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Creep-recovery deformation of 304 stainless-steel springs under low forces

Mechanics of materials 2024年 193卷

作者： Tsai, Ming-Yen Chang, Shou-Yi Zhang, Yulin Yang, Fuqian Lee, Sanboh Department of Materials Science and Engineering National Tsing Hua University Hsinchu300 Taiwan Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing400714 China Materials Program Department of Chemical and Materials Engineering University of Kentucky LexingtonKY40506 United States

The deformation behavior of materials at high temperatures determines the structural stability of mechanical structures under high-temperature service conditions. In this work, we prepare helical springs from 304 stainless-steel wires and study creep-recovery deformation of the helical springs under small forces at temperatures of 475–575 °C. In contrast to most methods reported in the literature, we use Kelvin representation of the Burgers model with a nonlinear dashpot in series connection to analyze the creep-recovery deformation of the helical springs and suggest the deformation mechanisms of the diffusion of interstitial atoms and dislocation generation/annihilation in transient creep and recovery of the helical springs under small forces. For the creep deformation, the stress exponent and activation energy for the plastic flow of the nonlinear dashpot are 2 and 57.8 kJ/mol, respectively, and the activation energy for the deformation flow of the linear dashpot is 41.8 kJ/mol. The nonlinear dashpot does not play any role in the recovery deformation, and the formation energy of defects for the recovery deformation of the helical springs is 51.4 kJ/mol. The approach used in this work provides a simple method to use a phenomenological model with a nonlinear dashpot to capture the power-law creep deformation of metallic materials. © 2024

关键词： Activation energy

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Impact of Electrical Current Stressing on ?'-Cu6Sn5 in Electronics Packaging 19

Impact of Electrical Current Stressing on ?'-Cu6Sn5 in Elect...

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19th International Microsystems, Packaging, Assembly and Circuits Technology Conference, IMPACT 2024

作者： Mukherjee, Shubhayan Lin, Shih-Kang National Cheng Kung University Department of Materials Science and Engineering Tainan70101 Taiwan Research Center Tainan70101 Taiwan Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Program on Smart and Sustainable Manufacturing Tainan70101 Taiwan

ISBN: (纸本)9798331532246

In advanced electronic packaging, the stability of intermetallic compounds (IMCs) under high electric current density is crucial for the reliability of solder joints. Cu6Sn5, a predominant IMC formed between Sn-based solders and Cu substrates, exists in two allotropes: the high-temperature hexagonal phase and the low-temperature monoclinic ?' phase, with a transition temperature of 186°C. This study investigates the effects of electric current on ?'-Cu6Sn5 phase, focusing on structural characterization and mechanical properties. Various electric current densities were applied to thermally aged ?'-Cu6Sn5. Synchrotron radiation-based X-ray diffraction (SR-XRD) was used to examine crystallographic changes, while nanoindentation tests assessed mechanical property alterations. These observations contribute to understanding the impact of electric current density on the structural and mechanical behavior of the monoclinic ?'-Cu6Sn5 phase. © 2024 IEEE.

关键词： Synchrotron radiation

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An Investigation of Cu/Ni/Ga Interfacial Reaction with Different Ni/Ga Ratio 23

An Investigation of Cu/Ni/Ga Interfacial Reaction with Diffe...

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23rd International Conference on Electronics Packaging, ICEP 2024

作者： Huang, Tzu-Hsuan Huang, Jian-Wei Lin, Zhih-Feng Lin, Shih-Kang National Cheng Kung University Department Of Materials Science And Engineering Tainan70101 Taiwan Research Center Tainan70101 Taiwan National Cheng Kung University Program On Smart And Sustainable Manufacturing Academy Of Innovative Semiconductor And Sustainable Manufacturing Tainan70101 Taiwan

ISBN: (纸本)9784991191176

In this article, we utilized electroplating method forming Cu/Ni/Ga structure. Interfacial reaction was investigated with different ratio of Ni: Ga 7:3 and 1:20. The result showed that Ga reacted with the substrates immediately as plated forming NiGas and CuGa2 compound respectively in different ratio of Ni: Ga. IMCs transformed into Ni2Ga3and Cu31.3Ga16.3 respectively after 300°C heat treatment. This research explored a new optimizing idea in developing Ga TLP bonding technology. © 2024 Japan Institute of Electronics Packaging.

