• Title/Summary/Keyword: Dip-coating process

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Preparation and Properties of Y2O3-Doped ZrO2 Films on Etched Al Foil by Sol-Gel Process

  • Chen, Fei;Park, Sang-Shik
    • Korean Journal of Materials Research
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    • v.25 no.2
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    • pp.107-112
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    • 2015
  • The oxide films formed on etched aluminum foils play an important role as dielectric layers in aluminum electrolytic capacitors. $Y_2O_3$-doped $ZrO_2$ (YZ) films were coated on the etched aluminum foils by sol-gel dip coating, and the electrical properties of YZ-coated Al foils were characterized. YZ films annealed at $450^{\circ}C$ were crystallized into a cubic phase, and as the $Y_2O_3$ doping content increased, the unit cell of $ZrO_2$ expanded and the grain size decreased. The etch pits of Al foils were filled by YZ sol when it dried at atmospheric pressure after repeating for several times, but this step could essentially be avoided when being dried in a vacuum. YZ-coated foils indicated that the specific capacitance and dissipation factor were $2-2.5{\mu}F/cm^2$ and 2-4 at 1 kHz, respectively, and the leakage current and withstanding voltage of films approximately 200 nm thick were $5{\times}10^{-4}A$ at 21 V and 22 V, respectively. After being anodized at 500 V, the foils exhibited a specific capacitance and dissipation factor of $0.6-0.7{\mu}F/cm^2$ and 0.1-0.2, respectively, at 1 kHz, while the leakage current and withstanding voltage were $2{\times}10^{-4}-3{\times}10^{-5}A$ at 400 V and 420-450 V, respectively. This suggests that YZ film is a promising dielectric that can be used in high voltage Al electrolytic capacitors.

Preparation of Thin Film Electrolyte for Solid Oxide Fuel Cell by Sol-Gel Method and Its Gas Permeability (졸-겔법을 이용한 고체산화물연료전지의 전해질 박막 제조 및 가스 투과도)

  • Son, Hui-Jeong;Lee, Hye-Jong;Lim, Tak-Hyoung;Song, Rak-Hyun;Peck, Dong-Hyun;Shin, Dong-Ryul;Hyun, Sang-Hoon;Kilner, John
    • Journal of the Korean Ceramic Society
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    • v.42 no.12 s.283
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    • pp.827-832
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    • 2005
  • In this study, thin electrolyte layer was prepared by 8YSZ ($8mol\%$ Yttria-Stabilized Zirconia) slurry dip and sol coating onto the porous anode support in order to reduce ohmic resistance. 8YSZ polymeric sol was prepared from inorganic salt of nitrate and XRF results of xerogel powder exhibited similar results $(99.2\pm1wt\%)$ compared with standard sample (TZ-8YS, Tosoh Co.). The dense and thin YSZ film with $1{\mu}m$ thickness was synthesized by coating of 0.7M YSZ sol followed by heat-treatment at $600^{\circ}C$ for 1 h. Thin film electrolyte sintered at $1400^{\circ}C$ showed no gas leakage at the differential pressure condition of 3 atm.

Effect of Dewpoints on Annealing Behavior and Coating Characteristics in IF High Strength Steels Containing Si and Mn (Si, Mn함유 IF 고강도강의 소둔거동 및 도금특성에 미치는 이슬점 온도의 영향)

  • Jeon, Sun-Ho;Shin, Kwang-Soo;Sohn, Ho-Sang;Kim, Dai-Ryong
    • Korean Journal of Metals and Materials
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    • v.46 no.7
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    • pp.427-436
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    • 2008
  • The effect of dewpoints on annealing behavior and coating characteristics such as wettability and galvannealing kinetics was studied by annealing 0.3wt%Si - 0.1~0.4wt% Mn added interstitial-free high strength steels(IF-HSS). The 0.3wt%Si-0.1wt%Mn steel exhibited good wettability with molten zinc and galvannealing kinetics after annealing when the dewpoint of $H_2-N_2$ mixed gas was above $-20^{\circ}C$. It is shown that the wettability and galvannealing kinetics are directly related to the coverage of the external(surface) oxide formed by selective oxidation during annealing. At $N_2-15%H_2$ annealing atmosphere, the increase of dewpoint results in a gradual transition from external to internal selective oxidation. The decrease of external oxidation of alloying elements with a concurrent increase of their subsurface enrichment in the substrate, showing a larger surface area that was free of oxide particles, contributed to the improved wettability and galvannealing kinetics. On the other hand, the corresponding wettability and galvannealing kinetics were deteriorated with the dewpoints below $-20^{\circ}C$. The continuous oxide layer of network and/or film type was formed on the steel surface, leading to the poor wettability and galvannealing kinetics. It causes a high contact angle between annealed surface and molten zinc and plays an interrupting role in interdiffusion of Zn and Fe during galvannealing process.

