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Finite Element Modeling of Thermo-Viscoelastoplastic Behavior of Dievar Alloy under Hot Rotary Swaging

CMES - Computer Modeling in engineering and sciences 2025年第3期142卷 3115-3133页

作者： Izák, Josef Benč, Marek Opěla, Petr Department of Manufacturing Technology Faculty of Mechanical Engineering Brno University of Technology Brno61600 Czech Republic Department of Metallurgical Technologies Faculty of Materials Science and Technology VŠB Technical University of Ostrava Ostrava70800 Czech Republic

The paper deals with the FEM (Finite Element Method) simulation of rotary swaging of Dievar alloy produced by additive manufacturing technology Selective Laser Melting and conventional process. Swaging was performed at a temperature of 900◦C. True flow stress-strain curves were determined for 600◦C–900◦C and used to construct a Hensel-Spittel model for FEM simulation. The process parameters, i.e., stress, temperature, imposed strain, and force, were investigation during the rotary swaging process. Firstly, the stresses induced during rotary swaging and the resistance of the material to deformation were investigated. The amount and distribution of imposed strain in the cross-section can serve as a valuable indicator of the reduction in porosity and the texture evolution of the material. The simulation revealed the force required to swag the Dievar alloy. It also showed the evolution of temperature, which is important for phase transformation during solidification. Furthermore, microstructure evolution was observed before and then after rotary swaging. Dievar alloy is a critical material in the manufacture of dies for high-pressure die casting, forging tools, and other equipment subjected to high temperatures and mechanical loads. Understanding its viscoelastoplastic behavior under rotary swaging conditions is essential to optimize its performance in these demanding industrial applications. Copyright © 2025 The Authors.

关键词： Steel ingots

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Quantum Interference in a Molecular Analog of the Crystalline Silicon Unit Cell

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Journal of the American Chemical Society 2025年第19期147卷 16602-16610页

作者： Hight, Matthew O. Pimentel, Ashley E. Siu, Timothy C. Wong, Joshua Y. Nguyen, Jennifer Carta, Veronica Su, Timothy A. Department of Chemistry University of California RiversideCA92506 United States Materials Science & Engineering Program University of California RiversideCA92506 United States

This manuscript describes the emergence of destructive σ-quantum interference (σ-DQI) in sila-adamantane, a molecule whose cluster core is isostructural with the crystalline silicon unit cell. To reveal these σ-DQI effects, we take a bridge-cutting approach where we conceptually pare sila-adamantane down to its bicyclic Si[3.3.1] and linear oligosilane forms. Scanning tunneling microscopy break-junction (STM-BJ) measurements reveal that conductance in single-molecule junctions of the tricyclic sila-adamantane is 2.7-times lower than their bicyclic Si[3.3.1] analog. The only structural difference between their cluster cores is a remote dimethylsilylene bridge that is present in sila-adamantane yet absent in Si[3.3.1]. Density functional theory calculations reveal that this dimethylsilylene enforces C3 symmetry at the sila-diamondoid bridgeheads, allowing each electrode to couple into the three cluster bridge dimensions equally. Though each bridge alignment is sterically equivalent, they have profound electronic differences: when electrodes align with the long branches of sila-adamantane, strong σ-DQI interactions occur between frontier molecular orbitals that suppress electronic transmission across the molecular junction. We exploit these alignment-dependent σ-DQI effects to create new forms of stereoelectronic conductance switches, where a reversible mechanical stimulus controls which pathway through the diamondoid framework the electrodes align through. This represents the first example of dynamic modulation of σ-DQI and enables us to achieve switching ratios (average on/off ∼5.6) higher than previously reported σ-stereoelectronic switches. These studies reveal how the innate dimensionality and symmetry of crystalline silicon influence charge transport at its most fundamental level, and how these principles can be harnessed to control quantum interference in single-molecule electronics. © 2025 The Authors. Published by American Chemical Society.

关键词： Molecular orbitals

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Numerical Investigation on Transient Response of Transpiration Cooling with Phase Change

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International Journal of Gas Turbine, Propulsion and Power Systems 2025年第1期16卷 1-9页

作者： Liu, Taolue Liu, Yifei Ding, Rui He, Fei Wang, Jianhua CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy Engineering University of Science and Technology of China Anhui Hefei230027 China Northwest Institute of Nuclear Technology Xi an710024 China

Transpiration cooling with phase change is a novel active thermal protection method with higher cooling efficiency. The modified two-phase mixture model and the multi-domain coupling computation are adopted to study its transient response. Different fluctuation periods of coolant mass flux and different thermal conductivities of the porous matrix are discussed, respectively. The simulation results show that there are clear delay and accumulation effect in the transient response, and the coolant injection pressure is much more sensitive than the temperature to the coolant mass flux. Moreover, both temperature and injection pressure have their own extreme values during transient response. Then, the instability on the porous matrix surface is closely related to the location of the coolant phase transition. Using the porous matrix with greater thermal conductivity can not only help to reduce the surface temperature of the structure under steady condition, but also has stronger stability under transient condition. The research of this work is of great guidance and practical importance for the extension of the application of transpiration cooling with phase change in the real environment. Copyright ©2025 Taolue Liu, Yifei Liu, Rui Ding, Fei He and Jianhua Wang.

