• 제목/요약/키워드: Leaching material

검색결과 237건 처리시간 0.024초

Corrosion behavior and mechanism of CLAM and 316L steels in flowing Pb-17Li alloy under magnetic field

  • Xiao, Zunqi;Liu, Jing;Jiang, Zhizhong;Luo, Lin;Huang, Qunying
    • Nuclear Engineering and Technology
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    • 제54권6호
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    • pp.1962-1971
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    • 2022
  • The liquid lead-lithium (Pb-17Li) blanket has many applications in fusion reactors due to its good tritium breeding performance, high heat transfer efficiency and safety. The compatibility of liquid Pb-17Li alloy with the structural material of blanket under magnetic field is one of the concerns. In this study, corrosion experiments China low activation martensitic (CLAM) steel and 316L steel were carried out in a forced convection Pb-17Li loop under 1.0 T magnetic field at 480 ℃ for 1000 h. The corrosion results on 316L steel showed the characteristic with a superficial porous layer resulted from selective leaching of high-soluble alloy elements and subsequent phase transformation from austenitic matrix to ferritic phase. Then the porous layers were eroded by high-velocity jet fluid. The main corrosion mechanism of CLAM steel was selective dissolution-base corrosion attack on the microstructure boundary regions and exclusively on high residual stress areas. CLAM steel performed a better corrosion resistance than that of 316L steel. The high Ni dissolution rate and the erosion of corroded layers are the main causes for the severe corrosion of 316L steel.

MLCC에서 회수된 산화니켈 분말의 전기방사공정을 통한 나노와이어 제조 (Fabrication of Nanowire by Electrospinning Process Using Nickel Oxide Particle Recovered from MLCC )

  • 신해인;배종원;강민수;이근재
    • 한국분말재료학회지
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    • 제30권6호
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    • pp.502-508
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    • 2023
  • With the increasing demand for electronic products, the amount of multilayer ceramic capacitor (MLCC) waste has also increased. Recycling technology has recently gained attention because it can simultaneously address raw material supply and waste disposal issues. However, research on recovering valuable metals from MLCCs and converting the recovered metals into high-value-added materials remains insufficient. Herein, we describe an electrospinning (E-spinning) process to recover nickel from MLCCs and modulate the morphology of the recovered nickel oxide particles. The nickel oxalate powder was recovered using organic acid leaching and precipitation. Nickel oxide nanoparticles were prepared via heat treatment and ultrasonic milling. A mixture of nickel oxide particles and polyvinylpyrrolidone (PVP) was used as the E-spinning solution. A PVP/NiO nanowire composite was fabricated via E-spinning, and a nickel oxide nanowire with a network structure was manufactured through calcination. The nanowire diameters and morphologies are discussed based on the nickel oxide content in the E-spinning solution.

NCM(Li[Ni,Co,Mn]O2)계 폐 리튬이차전지로부터 NiSO4의 회수와 이를 이용한 LiNiO2 제조 및 전기화학적 특성 (Fabrication of LiNiO2 using NiSO4 Recovered from NCM (Li[Ni,Co,Mn]O2) Secondary Battery Scraps and Its Electrochemical Properties)

  • 곽용규;김미소;김유영;최임식;박동규;안인섭;조권구
    • 한국분말재료학회지
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    • 제21권4호
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    • pp.286-293
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    • 2014
  • The electrochemical properties of cells assembled with the $LiNiO_2$ (LNO) recycled from cathode materials of waste lithium secondary batteries ($Li[Ni,Co,Mn]O_2$), were evaluated in this study. The leaching, neutralization and solvent extraction process were applied to produce high-purity $NiSO_4$ solution from waste lithium secondary batteries. High-purity NiO powder was then fabricated by the heat-treatment and mixing of the $NiSO_4$ solution and $H_2C_2O_4$. Finally, $LiNiO_2$ as a cathode material for lithium ion secondary batteries was synthesized by heat treatment and mixing of the NiO and $Li_2CO_3$ powders. We assembled the cells using the $LiNiO_2$ powders and evaluated the electrochemical properties. Subsequently, we evaluated the recycling possibility of the cathode materials for waste lithium secondary battery using the processes applied in this work.

토양중의 중금속 연속추출방법과 사례연구 (Sequential Extraction of Heavy Metals in Soils and A Case Study)

