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Fluoride evaporation and crystallization behavior of CaF_2–CaO–Al_2O_3–(TiO_2) slag for electroslag remelting of Ti-containing steels

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International Journal of Minerals,Metallurgy and Materials 2016年第6期23卷 627-636页

作者： Cheng-bin Shi jung-wook cho Ding-li Zheng Jing Li State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Graduate Institute of Ferrous Technology Pohang University of Science and Technology

To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2–CaO–Al2O3–（TiO2） slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite（CaTiO3） crystals instead of CaO crystals in the slag. The crystallization of perovskite（CaTiO3） occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

关键词： electroslag remelting slag crystallization crystallization kinetics fluorides evaporation

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Effect of SiO2 substitution with Al2O3 during high-Al TRIP steel casting on crystallization and structure of low-basicity CaO–SiO2-based mold flux

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Journal of Iron and Steel Research International 2020年第1期27卷 33-41页

作者： Ding-li Zheng Cheng-bin Shi Zhi-jun Li Jing Li jung-wook cho State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Division of Steelmaking Shougang Qian’an Iron and Steel Co.Ltd.Qian’an 064404HebeiChina Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 790-784Republic of Korea

The crystallization and structure of non-conventional lime-silica-based mold fluxes after undergoing slag-steel interaction in casting high-AI transformation induced plasticity(TRIP)steel were *** results showed that the crystallization temperatures of the mold fluxes decreased with decreasing the SiO2/Al2O3 ratio,and CaO/MnO2 ratio had an opposite effect on the crystallization *** crystalline phases precipitated in the mold flux were Ca4Si2O7F2 and *** SiO2/Al2O3 ratio and increasing CaO/MnO2 ratio in the mold fluxes have no influence on the types of crystalline *** dominant crystalline phase precipitated in each mold flux was Ca4Si2O7F2 with dendritic morphology,except for part of that with globular morphology in the mold flux without MnO2 ***4 crystals are distributed in the space among Ca4Si2O7F2 *** size of Ca4Si2O7F2 crystals in the slag with higher S1O2/AI2O3 ratio is smaller,which is attributed to the polymerization degree of the mold flux with increasing SiO2/Al2O3 ratio.[SiO4]-tetrahedral,[AlO4]-tetrahedral and T-O-T bending(T denotes Si or Al)depolymerized gradually with decreasing SiO2/Al2O3 ratio,and an opposite trend was observed for the case with increasing CaO/MnO2 *** polymerization degree of the mold fluxes decreased,which would result in the decrease in the viscosity of the mold fluxes.

关键词： Mold flux Crystallization Structure Continuous casting High-AI steel

Effect of TiO_2 on the viscosity and structure of low-fluoride slag used for electroslag remelting of Ti-containing steels

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International Journal of Minerals,Metallurgy and Materials 2017年第1期24卷 18-24页

作者： Cheng-bin Shi Ding-li Zheng Seung-ho Shin Jing Li jung-wook cho State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Graduate Institute of Ferrous Technology Pohang University of Science and Technology

The viscosity of CaF_2-CaO-Al_2O_3-MgO-（TiO_2） slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of the slag was found to decrease with increasing TiO_2 content in the slag from 0 to 9.73wt%. The activation energy decreased from 95.16 kJ /mol to 79.40 kJ /mol with increasing TiO_2 content in the slag. The introduction of TiO_2 into the slag played a destructive role in Al-O-Al structural units and Q^4 units by forming simpler structural units of Q^2 and Ti_2O_6^（4-） chain. The amount of Al-O-Al significantly decreased with increasing TiO_2 content. The relative fraction of Q^4 units in the [AlO_4]^（5-）-tetrahedral units shows a decreasing trend, whereas the relative fraction of Q^2 units and Ti_2O_6^（4-） chain increases with increasing TiO_2 content accordingly. Consequently, the polymerization degree of the slag decreases with increasing TiO_2 content. The variation in slag structure is consistent with the change in measured viscosity.