关键词： Thermal conductivity of liquids

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Dense carbon nanofiber self-supporting electrode fabricated by orientation/compaction strategy for high volumetric lithium storage capacity

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Progress in Natural science:materials International 2025年第1期35卷 229-237页

作者： Haihui Liu Chaoqun Chen Qiang Xu Yan Song Xiangwu Zhang Chang Ma Tianjin Municipal Key Lab of Advanced Fiber and Energy Storage Technology Tiangong University CAS Key Laboratory of Carbon Materials Institute of Coal Chemistry Chinese Academy of Sciences Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science Wilson College of Textiles North Carolina State University

Low bulk density greatly restricts the large-scale application of electrospun carbon-based fiber membrane as electrode in energy storage devices. To solve the above challenges, herein an orientation-compaction densification strategy is proposed to enhance the bulk density and volumetric capacity of PAN-based carbon nanofiber membranes as self-supporting electrode used in lithium-ion batteries（LIBs）. Specifically, highly-oriented fibers are achieved by high-speed roller collecting during electrospinning, and compaction densification is conducted by hot-pressing treatment. The effects of collecting speed and hot-pressing pressure on the morphology, conductivity,bulk density, tensile strength, and flexibility of the obtained carbon nanofiber membrane are *** to conventional fiber membranes, of which fibers are disorderly stacked, the oriented fiber membrane is much easier to achieve dense stacking by compaction. The obtained dense carbon nanofiber membrane demonstrates a bulk density of 0.566 g cm-3, and shows a significantly-enhanced volumetric capacity(318.3 mA h cm-3), high-rate performance(86.6 mA h cm-3at 5 A g-1), and satisfactory cycling stability when used as selfsupporting electrode of LIBs.

关键词： Bulk density Densification Electrospinning Orientation-compaction Volumetric capacity

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Feasibility Study of Precoated Binder-Type Electric Arc Furnace Oxidizing Slags as Aggregates for Cement Mortar 1st

Feasibility Study of Precoated Binder-Type Electric Arc Furn...

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1st International Conference on Net-Zero Built Environment: Innovations in materials, Structures, and Management Practices, NTZR 2024

作者： Lin, Wei-Ting Sprince, Andīna Hebda, Marek Mucsi, Gábor Cheng, An Pan, Huang-Hsing Department of Civil Engineering National Ilan University Yilan Taiwan Institute of Civil Engineering Faculty of Civil and Mechanical Engineering Riga Technical University Riga Latvia Department of Materials Engineering Faculty of Materials Engineering and Physics Cracow University of Technology Kraków Poland Institute of Raw Materials Preparation and Environmental Technologies University of Miskolc Miskolc Hungary Department of Civil Engineering National Kaohsiung University of Science and Technology Kaohsiung Taiwan

ISBN: (纸本)9783031696251

The study used electric arc furnace oxidizing slag (EAFOS) to substitute natural fine aggregates. However, EAFOS replacement may cause volumetric instability. Therefore, a cement, fly ash, or slag layer was coated with EAFOS as a precoated technique. Then, the effect of EAFOS on engineering properties was investigated, and the optimum amount of EAFOS was identified. The amount of coated binders was set at 20%, 25%, 30%, 35%, and 40% of the weight of EAFOS, and the water-to-binder ratio (w/b) of the coated binders was fixed at 0.50 to 0.20. The proportion of EAFOS replacing fine aggregates was 10%, 20%, 30%, 40%, and 50%, and the w/b of the mortar was fixed at 0.55. The results showed that the proportion of precoated binder was 30% of the EAFOS and the w/b was 0.30. Curing time was up to 28 days, and slag was the appropriate precoated binder. Maximum compressive strengths of mortars made with precoated EAFOS were 42.94 and 56.96 MPa at 7 and 28 days (40% replacement for fine aggregates). The maximum compressive strengths of specimens without coated EAFOS were 36.67 and 47.55 MPa at 7 and 28 days (the identical replacement). The drying shrinkage of 40% precoated slag specimens was 0.054% at 7 days and 0.074% at 28 days. The appearance of the specimens did not reveal any abnormality after 28 days of immersion in water at 70 °C. The precoated technique adopted in this study can be used as a stabilization procedure for replacing natural fine aggregates with EAFOS. © The Author(s) 2025.

