industrial processes. Full article

Achieving a balanced combination of mechanical performance and corrosion resistance remains a critical challenge restricting the broader application of Al–Zn–Mg–Cu alloys in aerospace, marine, and transportation industries. In this investigation, the addition of Si significantly enhances the mechanical properties of the alloy. Among them, the alloy containing 0.35Si has the best corrosion resistance, which is closely related to the transformation of precipitates. A non-monotonic relationship between Si content and corrosion resistance was observed. At low Si levels, the simultaneous precipitation of η, T, and GPB-II phases leads to a large electrochemical potential difference among these phases, which promotes micro-galvanic corrosion. With increasing Si content, the microstructure evolves toward the dominance of GPB-II precipitates, thereby reducing the internal potential difference and improving corrosion resistance. However, excessive addition of Si will lower the equilibrium solid phase temperature, resulting in overburning during the solid solution treatment process and a significant decrease in corrosion resistance. In addition, lowering the solution treatment temperature effectively improves corrosion resistance by suppressing the formation of remelted spheres and low-melting-point brittle phases along grain boundaries. These phases can form strong micro-galvanic couples with the matrix, accelerating anodic dissolution. Therefore, by adding an appropriate amount of Si and optimizing the solid solution temperature, a corrosion-resistant high-strength Al-Zn-Mg-Cu-Si alloy can be obtained. This strategy also provides a broader compositional and heat-treatment design window, which could be further expanded through the incorporation of rare-earth (RE) elements. Full article

Hybrid atomization represents a novel method for powder production with high cooling and crushing capacities, but previous studies have primarily focused on tin and aluminum alloy systems. In present study, FeSiBNbCu nanocrystalline powders were prepared using a hybrid atomization system and the effects of atomization parameters on the sphericity of the powders and soft magnetic properties of the nanocrystalline magnetic powder cores (NMPCs) were investigated. Orthogonal experiments reveal that atomization pressure is the most critical factor affecting powder size, while melting temperature primarily influences sphericity. By optimizing the atomization parameters, the nanocrystalline powders with a high sphericity of up to 91.2% can be achieved, and the core loss at 1 MHz@20 mT of the corresponding NMPCs is reduced by 59.2% to 464 mW/cm³. This study provides valuable guidance for the fabrication of Fe-based nanocrystalline powders with excellent soft magnetic properties via hybrid atomization. Full article

The reconstruction of detrital flux, paleoclimate, paleosalinity, paleo-primary productivity, paleohydrodynamic conditions, and paleo-water depth enhances understanding of sedimentary processes and their drivers during deep-time greenhouse-icehouse transitions, such as the Eocene–Oligocene transition. This study uses detailed geochemical analyses of major oxides and trace elements in sediment samples collected from the Beni Suef Formation (Bartonian–Priabonian) and the Maadi Formation (Priabonian) in the southern Tethys shelf (Egypt, northeastern Desert). Detrital proxies, including Si/Al, Ti/Al, and Zr/Al, indicate an enhanced influx of terrigenous sediments in the middle portion of the Qurn Member of the Beni Suef Formation, as further supported by noticeable facies variations, particularly the transition from shale to coarser silt- and sand-sized fractions. Paleoclimate indicators (Sr/Ba, Rb/Sr, K₂O/Al₂O₃, and Sr/Cu) point to a climatic shift from humid to arid conditions, consistent with the regional Late Eocene aridification across the Tethyan realm. Paleosalinity proxies (Sr/Ba, Ca/Al, and Mg/Al×100) suggest episodic intensification of open-marine influence and a reduction in freshwater input, with an upsection increase in Sr/Ba ratios, reflecting phases of enhanced marine water settings or decreased terrestrial runoff. Primary productivity was evaluated using multiple geochemical proxies, including P, Ni/Al, Cu/Al, P/Al, P/Ti, and Babio ratios. These collectively indicate generally low primary productivity interrupted by intervals of enhanced paleoproductivity or increased organic matter export to the sediments. This interpretation is further supported by the low total organic carbon (TOC) values. These results highlight the sensitivity of the southern Tethys shelf to Middle–Late Eocene climatic variability and the key role of prevailing paleoenvironmental conditions in controlling sediment supply, water chemistry, and biological productivity. Full article

A systematic study was conducted on the influence of Cr on the property evolution and precipitation behavior of Cu-Ni-Si alloys. Results indicate that Cu-Ni-Si alloys containing 0.33 at% Cr exhibit superior mechanical properties after three-stage cryogenic rolling and aging, achieving a tensile strength of up to 862 MPa. The addition of Cr induces competitive precipitation behavior between Cr and Ni for Si. It promotes the precipitation of Cr₃Si phases at various scales while suppressing the formation of Ni₃Si phases. Concurrently, it enhances the precipitation of fine nanoscale precipitation-hardening phases Ni₂Si, optimizing the alloy’s precipitation hardening effect. Furthermore, the addition of Cr suppresses dislocation annihilation. The formation of finer precipitates pins the dislocations introduced during cryogenic rolling and impedes their motion, thereby enhancing the alloy’s strength and hardness. The alternating and staggered distribution of soft and hard microzones in the Cr-containing alloy results in more uniform overall properties of the sample. However, the reduced proportion of soft microzones slightly decreases the alloy’s electrical conductivity. Full article

