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Importance of surface oxide for the tribology of a Zr-based metallic glass

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Friction 2017年第1期5卷 115-122页

作者： S.J.KANG K.T.RITTGEN S.G.KwAN h.w.park R.BENNEwITZ A.CARON Department of Materials Sciences and Engineering Zhejiang University Hangzhou 310058 China NM-Leibniz Institute for New Materials Campus D2.2 Saarbrücken 66123 GermanyDepartment of Physics Saarland University Saarbrücken 66123 Germany KoreaTech Korea University of Technology and Education Chungnam Province 330-708 Republic of Korea NM-Leibniz Institute for New Materials Campus D2.2 Saarbrücken 66123 GermanyKoreaTech Korea University of Technology and Education Chungnam Province 330-708 Republic of Korea

Thermally grown surface oxide layers dominate the single-asperity tribological behavior of a Zr60Cu30Al10 *** in oxidation time leads to an increased contribution of shearing and a corresponding decreased contribution of ploughing to *** change in the dominating friction and wear mechanism results in an overall minor decrease of the friction coefficient of oxidized surfaces compared to the metallic glass sample with native surface *** results demonstrate the importance of creating a stable oxide layer for practical applications of metallic glasses in micro-devices involving sliding contact.

关键词： metallic glasses surface oxide friction wear nanotribology atomic force microscopy

Flow Injection Chemiluminescence Determination of L-dopa Using Potassium Permanganate-Sodium Sulfite System

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Flow Injection Chemiluminescence Determination of L-dopa Usi...

Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

第三十五届国际光谱会议

作者： S.M.Alam h.Y.Chung h.w.park S.M wabaidur C.w.Jeon S.h.Lee Department of Chemistry Kyungpook National University Daegu 702-701Korea Department of Chemistry Kyungpook National University Daegu 702-701Korea Department of Chemistry Kyungpook National University Daegu 702-701Korea Department of Chemistry Kyungpook National University Daegu 702-701Korea Korea Institute of Geoscience ＆ Mineral Resources Daejon-305-350 Korea Department of Chemistry Kyungpook National University Daegu 702-701Korea

＜正＞A simple,rapid and precise flow injection chemiluminescence （FI-CL） method is proposed for the determination of L-dopa by combining the flow injection technique and its sensitizing effect on the weak chemiluminescence reaction between sulfite and acidic *** graph showed a linear response for L-dopa concentration in

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Journal of Energy Chemistry 2025年第1期100卷 245-258页

作者： Gaeun Lee Yong Nam Ahn Seongjoon So Chanwoo park Jong-Seong Bae Taehyun park Il Tae Kim Jaehyun hur School of Chemical Biological and Battery Engineering Gachon University Seongnam Busan Center Korea Basic Science Institute

Aqueous Zn-ion batteries （AZIBs） have received considerable attention owing to their various advantages such as safety,low cost,simple battery assembly conditions,and high ionic ***,they still suffer from serious problems,including uncontrollable dendrite growth,corrosion,hydrogen evolution reaction （hER） from water decomposition,electrode passivation,and unexpected *** creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these ***,we propose the use of a perovskite CaTiO3（CTO） protective layer on Zn（CTO@Zn） as a promising approach for improving the performance of *** CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant （εr=180） and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ions in the CTO *** avoiding the direct contact of the Zn anode with the electrolyte solution,the uneven dendrite growth,corrosion,parasitic side reactions,and hER are mitigated,while CTO retains its mechanical and chemical robustness during ***,CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare ***@Zn shows steady overpotential （～68 m V） for 1500 h at 1 mA cm-2/0.5 mA h cm-2,excelling bare ***,when paired with the V2O5-C cathode,the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g-1（based on the mass of the cathode） after 300 *** study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

关键词： Artificial layer Dielectric constant Zn metal anode Zinc aqueous battery

Scalable Ir-Doped NiFe₂O₄/TiO₂ heterojunction Anode for Decentralized Saline wastewater Treatment and h₂ Production

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NANO-MICRO LETTERS 2025年第1期17卷 1-18页

作者： hong, Sukhwa Kim, Jiseon park, Jaebeom Im, Sunmi hoffmann, Michael R. Cho, Kangwoo Pohang Univ Sci & Technol POSTECh Div Environm Sci & Engn Pohang 790784 South Korea CALTECh Linde Labs Pasadena CA 91125 USA Yonsei Univ Int Campus Inst Convergence Res & Educ Adv Technol I CREATE Incheon 21983 South Korea

wastewater electrolysis cells (wECs) for decentralized wastewater treatment/reuse coupled with h-2 production can reduce the carbon footprint associated with transportation of water, waste, and energy carrier. This study reports Ir-doped NiFe2O4 (NFI, similar to 5 at% Ir) spinel layer with TiO2 overlayer (NFI/TiO2), as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral ph in a single-compartment cell. In dilute (0.1 M) NaCl solutions, the NFI/TiO2 marks superior activity and selectivity for chlorine evolution reaction, outperforming the benchmark IrO2. Robust operation in near-neutral ph was confirmed. Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO2 which serves both as the primary site for Cl- chemisorption and a protective layer for NFI as an ohmic contact. Galvanostatic electrolysis of Nh4+-laden synthetic wastewater demonstrated that NFI/TiO2 not only achieves quasi-stoichiometric Nh4+-to-N-2 conversion, but also enhances h-2 generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine. The scaled-up wEC with NFI/TiO2 was demonstrated for electrolysis of toilet wastewater.