关键词： Electroplating

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Controllable morphology and enhanced luminescence in hydrothermally Cr3+-Doped Na3GaF6 phosphors for NIR imaging

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Ceramics International 2025年

作者： Xiao, Yiren Pan, Xin Su, Ke Wu, Zhaojie Wang, Yujia Zhang, Guangqing Jian, Yuanhao Mei, Lefu Liao, Libing Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes National Laboratory of Mineral Materials School of Materials Science and Technology China University of Geosciences Beijing100083 China Department of Materials Science and Engineering Southern University of Science and Technology Shenzhen518055 China College of Materials and Fujian Key Laboratory of Surface and Interface Engineering for High Performance Materials Xiamen University Xiamen361005 China School of Science China University of Geosciences Beijing100083 China

Cr-doped fluorides are promising for near-infrared (NIR) imaging due to their broad emission spectra and tunable luminescence within low-phonon-energy matrices. However, achieving precise control over particle morphology to enhance luminescence remains challenging. This study employs hydrothermal synthesis to optimize the morphology and NIR emission of Cr3+-doped Na3GaF6 phosphors by varying synthesis parameters like temperature and surfactant type. Optimized conditions produced larger, uniform polyhedral particles that exhibited enhanced NIR emission (650–900 nm), peaking at 756 nm under 431 nm excitation. When used in a NIR phosphor-converted LED (NIR-pc-LED), the phosphors achieved a radiation flux of 28.88 mW at 320 mA and a photoelectric conversion efficiency of 2.73%, showcasing their potential for NIR imaging applications such as biological imaging and night vision technologies. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Infrared imaging

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Comparison of Coherent and Incoherent Donut Beams for Deep Tissue STED Microscopy

Comparison of Coherent and Incoherent Donut Beams for Deep T...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Shanavas, Thariq McLeod, Robert R. Siemens, Mark E. Gopinath, Juliet T. Department of Physics University of Colorado BoulderCO80309 United States Department of Electrical Computer and Energy Engineering University of Colorado BoulderCO80309 United States Department of Physics University of Denver DenverCO80204 United States Materials Science Engineering Program University of Colorado BoulderCO80309 United States

We numerically compare the null quality for STED microscopy generated by Laguerre-Gaussian beams with orbital angular momentum and donut beams generated by incoherent addition of orthogonal Hermite Gaussian beams when... 详细信息

ISBN: (纸本)9781957171258

关键词： Tissue

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Accuracy of DFT computed oxygen-vacancy formation energies and high-throughput search of solar thermochemical water-splitting compounds

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Physical Review materials 2023年第6期7卷 065403-065403页

作者： Bianca Baldassarri Jiangang He Xin Qian Emanuela Mastronardo Sean Griesemer Sossina M. Haile Christopher Wolverton Graduate Program in Applied Physics Northwestern University Evanston Illinois USA Department of Materials Science and Engineering Northwestern University Evanston Illinois USA

The enthalpy change involved in metal oxide reduction is a key quantity in various processes related to energy conversion and storage and is of particular interest for computational prediction. Often this prediction involves the simulation of a high-temperature reduction process with a 0-K methodology like density functional theory (DFT), and it is not infrequent for the high temperature and 0-K stable crystal structures to differ. This introduces a conundrum with regard to the choice of crystal structure to utilize in the computation, with approaches in the literature varying and experimental validation remaining scarce. In this work, we address both the crystal structure conundrum and the experimental validation, and then apply the insights we gain to guide a high-throughput search for new materials for solar thermochemical water-splitting applications. By computing the DFT+U oxygen-vacancy formation energy (ΔEvf) of a selection of ABO3 compounds and comparing different crystal structures for each composition, we highlight the issues that arise when the structure utilized in the computation is dynamically unstable at 0 K, namely the presence of an artificial lowering of ΔEvf, and the lack of convergence of ΔEvf with cell size. We solve these limitations by identifying and employing a suitable surrogate dynamically stable structure. We then validate the predictive power of our calculations against appositely generated experimental measurements of reduction enthalpy for a series of Hubbard U values, finding an accuracy ranging between 0.2–0.6 eV/O. In light of such conclusions, we revise and expand a previous a high-throughput DFT study on ABO3 perovskite oxides. We provide a list of candidate STCH materials, highlight trends with redox-active cation and structural distortion, and identify Mn4+, Mn3+, and Co3+ as the most promising redox-active cations.

关键词： Energy applications First-principles calculations Hydrogen energy

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Design and optimization of a fluid flow splitting device for low-flow applications

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SLAS Technology 2025年 32卷 100305页

作者： Yates, Alexis K. Murray, Heather N. Lippmann, Ethan S. Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN United States Chemical and Biomolecular Engineering Department Vanderbilt University NashvilleTN United States

Microfluidic devices are defined by the application of fluid flow to micron-scale features. Inherent to most experiments involving microfluidic devices is the need to precisely and reproducibly control fluid flow at the microliter scale, often through multiple inlet ports on a single device. While the number of fluid channels per device varies, perfusing multiple inputs requires either the use of multiple flow controllers (often syringe or peristaltic pumps) or the ability to evenly divide fluid across outlets. Towards the latter approach, while a handful of commercial systems exist for splitting fluid flow, these set-ups require significant financial investment, multiple flow control and sensing components, and restrict the user to a predetermined perfusion control system. Simple in-line splitting devices, such a manifolds or T junctions, fail to achieve flow splitting at low flow rates often used in microfluidic systems. To increase capabilities for flow-controlled experiments, we performed experimental analyses of the physical considerations governing even flow splitting under low flow, leading to the design of a microdevice (µ-Split) that can be directly inserted into existing microfluidic set-ups. The µ-Split allows for reproducible, even flow splitting from 10 uL/min to > 2.5 mL/min. By testing multiple device geometries in combination with multiphysics simulations, we identified the design and fabrication features underlying the splitting precision achieved by the µ-Split. Overall, this work provides a useful tool to simplify microfluidic experiments that require evenly divided flow streams, while minimizing the overall device footprint. © 2025

