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Fabrication of SiC_p/AA5083 composite via friction stir welding

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中国有色金属学会会刊：英文版 2012年第S3期22卷 634-638页

作者： Byung-Wook AHN Don-Hyun CHOI Yong-Hwan KIM seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University

Microstructure and mechanical properties of SiCp /AA5083 composite fabricated by friction stir welding (FSW) were *** influence of the number of FSW passes on the distribution of SiC particles and mechanical properties in the joint was *** one pass,the SiC particles were entangled in the upper side of the stir zone (SZ).However,the particle distribution became more uniform after two passes due to the repeated stirring of the *** the SiC particles facilitate the grain refinement in the SZ by the pinning effect,the particle including region has much smaller grain size than the SZ without SiC *** SiCp /AA5083 composite region exhibits a Vickers hardness of HV90,which is much higher than the value of HV80 in the SZ produced by FSW without SiC particles.

关键词： metal matrix composite SiC particle friction stir welding mechanical property

Microstructure and mechanical property of A356 based composite by friction stir processing

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Transactions of Nonferrous Metals Society of China 2013年第2期23卷 335-340页

作者： Don-Hyun CHOI Yong-Hwan KIM Byung-Wook AHN Yong-Il KIM seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University300 Cheoncheon-dong Jangan-gu Suwon Gyeonggi-do 440-746 Korea MEPL Sungkyunkwan University 300 Cheoncheon-dong Jangan-gu Suwon Gyeonggi-do 440-746 Korea

Friction stir processing （FSP） was used to incorporate SiC particles into the matrix of A356 Al alloy to form composite material. Constant tool rotation speed of 1800 r/min and travel speed of 127 mm/min were used in this study. The base metal （BM） shows the hypoeutectic Al-Si dendrite structure. The microstructure of the stir zone （SZ） is very different from that of the BM. The eutectic Si and SiC particles are dispersed homogeneously in primary Al solid solution. The thermo-mechanically affected zone （TMAZ）, where the original microstructure is greatly deformed, is characterized by dispersed eutectic Si and SiC particles aligned along the rotational direction of the tool. The hardness of the SZ shows higher value than that of the BM because some defects are remarkably reduced and the eutectic Si and SiC particles are dispersed over the SZ.

关键词： friction stir processing A356 alloy SiC powder eutectic Si

Hybrid Friction Stir Welding of High-carbon Steel

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Journal of Materials Science & Technology 2011年第2期27卷 127-130页

作者： Don-Hyun Choi Chang-Yong Lee Byung-Wook Ahn jung-Hyun Choi Yun-Mo Yeon Keun Song seung-Gab Hong Won-Bae Lee Ki-Bong Kang seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University 300 Cheoncheon-dongJangan-guSuwonGyeonggi-do 440-746South Korea Department of Mechanical Engineering Korea Advanced Institute of Science and Technology 335 GwahangnoYuseong-guDaejeon 305-701South Korea Department of Advanced Materials Application Suwon Science College 9-10Botong-liJeongnam-myeonHwasungGyeonggi-do 445-742South Korea Technical Research Lab POSCO Corp.Goedong-dongNam-guPohangGyeongbuk790-785South Korea

A high-carbon steel joint,SK5（0.84 wt% C）,was successfully welded by friction stir welding（FSW）,both without and with a gas torch,in order to control the cooling rate during *** welding,the weld zone comprised gray and black regions,corresponding to microstructural variation：a martensite structure and a duplex structure of ferrite and cementite,*** volume fraction of the martensite structure and the Vickers hardness in the welds were decreased with the using of the gas torch,which was related with the lower cooling rate.

关键词： Friction stir welding High-carbon steel Transformation Martensite

Characterization of flexible copper laminates fabricated by Cu electro-plating process

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中国有色金属学会会刊：英文版 2009年第4期19卷 965-969页

作者： Chang-Min LEE Jun-Hyung LIM Soo-Min HWANG Eui-Cheol PARK Jong-Hyun SHIM Jin-Hyun PARK Jinho JOO seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology,texture,hardness,electrical resistivity and folding behavior was *** achieve Cu layers with similar thicknesses,the current density was varied in the range of 0.2-3 A/dm2 and the plating time was controlled in the range of 0.5-7.5 h to compensate for the variation of the current *** surface morphology,hardness,and folding behavior were characterized by atomic force microscopy,nanoindentation technique and Massachusett Institute of Technology folding endurance test,*** X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases;however,the preferred orientation changed from(220) to(111) as the current density increased over 1 A/*** addition,it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased *** electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000,which were comparable to those of commercial FCCLs.

关键词：电镀工艺层压板铜层制备表征电流密度原子力显微镜纳米压痕技术

Fabrication of two-layer flexible copper clad laminate by electroless-Cu plating on surface modified polyimide

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中国有色金属学会会刊：英文版 2009年第4期19卷 970-974页

作者： Soo-Min HWANG Jun-Hyung LIM Chang-Min LEE Eui-Cheol PARK Jun-Hyuk CHOI Jinho JOO Hoo-Jeong LEE seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University

A flexible copper clad laminate(FCCL) was fabricated using electroless-and electro-Cu plating processes and the effects of pre-treatment time on the adhesion strength of the FCCL were evaluated based on interfacial *** neutralization and catalyst time were varied in the range of 0-20 min and 0.1-10 min,respectively,and the interfacial condition of the FCCL was characterized by atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS).It is observed that the peel strength increases significantly as the neutralization and catalyst time *** strength as high as 7.2-7.3 N/cm is obtained as the neutralization and catalyst time increase up to 20 min and 10 min,respectively,which is comparable to the strength achieved by the conventional laminating and sputtering *** improvements are probably due to an increase in the surface roughness of polyimide(PI),the activated surface condition,and the adsorption of palladium ions/atoms(Pd) on the PI surface which act as nucleation sites for Cu.

