• Title/Summary/Keyword: composite coating

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Recent Advances in Metal Organic Framework based Thin Film Nanocomposite Membrane for Nanofiltration (나노여과를 위한 금속유기구조체 기반 박막 나노복합막의 최근 발전)

  • Kim, Esther;Patel, Rajkumar
    • Membrane Journal
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    • v.31 no.1
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    • pp.35-51
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    • 2021
  • Advancements in thin-film nanocomposite (TFN) membrane technology for nanofiltration is crucial for removing pollutants from natural resources. In recent years, various metal-organic framework (MOF) modifications have been tested to overcome the drawbacks that are inevitable with conventional thin-film composite (TFC) and TFN membranes. In general, MIL-101(Cr), UiO-66, ZIF-8, and HKUST-1 [Cu3(BCT2)] are MOFs that were proven to exhibit excellent membrane performance in terms of solvent permeability and solute rejection; their respective studies are reviewed in this article. Other novelties, such as the simultaneous use of different MOFs and unique MOF layering techniques (e.g., dip-coating, spray pre-disposition, Langmuir-Schaefer film, etc.) are also discussed as they present alternate solutions for membrane enhancement and/or preparation convenience. Not only are these MOF-modified TFN membranes frequently shown to improve separation performance from their respective TFC and TFN membranes, but many reports also explain their potential for a cost-effective and environmentally friendly process. In this review the thin film nanocomposite nanofiltration membrane is discussed.

Electrochemical Characteristics of Dopamine coated Silicon/Silicon Carbide Anode Composite for Li-Ion Battery (리튬이온배터리용 도파민이 코팅된 실리콘/실리콘 카바이드 음극복합소재의 전기화학적 특성)

  • Eun Bi Kim;Jong Dae Lee
    • Korean Chemical Engineering Research
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    • v.61 no.1
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    • pp.32-38
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    • 2023
  • In this study, the electrochemical properties of dopamine coated silicon/silicon carbide/carbon(Si/SiC/C) composite materials were investigated to improve cycle stability and rate performance of silicon-based anode active material for lithium-ion batteries. After synthesizing CTAB/SiO2 using the Stöber method, the Si/SiC composites were prepared through the magnesium thermal reduction method with NaCl as heat absorbent. Then, carbon coated Si/SiC anode materials were synthesized through polymerization of dopamine. The physical properties of the prepared Si/SiC/C anode materials were analyzed by SEM, TEM, XRD and BET. Also the electrochemical performance were investigated by cycle stability, rate performance, cyclic voltammetry and EIS test of lithium-ion batteries in 1 M LiPF6 (EC: DEC = 1:1 vol%) electrolyte. The prepared 1-Si/SiC showed a discharge capacity of 633 mAh/g and 1-Si/SiC/C had a discharge capacity of 877 mAh/g at 0.1 C after 100 cycles. Therefore, it was confirmed that cycle stability was improved through dopamine coating. In addition, the anode materials were obtain a high capacity of 576 mAh/g at 5 C and a capacity recovery of 99.9% at 0.1 C/0.1 C.

Impregnation Behavior of SiCf/SiC Composites Depending on the Polycarbosilane Precursor and Solvent (폴리카보실란의 종류와 용제에 따른 SiCf/SiC복합재의 충진 거동)

  • Kim, Sun-Han;Jung, Yang-Il;Park, Jeong-Yong;Kim, Hyun-Gil;Koo, Yang-Hyun;Hong, Sun-Ig
    • Korean Journal of Materials Research
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    • v.24 no.9
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    • pp.474-480
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    • 2014
  • Process conditions for the impregnation of polycarbosilane preceramic polymer into SiC-based composites were investigated. Two kinds of preceramic polymer (PCP) was impregnated into SiC-fiber fabrics with different solvents of n-hexane and divinylbenzene (DVB). Both microstructural observations and mechanical tests were conducted to evaluate the impregnation. The matrix phases were particulated in the case of hexane solvents. Apparent relative density of the matrix was about 78.8%. The density of matrix was increased to about 96.1-98.8% when the DVB was used; however, brittle fracture was observed during a bending test. The modulus of toughness was less than $0.74J/m^3$. The fabric impregnated with a mixed PCP-dissolved solution showed intermediate characteristics with relative high density of filling (apparent density of ~96.1%) as well as proper bending behavior. The modulus of toughness was increased to about $5.31J/m^3$. The composites developed by changing the precursor and solvent suggested the possibility of fabricating SiCf/SiC composites without a fiber to matrix interphase coating.