关键词： electroslag remelting slag titanium dioxide viscosity structure

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Switchable p-n-p conduction and thermoelectric properties of selenium-doped tellurium crystal

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Rare Metals 2024年第11期 5975-5984页

作者： Stanley Abbey Hanhwi Jang Brakowaa Frimpong Van Quang Nguyen Sunglae cho Yeon Sik jung Min-wook Oh Department of Materials Science and Engineering Hanbat National University Department of Materials Science and Engineering Korea Advance Institute of Science and Technology Department of Phy sics and Energy Harvest-Storage Research Center University of Ulsan

Switchable conductivity in elementary semiconducting materials has a high potential for the design of diodes,transistors and energy conversion ***,the ability to utilize their physical properties is dependent on doping within the carrier density transition ***-crystal tellurium has a high Seebeck coefficient and intrinsic p-n-p conduction at room temperature and therefore,is not suitable for thermoelectric *** demonstrate that the addition of iso valent Se lowers the Fermi level to achieve a stable p-type conductivity with a high band degeneracy near the valence *** observed shifts in the n-p transition temperature below the intrinsic conductivity at 470 K based on changes in stoichiometry and carrier concentration above *** addition,the high thermal conductivity is significantly reduced with the increase in Se alloying due to the mass and strain *** results in a moderately high zT of 0.4 at 673 K.

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Intracellular zinc signaling via Kruppel-like transcription factor 6 promotes HuD expression in pancreatic β cell

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Genes & Diseases 2024年第4期11卷 24-27页

作者： Seongho Cha chongtae Kim Myeongwoo jung Seungyeon Ryu Sukyoung Han wook Kim Eun Kyung Lee Department of Biochemistry Department of Biomedicine&Health SciencesCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea Catholic Institute for Visual Science College of MedicineThe Catholic University of KoreaSeoul 06591South Korea Department of Molecular Science&Technology Ajou UniversitySuwon 16499South Korea

Dysfunction of pancreaticβcells caused by zinc deficiency is related to the pathogenesis of diabetes.1 Impaired zinc homeostasis in diabetes is associated with reduced zinc transporters.2 Down-regulation of HuD,an es... 详细信息

关键词： βcell homeostasis zinc

Realizing High Thermoelectric Performance in n-Type Se-Free Bi2Te3 Materials by Spontaneous Incorporation of FeTe2 Nanoinclusions

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Energy & Environmental Materials 2024年第4期7卷 344-354页

作者： Jamil Ur Rahman Woo Hyun Nam Yong-Jae jung Jong Ho Won Jong-Min Oh Nguyen Van Du Gul Rahman Víctor M.García-Suárez Ran He Kornelius Nielsch jung Young cho Won-Seon Seo Jong wook Roh Sang-il Kim Soonil Lee Kyu Hyoung Lee Hyun Sik Kim Weon Ho Shin Leibniz Institute for Solid State and Materials Research Advanced Materials Convergence R&D Division Korea Institute of Ceramic Engineering & Technology Department of Electronic Materials Engineering Kwangwoon University Department of Energy Engineering Dankook University Faculty of Fundamental Science Phenikaa University Department of Physics Quaid-i-Azam University Departamento de Física Universidad de Oviedo Nanomaterials and Nanotechnology Research Center-CINN Department of Materials Science and Engineering Yonsei University School of Nano & Materials Science and Engineering Kyungpook National University Department of Materials Science and Engineering University of Seoul School of Materials Science and Engineering Changwon National University

Bi2Te3-based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room ***,the stability of existing n-type Bi2（Te,Se）3materials is still low due to the evaporation energy of Se (37.70 kJ mol-1) being much lower than that of Te (52.55 kJ mol-1).The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency.

关键词： Bi2Te3 energy harvesting FeTe2 nanoinclusion n-type materials thermoelectric

熔融结晶器保护渣喂入技术对TWIP钢连铸坯可浇性能及其表面质量的改进

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钢铁译文集 2018年第1期 47-56页

作者： jung-wook cho 韦菁(译) 郭俊波(校对) 韩国浦项工科大学不详

为了提高连铸生产效率，改善铸坯的表面质量，韩国浦项钢铁公司基于熔融保护渣的喂入技术，开发了一种全新的连铸工艺-PCAST工艺，熔融结晶器保护渣该工艺中，熔融结晶器保护渣用喂线的方式喂入结晶器中，从而提高了弯月面的保温性，由... 详细信息

为了提高连铸生产效率，改善铸坯的表面质量，韩国浦项钢铁公司基于熔融保护渣的喂入技术，开发了一种全新的连铸工艺-PCAST工艺，熔融结晶器保护渣该工艺中，熔融结晶器保护渣用喂线的方式喂入结晶器中，从而提高了弯月面的保温性，由此改善了凝固坯壳与铜结晶器之间的润滑性。先进高Al高强度钢（AHSS）板坯的可浇性与表面质量同时提高是该工艺应用于工业化连铸工艺后的最重要优点之一。在10t试验连铸机和100t、250t工业连铸机上进行TWIP钢的试生产试验。新工艺中的熔融保护渣消耗量超过了0．2kg／m2，远远高于传统工艺的消耗量。在试验连铸机与工厂连铸机的TWIP试浇铸中，结晶器性能（如结晶器传热）均很稳定。另外，连铸板坯显现出周期性／完整的振痕，但几乎没有缺陷。TWIP钢的成功浇铸得益于POCAST的以下特性：熔渣池深度的增加稀释了反应物；渣圈的去除扩大了弯月面处的渣膜的渗透渣道；提高保护渣的温度降低了弯月面处结晶器渣的黏度。

