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5th International Conference on Optoelectronic science and materials, ICOSM 2023

作者： Zhang, Hao Xing, Yulong Gao, Lilan Liu, Zheng Tan, Yansong Lu, Guoquan Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin300384 China National Demonstration Center or Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China Tianjin Yixunyuan New Material Technology Co. Ltd. Tianjin300380 China School of Chemical Engineering Tianjin University Tianjin300350 China School of Materials Science and Engineering Virginia Polytechnic Institute and State University BlacksburgVA24061 United States

ISBN: (纸本)9781510674547

As mobile technology evolves from 5G to 6G, the demand for third-generation semiconductors such as SiC with higher power and frequency capabilities is increasing. Silicon Carbide power modules generate significant heat during operation, requiring large-area nano-silver sintering technology to improve module performance and reliability. However, in large-area sintering processes, low exhaust efficiency of solder paste by-products and uneven sintering pressure of the nano-silver paste result in poor sintering quality of the silver layer. This study aims to improve the sintering quality of interconnected silver layers by optimizing the sintering pressure distribution and adding rubber spacers to the sintering structure. ABAQUS was used to quantitatively analyze the effects of pressure methods and gasket material, diameter, and thickness on the stress distribution in the silver layer. Finally, based on the simulation results, an optimized sintering structure was proposed to unify the pressure and reduce the stress concentration in the silver layer, and verified experimentally by sintering tests. Compared with the traditional sintering structure, the application of a 2 mm thick fluoro rubber gasket with the same surface area as the silver layer in the optimized structure reduced the porosity to 2.15% and achieved a more dense sintered silver layer. © 2024 SPIE.

关键词： Finite element method

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Grain-Level Mechanism of Plastic Deformation in Harmonic Structure materials Revealed by High-Resolution X-Ray Diffraction

SSRN

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SSRN 2023年

作者： Sjögren-Levin, Elis Pantleon, Wolfgang Hegedüs, Zoltan Lienert, Ulrich Ahadi, Aylin Tsuji, Nobuhiro Ameyama, Kei Orlov, Dmytro Department of Mechanical Engineering Sciences Division of Mechanics Materials and Components LTH Lund University Box 118 Lund22100 Sweden Department of Civil and Mechanical Engineering Section of Materials and Surface Engineering Technical University of Denmark Kongens Lyngby2800 Denmark Hamburg22607 Germany Department of Materials Science and Engineering Kyoto University Yoshida-honmachi Sakyo-ku Kyoto606-8501 Japan Department of Mechanical Engineering Faculty of Science and Engineering Ritsumeikan University 1-1-1 Nojihigashi Kusatsu Shiga525-8577 Japan

materials with heterogenous microstructures have been reported to have an attractive combination of strength and ductility. This is attributed to synergistic strengthening effects from the difference in strength of fine- and coarse-grained regions. Understanding the interaction of the regions is crucial for further optimization of the microstructures. In this work, we fabricated nickel of harmonic structure (HS) and a reference with homogenous coarse grains. The HS constitutes of an interconnected fine-grained network that surrounds regions of coarse grains. The interplay of the regions was studied by monitoring Bragg reflections from individual grains in situ during tensile deformation until approximately 2% strain through synchrotron X-ray diffraction. The technique allows grain-level assessment of the degree of plastic deformation. Two grains were followed in the reference and two small grains (fine-grained region) and two large grains (coarse-grained region) in the HS. Three deformation regimes were identified: elastic deformation, onset of plastic deformation and significant plastic deformation. Our results reveal that the large grains in the harmonic structure onset plastic deformation during the macroscopic elastic stage. With increasing applied stress, the small grains also make the switch and once a large fraction of the fine-grained network deforms plastically the large grains switch to significant plastic deformation. Notably, the onset of significant plastic deformation of large grains in the HS occurs at approximately 100 MPa higher applied stress than in the grains in the reference. This shows that fine grains constrain the large grains from deforming plastically in the HS. © 2023, The Authors. All rights reserved.