BaTiO3 Particles of Core-Shell Structure for Aqueous Paste to Avoid VOC Emission during MLCC Manufacturing Process (MLCC 제조공정에서 VOC배출 억제를 위한 수계 Paste용 BaTiO3 코팅분말의 합성)

  • Kim, Jin-Su;Choi, Guang J.
    • Clean Technology
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    • v.8 no.4
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    • pp.173-180
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    • 2002
  • As a primary material for MLCC, $BaTiO_3$ particles coated with two additives in a core-shell structure were prepared in this study. This composite powder can not only reduce the VOC emission during MLCC manufacture but also increase the density and reliability of electronic products. The additives were $Y_2O_3$ and $MnCO_3$, whose composition information was obtained from domestic companies. It was observed that the surface of $BaTiO_3$ particles was uniformly as well as simultaneously coated by those two materials via urea-decomposition reaction over $70^{\circ}C$ as the reaction temperature. Elemental analysis indicated that the measured content of each additve was quite close to the designated value. The effect of polymeric dispersant such as PVP, on the coating characteristics was not as significant as expected.

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The effect of tooth brushing and thermal cycling on a luster change of ceromers finished with different methods

  • Cho, Lee-Ra;Yi, Yang-Jin
    • The Journal of Korean Academy of Prosthodontics
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    • v.38 no.3
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    • pp.336-347
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    • 2000
  • Statement of problem. Luster loss in esthetic anterior ceromer restoration can occur and can be related with rough surface texture. Understanding durability of surface finishing methods like polishing and surface coating have critical importance. Purpose. This study evaluated the effect of tooth brushing and thermal cycling on surface luster of 3 ceromer systems (Artglass, Targis, Sculpture) treated with different surface finishing methods. Material and methods. Seventy-two samples were prepared: 12 for control group Z100, 12 for Artglass, 24 for Targis, and 24 for Sculpture. Half of the Targis and Sculpture were polished according to the manufacturer's recommendation. The rest of the samples were coated with staining and glazing solution for Targis and Sculpture, respectively. All specimens were subjected to 10,000 cycles between $5^{\circ}C\;and\;55^{\circ}C$ with 30 seconds dwell time. Tooth brushing abrasion tests were performed in a customized tooth brushing machine with 500g back and forth for 20,000 cycle. Luster comparisons were based on grading after direct observation, and light reflection area was measured with Image analysis software. Results. All materials showed an decrease in luster grade after thermal cycling and tooth brushing. The post-tooth brushing results revealed that the glazed Sculpture had greater mean luster grade than did any other groups. While, the stained Targis group showed greatest changes after tooth brushing (p < 0.05), polished Targis and Sculpture did not show significant changes. However, glazed Sculpture showed discretely fallen out glaze resin. Conclusion. From the results of this study, all of the ceromer specimens were much glossy than control composite group after tooth brushing. coatings used for Targis and Sculpture had not durability for long term use.

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Fabrication and Electrochemical Characterization of LSM/GDC based Cathode Supported Direct Carbon Fuel Cells (직접탄소 연료전지용 LSM/GDC 공기극 지지체 제조 및 전기화학 특성 평가)

  • Ahmed, Bilal;Wahyudi, Wandi;Lee, Seung-Bok;Song, Rak-Hyun;Lee, Jong-Won;Lim, Tak-Hyoung;Park, Seok-Joo
    • Journal of Hydrogen and New Energy
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    • v.24 no.3
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    • pp.230-236
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    • 2013
  • In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at $1400^{\circ}C$. The porous structure of LSM/GDC cathode substrate, after sintering at $1400^{\circ}C$, was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V, independent of testing temperature. The peak power densities were 116, 195 and $225mWcm^{-2}$ at 750, 800 and $850^{\circ}C$, respectively.