关键词： Microfluidics

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Thermodynamic and Environmental Assessment of Low-GWP Alternative Refrigerants for Domestic Cooling

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Journal of The Institution of Engineers (India): Series C 2023年第2期104卷 377-383页

作者： Islam, Md. Amirul Rupam, Tahmid Hasan Hosan, Shahadat Saha, Bidyut Baran Institute for Materials Chemistry and Engineering Kyushu University Kasuga-Koen 6-1 Kasuga-Shi Fukuoka816-8580 Japan Department of Electrical and Electronics Engineering Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj8100 Bangladesh Kyushu University 744 Motooka Nishi-Ku Fukuoka819-0395 Japan Kyushu University Program for Leading Graduate School Green Asia Education Center Kyushu University Fukuoka Japan Department of Mechanical Engineering Kyushu University 744 Motooka Nishi-Ku Fukuoka819-0395 Japan

Nearly two billion air-conditioning (AC) units are currently being used for space cooling worldwide. The majority of these ACs use R134a as the working fluid, a greenhouse gas (GHG) with a global warming potential (GWP) of 1300 kg-CO2-eq. According to the rules set by the world environment safety organizations, the GWP of domestic air-conditioning systems must not exceed 750 kg-CO2-eq. Hence, the R134a must be phased out by 2025, and an alternative refrigerant with similar thermodynamic properties yet low GWP is required. Therefore, the authors have investigated several potential binary/ternary refrigerant blends in this study. Among the studied refrigerants, R445A, R30A, and NPB2 (newly proposed blend: 8% R152a + 92% R1234yf) can reduce 90–99% global warming impact (more than 200 million tonnes of CO2 emission equivalent) caused by the domestic air-conditioning systems every year. © 2023, The Institution of Engineers (India).

关键词： Refrigerants

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Flexible organic solar cells for biomedical devices

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Nano Research 2021年第9期14卷 2891-2903页

作者： Bin Kan Faheem Ershad Zhoulyu Rao Cunjiang Yu Department of Mechanical Engineering University of HoustonHoustonTX 77204USA Department of Biomedical Engineering University of HoustonHoustonTX 77204USA Materials Science and Engineering Program University of HoustonHoustonTX 77204USA Department of Electrical and Computer Engineering University of HoustonHoustonTX 77204USA Texas Center for Superconductivity University of HoustonHoustonTX 77204USA

Organic solar cells(OSCs),particularly made based on solution processing methods,have made significant progress over the past decades through the concurrent evolution of organic photovoltaic materials and device ***,high power conversion efficiencies around 18%and over 16%have been demonstrated in both rigid and flexible OSCs,*** most of the OSC research has centered on efficiency and cost,their emerging and potential usages in many critical applications,particularly in biomedical fields have been *** this mini-review,we will briefly discuss the high-performance organic photovoltaic materials and the representative flexible OSCs to give a scope on the recent rapid development of ***,we will review some progress on the applications of OSCs in biomedical devices and integrated *** potential challenges associated with integrating OSCs for biomedical devices will be put forward.

关键词： organic solar cells photovoltaic flexible biomedical bioelectronics

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Atomistic modeling and rational design of optothermal tweezers for targeted applications

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Nano Research 2021年第1期14卷 295-303页

作者： Hongru Ding Pavana Siddhartha Kollipara Linhan Lin Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA

Optical manipulation of micro/nanoscale objects is of importance in life sciences,colloidal science,and *** tweezers exhibit superior manipulation capability at low optical ***,our implicit understanding of the working mechanism has limited the further applications and innovations of optothermal ***,we present an atomistic view of opto-thermo-electro-mechanic coupling in optothermal tweezers,which enables us to rationally design the tweezers for optimum performance in targeted ***,we have revealed that the non-uniform temperature distribution induces water polarization and charge separation,which creates the thermoelectric field dominating the optothermal *** further design experiments to systematically verify our atomistic *** by our new model,we develop new types of optothermal tweezers of high performance using low-concentrated ***,we demonstrate the use of new tweezers in opto-thermophoretic separation of colloidal particles of the same size based on the difference in their surface charge,which has been challenging for conventional optical *** the atomistic understanding that enables the performance optimization and function expansion,optothermal tweezers will further their impacts.

关键词： optothermal tweezers optical tweezers optical manipulation thermophoresis molecular dynamics simulation

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