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Effects of Alloying Elements on the Microstructures and Mechanical Properties of Heavy Section Ductile Cast Iron

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Journal of Materials Science & Technology 2007年第1期23卷 97-101页

作者： G.S.Cho k.H.Choe k.w.lee A.Ikenaga Advanced Material Processing Team Korea Institute of Industrial Technology994-32Dongchun-DongYeonsu-KuIncheon 406-130South Korea Department of Metallurgy and Materials Science Graduate School of EngineeringOsaka Prefecture University1-1Gakuen-ChoSakaiOsaka 599-8531Japan

The effects of alloying elements on the as-cast microstructures and mechanical properties of heavy section ductile cast iron were investigated to develop press die material having high strength and high ductility. Measurements of ultimate tensile strength, 0.2% proof strength, elongation and unnotched Charpy impact energy are presented as a function of alloy amounts within 0.25 to 0.75 wt pct range. Hardness is measured on the broken tensile specimens. The small additions of Mo, Cu, Ni and Cr changed the as-cast mechanical properties owing to the different as-cast matrix microstructures. The ferrite matrix of Mo and Ni alloyed cast iron exhibits low strength and hardness as well as high elongation and impact energy. The increase in Mo and Ni contents developed some fractions of pearlite structures near the austenite eutectic cell boundaries, which caused the elongation and impact energy to drop in a small range. Adding Cu and Cr elements rapidly changed the ferrite matrix into pearlite matrix, so strength and hardness were significantly increased. As more Mo and Cr were added, the size and fraction of primary carbides in the eutectic cell boundaries increased through the segregation of these elements into the intercellular boundaries.

关键词： Heavy section ductile cast iron Alloying elements As-cast microstructures As-cast mechanical properties

Effect of Applied Pressure on the Joining of Combustion Synthesized Ni_3Al Intermetallics with Al Alloy

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Journal of Materials Science & Technology 2008年第1期24卷 123-126页

作者： G.S.Cho J.H.Yang k.H.Choe k.w.lee A.Ikenaga Advanced Material Processing Team Korea Institute of Industrial Technology 7-47 Songdo-Dong Yeonsu-Ku Incheon 406-840 Korea Department of Metallurgy and Materials Science Graduate School of Engineering Osaka Prefecture University 1-1 Gakuen-Cho Sakai Osaka 599-8531 Japan

we focused on the surface reinforcement of ligth weight casting alloys with Ni-AI intermetallic compounds by in-situ combustion reaction to improve the surface properties of non-ferrous casting *** our previous works,green compact of elemental Ni and Al powders were reacted to form Ni-3Al intermetallic compound by SHS （Self-propagating high temperature synthesis） reaction with the heat of molten Al alloy and simultaneously bonded with Al casting *** some defects such as tiny cracks and porosities were remained in the reacted *** we applied pressure to prevent thermal cracks and fill up the pores with liquid Al alloy by squeeze casting *** compressed Al alloy bonded with the Ni-3Al intermetallic compound was sectioned and observed by optical microscopy and scanning electron microscopy （SEM）.The stoichiometric compositions of the intermetallics formed around the bonded interface and in the reacted compact were identified by energy dispersive spectroscopy （EDS） and electron probe micro analysis （EPMA）. Si rich layer was formed on the Al alloy side near the bonded interface by the sequential solidification of Al *** porosities observed in the reacted Ni-3Al compact were filled up with the liquid AI *** Si particles from the molten Al alloy were detected in the pores of reacted Ni-3Al intermetallic *** Al casting alloy and Ni-3Al intermetallic compound were joined very soundly by applying pressure to the liquid Al alloy.

关键词： Joining Combustion synthesis Ni3AI Intermetallic compound Squeeze casting

Elevated brain temperature under severe heat exposure impairs cortical motor activity and executive function

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Journal of Sport and Health Science 2024年第2期13卷 233-244页

作者： Xiang Ren Tan Mary C.Stephenson Sharifah Badriyah Alhadad kelvin w.Z.Loh Tuck wah Soong Jason k.w.lee Ivan C.C.Low Health and Social Sciences Singapore Institute of TechnologySingapore 138683Singapore Human Potential Translational Research Programme Yong Loo Lin School of MedicineNational University of SingaporeSingapore 117597Singapore Centre for Translational Magnetic Resonance Research Yong Loo Lin School of MedicineNational University of SingaporeSingapore 117549Singapore Department of Physiology Yong Loo Lin School of MedicineNational University of SingaporeSingapore 117593Singapore Heat Resilience and Performance Centre Yong Loo Lin School of MedicineNational University of SingaporeSingapore 117510Singapore N.1 Institute for Health National University of SingaporeSingapore 117456Singapore Campus for Research Excellence and Technological Enterprise(CREATE) Singapore 138602Singapore

Background:Excessive heat exposure can lead to hyperthermia in humans,which impairs physical performance and disrupts cognitive *** heat is a known physiological stressor,it is unclear how severe heat stress affects brain physiology and ***:Eleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal temperatures(T_(re))attained 39.5℃,inducing exertional or passive hyperthermia,*** a separate trial,blended ice was ingested before and during exercise as a cooling *** were compared to a control condition with seated rest(normothermic).Brain temperature(T_(br)),cerebral perfusion,and task-based brain activity were assessed using magnetic resonance imaging ***:T_(br)in motor cortex was found to be tightly regulated at rest(37.3℃±0.4℃(mean±SD))despite fluctuations in T_(re).with the development of hyperthermia,T_(br)increases and dovetails with the rising T_(re).Bilateral motor cortical activity was suppressed during high-intensity plantarflexion tasks,implying a reduced central motor drive in hyperthermic participants(T_(re)=38.5℃±0.1℃).Global gray matter perfusion and regional perfusion in sensorimotor cortex were reduced with passive *** function was poorer under a passive hyperthermic state,and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital ***,ingestion of blended ice before and during exercise alleviated the rise in both T_(re)and T_(bc)and mitigated heat-related neural ***:Severe heat exposure elevates T_(br),disrupts motor cortical activity and executive function,and this can lead to impairment of physical and cognitive performance.

