• Title/Summary/Keyword: High-energy milling

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Fabrication of Fe coated Mg Based Desulfurization Powder by Mechanical Alloying Process (기계적 합금화 공정에 의한 Fe가 코팅된 Mg 탈황 분말 제조 연구)

  • Song, Joon-Woo;Guillermo, Otaduy;Chun, Byong-Sun;Hong, Soon-Jik
    • Journal of Powder Materials
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    • v.19 no.3
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    • pp.226-231
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    • 2012
  • In this research, the coating behavior of Mg and Fe desulfurization powder fabricated by low energy and conventional planetary mill equipment was investigated as a function of milling time, which produces uniform Fe coated powders due to milling energy. Since high energy ball milling results in breaking the Fe coated Mg powders into coarse particles, low energy ball milling was considered appropriate for this study, and can be implemented in desulfurization industry widely. XRD and FE-SEM analyses were carried out to investigate the microstructure and distribution of the coating material. The thickness of the Fe coating layer reaches a maximum of 14 ${\mu}m$ at 20 milling hours. The BCC structures of Fe particles are deformed due to the slip system of Fe coated Mg particles.

Effects of High Energy Ball Milling on the Piezoelectric Properties of Lead-free (K0.44Na0.52)(Nb0.86Ta0.10)-0.04LiSbO3 Ceramics (고에너지 볼 밀링을 이용한 (K0.44Na0.52)(Nb0.86Ta0.10)-0.04LiSbO3 무연 압전 세라믹스의 특성)

  • Kim, Young-Hyeok;Heo, Dae-Young;Tai, Weon-Pil;Lee, Jae-Shin
    • Journal of the Korean Ceramic Society
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    • v.45 no.6
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    • pp.363-367
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    • 2008
  • Lead-free $(K_{0.44}Na_{0.52})(Nb_{0.86}Ta_{0.10})-0.04LiSbO_3$ piezoelectric ceramics have been synthesized by conventional sintering process and then investigated on the sintering and piezoelectric properties by high energy ball milling (HEBM) treatment. The powders milled for different time are characterized by XRD, FE-SEM. The powders are pressed into a pellet and sintered. It is found that the piezoelectric properties of sintered specimens are strongly dependent on the milling time. The piezoelectric properties are enhanced by high energy ball milling treatment. The planer electromechanical coupling factor ($k_p$) and piezoelectric constant ($d_{33}$) of a specimen sintered at $1050^{\circ}C$ are 0.44 and 267 pC/N, respectively.

A Study on Mechano-chemical Ball Milling Process for Fabricating Tungsten Disulfide Nanosheets (이황화텅스텐 나노시트 제조를 위한 기계화학적 볼밀링 공정 연구)

  • Kim, Seulgi;Ahn, Yunhee;Lee, Dongju
    • Journal of Powder Materials
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    • v.29 no.5
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    • pp.376-381
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    • 2022
  • Tungsten disulfide (WS2) nanosheets have attracted considerable attention because of their unique optical and electrical properties. Several methods for fabrication of WS2 nanosheets have been developed. However, methods for mass production of high-quality WS2 nanosheets remain challenging. In this study, WS2 nanosheets were fabricated using mechano-chemical ball milling based on the synergetic effects of chemical intercalation and mechanical exfoliation. The ball-milling time was set as a variable for the optimized fabricating process of WS2 nanosheets. Under the optimized conditions, the WS2 nanosheets had lateral sizes of 500-600 nm with either a monolayer or bilayer. They also exhibited high crystallinity in the 2H semiconducting phase. Thus, the proposed method can be applied to the exfoliation of other transition metal dichalcogenides using suitable chemical intercalants. It can also be used with high-performance WS2-based photodiodes and transistors used in practical semiconductor applications.

The Effect of Milling Conditions for Dissolution Efficiency of Valuable Metals from PDP Waste Panels (밀링조건이 사용 후 PDP패널의 유가금속 용출효율에 미치는 영향)

  • Kim, Hyo-Seob;Kim, Chan-Mi;Lee, Chul-Hee;Lee, Sung-Kyu;Hong, Hyun-Seon;Koo, Jar-Myung;Hong, Soon-Jik
    • Journal of Powder Materials
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    • v.20 no.2
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    • pp.107-113
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    • 2013
  • In this study, the microstructure and valuable metals dissolution properties of PDP waste panel powders were investigated as a function of milling parameters such as ball diameter size, milling time, and rotational speed during high-energy milling process. The complete refinement of powder could achieved at the ball diameter size of 5 mm due to sufficient impact energy and the number of collisions. With increasing milling time, the average particle size was rapidly decreased until the first 30 seconds, then decreased gradually about $3{\mu}m$ at 3 minutes and finally, increased with presence of agglomerated particles of $35{\mu}m$ at 5 minutes. Although there was no significant difference on the size of the particle according to the rotational speed from 900 to 1,100 rpm, the total valuable metals dissolution amount was most excellent at 1,100 rpm. As a result, the best milling conditions for maximum dissolving amount of valuable metals (Mg: 375 ppm, Ag 135 ppm, In: 17 ppm) in this research were achieved with 5 mm of ball diameter size, 3min of milling time, and 1,100 rpm of rotational speed.

