• Title, Summary, Keyword: shape control of powder

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Shape Control of Anodic Aluminum Oxide and Effect as Support of Silicon Powder Electrode (양극산화알루미늄의 형상제어와 이를 이용한 실리콘 분말 전극 지지체 효과)

  • Song, Ju-Seok;Ha, Jong-Keun;Kim, Yoo-Young;Park, Dong-Kyu;Ahn, In-Shup;Ahn, Jou-Hyeon;Cho, Kwon-Koo
    • Journal of Korean Powder Metallurgy Institute
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    • v.22 no.4
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    • pp.240-246
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    • 2015
  • Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at $4^{\circ}C$. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.

Particle Size and Shape Analysis : The Key to Success in Metal Powder Production

  • Pankewitz, Axel;Park, Yong-Jae
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.702-703
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    • 2006
  • The particle size distribution and shape are among the important parameters for characterisation of quality of metal powders. Specific material properties such as ability to flow, reactivity as well as compressibility and its hardening potentials hence the most important characteristics of sintered metals - are determined by the size distribution and shape. The correct particle size distribution and particle shape information are the key to best product quality in atomisation processes of aluminium, milling of pure metals and other processes. This paper presents state-of-the-art technology for characterization of particle size distribution and shape.

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Manufacture of Precsion Model Using Laser Melting Process (레이저 용융 적층 공정을 이용한 정밀 형상 제작)

  • 김재도;전병철;권택열;이영곤;신동훈
    • Journal of Korean Society of Laser Processing
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    • v.3 no.3
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    • pp.21-29
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    • 2000
  • For the direct metal shape processing the powder feed device which is different from the widely used in rapid prototyping. is developed, The three dimensional object is shaped with the melting metal powder. The developed research has applied to rapid prototyping in ultraprecision for MEMS and medical science fields required of rapid manufacture of complex shape. The goal of this study make 3D model which has precision accuracy. Powder spreading apparatus has been more improved because that the control of powder spread is very important in layer manufacturing. It consists of the vibration motor, nozzle and tube which supplies various metal powder. This apparatus could control the spreading velocity that could control powder spreading thickness. Laser on/off switch was adapted because laser scanning velocity must be preserved constantly to prevent heat transformation of laser overheating. The error between sintered thickness md experimental one occurred by shrinkage in sintering melting process. The problem of heat transformation was solved by On/Off switching system.

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Fabrication of Mo based Thermal Spray Composite Powder by Self- propagating High- temperature Synthesis (SHS 합성에 의한 몰리브덴계 용사용 복합분말의 제조)

  • Park, Je-Sin;Sim, Geon-Ju
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.763-768
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    • 2001
  • Molybdenum-based thermal spray powder is widely used for coating the moving parts of the internal combustion engines due to its excellent wear resistance. A composite powder of the $Mo_{40}(Al_{1-x}Si_x)_{60}$ system was synthesized using the SHS method. The synthesized bulk was pulverized and specially treated to produce thermal spray powder. It was found that the synthesis reaction consisted of two-steps: the formation of $Al_8/Mo_3$ and the formation of Mo(Al,Si)$_2$. Both the temperature and the rate of the SHS reaction linearly increased with the increase of the value of x in $Mo_{40}(Al_{1-x}Si_x)_{60}$, The temperature and the rate of the reaction were also affected by the compacting density of the specimens, exhibiting the maximum valves at 62% and 60%, respectively. Since spherical shape is advantageous to the thermal spraying process, shape-control of the powder was attempted with PVA as a binding additive, resulting in the successful production of almost perfectly spherical powder of 80 $\mu\textrm{m}$ Ø$(d_{50})$ mean particle size.

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Prediction of Packing Density of Milled Powder Based on Packing Simulation and Particle Shape Analysis

  • Amano, Yuto;Itoh, Takashi;Terao, Hoshiaki;Kanetake, Naoyuki
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.1254-1255
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    • 2006
  • For precise property control of sintered products, it is important to understand accurately the packing density of the powder. We developed a packing simulation program that could make a packed bed of spherical particles having particle size distribution. In addition, the influence of the particle shape of the actual powder on the packing density was quantitatively analyzed. The predicted packing densities corresponded well to the actual data.

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Preparation and Magnetic Properties of Acicular Ba-Ferrite Powder

  • Lee, Hak-Dong;Nam, Joong-Hee;Oh, Jae-Hee
    • Journal of Magnetics
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    • v.5 no.2
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    • pp.40-43
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    • 2000
  • Acicular $\alpha-FeOOH\; and\; Ba(OH)_2\cdot8H_2O$ are starting materials in this study. This paper presents the characteristics of the contents of citric acid and heating condition for preparing acicular barium ferrite powder. They control particle shape, crystalline phase, magnetic properties of acicular barium ferrite powder So the effects of the contents of citric acid and heating condition are studied. The experimental condition for starting materials were 800~1000$\circ C$ in firing and 0~40 wt% citric acid, respectively, Ba-ferrite particles fired at the range of 800 $\circ C$to 900 $\circ C$ were maintained as acicular particle shape, but there were mixed particles of acicular and round shape after fired at 950 $\circ C$. Ba-ferrite powder of the single phase was obtained in firing at 900~1000$\circ C$ and with 20 wt.% citric acid. There were unreacted phase of $\alpha-Fe_2O_3 \;and \; BaFe_2O_4$ phases as a second phase in case of sintering at below 850 $\circ C$. Acicular barium ferrite powder of single phase was also produced in firing at 900 $\circ C$ with 20 wt.% citric acid. The saturation magnetization of single phase of acicular $BaFe_12O_19$powder was about 51 emu/g and coercivity was about 4200 Oe.

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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 Korean Powder Metallurgy Institute
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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.

Compacting Press의 CNC화

  • Sano, Kazumi
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.6-8
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    • 1995
  • Among powder metallurgy products, complex shaped parts are difficult to be produced. Even i9f it shall be compacted until pet shape, the parts are easily apt to crack. thus it causes inferior productivity.It is present condition that net ahaped parts are obtained by adding after treatment. Clutch hub, pulley, representative partawifh upper 2 steps, tower 3 steps parts are corresponded to the above case. In recent years. muired parts are get to be thinner and thinner, and therefore extremely high compacting techniaues are required. Definition of most preferable com~actingp arts are I) Uniform density 2) Non crack and 3) Realization of net shape or near net shape productlon. For the above purpose, YOSHIZUKA baa developed n now oreas applying hydraulic servo control system.

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