• Title/Summary/Keyword: Aluminum Oxide Powder

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Synthesis and Compaction of Al-based Nanopowders by Pulsed Discharge Method

  • Rhee, Chang-Kyu;Lee, Geun-Hee;Kim, Whung-Whoe
    • Journal of Powder Materials
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    • v.9 no.6
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    • pp.433-440
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    • 2002
  • Synthesis and compaction of Al-base nano powders by pulsed discharge method were investigated. The aluminum based powders with 50 to 200 nm of diameter were produced by pulsed wire evaporation method. The powders were covered with very thin oxide layer. The perspective process for the compaction and sintering of nanostructured metal-based materials stable in a wide temperature range can be seen in the densification of nano-sized metal powders with uniformly distributed hard ceramic particles. The promising approach lies in utilization of natural uniform mixtures of metal and ceramic phases, e.g. partially oxidized metal powders as fabricated in our synthesis method. Their particles consist of metal grains coated with oxide films. To construct a metal-matrix material from such powder, it is necessary to destroy the hard oxide coatings of particles during the compaction process. This goal was realized in our experiments with intensive magnetic pulsed compaction of aluminum nanopowders passivated in air.

Cold Compaction Behavior of Nano and Micro Aluminum Powder under High Pressure

  • Kim, Dasom;Park, Kwangjae;Kim, Kyungju;Cho, Seungchan;Hirayama, Yusuke;Takagi, Kenta;Kwon, Hansang
    • Composites Research
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    • v.32 no.3
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    • pp.141-147
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    • 2019
  • In this study, micro-sized and nano-sized pure aluminum (Al) powders were compressed by unidirectional pressure at room temperature. Although neither type of Al bulk was heated, they had a high relative density and improved mechanical properties. The microstructural analysis showed a difference in the process of densification according to particle size, and the mechanical properties were measured by the Vickers hardness test and the nano indentation test. The Vickers hardness of micro Al and nano Al fabricated in this study was five to eight times that of ordinary Al. The grain refinement effect was considered to be one of the strengthening factors, and the Hall-Petch equation was introduced to analyze the improved hardness caused by grain size reduction. In addition, the effect of particle size and dispersion of aluminum oxide in the bulk were additionally considered. Based on these results, the present study facilitates the examination of the effect of particle size on the mechanical properties of compacted bulk fabricated by the powder metallurgy method and suggests the possible way to improve the mechanical properties of nano-crystalline powders.

(A) Study on the Mechanical Properties Improvement of Thermite Welded Zone of Railroad Rail (철도레일 테르밋 용접부의 기계적 특성 향상 방안에 관한 연구)

  • Choi, Sang-Kyu;Park, Sung-Sang;Baek, Eung-Ryul;Chun, Bong-Gil
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2101-2106
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    • 2011
  • It is reported that about more than 45% of damage shown in railroad rails include breakage of rail end which cross the center of Thermit welded zone. Thermite welding is always accompanied by numerous aluminum oxide and secondary inclusions, which may have a negative influence on the ductility and toughness of the weld metal. In this study the aluminum powder recycled by waste aluminum can was used for iron oxide generated after the process of welding rod and the remain aluminum was reduced by minimizing the quantity of aluminum. And complete dissolution was induced by using ferro Mn powder as the additive element. This study reviewed the applicability of heat treatment in the welded zone of rail using ceramic heating pad by carrying it out. This study could observe the improvement of the mechanical characteristics (UTS and elongation) and the changes of failure mechanism from brittleness to ductility. It could be found that improved strength and elongation result from pearilte fine structure.

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A novel approach for manufacturing oxide dispersion strengthened (ODS) steel cladding tubes using cold spray technology

  • Maier, Benjamin;Lenling, Mia;Yeom, Hwasung;Johnson, Greg;Maloy, Stuart;Sridharan, Kumar
    • Nuclear Engineering and Technology
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    • v.51 no.4
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    • pp.1069-1074
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    • 2019
  • A novel fabrication method of oxide dispersion strengthened (ODS) steel cladding tubes for advanced fast reactors has been investigated using the cold spray powder-based materials deposition process. Cold spraying has the potential advantage for rapidly fabricating ODS cladding tubes in comparison with the conventional multi-step extrusion process. A gas atomized spherical 14YWT (Fe-14%Cr, 3%W, 0.4%Ti, 0.2% Y, 0.01%O) powder was sprayed on a rotating cylindrical 6061-T6 aluminum mandrel using nitrogen as the propellant gas. The powder lacked the oxygen content needed to precipitate the nanoclusters in ODS steel, therefore this work was intended to serve as a proof-of-concept study to demonstrate that free-standing steel cladding tubes with prototypical ODS composition could be manufactured using the cold spray process. The spray process produced an approximately 1-mm thick, dense 14YWT deposit on the aluminum-alloy tube. After surface polishing of the 14YWT deposit to obtain desired cladding thickness and surface roughness, the aluminum-alloy mandrel was dissolved in an alkaline medium to leave behind a free-standing ODS tube. The as-fabricated cladding tube was annealed at $1000^{\circ}C$ for 1 h in an argon atmosphere to improve the overall mechanical properties of the cladding.

