• Title/Summary/Keyword: high energy ball milling

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Effect of Initial Silicon Scrap Size on Powder Refining Process During High Energy Ball Milling (HEBM) (폐실리콘의 고에너지 밀링 과정에서 초기 입자 크기가 분말의 미세화에 미치는 효과)

  • Song, Joon-Woo;Kim, Hyo-Seob;Kim, Sung-Shin;Koo, Jar-Myung;Hong, Soon-Jik
    • Journal of Powder Materials
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    • v.17 no.3
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    • pp.242-250
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    • 2010
  • In this research, the optimal manufacturing conditions of fine Si powders from Si scrap were investigated as a function of different initial powder size using the high-energy ball milling equipment, which produces the fine powder by means of an ultra high-energy within a short duration. The morphological change of the powders according to the milling time was observed by Scanning electron microscopy (SEM). With the increasing milling time, the size of Si powder was decreased. In addition, more energy and stress for milling were required with the decreasing initial powder size. The refinement of Si scrap was rapidly carried out at 10min ball milling time. However, the refined powder started to agglomerate at 30 min milling time, while the powder size became uniform at 60 min milling time.

Effect of High-energy Ball Milling on the Mg Alloy Powders under Alcohol Protection

  • Li, Gang;Liu, Xingxing;Guo, Qi;Tang, Jianren;Yan, Biao
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1264-1265
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    • 2006
  • Study about the feasibility and effect of high-energy ball milling on a specific Mg alloy under protection medium of alcohol was presented via comparing with conventional vacuum milling. More fine particles with wider powder size distribution but more irregular shape were shown of the powder milled under alcohol. No obvious oxide was revealed from the two kinds of Mg alloy powders with limited milling time. And since slip induced in a preferential direction, the (002) texture was formed in the Mg alloy powders at the initial stage of alcohol milling. More O and Fe contaminants were introduced into the powders milled under alcohol according to the EDS analysis.

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Synthesis and Microstructure of Fe-Base Superalloy Powders with Y-Oxide Dispersion by High Energy Ball Milling (고에너지 볼 밀링을 이용한 Y-산화물 분산 Fe-기초내열합금 분말의 합성 및 미세조직 특성)

  • Yim, Da-Mi;Park, Jong Kwan;Oh, Sung-Tag
    • Korean Journal of Materials Research
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    • v.25 no.8
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    • pp.386-390
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    • 2015
  • Fe-base superalloy powders with $Y_2O_3$ dispersion were prepared by high energy ball milling, followed by spark plasma sintering for consolidation. High-purity elemental powders with different Fe powder sizes of 24 and 50 mm were used for the preparation of $Fe-20Cr-4.5Al-0.5Ti-O.5Y_2O_3$ powder mixtures (wt%). The milling process of the powders was carried out in a horizontal rotary ball mill using a stainless steel vial and balls. The milling times of 1 to 5 h by constant operation (350 rpm, ball-to-powder ratio of 30:1 in weight) or cycle operation (1300 rpm for 4 min and 900 rpm for 1 min, 15:1) were applied. Microstructural observation revealed that the crystalline size of Fe decreased with an increase in milling time by cyclic operation and was about 15 nm after 3 h, forming a FeCr alloy phase. The cyclic operation had an advantage over constant milling in that a smaller-agglomerated structure was obtained. The milled powders were sintered at $1100^{\circ}C$ for 30 min in vacuum. With an increase in milling time, the sintered specimen showed a more homogeneous microstructure. In addition, a homogenous distribution of Y-compound particles in the grain boundary was confirmed by EDX analysis.

Spark Plasma Sintering of Stainless Steel Powders Fabricated by High Energy Ball Milling

  • Chang, Si Young;Oh, Sung-Tag;Suk, Myung-Jin;Hong, Chan Seok
    • Journal of Powder Materials
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    • v.21 no.2
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    • pp.97-101
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    • 2014
  • The 304 stainless steel powders were prepared by high energy ball milling and subsequently sintered by spark plasma sintering, and the microstructural characteristics and micro-hardness were investigated. The initial size of the irregular shaped 304 stainless steel powders was approximately 42 ${\mu}m$. After high energy ball milling at 800 rpm for 5h, the powders became spherical with a size of approximately 2 ${\mu}m$, and without formation of reaction compounds. From TEM analysis, it was confirmed that the as-milled powders consisted of the aggregates of the nano-sized particles. As the sintering temperature increased from 1073K to 1573K, the relative density and micro-hardness of sintered sample increased. The sample sintered at 1573K showed the highest relative density of approximately 95% and a micro-hardness of 550 Hv.

Sintering Behavior of Nano-sized Gd2O3-doped CeO2 Powder Prepared by A High Energy Ball Milling (고에너지 볼밀링에 의해 제조된 Gd2O3-doped CeO2 나노분말의 소결 거동에 관한 연구)

  • Ryu, Sung-Soo;Kim, Hyung-Tae
    • Journal of Powder Materials
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    • v.15 no.4
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    • pp.302-307
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    • 2008
  • $Gd_2O_3$-doped $CeO_2$(GDC) solid solutions have been considered as a promising materials for electrolytes in intermediate-temperature solid oxide fuel cells. In this study, the nano-sized GDC powder with average panicle size of 69nm was prepared by a high energy ball milling process and its sintering behavior was investigated. Heat-treatment at $1200^{\circ}C$ of nano-sized GDC powder mixture led to GDC solid-solution. The enhanced densification over 96% of relative density was obtained after sintering at $1300^{\circ}C$ for 2h. It was found that the sinterability of GDC powder could be significantly improved by the introduction of a high energy ball milling process.

