논문현황

INSTITUTE FOR ADVANCED ENGINEERING

융합소재연구센터 Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis

· 저자

Basudev Swain, 신동윤, 주소영, 안낙균, 이찬기, 윤진호


Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100 nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously.


융합소재연구센터 Hydridation and oxidation behaviors of tantalum hydride during milling process

· 저자

이지은, 윤진호, 이찬기, 박지환, 박일규


The effect of ethanol addition during milling on the milling performances of Ta-hydride powders was investigated for hydride and dehydride processes during Ta recycling process. As the Ta-hydride was milled in a conventional dry atmosphere, Ta2O was dominantly formed due to the increased temperature of the Ta-hydride pieces because they were rubbed against each other and crushed by the ring mill system. However, with the addition of ethanol solvent, the ratio of the Ta2H phase increased compared to the Ta2O phase, and the size of the powders reduced and became more uniform. These were attributed to the enhanced hydride formation and reduced contact between the Ta-hydride powders and air by wetting them. Therefore, an optimum amount of ethanol addition and milling time can enhance the formation of additional Ta-hydrides, while preventing oxidation during milling.


융합소재연구센터 Enhanced Tantalum Hydride Formation by the Catalytic Effect of Tungsten for Hydrogen Dissociation

· 저자

이지은, 윤진호, 이찬기, 박지환, 박일규


We investigated enhanced tantalum (Ta) hydride formation by using the catalytic effect of tungsten (W) to reduce the hydrogen dissociation energy. Ta turning scrap was hydrated at various temperatures by using a W crucible and conventional Al2O3 crucible, and the structural and chemical properties of the hydrated powders were compared. Structural investigation by X-ray diffraction and chemical analysis using an oxygen–nitrogen–hydrogen determinator showed that the Ta hydride was formed at temperatures lower than 500 °C, while the dehydride formation process occurs at temperatures higher than 600 °C in conventional Al2O3 crucibles. However, when the W crucible is used, the hydrogen incorporation into the Ta lattice was enhanced at both low and high temperatures. This enhancement was attributed to the reduced energy of dissociation of H2 into mono-atomic H because of the catalytic effect of W, finally resulting in enhanced Ta hydride formation.


융합소재연구센터 Development of High-Strength Glass–Ceramic Materials by Utilization of Slag Discharged from Steel-Making Industry in Korea

· 저자

신동윤, 이덕희, 윤미정, 박현서, 서성보, 윤진호


Every year 25 million tons of slag is generated as an industrial by-product by the steel-making industry in Korea. Using slag to manufacture high-strength glass–ceramic materials is increasingly becoming a feasible option, and recently several types of slag have been used in combination to manufacture glass–ceramic materials such as basalt-based glass–ceramics. Glass–ceramic materials with two different chemical compositions were prepared using Fe–Ni slag, basic oxygen furnace slag, dephosphorization slag, and fly ash by melting and casting and a subsequent heat treatment. X-ray diffraction analyses confirmed that clinopyroxene and CaAl2SiO8 were the primary phases in the formed glass–ceramics, while thermogravimetry and differential thermal analyses showed that their glass-transition points were 709–724 °C and crystallization temperatures were 888–918 °C. The morphologies and constituent components were also examined using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The stable phases were calculated as functions of the temperature using FactSage. Finally, the compressive strength, Vickers hardness, and wear rate values of the glass–ceramics were evaluated in order to elucidate their physical properties.


융합소재연구센터 Electrochemical Performances of Li2MnSiO4 Cathodes Synthesized by Mechanical Alloying Process

· 저자

진연호, 박경수, 강이승, 김범성, 홍현선


We report the fabrication and electrochemical properties of Li2MnSiO4 powders produced by various solid-state reactions, such as ball-, attrition-, and bead-milling. Li2MnSiO4 powders prepared by bead-milling had the smallest particle sizes (∼100 nm) and the largest amount of surface carbon (∼20 wt%), which were produced by adding sucrose during milling process. The surface carbon layer can improve electronic/ionic conductivity of Li2MnSiO4 as cathode material for lithium ion battery. As expected, the bead-milled Li2MnSiO4 powder electrode showed the best electrochemical performance of the electrode materials obtained by the various solid-state reactions. This is attributed to the small particle size and facile electronic transport through the conductive carbon layer on each Li2MnSiO4 particle.