Synthesis of Aluminum Nitride Nanopowders by Carbothermal Reduction of Aluminum Oxide and Subsequent In-situ Nitridization (산화알루미늄 분말의 탄소열환원 및 직접 질화반응을 통한 질화알루미늄 나노분말의 합성)

  • Seo, Kyung-Won;Lee, Seong-Yong;Park, Jong-Ku;Kim, Sung-Hyun
    • Journal of Powder Materials
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    • v.13 no.6 s.59
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    • pp.432-438
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    • 2006
  • Aluminum nitride (AlN) nanopowders with low degree of agglomeration and uniform particle size were synthesized by carbothermal reduction of alumina and subsequent direct nitridization. Boehmite powder was homogeneously admixed with carbon black nanopowders by ball milling. The powder mixture was treated under ammonia atmosphere to synthesize AlN powder at lour temperature. The effect of process variables such as boehmite/carbon black powder ratio, reaction temperature and reaction time on the synthesis of AlN nanopowder was investigated.

Fabrication and Growth of Ni Nanowires by using Anodic Aluminum Oxide(AAO) Template via Electrochemical Deposition (전기화학증착법으로 양극산화 알루미늄(AAO) 템플레이트를 이용한 Ni 나노와이어의 제조 및 성장에 관한 연구)

  • Sim, Seong-Ju;Cho, Kwon-Koo;Kim, Yoo-Young
    • Journal of Powder Materials
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    • v.18 no.1
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    • pp.49-55
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    • 2011
  • Ni nanowires were fabricated using anodic aluminum oxide (AAO) membrane as a template by electrochemical deposition. The nanowires were formed within the walls of AAO template with 200 nm in pore diameter. After researching proper voltage and temperature for electrochemical deposition, the length of Ni nanowires was controlled by deposition time and the supply of electrolyte. The morphology and microstructure of Ni nanowires were investigated by field emission scanning electron microscope (FE-SE), X-ray diffraction (XRD) and transmission electron microscope (TEM).

Degassing of Aluminum and Aluminum Alloy Powders as Studied by Gas Chromatography

  • Watanabe, Ryuzo;Choi, Duk-Sun;Kawasaki, Akira
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.716-717
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    • 2006
  • Gas release behavior from aluminum and Al 7075 alloy powders during heating in argon was investigated by in-situ gas chromatography. Water vapor, hydrogen, carbon mono-oxide were detected as individual evolution spectra against heating temperature and time. The mechanisms of water and hydrogen evolutions were studied in detail for the determination of effective degassing condition. Magnesium in the alloy powder was found to lower the hydrogen evolution temperature to enhance overall hydrogen release.

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Ignition Characteristics of Aluminum Metal Powder Fuel with Thermal Plasma (플라즈마를 이용한 분말형 금속 연료 알루미늄의 점화 특성)

  • Lee, Sang-Hyup;Lim, Ji-Hwan;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.737-744
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    • 2011
  • The success of continuous aluminum powder combustion with steam plasma is different from hydrocarbon ignition source. Ignition characteristics of aluminum powder with high temperature thermal plasma is studied with oxidizer-free environment. Experiment with argon plasma has same temperature conditions at 4500 K and particle feeding condition for previous combustion test with steam plasma and swirl combustor. The temperature of the plasma was measured using Optical Emission Spectroscopy method. Ignition characteristics were analyzed by SEM image and EDS. Aluminum powder with plasma has rapid evaporation mechanism contrast to hydrocarbon ignition source. It enhances to aluminum powder effective ignition characteristics.

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Study on Hardness and Corrosion Resistance of Magnesium by Anodizing and Sealing Treatment With Nano-diamond Powder (양극산화와 나노 다이아몬드 분말 봉공처리에 의한 마그네슘의 경도와 부식에 관한 연구)

  • Kang, Soo Young;Lee, Dae Won
    • Journal of Powder Materials
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    • v.21 no.4
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    • pp.260-265
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    • 2014
  • In this study, in order to increase surface ability of hardness and corrosion of magnesium alloy, anodizing and sealing with nano-diamond powder was conducted. A porous oxide layer on the magnesium alloy was successfully made at $85^{\circ}C$ through anodizing. It was found to be significantly more difficult to make a porous oxide layer in the magnesium alloy compared to an aluminum alloy. The oxide layer made below $73^{\circ}C$ by anodizing had no porous layer. The electrolyte used in this study is DOW 17 solution. The surface morphology of the magnesium oxide layer was investigated by a scanning electron microscope. The pores made by anodizing were sealed by water and aqueous nano-diamond powder respectively. The hardness and corrosion resistance of the magnesium alloy was increased by the anodizing and sealing treatment with nano-diamond powder.

Synthesis and Characterization of Zinc Phosphate Cement Powder and Cement-forming Liquid

  • Park, Choon-Keun
    • The Korean Journal of Ceramics
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    • v.3 no.4
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    • pp.269-273
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    • 1997
  • Chemical composition of cement powder influences the setting time and early compressive strength development. The setting time increases as the amounts of zinc oxide and magnesium oxide are increased. For one day compressive strength development, a cement powder with a composition 90% ZnO, 8% MgO and 2% silica resulted in the highest strength (greater than 1, 090 kg/$\textrm{cm}^2$). Cement-forming liquids also need to be buffered, with both aluminum and zinc ions, for a good consistency and a higher strength of the zinc phosphate cement. These liquids control the setting reactions.

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