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The microstructure evolution and deformation mechanism in a casting AM80 magnesium alloy under ultra-high strain rate loading

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Journal of Magnesium and Alloys 2022年第11期10卷 3205-3216页

作者： Pengcheng Guo Xiao Liu Biwu Zhu Wenhui Liu Liqiang Zhang School of Mechanical and Electrical Engineering Central South University of Forestry and TechnologyChangsha 410004China School of Material Science and Engineering Hunan University of Science and TechnologyXiangtanHunan 411201China

Ultra-high strain rate impact tests were conducted by Split-Hopkinson pressure bar to investigate the microstructure evolution and impact deformation mechanism of a solution treated casting AM80 Mg alloy at 25, 150 and 250 ℃ with a strain rate of 5000 s^(-1). The microcrack and dynamic recrystallization(DRX) preferentially nucleate at grain boundary(GB) and twin boundary(TB), especially at the intersections between GBs and TBs, and then propagate along twin direction. In contrast, the adiabatic shear bands preferentially occur at high-density twined regions. At 25 ℃, the dominated deformation mechanisms are basal slip and twinning. As deformation temperature increases to 150and 250℃, the deformation gradually shifts to be dominated by a coordinated mechanism among non-basal slip, twinning and DRX. The flow stress behavior and deformation mechanism indicate that the degree of decrease in flow stress with temperature is associated with the change of deformation mode.

关键词： AM80 mg alloy Deformation mechanism Ultra-high strain rate Twinning Dynamic recrystallization

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Advancing sustainable casting through cryogenic gradient forming of frozen sand molds:Design,error control,and experimental validation

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Journal of materials science & Technology 2024年第36期203卷 211-226页

作者： Jianpei Shi Zhongde Shan Haoqin Yang Shijie Dong Qinjiang Liu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China

Owing to its exceptional casting performance,substantial utilization of recycled sand,and environmen-tally sustainable characteristics,frozen sand mold casting technology has found extensive application across diverse sectors,including aerospace,power machinery,and the automotive *** focus of the present study was on the development of frozen sand mold formulations tailored for efficient machin-ing,guided by the performance and cutting fracture mechanism of frozen sand molds.A regional tem-perature control device was developed for the purpose of conducting cryogenic cutting experiments on frozen sand molds with varying geometrical characteristics and molding *** impact of milling process parameters on the dimension accuracy of both sand molds and castings,as well as castings’surface roughness,were systematically investigated by a whole-process error flow control *** findings indicate that precise and efficient processing of complicated sand molds was achievable by using sand particles with sizes ranging from 106 to 212μm,and water content between 4 and 5 wt.%,freezing temperature below-25℃,and cutting temperature within the range of-5 to 0℃.Through the frozen-casting of representative components,it was validated that the machining error of the frozen sand mold was within±0.25 ***,the dimensional accuracy of the flywheel shell casting conformed to the CT8 *** study provides theoretical guidance for the selection of frozen-casting sand formulations and close-loop control of process size chains for complex metal parts,as well as an overall solution for the realization of sustainable development of green casting.

关键词： Frozen sand mold Cryogenic machining Dimensional accuracy Surface roughness Green casting

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The prospects of natural fiber composites: A brief review

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International Journal of Lightweight materials and Manufacture 2024年第4期7卷 496-506页

作者： Palanisamy, Sivasubramanian Vijayananth, Kavimani Murugesan, Thulasi Mani Palaniappan, Murugesan Santulli, Carlo Department of Mechanical Engineering PTR College of Engineering and Technology Austinpatti Madurai – Tirumangalam Road Tamil Nadu Madurai625008. India Centre for Material Science Department of Mechanical Engineering Karpagam Academy of Higher Education Tamil Nadu Coimbatore641 021 India Department of Mechanical and Aerospace Engineering Carleton University 1125 Colonel By Drive OttawaONK1S 5B6 Canada Department of Mechanical Engineering College of Engineering Imam Mohammad Ibn Saud Islamic University Riyadh Saudi Arabia School of Science and Technology Università di Camerino Camerino Italy

This research explores natural fiber composites (NFCs) as alternatives to traditional materials such as fiberglass. By examining fibers like abaca, bamboo, banana, coir, flax, hemp, jute, kenaf, pineapple leaf (PALF), sisal, and others, we emphasize their lower weight, cost-effectiveness, competitive mechanical properties, commendable specific strength, and potential for biodegradability. NFCs offer practical and eco-friendly substitutes for conventional composite fibers in industries like construction, automotive, and packaging. The article provides a brief overview of NFCs, covering their chemical, physical, and mechanical characteristics, and highlights diverse applications. The comparative analysis underscores the potential of natural fibers as sustainable choices in various industries. © 2024 The Authors

