• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1177-1182
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• 2012

The corrosion resistance of 316L stainless steel coated with NiO-YSZ (Ni added yttria stabilized zirconia) was examined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carried out using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR) were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increased with increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ film contained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by several orders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare 316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt % NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate.

• 한국표면공학회지
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• 제33권4호
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• pp.233-240
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• 2000

A novel electrostatic spraying method to solidify molten zinc coating layer was studied by SEM and measurement of sample's temperature. The sprayed droplets also served as nucleation sites in the solidification reaction of molten zinc but might leave the pitting mark by impinging on its surface especially at high spray pressure. Our experimental results showed that electric field could change the sprayed particle trajectories and assist the fine droplets to attach on the surface. Thus, by reducing the spray pressure and by applying the electric voltage higher than -20 KV to charge the droplets electrostatically, we could produce the spangle free galvanized coating layer without pitting.

• 한국초전도ㆍ저온공학회논문지
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• 제10권1호
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• pp.6-9
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• 2008

We have investigated the MOD process successfully for the fabrication of the YBCO thick film on the $LaAlO_3$(001) single crystalline substrate. The cracking problem in YBCO thick film, a serious problem in the conventional TFA-MOD method, could be overcome with a careful control of precursor materials. Thus coating solution was prepared for the YBCO thick film by using fluorine-free precursor material. The precursor solutions were coated on the LAO(001) single crystalline substrate using the dip coating method, calcined at the temperature up to $500^{\circ}C$, and fired at various high temperatures for 2 h in a reduced oxygen atmosphere. Optimally processed YBCO thick film exhibited high critical current($I_c$) over 200 A/cm-width at 77K in self-field.

• 한국해양공학회지
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• 제24권5호
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• pp.67-74
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• 2010

Chromate conversion coating is a coating technique used to passivate aluminum, zinc, cadmium, copper, silver, magnesium, tin, and their alloys to slow corrosion. The process uses various toxic chromium compounds, which may include hexavalent chromium. The industry is developing less toxic alternatives in order to comply with substance restriction legislation, such as RoHS. One alternative is to develop a Cr-free coating solution. In this study, eco-friendly, Cr-free solutions (urethane solution S-700, organic/inorganic solution with Si LRO-317) were used. Test specimens were dried in a drying oven at $190^{\circ}C$ for 3, 5, 7, and 9 minutes. Corrosion resistance was evaluated using a salt spray test for 72 hours. The results show that the optimum corrosion resistance was achieved at $190^{\circ}C$ for five minutes for EGI and three or five minutes for HDGI, respectively. The adhesive properties of the two types of coating solutions were superior regardless of drying time.

• 멤브레인
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• 제28권3호
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• pp.180-186
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• 2018

Polyvinylidene fluoride (PVDF)의 중공사막 표면에 2번 딥코팅하여 layer-by-layer 방식으로 나노복합막을 제조하였다. 1차 코팅에서 poly(vinylsulfonic acid)(PVSA)와 Poly(styrene sulfonic acid)(PSSA)의 농도, 이온세기(Ionic strength, IS) 등을 변화시키며 막을 제조하였으며, 2차 코팅 용액으로는 Poly(ethyleneimine) 10,000 ppm I.S = 0.3으로 고정하였다. 막의 특성평가를 위해 각각의 100 ppm NaCl, $CaSO_4$, $MgCl_2$, 그리고 25 ppm Methyl Orange (MO) 공급액에 대한 막의 투과도와 염배제율을 측정하였다. 코팅용액의 코팅 물질의 농도가 올라갈수록 염배제율이 상승하였으며, 본 실험 조건에서 PVSA보다는 PSSA를 이용하여 제조한 중공사막이 염배제율이 높은 것을 확인하였다. 대표적으로 PSSA 30,000 ppm I.S = 1.0에서 중 공사막을 제조하였을 때 25 ppm MO용액의 투과도 1.848 LMH, 염배제율 76.3%로 가장 높은 값을 나타내었다.

