• 제목/요약/키워드: surface-coated

검색결과 3,102건 처리시간 0.038초

High-temperature oxidation behaviors of ZrSi2 and its coating on the surface of Zircaloy-4 tube by laser 3D printing

  • Kim, Jae Joon;Kim, Hyun Gil;Ryu, Ho Jin
    • Nuclear Engineering and Technology
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    • 제52권9호
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    • pp.2054-2063
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    • 2020
  • The high-temperature oxidation behavior of ZrSi2 used as a coating material for nuclear fuel cladding was investigated for developing accident-tolerant fuel cladding of light water reactors. Bulk ZrSi2 samples were prepared by spark plasma sintering. In situ X-ray diffraction was conducted in air at 900, 1000, and 1100 ℃ for 20 h. The microstructures of the samples before and after oxidation were examined by scanning electron microscopy and transmission electron microscopy. The results showed that the oxide layer of zirconium silicide exhibited a layer-by-layer structure of crystalline ZrO2 and amorphous SiO2, and the high-temperature oxidation resistance was superior to that of Zircaloy-4 owing to the SiO2 layer formed. ZrSi2 was coated on the Zircaloy-4 tube surface using laser 3D printing, and the coated tube was oxidized for 2000 s at 1200 ℃ under a vapor/argon mixture atmosphere. The outer surface of the coated tube was hardly oxidized (10-30 ㎛), while the inner surface of the uncoated tube was significantly oxidized to approximately 300 ㎛.

탄소분말이 물리적으로 코팅된 리튬 음전극의 충방전 특성 (Charge-Discharge Characteristics of Physically Coated Lithium Anodes by Carbon Powders)

  • 김광만;이상효;이영기
    • Korean Chemical Engineering Research
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    • 제49권5호
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    • pp.554-559
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    • 2011
  • 리튬금속을 음전극으로 사용할 때의 안전성과 전극 특성을 개선하기 위해, 리튬금속 표면에 각기 종류가 다른 3가지의 탄소분말을 리튬금속 표면에 물리적으로 코팅한 전극을 제조하고 이를 리튬 2차전지의 음전극으로 채택하여 충방전 특성을 조사하였다. 일차입자의 입경이 작고 비표면적이 큰 탄소분말로 코팅한 음전극을 채택하는 경우가 충진밀도가 높고 표면 거칠기가 낮으며, 충방전 특성도 우수하게 나타났다. 이러한 탄소분말 코팅 효과는 소형 셀일수록 더욱 유리하게 나타났다.

마이크로다공성 코팅된 인접 복수 발열체에 대한 PF5060의 냉각 특성 (Characteristics of Cooling for the Adjacent Double Micro-Porous Coated Surfaces in PE5060)

  • 김태균;김윤호;이규정
    • 대한기계학회논문집B
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    • 제30권7호
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    • pp.646-655
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    • 2006
  • The present research is an experimental study on characteristics of cooling behavior for the adjacent copper blocks with surface roughness or micro-porous coated surface. The experiments were carried out at saturation state or within subcooled states of PF5060. The effects of heater orientation and the intervals between heating surfaces or substrates were investigated under various heat flux conditions. The boiling performance of copper block with micro-porous coated surface was better than that of copper block with surface roughness. It is understood that the bubble sweeping enhances boiling performance for the heaters with inclinations of $\theta=45^{\circ}\;and\;\theta=90^{\circ}$, where as the bubble flattening decreases boiling performance for the heaters with inclinations of $\theta=135^{\circ}\;and\;\theta=180^{\circ}$. In comparison to upper heater and below heater with orientation, the upper heater has lower superheat temperature than the below heater due to the bubble sweeping. It is also found that boiling performance decreases in the case of adjacent double heaters with only 0.2cm substrate interval.

