• Title/Summary/Keyword: cobalt coating

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Corrosion Protection Properties of Cobalt Salt for Water-Based Epoxy Coatings on 2024-T3 Aluminum Alloy

  • Thai, Thu Thuy;Trinh, Anh Truc;Pham, Gia Vu;Pham, Thi Thanh Tam;Xuan, Hoan Nguyen
    • Corrosion Science and Technology
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    • v.19 no.1
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    • pp.8-15
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    • 2020
  • In this paper, the efficiency and the inhibition mechanisms of cobalt salts (cobalt nitrate and cobalt-exchange silica Co/Si) for the corrosion protection of AA2024 were investigated in a neutral aqueous solution by using the electrochemical impedance spectroscopy (EIS) and polarization curves. The experimental measurements suggest that cobalt cation plays a role as a cathodic inhibitor. The efficiency of cobalt cation was important at the concentration range from 0.001 to 0.01 M. The formation of precipitates of oxides/hydroxides of cobalt on the surface at low inhibitor concentration was confirmed by the Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) analysis. EIS measurements were also conducted for the AA2024 surface covered by water-based epoxy coating comprising Co/Si salt. The results obtained from exposure in the electrolyte demonstrated the improvement of the barrier and inhibition properties of the coating exposed in the electrolyte solution for a lengthy time. The SEM/EDS analysis in artificial scribes of the coating after salt spray testing revealed the release of cobalt cations in the coating defect to induce the barrier layer on the exposed AA2024 substrate.

Thermal Degradation of Black Cobalt Solar Selective Coatings (흑색 코발트 태양 선택흡수막의 열퇴화)

  • Lee, Kil-Dong
    • Journal of the Korean Solar Energy Society
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    • v.35 no.4
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    • pp.9-15
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    • 2015
  • Black cobalt solar selective coatings were prepared by using an electroplating method. The changes in the optical properties of the black cobalt selective coating due to thermal degradation were analyzed by using the Auger electron spectroscopy (AES) and spectrophotometer. The black cobalt selective coating was prepared on a copper substrate by using a synthesized electrolyte with $CoCl_2$ and KSCN at a current density of ${\sim}0.5A/dm^2$ for 45s ~ 60s. Its optical properties were a solar absorptance (${\alpha}$) of the order of 0.80 ~ 0.84 and a thermal emittance (${\epsilon}$) of 0.01. From the AES depth profile analysis of heated sample, thermal degradation of the black cobalt selective coating heated for 33 hours at temperature of $350^{\circ}C$ occurred primarily due to interdiffusion at interface of cobalt and copper substrate. This results were predictable that the ${\alpha}$ decreases due to the thermal oxidation and diffusion.

Coating of Cobalt Over Tungsten Carbide Powder by Wet Chemical Reduction Method

  • Hong, Hyun-Seon;Yoon, Jin-Ho
    • Journal of Powder Materials
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    • v.21 no.2
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    • pp.93-96
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    • 2014
  • Cobalt coated tungsten carbide-cobalt composite powder has been prepared through wet chemical reduction method. The cobalt sulfate solution was converted to the cobalt chloride then the cobalt hydroxide. The tungsten carbide powders were added in to the cobalt hydroxide, the cobalt hydroxide was reduced and coated over tungsten carbide powder using hypo-phosphorous acid. Both the cobalt and the tungsten carbide phase peaks were evident in the tungsten carbide-cobalt composite powder by X-ray diffraction. The average particle size measured via scanning electron microscope, particle size analysis was around 380 nm and the thickness of coated cobalt was determined to be 30~40 nm by transmission electron microscopy.

