• 한국입자에어로졸학회지
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• 제6권1호
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• pp.37-46
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• 2010

Cu nano-colloid was prepared by wire electric explosion process under de-mineralized water and anhydrous ethanol. To control the properties of Cu nano-colloid, experimental conditions such as diameter of Cu wire and applied voltage were changed. The optimal Cu nano-colloid was prepared when the 0.1mm diameter of Cu wire with the applied voltage of 2000 V was used. The shape of Cu particles in colloid was spherical and the XRD result revealed that the phase of Cu particles was cubic phase. About 20nm Cu nanoparticles with high crystallinity were successfully prepared using wire explosion process under anhydrous ethanol and they showed more than 100 hours dispersion stability.

• 대한기계학회논문집A
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• 제31권9호
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• pp.910-914
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• 2007

We present a simple and an inexpensive method for the fabrication of a nano-fluidic filter and a nano-pore micromixer using self-assembly of nano-spheres and surface tension. Colloid-plug was formed by surface tension of liquid in a microchannel to fabricate nanofluidic filter. When colloid is evaporated, nano-spheres in a colloid are orderly stacked by a capillary force. Orderly stacked nano-spheres form 3-D nano-mesh which can be used as a mesh structure of a fluidic filter. We used silica nano-sphere whose diameter is $567{\pm}85nm$, and silicon micro-channel of $50{\mu}m$-diameter. Fabricated nano-fluidic filter in a micro-channel has median pore diameter of 158nm which was in agreement with expected diameter of the nano-pore of $128{\pm}19nm$. A nano-pore micromixer consists of $200\;{\mu}m-wide,\;100\;{\mu}m-deep$ micro-channel and self-assembled nano-spheres. In the nano-pore micromixer, two different fluids had no sooner met together than two fluids begin to mix at wide region. From the experimental study, we completely apply self-assembly of nano-spheres to nano-fluidic devices.

• 한국세라믹학회지
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• 제49권1호
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• pp.78-83
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• 2012

The electrophoretic deposition(EPD) of ZnO nano-sized colloids is investigated by changing the colloid number concentration, applied force, and deposition time. The change of the colloid size in a suspension was examined by the different colloid number concentrations (N = $3.98{\times}10^{15}$, N = $3.98{\times}10^{14}$, and N = $3.98{\times}10^{13}$) with an increase of the deposition time and applied forces. Deposition behavior was investigated by changing the applied fields (from DC 5 V to 50 V) and the deposition time (5 min to 25 min). The surface microstructures of the as-deposited films were investigated by SEM. The dried films were sintered from $850^{\circ}C$ to $1,050^{\circ}C$ for 2 h and then the microstructures were also explored by SEM. The agglomeration rate was enhanced by increasing the colloid number concentration of colloids. Colloid number concentration in a suspension must be rapidly decreased at higher values of the electric field. ZnO nano-sized colloids had the highest zeta potential value of over -28 mV in methanol. A homogeneous microstructure was obtained at colloid number concentration of N = $3.98{\times}10^{13}$, applied DC field of 5 V/cm and 15 min of deposition time at an electrode distance of 1.5 cm. Under these conditions, the deposited films were sintered at $850^{\circ}C$ and $1,050^{\circ}C$ for 2 h. The results show a typical pore-free surface morphology of a uniform thickness of 400 nm under these experimental conditions.

• 한국분말재료학회지
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• 제19권6호
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• pp.424-428
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• 2012

Nano Pd spot-coated active carbon powders were synthesized by a hydrothermal-attachment method (HAA) using PVP capped Pd colloid in a high pressure bomb at $250^{\circ}C$, 450 psi, respectively. The PVP capped Pd colloid was synthesized by the precipitation-redispersion method. PVP capped Pd nano particles showed the narrow size distribution and their particle sizes were less than 8nm in diameter. In the case of nano Pd-spot coated active carbon powders, nano-sized Pd particles were adhered in the active carbon powder surface by HAA method. The component of Pd was homogeneously distributed on the active carbon surface.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.175-178
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• 2007

The mode transition from cone-jet to dripping in colloid thruster operation has been analytically investigated. The transition has been predicted by the dynamic behavior of a liquid drop at the tip of the cone-jet. Conservation laws are applied to determine the upward motion of the drop, and an instability model of electrified jets is used to determine the jet breakup. Finally, for the first time, the analysis enables prediction of the transition in terms of the Weber number and electric Bond number. The predictions are in good agreement with experimental data.