关键词： Mortar

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The Effect of Ca Addition on the Behavior of Bioresorbable Duplex Phase Mg-Li-Zn-Ca Alloys

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JOM 2025年 1-14页

作者： Ezenwajiaku, Sochima S. Gallo, Flavia C. Yang, Yang Manuel, Michele V. Department of Materials Science and Engineering Rhines Hall University of Florida Gainesville USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh USA

Magnesium (Mg) is a promising candidate for degradable implants due to its biocompatibility, mechanical properties, and natural degradation. However, Mg’s rapid hydrogen evolution, low ductility, and limited strength restrict its utility. Alloying Mg with lithium (Li) improves ductility and formability, while zinc (Zn) adds antibacterial properties and enhances strength. Despite this potential, limited research on Mg-Li systems, particularly in the duplex phase where HCP and BCC phases coexist, leaves gaps in understanding their corrosion behavior and mechanical properties. This study explores the effect of calcium (Ca) addition on the properties of the Mg-Li-Zn system within the duplex phase. Two quaternary alloys, Mg-Li-Zn-Ca, with 0.3 wt.% and 1.0 wt.% Ca were prepared and subjected to solution and aging treatments. Microstructural analysis reveals an increase in the volume fraction of the BCC Mg phase with Ca addition, refined precipitate sizes, and formation of Mg2Ca and Ca2Mg6Zn3 in Ca-containing alloys. mechanical testing revealed 5–20% improvements in ultimate and yield strengths in Ca-containing alloys. The corrosion resistance improved, reducing surface area loss and hydrogen gas evolution rates by 15% and 1.4 mL/cm2/day, respectively. Meanwhile, all Ca-containing alloys demonstrated negligible toxicity to endothelial cells, underscoring their potential as biocompatible materials for degradable implants.

关键词： Corrosion resistant alloys

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Lactic acid oligomer grafted gum acacia encapsulated controlled release nitrogen fertilizer for crops improvements and greener soil sustainability

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South African Journal of Chemical engineering 2025年 53卷 158-175页

作者： Wasie, Yihun Periyasamy, Selvakumar Tesfaye, Melakuu Department of Chemical Engineering Shambu Campus Wollega University Shambu Ethiopia Department of Chemical Engineering School of Mechanical Chemical and Materials Engineering Adama Science and Technology University Adama 1888 Ethiopia Department of Biomaterials SIMATS Saveetha Dental College and Hospitals Saveetha University Chennai 600077 India

Nitrogen (N) is an essential nutrient for plant growth and productivity. Urea contains 46 % N, the highest content of solid nitrogenous fertilizers, but it is limited in its delivery system. In this research work, urea was encapsulated in a hydrophobic bio-adhesive, which was synthesized through a poly-condensation reaction of lactic acid (LA) and gum acacia (GA) to control its dissolution rate in water. Box-Behnken method of design expert software was used to investigate the effect of process parameters on the grafting efficiency and urea release rate. The grafting efficiency and the urea release rate were inversely proportional. The grafting of lactic acid oligomer (LAO) chains at the O–H and N–H functional groups of the GA backbone was confirmed by FTIR and NMR analyses. The solubility and hydrophobicity tests of LAO-g-GA exhibit that both increase with grafting efficiency. The study found that the urea release rate increases with the temperature of the medium and urea concentration but decreases with the increase in pH of the medium. The results observed from the study could help commercialize slow-release urea fertilizer for the effective use of nitrogen and maintain a pollution-free environment. © 2025 The Author(s)

关键词： Biofertilizer Controlled nitrogen release Essential nutrient Green soil sustainability

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Biogas and biohydrogen production using the main agricultural biomasses generated in Brazil: An integrative analysis to contribute to the implementation of energy decarbonization

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International Journal of Hydrogen Energy 2025年 137卷 190-201页

作者： dos Santos, Maele Costa Nadaleti, Willian Cezar Przybyla, Grzegozr Machado, Jones Bittencourt Environmental and Energy Engineering Lab – LEAE Engineering Center – CEng Postgraduation Program in Environmental Sciences - PPGCAmb The Federal University of Pelotas – UFPel Rio Grande do Sul Pelotas Brazil Department of Thermal Technology Silesian University of Technology Poland Post-graduation Program in Materials Science and Engineering - PPGCEM. The Federal University of Pelotas – UFPel Rio Grande do Sul Pelotas Brazil