  • 정명채
    • 자원환경지질
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    • 제27권5호
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    • pp.469-477
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    • 1994
  • Many researchers have investigated most representative sequential extraction method using various reagents for determining the chemical forms of metals in soils and sediments. In this paper, a newly modified method for sequential extraction scheme based on Tessier's method by Environmental Geochemistry Research, Centre for Environmental Technology, Imperial College, was introduced and examined. In comparison with Tessier's method, originally designed for sediment analysis by Atomic Absorption Spectrophotometry (AAS), the sequential extraction scheme has been developed for the multi-element analysis by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The partitioning of particulate trace elements was classified into five fractions: (i) exchangeable, (ii) bound to carbonates or specially adsorbed, (iii) bound to Fe and Mn oxides, (iv) bound to organic matter and sulphides and (v) residuals. The experimental results of the pilot study for in-house reference material (HRM2) and certified international standard reference material (SRM2711) using the modified method showed not only reasonable precision and accuracy but also acceptable overall recovery rates. In addition, mine dump soils sampled in the Dalsung Cu-W mine, Korea were prepared and sequentially extracted using the method. Most of Cu was bound to organic matter/sulphides and residual fractions. The dominant fraction of soil Pb and Zn in the study area was found in the residuals. The fraction of Cd showed a wide variation between samples and could be found bound to the carbonates or specially adsorbed, oxides, organic fraction and residuals. The recovery rates of Cd, however, were poor due to relatively low Cd concentrations in soils. The heavy metals in these mine dumps appear to be in the more inert forms and should not be readily bioavailable. The soils, however, had very low pH values (average 4.1) and had sandy textures; consequently, rapid infiltration of rainfall may increase leaching of Zn and Cd which were found to be around 5 to 10% of the exchangeable fraction. As a result of the investigation of this study, it has been strongly recommended that these mine waste materials should still be considered a significant contaminant source and will need environmental remediation to prevent pollutants from being released into the environment.

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자동차 브레이크 마찰재용 비침상형 육티탄산칼륨의 합성 연구 (Synthesis of Potassium Hexatitanate with Non-Fibrous Shape as a Raw Material for Friction Material in Brake System)

  • 이정주;이나리;피재환;김종영;김정주
    • 한국재료학회지
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    • 제27권3호
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    • pp.132-136
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    • 2017
  • We synthesized potassium hexatitanate, ($K_2Ti_6O_{13}$, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate ($K_2Ti_4O_9$, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ${\sim}920^{\circ}C$. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at $850^{\circ}C$, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.

$LiCoO_2$의 재합성시(再合成時) 전극특성(電極特性)에 미치는 탄소(炭素)의 영향(影響) (Effect of Carbon on Electrode Characteristics of $LiCoO_2$ Resynthesis)

  • 이철경;박정길;손정수
    • 자원리싸이클링
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    • 제16권6호
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    • pp.10-19
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    • 2007
  • 폐리튬이온전지의 리싸이클링을 위하여 폐전지의 기계적 처리에 의한 Co의 농축과 습식처리에 의한 Co의 회수기술이 개발되었다. 전 연구에서는 폐전지 리싸이클링의 부가가치를 향상시키기 위하여 Co 농축 침출액으로부터 양극활물질을 재합성하는 공정으로 citrate precursor combustion법을 제안하고 가능성을 확인하였다. 기존의 전극제조 공정에서는 활물질인 $LiCoO_2$와 첨가제인 탄소의 비중 및 크기 차이로 균일한 혼합이 이루어지지 않으므로 충방전 용량이 이론용량에 비하여 매우 낮고 또한 싸이클이 반복될수록 용량이 크게 감소하는 경향을 보였다. 본 연구에서는 합성된 $LiCoO_2$ 전극특성을 향상시키는 일환으로 합성공정의 개선을 통하여 초미립 $LiCoO_2$을 합성하였으며, 탄소 첨가시 혼합법의 개선에 의하여 우수한 충방전 특성을 갖는 리튬전지용 양극을 개발하였다.

Socket preservation using eggshell-derived nanohydroxyapatite with platelet-rich fibrin as a barrier membrane: a new technique

  • Kattimani, Vivekanand Sabanna;Lingamaneni, Krishna Prasad;Kreedapathi, Girija Easwaradas;Kattappagari, Kiran Kumar
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • 제45권6호
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    • pp.332-342
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    • 2019
  • Objectives: Socket grafting is vital to prevent bone resorption after tooth extraction. Several techniques to prevent resorption have been described, and various bone graft substitutes have been developed and used with varying success. We conducted this pilot study to evaluate the performance of nanohydroxyapatite (nHA) derived from chicken eggshells in socket preservation. Materials and Methods: This was a prospective, single center, outcome assessor-blinded evaluation of 23 sockets (11 patients) grafted with nHA and covered with platelet-rich fibrin (PRF) membrane as a barrier. Bone width and radiographic bone density were measured using digital radiographs at 1, 12, and 24 weeks post-procedure. Postoperative histomorphometric and micro-computed tomography (CT) evaluation were performed. The study protocol was approved by the Institutional Ethics Committee. Results: All patients had uneventful wound healing without graft material displacement or leaching despite partial exposure of the grafted socket. Tissue re-epithelialized with thick gingival biotype (>3 mm). Width of the bone was maintained and radiographic density increased significantly with a trabecular pattern (73.91% of sockets) within 12 weeks. Histomorphometric analysis showed 56.52% Grade 3 bone formation and micro-CT analysis revealed newly formed bone with interconnecting trabeculae. Conclusion: Use of a PRF membrane with nHA resulted in good bone regeneration in sockets. Use of a PRF membrane prevents periosteal-releasing incisions for primary closure, thereby facilitating the preservation of keratinized mucosa and gingival architecture. This technique, which uses eggshell-derived nHA and PRF membrane from the patient's own blood, is innovative and is free of disease transfer risks. nHA is a promising economic bone graft substitute for bone regeneration and reconstruction because of the abundant availability of eggshell waste as a raw material.