• 대한기계학회논문집A
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• 제38권10호
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• pp.1117-1123
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• 2014

본 연구는 균열 치유 물질로 알려진 $SiO_2$ 나노 콜로이드의 첨가량을 달리한 $Si_3N_4$를 소결하여, 경면 연마한 시험편 표면에 $SiO_2$ 나노 콜로이드를 코팅하여 1273 K, 공기중에서 1시간 균열치유 처리하였다. 그 후, 마모시험편은 1073, 1273 및 1573 K에서 10분간 열처리하여 시험을 실시하였다. $SiO_2$ 나노 콜로이드를 코팅하여 열처리한 표면은 무코팅 표면보다 약간 거칠게 나타났으며, 열처리 온도에 따라 표면의 산화 정도는 조도와 뚜렷한 상관관계는 가지지 않았다. 그리고 마찰계수, 마모손실 및 굽힘강도는 표면 거칠기와 관계가 없었다. SKD11 상대재에 대하여 연삭마모의 거동을 보였으며, 마찰계수와 마모손실은 비례하였다. 또한, 강도가 클수록 마찰계수가 작고, 마모손실도 작았다. $SiO_2$ 나노 콜로이드 량의 증가에 따라서 마찰계수는 증가하다가 일정하게 되었지만, 마모손실은 증가하였다. 또한 열처리 온도가 증가함에 따라서 마찰계수는 약간 증가하는 경향을 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2193-2194
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• 2007

• 한국세라믹학회지
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• 제46권3호
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• pp.288-294
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• 2009

The platelet AlO(OH) nano colloids were prepared by hydrothermal reaction of the $\gamma-Al_2O_3$ obtained with dehydration of $\gamma$-AlO(OH) and dilute $CH_3COOH$ solution. In hydrothermal reaction process, reversible reaction was accompanied between $\gamma-Al_2O_3$ and AlO(OH), and hydrothermal reaction temperature, hydrothermal reaction time and $CH_3COOH$ concentration had an effect on the crystal structure, surface chemical property, surface area, pore characteristics and crystal morphology of the AlO(OH) nano colloid particles. In this study, it was investigated to the hydrothermal reaction condition of the AlO(OH) nano colloid for using catalyst support, heat resisting agent, adsorbents, binder, polishing agent and coating agent. The crystal structure, surface area, pore volume and pore size of the platelet AlO(OH) nano colloids were investigated by XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method in liquid nitrogen temperature.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.826-829
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• 2004

An increasing interest in fire safety engineering can currently be identified in Korea and overseas. The fire-resistant characteristics of spray coating material for fire protection with or without nano $Al(OH)_3$ colloid has been experimentally investigated and the results are presented in this paper. The fire-resistance characteristics of spray coating material with nano $Al(OH)_3$ were superior to those without $Al(OH)_3$. Especially, spray coating material with nano material showed that thermal characteristic in the early days was remarkably excellent.

• 한국재료학회지
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• 제12권4호
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• pp.264-268
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• 2002

Magnetic fluid is a very stable colloid that is attracted by magnetic force as wholly. The magnetic fluids is composed with 10 nm magnetic materials such as magnetite, iron etc., which is dispersed homogeneously in solvent by coating surfactant on their surface. Also this colloid is not separated into magnetic particles and solvent even under magnetic field, centrifugal force, gravity. Due to these properties, the magnetic fluids is used in high vacuum seal, exclusion seal, damper, etc. I would like to introduce the specific properties and applications of the magnetic fluids.