• Korean Journal of Materials Research
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• v.18 no.7
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• pp.389-393
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• 2008

Nano-sized $TiO_2$-60 wt% SrO composite powders were synthesized by a sol-gel method using titanium isopropoxide and $Sr(OH)_2\;{\cdot}\;8H_2O$ as precursors. 3, -5, -7 wt%Ag spot-coated $TiO_2$-60 wt% SrO composite powders were synthesized by a Ag electroless deposition method using $TiO_2$-60 wt% SrO composite powders calcined at $1050^{\circ}C$, which mainly exhibited the $SrTiO_3$phase. However, a small number of rutile $TiO_2$, $Sr_2TiO_4$ and $SrO_2$ phases were also detected. In the Ag spot-coated powders synthesized by electroless deposition, nano-sized particles about 5-25 nm in diameter adhered to the $TiO_2$-60 wt% SrO composite powders. The photocatalytic activity of Ag spot-coated $TiO_2$-SrO and $TiO_2$-SrO composite powders for degradation of phenol showed that all of $TiO_2$-SrO composite powders were highly active under UV light irradiation. 7 wt%Ag spot-coated $TiO_2$-60wt.%SrO composite powders had a relatively higher photocatalytic activity than did $TiO_2$-SrO composite powders under visible light.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.87-90
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• 2005

This paper presents an evaluation of the effect of titanium dioxide nanoparticles in sulfonated poly(ether ether ketone) (SPEEK) with sulfonation degree of 57%. A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxide nanoparticles content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of morphology, membranes are homogeneous and exhibit a good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with standard nafion membrane.

• 연구논문집
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• s.23
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• pp.165-171
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• 1993

$Si_3N_4/Sic$. nano-composites were fabricated by hot-pressing, gas pressure sintering. The composites contained up to 50 wt. % of SiC. The mechanical properties such as strength, toughness, and hardness of the composite are compared each other. The flexural strength of the composites was improved significantly by introducing fine SiC particles into $Si_3N_4$ matrix, while the fracture toughness was not improved. The increase in flexural strength is attributed to the formation of uniformly elongated $\beta -Si_3N_4$ grains as well as the reduction of grain size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.189-192
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• 2004

To improvement life-time of the organic light emitting diodes(OLEDs). We investigate the inorganic composite film based on MgO and $SiO_2$ to protect from the moisture and oxygen. The inorganic composite films are added the base materials to the co-operate materials using the mixed process and it is deposited on plastic substrate by e-beam evaporator. In order to analyze as kinds of inorganic materials, Water Vapor method of Transmission Rate (WVTR) and Oxygen Transmission Rate (OTR) are measured by Permatran equipment(MOCON Corp.). For comparison. an MgD- and $SiO_2$-based composite film has lower values of WVTR and OTR than inorganic composite/compound films of ones. The results obtained here shows that this film is suitable for passivation layer to extend the life-time of OLEDs.

• Current Optics and Photonics
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• v.3 no.1
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• pp.66-71
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• 2019

Application of liquid crystal (LC) materials to a flexible device is challenging because the bending of LC displays easily causes change in thickness of the LC layer and orientation of LCs, resulting in deterioration in a displayed image quality. In this work, we demonstrate a prototype device combining a flexible polymer substrate and an optically isotropic LC-polymer composite in which the device consists of interdigitated in-plane switching electrodes deposited on a flexible colorless polyimide substrate and the composite consisting of nano-sized LC droplets in a polymer matrix. The device can keep good electro-optic characteristics even when it is in a bending state because the LC orientation is not disturbed in both voltage-off and -on states. The proposed device shows a high potential to be applicable for future flexible LC devices.

• Transactions on Electrical and Electronic Materials
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• v.15 no.4
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• pp.193-197
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• 2014

Si-carbon composites as anode materials for lithium rechargeable batteries were prepared simply by mixing Si nanoparticles with carbon black and/or graphite through a solution process. Si nanoparticles were well dispersed and deposited on the surface of the carbon in a tetrahydrofuran solution. Si-carbon composites showed more than 700 mAh/g of initial capacity under less than 20% loading of Si nanoparticle in the composites. While the electrode with only Si nanoparticles showed fast capacity fading during continuous cycling, Si-carbon composite electrodes showed higher capacities. The cycle performances of Si nanoparticles in composites containing graphite were improved due to the role of the graphite as a matrix.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.330-331
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• 2006

Fabrication of a nano-laminar ceramic composite by sintering thin ceramic plates was examined. Silver-coated glass flakes with a thickness of less than $1{\mu}m$ were consolidated by pulsed current sintering or hotpressing to obtain model composites. The samples sintered at the optimum conditions were fairly dense, and the flakes were aligned by uniaxial press. The metal coating remained on the flakes through the sintering process, and became an interface layer between the flakes. No crack propagation through the transverse direction of the lamellar was observed in the indentation test. The possibilities of high resistance against crack propagation was suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.210-211
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• 2006

This study presents the technology and application of hybrid insulation film for electric magnet wire. In order to make the high efficient motor with high space factor, it is necessary to develop a self-lubrication heat-resistant insulation film that can be used when the space factor 70% or more. A key to achieving high windability is to increase the lubricity and bonding strength of vanish, which for a magnet wire generally determines the mechanical scratches characteristics. Effective ways to reduce scratches include improving insulation film prepared by organic and inorganic hybrid synthesis methods.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.642-643
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• 2006

Direct reduction and carburization process was thought one of the best methods to make nano-sized WC powder. The oxide powders were mixed with graphite powder by ball milling in the compositions of WC-5,-10wt%Co. The mixture was heated at the temperatures of $600{\sim}800^{\circ}C$ for 5 hours in Ar. The reaction time of the reduction and carburization was decreased as heating temperatures and cobalt content increased. The mean size of WC/Co composite powders was about 260 nm after the reactions. And the mean size of WC grains in WC/Co composite powders was about 38 nm after the reaction at $800^{\circ}C$ for 5 hours.

• Nano
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• v.13 no.12
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• pp.1850144.1-1850144.13
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• 2018

A nano-$MoS_2$/montmorillonite K-10 (K10) composite was prepared and characterized. The composite contains two types of 2H-$MoS_2$ nanoparticles. One is the hollow spherical $MoS_2$ with a size range of 75 nm, and the other is the spherical nano cluster of $MoS_2$ with a size range of 30 nm. The two kinds of nano-$MoS_2$ were formed via assembly of numerous $MoS_2$ nano-platelets with a size of ~10 nm. A tribological comparison was then made among nano-$MoS_2$/K10, K10, nano-$MoS_2$ and a mechanical mixture of K10 and nano-$MoS_2$. K10 reduced the wear but slightly increased the friction. Nano-$MoS_2$ remarkably reduced both friction and wear. The mechanical mixture demonstrated better wear resistance than nano-$MoS_2$, indicating a synergistic anti-wear effect of nano-$MoS_2$ and K10. The synergistic effect was reinforced using nano-$MoS_2$/K10 instead of the mechanical mixture. A part of the $MoS_2$ in the contact region always lubricated the friction pair, and the rest formed a tribofilm. K10 segregated the friction pair to alleviate the ablation wear but magnified the abrasive wear. S-$MoS_2$ protects K10 and they together function as both a lubricant and an isolating agent to reduce the ablation and abrasive wear.