• Applied Science and Convergence Technology
• /
• 제26권2호
• /
• pp.34-41
• /
• 2017

A 2.45 GHz microwave plasma with linear antenna has been prepared for hydrophobic and wear-resistible surface coating of carbon steel. Wear-resistible properties are required for the surface protection of cutting tools and achieved by depositing a hydrogenated amorphous carbon film on steel surface through linear microwave plasma source that has $TE_{10}-TEM$ waveguide. Compared to the existing RF plasma source driven by 13.56 MHz, linear microwave plasma source can easily generate high density plasma and provide faster deposition rate and wider process windows. In this study, $Ar/CH_4$ gas mixtures are used for hydrogenated amorphous carbon film deposition. When microwave power of 1000 W is applied, 40 cm long uniform $Ar/CH_4$ plasma could be obtained in gas pressure of 200~400 mTorr. The Vickers hardness measurement of hydrogenated amorphous carbon film on steel surface was evaluated. It was found the optimized deposition condition at $Ar:CH_4=25:25$ sccm, 300 mTorr with microwave power of 1000W and RF bias power of 100W. By deposition of hydrogenated amorphous carbon film, contact angle on steel surfaces increases from $43.9^{\circ}$ to $93.2^{\circ}$.

• 한국응용과학기술학회지
• /
• 제29권1호
• /
• pp.141-148
• /
• 2012

본 연구에서는 초소수성 실리카 에어로겔을 이용하여 단열 성능을 갖는 투명 필름용 유/무기 복합 코팅물질을 제조하였다. 바인더 물질로 사용된 자외선 경화형 우레탄 아크릴레이트 수지와 에어로겔과의 상용성을 위해 계면활성제(Brij 56)를 이용하여 에어로겔의 표면을 개질하였다. 개질된 에어로겔을 고분자 수지와 복합화한 코팅 용액을 폴리카보네이트 기지재에 코팅한 후 자외선경화를 통해 코팅필름을 제조하였다. 에어로겔이 10 vol% 함량으로 첨가되었을 때, 코팅필름의 단열성능은 측정된 열전도도 기준으로 순수 기지재 대비 28% 정도로 향상되었다. 또한, 코팅필름의 광투과율은 에어로겔이 50 vol%로 과량 첨가된 경우에도 80% 이상 높은 수준을 유지하였으며, 우수한 접착성(5B) 및 연필 경도(4H)를 보여주었다.

• 한국응용과학기술학회지
• /
• 제34권2호
• /
• pp.260-270
• /
• 2017

백색을 띄고 물리적 화학적으로 안정한 지르코니아는 열전도도가 낮고 강도와 인성, 내식성이 우수하여 단열재, 내화물과 같은 고온 재료와 각종 산업용 구조세라믹스에 사용되고 있다. 이러한 지르코니아를 낮은 경도 및 굴절률 등과 같은 단점을 가진 고분자 코팅제에 도입하게 되면 화학적, 전기적, 광학적인 특성이 향상된다. 이와 같이 유기 소재에 무기 소재를 혼합하여 사용하는 유-무기 하이브리드 코팅을 목적으로 본 연구에서는 지르코니아 표면에 trimethylchlorosilane(TMCS)과 hexamethyldisilazane(HMDZ)을 사용하여 실릴화반응을 통한 $-CH_3$기를 도입하여 소수성을 나노지르코니아 표면에 도입하였다. 소수화된 지르코니아 표면에서의 TMCS와 HMDZ에 의해 도입된 $Si-CH_3$의 존재는 FT-IR ATR spectroscopy를 통해 확인하였고, silicon 원소의 존재를 FE-SEM/EDS와 ICP-AES를 통해 확인하였다. 또한, 개질 전후의 지르코니아를 아크릴레이트 단량체에 분산하여 침강속도를 확인하여 분산성이 향상되는 것을 확인하였다. 지르코니아 입자의 크기 및 분포는 입도 분석기를 통해 확인하였으며, BET 분석을 통해 개질 반응 전후의 비표면적은 $18m^2/g$ 정도로 큰 변화가 없었다.

• 한국가시화정보학회지
• /
• 제9권4호
• /
• pp.41-46
• /
• 2011

Oxygen sensitive functional particles(OSParticle) were fabricated by three different methods for using the particles as oxygen sensors and PIV tracers. The used methods were a physical coating method, an ion-exchange method and a dispersion polymerization method. The physical coating method is dipping $SiO_2$ hollow particles into dye solution then drying. This method is very simple, but particles are not uniform in diameter and luminescence. The particles fabricated by the ion-exchange method have very uniform diameter and well doped. However, it can not be used in water since the particles are hydrophobic. In case of the dispersion polymerization method, the diameter of OSParticles is quite uniform. The diameter of OSParticles can be changed by controlling the quantity of AIBN (2,2'-azobis isobutyronitrile). For the purpose of dissolved oxygen concentration measurement in micro scale water flows, the dispersion polymerized OSParticles turn out to be the most superior functional particles. The luminescent intensity of OSParticles was tested with the variation of dissolved oxygen concentration in water samples. As a result, the luminescent intensity of OSParticles is monotonically decreased with increasing DO (Dissolved oxygen) concentration of water.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제14권3호
• /
• pp.110-117
• /
• 2006

Ice adhesion or cohesion leads to the decrease of the performance of ice making system, especially to dynamic type ice thermal storage system (DISS) which mainly forms ice from the flow of an aqueous solution. The ice adhesion is influenced by various parameters associated with operating or geometric condition. In this study, the influence on an adhesion of ice to the characteristic of cooling surface and to composition of an aqueous solution was fundamentally observed by using batch type cooling device,. a beaker. Three patterns of solution in each beaker were cooled with brine. Moreover, the characteristic of cooling surface on each beaker was distinguished to coating materials. Stirring power as a degree of the ice adhesion was measured. The stirring power to cooling heat transfer rate in each beaker was compared. As a result, the lowest stirring power of 8.9 W with non-adhesion of ice, was shown in the case of the aqueous solution of EG(4) + PG(1.5) + 1,6HD(1.5). in PE coating beaker.

