• Title/Summary/Keyword: Magnetic pulsed compaction

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Nanostructures and Mechanical Properties of Copper Nano Powder Compacted by Magnetic Pulsed Compaction (MPC) Method (Magnetic Pulsed Compaction(MPC)법으로 성형된 Cu 나노 분말 성형체의 미세구조 및 기계적 특성)

  • 이근희;김민정;김경호;이창규;김흥회
    • Journal of Powder Materials
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    • v.9 no.2
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    • pp.124-132
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    • 2002
  • Nano Cu powders, synthesized by Pulsed Wire Evaporation (PWE) method, have been compacted by Magnetic Pulsed Cojpaction(MPC) method. The microstructure and mechanical properties were analyzed. The optimal condition for proper mechanical properties with nanostructure was found. Both pure nano Cu powders and passivated nano Cu powders were compacted, and the effect of passivated layer on the mechanical properties was investigated. The compacts by MPC, which had ultra-fine and uniform nanostructure, showed higher density of 95% of theoretical density than that of static compaction. The pur and passivated Cu compacted at $300^{\circ}C$ exhibited maximum hardnesses of 248 and 260 Hv, respectively. The wear resistance of those compacts corresponded to the hardness.

Magnetic Pulsed Compaction and Sintering Characteristics of Al Composite Powders Reinforced with Waste Stainless Steel Short Fibers (폐 스테인레스강 단섬유로 강화한 알루미늄 복합분말의 자기펄스압 성형 및 소결 특성)

  • Hyun, Chang-Yong;Won, Chul-Hyun;Park, Jae-Soon
    • Journal of Powder Materials
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    • v.14 no.6
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    • pp.380-385
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    • 2007
  • Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at $430^{\circ}C$ for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

Synthesis and Compaction of Al-based Nanopowders by Pulsed Discharge Method

  • Rhee, Chang-Kyu;Lee, Geun-Hee;Kim, Whung-Whoe
    • Journal of Powder Materials
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    • v.9 no.6
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    • pp.433-440
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    • 2002
  • Synthesis and compaction of Al-base nano powders by pulsed discharge method were investigated. The aluminum based powders with 50 to 200 nm of diameter were produced by pulsed wire evaporation method. The powders were covered with very thin oxide layer. The perspective process for the compaction and sintering of nanostructured metal-based materials stable in a wide temperature range can be seen in the densification of nano-sized metal powders with uniformly distributed hard ceramic particles. The promising approach lies in utilization of natural uniform mixtures of metal and ceramic phases, e.g. partially oxidized metal powders as fabricated in our synthesis method. Their particles consist of metal grains coated with oxide films. To construct a metal-matrix material from such powder, it is necessary to destroy the hard oxide coatings of particles during the compaction process. This goal was realized in our experiments with intensive magnetic pulsed compaction of aluminum nanopowders passivated in air.

Densification of Al2O3 Nanopowder by Magnetic Pulsed Compaction and Their Properties (자기펄스 가압성형법에 의한 알루미나 나노분말의 치밀화 및 특성 평가)

  • Kang, R.C.;Lee, M.K.;Kim, W.W.;Rhee, C.K.;Hong, S.J.
    • Journal of Powder Materials
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    • v.15 no.1
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    • pp.37-45
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    • 2008
  • This article presents the challenges toward the successful consolidation of $Al_2O_3$ nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured $Al_2O_3$ bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of $Al_2O_3$ bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated $Al_2O_3$ bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

Dynamic Compaction of Mechanochemically Alloyed Fe-Si Nano Powders by Magnetic Pulsed Pressure (기계화학적 합금화된 나노 Fe-6.5Si 분말의 자기 펄스압에 의한 동적성형)

  • Lee, G.-H.;Rhee, C.-K.;Kim, W.-W.;Yun, J.-W.;Lee, K.-S.
    • Journal of Powder Materials
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    • v.12 no.1
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    • pp.24-29
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    • 2005
  • Nano Fe-6.5wt%Si powders have been synthesized by mechano-chemical process (MCP) for an application of soft magnetic core. Owing to hard and brittle characteristics of Fe-6.5Si nano powders having large surface area, it is very difficult to reach high density more than 70% of theoretical density (~7.4 g/$cm_3$) by cold compaction. To overcome such problem a magnetic pulsed compaction (MPC), which is one of dynamic compaction techniques, was applied. The green density was achieved about 78% (~5.8 g/$cm_3$) by MPC at room temperature.