关键词： Plastic deformation

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The Effect of Fsw Parameters on the Macro/Micro-Galvanic Corrosion of the Dissimilar Joint between Az31 and Aa5052

SSRN

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SSRN 2023年

作者： Safari, Saeed Nouripour, MohammadHossain Ghorbani, Mohammad Safari, Hossein Department of Materials Science and Engineering Sharif University of Technology Tehran Iran Department of Mechanical Engineering Islamic Azad University West Tehran Branch Tehran Iran

In this study, dissimilar friction stir welding was performed between AA5052 aluminium and AZ31 magnesium alloys using a variety of parameters. The results revealed that the optimal range of welding parameter is between 20 to 38 rpm/***-1 (the ratio of rotation speed to travel speed). The findings of the X-ray diffraction and micro-hardness tests on the stir zone indicated that when the rotation speed is increased, it leads to the formation of intermetallic compounds such as Al12Mg17 and Al3Mg2. The polarization test was used to evaluate the corrosion rate in various zones. The corrosion resistance in the stir zone is less than in other zones due to macro-galvanic couple between Al and Mg. Additionally, the corrosion rate in the stir zone of sample welded at highest rotation speed of 750 rpm is 1.6 ***-2, which is nearly 2.24 times higher than the corrosion rate in other samples. That is attributed to the micro-galvanic coupling of intermetallic compounds (cathode) to the matrix (anode), as well as the macro-galvanic coupling of AA5052 aluminium to AZ31 magnesium alloys. © 2023, The Authors. All rights reserved.

关键词： Intermetallics

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Phase-based analysis and control of supersonic turbulent cavity flows

arXiv

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arXiv 2025年

作者： Godavarthi, Vedasri Kawamura, Yoji Ukeiley, Lawrence S. Cattafesta, Louis N. Taira, Kunihiko Department of Mechanical and Aerospace Engineering University of California Los AngelesCA90095 United States Center for Mathematical Science and Advanced Technology Japan Agency for Marine-Earth Science and Technology Yokohama236-0001 Japan Department of Mechanical and Aerospace Engineering University of Florida GainesvilleFL32611 United States Department of Mechanical Materials and Aerospace Engineering Illinois Institute of Technology ChicagoIL60616 United States

We present a phase-based framework for reducing the pressure fluctuations within a spanwise-periodic supersonic turbulent cavity flow with an incoming free-stream Mach number of 1.4 and a depth-based Reynolds number of 104. Open cavity flows exhibit large fluctuations due to the feedback between the shear layer instabilities and the acoustic field. The dominant flow physics includes the formation, convection, and impingement of large-scale spanwise-oriented vortical structures. We formulate a flow control strategy to effectively modify the vortex convection frequency, thereby disrupting the feedback loop and suppressing pressure fluctuations within the cavity. We implement a phase-reduction approach to identify the flow response about the time-varying convective process by defining a phase variable using dynamic mode decomposition. Three-dimensional impulse perturbations are introduced from the cavity leading edge to characterize phase response in terms of advancement or delay of convection. We perform open-loop flow control through unsteady blowing using actuation frequencies slightly different from the vortex convection frequency to disrupt the feedback loop. After designing a phase-sensitivity-based actuation waveform optimized for quick flow modification, we investigate the speed of fluctuation reduction and compare it to a sinusoidal waveform. At a spanwise actuation wavenumber of β = 2π, both perform similarly, achieving a 46% reduction of pressure fluctuations within five convective times. At β = π, the phase-sensitivity-based actuation performs better by achieving a 40% reduction compared to the 30% with a sinusoidal waveform within six convective times. This study shows the potential of phase-based analysis for timing-based flow control of unsteady turbulent flows. © 2025, CC BY.