융합소재연구센터 Recycling of GaN, a Refractory eWaste Material: Understanding the Chemical Thermodynamics

· 저자

Basudev Swain, Chinmayee Mishra, 이근재, 홍현선, 박경수, 이찬기


South Korea is a major producer of light‐emitting diode (LED) material, contributing 31% of total LED demand worldwide, and also a major consumer of electronic devices. During manufacturing and after end of life (EOL) of the consumer electronics, significant amount of GaN‐bearing waste is being generated. As the Republic of Korea depends upon the import of all mineral commodities, under the national policy of securing a stable supply, much attention has been paid to the notion of “urban mining.” The stringent international environmental directive for recycling of waste electrical and electronic equipment (WEEE), United Nations Environment Programme (UNEP) E‐Waste Management goal, restriction of the use of hazardous substances in EEE (RoHS), and extended producer responsibility (EPR) have made recycling an important responsibility. Recovery of the gallium from GaN‐bearing waste can be a promising feasible option; simultaneously from the waste, the wealth can be generated. As GaN is a refractory material, which is hard to leach in the recovery process, hence, needs a chemical pretreatment. In this study, thermodynamics of GaN oxidation and oxidative roasting using Na2CO3 has been studied. Thermodynamic feasibility for leaching of oxidized GaN either through acidic leaching or through alkali leaching has been explored.


융합소재연구센터 Synthesis of Flower‐like Cu3[MoO4]2O from Cu3(MoO4)2(OH)2 and Its Application for Lithium‐Ion Batteries: Structure‐Electrochemical Property Relationships

· 저자

Basudev Swain, 이덕희, 김준식, 이찬기, 김동완, 박경수


Flower‐like Cu3[MoO4]2O microspheres have been synthesized by using a sequential process from lindgrenite (Cu3(MoO4)2(OH)2). Lindgrenite nanoflowers were synthesized through a simpler route by using an aqueous chemical precipitation technique at room temperature without any surfactants or template. Subsequently, 3D flower‐like Cu3[MoO4]2O microspheres have been synthesized by annealing at 300 °C for 2 h from lindgrenite (Cu3(MoO4)2(OH)2). From the XRD pattern, FTIR spectrum, SEM and TEM analysis, flower‐like Cu3[MoO4]2O (ca. 5 μm) microspheres have been obtained, which were assembled from 3–4 nm thick nanosheets with an orthorhombic structure. Application of 3D flower‐like microspheres as an anode material for lithium‐ion batteries (LIBs) has been investigated and the possible electrochemical mechanism is analyzed. Electrochemical characterization of the Cu3[MoO4]2O nanoflowers as an anode material for LIBs has exhibited good cycle stability and a high coulombic efficiency during operation. The electrochemical activity was attributed to the unique structure of the Cu3[MoO4]2O microspheres, which provide more active sites for Li‐ion storage as well as a reduced transfer resistance. This work has explored a simple synthesis strategy for the synthesis of flower‐like Cu3[MoO4]2O microspheres without templates, additives, or surfactants, which exhibit a basis for not only high electrochemical performance in reversible Li storage, but also cycle stability.


융합소재연구센터 Enhanced electrochemical performance of carbon-coated Li2MnSiO4 nanoparticles synthesized by tartaric acid-assisted sol–gel process

· 저자

박경수, 진연호, 강이승, 이광희, 이남희, 김동완, 홍현선


A tartaric acid-assisted sol–gel process was used to synthesize Li2MnSiO4 (SG-LMS) nanopowders with orthorhombic structures (Pmn21 space group). The Li-active SG-LMS nanoparticles were fully surrounded by a conducting amorphous carbon layer/matrix that was formed by carbonization of the tartaric acid during post-annealing of the dry gel. The SG-LMS electrode exhibited higher specific capacity and superior cycle retention as compared to the LMS electrode prepared by a conventional solid-state reaction. Such high electrochemical performance originated from the presence of a high-purity phase, a large surface area, and an efficient electron transport path facilitated by the conductive carbon coating of the SG-LMS electrode.