A Study on Development of Electro Magnetic Wave Absorbers for Mobile Phones (휴대전화 단말기용 전파 흡수체의 개발에 관한 연구)

  • Choi Yun-Seok;Jung Jae-Hyun;Kim Dong-Il
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.5 s.108
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    • pp.423-429
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    • 2006
  • This paper deals with research for development of electromagnetic wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, and the milling time, electromagnetic wave absorbers were prepared and examined. Central frequency shills toward lower 2.2 GHz, 1.29 GHz, 842 MHz with increasing thickness 1 mm, 2 mm, 3 mm of the absorber, and absorption ability controlled each 2.2 GHz to 1.91 GHz, 1.29 GHz to 801 MHz, 842 MH2 to 801 MHz adjust sendust amount from 80 wt% to 85 wt%. The absorption band of the electromagnetic wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated electromagnetic wave absorbers show a reflection coefficient 5.76 dB at 1.8 GHz in thickness of 0.85 mm.

Effect of reaction factors on the characteristics of Ni-coating layer onto graphite (흑연표면의 니켈코팅층 특성에 미치는 반응인자의 영향)

  • Dong Jin Kim;Hun Saeong Chung;Myung Kyu Jung;Ki Byoung Youn
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.4
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    • pp.395-404
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    • 1994
  • Ni-graphite composite powders were prepared by reduction of $Ni^{++}$ from ammoniacal nickel sulfate solution on graphite core by hydrogen gas. Effect of reaction factors on the reduction rate and the properties of nickel layer were investigated by SEM, Optical Microscopy, size and chemical analysis. Induction period, a time lag between the injection of hydrogen gas and the start of the reduction, was 20~110 mins and affected by the reaction temperature and stirring speed. The reduction rate of $Ni^{++}$ was $4.5g/{\ell}/min$ at optimum condition and increased with increasing reaction temperature and stirring speed.

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Application of Nano Coating to ACSR conductor for the Protection of Transmission lines against Solar Storms, Surface Flashovers, Corona and Over voltages

  • Selvaraj, D. Edison;Mohanadasse, K.;Sugumaran, C. Pugazhendhi;Vijayaraj, R.
    • Journal of Electrical Engineering and Technology
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    • v.10 no.5
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    • pp.2070-2076
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    • 2015
  • Nano composite materials were multi-constituent combinations of nano dimensional phases with distinct differences in structure, chemistry and properties. Nano particles were less likely to create large stress concentrations and thereby can avoid the compromise of the material ductility while improve other mechanical properties. Corona discharge was an electrical discharge. The ionization of a fluid surrounding a conductor was electrically energized. This discharge would occur when the strength of the electric field around the conductor was high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects. This paper shows all the studies done on the preparation of nano fillers. Special attention has given to the ACSR transmission line conductor, TiO2 nano fillers and also to the evaluation of corona resistance on dielectric materials discussed in detail. The measurement of the dielectric properties of the nano fillers and the parameters influencing them were also discussed in the paper. Corona discharge test reveals that in 0%N ACSR sample corona loss was directly proportional to the applied line voltage. No significant change in corona loss between 0%N and 1%N. When TiO2 nano filler concentration was increased up to 10%N fine decrement in corona loss was found when compared to base ACSR conductor, corona loss was decreased by 40.67% in 10%N ACSR sample. It was also found from the surface conditions test that inorganic TiO2 nano filler increases the key parameters like tensile strength and erosion depth.

THE EFFECT OF TEMPORARY FILLING MATERIALS ON THE ADHESION BETWEEN DENTIN ADHESIVE-COATED SURFACE AND RESIN INLAY (레진코팅된 상아질 표면과 레진인레이간 결합에 임시가봉재가 미치는 영향)

  • Kim, Tae-Gun;Lee, Kwang-Won;Yu, Mi-Kyung
    • Restorative Dentistry and Endodontics
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    • v.33 no.6
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    • pp.553-559
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    • 2008
  • The purpose of this research was to compare the microtensile bond strength of resin coated surface and resin inlay according temporary filling materials prior to applying self-adhesive resin cement. Caviton(GC, Japan), Provifil(Promedica, Neumunster, Germany), Provifil(Promedica, Neumunster, Germany) & petrolatum, and Eugenol-based cement, Tembond(Kerr, Orange CA, USA) were used as temporary filling materials. After fabrication of Tescera(Bisco, Schamburg IL, USA), it was bonded with a self-adhesive resin cement, Rely X unicem(3M, St. Paul. Minn, USA). After this procedure, the microtensile bond strength was measured and it was analyzed through one-way ANOVA and Duncan test(p<0.05). Caviton(GC, Tokyo, Japan) showed statistical difference except for the control(group I) and the saliva(group II)(p<0.05). Provifil(group IV), Provifil & petroneum(group V), Tembond(group VI) had lower microtensile bond strength.