• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.95-97
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• 2003

본 연구에서는 새도우마스크 제조공정에서 발생되는 Fe-Ni 계 폐산 용액에 Ni 성분을 용해시킨 복합 산용액을 원료용액으로 사용하여 분무열분해법에 의해 입도분포 및 조성이 균일하며, 입자형태가 구상이면서 평균입도가 100nm 이하인 Ni-ferrite 나노 분말을 제조하며 원료용액의 유입속도, nozzle tip 크기 및 공기압력의 반응조건 변화에 따른 생성분말의 특성 변화를 파악하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.47-53
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• 2003

자발착화연소법과 분무열분해법을 동시에 적용한 초음파분무연소법을 이용하여 40~50nm 크기를 갖는 결정성 ZnO 분말을 합성하였다. 또한 바리스터로의 응용을 위해 Bi, Sb, Co, Mn을 초기출발원료인 Zn-nitrate에 첨가하여 복합조성의 ZnO계 바리스터 분말을 합성하였다. 합성된 바리스터의 분말을 성형 및 소결하여 전기적 특성을 관찰한 결과 Co를 첨가한 분말보다 Mn을 첨가한 분말에서 우수한 전기적 특성을 나타내었다.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.58.1-58
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• 2003

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.172.2-172
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• 2003

• Journal of Powder Materials
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• v.9 no.4
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• pp.235-244
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• 2002

The effects of residual impurities on solid state sintering of the powder injection molded (PIMed) W-15wt%Cu nanocomposite powder were investigated. The W-Cu nanocomposite powder was produced by the mech-ano-chemical process consisting of high energy ball-milling and hydrogen reduction of W blue powder-cuO mixture. Solid state sintering of the powder compacts was conducted at $1050^{\circ}C$ for 2~10 h in hydrogen atmosphere. The den-sification of PIM specimen was slightly larger than that of PM(conventional PM specimen), being due to fast coalescence of aggregate in the PIM. The only difference between PIM and PM specimens was the amount of residual impurities. The carbon as a strong reduction agent effectively reduced residual W oxide in the PIM specimen. The $H_2O$ formed by $H_2$ reduction of oxide disintegrated W-Cu aggregates during removal process, on the contrary to this, micropore volume rapidly decreased due to coalescence of the disintegrated W-Cu aggregates during evolution of CO.It can be concluded that the higher densification was due to the earlier occurred Cu phase spreading that was induced by effective removal of residual oxides by carbon.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.103-103
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• 2003

대기나 물에 용해된 여러 가지 유해한 유기물을 분해하기 위한 방안으로서 다양한 광촉매 재료를 이용하려는 시도가 진행되고 있다. 하지만 광촉매 반응은, 현탁액 내에서 submicrometer 크기를 갖는 반도체재료에서 발생하므로 처리된 폐수로부터 촉매를 제거해야 하는 정제공정 (downstream process)이 필요하며, 이는 경제적인 측면에서 큰 경비를 요구하게 된다. 이를 해결 하기 위하여, 가장 우수한 광촉매 재료로 평가받는 TiO$_2$를 glass beads, sands, silica gel등의 물질에 고정시키거나, TiO$_2$를 자성 입자에 코팅시킨 형태인, 자성 광촉매입자를 응용하려는 연구가 최근 활발하게 진행되고 있다. 따라서 본 연구에서는 광촉매의 고정화와 재활용 효율을 향상시키기 위하여 TiO$_2$ 나노입자를 y-Fe$_2$O$_3$ 나노입자의 표면에 코팅하여 나노입자의 큰 비표면적을 활용하고 미세구조를 제어하여 입자간의 고정특성과 자기적 특성의 제어기술을 확립하고자 하였다.

• Composites Research
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• v.25 no.6
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• pp.178-185
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• 2012

One of a unique technique in manipulating a multifunctional composite is demonstrated in this study. An electric field is applied to a liquid suspension in order to align the inclusions along with the direction electric field. This is called FAiMTa(Field Aided Micro Tailoring). It makes orthotropic polymer composites by arranging the micro and/or nano size particle inclusions in chain-line formation. Several kinds of particles such as $Al_2O_3$, graphite, CNT(Carbon Nano Tube), W(Tungsten) are tested to verify the effectiveness of the FAiMTa. The particles redistributed in an epoxy suspension and their coupons show that mechanical and thermal properties of orthotropic and random composites containing those particles depend on the trend of particles' alignment. The micro-images of the functional composite from FAiMTa have been captures and their physical properties demonstrate their wide-range and state-of-the-art application for advanced multifunctional composites.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.320-323
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• 2001

일반적으로 고분자 재료는 그 자체로는 전기가 통하지 않는 전기절연체이나 여기에 카본블랙, 카본파이버, 금속분말 등 전도성을 가지는 입자들을 가지고 도핑할 경우 전기가 통하는 반도체 특성을 지니는 재료로 변화를 한다. 특히, 전기ㆍ전자재료 분야에서 이러한 특성을 이용한 재료 중 하나인 PTC 소자는 나노 크기를 가지는 카본 블랙과 고분자 재료의 복합화를 바탕으로 하여 과전류에 의한 발열의 감지 및 전류를 차단함으로서 회로를 보호하는 소자를 말하는 것으로서 현재 그 수요량이 급격히 증대하고 있는 기능성 재료중 하나이다. (중략)

• Composites Research
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• v.25 no.4
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• pp.93-97
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• 2012

Carbon nano fibers (CNFs) reinforced magnesium alloy (AZ91) matrix composites have been fabricated by liquid pressing process. In order to improve the dispersibility of CNFs and the wettability with magnesium alloy melt, CNFs were mixed with submicron sized SiC particles ($SiC_p$). Also, the mixture of CNFs and $SiC_p$ were coated with Ni by electroless plating. In liquid pressing process, AZ91 melts have been pressed hydrostatically and infiltrated into three reinforcement preforms of only CNFs, the mixture of CNFs and $SiC_p$ (CNF+$SiC_p$), and Ni coated CNFs and $SiC_p$ ((CNF+$SiC_p$)/Ni). Some CNFs agglomerates were observed in only CNFs reinforced composite. In cases of the composites reinforce with CNF+$SiC_p$ and (CNF+$SiC_p$)/Ni, CNFs were dispersed homogeneously in the matrix, which resulted in the improvement of mechanical properties. The compressive strengths of CNF+$SiC_p$ and (CNF+$SiC_p$)/Ni reinforced composites were 38% and 28% higher than that of only CNFs composite.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.245-250
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• 2019

We investigated the post-annealing effect of Sn-incorporated β-Ga₂O₃ (β-Ga₂O₃ : Sn) nanowires (NWs) grown on sapphire (0001) substrates using radio-frequency powder sputtering. The β-Ga₂O₃ : Sn NWs were converted to a porous structure during the vacuum annealing process at 800℃. Host non-stoichiometric Ga₂O_3-x, is transformed into stoichiometric Ga₂O₃, where Sn atoms separate and form Sn nano-clusters that gradually evaporate in a vacuum atmosphere. As a result, the amount of Sn atoms was reduced from 1.31 to 0.27 at%. Pores formed on the sides of β-Ga₂O₃ : Sn NWs were observed. This increases the ratio of the surface to the volume of β-Ga₂O₃ : Sn NWs.