Synthesis of Nanocrystalline BaTiO3 Powder by the Combination of High Energy Ball Milling of BaCO3-TiO2 Mixture and Solid-State Reaction (고에너지 볼밀링된 BaCO3와 TiO2 혼합분말의 고상반응에 의한 나노결정 BaTiO3 분말 합성)

  • Ryu, Sung-Soo
    • Journal of Powder Materials
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    • v.19 no.4
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    • pp.310-316
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    • 2012
  • Nanocrystalline $BaTiO_3$ powder could be synthesized by solid-state reaction using the mixture which was prepared by a high energy milling process in a bead mill for $BaCO_3$ and nanocrystalline $TiO_2$ powders mixture. Effect of the milling time on the powder characteristic of the synthesized $BaTiO_3$ powder was investigated. Nanocrystalline $BaTiO_3$ with a particle size of 50 nm was obtained at $800^{\circ}C$. High tetragonal $BaTiO_3$ powder with a tetragonality(=c/a) of 1.009 and a specific surface area of $7.6m^2/g$ was acquired after heat-treatment at $950^{\circ}C$ for 2 h. High energy ball milling was effective in decreasing the reaction temperature and increasing the tetragonality.

Effect of Process Parameters on Microstructure and Magnetic Properties of Sm-Co Alloy Powder Prepared by High Energy Ball Milling (고에너지 볼밀링된 Sm-Co 합금 분말의 미세조직 및 자성특성에 미치는 공정변수의 영향)

  • Kim, Bo-Sik;Chang, Si-Young
    • Journal of Powder Materials
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    • v.17 no.2
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    • pp.130-135
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    • 2010
  • Sm-16.7wt%Co alloy powders were prepared by high energy ball milling under the conditions of various milling time and the content of process control agent (PCA), and their microstructure and magnetic properties were investigated to establish optimum processing conditions. The initial powders employed showed irregular shape and had a size ranging from 5 to $110\;{\mu}m$. After milling for 5 h, the shape of powders changed to round shape and their mean powder size was approximately $5\;{\mu}m$, which consisted of the agglomerated nano-sized particles with 15 nm in diameter. The coercivity was reduced with increasing the milling time, whereas the saturation magnetization increased. As the content of PCA increased, the powder size minutely decreased to approximately $7\;{\mu}m$ at the PCA content of 10 wt%. The XRD patterns showed that the main diffraction peaks disappeared apparently after milling, indicating the formation of amorphous structure. The measured values of coercivity were almost unchanged with increasing the content of PCA.

Simple Synthesis of SiOx by High-Energy Ball Milling as a Promising Anode Material for Li-Ion Batteries

  • Sung Joo, Hong;Seunghoon, Nam
    • Corrosion Science and Technology
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    • v.21 no.6
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    • pp.445-453
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    • 2022
  • SiOx was prepared from a mixture of Si and SiO2 via high-energy ball milling as a negative electrode material for Li-ion batteries. The molar ratio of Si to SiO2 as precursors and the milling time were varied to identify the synthetic condition that could exhibit desirable anode performances. With an appropriate milling time, the material showed a unique microstructure in which amorphous Si nanoparticles were intimately embedded within the SiO2 matrix. The interface between the Si and SiO2 was composed of silicon suboxides with Si oxidation states from 0 to +4 as proven by X-ray photoelectron spectroscopy and electrochemical analysis. With the addition of a conductive carbon (Super P carbon black) as a coating material, the SiOx/C manifested superior specific capacity to a commercial SiOx/C composite without compromising its cycle-life performance. The simple mechanochemical method described in this study will shed light on cost-effective synthesis of high-capacity silicon oxides as promising anode materials.

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.

Prepration and Properties of Blue Tungsten Oxide Nanopowders by High Energy Ball-Mill (고 에너지 볼밀을 이용한 Blue 텅스텐산화물 나노입자의 제조와 특성)

  • Kim, Myung-Jae;Lee, Kwang-Seok;Kim, Kyung-Nam
    • Korean Journal of Materials Research
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    • v.31 no.1
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    • pp.23-28
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    • 2021
  • The purpose of this study is to prepare WO3 nanopowders by high-energy milling in mixture gas (7 % H2+Ar) with various milling times (10, 30, and 60 min). The phase transformation, particle size and light absorption properties of WO3 nanopowders during reduction via high-energy milling are studied. It is found that the particle size of the WO3 decreases from about 30 ㎛ to 20 nm, and the grain size of WO3 decreases rapidly with increasing milling time. Furthermore, the surface of the particles due to the pulverization process is observed to change to an amorphous structure. UV/Vis spectrophotometry shows that WO3 powder with increasing milling times (10, 30, 60 min) effectively extends the light absorption properties to the visible region. WO3 powder changes from yellow to gray and can be seen as a phenomenon in which the progress of the color changes to blue. The characterization of WO3 is performed by high resolution X-ray diffractometry, Field emission scanning electron microscopy, Transmission electron microscopy, UV/Vis spectrophotometry and Particle size analysis.