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Electrodeposited Ni-W-TiC Composite Coatings:Effect of TiC Reinforcement on Microstructural and Tribological Properties

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Acta Metallurgica Sinica(English Letters) 2020年第4期33卷 573-582页

作者： jin hyuk choi Gobinda Gyawali Dhani Ram Dhakal Bhupendra Joshi Soo Wohn Lee Department of Materials Metal Engineering Sun Moon University31460 AsanSouth Korea Department of Fusion Science and Technology Sun Moon UniversityTangjeong Myeon31460 AsanChungnamSouth Korea Department of Environmental and Bio-Chemical Engineering Sun Moon University31460 AsanSouth Korea

Ni-W-TiC composite coatings were prepared via electrodeposition technique by dispersing the different amount of TiC particles into the plating *** Ni-W and Ni-W-TiC composite coatings containing different concentrations of TiC particles were characterized by using the scanning electron microscope,X-ray diffraction technique,Vickers microhardness test,surface roughness test,and tribology *** results show that the Ni-W coatings containing reinforced TiC particles have shown a typical FCC Ni-W crystal structure with significantly higher Vickers *** amount of dispersed TiC particles into the plating bath considerably affected codeposition weight percent of TiC into the Ni-W matrix,as revealed by the EDS ***-W-TiC samples demonstrated the decreased abrasive wear as compared to Ni-W coating and no characteristic features observed for the adhesive ***,an improvement in coefficient of friction was observed in Ni-W-TiC composite coating as compared to Ni-W coating.

关键词： Ni-W alloy Composite coating Microhardness Wear Coefficient of friction

Effect of Pulse and Direct Current Electrodeposition on Microstructure,Surface,and Scratch Resistance Properties of Ni-W Alloy and Ni-W-SiC Composite Coatings

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Acta Metallurgica Sinica(English Letters) 2020年第10期33卷 1321-1330页

作者： Sami Bin Humam Gobinda Gyawali Dhani Ram Dhakal jin-hyuk choi Soo Wohn Lee Department of Environmental and Bio-Chemical Engineering Sun Moon UniversityAsan 31460Korea Department of Fusion Science and Technology Sun Moon UniversityAsan 31460Korea

The present work aims to study the influence of direct current and pulse current techniques as well as embedded SiC nanoparticles on the mechanical properties of the electrodeposited Ni-W *** electrodeposited coatings were studied for morphological,microstructural,mechanical,and scratch resistance properties using the surface roughness tester,scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction,Vickers microhardness,and scratch *** of pulse current exhibited relatively homogeneous and smooth surface of the coatings.A remarkable increment of microhardness was observed in both Ni-W and Ni-W-SiC coatings prepared under pulse current as compared to the direct current ***,the scratch test revealed a considerable improvement in the scratch resistance behavior of the Ni-W alloy and the composite coatings from the pulsed current ***,the application of pulse current not only improved the surface-and microstructure-related properties but also enhanced the Vickers microhardness and scratch resistance properties of the *** addition,the reduction in micro-cracks revealed the improvement in scratch resistance properties of the coatings due to the incorporated SiC nanoparticles into the Ni-W alloy matrix.

关键词： Ni-W-SiC composite Surface Microstructure Microhardness Scratch resistance

Role of surfactants on particle deposition, wear, and corrosion behavior of TaC particle incorporated electroless nickel-phosphorus coating

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Progress in Natural Science:Materials International 2022年第5期32卷 655-663页

作者： jin-hyuk choi Dhani Ram Dhakal Yuwaraj K.Kshetri Bina Chaudhary Bhupendra Joshi Soo Wohn Lee Tae-Ho Kim Research Center for Advance Green Materials Sun Moon University Department of Fusion Science and Technology Sun Moon University

The coatings prepared by incorporating submicron-sized TaC particles while depositing Ni and P atoms on the steel substrate via electroless method showed mixed results of surface finishing, microstructural properties,mechanical, tribological, and corrosion behavior with the addition of various surfactants during the coating process. The surfactant sodium dodecyl sulfate(SDS) enhanced the microhardness when added during the coating process of Ni–P–TaC composite, whereas the cetyltrimethyl ammonium bromide(CTAB) lowered the microhardness as compared to the surfactant-free coating. Moreover, the TaC particle incorporation was hindered by the surfactants CTAB and Triton X-100. An excellent wear resistance behavior has been observed in the surfactantfree Ni–P–TaC coating in comparison to particle-free Ni–P coating. The Ni–P–TaC coatings showed the dependency of wear behavior on the material properties of the counter sliding surface although this dependency has not been observed in Ni–P coatings. The wear damage in Ni–P coating is immense irrespective of the properties of counter-sliding materials. Various surfactant-used Ni–P–TaC coating surfaces deteriorated much more due to corrosion than surfactant-free Ni–P–TaC coating. Among the various surfactants, the CTAB used Ni–P–TaC coating showed weak corrosion resistance.

