• Title/Summary/Keyword: Cobalt aluminate

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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.

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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Color Simulation to Demonstrate the Effects of the Filter Layer with $CoAl_2O_4$ on Inner Face of CRT Panel

  • Kim, Sang-Mun
    • Journal of Information Display
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    • v.6 no.3
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    • pp.26-29
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    • 2005
  • Nanosize cobalt aluminate($CoAl_2O_4$) power was coated as filter layer for us to improve the color purity and contrast performances on the inner face of CRT panel. We simulated color properties by measuring the transmittance and thickness of the coated filter layer. Contrast performance could be improved and color gamut was also changed by the selective light absorption of filter layer at 580${\sim}$605 nm.

The effects of the filter layer with $CoAl_2O_4$ on inner face of CRT Panel.

  • Kim, Sang-Mun;Koh, Nam-Je
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1175-1178
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    • 2005
  • Nanosize cobalt aluminate($CoAl_2O_4$) power as filter layer was coated to improve the color purityand contrast performances on inner face of CRT panel. We simulated color properties by measuring the transmittance and thickness of the coated filter layer. Contrast performance could be improved and color gamut was also changed because of the selective light absorption of filter layer at $580{\sim}605\;nm$.

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The Powder Preparation of Blue Cobalt Aluminate at 210 °C Using the Malonate Method

  • Lee, Gong-Yeol;Lee, Dong-Hoon;Kim, Hong-Gun;Kim, Yoo-Young
    • Bulletin of the Korean Chemical Society
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    • v.31 no.1
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    • pp.47-51
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    • 2010
  • A powder, containing 80 percent of blue cobalt aluminate $(CoAl_2O_4)$ crystallites, was synthesized at $210 ^{\circ}C$ using a (metal nitrate-malonic acid-ammonium hydroxide-ammonium nitrate) system. The optimal amount of concentrated ammonia water and initial decomposition temperature were determined for the blue $CoAl_2O_4$ crystallites preparation. Three $CoAl_2O_4$ precursor pastes, corresponding to the various amounts of concentrated ammonia water, were prepared by evaporating the initial solutions in an electric furnace fixed at $80 ^{\circ}C$ under a vacuum of 25 torr. The initial solution was used to dissolve the starting materials. The powder with the maximum content (80%) of blue $CoAl_2O_4$ crystallites was prepared when the prepared precursor was decomposed at $210 ^{\circ}C$. The blue $CoAl_2O_4$ crystallite content in the prepared sample decreased with increasing initial decomposition temperature. For 0.2 mole of the $Al^{3+}$ ion, the chemical compositions of the precursor corresponded to molar ratios of 0.4, 1.40, 2.56 and 2.00 for the $Co^{2+}$ ion, malonic acid, ammonia and ammonium nitrate per mole of the $Al^{3+}$ ion, respectively. The blue $CoAl_2O_4$ crystallite content in the sample decreased with the amount of ammonia deviated from the optimal value. The characteristics of the powders were examined using X-ray diffraction, optical microscopy, Fourier transformation infrared spectroscopy and the Brunauer-Emmett-Teller technique.

Investigating the Colour Difference of Old and New Blue Japanese Glass Pigments for Artistic Use

  • Chua, Lynn;Quan, Seah Zi;Yan, Gao;Yoo, Woo Sik
    • Journal of Conservation Science
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    • v.38 no.1
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    • pp.1-13
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    • 2022
  • Colour consistency is an important consideration when selecting pigments used on works of art. In this study, we analyse the colour difference between two sets of synthetic blue glass pigments acquired at least 8 years apart from the same manufacturer in Japan. The old pigment set (unused, dry powder with four different grain sizes) appears faded compared to the new set. These pigments are made available for artistic use, commonly in Nihonga or Japanese paintings. Raman spectroscopy and SEM-EDS results characterize these pigments as cobalt aluminate spinels dissolved in leaded glaze, a special class of complex coloured inorganic pigments that is not well-understood in the field of conservation. Colour difference between the old and new pigments with four different grain sizes were quantified by analysing photomicrographs with image analysis software. Blue pigments with coarse and extremely fine grains showed significant colour change compared to pigments with medium and fine grain sizes. The high occurrence of crystallites in the finer grains give a final colour that is bluer and lighter. Possible causes for the colour difference including manufacturing methods and storage environment are discussed.