융합소재연구센터 Recycling of waste automotive laminated glass and valorization of polyvinyl butyral through mechanochemical separation

· 저자

Basudev Swain, 박재량, 신동윤, 박경수, 홍명환, 이찬기


Due to strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility polyvinyl butyral (PVB) resin films are commonly used in the automotive and architectural application as a protective interlayer in the laminated glass. Worldwide million tons of PVB waste generated from end-of-life automotive associated with various environmental issues. Stringent environmental directive, higher land cost eliminates land filling option, needs a study, we have developed a mechanochemical separation process to separate PVB resins from glass and characterized the separated PVB through various techniques, i.e., scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). Commercial nonionic surfactants D201 used for the mechanochemical separation purpose. Through parameter optimization following conditions are considered to be the optimum condition; 30 vol% D201, stirring speed of 400 rpm, 35 °C temperature, operation time 1 h, and dilute D201 volume to waste automotive laminated glass weight ratio of ≈25. The technology developed in our laboratory is sustainable, environmentally friendly, techno-economical feasible process, capable of mass production (recycling).


융합소재연구센터 Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

· 저자

Basudev Swain, Chinmayee Mishra, 강이승, 박경수, 이찬기, 홍현선


Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching.


융합소재연구센터 Recycling of metal-organic chemical vapor deposition waste of GaN based power device and LED industry by acidic leaching: Process optimization and kinetics study

· 저자

Basudev Swain, Chinmayee Mishra, 강이승, 박경수, 이찬기, 홍현선, 박정진


Recovery of metal values from GaN, a metal-organic chemical vapor deposition (MOCVD) waste of GaN based power device and LED industry is investigated by acidic leaching. Leaching kinetics of gallium rich MOCVD waste is studied and the process is optimized. The gallium rich waste MOCVD dust is characterized by XRD and ICP-AES analysis followed by aqua regia digestion. Different mineral acids are used to find out the best lixiviant for selective leaching of the gallium and indium. Concentrated HCl is relatively better lixiviant having reasonably faster kinetic and better leaching efficiency. Various leaching process parameters like effect of acidity, pulp density, temperature and concentration of catalyst on the leaching efficiency of gallium and indium are investigated. Reasonably, 4 M HCl, a pulp density of 50 g/L, 100 °C and stirring rate of 400 rpm are the effective optimum condition for quantitative leaching of gallium and indium.


융합소재연구센터 Synthesis of Cu3(MoO4)2(OH)2 nanostructures by simple aqueous precipitation: understanding the fundamental chemistry and growth mechanism

· 저자

Basudev Swain, 이덕희, 박재량, 이찬기, 이근재, 김동완, 박경수


Lindgrenite (Cu3(MoO4)2(OH)2) nanoflowers were synthesized through the simplest possible route by an aqueous chemical precipitation technique at room temperature without using any surfactants, template, expensive chemicals, complex instrumentation or tedious multistage synthesis process. Their morphology, structure, thermal properties, surface area, synthesis chemistry, and structural and growth mechanisms involved in the synthesis process were analyzed. Using XRD, FE-SEM, HR-TEM and FT-IR spectroscopy, their structure and morphology were analyzed. The thermal stability, surface area and porosity of the Cu3(MoO4)2(OH)2 nanoflowers were analyzed by TGA and BET. XRD analysis showed that the Cu3(MoO4)2(OH)2 nanoflowers have a pure monoclinic structure. The morphological analysis showed that the Cu3(MoO4)2(OH)2 nanoflowers are ∼10 μm in size, which are formed from self-assembly of thin nanosheets with a thickness of ∼20 nm. TGA indicated that the Cu3(MoO4)2(OH)2 nanoflowers are stable materials up to 328 °C and the isotherm from BET analysis indicated that the Cu3(MoO4)2(OH)2 nanoflowers are non-porous materials. The BET surface area of the synthesized Cu3(MoO4)2(OH)2 nanoflowers was found to be 21.357 m2 g−1. Moreover, the effects of the pH value and reaction time on the morphology of the Cu3(MoO4)2(OH)2 nanoflowers were studied and their optimization was performed. The results of the optimization study indicated that the reaction time and pH are two important parameters influencing the nucleation, growth, morphology, and synthesis mechanism. These flower-shaped Cu3(MoO4)2(OH)2 nanostructures are promising precursors for preparing molybdenum oxide materials which have various applications and can be synthesized in a very simple one-pot reaction system using commonly available chemicals without using a complex route.