关键词：韩国浦项钢铁公司结晶器保护渣表面质量连铸坯熔融喂入性能技术

Oxygen vacancy engineering for tuning the catalytic activity of LaCoO_(3) perovskite

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Journal of Rare Earths 2024年第3期42卷 506-514,I0003页

作者： Jeong Hyun cho Minjae Kim Inchan Yang Kyung Tae Park Chang Houn Rhee Hai Woong Park Ji Chul jung Department of Chemical Engineering Myongji UniversityYongin 17058Republic of Korea Institute of Advanced Composite Materials Korea Institute of Science and TechnologyWanju-gunJeollabuk-do 55324Republic of Korea Iron&Steel Process Engineering Research Group POSCOPohang 37859Republic of Korea Hydrogen Research Center Research Institute of Industrial Science&Technology(RIST)Pohang 37673Republic of Korea

Herein, we attempted to engineer oxygen vacancies on the surface of LaCoO_(3) perovskite through simple post-treatments(acid or reductive thermal treatments). Acid treatment induces oxygen vacancies through the selective etching of the La cations, whereas thermal treatment in a reducing atmosphere generates oxygen vacancies by directly removing lattice oxygen. The characterization results confirm that the number of surface oxygen vacancies, which are crucial in various catalytic oxidation reactions,considerably increases in the LaCoO_(3) catalysts treated with acid or reducing gas. Acid treatment enriches the oxygen vacancies while maintaining the structure of the LaCoO_(3) catalysts, which can not be achieved through reductive thermal treatment. Therefore, the acid treatment is considered a promising technique for oxygen vacancy engineering of perovskite catalysts for tuning their catalytic activities. Furthermore,the catalytic activities of the posttreated LaCoO_(3) catalysts for CO oxidation were evaluated and are noted to be considerably better than those of the pristine LaCoO_(3) catalyst due to their abundant oxygen vacancies. Consequently, we conclude that the oxygen vacancies of perovskite catalysts can be effectively engineered via two simple methods and play a significant role in CO oxidation.

关键词： LaCoO_(3)perovskite Acid treatment Reductive thermal treatment Oxygen vacancy CO oxidation Rare earths

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Long cycle-life aqueous Zn battery enabled by facile carbon nanotube coating on Cu current collector

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Carbon Energy 2024年第6期6卷 151-164页

作者： Beom-Keun cho Sung-Ho Huh So Hee Kim Seungho Yu Jong-Seong Bae jung-Keun Yoo Seung-Ho Yu Department of Chemical and Biological Engineering Korea UniversitySeoulRepublic of Korea Advanced Analysis Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea Energy Storage Research Center Korea Institute of Science and Technology(KIST)SeoulRepublic of Korea KIST School Division of Energy and Environment TechnologyKorea University of Science and TechnologySeoulRepublic of Korea Busan Center Korea Basic Science Institute(KBSI)BusanRepublic of Korea Carbon Composites Department Composites Research DivisionKorea Institute of Materials Science(KIMS)ChangwonRepublic of Korea

As an alternative to Li-ion batteries,aqueous Zn batteries have gained attention due to the abundance of Zn metal,low reduction potential(-0.76 V *** hydrogen electrode),and high theoretical capacity(820 mAh g^(-1))of multivalent Zn2+***,the growth of Zn dendrites and the formation of irreversible surface reaction byproducts pose challenges for ensuring a long battery lifespan and ***,the Cu foil coated with a single-walled carbon nanotube(SWCNT)layer using a facile doctor blade casting method is *** SWCNT-coated Cu foil demonstrates a significantly longer battery lifespan compared to the bare Cu in the half-cell *** operando optical microscopy imaging,we are able to provide intuitive evidence that Zn deposition occurs between the carbon nanotube(CNT)coating and Cu substrate,in agreement with the computational ***,with various imaging techniques,the flat morphology and homogeneous distribution of Zn beneath the SWCNT layer are *** addition,the full-cell using CNT-coated Cu exhibits a long cycle life compared to the control group,thereby demonstrating improved electrochemical performance with limited Zn for the cycling process.

关键词： aqueous Zn battery carbon nanotube operando imaging surface coating