• 제목/요약/키워드: Metal Powders

검색결과 577건 처리시간 0.034초

플라즈마분체 오버레이법에 의한 알루미늄합금 표면의 경화특성에 관한 연구( II ) -후막 표면 합금화층의 경화특성과 내마모성- (Hardening Characteristics of Aluminum Alloy Surface by PTA Overlaying with Metal Powders (II) -Hardening charactersteristics and wear resistance of thicker surface alloyed layer-)

  • 이규천;;강원석;이영호
    • Journal of Welding and Joining
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    • 제12권4호
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    • pp.102-109
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    • 1994
  • The thick and hard alloyed layer was formed on the surface of Aluminum Cast Alloy(AC2B) by PTA overlaying process with Cr, Cu and Ni metal powders under the condition of overlaying current 150A, overlaying speed 150mm/min and different powder feeding rate 5-20g/min. The characteristics of hardening and were resistance of alloyed layer have been investigated in relation to microstructure of alloyed layer. As a result, it was made clear that Cu powder was the most superier one in three metal powders used due to an uniform hardness distribution of Hv 250-350, good wear resistance and freedom from cracking in alloyed layer of which microstructure consisted of hypereutectic. On the contrary, irregular hardness distribution was usually obtained in Cr or Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv 400-850 at about 60wt% Cr or 40wt% Ni in alloyed layer. However the cracking occurred in these alloyed layers with higher hardness than Hv 250-300 at more than 20-25wt% of Cr or Ni contents in alloyed layer. Wear rate of alloyed layer was decreased to 1/10 in Cu alloyed layer and 1/5 or 1/3 in Cr or Ni alloyed layer with same hardness of about Hv 300 in comparison with that of base metal at higher sliding speed.

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Characteristics of Nano-dispersed Powder by Electric Explosion of Conductors

  • Kwon, Young-Soon;Kim, Ji-Soon;Moon, Jin-Soo;Kim, Hwan-Tae;Ilyin, Alexander-P;Rhee, Chang-Kyu;Rim, Geun-Hie
    • 한국분말재료학회지
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    • 제10권6호
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    • pp.430-435
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    • 2003
  • The phenomenon of electrical explosion of conductors is considered in the context of the changes in the energy and structural states of the metal at the stages of energy delivery and relaxation of the primary products of EEC. It is shown that these changes are related to the forced interaction of an intense energy flux with matter and to the subsequent spontaneous relaxation processes. The characteristics of nano-sized metal powders are also discussed. The preferential gas media during EEC is Ar+$H_2$. An increase in $e/e_s$ (in the range of values studied) leads to a reduction in the metal content. For reactive powders obtained with high metal content, it is necessary to separate the SFAP fractions, which settled on the negative electrode of the electric filter.

금속분말의 레이저 공정 기술 (Laser Processing Technology using Metal Powders)

  • 장정환;문영훈
    • 대한금속재료학회지
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    • 제50권3호
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    • pp.191-200
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    • 2012
  • The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.