• Membrane and Water Treatment
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• 제1권3호
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• pp.193-206
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• 2010

Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane hybrid system is a novel idea for reducing these membranes fouling however, when $TiO_2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, $TiO_2$ photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized $TiO_2$ was first synthesized by a sol-gel method. The synthesized $TiO_2$ was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the $TiO_2$ coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).

• Progress in Superconductivity
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• 제6권2호
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• pp.142-145
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• 2005

YBCO coated conductors have been fabricated with a newly developed oxide-precursor-based MOD process. The precursor solution was synthesized with low cost YBCO powders as starting materials and YBCO coated conductors have been deposited on IBAD substrate ($CeO_2$/IBAD-YSZ/SS). YBCO coated conductor prepared by dip coating shows transport $I_c$ of 15A/cm-w at 77 K. Microstructural and crystallographic analyses indicate that YBCO layer was grown in epitaxy with substrate and exhibited well-developed dense microstructure. Also discussed are processing and analysis of YBCO coated conductor by slot-die web coating method. It was shown that this oxide-based MOD process provides a low cost route to coated conductor with high $J_c$.

• Applied Science and Convergence Technology
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• 제24권2호
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• pp.33-40
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• 2015

$ZrO_2$ and Al-Zr composite oxide film was prepared by vacuum assisted sol-gel dip coating method and anodizing. $ZrO_2$ films annealed above $400^{\circ}C$ have tetragonal structure. $ZrO_2$ layers inside etch pits were successfully coated from the $ZrO_2$ sol. The double layer structures of samples were obtained after being anodized at 100 V to 600 V. From the TEM images, it was found that the outer layer was $Al_2O_3$, the inner layer was multi-layer of $ZrO_2$, Al-Zr composite oxide and Al hydrate. The capacitance of $ZrO_2$ coated foil exhibited about 28.3% higher than that of non-coating foil after being anodized at 100 V. The high capacitance of $ZrO_2$ coated foils anodized at 100 V can be attributed to the relatively high percentage of inner layer in total thickness. The electrical properties, such as withstanding voltage and leakage current of coated and non-coated Al foils showed similar values. From the results, $ZrO_2$ and Al-Zr composite oxide is promising to be used as the partial dielectric of high voltage capacitor to increase the capacitance.

• 한국세라믹학회지
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• 제31권9호
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• pp.1060-1068
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• 1994

Stable zirconia sol was prepared from zirconium butoxide Zr(OC4O9)4 as a precursor and ethylacetoacetate(EAcAc) or diethylene glycol(DEG) as a chelating agent under ambient agent under ambient atmosphere by Sol-Gel process. The sythesized sol was coated on 304 stainless steel substrate by dip coating, thereafter zirconia film could be obtained by heat-treatment at $600^{\circ}C$. The characteristics of coating film were determined by FT-IR, XRD, and ellipsometion peak represented Zr-O-Zr bonding of tetragonal phase was shown at 470cm-1. Crystallization of zirconia gel and film from amorphous state to tetragonal phase started at 40$0^{\circ}C$, and then transformed into monoclinic phase around $700^{\circ}C$. Zirconia film coated on 304 stainless steel substrate showed relatively low porosity of 16% when it was coated with 0.4M zirconia sol and thereafter heat-treated at 80$0^{\circ}C$ and the film was densified continuously up to 90$0^{\circ}C$. The zirconia film of 10 nm thick acted as a protective layer against oxidation up to $700^{\circ}C$.

• 폴리머
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• 제37권1호
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• pp.22-27
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• 2013

본 연구에서는 기존의 이차전지용 폴리에틸렌(PE) 분리막에 poly(meta-phenylene isophthalamide) (Nomex)를 코팅함으로써 뛰어난 내열성을 가진 coated PE 분리막을 제조하였다. 다양한 Nomex 용액 조성과 PE 분리막 코팅 조건에 따라 제조한 분리막의 기계적 및 열적 특성을 열 노출 테스트와 TMA를 이용하여 측정하였고 제조된 코팅 분리막은 기존의 PE 분리막보다 향상된 열 수축률 및 기계적 성질을 보였다. 코팅 분리막의 전기화학적 성질은 이온전도도, 순환 전위-전류법, 충방전 사이클 테스트 등을 이용해 측정하였다.