• 제목/요약/키워드: ball-milling

검색결과 823건 처리시간 0.032초

WO3-CuO의 수소환원거동에 미치는 볼 밀링의 영향 (Effect of Ball-milling on Hydrogen-reduction Behavior of WO3-CuO)

  • 김대건;심우석;김영도
    • 한국재료학회지
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    • 제13권9호
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    • pp.631-634
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    • 2003
  • To fabricate W-Cu nanocomposite powder, $WO_3$-CuO powder mixture was high-energetically ball-milled and subsequently hydrogen-reduced. The effect of ball-milling on the hydrogen-reduction behavior of$ WO_3$-CuO was investigated with non-isothermal hygrometric analysis during hydrogen-reduction. Increasing the ball-milling time, the reduction peak temperatures of humidity curves were shifted to low temperature. It was considered that the reduction temperature should be decreased because the specific surface area of each oxide considerably increased with increasing the ball-milling time. In case of ball-milling for 0 h, $WO_3$and CuO were independently hydrogen-reduced and W particles were nucleated on the surface of Cu adjacent to W by CVT. However, in case of ball-milling for 50 h, the aggregates of about 200-300 nm were observed. W particles of size below 30-50 nm were homogeneously distributed with Cu in the aggregates.

탄소 나노튜브의 볼밀링 시 구조 변화 (Structural Modification of Carbon Nanotubes during Ball-milling)

  • 남혜림;안중호
    • 한국분말재료학회지
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    • 제20권4호
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    • pp.258-263
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    • 2013
  • We examined various ball-milling parameters which affect the structural and morphological modification of multi-wall carbon nanotubes. In particular, the effect of milling mode and the use of different milling agents were examined. Friction milling mode induced more structural changes than impact milling mode except the use of dry ice as a milling agent. Wet milling was helpful for reducing more effectively the agglomeration of nanotubes than dry milling. The use of hard solid particles such as silica and alumina as milling agents resulted in an effective shortening of nanotubes, but often susceptible to the amorphization and the destruction of crystallinity.

구리 관(管)의 절단(切斷) 공정(工程)중 발생한 구리칩 스크랩의 볼밀링에 의한 구리 분말(粉末) 제조(製造) 가능성(可能性) (Feasibility of Copper Powder Fabrication by Ball Milling of Copper Chip Scrap Occurred During Cutting Process of Copper Pipe)

  • 홍성현
    • 자원리싸이클링
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    • 제20권6호
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    • pp.37-42
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    • 2011
  • 구리관의 절단 공정에서 구리 칩 스크랩이 발생해왔다. 분쇄에 의하여 구리칩 스크랩을 분말화하는 가능성이 연구되었다. 본 연구에서는 로드 밀링, 수평식 볼밀링과 같은 두 가지 타입의 분쇄 방식이 적용되었다. 구리 칩은 로드 밀링에 의하여 분말 형태로 분쇄될 수 없었다. 반면에 36시간 이상 수평식 볼밀링에 의하여 구리칩은 분말로 변화하였다. 수평식 볼밀링에 의한 구리 칩의 분말로 재활용이 가능하였고 48시간 동안 밀링된 원료중 $75{\sim}150{\mu}m$ 범위의 분말은 25.3%이였다.

Ni-Al계 금속간화합물의 고주파 연소합성코팅에 미치는 볼 밀링의 영향 (Effects of Ball Milling for Elemental Powders on Ni-Al based Intermetallics Coating on Mild Steel through Induction Heating Process)

  • 이한영;박원규
    • Tribology and Lubricants
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    • 제33권6호
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    • pp.296-302
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    • 2017
  • Ball milling of elemental powders in advance and using an induction heating system for intermetallic coatings are known to enhance the reactivity of combustion synthesis. In this work, the effects of simultaneously applying these two incentive methods on the properties of intermetallic coatings are studied. Ni-Al powder compacts ball-milled with three different ball-to-powder weight ratio mixtures are synthesized and coated on mild steel by combustion synthesis in an induction heating system. Consequently, similar to an electrical heating system, the positive effects of ball milling on the combustion synthesis are confirmed in the induction heating system. The enhancement in synthetic reactivity achieved by applying the two incentive methods at the same time is greater than that by applying each incentive method separately. In particular, the enhancement is remarkable at low reaction temperature. However, there are limitations to improving the reactivity by simultaneously applying the two incentive methods to the combustion synthesis, unlike the reaction temperature. The microstructure and hardness of the coating layer are both influenced by the ball-charging ratio employed in the ball-milling process.