关键词： Electroless coating NiP-based coating Tantalum carbide Wear Corrosion

High-Throughput Pb Recycling for Perovskite Solar Cells Using Biomimetic Whitlockite

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Energy & Environmental Materials 2023年第3期6卷 170-176页

作者： Jung Sug Hong Hee Jung Kim Chang Hwun Sohn Oh Yeong Gong jin hyuk choi Kang Hee Cho Gill Sang Han Ki Tae Nam Hyun Suk Jung Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Korea

Pb contamination in aquatic environments causes severe pollution;therefore,harmless absorbents are *** this study,we report a novel synthesis of whitlockite(WH,Ca_(18)Mg_(2)(HPO_(4))_(2)(PO_(4))_(12)),which is the second most abundant biomineral in human bone,and its application as a high-performing Pb^(2+)***(HAP)and WH are prepared via a simple precipitation *** Pb2+absorption performance and mechanism of the synthesized biominerals are investigated in aqueous solutions at neutral *** results demonstrate that WH exhibits an excellent Pb2+absorption capacity of 2339 mg g^(−1),which is 1.68 times higher than the recorded value for ***,the absorbed Pb^(2+) ions are recycled into high-purity PbI_(2).This is employed as a precursor for the fabrication of perovskite solar cells(PSCs),resulting in a conversion efficiency of 19.00%comparable to that of commercial PbI2 powder(99.99%purity).Our approach provides an efficient way to remove Pb^(2+)ions from water and reuse them in the recycling of PSCs.

关键词： Pb absorption Pb recycling perovskite solar cells water purification whitlockite

Omnidirectional color wavelength tuning of stretchable chiral liquid crystal elastomers

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Light(Science & Applications) 2024年第6期13卷 1062-1074页

作者： Seungmin Nam Wontae Jung Jun hyuk Shin Su Seok choi Department of Electrical Engineering Pohang University of Science and Technology(POSTECH)PohangKorea

Wavelength-tunable structural colors using stimuli-responsive materials,such as chiral liquid crystals(CLCs),have attracted increasing attention owing to their high functionality in various tunable photonic ***,on-demand omnidirectional wavelength control is highly desirable from the perspective of wavelength-tuning ***,despite numerous previous research efforts on tunable CLC structural colors,only mono-directional wavelength tuning toward shorter wavelengths has been employed in most studies to *** this study,we report the ideally desired omnidirectional wavelength control toward longer and shorter wavelengths with significantly improved tunability over a broadband wavelength *** using areal expanding and contractive strain control of dielectric elastomer actuators(DEAs)with chiral liquid crystal elastomers(CLCEs),simultaneous and omnidirectional structural color-tuning control was *** breakthrough in omnidirectional wavelength control enhances the achievable tuning freedom and versatility,making it applicable to a broad range of high-functional photonic applications.

关键词： tuning tunable directional

Unraveling the Harmonious Coexistence of Ruthenium States on a Self-Standing Electrode for Enhanced Hydrogen Evolution Reaction

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Energy & Environmental Materials 2024年第6期7卷 303-311页

作者： Joonhee Ma jin hyuk Cho Chaehyeon Lee Moon Sung Kang Sungkyun choi Ho Won Jang Sang Hyun Ahn Seoin Back Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoul 02841Korea Department of Chemical and Biomolecular Engineering Institute of Emergent MaterialsSogang UniversitySeoul 04107Korea Department of Cogno-Mechatronics Engineering College of Nanoscience and NanotechnologyPusan National UniversityBusan 46241Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoul 08826Korea School of Chemical Engineering and Material Science Chung-Ang UniversitySeoul 06974Korea