와이어전극의 도금재료가 W-EDM 가공성에 미치는 영향 (The Coating Materials of Electrode Materials on Machinability of W-EDM)

  • 김창호;허관도
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2000년도 춘계학술대회 논문집
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    • pp.735-738
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    • 2000
  • The characteristics of wire electrical discharge machining (WEDM) are governed by many factors such as the power supply type, operating condition and electrode material. This work deals with the effect of wire electrode materials on the machining characteristics such as, metal removal rate, surface characteristics and surface roughness during WEDM A wire's thermal physical properties are melting point, electrical conductivity and vapor pressure. One of the desired qualities of wire is a low melting point and high vapor pressure to help expel the contaminants from the gap. They are determined by the mix of alloying elements (in the case of plain brass and coated wire) or the base core material(i.e. molybdenum). Experiments have been conducted regarding the choice of suitable wire electrode materials and influence of the properties of these materials on the machinability and surface characteristics in WEDM, the experimental results are presented and discussed from their metallurgical aspect. And the coating effect of various alloying elements(Au, Ag, Cu, Zn, Cr, Mn, etc.) to the Cu or 65-35 brass core on them was reviewed also. The removal rate of some coated wires are higher than that of 65-35 brass electrode wire because the wire is difficult to break due to the wire cooling effect of Zn evaporation latent heat and the Zn oxide on the surface is effective in preventing short circuit. The removal rate increases with increasing Zn content from 35, 40 and Zn coated wire

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A Composite of Metal and Polymer Films: Thin Nickel Film Coated on a Polypropylene Film after Atmospheric Plasma Induced Surface Modification

  • Song, Ho-Shik;Choi, Jin-Moon;Kim, Tae-Wan
    • Transactions on Electrical and Electronic Materials
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    • 제12권3호
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    • pp.110-114
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    • 2011
  • Polymeric films of high chemical stability and mechanical strength covered with a thin metallic film have been extensively used in various fields as electric and electronic materials. In this study, we have chosen polypropylene (PP) as the polymer due to its outstanding chemical resistance and good creep resistance. We coated thin nickel film on PP films by the electroless plating process. The surfaces of PP films were pre-treated and modified to increase the adhesion strength of metal layer on PP films, prior to the plating process, by an environment-friendly process with atmospheric plasma generated using dielectric barrier discharges in air. The surface morphologies of the PP films were observed before and after the surface modification process using a scanning electron microscope (SEM). The static contact angles were measured with deionized water droplets. The cross-sectional images of the PP films coated with thin metal film were taken with SEM to see the combined state between metallic and PP films. The adhesion strength of the metallic thin films on the PP films was confirmed by the thermal shock test and the cross-cutting and peel test. In conclusion, we made a composite material of metallic and polymeric films of high adhesion strength.

염료감응형 태양전지에서 $TiO_2$ 반도체전극 표면의 다양한 overlayer 코팅에 따른 특성연구 (A Study of Surface Modification of TiO2 Semiconductor Electrode by Various Overlayers Coating in Dye Sensitized Solar Cells(DSSC))

  • 김준탁;김상호
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2009년도 춘계학술대회 논문집
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    • pp.100-100
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    • 2009
  • $TiO_2$ is widely being used as a semiconductor electrode for DSSC. Anti-recombination property and surface area of $TiO_2$ give an important influence to the DSSC efficiency. In this study, $TiO_2$ electrode was fabricated on FTO using screen printing method. Various overlayers were coated on them by dip coating in solution of saturated $Ba(NO_3)_2$, $Mg(NO_3)_2$ and $N_{2}O_{6}Sr$. They reduced the recombination of electrons from photo excited state of Ru dye. The atmospheric plasma treatment was applied to both the $TiO_2$ and each overlayer coated $TiO_2$ surfaces to improve contact ability with dye. We prepared four samples, one sample has bare $TiO_2$ surfaces to improve contact ability with dye. We prepared four samples, one sample has bare $TiO_2$ electrode and the other samples consist of each overlayer coated $TiO_2$ electrodes. We used XRD, FE-SEM, J-V, IPCE and EIS in order to investigate characteristic.

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