关键词： wastewater electrolysis cell Ir-doped NiFe2O4 Reactive chlorine species Decentralized h-2 production On-site wastewater treatment

Liquid-liquid extraction and separation of total rare earth(RE) metals from polymetallic manganese nodule leaching solution

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Journal of Rare Earths 2015年第2期33卷 207-213页

作者： P.K.Parhi K.h.park C.w.Nam J.T.park Mineral Resources Research Division Korea Institute of Geoscience & Mineral Resources (KIGAM)Daejeon 305-350 Republic of Korea School of Applied Science and Center of Industrial Technology KIIT UniversityBhubaneswar 751024 Odisha India

The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca（Oh）2 at ph 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents（D2EhPA, PC88 A, Cyanex 272） were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. ph effect, the performances of above three extractants followed the order as： D2EhPA〉PC88A〉Cyanex 272. To ensure the absence of extraction of base metals（Cu, Co, Ni）, the eq. ph of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. ph with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EhPA. Extraction isotherm plot was constructed at A：O=12：1, 3-stages and phe=2.21, using 0.8 mol/L D2 EhPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current Simulation（CCS） study. The stripping of total rare earth from loaded organic phase（LO） was conducted using hCl solution. Mc-Cabe Thiele diagram study carried out at A：O=1：5 using 4 mol/L hCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction（SX） process.

关键词： total rare earth (RE) metals SX D2EhPA hCl deep sea nodule

Microstructure and creep properties of Mg-4Al-2Sn-1(Ca,Sr) alloys

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1184-1191页

作者： B.h.KIM K.C.park Y.h.park I.M.park Department of Material Science and Engineering Pusan National UniversitySan 30 Jangjeon-dongGeumjeong-guBusan 609-735Korea

The effects of Ca and Sr addition on the microstructure and creep properties of Mg-4Al-2Sn alloys were examined. Tensile tests at 25 ℃ and 200 ℃ and creep tests at 150 ℃ and 200 ℃ were carried out to estimate the room temperature and high temperature mechanical properties of these alloys. The microstrueture of the Mg-4Al-2Sn alloy showed dendritic a-Mg, Mg17Al12 and Mg2Sn phases. The latter two phases precipitated along the grain boundaries. The addition of Ca and Sr resulted in the formation of ternary CaMgSn and SrMgSn phases within the grain. The grain size was reduced slightly with the addition of Sr and Ca. The tensile strength was decreased by the addition of Ca and Sr at room temperature. however, the high temperature tensile strength was increased. The creep strength was improved by the addition of Ca and Sr.

关键词： magnesium alloys Ca Sr void initiation mechanical properties creep mechanism

Evaluation of microstructure and mechanical properties of Mg-xCe-0.5Zn alloys by nano-indentation

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1240-1243页

作者： K.C.park B.h.KIM Y.h.park I.M.park Department of Material Science and Engineering Pusan National UniversitySan 30 Jangjeon-dongGeumjeong-guBusan 609-735Korea

The microstructure and mechanical properties of Mg-xCe-0.5Zn （x=0.5, 1.5, 2.5, molar fraction, %） alloys were examined using a nano-indentation technique. The alloys were fabricated using a vacuum induction melting method under an argon atmosphere The microstruetures of Mg-xCe-0.5Zn alloys mainly consist ofa-Mg and eutectic Mg12Ce phase. The volume fraction and size of the eutectic Mgl2Ce phase increase with increasing Ce contents. Nano-indentation test results show that the indentation hardness and elastic modulus of the eutectic Mg12Ce phase are higher than those of the a-Mg matrix. In addition, the mean indentation hardness and elastic modulus of the Mg-xCe-0.5Zn alloys increase with the Ce addition amount increasing.

关键词： Mg alloys Mg-Ce-Zn rare earth microstructure mechanical properties nano-indentation

Adaptive Functional Projective Lag Synchronization of a hyperchaotic Rossler System

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Chinese Physics Letters 2009年第9期26卷 69-72页

作者： Tae h. Lee Ju h. park Nonlinear Dynamics Group Department of Electrical Engineering Yeungnam University 214-1 Dae-Dong Kyongsan 712-749 Republic of Korea

we explain the functional projective lag synchronization of a hyperchaotic Rossler system with four unknown parameters, where the output of the master system lags behind the output of the slave system proportionally. Based on Lyapunov stability theory, an active control method and adaptive control law are employed to make the states of two hyperchaotic Rossler systems asymptotically synchronized. Finally, some numerical examples are provided to show the effectiveness of our results.

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Influence of alloying elements on microstructure and microhardness of Mg-Sn-Zn-based alloys

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Transactions of Nonferrous Metals Society of China 2010年第12期20卷 2246-2252页

作者： w. L. ChENG S. park w. N. TANG B. S. YOU B. h. KOO School of Nano ＆ Advanced Materials Engineering Changwon National University Changwon 641-773 South Korea Light Metals Research Group Korea Institute of Materials Science （KIMS） Changwon 641-831 South Korea

The phase evolution in （88%-91%）Mg-8%Sn-l%Zn-X （X=A1, Mn and/or Ce） system was analyzed via CALPhAD method and simulations were used in precise selection of the chemical composition. The influence of the addition of different alloying elements such as A1, Mn and Ce on the microstructure and microhardness of Mg-8%Sn-l%Zn-based alloys was investigated. Combined addition of A1 and Mn shows features distinct from separate addition of A1 or Mn. Additions of l%AI and l%Mn to base alloy result in the formation of massive A1-Mn phase in a-Mg matrix grains. Addition of Ce element can refme the second eutectic precipitates and form intermetallic compounds with Sn. Fine rod-like Sn-Ce phase presents mainly on the grain boundaries and plays a role in inhibiting grain growth. The effects of alloying elements on Vickers microhardness and indentation size effect of base alloy were examined.

关键词： magnesium alloys alloying elements CALPhAD method hardness indentation size effect