• 제목/요약/키워드: energy-dispersive x-ray spectroscopy (eds)

검색결과 301건 처리시간 0.029초

Use of Stone Powder Sludge in Fly Ash-Based Geopolymer

  • Choi, Se-Jin
    • Architectural research
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    • 제12권1호
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    • pp.49-55
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    • 2010
  • Stone powder sludge is a by-product of the manufacturing process of crushed sand. Most of it is dumped with soil in landfills, and the disposal of stone powder sludge causes a major environmental problem. This paper investigates the applicability of stone powder sludge in fly ashbased geopolymer. For this, stone powder sludge was used to replace fly ash at a replacement ratio of 50% and 100% by weight. The compressive strength of the samples was measured and scanning electron microscopy/ energy dispersive spectroscopy (SEM/EDS) analysis and X-ray diffraction (XRD) were performed. The test results indicated that the optimum level of the alkali activator ratio ($Na_2SiO_3$/NaOH) for fly ash-based geopolymer using stone powder sludge was 1.5. The strength development is closely related to the NaOH solution concentration. In addition, the compressive strength of the sample cured at $25^{\circ}C$ was significantly improved between 7 days and 28 days, even though the strength of the sample showed the lowest value at 7 days. Microscopy results indicated that a higher proportion of unreacted fly ash spheres remained in the sample with 5M NaOH, and some pores on the surface of the sample were observed.

Preparation and characterization of PVDF/TiO2 composite ultrafiltration membranes using mixed solvents

  • Tavakolmoghadam, Maryam;Mohammadi, Toraj;Hemmati, Mahmood
    • Membrane and Water Treatment
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    • 제7권5호
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    • pp.377-401
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    • 2016
  • To study the effect of titanium dioxide ($TiO_2$) nanoparticles on membrane performance and structure and to explore possible improvement of using mixed solvents in the casting solution, composite polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc) and addition of $TiO_2$ nanoparticles. Properties of the neat and composite membranes were characterized using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Atomic force microscopy (AFM) and contact angle and membrane porosity measurements. The neat and composite membranes were further investigated in terms of BSA rejection and flux decline in cross flow filtration experiments. Following hydrophilicity improvement of the PVDF membrane by addition of 0.25 wt.% $TiO_2$, (from $70.53^{\circ}$ to $60.5^{\circ}$) degree of flux decline due to irreversible fouling resistance of the composite membrane reduced significantly and the flux recovery ratio (FRR) of 96.85% was obtained. The results showed that using mixed solvents (DMAc/TEP) with lower content of $TiO_2$ nanoparticles (0.25 wt.%) affected the sedimentation rate of nanoparticles and consequently the distribution of nanoparticles in the casting solution and membrane formation which influenced the properties of the ultimate composite membranes.

Growth of Oriented Thick Films of BaFe12O19 by Reactive Diffusion

  • Fisher, John G.;Vu, Hung;Farooq, Muhammad Umer
    • Journal of Magnetics
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    • 제19권4호
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    • pp.333-339
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    • 2014
  • Single crystal growth of $BaFe_{12}O_{19}$ by the solid state crystal growth method was attempted. Seed crystals of ${\alpha}-Fe_2O_3$ were pressed into pellets of $BaFe_{12}O_{19}$ + 2 wt% $BaCO_3$ and heat-treated at temperatures between $1150^{\circ}C$ and $1250^{\circ}C$ for up to 100 hours. Instead of single crystal growth taking place on the seed crystal, BaO diffused into the seed crystal and reacted with it to form a polycrystalline reaction layer of $BaFe_{12}O_{19}$. The microstructure, chemical composition and structure of the reaction layer were studied using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray Diffraction (XRD) and micro-Raman scattering and confirmed to be that of $BaFe_{12}O_{19}$. XRD showed that the reaction layer shows a strong degree of orientation in the (h00)/(hk0) planes in the sample sintered at $1200^{\circ}C$. $BaFe_{12}O_{19}$ layers with a degree of orientation in the (hk0) planes could also be grown by heat-treating an ${\alpha}-Fe_2O_3$ seed crystal buried in $BaCO_3$ powder.

Characterization of the ultra thin films of silicon oxynitride deposited by plasma-assisted $N_2O$ oxidation for thin film transistors

  • Hwang, Sung-Hyun;Jung, Sung-Wook;Kim, Hyun-Min;Kim, Jun-Sik;Jang, Kyung-Soo;Lee, Jeoung-In;Lee, Kwang-Soo;Jung, Won-June;Dhungel, S.K.;Ghosh, S.N.;Yi, J.
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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    • pp.1462-1464
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    • 2006
  • Scaling rules for TFT application devices have led to the necessity of ultra thin dielectric films and high-k dielectric layers. In this paper, The advantages of high concentration of nitrogen in silicon oxide layer deposited by using $N_2O$ in Inductively Coupled Plasma Chemical Vapor Deposition (ICP-CVD) is investigated using X-ray energy dispersive spectroscopy (EDS). We have reported about Ellipsometric measurement, Capacitance - Voltage characterization and processing conditions.

