• Journal of Welding and Joining
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• 제16권2호
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• pp.122-128
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• 1998

This investigation was performed to collect fundamental informations concerning the behavior of glass solders on ceramic joining process. The wettability of glasses on two types of alumina was evaluated by sessile drop method. SiO$_2$-CaO-Al$_2$O$_3$system glasses were selected as solder glasses, and alumina that have different purities were used for substrate materials. It is indicated that contact angles of glasses on 99% purity of alumina substrate do not change as increasing time at elevated temperature, however the contact angles on the 92% purity of alumina substrate exhibit the strong time dependency. The time-dependent property on 92% alumina was due to the interlayer reactions occurred between the glass solder and impurities on the substrate.

• Nuclear Engineering and Technology
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• 제43권3호
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• pp.205-216
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• 2011

Recently, many research studies have investigated the enormous critical heat flux (CHF) enhancement caused by nanofluids during pool boiling and flow boiling. One of the main reasons for this enhancement is nanoparticle deposition on the heated surface. However, in real applications, nanofluids create many problems when used as working fluids because of sedimentation and aggregation. Therefore, artificial surfaces on silicon and metal have been developed to create an effect similar to that of nanoparticle deposition. These modified surfaces have proved capable of greatly increasing the CHF during pool boiling, and good results have also been observed during flow boiling. In this study, we demonstrate that the wetting ability of a surface, i.e., wettability, and the liquid spreading ability (hydrophilic surface property), are key parameters for increasing the CHF during both pool and flow boiling. We also demonstrate that when the fuel surface in nuclear power plants is modified in a similar manner, it has the same effect, producing a large CHF enhancement.

• 멤브레인
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• 제7권3호
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• pp.123-130
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• 1997

휴대용 정보 통신기기의 소형 경량화에 적합한 고용량 전지인 리튬이온 이차전지에 응용되는 미세다공성 고분자 격리막에 관한 특성을 검토하였다. 격리막으로서 요구되어지는 항목은 전지 성능에도 관련되며, 안전에도 관련된 것들 이어서, 전지의 부재로서 상당히 중요한 부분을 차지하고 있다. 철재는 폴리에틸렌(PE) 등과 같은 폴리올레핀 소재를 연신하여 제조한 미세다공성 격리막이 주로 채용되고 있으며, 다양한 shut-down온도에 적용 가능하고, wettability가 향상된 미세다공성 격리막으로서, 불소계 고분자의 적용 및 폴리올레핀계 소재의 표면개질 등에 관한 연구가 지속되고 있다.

• 폴리머
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• 제28권3호
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• pp.218-224
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• 2004

고분자 생체재료에서 세포부착과 성장은 재료의 적심성, 화학구조, 표면전하 및 거칠기 등의 표면 성질에 의존한다. 본 연구에서는 저밀도 폴리에틸렌 필름 (LDPE)의 표면 적심성과 골수유래 줄기세포의 증식 및 성장성을 측정하기 위하여 플라즈마 처리를 실시하였으며 개질된 필름 표면의 특성을 조사하였다. 또한 LDPE 필름에서의 세포부착과 증식률은 세포수 관찰과 역전사 중합효소 연쇄반응으로 확인하였다. 표면성질의 하나인 물 접촉각 측정 결과 플라즈마 처리 시간이 길어짐에 따라 필름표면의 접촉각이 감소하였으며 암형성 유전자와 암억제 유전자의 발현률이 60∼70$^{\circ}$ 사이에서 높음을 확인할 수 있었다. 또한 세포수 관찰을 통해 접촉각이 60∼70$^{\circ}$인 표면에서 세포 증식률이 우수하여 표면성질이 세포의 성장과 분화에 중요함을 확인하였다.

• 접착 및 계면
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• 제12권1호
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• pp.26-33
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• 2011

폴리케톤 필름의 산처리 조건에 따른 필름 표면의 화학적인 변화를 접촉각과 XPS를 이용하여 분석하고, 모폴로지의 변화를 SEM과 AFM을 통하여 살펴보고, 최종적으로 이러한 변화가 폴리케톤 필름과 고무와의 계면접착력에 어떠한 영향을 미치는지를 살펴보았다. 인산처리에 의하여 폴리케톤 필름의 표면에 젖음성이 증가하여 인산의 농도 및 처리시간에 따라서 접촉각이 감소하였으며, 표면에 산소함유기들이 증가하는 결과를 보였다. 인산농도와 처리시간이 증가함에 따라 표면에 crack과 etching이 증가하여 표면거칠기가 증가하였으나, 산처리 조건이 강화되면서 폴리케톤 필름의 표면에 degradation이 발생하여 roughness가 감소하는 결과를 보였다. 폴리케톤과 고무와의 계면접착력을 살펴본 결과, pH 0.74에서 120 min, pH 0.4에서 60 min 처리한 경우에 최대 계면접착력을 보였으며, 산처리 조건이 그 이상으로 증가하면서 degradation이 발생하면서 계면접착력이 감소하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.458-458
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• 2012

Fuel Cell is used stacking metal or polymer substrate. This hydro property of substrate surface is very important. Usually, surface property is hydrophilic. The surface oxidation of SUS is investigated through plasma treatments with an atmospheric-pressure dielectric barrier discharge (DBD) for increasing hydrophilic property. The plasma process makes an experiment under various operating conditions of the DBD, which operating conditions are treatment time, plasma gas mixture ratio, the plasma source supply frequency. Two kinds of SUS substrate, SUS-304 and SUS 316L, were used. Discharge frequency has a crucial impact on equipment performance and gas treatment. After the plasma treatment of a SUS plate, highly improved wettability was noted. But, when high oxygen supply, the substrate damaged seriously.