Magnetic Pulsed Compaction of nanostructured Al-Fe-Cr-Ti Powder and wear properties (Al-Fe-Cr-Ti 나노결정 합금분말의 자기펄스 성형 및 마모 특성)

  • Kim, Jun-Ho;Hong, Soon-Jik
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.528-530
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    • 2008
  • The effect of consolidation temperature on the microstructure, density and mechanical properties (especially, wear property) of $Al_{92.5}-Fe_{2.5}-Cr_{2.5}-Ti_{2.5}$ alloy fabricated by gas atomization and magnetic pulsed compaction was investigated. All consolidated alloys consisted of homogeneously distributed fine-grained fcc-Al matrix and intermetallic compounds. Relative higher mechanical properties in the MPCed specimen were attributed to the retention of the nanostructure in consolidated bulk without cracks. The as consolidated bulk by magnetic pulsed compaction showed the enhanced wear properties than that of a general consolidation process. In addition, the wear mechanism and fracture mode of MPCed bulk was discussed.

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Densification of TiO2 Nano Powder by Magnetic Pulsed Compaction (자기펄스 성형법에 의한 TiO2 나노 분말의 치밀화)

  • Kim, Hyo-Seob;Lee, Jeong-Goo;Rhee, Chang-Kyu;Koo, Jar-Myung;Hong, Soon-Jik
    • Korean Journal of Materials Research
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    • v.18 no.8
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    • pp.411-416
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    • 2008
  • In this research, fine-structure TiO2 bulks were fabricated in a combined application of magnetic pulsed compaction (MPC) and subsequent sintering and their densification behavior was investigated. The obtained density of $TiO_2$ bulk prepared via the combined processes increased as the MPC pressure increased from 0.3 to 0.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7 GPa was attributed to the decrease of the inter-particle distance of the pre-compacted component. High pressure and rapid compaction using magnetic pulsed compaction reduced the shrinkage rate (about 10% in this case) of the sintered bulks compared to general processing (about 20%). The mixing conditions of PVA, water, and $TiO_2$ nano powder for the compaction of $TiO_2$ nano powder did not affect the density and shrinkage of the sintered bulks due to the high pressure of the MPC.

Consolidation of Al-20wt%Si powder by Magnetic Pulsed Compaction (자기펄스 압축성형 장치를 이용한 Al-20wt%Si 분말성형)

  • Park, H.Y.;Kim, H.S.;Hong, S.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.459-461
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    • 2009
  • In this research, a new method for consolidation of Al-20wr%Si powders using a magnetic pulsed compaction (MPC) was introduced. A wide Range of experimental studies were carried out to characterize the mechanical properties and microstructure of the MPCed materials by means of SEM, TEM and tensile test. It was found that the effective properties like higher strength and full density were achieved while maintaining a fine microstructure. Consolidated bulk by MPC showed higher density without any crack than that of the general process. With increasing the number of MPC compaction, the density and mechanical properties were also greatly improved.

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Consolidation of Thermal Electric Material Powder by MPC Process and Thermal Electric Properties (MPC 공정에 의한 열전반도체 분말의 성형 및 열전특성)

  • Yun, J.S.;Koo, J.M.;Kim, T.S.;Hong, S.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.454-456
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    • 2009
  • N-Type $SbI_3$ doped $95%Bi_2Te_3+5%\;Bi_2Se_3$ compounds were newly fabricated by the combination of gas atomization process and Magnetic Pulsed Compaction process. The thermoelectric properties of the MPCed bulks according to consolidation temperatures were investigated by a combination of microscopy, XRD and thermoelectric property testing. The microstructure of MPCed bulk shows homogeneous and fine distribution through consolidated bulks due to the high solidification of compound powders. The research presented the challenges toward the successful consolidation of thermoelectric powder using magnetic pulsed compaction (MPC) and analysis of thermoelectric properties of the consolidated bulks.

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