Synthesized and sinteristics of $LaAlO_3$ ceramics from high energy ball milling powders (고에너지 볼밀로 만든 $LaAlO_3$ 분말의 합성과 소결 특성)

  • Chae, Sang-Soo;Seo, Byung-Jun;Chung, Su-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.648-651
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    • 2003
  • Fine $LaAlO_3$ powders were successfully synthesized from $La_2O_3$ and ${\gamma}-Al_2O_3$ powders milling for $10{\sim}50hrs$ via the high energy milling technique (mechanochemical methode) in room temperature and air. The particle size of $LaAlO_3$ powder were estimated from XRD patterns and SEM images to be $160{\sim}180nm$. The $LaAlO_3$ ceramics are derived for the synthesized powders (milling for 10, 30 and 50hrs) by sintering at $1400^{\circ}C$. The micrographs of grains showed a agglomeration and the degree of agglomeration increased with the milling time. The $LaAlO_3$ made from synthesized powders milling for 30hrs can be sintered to 98% of theoretical density at $1,400^{\circ}C$ for 4hrs.

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Synthesis of Extremely Fine Fe-6Al-9Si Alloy Powders by Chemical-Mechanical Hybrid Process (화학적-기계적 혼성공정에 의한 초미세 Fe-6Al-9Si 합금분말의 합성)

  • Yoon Jong Woon;Lee Kee-Sun
    • Korean Journal of Materials Research
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    • v.15 no.3
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    • pp.166-171
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    • 2005
  • Fe-6Al-9Si(N) alloy powders were synthesized by hybrid process of chemical nitrification and mechanical milling. The nitriding treatment on Fe-6Al-9Si alloy powders formed $\gamma'-Fe_4N$ phase on the powders surface. The nitriding-treated powders were pulverized by horizontal high-energy ball milling machine. The longer ball milling time tended to reduce the size of alloy powders. In ball milling for 36h, extremely fine powders with about $7\~9wt\%$ nitrogen were obtained. Through X-ray diffraction analysis on the powders, it was found out that the longer milling time caused a disappearance of the crystallinity of $\alpha-Fe$ in the powders. TEM study confirmed that the powders is comprised of a few tens nano-meter sized crystals, including $\alpha-Fe$ phase with partially $\gamma'-Fe_4N$ phase. Hysteresis curves of the synthesized powders measured by VSM revealed lower saturation magnetization and higher coercivity, which seemed to be attributed to nitrogen-impregnation and severe residual stress developed during the high energy milling. Microstructure observation on the powder annealed at 873 K for 1 h showed 10 to 20 nm sized $\alpha-Fe$ crystal. Such a enhanced crystallinity significantly increased the magnetization and decreased the coercivity, which was attributed to not only the crystallinity but also residual stress relaxation.

Nanodispersion-Strengthened Metallic Materials

  • Weissgaerber, Thomas;Sauer, Christa;Kieback, Bernd
    • Journal of Powder Materials
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    • v.9 no.6
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    • pp.441-448
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    • 2002
  • Dispersions of non-soluble ceramic particles in a metallic matrix can enhance the strength and heat resistance of materials. With the advent of mechanical alloying it became possible to put the theoretical concept into practice by incorporating very fine particles in a flirty uniform distribution into often oxidation- and corrosion- resistant metal matrices. e.g. superalloys. The present paper will give an overview about the mechanical alloying technique as a dry, high energy ball milling process for producing composite metal powders with a fine controlled microstructure. The common way is milling of a mixture of metallic and nonmetallic powders (e.g. oxides. carbides, nitrides, borides) in a high energy ball mill. The heavy mechanical deformation during milling causes also fracture of the ceramic particles to be distributed homogeneously by further milling. The mechanisms of the process are described. To obtain a homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys) a reaction milling is suitable. Dispersoid can be formed in a solid state reaction by introducing materials that react with the matrix either during milling or during a subsequent heat treatment. The pre-conditions for obtaining high quality materials, which require a homogeneous distribution of small dis-persoids, are: milling behaviour of the ductile phase (Al, Cu) will be improved by the additives (e.g. graphite), homogeneous introduction of the additives into the granules is possible and the additive reacts with the matrix or an alloying element to form hard particles that are inert with respect to the matrix also at elevated temperatures. The mechanism of the in-situ formation of dispersoids is described using copper-based alloys as an example. A comparison between the in-situ formation of dispersoids (TiC) in the copper matrix and the milling of Cu-TiC mixtures is given with respect to the microstructure and properties, obtained.

The effect of Ag addition and high-energy ball milling on Bi-2223 tapes (Ag 첨가 및 볼밀링에 의한 Bi-2223/Ag 초전도 선재의 특성변화)

  • 김영순;오상수;류강식;정대영;안중호
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2000.02a
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    • pp.101-103
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    • 2000
  • In the present work, we have investigated the combined effect of high-energy milling and Agb addition on microstructure and superconducting properties for Bi-2223/Ag. tape. The addition of siver plays an important role in enhancing liquid phase formation, Resulting in densification and cracking during solidification. Further study is needed for the optimization of Ag content and heat-treatment which can reduce the cracking.

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Effects of Composition and Additives on the Mechanical Characteristics of 3Y-TZP (3Y-TZP의 기계적 특성에 미치는 산화물 조성 및 첨가제의 영향)

  • Park, Mi-Jung;Yang, Seong-Koo;Kang, Jong-Bong
    • Journal of the Korean Ceramic Society
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    • v.43 no.10 s.293
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    • pp.640-645
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    • 2006
  • Monoclinic zirconia and yttria were mixed with a stoichiometric composition of 3Y-TZP (3 mol% Yttria-stabilized Tetragonal Zirconia Polycrystal). The specimen was sintered at 1350$\sim$1450$^{\circ}C$ and mechanical characterization and microstructure analysis were conducted. Microhardness and fracture toughness were shown as 1357.4 Hv and 8.56 MPa $m^{1/2}$. respectively. Without alumina, they were 1311 Hv and 10.02 MPa $m^{1/2}$ respectively. By mixing two different oxides, it was possible to obtain high values of microhardness and fracture toughness. It was possible that was turned out nano-scale particle using the co-milling of high mechanical energy.