关键词： Brain functional activity Cognition Heat stress Hyperthermia Motor function

Study of the Interface between Steel Insert and Aluminum Casting in EPC

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Journal of Materials Science & Technology 2008年第1期24卷 60-64页

作者： k.H.Choe k.S.Park B.H.kang G.S.Cho k.Y.kim k.w.lee M.H.kim A.Ikenaga S.koroyasu Advanced Material Processing Team korea Institute of Industrial Technology IncheonKorea Department of Materials Engineering korea University of Technology and Education ChoongnamKorea Department of Materials Science and Engineering Inha University IncheonKorea Department of Metallurgy and Materials Science Graduate School of Engineering Osaka Prefecture UniversityOsakaJapan Department of Mechanical and Precision Systems Teiko University UtsunomiyaJapan

The effective surface treatment method for steel insert composited with Al base metal by expendable pattern casting （EPC） process and the bonding interface between steel insert and Al base metal were *** was found that Zn plating on steel insert was effective on improving the bonding property between steel insert and Al base metal in EPC *** is thought to promote the formation of diffusion *** almost none content of Zn was observed in the boundary which had been plated on the steel insert.A diffusion layer consisting of Al,Si and Fe was formed at the insert/alloy interface and its hardness was higher than the steel insert as matter of course Al base *** layer turned out to be intermetallic compounds of Al-Si-Fe *** pouring temperature promoted the diffusion of Fe into Al alloy,so Fe content in intermetallic layers increased at higher pouring *** layer nearest to steel disappeared due to applied pressure.

关键词： Expendable pattern casting Insert casting Intermetallic compound Al-Si-Fesystem

钙钛矿La0.8Ca0.2MnO3多晶样品的制备及低温磁学特性

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低温物理学报 2012年第4期34卷 302-305页

作者：姜炳植 S.G.Min S.C.Yu k.w.lee 延边大学理学院物理系 Advanced Materials Research Institute University of New Orleans Department of Physics Chungbuk National University korea Research Institute of Standard and Science

我们利用固相反应法制备了粉末状La0.8Ca0.2MnO3样品,其空间群为pnma,样品中存在超顺磁性粒子,其截止态和超顺磁态的转变温度为185k,从dσ/dT的负峰得到铁磁-顺磁相变居里温度为210k,在顺磁领域线性拟合而得到顺磁居里温度为216.4k,分... 详细信息

我们利用固相反应法制备了粉末状La0.8Ca0.2MnO3样品,其空间群为pnma,样品中存在超顺磁性粒子,其截止态和超顺磁态的转变温度为185k,从dσ/dT的负峰得到铁磁-顺磁相变居里温度为210k,在顺磁领域线性拟合而得到顺磁居里温度为216.4k,分子式有效磁矩为6.25μB,低温领域磁化曲线服从布洛赫T32定律,其自旋波劲度系数为49.2meV2.

关键词：钙钛矿锰氧化物居里温度自旋波劲度系数

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超声波对分散染料粒度的影响

国外纺织技术（纺织针织服装化纤染整） 2002年第2期 30-32页

作者： k.w.lee 郑敏

分散染料的粒度多种多样,在染浴中通常以晶体形式存在,粒度的分布随染料整理方式的不同而不同,为了获得所需要的粒度和粒度分布,分散染料通常要在分散剂存在下加以碾磨.

关键词：织物染色超声波分散染料粒度上染率

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聚对苯二甲酸乙二(醇)酯超声波染色的特点

国外纺织技术（纺织针织服装化纤染整） 2004年第6期 28-30,40页

作者： k.w.lee 赵晓兰

近来,人类对于如何解决纺织品染色和整理工序所带来的环境问题进行了大量的研究.人们引进了各种新的工艺,甚至把超声波作为解决环境问题的方法进行了研究.

关键词：纺织品整理聚对苯二甲酸乙二(醇)酯超声波染色环境问题

结肠癌病人胸部CT分期的阳性诊断率及假转诊率

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国际医学放射学杂志 2019年第1期 108-109页

作者： k.H.lee J.H.Park Y.H.kim k.w.lee J.w.kim H.k.Oh 张惠敏 Department of Radiology Seoul National University Bundang HospitalSeoul National University College of Medicine

摘要目的基于结肠癌病人腹部增强CT的临床分期,测定胸部增强CT分期的阳性诊断率及假转诊率。材料与方法本回顾性研究纳入1 743例被诊断为结肠癌的病人(年

关键词：结肠癌 CT

心脏CT检查发现肺癌:流行病学、临床放射学特征及全视野图像观察的重要性

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国际医学放射学杂志 2010年第4期 369-370页

作者： T.J.kim k.w.lee 李宁 Department of Radiology Seoul National University Bundang Hospital300 Gumi-dongBundang-guSeongnam-siGyeonggi-do 463-707Korea

目的回顾性评价心脏CT检查发现肺癌的流行病学及临床放射学特征,并比较不同视野设置的检出率。材料与方法该回顾性研究获伦理委员会批准,无需病人知情同意书。回顾性研究2

关键词：肺癌肺肿瘤心脏视野 CT 流行病学放射学