기계화학적 공정의 밀링 방법에 따른 W-Cu 복합분말의 미세조직 (Microstructure of W-Cu Composite Powders with Variation of Milling Method during Mechanochemical Process)

  • 이강원;김길수;김대건;김영도
    • 한국분말재료학회지
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    • 제9권5호
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    • pp.329-335
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    • 2002
  • Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using $WO_3-CuO$ mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in $H_2$ atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

기계적 합금화 방법에 의한 $Nb_3Sn$합금 제조 (The synthesis of $Nb_3Sn$ alloy powders by mechanical alloying)

  • 이성만
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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    • pp.464-467
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    • 1996
  • The microstructural evolution during mechanical alloying of Nb and Sn powders, of average composition Nb3Sn, has been investigated by X-ray diffraction(XRD) and scanning electron microscopy(SEM). Observations by SEM showed a progressive change of milling time. From the XRD studies, the structural development with milling time depends on the ball size for a given powder/ball ratio. Using a larger ball of 9.5mm diameter, the elemental powders initially alloy mechanically to form an A15 structure phase, and then amorphised with continued milling. However, in case of milling with a smaller ball of 3.968mm diameter, an amorphous phase is first formed. These results can be understood by considering the dependence of the milling energy on the ball size. The homogeneous stoichiometric $Nb_3Sn$ phase could be easily obtained by heat treatment of a supersaturated solid solution produced by MA. Heat treatment of an amorphous phase formed by MA resulted in the mixture of the $Nb_3Sn$ and $Nb_6Sn_5$ phases.

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Effects of the Mixing of an Active Material and a Conductive Additive on the Electric Double Layer Capacitor Performance in Organic Electrolyte

  • Yang, Inchan;Kwon, Soon Hyung;Kim, Bum-Soo;Kim, Sang-Gil;Lee, Byung-Jun;Kim, Myung-Soo;Jung, Ji Chul
    • 한국재료학회지
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    • 제25권3호
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    • pp.132-137
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    • 2015
  • The effects of the mixing of an active material and a conductive additive on the electrochemical performance of an electric double layer capacitor (EDLC) electrode were investigated. Coin-type EDLC cells with an organic electrolyte were fabricated using the electrode samples with different ball-milling times for the mixing of an active material and a conductive additive. The ball-milling time had a strong influence on the electrochemical performance of the EDLC electrode. The homogeneous mixing of the active material and the conductive additive by ball-milling was very important to obtain an efficient EDLC electrode. However, an EDLC electrode with an excessive ball-milling time displayed low electrical conductivity due to the characteristic change of a conductive additive, leading to poor electrochemical performance. The mixing of an active material and a conductive additive played a crucial role in determining the electrochemical performance of EDLC electrode. The optimal ball-milling time contributed to a homogeneous mixing of an active material and a conductive additive, leading to good electrochemical performance of the EDLC electrode.

Effect of high energy ball milling on the structure of iron - multiwall carbon nanotubes (MWCNT) composite

  • Kumar, Akshay;Pandel, U.;Banerjee, M.K.
    • Advances in materials Research
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    • 제6권3호
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    • pp.245-255
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    • 2017
  • High energy ball milling is employed to produce iron matrix- multiwall carbon nanotube (MWCNT) reinforced composite. The damage caused to MWCNT due to harsh ball milling condition and its influence on interfacial bonding is studied. Different amount of MWCNT is used to find the optimal percentage of MWCNT for avoidance of the formation of chemical reaction product at the matrix - reinforcement interface. Effect of process control agent is assessed by the use of different materials for the purpose. It is observed that ethanol as a process control agent (PCA) causes degradation of MWCNT reinforcements after milling for two hours whereas solid stearic acid used as process control agent, allows satisfactory conservation of MWCNT structure. It is further noted that at a high MWCNT content (~ 2wt.%), high energy ball milling leads to reaction of iron and carbon and forms iron carbide (cementite) at the iron-MWCNT interface. At low percentage of MWCNT, dissolution of carbon in iron takes place and the amount of reinforcement in iron matrix composite becomes negligibly small. However, under the present ball milling condition (ball to metal ratio~ 6:1 and 200 rpm vial speed) iron-1wt.% MWCNT composite of good interfacial bonding can retain the tubular structure of reinforcing MWCNT.

볼밀링에 의한 알루미늄 프레이크 분말 제조 (Fabrication of Aluminium Flake Powder by Ball Milling Process)

  • 이동원
    • 한국분말재료학회지
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    • 제3권3호
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    • pp.159-166
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    • 1996
  • A series of test were undertaken in order to estabilish the effect of different milling variables on dimension and quality of aluminium flake powder. Milling conditions such as initial powder size, milling container rotation speed, milling time, and ball size were varied to produce aluminium flake powder. Flake powder could then be obtained with size range from 15 $\mu$m to 40 $\mu$m with a maximum specific surface area of 5 $m^{2}$/g by controlling milling conditions. Diameter of milled powders with different milling container rotation speed and ball size were compared with that obtained from theoretical model. The best flake powder was obtained in milling condition of initial powder with average size of 19 $\mu$m, mill container rotation speed of 80 rpm, balls of 9.5 mm diameter, and milling time of 40 hours.

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

  • 안중호;장민규;오상준
    • Progress in Superconductivity
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    • 제10권1호
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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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