The use of bioenergy feedstocks, agricultural and forest residues constitute a viable decarbonization design with regards to biofuel production. Nevertheless, aspects within agriculture that can be related to this process for instance, include: technology and infrastructure, policies, land use, environmental factors among others. Solving these challenges needs research, technological intervention, supportive policies and acclaimed association among agriculture and energy departments, especially considering that agricultural and forest residues are an abundant source of biomass which can be converted into renewable energy, for example, biogas and hydrogen. This study provides an assessment of the capacity for generating biogas and biohydrogen using the primary biomasses produced in Brazil's agricultural sector, specifically from rice, corn, soybeans, and wheat as alternative bioenergy resources. Data regarding production and waste creation were collected from the Statistical and Geographical Information of Brazilian Agriculture at the Institute of Geography and Statistics of Brazil and the Energy Research Company. Corn and Soybean straw showed the highest potentials for biohydrogen (PH) production, accounting to 6,67 E+09 m3/year and 5,56 E+09 m3/year respectively. The energy production using the generated biogas showed the most satisfactory results compared to biohydrogen, with the highest generation values of 222 TWh of energy for corn straw, 187 TWh for soybean straw. The total accumulated biogas and biohydrogen produced from the residual biomass of Brazil's four main permanent crops was approximately 8.25 E+10 and 1.33 E+10 m3/year, respectively. The generation of biogas and hydrogen holds significant potential for fostering a more sustainable energy future. By utilizing the unique advantages of these two methods—biogas as a waste-to-energy option and hydrogen as a clean and adaptable energy source—we can develop a more robust, varied, and low-carbon energy frame

关键词： Straw

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Effects of Interface Anisotropy on the Solidification Morphology of Zinc Alloys and Development of Data Assimilation for Their Estimation

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ISIJ International 2025年第5期65卷 695-703页

作者： Yamamura, Ayano Yasuda, Hideyuki Takaki, Tomohiro Graduate School of Science and Technology Kyoto Institute of Technology Matsugasaki Sakyo-ku Kyoto606-8585 Japan Department of Materials Science and Engineering Kyoto University Yoshidahonmachi Sakyo-ku Kyoto606-8501 Japan Faculty of Mechanical Engineering Kyoto Institute of Technology Matsugasaki Sakyo-ku Kyoto606-8585 Japan

The solid–liquid interface energy anisotropy of Zn alloys remains poorly understood. Recently, characteristic 14-arm dendritic growth has been observed using time-resolved X-ray computed tomography at SPring-8 during the solidification of a Zn-4mass%Al alloy. This study investigates the dependence of the dendrite morphologies of Zn alloys on solid–liquid interface energy anisotropy through systematic phase-field simulations of the growth of an isolated equiaxed dendrite. We also develop a data assimilation system to estimate the anisotropy parameters of solid–liquid interface energy and crystal orientation in Zn alloys and validate the system through twin experiments. This study provides insights into the solidification of Zn alloys and a powerful tool for their investigation. © 2025 The Iron and Steel Institute of Japan.

关键词： Aluminum alloys

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Innovating Blended Learning Model for Professional Education in Manufacturing 19th

Innovating Blended Learning Model for Professional Education...

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19th Global Conference on Sustainable Manufacturing, GCSM 2023

作者： Krajnik, Peter Hoier, Philipp Laakso, Sampsa Department of Industrial and Materials Science Chalmers University of Technology Gothenburg412 96 Sweden Department of Mechanical and Materials Engineering Faculty of Technology University of Turku Joukahaisenkatu 3 Turku20520 Finland

ISBN: (纸本)9783031774287

Advancements in technology and the increasing prevalence of digitalization in industry require a new approach to professional education. The primary objective is to enhance the skills of working professionals, ensure content is relevant to industry needs, increase learner engagement, and optimize learner and instructor efficiency. To achieve these goals, a new methodology is proposed, utilizing constructive alignment, outcome-based education, and blended learning strategies. This approach incorporates asynchronous digital learning, synchronous online lectures, and interactive debriefing sessions, providing an engaging blend of self-paced learning and active, instructor-led experiences. Evaluation results show an improved course structure and a positive learning experience, despite initial implementation challenges. While not exclusively designed for sustainable manufacturing education, this approach offers innovative learning pathways and has the flexibility to integrate specific modules, such as those related to sustainability. Based on evaluation feedback and measurable learner outcomes, ongoing refinements to this model suggest a promising shift in the approach to professional education within the manufacturing sector. © The Author(s) 2025.

关键词： Smart manufacturing

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