• Corrosion Science and Technology
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• 제9권6호
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• pp.233-238
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• 2010

Hot-dipped Al-Mg-Si coatings to alternate Zn and Zn alloy coatings for steel were examined on metallographic structure, corrosion resistance, sacrificial ability, formation and growth of inter-metallic compounds, and mechanical properties. Near the eutectic composition of quasi-binary system of Al-$Mg_2Si$, very fine eutectic structure of ${\alpha}$-Al and $Mg_2Si$ was obtained and it showed excellent corrosion resistivity and sacrificial ability for a steel in sodium chloride solutions. Formation and growth of Al-Fe inter-metallic compounds at the interface of substrate steel and coated layer was suppressed by addition of Si. The inter-metallic compounds layer was usually brittle, however, the coating layer did not peel off as long as the thickness of the inter-metallic compounds layer was small enough. During sacrificial protection of a steel, amount of hydrogen into the steel was more than ten times smaller than that of Zn coated steel, suggesting to prevent hydrogen embrittlement. Al-Mg-Si coating is expected to apply for several kinds of high strength steels.

• 센서학회지
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• 제30권6호
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• pp.451-455
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• 2021

Porous copper bromide (CuBr) films are highly advantageous for detecting ammonia (NH₃). The fabrication of porous CuBr films requires complex high-temperature processes or multistep processes. Herein, we report the uncomplicated preparation of porous CuBr films by a spin-coating method and the films' excellent NH₃ sensing properties. The porous films were prepared by spin-coating 100, 150, and 200 mM CuBr solutions, and then dried in a vacuum oven for 2 h. All the films showed a high NH₃ response; in particular, the film prepared using a 100 mM CuBr solution showed an extremely high response (resistance ratio = 852) to 5 ppm NH₃. The film also showed fast response and recovery times, 272 s and 10 s respectively, even at room temperature. The outstanding NH₃ sensing characteristics were explained in relation to the porosity and thickness of the prepared films. The high-performance NH₃ sensors used in this study can be used for both indoor air quality and environmental monitoring applications.

• 한국응용과학기술학회지
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• 제34권3호
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• pp.525-535
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• 2017

내열성이 우수하며, 태양광 모듈의 유리 표면에 방담성(antifogging) 및 방오성(antifouling)을 동시에 부여하여 효율을 향상시키기 위한 친수성 코팅액을 제조하기 위해 초친수성과 우수한 방담효과를 나타내는 Tween 20과 데카플루오로부탄과 폴리에틸렌글리콜 성분으로 구성된 불소계면활성제 수용액에 방오성 부여를 위하여 나노실리카를 분산하였다. 고온 처리에서 나노실리카의 함량에 따른 방담 효과는 모든 코팅액이 우수하였으나, 방오 효과는 나노실리카의 함량이 6 wt%일 때부터 나타났다. 불소계면활성제의 함량이 증가할수록 초기 접촉각이 증가하며 방담 효과도 500회 wiping까지 잘 유지되었다. 방오 효과 역시 불소계면활성제의 함량에 상관없이 우수하여 불소계면활성제의 적절한 첨가량은 0.1 wt%이상 이면 충분하였다. AFM 결과로부터 불소계면활성제가 0.1 wt%에서 0.3 wt%가 첨가된 경우 코팅 표면의 프랙탈구조가 확실히 나타나 방오성 향상에 기여하였다. 코팅된 유리의 투과도는 불소계면활성제가 0.1 wt% 첨가된 TL-1의 경우가 가장 높았으며 더 많은 양의 불소계면활성제를 첨가할 경우 오히려 투과도 향상은 미미하였다. 이러한 결과는 앞의 AFM 결과에서 나타난 표면 조도가 높으며 프랙탈구조 형성도 잘 일어난 TL-1 코팅액의 결과와 잘 일치하는 것이다.