융합소재연구센터 Synthesis of cosmetic grade TiO2-SiO2 core-shell powder from mechanically milled TiO2 nanopowder for commercial mass production

· 저자

Basudev Swain, 박재량, 박경수, 이찬기


TiO2 nanoparticles as an active sunscreen ingredient generate reactive oxygen species (ROS) upon UVA irradiation which is cytotoxic, genotoxic and potential to damage the DNA. The health concern and potential risks from TiO2 can be mitigated by shielding the particles through the suitable coating. Considering the advantages of SiO2, SiO2 coated TiO2 nanoparticles can be a potential material which can replace TiO2 for thickening, whitening, lubricating, and sunscreen ingredient in cosmetics. This article reports the synthesis of cosmetic grade TiO2-SiO2 core-shell nanopowder from mechanically milled TiO2 nanopowder for commercial mass production. From commercial TiO2 nanopowder was fabricated through size reduction by nanoset milling. Followed by the fabricated TiO2 nanopowder coated with SiO2 through sol-gel technique. A suitable optimum condition was explored for cosmetic grade TiO2-SiO2 core-shell nanopowder. Various physical properties and optical properties were analyzed. Synthesized of cosmetic grade TiO2-SiO2 core-shell nanopowder found to be at 100 nm size, with a homogeneous SiO2 coating having UVA protection factor 39 and sun protection factor (SPF) is 42. From the size, safety, and SPF perspective it can be an excellent cosmetic grade powder and from process simplicity perspective it can be commercially viable.


융합소재연구센터 One-pot wet chemical synthesis of fluorine-containing TiO2 nanoparticles with enhanced photocatalytic activity

· 저자

이덕희, Basudev Swain, 신동윤, 안낙균, 박재량, 박경수


Two types of TiO2 nanoparticles: i) fluorine-containing TiO2 (F-TiO2) and ii) fluorine-free TiO2 (H-TiO2) nanoparticles, were prepared through a simple, scalable wet-chemical synthesis process, and a comparative study of their photocatalytic properties was conducted. This facile process begins with a one-pot precipitation process at 90 °C, followed by heat treatment at 600 °C for 1 h in air, resulting in hierarchical, sphere-like, mesoporous structures composed of primary nanoparticles. The microstructural features and crystallographic structures of both types of nanoparticles were systematically investigated by X-ray diffraction, thermogravimetric/differential thermal analysis, X-ray photoelectron spectroscopy, N2 physical adsorption-desorption, field emission scanning electron microscopy, and transmission electron microscopy analyses. The photocatalytic activities were also evaluated by measuring the degradation of MB. The F-TiO2 nanoparticles showed enhanced photocatalytic activity compared to H-TiO2, which can be attributed to adsorbed fluorine on the surface which leads to various positive effects on the photocatalytic degradation reactions.


플랜트공정개발센터 알카라인 연료전지 가스확산층 내구성 향상을 위한 초발수 코팅 최적화 연구

· 저자

엄성현,김숭연 서민혜


본 연구에서는 알카라인 연료전지 환원극 가스확산층에 내열화학성이 우수한 초발수 성능을 부여하기 위하여 PDMS 코팅 공정을 최적화하였다. 성격이 상이한 두 개의 상용 가스확산층을 선택하였으며, 소재의 열적 안정성을 검토하여 코팅 온도를 최적화하고, PDMS 점도를 제어하여 코팅 균일성을 확보하고자 하였다. PDMS 전구체의 점도와 관계없이 200 ℃ 부근에서 코팅하게 되면 모든 확산층 표면에서 높은 초발수 성능을 나타내었다. 가혹실험 조건에서 초발수 성능 변화를 측정한 결과 1000 CS PDMS를 이용하여 28BC 가스확산층에 코팅한 경우가 가장 높은 내구성을 나타내었다.


플랜트공정개발센터 온도조절 화학기상증착법을 활용한 대용량 허니컴 구조촉매 제조 연구

· 저자

엄성현,서민혜,김숭연,김영독


본 연구에서는 대용량 구조 촉매의 제조 및 활용 가능성을 확인하고자 셀 밀도가 높은 세라믹 허니컴 구조체와 온도조절 화학기상증착법을 활용하여 촉매를 제조하고 건식 개질 반응에 대한 촉매 활성을 평가하였다. 셀 밀도 600 cpsi 코디어라이트 허니컴(CDR)을 대상으로 니켈을 코팅한 NiO/CDR 촉매는 코팅 조건과 시간을 조절함으로써 허니컴 구 조체 셀 내부까지 충분한 균일 증착이 가능하였다, 800 ℃, 공간속도 10,000 h-1과 CH4와 CO2를 1 : 1로 주입한 조건에서 CH4는 약 83%, CO2는 약 90% 이상의 우수한 전환율을 보여 건식 개질 반응에 효과적으로 적용이 가능하다는 것을 확인하였다. 이 결과를 토대로 대면적, 대용량 촉매 제조 시 온도조절 화학기상증착법이 매우 유용하게 활용될 수 있음을 확인하였다.