关键词：聚酰亚胺表面改性化学制备层压板铜电镀铜箔软性 X射线光电子能谱

Effect of SiC particles on microstructure and mechanical property of friction stir processed AA6061-T4

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中国有色金属学会会刊：英文版 2012年第S3期22卷 614-618页

作者： Don-Hyun CHOI Yong-Il KIM DAE-Up KIM seung-boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University MEPL Sungkyunkwan University KITECH 838-11Palbok-dong 2-gaDeokjin-guJeonju-cityJeollabuk-do 561-844Korea

Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried *** particles were uniformly dispersed into an AA6061-T4 *** SiC particles promoted the grain refinement of the AA6061-T4 matrix by *** mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC *** microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.

关键词： friction stir processing AA6061-T4 SiC particles pinning effect

Adverse effects of early-life stress:focus on the rodent neuroendocrine system

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Neural Regeneration Research 2024年第2期19卷 336-341页

作者： seung Hyun Lee Eui-Man jung Department of Molecular Biology College of Natural SciencesPusan National UniversityBusanRepublic of Korea

Early-life stress is associated with a high prevalence of mental illnesses such as post-traumatic stress disorders,attention-deficit/hyperactivity disorder,schizophrenia,and anxiety or depressive behavior,which constitute major public health *** the early stages of brain development after birth,events such as synaptogenesis,neuron maturation,and glial differentiation occur in a highly orchestrated manner,and external stress can cause adverse long-term effects throughout *** body utilizes multifaceted mechanisms,including neuroendocrine and neurotransmitter signaling pathways,to appropriately process external *** individuals first exposed to early-life stress deploy neurogenesis as a stress-defense mechanism;however,in adulthood,early-life stress induces apoptosis of mature neurons,activation of immune responses,and reduction of neurotrophic factors,leading to anxiety,depression,and cognitive and memory *** process involves the hypothalamus-pituitary-adrenal axis and neurotransmitters secreted by the central nervous system,including norepinephrine,dopamine,and *** rodent early-life stress model is generally used to experimentally assess the effects of stress during *** paper reviews the use of the early-life stress model and stress response mechanisms of the body and discusses the experimental results regarding how early-life stress mediates stress-related pathways at a high vulnerability of psychiatric disorder in adulthood.

关键词： early-life stress hypothalamic-pituitary-adrenergic axis maternal separation mental illness neurodevelopmental disorder neuroendocrine system neurotransmitter

MXene-based hybrid materials for electrochemical and photoelectrochemical H_(2) generation

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Journal of Energy Chemistry 2024年第6期93卷 111-125,I0004页

作者： Jun Young Kim seung Hun Roh Chengkai Xia Uk Sim jung Kyu Kim School of Material Science and Engineering North University of ChinaTaiyuan 030051China School of Chemical Engineering Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea Hydrogen Energy Technology Laboratory Korea Institute of Energy Technology(KENTECH)NajuJeollanamdo 58330Republic of Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University(SKKU)2066Seobu-roJangan-guSuwon 16419Republic of Korea

The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar *** aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse ***(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent *** achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based *** characteristics make them an ideal catalyst material for the ***-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface ***,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water ***,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.

关键词： MXene Hybrid materials EC PEC HER OER Water splitting

Electric-field-controlled highly regioselective thiocyanation of N-containing heterocycles

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Science China Chemistry 2024年第4期67卷 1263-1269页

作者： Ming Gong Qian Wu jung Keun Kim Mengmeng Huang Yabo Li Yangjie Wu Jong seung Kim Henan Key Laboratory of Chemical Biology and Organic Chemistry Key Laboratory of Applied Chemistry of Henan UniversitiesCollege of ChemistryZhengzhou UniversityZhengzhou 450052China Department of Chemistry Korea UniversitySeoul 02841Korea

Achieving highly regioselective synthesis in organic chemistry is challenging due to the uncontrollable orientation between reacting *** electric fields(EEFs)can influence the reactivity and selectivity of the substrate by causing directional ***,scalable and efficient techniques for using EEFs as“smart catalysts”have been lacking,hindering their *** this study,we present a novel method for modifying the regioselectivity of quinoxaline-2(1H)-ones by functionalizing their C7-position using the electric double layer(EDL)*** approach led to moderate to good yields of the corresponding C7-thiocyanation *** calculations and control experiments demonstrated that EEFs could reverse the regioselectivity of quinoxaline-2(1H)-ones,allowing the C7-thiocyanation to proceed via a radical reaction ***,the resulting 7-thiocyano-1-methylquinoxaline-2(1H)-ones exhibited promising AIE *** work showcases a promising strategy for achieving highly regioselective functionalization by aligning the electric field with the desired reaction/bond axis.

关键词： electric fields reaction-axis rule electric double layer C7-thiocyanation C-S bond formation