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Methodological Consideration on the Prediction of Electrochemical Mechanical Polishing Process Parameters by Monitoring of Electrochemical Characteristics of Copper Surface

  • Seo, Yong-Jin
    • Journal of Electrochemical Science and Technology
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    • 제11권4호
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    • pp.346-351
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    • 2020
  • The removal characteristics of copper (Cu) from electrochemical surface by voltage-activated reaction were reviewed to assess the applicability of electrochemical-mechanical polishing (ECMP) process in three types of electrolytes, such as HNO3, KNO3 and NaNO3. Electrochemical surface conditions such as active, passive, transient and trans-passive states were monitored from its current-voltage (I-V) characteristic curves obtained by linear sweep voltammetry (LSV) method. In addition, the oxidation and reduction process of the Cu surface by repetitive input of positive and negative voltages were evaluated from the I-V curve obtained using the cyclic voltammetry (CV) method. Finally, the X-ray diffraction (XRD) patterns and energy dispersive spectroscopy (EDS) analyses were used to observe the structural surface states of a Cu electrode. The electrochemical analyses proposed in this study will help to accurately control the material removal rate (MRR) from the actual ECMP process because they are a good methodology for predicting optimal electrochemical process parameters such as current density, operating voltage, and operating time before performing the ECMP process.

선박용 연료유와 윤활유의 조합에 의한 락커 형성에 관한 연구 (Study on Lacquer Formation in Combined of Marine Fuel Oil and Marine Lubricant Oil)

  • 홍성호;박종국;류영석
    • Tribology and Lubricants
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    • 제31권3호
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    • pp.86-94
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    • 2015
  • We perform lacquer formation experiments with various combinations of marine fuel oils and lubricant oils. We also investigate the influences of base number (BN) in lubricant oil and sulfur content in fuel oil. A dissolution test with 10% dilute sulfuric acid and pull-off force test are accomplished to distinguish whether the residual layers are lacquering or not. The lacquering layers are dissolved by dilute sulfuric acid and have a strong pull-off force. Moreover, the calcium content detected in the residual layers is compared by energy dispersive x-ray spectroscopy (EDS). More calcium is detected in the lacquer layers than in other residual layers. Distillate fuels containing low sulfur levels are more prone to lacquering when mixed with lubricant oil with a high BN. On the other hand, residual fuels with a high sulfur content do not form lacquer. We investigate the effect of mixture volume ratio. The mixture with higher fuel oil content is more prone to generate lacquer. These experiments indicate that a lubricant with an appropriate BN should be used to prevent lacquer forming on the surfaces such as cylinder liners depending on the sulfur content of fuel oil.

CZTS태양전지 흡수층 제작을 위한 열분해법 나노 파티클 합성

  • 이수호;김동욱;이재형
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.444.1-444.1
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    • 2014
  • 높은 광흡수 계수를 갖는 Cu(In,Ga)Se2(CIGS) 화합물 박막 소재는 고효율 태양전지 양산을 위해 가장 전도유망한 재료이나 상대적으로 매장량이 적은 In 및 Ga을 사용한다는 소재적 한계가 있다. Cu2ZnSnSe4(CZTSe) 혹은 Cu2ZnSnS4(CZTS)와 같은 Cu-Zn-Sn-Se계 화합물 반도체는 CIGS 내 희소원소인 In과 Ga이 범용원소인 Zn 및 Sn으로 대체된 소재로써 미래형 저가 태양전지 개발을 위해 활발히 연구되고 있는데, 그 화합물 조합에 따라 0.8eV부터 1.5eV까지의 에너지 밴드갭을 갖는 것으로 알려져 있다. 본 연구에서는 열분해법으로 CZTS 나노 입자를 합성하였다. 용매로 Oleylamine을 사용하였는데, $220^{\circ}C{\sim}340^{\circ}C$의 온도 범위에서 3시간 30분 동안 CZTS 나노입자를 합성하였고, $240^{\circ}C$에서 3시간~5시간까지 합성하였다. 헥산을 이용하여 원심분리기와 초음파세척기로 용매인 Oleylamine을 제거하였고, 진공오븐에서 건조된 CZTS 분말의 FE-SEM(Field Emission Scanning Electron Microscope), XRD(X-Ray Diffraction), EDS(Energy Dispersive Spectroscopy) 분석 등을 통해 합성온도에 따른 구조적, 화학적 조성 변화를 조사하였다.

