• Title/Summary/Keyword: Co powder

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Comparison of the Kinetic Behaviors of Fe2O3 Spherical Submicron Clusters and Fe2O3 Fine Powder Catalysts for CO Oxidation

  • Yoo, Seung-Gyun;Kim, Jin-Hoon;Kim, Un-Ho;Jung, Jin-Seung;Lee, Sung-Han
    • Bulletin of the Korean Chemical Society
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    • v.35 no.5
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    • pp.1379-1384
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    • 2014

  • ${\alpha}-Fe_2O_3$ spherical particles having an average diameter of ca. 420 nm and ${\alpha}-Fe_2O_3$ fine particles (< 10 ${\mu}m$ particle size) were prepared to examine as catalysts for CO oxidation. Kinetic studies on the catalytic reactions were performed in a flow reactor using an on-line gas chromatography system operated at 1 atm. The apparent activation energies and the partial orders with respect to CO and $O_2$ were determined from the rates of CO disappearance in the reaction stage showing a constant catalytic activity. In the temperature range of $150-275^{\circ}C$, the apparent activation energies were calculated to be 13.7 kcal/mol on the ${\alpha}-Fe_2O_3$ spherical submicron clusters and 15.0 kcal/mol on the ${\alpha}-Fe_2O_3$ fine powder. The Pco and $Po_2$ dependencies of rate were investigated at various partial pressures of CO and $O_2$ at $250^{\circ}C$. Zero-order kinetics were observed for $O_2$ on both the catalysts, but the reaction order for CO was observed as first-order on the ${\alpha}-Fe_2O_3$ fine powder and 0.75-order on the ${\alpha}-Fe_2O_3$ spherical submicron clusters. The catalytic processes including the inhibition process by $CO_2$ on the ${\alpha}-Fe_2O_3$ spherical submicron powder are discussed according to the kinetic results. The catalysts were characterized using XRD (X-ray powder diffraction), FE-SEM (field emission-scanning electron microscopy), HR-TEM (high resolution-transmission electron microscopy), and $N_2$ sorption measurements.

  • https://doi.org/10.5012/bkcs.2014.35.5.1379 인용 PDF KSCI KPUBS HTML

Variation of Mechanical Properties with Powder Spraying Conditions in Mo and Co Alloy (Mo 및 Co계 분말의 용사조건에 따른 기계적 특성 변화)

  • 하국현
    • Journal of Powder Materials
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    • v.2 no.3
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    • pp.201-207
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    • 1995

  • In general, the characteristics of plasma spray coating are strongly dependent on process conditions. In this paper, Mo and Co alloy coating layers were made by plasma spraying with different spray parameters and characterized using X-ray diffraction, scanning electron microscopy(SEM), hardnass test, and wear test. It was found that the coating characteristics were mainly affected by phase composition of the powder, spray distance, arc current, and gas flow rate.

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Chemical Solution Mixing and Hydrogen Reduction Method for Fabrication of Nanostructured Fe-Co Alloy Powders (화학용액 혼합과 수소환원법을 이용한 나노구조 Fe-Co 합금분말의 제조)

  • 박광현;박현우;이백희;장시영;이정근;김영도
    • Journal of Powder Materials
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    • v.11 no.2
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    • pp.137-142
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    • 2004

  • In this study, chemical solution mixing and hydrogen reduction method was used to fabricate nanostructured $Fe_xCo_{1-x}$ alloy powders. Fe-Co chloride mixture, FeCl$_2$ and COCI$_2$ with 99.9％ purity, were reduced in hydrogen atmosphere. Nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated. Magnetic properties of fabricated $Fe_xCo_{1-x}$(x=0, 10, 30, 50, 70, 100) alloy powders with the same grain size were measured because size factor can affect magnetic properties. Coercivity of Fe-Co alloy powders were increased with increasing Co contents. Maximum value of coercivity in various Co contented Fe-Co alloy powders with similar grain size was 125 Oe at Fe$_{100}$. Saturation magnetization value at Fe$_{70}$Co$_{30}$ composition showed maximum value of 219 emu/g and saturation magnetization value decreased with increasing Co contents and minimum value of 155 emu/g was observed at Co$_{100}$.

  • https://doi.org/10.4150/KPMI.2004.11.2.137 인용 PDF KSCI