• Title/Summary/Keyword: coating properties

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Electrochemical Properties of NiO-YSZ Thin Films on 316 Stainless Steel Bipolar Plates Under a Simulated PEMFC Environment

  • Lee, W.G.;Jang, H.
    • Bulletin of the Korean Chemical Society
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    • v.33 no.4
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    • pp.1177-1182
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    • 2012
  • The corrosion resistance of 316L stainless steel coated with NiO-YSZ (Ni added yttria stabilized zirconia) was examined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carried out using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR) were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increased with increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ film contained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by several orders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare 316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt % NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate.

Evaluation of ultrasonic reflection characteristics on an interface surface using Simulated Annealing (Simulated Annealing기법을 이용한 초음파의 계면 반사 특성평가)

  • 은길수;김노유;나환선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.395-400
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    • 2002
  • Epoxy coating and sealing used in nuclear plants for the protection of radiation degrades with aging and hazardous atmosphere. In order to evaluate the degradation of the epoxy, dependence of the acoustic impedance on the change of mechanical properties has been used. Unlike metals, the surface of the epoxy coating on a concrete liner is so wavy that the acoustic impedance is difficult to measure by using the reflectivity of the ultrasound on the interface surface because of the irregular reflection and propagation from the epoxy surface. SA(simulated annealing) algorithm is applied to calculate the acoustic impedance using a reflection wave from the rough epoxy surface. The surface waviness and acoustic impedance are taken into account and determined by SA method to evaluate the state of degradation quantitatively.

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Computational Flow Analysis of a Large Scale Mixer for Nanopowder Dispersion in Coating Liquid (나노분말이 분산된 기능성 코팅액 제조를 위한 대용량 교반기의 유동해석)

  • Kim, Dongjoo;Kim, Kyoungjin
    • Journal of the Semiconductor & Display Technology
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    • v.12 no.3
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    • pp.1-6
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    • 2013
  • In many technical fields including electronics and display manufacturing processes, properties of coating liquids could be greatly enhanced by adding nanopowders and it requires efficient mixing techniques to achieve uniform dispersion of nanoparticles in liquids. This paper presents the three-dimensional CFD simulations on the flowfields of a highly viscous liquid in the large scale industrial mixer of impeller type. The effects of several important design and operation parameters such as impeller geometry, rotational speed, and degree of liquid viscosity are investigated to appreciate the mixing performance by examining the computational results for flow pattern of rotationally stirred liquid of high viscosity in the mixer.

PEDOT:PSS Thin Films with Different Pattern Structures Prepared Using Colloidal Template

  • Yu, Jung-Hoon;Lee, Jin-Su;Nam, Sang-Hun;Boo, Jin-Hyo
    • Applied Science and Convergence Technology
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    • v.23 no.5
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    • pp.254-260
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    • 2014
  • Organic solar cells have attracted extensive attention as a promising approach for cost-effective photovoltaic devices. However, organic solar cell has disadvantage of low power conversion efficiency in comparison with other type of solar cell, due to the recombination ratio of hole and electron is too large in the active layer. Thus we have change the surface structure of PEDOT:PSS layers to improve the current density by colloidal lithography method using various-size of polystyrene sphere. The two types of coating method were applied to fabricate the different pattern shape and height, such as spin coating and drop casting. Using the organic solvent, we easily eliminate the PS sphere and could make the varied pattern shapes by controlling the wet etching time. Also we have measured the electrical properties of patterned PEDOT:PSS film to check whether it is suitable for organic photovoltaics.

Corrosion Protection Performance of PVDF/PMMA-Blended Coatings by Electrochemical Impedance Method

  • Kim, Yun Hwan;Kwon, Yong Sung;Shon, Min Young;Moon, Myung Jun
    • Journal of Electrochemical Science and Technology
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    • v.9 no.1
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    • pp.1-8
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    • 2018
  • The effect of mixing ratio on the corrosion protection of carbon steel coated by a film composed of poly(vinylidene) fluoride (PVDF) and poly(methyl methacrylate) (PMMA) was examined using electrochemical impedance spectroscopy. Surface crystallization behavior and thermal properties of the PVDF/PMMA coated carbon steel were evaluated using polarized optical microscopy and differential scanning calorimetry, respectively. A Maltese cross-pattern spherulite crystal was observed in the PVDF/PMMA coating film, which became more apparent with increasing PVDF content. The highest corrosion protection performance was achieved with 60 wt.% PVDF-coated carbon steel, and delamination and corrosion reactions were observed for 20 wt.% PVDF-coated carbon steel. Further, corrosion protection performance with an amorphous/crystal mixture (PVDF/PMMA, 60/40 (w/w)) was better than those observed in the amorphous domain and the perfect-crystal domain of the PVDF/PMMA blended coating system.

