• Title/Summary/Keyword: wet and dry-milled powder

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Study On the Characteristics of Milled $UO_2$ Powder Prepared by Oxidation and Reduction Process (산화ㆍ환원처리된 $UO_2$ 분말의 분쇄특성 연구)

  • Lee Jae-Won;Lee Jung-Won
    • Resources Recycling
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    • v.11 no.4
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    • pp.3-10
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    • 2002
  • The characteristics of dry and wet milled powder prepared by 1 cycle OREOX (oxidation and reduction of oxide fuels) treatment were investigated using the simulated spent fuel pellet. Sintered pellets simulating spent nuclear fuel burned in reactor were fabricated from $UO_2$ powder using as a starting material in fabrication of nuclear fuel. The 1 cycle OREOX-treated powder was prepared by only one path of oxidation md reduction of the simulated pellet. Powder having average particle size of less than 1 $\mu\textrm{m}$ could be easily obtained by dry milling, but not be achieved by wet milling. And, specific surface area of dry milled pow-der was higher than that of wet milled powder. Dry milled powder formed loose agglomerate, while wet milled powder showed the shape of irregular and angular particles. Dry milled powder provided higher green density, resulting in higher sintered density of higher than 95% TD and average grain size of larger than 8 $\mu\textrm{m}$ satisfying the standard specification of sintered pellets.

[ $(Th,U)O_2$ ] Pellets: Fabrication and Thermal Properties

  • Kang Ki Won;Yang Jae Ho;Kim Keon Sik;Song Kun Woo;Lee Chan Bock;Jung Youn Ho
    • Nuclear Engineering and Technology
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    • v.35 no.4
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    • pp.299-308
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    • 2003
  • Fabrication technique of $(Th,U)O_2$ pellets has been investigated. Powder mixtures of $ThO_2\;and\;UO_2$ were milled in two different ways-dry and wet milling. Milled powder was compacted and sintered to $(Th,U)O_2$ pellets. The wet-milled powder leads to a $(Th,U)O_2$ pellet having a high sintered density and uniform distribution of U and Th, compared to the dry-milled powder. The sintered density of a $(Th,U)O_2$ pellet tends to decrease by increasing the content of $ThO_2$. The thermal conductivity of $ThO_2\;and\;(Th,U)O_2$ pellets was measured by the laser flash method. The thermal conductivity of the $ThO_2$ pellet is higher than that of the $UO_2$ pellet, and the thermal conductivities of $(Th,U)O_2$ pellets containing $65wt\%\;and\;35wt\%\;ThO_2$ pellets are lower than that of the $UO_2$ pellet.

Microstructural Characteristics of Ni/YSZ Cermet for High Temperature Electrolysis by Mechanical Alloying (기계적 합금화법으로 제조된 고온 수전해용 Ni/YSZ 전극의 미세구조 특성)

  • Park Keun-Man;Chae Ui-Seok;Hong Hyun Seon;Choo Soo-Tae
    • Korean Journal of Materials Research
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    • v.14 no.10
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    • pp.743-748
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    • 2004
  • Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by the direct ball milling of Ni and YSZ powder. The ball milling was carried out in dry process and in ethanol with varying milling time. While the dry-milling decreased the average size from 65 to $80{\mu}m$, the wet-milling decreased the average size down to $10{\mu}m$. In addition, very fine particles less than $0.1{\mu}m$ were observed in the wet-milling condition. The subsequent process of cold-pressing and sintering at $900^{\circ}C$ for 2 h did not affect the particle size of dry-milled powder. The electrical conductivity of the dry-milled Ni/YSZ cermet showed the value of $5{\times}10^{2}\;S/cm$ and this value was increased to $1.4{\times}10^{4}\;S/cm$ after the sintering at $900^{\circ}C$ for 2 h.

Synthesis of cathode material for sodium ion batteries using dry vibration milling (건식 진동밀을 이용한 나트륨이온전지 양극활물질 합성)

  • Lee, Yeon-Woo;Kim, Han-Jun;Kang, Yeonhui;Kim, Chang-Sam
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.27 no.2
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    • pp.70-74
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    • 2017
  • Two milling methods, dry vibration milling and wet ball milling, were used to prepare $Na_{2/3}(Ni_{1/3}Mn_{2/3})O_2$ powders as a cathode material for sodium ion batteries. The morphology and electrochemical property of the two powders with different milling processes were compared to each other. The particle size is less than $1{\mu}m$ in the dry vibration milled powder, while lots of larger particles than $1{\mu}m$ were found in the wet ball milled one. The single phase of $Na_{2/3}(Ni_{1/3}Mn_{2/3})O_2$ was obtained in the temperature range of $875{\sim}900^{\circ}C$. The discharge capacity and discharge voltage of the powder prepared by the dry process were higher than those of one prepared by the wet process.

Preparation of Aluminum Flake Powder by Recycling of Foil Scrap (알루미늄 호일 스크랩 재활용에 의한 플레이크 분말 제조)

  • 홍성현;김병기
    • Resources Recycling
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    • v.9 no.4
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    • pp.50-55
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    • 2000
  • Recycling technology of aluminum foil scraps into aluminum flake powder by ball milling in dry or wet conditions was studied. Aluminum foil were laminated each other, elongated through microforging by the falling balls, fragmented into small foils and then changed into flake powder during ball milling. It is also possible to recycle foil scraps with thickness less than $60\mu\textrm{m}$ into aluminum paste by wet ball milling. As initial foil thickness decreases, foil is easily milled to flake powder by wet milling in mineral spirits. the appearance and the opaque character of glass painted with aluminum paste obtained by wet milling of foils are similar to those of aluminum paste made by ball milling of gas atomized powder.