关键词： Hemp

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Study on the Characteristics of Novel Natural Fiber Extracted from Crescentia cujete Plant Fruits—An Alternate Reinforcement for Synthetic materials

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Journal of The Institution of Engineers (India): Series D 2024年 1-9页

作者： Raja, Thandavamoorthy Yuvarajan, Devarajan Material Science Lab Saveetha Dental College and Hospitals SIMATS Saveetha University Tamil Nadu Chennai600077 India Department of Mechanical Engineering Saveetha School of Engineering SIMATS Saveetha University Tamil Nadu Chennai600124 India

This study presents a comprehensive analysis of novel natural fibers extracted from Crescentia cujete plant fruits, exploring their potential as an alternative reinforcement to synthetic materials. Employing a range of characterization techniques, XRD analysis revealed a semi-crystalline structure with a significant crystallinity index of 0.81 and the crystal region of 53.8%, indicating potential for robust applications. FTIR spectroscopy identified key functional groups of the major peak observed at 1020 cm−1 which is related to hemicellulose, C–O–C stretching vibrations in the glycosidic linkages of cellulose, essential for understanding the fibers' chemical composition. Tensile strength tests showed the fibers possess substantial strength of 8.9 MPa and flexibility, making them suitable for reinforcing materials. SEM analysis provided insights into the fibers' surface morphology, crucial for applications requiring strong interfacial bonding. EDX results confirmed the presence of essential elements, highlighting the fibers' natural composition. Furthermore, the antibacterial properties of these fibers were evaluated, showing effectiveness against common bacterial strains, thus broadening their application scope in medical and hygiene products. © The Institution of Engineers (India) 2024.

关键词： Reinforcement

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Influence of Current Density on the Photocatalytic Activity of Nd:TiO_(2) Coatings

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Journal of Wuhan University of Technology(materials science) 2024年第1期39卷 32-38页

作者：施渊吉 ZHANG Zhen DAI Yunzhong LI Jingxiao CHEN Zeyu School of Mechanical Engineering Nanjing Vocational University of Industry TechnologyNanjing 210046China College of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China Key Laboratory of Modern Agricultural Equipment and Technology Jiangsu UniversityZhenjiang 212013China

The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current *** results revealed that the roughness of the coatings increased with the increasing current *** and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile *** the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to *** test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) *** photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement.

关键词： PEO current density AFM XPS Nd:TiO_(2) photocatalytic

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Coercivity mechanism of high-performance anisotropic heterostructure SmCo_(5)magnets

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Journal of Rare Earths 2024年第10期42卷 1882-1888页

作者： Yuan Teng Yuqing Li Weiqiang Liu Xiaochang Xu Zhanjia Wang Jianjun Yang Dongtao Zhang Hongguo Zhang Qingmei Lu Qiong Wu Weixing Xia Ming Yue Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing100124China School of Mechanical and Electrical Engineering Henan Institute of Science and TechnologyXinxiang453000China School of Mechanical Engineering Anyang Institute of TechnologyAnyang455000China Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Material Technology and EngineeringChinese Academy of SciencesNingbo315201China

Due to its large magnetocrystalline anisotropy field and high Curie temperature,SmCo-based magnets are irreplaceable in high-temperature applications,The hot-deformed SmCo-based magnets are especially attractive for their excellent corrosion resistance,making them more suitable for harsh ***,it is still challenging for hot-deformed SmCo-based magnets to obtain high magnetization and high coercivity ***,it is necessary to analyze the relationship between its microstructure and magnetic properties and explore its magnetic hardening mechanism to guide the further improvement of magnetic *** this paper,the anisotropic heterostructure SmCo_(5)magnet was prepared by combining large height-reduction and introducing a nano-grained Smrich *** c-axis texture,(BH)m of 16.1 MGOe,and H_(ci)of 9.6 kOe were obtained via the heterostructure with SmCo_(5)micron-grain and Sm-rich nano-scale *** magnetic domain observation and technical magnetization analysis demonstrate that the coe rcivity mechanism is dominated by *** results also show that the smooth and Sm-rich precipitated grain boundary provides weak pinning *** provides a reference for the development of high-pe rformance nanocrystalline SmCo_(5)magnets.