Atmospheric Corrosion of Hot Dip Zinc Coated Steel in Coastal and Rural Areas of Vietnam

  • Tru, Nguyen Nhi;Duyen, Le Khac;Han, Tran Mai
    • Corrosion Science and Technology
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    • v.16 no.5
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    • pp.241-246
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    • 2017
  • The comparative results of corrosion testing in humid tropical atmosphere in rural and coastal areas for hot dipped zinc coatings are presented below. The test was conducted in outdoor conditions over a period of five years. The mass loss and other performance characteristics of two types of zinc coatings were evaluated, analysed and discussed in relation to the climatic and environmental parameters. The corrosion rates of the coatings exposed to coastal conditions were about three times higher than the corrosion rates appreciated in rural conditions. The data demonstrates that the corrosion process obeys an equation of the form $M=At^n$, where M is the loss of metal and t is the time of exposure. A and n are constants which values depend on the environmental characteristics and the physicochemical behavior of the corrosion products respectively. Corrosion is strongly influenced by atmospheric time of wetness (TOW) and airborne salinity. The nature and composition of corrosion products are also considered. Simonkolleite, a major crystalline phase, was found in the zinc corrosion products exposed to coastal conditions, while zinc hydroxide and zinc hydrosulfate are easily found in rural settings.

Characteristics of Recycled m-Aramid and TPP Complex Solutions in Preparation and Cotton Fibers after Coating (재활용 메타 아라미드와 TPP 복합용액의 제조 및 면섬유 코팅 후 특성분석)

  • Kim, Sam Soo;Lee, Ji Min;Cho, Ho Hyun;Ryoo, Kyu Yul
    • Textile Coloration and Finishing
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    • v.25 no.4
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    • pp.292-302
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    • 2013
  • Cotton fabrics treated with hybrid materials were developed and prepared. A halogen-free flame retardant and an aromatic amide were blended and applied to cotton fabrics. Thermal and physical properties of the treated cotton fabrics were investigated. The surface of the pure and coated cotton fabrics was characterized by Fourier transform infrared spectroscopy. The elemental composition of the coated surface of the cotton fabric was measured using X-ray photoelectron spectroscopy and compared with that of pure cotton fabric. After being solved in N,N-dimethylacetamide, m-aramid and triphenylphosphine oxide (TPP) were applied to cotton fabrics through a dip-pad-coagulation process. The treated cotton fabrics with recycled m-aramid/TPP resulted in increased limited oxygen index values and thermal resistance.

Synthesis of Aligned ZnO Nanorod Arrays via Hydrothermal Route (수열합성법에 의한 정렬된 ZnO 나노로드 구조의 합성)

  • Koo, Jin Heui;Lee, Byeong Woo
    • Journal of the Korean institute of surface engineering
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    • v.49 no.5
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    • pp.472-476
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    • 2016
  • The nano-array of the vertically aligned rod-like particles grown on ZnO coated glass-substrates was obtained via hydrothermal process. ZnO thin film coatings were prepared on the glass substrates using a MOD (metallorganic deposition) dip-coating method with zinc chloride dihydrate as starting material and 2-ethylhexanol as solvent. ZnO nanorods were synthesized on the seeded substrates by hydrothermal method at $80^{\circ}C$ using zinc-nitrate hexahydrate as a Zn source and sodium hydroxide as a mineralizer. Under the hydrothermal condition, the rod-like nanocrystals were easily attaching on the already ZnO seeded (coated) glass surface. It has been shown that the hydrothermal synthesis parameters are key factors in the nucleation and growth of ZnO crystallites. By controlling of hydrothermal parameters, the ZnO particulate morphology could be easily tailored. Rod-shaped ZnO arrays on the glass substrates consisted of elongated crystals having 6-fold symmetry were predominantly developed at high Zn precursor concentration in the pH range 7~11.