알칼리성 실리카졸 지반주입재의 특성에 관한 연구 (A Study on the Characteristics of Alkali Silica Sol Grouting Material)

  • 조영훈;김찬기;천병식
    • 한국지반환경공학회 논문집
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    • 제12권4호
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    • pp.17-24
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    • 2011
  • 차수 및 지반안정을 목적으로 규산나트륨을 사용한 기존의 알칼리성 물유리계 약액주입공법은 주입 후 시간경과에 따라 지하수에 의해 주입고결체로부터 알칼리성분의 용탈이 진행되어 내구성이 약해지고 지하수를 오염시키는 문제점이 있다. 따라서 본 연구에서는 규산나트륨 주입재의 문제점을 보완하기 위해 개발된 알칼리성 실리카졸 지반주입재의 효과를 규명하는 데에 그 목적이 있다. 연구비교대상으로는 규산나트륨 주입재와 알칼리성 실리카졸 주입재로 하였다. 규산나트륨과 알칼리성 실리카졸 용액에 대하여 보통 포틀랜트 시멘트와 고로 슬래그 시멘트를 각각 배합하여 총 4가지의 Case로 나누어 공시체를 제작하여 시험을 실시하였다. 재령에 따른 일축압축강도 시험을 실시하였고, 환경영향성평가를 위하여 어독성시험과 pH시험을 실시하여 비교 및 분석을 하였다. 본 연구를 통해 고로 슬래그 시멘트를 배합한 알칼리성 실리카졸 지반주입재가 우수한 강도와 친환경성을 가지고 있는 것으로 나타났다.

RAW 264.7 세포에서 레드비트의 항산화 및 항염증 등의 생리활성 연구 (The Study on the Physiological Activities of Beta vulgaris such as Antioxidant and Anti-inflammatory in RAW 264.7 cells)

  • 지중구
    • 한국응용과학기술학회지
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    • 제38권1호
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    • pp.309-317
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    • 2021
  • 본 연구는 침출차 원료로 레드비트를 활용하기 위해서 세포독성, 항염증 및 항산화 등의 활성을 조사하고자 설계되었다. 항산화 효능은 DPPH 및 ABTS 라디컬 소거 활성을 분석하여 평가하였다. RAW 264.7 세포를 통해 MTT 분석으로 세포 생존율을 평가하고 LPS로 유도하여 활성산소종과 염증매개체(일산화질소, TNF-α, IL-6 등)의 생성량을 확인하였다. 그 결과, DPPH 및 ABTS 라디컬 소거활성은 농도 의존적으로 증가하였으며, 모든 농도에서 세포독성이 없음을 확인하였다. 또한, LPS로 유도한 RAW 264.7 세포에서 활성산소종(ROS)과 일산화질소(NO), IL-6, TNF-α 생성량을 유의적으로 감소시켰다. 따라서 이러한 결과는 레드비트가 안전한 항산화 및 항염증 효과를 가진 침출차의 원료로서 높은 잠재력을 가지고 있음을 시사한다.

교각에 설치된 사석보호공의 침하량 산정식 도출에 관한 실험 연구 (An Experimental Study to develope the Subsidence Equation for Riprap Protection around the Pier)

  • 지운;여운광;이원민;강준구
    • 대한토목학회논문집
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    • 제29권1B호
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    • pp.63-71
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    • 2009
  • 교각 세굴 방지를 위해 사석보호공을 설치하는 경우 하상의 유사이탈로 인한 보호공의 침하현상이 발생할 수 있으며 따라서 사석층과 하상 사이에 필터층의 설치가 반드시 필요하다. 하지만 국내의 명확하지 않은 필터설치 기준과 설치를 위한 기술적 어려움 그리고 고가의 공사비와 같은 문제점으로 인해 현장에서는 필터 없는 사석보호공을 주로 시공하고 있다. 이에 본 연구는 다양한 조건의 사석 포설두께, 접근 유속, 사석과 하상토의 입경을 갖는 수리실험을 통해 필터층이 없는 사석보호공의 침하량을 정량적으로 측정 및 분석하였으며 실험 결과, 접근유속이 증가할수록, 하상토의 입경이나 포설두께가 감소 할수록 최대침하량은 증가하는 양상을 보였고 일정 시간 후에는 침하량이 최대값에 도달하여 유사이탈이 더 이상 발생하지 않음을 알 수 있었다. 또한 본 논문에서 수행된 실험결과 자료들을 최종적으로 종합하여 하상토 입경 계수가 포함된 필터층 없는 사석보호공의 무차원 침하량 산정식을 제안하였으며 이러한 연구 결과들은 추후 필터층 없이 시공되는 사석 보호공의 침하 안정성 평가를 위한 지표로 활용될 수 있을 것이다.