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Manufacturing and Evaluation of the Properties of Hybrid Bulk Material by Shock-compaction of Nanocrystalline Cu-Ni Mixed Powder

나노 구리-니켈 혼합분말의 충격압축법을 통한 복합벌크재의 제조 및 특성평가

  • Kim, Wooyeol (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Ahn, Dong-Hyun (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Park, Lee Ju (4th Agenda Research Division, Agency for Defense Development) ;
  • Kim, Hyoung Seop (Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH))
  • 김우열 (포항공과대학교 신소재공학과) ;
  • 안동현 (포항공과대학교 신소재공학과) ;
  • 박이주 (국방과학연구소 4기술연구본부 2부) ;
  • 김형섭 (포항공과대학교 신소재공학과)
  • Received : 2014.06.03
  • Accepted : 2014.06.19
  • Published : 2014.06.28

Abstract

In this study, nanocrystalline Cu-Ni bulk materials with various compositions were cold compacted by a shock compaction method using a single-stage gas gun system. Since the oxide layers on powder surface disturbs bonding between powder particles during the shock compaction process, each nanopowder was hydrogen-reduced to remove the oxide layers. X-ray peak analysis shows that hydrogen reduction successfully removed the oxide layers from the nano powders. For the shock compaction process, mixed powder samples with various compositions were prepared using a roller mixer. After the shock compaction process, the density of specimens increased up to 95% of the relative density. Longitudinal cross-sections of the shock compacted specimen demonstrates that a boundary between two powders are clearly distinguished and agglomerated powder particles remained in the compacted bulk. Internal crack tended to decrease with an increase in volumetric ratio of nano Cu powders in compacted bulk, showing that nano Cu powders has a higher coherency than nano Ni powders. On the other hand, hardness results are dominated by volume fraction of the nano Ni powder. The crystalline size of the shock compacted bulk materials was greatly reduced from the initial powder crystalline size since the shock wave severely deformed the powders.

Keywords

References

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