• 한국염색가공학회지
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• 제9권6호
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• pp.10-17
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• 1997

In order to improve the anti-static property of several hydrophobic fibers by sputter etching, polyester, polypropylene and poly(p-phenylene sulfide) have been etched by sputtering in the presence of argon gas and the resulting anti-static property investigated by half time decay, the time of water permeation, weight loss rate and scanning electron microscope(SEM). The temporary change and durability of anti-static property of samples treated with sputter etching were evaluated. The results were as follows; 1) Half time decay of samples treated with sputter etching were decreased about 18~38%. According to increasing sputter etching time, half time decay is decreased. 2) The wettability and weight loss rate of treated samples were increased remarkably. According to the SEM photographs, many microcraters on the substrate surface by the sputter etching were observed. 3) Although the washing treatment and the time elapsed after treatment are allowed longer, the variation of half time decay hardly can find.

• 한국응용과학기술학회지
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• 제33권3호
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• pp.449-458
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• 2016

Detergency and surface active properties of mixed anionic surfactants with amphoteric and nonionic were investigated. Sodium dodecyl sulfate (SDS) and ammonium dodecyl sulfate (ADS) as anionic surfactants and cocamidopropyl betaine (CAPB) as an amphoteric surfactant were used. Nonionic surfactants, which are butyl glucoside (BG), octyl glucoside (OG), decyl glucoside (DG), lauryl dimethylamine oxide (AO) and saponin were also used. To study the synergy effects of mixed SDS/ADS anionic surfactant systems, amphoteric and nonionic surfactants were added into the mixed anionic surfactants. Investigated properties of surfactant mixtures were critical micelle concentration (CMC), surface tension (${\gamma}$), wettability. In addition, based on these properties, detergency of each sample was examined. Surfactant mixtures are anionics (SDS/ADS), anionic/amphoteric/nonionic (SDS/ADS/CAPB/saponin), and anionic/nonionic (SDS/ADS/BG/saponin, SDS/ADS/OG/saponin, SDS/ADS/DG/saponin, and SDS/ADS/AO/saponin). With the addition of amphoteric and nonionic to mixed anionic surfactants, CMC and ${\gamma}$ were decreased. Addition of CAPB, which is amphoteric, showed the best property at CMC and ${\gamma}$. Furthermore, as the chain length of hydrocarbon in alkyl glucosides was increased, the CMC and ${\gamma}$ were enhanced. However, the wettability did not exactly match up with CMC and ${\gamma}$. The surfactant mixture, which contained DG, showed the best performance at wetting time. Detergency was measured at various temperatures ($15^{\circ}C$, $30^{\circ}C$, $50^{\circ}C$). The cleaning performance was enhanced by increasing washing temperature. Moreover, detergency was influenced by not only CMC and ${\gamma}$ but also wettability. Although CMC and ${\gamma}$ were not minimum at surfactant mixture that included DG, the best cleaning performance showed in that sample.

• Elastomers and Composites
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• 제36권2호
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• pp.102-110
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• 2001

Nonylphenoxy poly(ethylene) ethanol homologues, caster oil poly(ethylene) ethanol homo-logues 및 sodium perfluoroalkyl carboxylates의 세 가지 종류 계면활성제를 사용하여 고무인상재의 젖음성 향상 연구를 수행한 결과 불소 관능기가 도입된 sodium perfluoroalkyl carboxylates 계면활성제의 경우 다른 계면활성제를 사용한 경우에 비해 고무인상재의 초기 표면에너지 값은 유사했으나 평형상태에 이른 후의 표면에너지 값이 낮아 치아와의 젖음성이 가장 우수한 것으로 나타났다. 또한, 수소가스의 발생을 억제시키고 미세부 재현성을 높이기 위해 소포제를 사용한 결과 젖음성이 향상된 sodium perfluoroalkyl carboxylates를 포함한 조성에 소포제를 첨가할 경우 인열물성이 약 40% 이상 증가하였는데, 이는 소포제가 고무인상재 내부의 반응으로 생성되는 수소가스의 발생을 억제하기 때문이다. 따라서, 소포제는 고무인상재의 표면특성에는 크게 영향을 미치지 않으면서 인상재 내부에 발생되는 기포를 효과적으로 억제 혹은 제거하여 고무 인상재의 기계적물성을 향상시킴을 알 수 있었다.

• 한국의류학회지
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• 제25권1호
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• pp.61-70
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• 2001

As important factors determining human sensorial comfort, liquid moisture management and surface properties of heat resistant workwear materials were examined. To figure out liquid moisture management properties of the test materials, absorption capacity, rate of absorption, and evaporation properties were assessed. A modified GATS(Gravimetric Absorbency Testing System) was used to measure the liquid moisture accumulation associated with the wicking of liquid moisture from sweating skin. The GATS procedure measures demand wettability of materials to take up liquid in a direction perpendicular to the fabric surface and it was modified to incorporate a special test cell and cover to assess absorption behavior in the presence of evaporation. Fabric stiffness, smoothness, number and the length of surface fibers, and an estimate of the contact area between the skin and fabric surface were measured to characterize the mechanical and surface properties of the test materials. Also an estimate of the force with which a fabric clings to moist skin was made using as wet-cling index.