Synthesis of highly crystalline nanoporous titanium dioxide at room temperature (상온에서 고결정성 나노기공 이산화티탄 제조기술)

  • Chung, Pyung Jin;Kwon, Yong Seok
    • Journal of Energy Engineering
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    • v.25 no.2
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    • pp.65-78
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    • 2016
  • Initial studies of the photocatalyst has been developed from the field relating to the conversion and storage of solar energy. Recently, the study of the various organic decomposition compound and the water purification and waste water treatment by ultraviolet irradiation in the presence of light or a photocatalyst are being actively investigated. In addition, the oxidized material-carbon nanotubes, graphene-nanocomposites have been studied. Such a complex is suitable as a material constituting the solar cells and photolysis nanoelectronics, including the flexible element due to thermal and chemical stability.

Electrochemical Study on PVDF-HFP/Silylated Al2O3-coated PE Separators using the Electron Beam Irradiation for Lithium Secondary Battery (전자선을 이용한 PVDF-HFP/Silylated Al2O3가 코팅된 리튬 이차 전지용 폴리에틸렌 분리막의 전기화학적 특성 연구)

  • Sohn, Joon-Yong;Shin, Junhwa;Nho, Young-Chang
    • Journal of Radiation Industry
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    • v.4 no.4
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    • pp.359-364
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    • 2010
  • PVDF-HFP (binder)/silylated alumina (inorganic particle)-coated PE (polyethylene) separators were with various compositions of binder and inorganic particle were prepared by a dip-coating process with humidity control (R.H. 25% and 50%) using electron beam irradiation. The morphology of the coated PVDF-$HFP/Al_2O_3$ layer with various compositions of PVDF-HFP and $Al_2O_3$, and humidity condition was found to be an important factor in determining ionic conductivity of the prepared separators. The PVDF-$HFP/Al_2O_3$ (5/5)-coated PE separator prepared at R.H. 50% followed by electron beam irradiation at 200 kGy was applied for lithium-ion polymer battery and the cell test results showed improved high-rate discharge performance and better cyclic stability compared to the cells with the bare PE and the PVDF-HFP-coated PE separators.

MOD-processed YBCO coated conductors on the $CeO_2$-buffered IBAD-MgO template

  • Shin, G.M.;Ko, R.K.;Oh, S.S.;Moon, S.H.;Yoo, S.I.
    • Progress in Superconductivity and Cryogenics
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    • v.11 no.4
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    • pp.20-24
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    • 2009
  • YBCO coated conductors (CC) on the $CeO_2$-buffered IBAD-MgO template were fabricated by metal-organic deposition (MOD) Process with Ba-trifluoroacetate and fluorine-free Y and Cu precursor materials. The precursor solution was coated on $CeO_2$-buffered IBAD MgO templates using the multiple dip-coating method, decomposed into inorganic precursors by pyrolysis up to $400^{\circ}C$ within 3 h, and finally fired at $740{\sim}800^{\circ}C$ in a reduced oxygen atmosphere. Microstructure, texture, and superconducting properties of YBCO films were found highly sensitive to both the firing temperature and time. The high critical current density ($J_C$) of $1.15\;MA/cm^2$ at 77.3K in the self-field could be obtained from $1\;{\mu}m$ thick YBCO CC, fired at $740^{\circ}C$ for 3.5 h, implying that high performance YBCO CC is producible on IBAD MgO template. Further enhancement of $J_C$ values is expected by improving the in-plane texture of $CeO_2$-buffer layer and avoiding the metal substrate contamination.

Solution deposition planarization for IBAD-MgO texture template

  • Ko, Kyeong-Eun;Kwon, O-Jong;Bea, Sung-Hwan;Yoo, Ja-Eun;Park, Chan;Oh, Sang-Soo;Park, Young-Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.12 no.4
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    • pp.17-19
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    • 2010
  • In this work, the optimized process condition of chemical solution deposition which is used to planarize the surface of the metal tape (which is used to grow IBAD-MgO texture template) was investigated. $Y_2O_3$ films were dip-coated on the surface of the unpolished metal tape as the seed and barrier layer. The effects of $Y_2O_3$ concentration of the solution (0.5wt.%, 1.3wt.%, 2.8wt.%, 5.6wt.%) and the number of coatings on the surface morphology and barrier capability against the diffusion from the metal tape were examined. The surface morphology and the thickness of the film were observed using the scanning electron microscope and the atomic force microscope. The presence of elements in metal tape on the film surface was analyzed using the auger electron spectroscopy. The $Y_2O_3$ film thickness increases with increasing the $Y_2O_3$ concentration in the solution, and the surface became smoother with increasing the number of coating cycles. The best result was obtained from the $Y_2O_3$ film coated 4 cycles using 2.8wt.% solution.