关键词： Vortex flow

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Manufacturing of Cu-10sn/Sic/Mica Hybrid Composite Using Powder Metallurgy Process and Optimizing of Corrosion Resistance

SSRN

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SSRN 2023年

作者： Mehrabad, Vahid Zakeri Doniavi, Ali Arghavanian, Reza Kavanlouei, Majid Department of Mechanical Engineering Faculty of Engineering Urmia University Urmia Iran Department of Manufacturing Engineering Tabriz Branch Islamic Azad University Tabriz Iran Department of Materials Science and Engineering Faculty of Engineering Urmia University Urmia Iran

In this work, for the first time, bronze/SiC/mica hybrid composite has been manufactured using powder metallurgy method. Mixture - process variable design has been applied to design of experiments and optimization of the composite composition and production process variables (pressing pressure and sintering temperature) to achieve the highest corrosion resistance. For this, various compositions of bronze, SiC and mica powders were mixed then pressed and sintered at different pressures and temperatures according to the plan of experiments design. SEM, EDX and optical microscope have been used to investigate the microstructure, chemical composition and particles distribution of the samples. In order to study the corrosion resistance, potentiodynamic polarization test and EIS have been performed in 3.5 wt.% NaCl solution. The results revealed that co-incorporation of SiC and mica particles in Cu-10Sn bronze matrix increases the corrosion resistance and these particles intensify each other’s effect. The result of optimization showed that the composite with the composition of Cu-10Sn/9.85SiC/0.67mica could have the highest corrosion resistance which has been confirmed by experimental procedure. © 2023, The Authors. All rights reserved.

关键词： Corrosion resistance

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Fabrication of covalently modified graphene oxide-based assembled polymer brushes as efficient aqueous lubricant additive

引用

Journal of Molecular Liquids 2024年 416卷

作者： Samanta, Suprakash Yoon, Dang-Hyok Sahoo, Rashmi R. School of Materials Science and Engineering Yeungnam University 38541 Cuba School of Applied Sciences and Humanities Haldia Institute of Technology West Bengal Haldia721657 India Coatings & Surface Engineering Group CSIR - Central Mechanical Engineering Research Institute Durgapur713209 India Ghaziabad201002 India

The present study demonstrates a facile and multistep chemical approach for preparing covalent functionalized graphene oxide (GO) followed by the layer-by-layer assembly of polymer brushes on functionalized GO for aqueous lubricants. Simultaneous reduction and surface modification of GO with 6-amino-4-hydroxy-2-naphthalenesulfonic acid (ANS) and polyethylenimine (PEI) was performed to synthesize functionalized GO (rGO-ANS and rGO-PEI) through a nucleophilic addition reaction pathway to enhance the thermal and dispersion stability in water. Polymer brush particles were fabricated on modified rGO-PEI using anionic polyelectrolytes to extend the load-bearing ability under water-lubricated conditions. The chemical, structural, wettability, and morphological features of functionalized GO and polymer brush particles were well characterized using standard spectroscopic and microscopic techniques. The macrotribological results showed that rGO-ANS (0.5 wt%) exhibited a steady coefficient of friction (COF) with increasing load-bearing ability up to 500 N load (Pm ∼ 4.8 GPa) compared to GO. Although the ANS chains helped to generate an antifrictional tribofilms, the smeared particle film was unable to decrease the COF and wear with increasing the contact pressure to a lower level. Whereas, the poly(sodium 4-styrenesulfonate) (PSS) containing polymer brush (rGO-PBS) showed a significant reduction of the COF (∼ 61.5 %) and wear volume (∼ 82.9 %) at a 147 N load compared to the GO under water lubricated conditions. rGO-PBS also exhibited higher load-bearing capacity up to 800 N load (Pm ∼ 5.8 GPa) with a significantly lower COF and wear among particles. The sulfonate groups containing PSS in rGO-PBS provided robust interfacial adhesive properties to the steel tribo pairs, which facilitated the formation of antifrictional protective tribofilm through well-hydrated polymeric cushioning layers to reduce the COF, wear, and enhance the load-affording ability. Therefore, the excellent

关键词： Addition reactions

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Modeling and Ignition Performance Study of Al/Ni Multilayer Energy-Containing Microdevices

SSRN

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SSRN 2023年

作者： Yan, Shaoan Zang, Junyi Zhu, Yingfang Tang, Tao Chen, Xin Li, Xingyu Chen, Yinyu Zheng, Xuejun Tang, Minghua School of Mechanical Engineering and Mechanics Xiangtan University Hunan Xiangtan411105 China School of Materials Science and Engineering Xiangtan University Hunan Xiangtan411105 China

