• 한국분말재료학회지
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• 제10권3호
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• pp.151-156
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• 2003

In the present work some properties of nanopowders and possible areas of their applications are discussed. Main attention is paid to the use of nanodispersed powders (NDP) in new materials production technologies.

• 한국분말재료학회지
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• 제23권6호
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• pp.409-413
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• 2016

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

• Korean Chemical Engineering Research
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• 제57권6호
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• pp.790-803
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• 2019

디옥틸테레프탈산(DOTP) 제조공정은 분말형태의 테레프탈산(PTA) 주원료와 옥탄올(Octanol)의 에스테르화 반응을 통해 플라스틱 가소제를 생산하는 공정이다. 본 연구에서는 이 공정의 반응기 내에 가연성 용제나 유증기가 존재하고 있는 상태에서 분말형태로 맨홀에 직접 투입하는 테레프탈산의 분진폭발 특성에 관하여 고찰하였다. 분진의 입경과 입도분포 분진특성 실험을 하였고, 화재 폭발특성과 발화온도를 추정하기 위한 분진의 열분해 특성을 조사하였다. 또한 폭발민감도를 평가하기 위한 최소점화에너지 실험을 실시하였다. 실험결과 테레프탈산의 분체 특성은 평균입경이 $143.433{\mu}m$으로 나타났다. 이러한 입경과 입도분포 조건에서 실시한 열분석으로부터 분진의 발화온도는 약 $253^{\circ}C$로 나타났다. 테레프탈산의 폭발민감도를 알기 위해 조사한 폭발하한 농도(LEL)는 $50g/m^3$으로 측정되었다. 폭발민감도를 나타내는 최소점화에너지(MIE)는 (10 < MIE < 300) mJ로 나타났으며, 점화 확률에 기반하여 추산한 최소점화에너지 추정값(Es)은 210 mJ로서 충분한 점화원이 있는 경우 폭발할 수 있음을 알 수 있었다. 또한 폭발피해 예측에 필요한 폭발강도 특성을 조사한 결과, 테레프탈산 분진의 최대폭발압력($P_{max}$), 최대폭발압력상승속도[$({\frac{dP}{dt}})_{max}$]는 각각 7.1 bar, 511 bar/s로 나타났다. 분진폭발지수(Kst)는 139 mbar/s로 분진폭발등급 St 1에 해당되는 것으로 나타났다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.27-32
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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.

• 한국분말재료학회지
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• 제19권1호
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• pp.49-54
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• 2012

Tungsten nanopowders were produced by the method of wires electrical explosion in the different gases. The study of phase and dispersed composition of the powders was carried out. The influence of electrical parameters such as the value of energy input in wire and the arc stage of the explosion was discussed. The factors that make for decreasing the particles size are the lower pressure of surrounding gas and the use of addition of chemically reactive gas.

• 한국분말재료학회지
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• 제19권1호
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• pp.40-48
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• 2012

The current situation of the nanopowders production technology based on the process of electrical explosion of wires is described. The advantages and disadvantages of the electroexplosive technology are indicated. The results of studies characterizing the effect of the electrical explosion conditions on the nanopowders properties are presented, including latest results: conditions of nanopowders passivation, conditions of nanopowders production having narrow size distribution, the methods of nanopowders diagnostic and standartization. In addition, the application and area of future research on this technology are proposed.

• 한국전기전자재료학회논문지
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• 제29권12호
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• pp.786-790
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• 2016

Hole explosion behaviors were observed during drilling fine holes with laser beam on the LTCC green bar of $320{\mu}m$ thick after lamination of green sheets prepared by tape casting of thick film process. The incidence of these hole explosions was inversely proportional to hole sizes. The incidence of hole explosion was 20 % number of hole with the size of $60{\mu}m$ exploded for the UV radiation, while the explosion did not appear for hole sizes over $100{\mu}m$. To prevent hole explosion behavior during laser-drilling of fine holes, carbon black powder was added as an additive in the LTCC composition, which has superior thermal durability. As a consequence, hole explosion rate was suppressed to 0.8 % for the hole size of $50{\mu}m$ green sheet with the carbon black amount of 10 weight % and the laser power of 3 watt. Added carbon is thought to reduce the heat-affected region during laser drilling.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2004년도 International Symposium on Powder Materials and Processing
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• pp.63-64
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• 2004

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.165-165
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• 2008

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.504-511
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• 2011

Nano-sized Sn powder was prepared by pulsed wire evaporation method. The Sn powder and carbon black were charged in jar and ball milled. The milling time was varied with 10 min., 1h, 2h, and 4h, respectively. The milled powders were dried and the shape and size were observed by FE-SEM. Nano-sized Sn powders were plastic-deformed and agglomerated by impact force of balls and heat generated during the SPEX milling. The agglomerated Sn powder also consisted of many nano-sized particles. Initial discharge capacities of milled Sn electrode powders with carbon powder were milled for 10 min., 1h, 2h, and 4h were 787, 829, 827, and 816 mAh/g, respectively. After 5 cycle, discharge capacities of Sn electrode powders with carbon powder milled for 10 min., 1h, 2h, and 4h decreased as 271, 331, 351, and 287 mAh/g, respectively. Because Sn electrode powders milled for 2h constist of uniform and fine size, the cyclability of coin cell made of this powders is better than others.