• Title/Summary/Keyword: magnetic pulse compaction

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Fabrication and Properties of Densified Tungsten by Magnetic Pulse Compaction and Spark Plasma Sintering (자기펄스 성형 및 방전 플라즈마 소결 공정으로 제조한 텅스텐 소결체의 특성)

  • Lee, Eui Seon;Byun, Jongmin;Jeong, Young-Keun;Oh, Sung-Tag
    • Korean Journal of Materials Research
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    • v.30 no.6
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    • pp.321-325
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    • 2020
  • The present study demonstrates the effect of magnetic pulse compaction and spark plasma sintering on the microstructure and mechanical property of a sintered W body. The relative density of green specimens prepared by magnetic pulse compaction increases with increase in applied pressure, but when the applied pressure is 3.4 GPa or more, some cracks in the specimen are observed. The pressureless-sintered W shows neck growth between W particles, but there are still many pores. The sintered body fabricated by spark plasma sintering exhibits a relative density of above 90 %, and the specimen sintered at 1,600 ℃ after magnetic pulse compaction shows the highest density, with a relative density of 93.6 %. Compared to the specimen for which the W powder is directly sintered, the specimen sintered after magnetic pulse compaction shows a smaller crystal grain size, which is explained by the reduced W particle size and microstructure homogenization during the magnetic pulse compaction process. Sintering at 1,600 ℃ led to the largest Vickers hardness value, but the value is slightly lower than that of the conventional W sintered body, which is attributed mainly to the increased grain size and low sintering density.

The Effect of Pre-compaction on Density and Mechanical Properties of Magnetic Pulsed and Sintered $Al_2O_3$ Bulk

  • Hong, S.J.;Lee, J.K.;Lee, M.K.;Kim, W.W.;Rhee, C.K.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.967-968
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    • 2006
  • This research reports for the successful consolidation of $Al_2O_3$ powder with retained ultra-fine structure using MPC and sintering. Measurements in the consolidated $Al_2O_3$ bulk indicated that hardness, fracture toughenss, and breakdown voltage have been much improved relative to the conventional polycrystalline materials. Finally, optimization of the compaction parameters and sintering conditions will lead to the consolidation of $Al_2O_3$ nanopowder with higher density and even further enhanced mechanical properties.

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Fabrication and Dynamic Consolidation Behaviors of Rapidly Solidified Mg Alloy Powders (급속응고 Mg 합금분말의 제조 및 동적성형특성)

  • Chae, Hong-Jun;Kim, Young-Do;Kim, Taek-Soo
    • Journal of Powder Materials
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    • v.18 no.4
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    • pp.340-346
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    • 2011
  • In order to improve the weak mechanical properties of cast Mg alloys, Mg-$Zn_1Y_2$ (at%) alloy powders were synthesized using gas atomization, a typical rapid solidification process. The powders consist of fine dendrite structures less than 3 ${\mu}m$ in arm spacing. In order to fabricate a bulk form, the Mg powders were compacted using magnetic pulse compaction (MPC) under various processing parameters of pressure and temperature. The effects of the processing parameters on the microstructure and mechanical properties were systematically investigated.

The Static Thrust Calculation of a Hybrid Type Double-sided Linear Pulse Motor (Hybrid 형 양측식LPM의 정추력 계산)

  • 조윤현;이재봉
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.5
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    • pp.753-760
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    • 1994
  • This paper proposes a new method to compute the static thrust of a hybrid-type LPM by the coenergy method, which can be applied to a nonlinear programming of the optimization techniques for the optimal design. In the process of the computation, the magnetic nonlinearities of the permanent magnet, the primary and the secondary core are interpolated by the cubic spline method. And then, the equivalent magnetic circuit including the airgap reluctance which is a function of the displacement is modelled by the permeance method. The static thrust which is a derivative of the coenergy is computed by the Newton Raphson method at each displacement. To verify this proposed method, the results of the compjutation are compaction with those of the experiment obtained from the DLPM with 2 phase and 4 poles.

Milling Behaviors of Al-B4C Composite Powders Fabricated by Mechanical Milling Process (기계적 밀링 공정에 의해 제조된 Al-B4C 복합분말의 밀링 거동 연구)

  • Hong, Sung-Mo;Park, Jin-Ju;Park, Eun-Kwang;Lee, Min-Ku;Rhee, Chang-Kyu;Kim, Ju-Myoung;Lee, Jin-Kyu
    • Journal of Powder Materials
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    • v.19 no.4
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    • pp.291-296
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    • 2012
  • In the present work, Al-$B_4C$ composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of $B_4C$ sizes ( $100{\mu}m$, 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al-$B_4C$ composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller $B_4C$ particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm $B_4C$ added compact, it showed the highest values of compaction density and hardness compared with the conditions of $100{\mu}m$ and 500 nm additions, leading to the enhancement its mechanical properties.