플랜트공정개발센터 산화철 허니컴 구조 촉매를 활용한 일산화탄소 저온 산화반응 연구

· 저자

엄성현,이동헌


코디어라이트 허니컴 표면에 알루미나 워시코트 지지체를 형성시키고 비교적 단순한 건식 코팅 공정으로 산화철 촉 매를 코팅함으로써 실제 환경에 효과적으로 적용이 가능한 모노리스 구조 촉매를 제조하였다. 허니컴 통로 벽 구석으로 형성된 워시코트 알루미나 미세 기공으로 균일하게 코팅된 산화철 촉매를 확인하였으며, 일산화탄소 산화 반응에 적용하기 위하여 산화철 촉매의 열처리 효과를 검증하였다. 350 ℃ 부근에서 처리한 산화철 촉매가 가장 우수한 촉매 성능을 발휘하였고, 200 ℃ 이상의 온도 영역에서 100% 전환율을 나타내었다.


플랜트공정개발센터 Highly stable barium zirconate supported nickel oxide catalyst for dry reforming of methane: From powders toward shaped catalysts

· 저자

엄성현,서민혜,김숭연


We report the barium zirconate supported NiOx catalysts (NiOx/BZO) for dry reforming of methane and feasibility test for their industrial application by using temperature-regulated chemical vapor deposition together with extrusion. Nickel oxide nanoparticles are well deposited and dispersed on BZO powders as well as structures in a gear form, showing high catalytic activity and extraordinary stability even at relatively lower temperature and higher space velocity. The NiOx/BZO catalyst are highly coke resistant for 50 h operation with almost negligible agglomeration of NiOx nanoparticles. Judging from XPS and high ion conducting properties of BZO supports, the eOH or eO species are expected to play an important role in promoting the self-decoking of surface carbon species to form CO and CO2.


지능기계시스템센터 Acoustic emission characteristics of stress corrosion cracks in a type 304 stainless steel tube

· 저자

Woonggi Hwang, Seunggi Bae, Jaeseong Kim, Sungsik Kang, Nogwon Kwag, Boyoung Lee


Acoustic emission (AE) is one of the promising methods for detecting the formation of stress corrosion cracks (SCCs) in laboratory tests. This method has the advantage of online inspection. Some studies have been conducted to investigate the characteristics of AE parameters during SCC propagation. However, it is difficult to classify the distinct features of SCC behavior. Because the previous studies were performed on slow strain rate test or compact tension specimens, it is difficult to make certain correlations between AE signals and actual SCC behavior in real tube-type specimens. In this study, the specimen was a AISI 304 stainless steel tube widely applied in the nuclear industry, and an accelerated test was conducted at high temperature and pressure with a corrosive environmental condition. The study result indicated that intense AE signals were mainly detected in the elastic deformation region, and a good correlation was observed between AE activity and crack growth. By contrast, the behavior of accumulated counts was divided into four regions. According to the waveform analysis, a specific waveform pattern was observed during SCC development. It is suggested that AE can be used to detect and monitor SCC initiation and propagation in actual tubes.


지능기계시스템센터 The Effect of Welding Residual Stress for Making Artificial Stress Corrosion Crack in the STS 304 Pipe

· 저자

Jae-Seong Kim, Bo-Young Lee, Woong-Gi Hwang and Sung-Sik Kang


The stress corrosion crack is one of the fracture phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and grown especially in dissimilar weldment of primary loop components. In particular, stress corrosion crack usually occurs when the following three factors exist at the same time: susceptible material, corrosive environment, and tensile stress (residual stress included). Thus, residual stress becomes a critical factor for stress corrosion crack when it is difficult to improve the material corrosivity of the components and their environment under operating conditions. In this study, stress corrosion cracks were artificially produced on STS 304 pipe itself by control of welding residual stress. We used the instrumented indentation technique and 3D FEM analysis (using ANSYS 12) to evaluate the residual stress values in the GTAW area. We used the custom-made device for fabricating the stress corrosion crack in the inner STS 304 pipe wall. As the result of both FEM analysis and experiment, the stress corrosion crack was quickly generated and could be reproduced, and it could be controlled by welding residual stress