Additive Manufacturing of Various Ceramic Composition Using Inkjet Printing Process (잉크젯 프린팅을 이용한 연속 조성 세라믹 화합물 구조체 형성)

  • Park, Jae-Hyeon;Choi, Jung-Hoon;Hwang, Kwang-Taek;Kim, Jin-Ho
    • Korean Journal of Materials Research
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    • v.30 no.11
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    • pp.627-635
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    • 2020
  • 3D printing technology is a processing technology in which 3D structures are formed by fabricating multiple 2D layers of materials based on 3D designed digital data and stacking them layer by layer. Although layers are stacked using inkjet printing to release various materials, it is still rare for research to successfully form a product as an additive manufacture of multi-materials. In this study, dispersion conditions are optimized by adding a dispersant to an acrylic monomer suitable for inkjet printing using Co3O4 and Al2O3. 3D structures having continuous composition composed of a different ceramic material are manufactured by printing using two UV curable ceramic inks whose optimization is advanced. After the heat treatment, the produced structure is checked for the formation and color of the desired crystals by comparing the crystalline analysis according to the characteristics of each part of the structure with ceramic pigments made by solid phase synthesis method.

Preparation and characterization of CoAl2O4 blue ceramic nano pigments by attrition milling (어트리션밀을 이용한 CoAl2O4 나노 무기 안료의 제조 및 특성 평가)

  • Lee, Ki-Chan;Yoon, Jong-Won;Kim, Jin-Ho;Hwang, Kwang-Taek;Han, Kyu-Sung
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.23 no.5
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    • pp.255-264
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    • 2013
  • Cobalt aluminate ($CoAl_2O_4$) is a highly stable pigment with excellent resistance to light, weather, etc., which has resulted in widespread use as a ceramic pigment. Due to the unique optical characteristics, $CoAl_2O_4$ is generally used as a coloring agent to decorate porcelain products, glass, paints and plastics. Here, $CoAl_2O_4$ pigments were synthesized by polymerized complex method and solid state reaction. Then $CoAl_2O_4$ pigment were grinded using the attrition milling with 1 mm size zirconia ball for 3 hours. The attrition milling process was performed at the constant speed of 800 rpm and ball to powder weight ratio (BPR) was 100 : 1. The characteristics of synthesized pigment were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), particle size analyser (PSA) and CIE $L^*a^*b^*$. The XRD patterns of $CoAl_2O_4$ show single phase spinel structure. The particle size of $CoAl_2O_4$ measured by FE-SEM, TEM and PSA analysis was in the range of 100~200 nm. The blue color of obtained $CoAl_2O_4$ pigments could be confirmed through CIE $L^*a^*b^*$ measurement.

Glycerol Steam Reforming for Hydrogen Production on Metal-ceramic Core-shell CoAl2O4@Al Composite Structures (금속-세라믹 Core-Shell CoAl2O4@Al 구조체를 적용한 불균일계 촉매의 글리세롤 수소전환 반응특성)

  • Kim, Jieun;Lee, Doohwan
    • Clean Technology
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    • v.21 no.1
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    • pp.68-75
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    • 2015
  • In this study, we investigated the structure and properties of a highly heat conductive metal-ceramic core-shell CoAl2O4@Al micro-composite for heterogeneous catalysts support. The CoAl2O4@Al was prepared by hydrothermal surface oxidation of Al metal powder, which resulted in the structure with a high heat conductive Al metal core encapsulated by a high surface area CoAl2O4 shell. For comparison, CoAl2O4 was also prepared by co-precipitation method and also utilized for a catalyst support. Rh catalysts supported on CoAl2O4@Al and CoAl2O4 were prepared by incipient wetness impregnation and characterized by N2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), CO chemisorption, and temperature-programmed reduction (TPR). The properties of catalysts were investigated for glycerol steam reforming reaction for hydrogen production at 550 ℃. Rh/CoAl2O4@Al exhibited about 2.8 times higher glycerol conversion turnover frequency (TOF) than Rh/CoAl2O4 due to facilitated heat transport through the core-shell structure. The CoAl2O4@Al and CoAl2O4 also showed some catalytic activities due to a partial reduction of Co on the support, and a higher catalytic activity was also found on the CoAl2O4@Al core-shell than CoAl2O4. These catalysts, however, displayed deactivation on the reaction stream due to carbon deposition on the catalysts surface.