The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to achieve a self-standing electrode,composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters(ACP/Ru_(SAC+C))via acid activation,immersion,and high-temperature *** initio molecular dynamics(AIMD)calculations are employed to gain a more profound understanding of the impact of acid activation on carbon ***,the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy(AC-STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS).Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect,tuning the electronic structure and thereby significantly enhancing their catalytic ***,the ACP/Ru_(SAC+C)exhibits a remarkable turnover frequency(TOF)of 18 s^(−1)and an exceptional mass activity(MA)of 2.2 A mg^(−1),surpassing the performance of conventional Pt *** self-standing electrode,featuring harmoniously coexisting Ru states,stands out as a prospective choice for advancing HER catalysts,enhancing energy efficiency,productivity,and selectivity.

关键词： electrocatalysis electronic coupling effect hydrogen evolution reaction selfstanding electrode

Crystallographically vacancy‐induced MOF nanosheet as rational single‐atom support for accelerating CO_(2)electroreduction to CO

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Carbon Energy 2024年第8期6卷 49-62页

作者： jin hyuk Cho Joonhee Ma Chaehyeon Lee jin Wook Lim Youngho Kim Ho Yeon Jang Jaehyun Kim Myung‐gi Seo Youngheon choi Youn Jeong Jang Sang Hyun Ahn Ho Won Jang Seoin Back Jong‐Lam Lee Soo Young Kim Department of Materials Science and Engineering Korea UniversitySeoulRepublic of Korea Department of Chemical and Biomolecular Engineering Sogang UniversitySeoulRepublic of Korea Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)PohangRepublic of Korea Department of Materials Science and Engineering Research Institute of Advanced MaterialsSeoul National UniversitySeoulRepublic of Korea Lotte Chemical R&D Center DaejeonRepublic of Korea Department of Chemical Engineering Hanyang UniversitySeoulRepublic of Korea School of Chemical Engineering and Material Science Chung‐Ang UniversitySeoulRepublic of Korea

To attain a circular carbon economy and resolve CO_(2)electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic *** SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal *** study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100%for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h−1,validating their intrinsic catalytic *** results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during ***,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*)preadsorbed sites as initial states was possible and provided valuable insights.

关键词： 2‐dimensional material carbon dioxide reduction metal-organic frameworks single‐atom catalysts vacancy sites

Real-Time Tunable Gas Sensing Platform Based on SnO_(2) Nanoparticles Activated by Blue Micro-Light-Emitting Diodes

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Nano-Micro Letters 2024年第12期16卷 103-119页

作者： Gi Baek Nam Jung-El Ryu Tae Hoon Eom Seung Ju Kim Jun Min Suh Seungmin Lee Sungkyun choi Cheon Woo Moon Seon Ju Park Soo Min Lee Byungsoo Kim Sung hyuk Park jin Wook Yang Sangjin Min Sohyeon Park Sung Hwan Cho hyuk jin Kim Sang Eon Jun Tae Hyung Lee Yeong Jae Kim Jae Young Kim Young Joon Hong Jong-In Shim Hyung-Gi Byun Yongjo Park Inkyu Park Sang-Wan Ryu Ho Won Jang Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea Research Laboratory of Electronics Department of Mechanical EngineeringMassachusetts Institute of TechnologyCambridgeMA 02139USA Ming Hsieh Department of Electrical and Computer Engineering University of Southern CaliforniaLos AngelesCA 90089USA Department of Display Materials Engineering Soonchunhyang UniversityAsan 31538Republic of Korea Department of Photonics and Nanoelectronics BK21 FOUR ERICA-ACE CenterHanyang University ERICAAnsan 15588Republic of Korea Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Electronics Information and Communication EngineeringKangwon National UniversitySamcheok 25913Republic of Korea Advance Institute of Convergence Technology Seoul National UniversitySuwon 16229Republic of Korea Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Physics Chonnam National UniversityGwangju 500-757Republic of Korea

Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power ***,despite these benefits,challenges still exist such as a limited range of detectable gases and slow *** this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power *** optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain ***,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)*** noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and ***-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.

关键词： Micro-LED Gas sensor array Low power consumption Metal decoration Real-time detection

Impact of high-resolution HLA matching on outcomes of unrelated donor hematopoietic stem cell transplantation

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Impact of high-resolution HLA matching on outcomes of unrela...