关键词： Permanent magnet Heterostructure Rare earths Coercivity mechanism Hot-deformed SmCo magnet

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Ni_(3)Fe/Ni_(4)S_(3)/Ni/C Mixed Crystal Composite Nanofibers Prepared by Electrospinning and Heat Treatment Methods for Oxygen Evolution Reaction

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Journal of Wuhan University of Technology(materials science) 2023年第2期38卷 267-273页

作者： LI Tao ZHONG Shujie LOU Qiongyue LING Shuai CHEN Jian MA Guohua YANG Mao WU Xiaoqiang Department of Materials Engineering School of Mechanical EngineeringChengdu UniversityChengdu610106China Material Corrosion and Protection Key Laboratory of Sichuan Province Zigong643000China Analysis and Testing Center Southwest University of Science and TechnologyMianyang621010China

OER catalyst of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C(NiFeSC series)mixed crystal composite nanofibers was prepared by electrospinning and atmospheric heat treatment *** testing results indicate that the diameters of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite nanofibers is about 200 nm,the grains size is about 1-3 nm,and the fiber surface is *** electrochemical test results show that the heterojunction of the prepared Ni_(3)Fe/Ni_(4)S_(3)/Ni/C hybrid crystal composite nanofiber has synergistic effect with sulfide,and exhibits good electrocatalytic activity of water decomposition and OER in alkaline *** OER electrocatalytic performance of Ni_(3)Fe/Ni_(4)S_(3)/Ni/C composite electrode prepared via a heat treatment at 1000℃process was tested in 1 mol/L KOH *** results show that the overpotential is about 298 mV,the Tafel slope is about 74 mV?dec-1,and the surface resistance is about 1.69Ω·cm^(2),at the current density of 10 mA·cm^(-2).

关键词： mixed crystal composite material nanofiber NiFeSC oxygen evolution reaction(OER)

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Advancing optothermal manipulation:decoupling temperature and flow fields in quasi-isothermal microscale streaming

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Light(science & Applications) 2023年第9期12卷 1713-1714页

作者： Youngsun Kim Yuebing Zheng Materials Science and Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX78712USA Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX78712USA

By decoupling temperature and flow fields through symmetry-correlated laser scan sequences,ISO-FLUCS enables quasi-isothermal optofluidic microscale *** technique offers precise control over fluid manipulation while m... 详细信息

关键词： thermal isothermal flow

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Sulfonation of HwBKP by Sulfur Trioxide Pyridine Complex and Preparation of Anionic Cellulose Beads Using the Same

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Palpu Chongi Gisul/Journal of Korea Technical Association of the Pulp and Paper Industry 2023年第2期55卷 10-18页

作者： Kim, Younglae Heo, Dohyeon Cho, Byoung-Uk Department of Paper Science & Engineering College of Forest & Environmental Sciences Kangwon National University Korea Republic of Program of Paper Material Science & Engineering College of Forest & Environmental Sciences Kangwon National University Korea Republic of

To expand the applications of cellulose beads, sulfonated cellulose beads were prepared by chemically modifying HwBKP fibers with sulfur trioxide pyridine complex (STP), dissolving in tetraethylammonium hydroxide (TEAOH)/urea solvent, and dropping into acetic acid solution. The effect of the amount of STP added on the properties of sulfonated cellulose solution and cellulose beads was investigated. It was observed that the sulfonated cellulose beads exhibited anionic surface charge in a fairly wide pH range, and the degree of substitution of sulfonic acid groups and the zeta potential of the cellulose beads could be controlled by adjusting the amount of added STP. In addition, as the amount of STP added increased, the crystallinity of the cellulose decreased, the viscosity and surface tension of the sulfonated cellulose/TEAOH/urea solution decreased, and the size of the cellulose beads increased. © 2023 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.

关键词： Zeta potential

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Polarization pinning at antiphase boundaries in multiferroic YbFeO_(3)

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Chinese Physics B 2024年第11期33卷 39-45页

作者： Guodong Ren Pravan Omprakash Xin Li Yu Yun Arashdeep S.Thind Xiaoshan Xu Rohan Mishra Institute of Materials Science and Engineering Washington University in St.LouisSt.LouisMO 63130USA Department of Physics and Astronomy University of NebraskaLincolnNE 68588USA Department of Mechanical Engineering & Mechanics Drexel UniversityPhiladelphiaPA 19104-2875USA Nebraska Center for Materials and Nanoscience University of NebraskaLincolnNE 68588USA Department of Mechanical Engineering and Material Science Washington University in St.LouisSt.LouisMO 63130USA

The switching characteristics of ferroelectrics and multiferroics are influenced by the interaction of topological defects with domain *** report on the pinning of polarization due to antiphase boundaries in thin films of the multiferroic hexagonal YbFeO_(3).We have directly resolved the atomic structure of a sharp antiphase boundary(APB)in YbFeO_(3) thin films using a combination of aberration-corrected scanning transmission electron microscopy(STEM)and total energy calculations based on density-functional theory(DFT).We find the presence of a layer of FeO_(6) octahedra at the APB that bridges the adjacent *** imaging shows a reversal in the direction of polarization on moving across the APB,which DFT calculations confirm is structural in nature as the polarization reversal reduces the distortion of the FeO_(6) octahedral layer at the *** APBs in hexagonal perovskites are expected to serve as domain-wall pinning sites and hinder ferroelectric switching of the domains.

关键词： hexagonal ferrites ferroelectric multiferroic topological defect STEM

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