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Electrochemical Properties of Ball-milled Tin-Graphite Composite Anode Materials for Lithium-Ion Battery (볼 밀링으로 제조된 리튬이온전지용 주석-흑연 복합체 음극재의 전기화학적 특성)

  • Lee, Tae-Hui;Hong, Hyeon-A;Cho, Kwon-Koo;Kim, Yoo-Young
    • Journal of Powder Materials
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    • v.28 no.6
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    • pp.462-469
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    • 2021
  • Tin/graphite composites are prepared as anode materials for Li-ion batteries using a dry ball-milling process. The main experimental variables in this work are the ball milling time (0-8 h) and composition ratio (tin:graphite=5:95, 15:85, and 30:70 w/w) of graphite and tin powder. For comparison, a tin/graphite composite is prepared using wet ball milling. The morphology and structure of the different tin/graphite composites are investigated using X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The electrochemical properties of the samples are also examined. The optimal dry ball milling time for the uniform mixing of graphite and tin is 6 h in a graphite-30wt.%Sn sample. The electrode prepared from the composite that is dry-ball-milled for 6 h exhibits the best cycle performance (discharge capacity after 50th cycle: 308 mAh/g and capacity retention: 46%). The discharge capacity after the 50th cycle is approximately 112 mAh/g, higher than that when the electrode is composed of only graphite (196 mAh/g after 50th cycle). This result indicates that it is possible to manufacture a tin/graphite composite anode material that can effectively buffer the volume change that occurs during cycling, even using a simple dry ball-milling process.

Physicochemical properties of powdered, soft and hard type rice flour by different milling methods (제분방법에 따른 분질, 연질 및 경질미 가루의 이화학적 특성)

  • Choi, Ok Ja;Jung, Hee Nam;Shim, Ki Hoon
    • Food Science and Preservation
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    • v.22 no.2
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    • pp.174-181
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    • 2015
  • This study investigated the physicochemical properties of three different types of rice flour prepared via dry and wet milling. The powder, soft, and hard-types of rice flour were Suwon No. 542, Suwon No. 541, and Unbong No. 30, respectively. The analysis of the proximate compositions of the different types of rice flour showed that their moisture content was 7.03~7.99%, their crude protein was 7.94~8.35%, their crude lipid was 0.71~1.49% and their crude ash was 0.25~0.82%. For the Hunter's color values, the L value was highest in the wet-milled rice flour, the a value was highest in the dry-milled rice flour, and the b value was highest in the dry-milled rice flour. All the samples showed distinctive rice starch particles in the particle analysis using scanning electron microscope. The dry-milled rice flour showed the greatest amount of irregular particles and the coarsest texture. The water absorption and water solubility indices were higher in the wet-milled soft- and hard-type rice flour. The crystallinities of the samples by X-ray diffractography were all A-type, but the crystallinity of the dry-milled hard-type rice flour was higher in diffraction degree. For the amylogram properties, the wet-milled soft-type rice flour showed the highest maximum viscosity, breakdown and setback. In the meanwhile, the dry-milled soft-type rice flour showed the highest initial pasting temperature, onset, peak, and end temperatures despite of the reverse enthalpy.

Effect of Ball-Milling on the Superconducting Properties of C and C-Based Compound Doped $MgB_2$ (탄소 및 탄소화합물이 도핑된 $MgB_2$ 초전도체의 볼밀링 효과)

  • Ahn, Jung-Ho;Jang, Min-Kyu;Oh, Sang-Jun
    • Progress in Superconductivity
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    • v.10 no.1
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    • pp.17-22
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    • 2008
  • We have examined the effect of ball-milling on the superconducting properties of $MgB_2$ doped with C. The ball-milling of pre-reacted $MgB_2$ powder was carried out in dry or wet state using C or diethylenetriamine ($C_{4}H_{13}N_3$) as additives. The diethylenetriamine, whose chemical formula contains no oxygen, was chosen to avoid an excess oxidation during doping. The superconducting transition temperature (Tc) of the ball-milled or doped $MgB_2$ powders was only slightly smaller than that of undoped $MgB_2$. The critical current density (Jc) of the highly ball-milled $MgB_2$ was higher than that of C-doped $MgB_2$. The addition of diethylenetriamine was detrimental to Jc, although Tc was almost unchanged.

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Preparation and characteristics of modified Ni/YSZ cermet for high temperature electrolysis (고온 수전해 전극용 modified Ni/YSZ cermet 제조 및 전극특성)

  • Chae, Ui-Seok;Park, Geun-Man;Hong, Hyeon-Seon;Choo, Soo-Tae;Yun, Yongseung
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.2
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    • pp.98-107
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    • 2004
  • Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by dry or wet mechanical alloying methods. The Ni/YSZ composit particle was directly fabricated from the ball milling of Ni and YSZ powder or obtained from the reduction of NiO/YSZ particle after the ball milling of NiO and YSZ. In the case of the NiO/YSZ composite particle, the dry milling increased the average particle size whereas the wet milling decreased the size. The dry milling showed that fine YSZ particles were distributed over large Ni surfaces while Ni and YSZ particles similar in size were well mixed in the wet milling method. These features were the same in the Ni/YSZ composite particle prepared from Ni and YSZ powders. The electrical conductivity of the wet-milled Ni/YSZ cermet showed the highest value of $2{\times}10^2S/cm$ among the specimens and this value was increased to $1.4\times10^4S/cm$ after the sintering at $900^\circ{C}$ for 1 h.