• 폴리머
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• 제24권3호
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• pp.389-398
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• 2000

폴리카보네이트 표면에 spin-coating한 유/무기 복합 코팅막을 자외선 경화와 가열(12$0^{\circ}C$, 12시간)처리함으로써 약 4~13 $\mu\textrm{m}$ 두께의 투명한 내마모성 유/무기 복합코팅막을 제조하였다. 코팅용액은 무기상과 유기상을 각각 0 : 100, 20 : 80, 30 : 70, 50 : 50, 80 : 20 중량비로 혼합한 다음 광개시제, 증감제 및 계면활성제를 첨가하여 제조하였다. 무기상은 TEOS와 실란커플링제 MPTMS을 1 : 2 혹은 2 : 1몰비로 흔합하여 졸ㆍ겔 반응으로 제조하였으며, 유기상은 2관능형 urethane acrylate 올리고머, 다관능형 TMPTA와 HDDA를 4:3:3 wt% 비율로 흔합하여 제조하였다. 유/무기복합상의 화학적 변화는 FT-IR, $^{29}$ Si-NMR로 분석하였으며, 열분석과 코팅층 표면 형상은 TGA/DSC, SEM, AFM으로 분석하였다. 무기물의 함량과 실란커플링제의 첨가량이 증가 할수록 분자수준의 흔화도가 개선되고 표면 평활도와 내마모성도 향상되었다. 즉 약 10 $\AA$ 이하의 표면 거칠기와 약 15$0^{\circ}C$의 T$_{g}$를 나타내는 시료는 500회 마모시험 전후 단지 16%의 광투과도 감소만을 보인 반면에, 무코팅 폴리카보네이트를 46%의 광투과율 감소를 나타내었다..

• 동력기계공학회지
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• 제19권6호
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• pp.12-18
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• 2015

Austenitic stainless steels generally experience the occurrence of chromium-depleted zones at the boundaries, known as sensitization, caused by the carbide precipitation that takes place due to a welding process or heat treatment. Normally, the depleted zones become the focus of the intense corrosion. In this study, the Cr-free organic/inorganic hybrid solution was developed, and the artificially degraded STS316S and STS347H with the solution-coating investigated the corrosion resistance by salt spray test. Both the OIBD-1 and OIBD-2 solutions improved the corrosion resistance of STS310S and STS347H. The corrosion resistance with the OIBD-1 solution was better than that of OIBD-2 solution. Additionally, Both solutions have been proven excellence in adhesion ability, boiling water resistance and flexibility. However, a problem of rubbing after the boiling was found out to be overcome.

• Journal of Pharmaceutical Investigation
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• 제22권3호
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• pp.211-217
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• 1992

Stabilization of liposomes against degradation by bile salts has been investigated in order to develop a liposomal model system for oral drug delivery. Two polysaccharides, amylopectin (AP) and chitin (CT), were employed to coat both empty liposomes and bromthymol blue (BTB)-encapsulated liposomes by adsorption-coating techniques. Turbidity changes and BTB-release characteristics in pH 5.6 buffer solutions with or without bile salts, sodium cholate and sodium glycocholate, were observed to compare the differences between uncoated liposomes and polysaccharide-coated liposomes. Initial turbidities of both uncoated and polysaccharide-coated liposomes in buffer solution were kept constant within 3% range during 4 hours of experiments. But they were decreased in a different manner in bile salts-containing buffer solutions, showing 10% or less decrease for polysaccharide-coated liposomes and 25% or more decrease for uncoated liposomes. BTB release from uncoated liposomes has been greatly increased upto 90% after 4 hours in bile salts-containing buffer solution, which is a clue for breakdown of liposomal vesicles. However, polysaccharide-coated liposomes showed the controlled-release pattern which is proportional to square-root of time, followed by around 50% release for the same time period. Consequently, it is possible to conclude that these polysaccharide-coated liposomes might be an available system for oral delivery of a drug which is unstable in gut environment.