In this paper, we designed double V-shaped Al/Ni multilayer energy-containing microdevices with different V-angles, and performed finite element modeling and simulation of the heat transfer process of the designed energy-containing microdevice, temperature-dependent resistivity was introduced to effectively simulate the phase change during ignition. We simulated the temperature and current density distribution in the central region of the Al/Ni multilayer energy-containing microdevice and predicted the ignition voltage threshold for the specific device structure. The Al/Ni multilayer energy-containing microdevices with different V-angles were prepared by electron beam evaporation technology, and the ignition experiments on the prepared devices under the excitation of 47 μF capacitance were conducted. The experimental results show that the critical voltage of ignition increases with the increase of V-angle, which verifies the correctness of the proposed finite element model. © 2023, The Authors. All rights reserved.

关键词： Capacitance

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Pseudobrookite based heterostructures for efficient electrocatalytic hydrogen evolution

引用

materials Reports(Energy) 2021年第2期1卷 90-98页

作者： Niranjala Fernando Jayashree Swaminathan Francisco Carlos Robles Hernandez Gayan Priyadarshana Chanaka Sandaruwan Wenli Yang Veranja Karunaratne Zixing Wang Gehan AJAmaratunga Nilwala Kottegoda Ashokkumar Meiyazhagan Pulickel M.Ajayan Department of Design and Engineering Faculty of Science and TechnologyBournemouth UniversityDorsetBH125BBUK Department of Materials Science&NanoEngineering Rice UniversityTexas77005USA Department of Mechanical Engineering Technology University of HoustonHoustonTX77204USA Materials Science&Engineering Cullen College of EngineeringUniversity of HoustonHoustonTX77204USA Department of Materials and Mechanical Technology Faculty of TechnologyUniversity of Sri JayewardenepuraPitipanaHomagamaSri Lanka Sri Lanka Institute of Nanotechnology PitipanaHomagamaSri Lanka Department of Engineering University of CambridgeCambridgeCB21TNUK Department of Chemistry Center for Advanced Materials ResearchUniversity of Sri JayewardenepuraGangodawilaNugegodaSri Lanka

Synthesis of ultrathin heterostructures has received much attention in the recent past due to their unique physical and chemical *** this work,we report the synthesis of Fe_(2)TiO_(5)–TiO_(2)heterostructures using a simple hydrothermal technique employing natural ilmenite as the *** arranged nanostructures with interconnected nano-petals of thickness around 50 nm are *** electrocatalytic properties of the synthesized Fe_(2)TiO_(5)–TiO_(2)heterostructures are enhanced following the cathodization *** observed enhancement in the synthesized materials’electrocatalytic property can be attributed to the defect-rich Fe_(2-x)TiO_(5-x)-TiO_(2-x)*** current approach and technique discussed in this work offer a simple method to synthesize a nanostructured heterostructure material and create defects for enhancing electrocatalytic activity.

关键词： Heterostructures Cathodization Green catalyst 2D materials Hydrogen evolution Electrocatalysis Pseudobrookite

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Robust Attitude Control of Multibody Aircraft with Preview-Based Control Compensation 6th

Robust Attitude Control of Multibody Aircraft with Preview...

引用

6th China Aeronautical science and Technology Conference, CASTC 2023

作者： Qi, Pengyuan Li, Qingxian Mou, Quanrun Wang, Yinan Research Institute for Frontier Science Beihang University Beijing100191 China School of Automation Science and Electrical Engineering Beihang University Beijing100191 China Large Aircraft Advanced Training Center Beihang University Beijing100191 China Department of Mechanical Materials and Aerospace University of Liverpool LiverpoolL69 3BX United Kingdom