Stricter drinking water regulations intensify the need to replace leaded brasses in fittings. This work reports preliminary results on internally coated fittings using the wrought zinc alloy ZnAl15Cu1Mg (ZEP1510). A straight-tube Model Geometry 1 was lined internally with HDPE by gas-assisted injection molding, achieving a continuous barrier of 1.55–1.70 mm without altering the external envelope. A press-type T-fitting (32–32–32) was defined as Model Geometry 2 to benchmark forgeability; process layout (FEM) and warm-forging trials are summarized. Recycling relevance was addressed via a partial-melt (drip-off) route, which removed a substantial polymer fraction but left measurable residues. A production-cycle PCF from material production to finished tee indicates 3.156 kg CO₂e for ZEP1510 vs. 5.385 kg CO₂e (CuZn40Pb2) and 6.301 kg CO₂e (CuZn21Si3), i.e., 41.85% and 50.06% savings. These findings establish manufacturability, indicate recycling feasibility, and quantify a CO₂ advantage, outlining the next steps toward lining complex geometries and drinking water compliance. Full article

The Xinqiao Cu-S polymetallic deposit is located in the Tongling ore concentration area of the Middle-Lower Yangtze River metallogenic belt. The orebodies consist of skarn orebodies and stratiform sulfide orebodies, but the genetic link between them remains controversial. In this study, magnetite was used as a proxy to systematically constrain the hydrothermal evolution from the intrusion to the contact zone and further to the stratiform orebodies. A representative drill hole (E603) was logged, and samples were systematically collected from the Jitou pluton outward to the contact zone. Composite samples from the 8–28 m interval were crushed and prepared as resin mounts for integrated TIMA automated mineralogy, BSE textural observation, and in situ LA-ICP-MS trace element analysis. Five types of magnetite (Mt1 to Mt5) were systematically identified. Mt1 occurs as inclusions within feldspar in the quartz monzodiorite. It exhibits typical magmatic magnetite characteristics and contains grid-like ilmenite exsolution, indicating crystallization during the late magmatic stage. Mt2 is distributed in the interstices of magmatic minerals, commonly showing hematitization and replacement of ilmenite exsolution lamellae by titanite. Its trace element geochemistry displays magmatic–hydrothermal transitional features. Mt3–Mt5 in the skarn and stratiform orebodies are paragenetic with retrograde alteration minerals (e.g., epidote, chlorite, and actinolite) and sulfides, and are characterized by low Ti, Al, and V contents and high Mg, Mn, and Sn contents, indicating a hydrothermal origin. From Mt3 to Mt5, (Ti + V) and (Al + Mn) decrease, while Zn and Mn increase, accompanied by a decrease in the (Si + Al)/(Mg + Mn) ratio. This reflects a trend of decreasing fluid temperature and progressively enhanced wall-rock buffering. The Mg-in-magnetite geothermometer yields relatively consistent results for Mt1–Mt3, but anomalously high temperatures for Mt4–Mt5. This suggests that the elevated Mg activity in the fluid, caused by reaction with carbonate wall rocks, can significantly influence the calculated temperatures. Therefore, this geothermometer should be used cautiously for magnetite in the outer skarn zone and interpreted in combination with other temperature constraints. The textures, paragenetic mineral assemblages, and trace element characteristics of magnetite collectively reveal a continuous mineralization process linking the skarn and stratiform orebodies at Xinqiao, providing robust mineralogical and geochemical evidence for the contribution of Yanshanian magmatic–hydrothermal activity to the stratiform mineralization. Full article

The influence of pre-deformation on the microstructure and mechanical properties of a Mg-rich high-Cu Al-Mg-Si-Cu alloy was systematically investigated by hardness measurement, tensile test, and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). With the increase in pre-deformation strain (0–10%), the hardness and strength of the alloy after PB hardening increased progressively, accompanied by a continuous reduction in tensile elongation. Notably, increasing pre-deformation strain from 2% to 10% did not bring a significant enhancement in bake hardening response, despite the gradual improvement in the strain hardening capability of the alloy. An optimal pre-deformation strain of 5% is identified, which enabled the alloy to achieve a superior and industrially feasible combination of strength and ductility, balancing practical forming demand (T4 temper) and service performance (PB state). Pre-deformation can significantly affect the morphology and atomic structure of precipitates for the alloy. Dislocations introduced by pre-deformation acted as heterogeneous nucleation sites, inducing the formation of elongated and string-like precipitates along dislocation lines. A distinct Cu segregation behavior was observed in the pre-deformed alloy with the majority of Cu atoms segregated at the precipitate/α-Al interface, which was in sharp contrast to their dominant distribution within the precipitate interior in the non-pre-deformed alloy. These findings provide new insights into deformation-assisted precipitation regulation in Mg-rich high-Cu Al-Mg-Si-Cu alloys and offer practical guidance for optimizing the strength–ductility synergy of such alloys for automotive lightweight manufacturing applications. Full article

To address the lack of suitable glass systems for silicon nitride (Si₃N₄) surface metallization, which requires high wettability and thermal stability, and robust bonding between the copper layer and the ceramic substrate, a novel Bi₂O₃-TeO₂-B₂O₃-CuO glass system was developed. This study systematically investigated the influence of Bi₂O₃ concentration, glass properties, optimized paste composition, and brazing mechanism using phase analysis, microstructural characterization, particle size statistics, thermal analysis, and tensile testing. An optimal glass composition containing 20 mol% Bi₂O₃ was identified, exhibiting high thermal stability (ΔT = 224 °C) and a coefficient of thermal expansion of 9.63 × 10⁻⁶ °C⁻¹. At a brazing temperature of 750 °C, the glass demonstrated excellent wettability with a contact angle of 27°. A conductive paste comprising 94 wt% Cu and 6 wt% glass yielded a thick film with a minimum resistivity of 6.25 μΩ·cm and a maximum tensile strength of 25.2 MPa. Mechanism analysis revealed that the superior wettability drives the liquid glass phase to form a thin intermediate layer that significantly reinforces adhesion. These findings contribute to the research and development of subsequent novel glass systems with superior performance. Full article