• 분석과학
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• 제8권3호
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• pp.293-298
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• 1995

수용액에서 pH와 일정공급전위 변화에 따른 강철심에 도금된 놋쇠의 안정성을 교류 임피던스로 측정하여 연구하였다. 일정 pH에서 일정공급전위가 양전위로 감에 따라 코팅기공저항은 감소된다. 그 사실은 일정공급전위가 양전위로 감에 따라 도금된 놋쇠층이 용액에 더 용해됨을 나타낸다. 강철심에 도금된 놋쇠의 안정성은 pH=7.1 > pH=4.0 > pH=10.0 순으로 감소한다. 위와 같은 실험결과는 전자현미경 (SEM)/에너지분산분광계(EDS)의 자료에 의해 증명된다.

• 동력기계공학회지
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• 제20권5호
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• pp.20-28
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• 2016

This study has developed an organic/inorganic hybrid solution by addition of $SiO_2$ polysilicate and Melamine to the urethane. The three types of cold rolled steel were evaluated a corrosion resistance properties by using these solutions. The urethane solution(U) and the urethane solution with $SiO_2$ polysilicate($US_7$) were generate a lot of corrosion. The urethane solution with $SiO_2$ polysilicate and melamine($US_7M_3$) was excellent in corrosion resistance, regardless of the steel type. In addition, corrosion resistance has been shown to depend on the tensile strength. The appearance of coating by U and $US_7$ solution is bumpy surface, and were a lot of fine defects. $US_7M_3$ solution is made a sophisticated molecular cross-linking structure inside the coating, it was a slick surface. Other characteristics are exhibited the excellent property for all solutions.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.614-620
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• 2012

Poly (carbonate diol), isophrone diisocyanate와 dimethylol propionic acid로부터 제조된 폴리우레탄 prepolymer의 말단 NCO 기를 aniline으로 capping시켜 aniline terminated waterborne polyurethane dispersion (ATPUD)을 합성하였다. 이 ATPUD와 순수한 waterborne polyurethane dispersion (PUD)을 각각 전도성 고분자인 polystyrene sulfonate로 도핑된 poly (3,4-ethylenedioxythiophene)[PEDOT/PSS]과 블렌딩시켜 대전방지용 코팅 용액을 제조한 후, 이것을 polycarbonate 기재 위에 도포하여 코팅 도막을 형성하였다. PEDOT/PSS가 2.5 g 이하로 적당량 첨가된 경우에는 ATPUD로 제조된 코팅 도막의 표면저항 값은 $1.0{\times}10^{11}{\sim}2.5{\times}10^8{\Omega/cm^2$로 순수한 PUD로부터 제조된 코팅 도막의 $5.0{\times}10^{11}{\sim}6.3{\times}10^9{\Omega}/cm^2$ 보다 우수한 전기전도도를 나타내었다. 그러나 PEDOT/PSS가 3.0 g으로 과량 첨가된 경우에는 ATPUD로부터 제조된 코팅 도막과 PUD로부터 제조된 코팅 도막은 비슷한 전기전도도를 나타내었다.

• Corrosion Science and Technology
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• 제7권1호
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• pp.13-15
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• 2008

Aiming at the corrosion circumstances and corrosion prevention needs of downhole oil tubes, series protective coatings for downhole oil tubes have been developed in the authors' laboratory, including a baked type coating YG-01 and an air curing type coating YG-03, etc. The performance investigation of the coatings has been done for testing their corrosion resistance, mainly including salt fog test, immersion test in oil-field waste water and various acid solutions, high temperature and high pressure test in alkali solution or $H_2S/CO_2$ environment, as well as some other performances. The investigation results show that oil tube anti-corrosion coatings developed here can endure over 4000 hrs salt fog test, over 1000 hrs immersion in various acid solutions at room temperature and in boiling oil-field waste water. In addition, the coatings can keep intact after experiencing test in alkali solution under 70 MPa pressure at $150^{\circ}C$ for 24 hrs, and in simulative sour gas environment under the total pressure of 32 MPa ($P_{H_{2}S}=3.2MPa$, $P_{CO_{2}}=3.2MPa$) at $90^{\circ}C$ for 168 hrs, which show that the coatings can be used for corrosion prevention in downhole environments with specific high temperature and high pressure, such as sour gas wells. The other testing results show the oil tube protective coatings have excellent comprehensive performance.