ISBN: (纸本)9789819988662

This paper investigates the robust attitude control for wingtip-connected multibody aircraft, using preview-based control compensation mechanism to address the issues of inherent wingtip couplings. A constrained multibody dynamics model is first derived to obtain the nonlinear and linearised formulations for multibody aircraft. The H∞ control is employed to synthesize the pitch angle and forward velocity controller in the longitudinal channel, while the H∞ preview control is employed to synthesize the roll angle and yaw rate controller in the lateral channel. The preview control scheme enables the usage of future reference commands as feedforward information to synthesize appropriate control compensation to reduce the impact of wingtip couplings between adjacent aircraft units. Simulation studies conducted based on the nonlinear model show that the preview-based H∞ control system is able to achieve better control effectiveness and disturbance rejection performance, compared to the baseline regular H∞ control system without preview. These demonstrate that the mechanism of control compensation can greatly benefit the flight control of multibody aircraft. © 2024, Chinese Society of Aeronautics and Astronautics.

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Synthesis, Characterisation, and Corrosion Inhibition Performance of a β-Cyclodextrin/Melamine Supramolecular Complex on St20 Steel in Acidic Media

引用

Journal of Bio- and Tribo-Corrosion 2024年第4期10卷 1-22页

作者： Berdimurodov, Elyor Eliboev, Ilyos Dagdag, Omar Lal, Basant Berisha, Avni Rajabov, Yusufboy Mamatov, Jaykhun Wan Nik, W.B. Kholikov, Abduvali Akbarov, Khamdam Chemical & amp Materials Engineering New Uzbekistan University 54 Mustaqillik Ave. Tashkent100007 Uzbekistan Faculty of Chemistry National University of Uzbekistan Tashkent100034 Uzbekistan Uzbek-Finnish Pedagogical Institute Spitamen Street 166-Home Samarqand Uzbekistan Department of Mechanical Engineering Gachon University Seongnam13120 Korea Republic of Department of Chemistry Institute of Applied Science and Humanities GLA University Mathura281406 India Department of Chemistry Faculty of Natural and Mathematics Science University of Prishtina Prishtina10000 Albania Faculty of Ocean Engineering Technology and Informatics Universiti Malaysia Terengganu Kuala Nerus21030 Malaysia Physics and Chemistry "Tashkent Institute of Irrigation and Agricultural Mechanization Engineers" National Research University Tashkent100000 Uzbekistan Natural Science University of Tashkent for Applied Sciences Str. Gavhar 1 Tashkent100149 Uzbekistan Physics and Chemistry Western Caspian University BakuAZ-1001 Azerbaijan

Corrosion poses major challenges in various industrial sectors such as oil and gas, chemicals, and infrastructure. Traditional corrosion inhibitors have limitations in terms of toxicity and environmental compatibility. Supramolecular complexes are promising as green corrosion inhibitors, as the interaction between host and guest molecules can be tailored for different application needs. This study investigates a β-cyclodextrin (β-CD)/melamine (ME) supramolecular complex. The synthesis of the complex is confirmed by Raman spectroscopy, 1H NMR, and FT-IR methods. A range of characterisation techniques are used to analyse the complex’s structure. Gravimetric and electrochemical tests, including potentiodynamic polarisation and electrochemical impedance spectroscopy, evaluate its corrosion inhibition performance on steel in 0.5 M HCl solution at varying concentrations (25–100 mg/L) and temperatures (303 to 333 K). Computational modelling, including Density Functional Theory, Monte Carlo, and Molecular Dynamics simulations, provides atomic-scale insights into the mechanisms of inhibition. The synthesis, characterisation, and corrosion prevention performance of a novel supramolecular complex, β-cyclodextrin/melamine (β-CD/ME), on St20 steel, in acidic conditions, were the subjects of an inventive investigation that was described in this publication. The complex’s structural alterations, physical interactions, and structure were effectively disclosed, using Raman spectroscopy, 1H NMR, and FT-IR. The β-CD/ME complex’s ability to prevent corrosion in hostile solutions exceeded 92–94%, resulting in the formation of a thin protective film on the metal surface and acting as a mixed-type inhibitor. A novel mix of theoretical and experimental methods is used in this work to comprehend the underlying mechanisms, including the influence of structural factors on corrosion prevention effectiveness and the adsorption energies of the complex on the metal surface. Electrochemical tests

关键词： Molecular dynamics

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