• 공업화학
• /
• 제10권3호
• /
• pp.445-449
• /
• 1999

소수성인 poly[bis(trifluoroethoxy)phosphazene]에 methoxyethylenoxy 측쇄를 치환시켜 친수성을 증가시킨 포스파젠 고분자를 합성하였으며 합성된 고분자를 다공성 polypropylene 지지체위에 dip-coating법으로 금속이온 분리막을 제조하였다. $Cr^{3+},\;Co^{2+},\;Mn^{2-}$이온 수용액에 대한 분리실험을 $25^{\circ}C$에서 $60^{\circ}C$까지 온도범위에서 행하였다. 치환된 methoxyethylenoxy기 중의 ethylenoxy의 반복단위가 증가할수록 이온의 투과특성이 증가하는 것을 알수 있었다. Trifluoroethoxy methoxyethoxyethoxyethoxy co-substituted polyphosphazene의 경우 $Cr^{3-}$ 이온이 $60^{\circ}C$에서 분리계수 4.5의 값을 갖고 $Co^{2+},\;Mn^{2+}$ 이온들로부터 분리가 됨을 알 수 있었다.

• 반도체디스플레이기술학회지
• /
• 제16권1호
• /
• pp.106-111
• /
• 2017

When a substrate with a pixel-defining layer (bank) is coated, there arises capillary force due to surface tension and adhesive forces between a solvent and the bank layer. It brings in a degradation of film thickness and emission uniformities within pixels. With an attempt to suppress it, we have performed fluid flow simulations of capillary arise by varying the contact angle of bank and the bank structure. We have first demonstrated that the fluid flow model can reproduce the capillary phenomenon that was observed experimentally. It has been found that capillary arise can be suppressed using a hydrophobic material for the bank layer. Furthermore, it was suppressed by tilting the sidewalls outwardly (i.e., using a positive photoresistor). We can obtain very uniform films when the slope is $50^{\circ}$ with the contact angle of $40^{\circ}$.

• 한국분말재료학회지
• /
• 제19권3호
• /
• pp.177-181
• /
• 2012

Copper composite materials have attracted wide attention for energy applications. Especially $CuInS_2$ has a desirable direct band gap of 1.5 eV, which is well matched with the solar spectrum. $CuInS_2$ nanoparticles could make it possible to develop color-tunable $CuInS_2$ nanoparticle emitter in the near-infrared region (NIR) for energy application and bio imaging sensors. In this paper, $CuInS_2$ nanoparticles were successfully synthesized by thermo-decomposition methods. Surface modification of $CuInS_2$ nanoparticles were carried out with various semiconductor materials (CdS, ZnS) for enhanced optical properties. Surface modification and silica coating of hydrophobic nanoparticles could be dispersed in polar solvent for potential applications. Their optical properties were characterized by UV-vis spectroscopy and photoluminescence spectroscopy (PL). The structures of silica coated $CuInS_2$ were observed by transmission electron microscopy (TEM).

• 한국응용과학기술학회지
• /
• 제27권3호
• /
• pp.282-289
• /
• 2010

In preparation of silica aerogel-based hybrid coating materials, the combination of hydrophobic aerogel with organic polar binder material is shown to be very limited due to dissimilar surface property between two materials. Accordingly, the surface modification of the aerogel would be required to obtain compatibilized hybrid coating sols with homogeneous dispersion. In this study, the surface of silica aerogel particles was modified by using both surfactant adsorption and heat treatment methods. Four types of surfactants with different molecular weights and HLB values were used to examine the effect of chain length and hydrophilicity. The surface property of the modified aerogel was evaluated in terms of visible observation for aerogel dispersion in water, water contact angle measurement, and FT-IR analysis. In surface modification using surfactants, the effects of surfactant type and content, and mixing time as process parameter on the degree of hydrophilicity for the modified aerogel. In addition, the temperature condition in modification process via heat treatment was revealed to be significant factor to prepare aerogel with highly hydrophilic property.

• 한국표면공학회지
• /
• 제54권2호
• /
• pp.90-95
• /
• 2021

Surface modification technique enabling the control of condensation provides various benefit in various engineering systems, such as heat transfer, desalination, power plants, and so on. In this study, lubricant oil-impregnation into Teflon-coated nanoporous anodic oxide layer of aluminum to enhance a de-wetting and mobility of water droplet on surface. Due to the surface treatment improving water-repellency, the condensation mode is changed to dropwise, thus the frequency of sliding condensed water droplet on surface is increased. For these reasons, the surface of oil-impregnated Teflon-coated nanoporous anodic aluminum oxide shows significantly enhanced condensation heat transfer compared to bare aluminum surface. In addition, the porosity of anodic aluminum oxide affected the mobility of water droplet even with oil-impregnation and Teflon-coating, indicating that the optimization of porous structure of anodic oxide is required for maximizing the condensation heat transfer.