A Study on Development of Advanced Environmental-Resistant Materials Using Metal Ion Processing

  • Fujita Kazuhisa;Kim Hae-Ji
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1670-1679
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    • 2006
  • The development of the oxidation, wear and corrosion resistant materials that could be used in severe environmental conditions is needed. The elementary technologies for surface modification include ion implantation and/or thin film coating. Furthermore, in order to develop ion implantation technique to the specimens with three-dimensional shapes, plasma-based ion implantation (PBII) techniques were investigated. As a result, it was found that the ion implantation and/or thin film coating used in this study were/was effective for improving the properties of materials, which include implantations of various kinds of ions into TiAl alloy, TiN films formed on surface of base material and coatings in high-temperature steam. The techniques proposed in this study provide useful information for all of the material systems required to use at elevated temperature. For the practical applications, several results will be presented along with laboratory test results.

Alcohol Gas Sensors using Spray-coated Carbon Nanotube Thin Film (스프레이 코팅된 탄소나노튜브 박막을 이용한 알코올 가스 센서)

  • Kim, Seong-Jeen
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.9
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    • pp.783-788
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    • 2008
  • We suggest a CNT-based gas sensor for breath alcohol measurement. The sensor was composed of single-walled carbon nanotubes (SWCNTs) thin film on flexible PES (polyethersulfone) substrate, and the SWCNTs thin film was formed by multiple spray-coating with SWCNTs solution which was well-dispersed, highly controlled and functionalized in ethanol solvent. In this work, three types of SWCNTs thin films were deposited with changes in the number of spray-coatings to 20, 40 and 60 times in order to compare electrical response properties of the SWCNTs thin films. from the fabricated sensors, conductance and capacitance responses were measured and discussed. Alcohol gas sensors have been commercialized widely as gauge for breath alcohol measurement which is applicable to checking whether car drivers are drinking-driving or not. Our alcohol gas sensors showed good sensitivity and linearity even at room temperature.

Characteristics of ATO Thin Films Prepared by Sol-Gel Process (졸겔법으로 제조된 ATO 박막의 특성 연구)

  • 구창영;이동근;이희영
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.192-195
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    • 2000
  • Antimony doped tin oxyde thin films have been deposited by sol-gel method using non-alkoxide precursor SnCl$_2$$.$2H$_2$O as host and SbC1$_3$ as dopant material. Using spin coating method, thin films of thickness up to 200nm have been uniformly deposited on Corning 1737F non-alkali glass substrates. Effect of Sb doping concentration and heat treatment on electrical and optical properties was investigated. Heat treatment was performed at the temperature from 350$^{\circ}C$ to 650$^{\circ}C$ in flowing O$_2$. The resulting ATO films showed widely changing electrical resistivity and optical transmittance values in the visible spectrum depending on the composition and firing condition.

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The Effect of In-flight Bulk Metallic Glass Particle Temperature on Impact Behavior and Crystallization

  • Kim, Soo-Ki;Yoon, Sang-Hoon;Lee, Chang-Hee
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.242-243
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    • 2006
  • NiTiZrSiSn bulk metallic glass powder was produced using inert gas atomization and then was sprayed onto a SS 41 mild steel substrate using the kinetic spraying process. Through this study, the effects of thermal energy of in-flight particle and crystallization degree by powder preheating temperature were evaluated. The deformation behavior of bulk metallic glass is very interesting and it is largely dependent on the temperature. The crystalline phase formation at impact interface was dependent on the in-flight particle temperature. In addition, variations in the impact behavior need to be considered at high strain rate and in-flight particle temperature.

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A comparative study on corrosion behavior of WC-CoCr and WC-CrC-Ni coatings by HVOF

  • Ju, Yun-Gon;Jo, Jae-Yeong;Jang, Si-Hong;Song, Gi-O;Jo, Dong-Yul;Yun, Jae-Hong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2008.11a
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    • pp.155-157
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    • 2008
  • High velocity oxy-fuel (HVOF) thermal spraying coating has been used widely throughout the last 60 years mainly in defense, aerospace, and power plants. Recently this coating technique is considered as a promising candidate for the replacement of the traditional electrolytic hard chrome plating (EHC) which pollutes the environment and causes lung cancer by toxic hexa-valent $Cr^{6+}$. In this study, two kinds of cermet coatings, WC-CoCr and WC-CrC-Ni, are formed by HVOF spraying. The corrosion and electrochemical properties are evaluated by polarization tests in 3.5 wt% solutions.

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