Reactions of Various Ceramic Materials with Cobalt Sulfate Solution (황산코발트 용액에 의한 다양한 세라믹소지의 반응)

  • Won, Il-An;Kim, Kyung-Nam
    • Korean Journal of Materials Research
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    • v.24 no.2
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    • pp.93-97
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    • 2014
  • In this study, a cobalt sulfate ceramic coating was sintered on various clays at $1250^{\circ}C$. The specimen characteristics were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), TG-DTA, UV-vis spectrophotometer, and HRDPM. The ceramic coating had a constant thickness of thousands ${\mu}m$, and the surface was confirmed to be densely fused. Other new compounds were produced by the cobalt sulfate sintering process and reactions. These compounds were a $CoAl_2O_4$ phase, $Co_2SiO_4$ phase, anorthite($CaAl_2Si_2O_8$) phase, and $FeAl_2O_4$ phase, respectively. UV properties of the coated specimen were investigated, celadon clay specimen in 530-550 nm band is showing a dark gray color. The white clay and white mix clay specimen in 460-500 nm band is showing a blue color. The cobalt-aluminate($CoAl_2O_4$) spinel and the cobalt-silicate olivine($Co_2SiO_4$) were the strongest of the ceramic pigments, producing a very pure, navy blue color.

Optical Properties and Structure of Black Cobalt Solar Selective Coatings (흑색 코발트 태양 선택흡수막의 광학적특성과 구조)

  • Lee, Kil-Don
    • Journal of the Korean Solar Energy Society
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    • v.31 no.4
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    • pp.48-56
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    • 2011
  • Black cobalt solar selective coatings were prepared by thermal oxidation of electroplated cobalt metal on copper and nickel substrates. The optical properties and structure of the black cobalt selective coating for solar energy utilizations were characterized by glow discharge spectrometry (GDS), ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer, atom force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). The optical properties of optimum black cobalt selective coating prepared on copper substrate were a solar absorptance of 0.82 and a thermal emittance of 0.01. From the GDS depth profile analysis of these coatings, the concentration of cobalt particles near the interface was higher than at the surface, but oxygen concentration at the surface was higher than at the interface. These results suggest that the selective absorption was dominated by this chemical composition variation in the coating. The surface of this film exhibited morphology with root-mean-square(rms) roughness of about 144.3nm. XPS measurements data showed that several phases of Co coexist($Co_3O_4$,CoO) in the film.

Effects of Cobalt Protective Coating Prepared by DC Electroplating on Ferritic Stainless Steel for SOFC Interconnect (직류 전기도금을 이용한 고체산화물 연료전지 금속연결재용 페라이트계 스테인리스 스틸의 코발트 보호막 코팅 효과)

  • Hong, Jong-Eun;Lim, Tak-Hyung;Song, Rak-Hyun;Lee, Seung-Bok;Shin, Dong-Ryul;Yoo, Young-Sung;Lee, Dok-Yol
    • Journal of Hydrogen and New Energy
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    • v.20 no.2
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    • pp.116-124
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    • 2009
  • We investigated the influences of cobalt coating deposited by DC electroplating on the ferritic stainless steel, STS 430, as a protective layer on a metallic interconnect for SOFC applications. Cobalt coated STS 430 revealed a uniform and denser-packing oxide surface and a reduced growth rate of $Cr_2O_3$ scales after oxidation at $800^{\circ}C$in air. Cobalt coating layer was oxidized to $CoCo_2O_4$ and Co containing mixed oxide spinels such as $Co_2CrO_4$, $CoCr_2O_4$, and $CoCrFeO_4$. The area specific resistance value of Co coated sample was $0.020\;{\Omega}cm^2$ lower than that of uncoated at $800^{\circ}C$ in air during 500 h. After 1000 h oxidation, cobalt oxide coating layer suppressed chromium outward diffusion.

Characterization of Ceramic Material Coating by Cobalt Sulfate Using Spray Technique

  • Kim, Myung-Je;Won, Il-An;Kim, Kyung-Nam
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2013.05a
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    • pp.180-180
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    • 2013
  • Ceramic glaze has been developed by numerous experiences and knowhow of potters for a long time. It has offered curiosity and beauty to many people with a variety of colors. This study first verifies the color difference according to clays and glazing used for the coloration experiment based on generation process and chemical reaction of cobalt sulfate, and determines the effect of a dilution ratio with water on changes in coloration concentration. The cobalt-aluminate spinel and the cobalt-silicate olivine are the strongest of the ceramic pigment, producing a very pure, navy blue color.

