• Title/Summary/Keyword: micro-powder

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Effect of Particle Size in Feedstock Properties in Micro Powder Injection Molding

  • Baek, Eung-Ryul;Supriadi, Sugeng;Choi, Chul-Jin;Lee, Byong-Taek;Lee, Jae-Wook
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.41-42
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    • 2006
  • Small powder size is very useful in achieving detailed structures. STS 316 nanopowders with an average diameter of 100 nm and $5{\mu}m$ were utilized to produce feedstock. The mixing behavior of the feedstock indicated that the nanoparticle feedstock produced the highest mixing torque at various powder loading compared to the micropowder feedstock. The nanoparticles feedstocks showed that elastic properties are dominant in flow behavior and high viscosity. Conversely the micropowders feedstocks, viscous properties are dominant in flow behavior and less viscosity, nanopowders feedstock perform lower flow activation energy than feedstock with bigger particles.

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Joint properties of carbon nanotube composite solder (탄소나노튜브 복합솔더의 본딩특성)

  • Ko, Young-Ki;Sa, Yoon-Ki;Choi, Yu-Ri;Lee, Chang-Woo;Yoo, Se-Hoon
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.74-74
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    • 2009
  • 카본나노튜브(CNT) 복합체는 우수한 기계적 성질을 가지고 있어 다양한 분야에서 연구되고 있다. 본 연구에서는 카본나노튜브(CNT)를 간단한 볼밀공정을 사용하여 Sn3.5Ag solder ball과 SAC305 powder 표면에 혼합하고 이를 통해 접합부 특성을 관찰하였다. 볼밀을 실시하기 전 카본나노튜브(CNT)는 초음파을 이용하여 분산을 실시하였다. Sn3.5Ag solder ball의 직경은 450um이고 SAC305 powder의 직경은 약 30um이었으며 이때 사용한 볼밀볼의 직경은 각각 3mm, 1mm이다. 볼밀 회전속도는 약 300rpm이고 6, 12, 18, 24시간동안 볼밀을 실시하였다. 24시간 볼밀 후에도 solder ball과 solder powder의 모양은 크게 변하지 않았다. SEM을 통해 표면을 관찰한 결과 분산된 카본나노튜브(CNT)는 solder ball과 solder powder의 표면에서 관찰되었다. 카본나노튜브(CNT)가 삽입된 solder ball은 BGA coupon 위에 놓고 Reflow를 실시하여 접합하였고 solder powder은 flux를 첨가하여 paste로 제조하여 2012 chip에 대한 접합특성을 관찰하였다. 카본나노튜브(CNT)는 solder ball 내부의 표면근처에서 관찰되었으며 카본나노튜브(CNT)가 혼합된 solder ball은 Aging 실시 후에 IMC 두께가 카본나노튜브(CNT)가 혼합되지 않은 solder ball에 비해 두께가 작고 접합강도는 약 10% 증가하였다. 또한 카본나노튜브(CNT)가 혼합된 solder paste와 카본나노튜브(CNT)가 혼합되지 않은 solder paste를 비교한 결과 인쇄성은 모두 양호하였으며 카본나노튜브(CNT)가 혼합된 paste를 사용한 chip의 전단강도가 높게 나타났다.

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Cold Compaction Behavior of Nano and Micro Aluminum Powder under High Pressure

  • Kim, Dasom;Park, Kwangjae;Kim, Kyungju;Cho, Seungchan;Hirayama, Yusuke;Takagi, Kenta;Kwon, Hansang
    • Composites Research
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    • v.32 no.3
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    • pp.141-147
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    • 2019
  • In this study, micro-sized and nano-sized pure aluminum (Al) powders were compressed by unidirectional pressure at room temperature. Although neither type of Al bulk was heated, they had a high relative density and improved mechanical properties. The microstructural analysis showed a difference in the process of densification according to particle size, and the mechanical properties were measured by the Vickers hardness test and the nano indentation test. The Vickers hardness of micro Al and nano Al fabricated in this study was five to eight times that of ordinary Al. The grain refinement effect was considered to be one of the strengthening factors, and the Hall-Petch equation was introduced to analyze the improved hardness caused by grain size reduction. In addition, the effect of particle size and dispersion of aluminum oxide in the bulk were additionally considered. Based on these results, the present study facilitates the examination of the effect of particle size on the mechanical properties of compacted bulk fabricated by the powder metallurgy method and suggests the possible way to improve the mechanical properties of nano-crystalline powders.

Post-buckling analysis of geometrically imperfect tapered curved micro-panels made of graphene oxide powder reinforced composite

  • Mirjavadi, Seyed Sajad;Forsat, Masoud;Barati, Mohammad Reza;Hamouda, AMS
    • Steel and Composite Structures
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    • v.36 no.1
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    • pp.63-74
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    • 2020
  • The present research investigates post-buckling behavior of geometrically imperfect tapered curved micro-panels made of graphene oxide powder (GOP) reinforced composite. Micro-scale effects on the panel structure have been included based on strain gradient elasticity. Micro-panel is considered to be tapered based on thickness variation along longitudinal direction. Weight fractions of uniformly and linearly distributed GOPs are included in material properties based on Halpin-Tsai homogenization scheme considering. Post-buckling curves have been determined based on both perfect and imperfect micro-panel assumptions. It is found that post-buckling curves are varying with the changes of GOPs weight fraction, geometric imperfection, GOP distribution type, variable thickness parameters, panel curvature radius and strain gradient.

Synthesis of GaN micro-scale powder and its characteristics (GaN 미세 분말의 합성과 특성)

  • 조성룡;여용운;이종원;박인용;김선태
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.554-557
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    • 2001
  • In this work, we had synthesis the GaN powder by direct reaction between Ga and NH$_3$at the temperature range of 1000∼1150$^{\circ}C$, and investigated the reaction condition dependence of the GaN yield and some properties of GaN powder. The synthesized powder had Platelet and prismatic shape and showed hexagonal crystalline structure with the lattice constants of a= 3.1895 ${\AA}$, c= 5.18394 ${\AA}$, and the ratio of c/a = 1.6253. The GaN powder synthesis processes were examined based on the oxidation process of mater, and found as combined with mass transport process for the initial stage and diffusion-limited reaction for the extended reaction.

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Micromachining of Pocket by Powder Blasting (Powder Blasting을 이용한 미세 포켓가공)

  • 박경호;최종순;김광현;박동삼
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.1060-1063
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    • 2001
  • The mechanical etching technique has recently been developed to a powder blasting technique for various materials, capable of producing micro structures larger than 100$\mu$m. This paper describes the performance of powder blasting technique in micro-pocketing of stainless steel and the effect of the number of nozzle scanning and the nozzle height on the depth and width of pockets. Experimental results showed that increasing the no. of nozzle scanning and decreasing the nozzle height resulted in the increase of depth and width in pockets. Increase of width results from wear of mask film.

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Fabrication of lab-on-a-chip on quartz glass using powder blasting (파우더 블라스팅을 이용한 Quartz Glass의 Lab-on-a-chip 성형)

  • Jang, Ho-su;Park, Dong-sam
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.8 no.4
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    • pp.14-19
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    • 2009
  • Micro fluid channels are machined on quartz glass using powder blasting, and the machining characteristics of the channels are experimentally evaluated. The powder blasting process parameters such as injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns affect machining results. In this study, the influence of the number of nozzle scanning, abrasive particle size, and blasting pressure on the formation of micro channels is investigated. Machined shapes and surface roughness are measured, and the results are discussed. Through the experiments and analysis, LOC are ettectinely machined on quartz glass using powder blasting.

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