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Effects of NaF evaporation rate on the properties of $CuInSe_2$ thin-film solar cells

  • 박순용;이은우;이상환;박상욱;정우진;김우남;전찬욱
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2010년도 춘계학술발표대회
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    • pp.36.2-36.2
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    • 2010
  • A small amount of Na incorporated in $CuInSe_2$ (CIS) absorption layer has become widely accepted as a requirement for efficient polycrystalline CIS solar cells. However, there is ongoing argument on the role of sodium incorporated in the absorber. In this paper, CIS absorption layers have been deposited using the three-stage co-evaporation process on Mo coated non-Alkali glass substrates. The NaF was evaporated during the second-stage with various fluxes. This paper is focusing on differences of micro-structure and composition ratio of the absorber realized with different Na contents and the variation of electrical properties of the cells with the corresponding absorbers. The analytical results of x-ray diffraction (XRD) patterns, field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS) and current-voltage characteristics will be discussed to investigate the effect of NaF flux on the CIS absorber formation and its cell performance.

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전기충격법을 통한 몰리브덴이 도핑된 타이타니아 나노튜브 (The preparation of TiO2 nanotubes with a doping of Mo by potential shock)

  • 하동흔;최진섭
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2017년도 춘계학술대회 논문집
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    • pp.145-145
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    • 2017
  • 음극재에 사용되는 타이타니아 나노튜브($TiO_2$ nanotubes)는 높은 종횡비를 가지고 있으며, 기계적인 강도가 우수하고 화학적인 안정성이 높다. 그러나 낮은 전기전도도와 상대적으로 넓은 밴드갭(bandgap)은 다양한 활용 분야에 이 물질이 활용되는 것을 제한하고 있는 상황이다. 전기 화학적 분야에서 광화학 반응 또는 과전압에서 밴드갭을 줄이기 위한 타이타니아 나노튜브의 나노 구조 변형에 대한 많은 연구가 있어왔다. 본 연구에서는 산화 몰리브덴(Molybdenum oxide)을 촉매로 사용하여 타이타니아 나노튜브에 전기충격법을 이용하여 도핑했다. 생성된 타이타니아 나노튜브를 $450^{\circ}C$에서 1시간 30분 동안 가열하여 타이타니아 나노구조를 아나타제(anatase) 구조로 변형켰다. 타이타니아 나노튜브의 구조적인 변화를 scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy(EDS) 등을 통해 측정했고 UV-Visiblespectroscopy를 통해 도핑된 타이타니아 나노튜브의 밴드갭을 측정하였다. 몰리브덴이 도핑된 타이타니아 나노튜브는 기존의 타이타니아 나노튜브가 가지는 밴드갭인 3.0 ~ 3.2eV 범위보다 더 낮아진 2.6 ~ 2.8eV의 범위를 가지는 것을 확인하였다. 몰리브덴이 도핑된 타이타니아 나노튜브는 다양한 광촉매 분야에 적용될 수 있을 것으로 예상된다.

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MSR (Mechanically induced Self-sustaining Reaction)이 억제된 반응성 밀링에 의해 제조된 분산강화 페라이트의 미세조직과 기계적 특성 (Microstructure and Mechanical Properties of ODS Ferrite Produced by Reactive Milling for the MSR Suppression)

  • 황승준
    • 열처리공학회지
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    • 제26권6호
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    • pp.279-287
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    • 2013
  • Oxide Dispersion Strengthened (ODS) Fe with $Al_2O_3$ dispersoid was successfully produced by reactive milling with a mixture of Fe, $Fe_3O_4$ (Magnetite), $Fe_2O_3$ (Hematite) and Al reactants at cryogenic temperature. The milled powders were consolidated by Vacuum Hot Press (HP) at 1323 K, and the consolidated materials were characterized by Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive Spectroscopy (EDS); the yield strength and the hardness of the consolidated materials were determined by compressive test and Vickers hardness test at room temperature. The grain size of the materials was estimated by X-ray Diffraction technique using the scherrer's formula. The TEM observations showed that the microstructure was comprised with a mixture of nanocrystalline Fe matrix and $Al_2O_3$ nano-dispersoids with a bimodal size distribution; the 0.2% off-set yield strength of the materials was as high as $758{\pm}29$ MPa and the Vickers hardness was $358{\pm}2$. The effect of the cryogenic milling and addition of extra Fe powder was discussed on the suppression of MSR (Mechanically induced Self-sustaining Reaction) for the desired microstructural evolution of ODS alloys.