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Corrosion Protection Properties of Co3O4 and CoFe2O4 Nanoparticles for Water-Based Epoxy Coatings on 2024-T3 Aluminum Alloys

  • Thu Thuy Thai;Anh Truc Trinh;Thi Thanh Tam Pham;Hoan Nguyen Xuan
    • Corrosion Science and Technology
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    • v.22 no.2
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    • pp.90-98
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    • 2023
  • In this study, cobalt oxide (Co3O4) and cobalt-doped magnetite (CoFe2O4) nanoparticles were synthesized by a hydrothermal method. They were then used as corrosion inhibitors for corrosion protection of AA2024-T3 aluminum alloys. These obtained nanoparticles were characterized by x-ray diffraction, field-emission scanning electron microscopy, and Zeta potential measurements. Corrosion inhibition activities of Co3O4 and CoFe2O4 nanoparticles were determined by performing electrochemical measurements for bare AA2024-T3 aluminum alloys in 0.05 M NaCl + 0.1 M Na2SO4 solution containing Co3O4 or CoFe2O4 nanoparticles. Corrosion protection for AA2024-T3 aluminum alloys by a water-based epoxy with or without the synthesized Co3O4 or CoFe2O4 nanoparticles was investigated by electrochemical impedance spectroscopy during immersion in 0.1 M NaCl solution. The corrosion protection of epoxy coating deposited on the AA2024-T3 surface was improved by incorporating Co3O4 or CoFe2O4 nanoparticles in the coating. The corrosion protection performance of the epoxy coating containing CoFe2O4 was higher than that of the epoxy coating containing Co3O4.

Silica Coating of Nanosized CoFe2O4 Particles by Micro-emulsion Method (마이크로에멀젼법을 이용한 나노 CoFe2O4 분말의 실리카 코팅)

  • Kim, Yoo-Jin;Yu, Ri;Park, Eun-Young;Pee, Jae-Hwan;Choi, Eui-Seok
    • Journal of the Korean Ceramic Society
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    • v.46 no.1
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    • pp.69-73
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    • 2009
  • We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$ particles and their surface coating with silica layers using micro emulsion method. The cobalt ferrite nanoparticles with the size 7nm are firstly prepared by thermal decomposition method. Hydrophobic nanoparticles were coated with silica using micro-emulsion method with surfactant, $NH_4OH$, and tetraethylorthosilicate (TEOS). Monodispersed and spherical silica coated cobalt ferrite nanoparticles have average particle diameter of 38 nm and narrow sized distribution.

Performance variation of Nickel-Cobalt-Manganese lithium-ion battery by cathode surface coating materials (NCM 리튬 이온 배터리의 양극 표면 코팅물질에 따른 성능변화 )

  • JinUk Yoo;Sung Gyu Pyo
    • Journal of Surface Science and Engineering
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    • v.57 no.2
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    • pp.57-70
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    • 2024
  • Nickel-cobalt-manganese (NCM) lithium-ion batteries(LIBs) are increasingly prominent in the energy storage system due to their high energy density and cost-effectiveness. However, they face significant challenges, such as rapid capacity fading and structural instability during high-voltage operation cycles. Addressing these issues, numerous researchers have studied the enhancement of electrochemical performance through the coating of NCM cathode materials with substances like metal oxides, lithium composites, and polymers. Coating these cathode materials serves several critical functions: it acts as a protection barrier against electrolyte decomposition, mitigates the dissolution of transition metals, enhances the structural integrity of the electrode, and can even improve the ionic conductivity of the cathode. Ultimately, these improvements lead to better cycle stability, increased efficiency, and enhanced overall battery life, which are crucial for the advancement of NCM-based lithium-ion batteries in high-demand applications. So, this paper will review various cathode coating materials and examine the roles each plays in improving battery performance.