• 한국세라믹학회지
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• 제27권5호
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• pp.583-588
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• 1990

Glass films in the binary system B2O3-SiO2 and Al2O3-SiO2 were prepared on soda-lime-silica slide glass by the dip-coating technique from TEOS and boric acid or aluminum nitrate. Thickness of the films varying with viscosity and withdrawal speed were measured and effect of composition and firing temperature on the properties such as transmittance and refractive index were investigated. nM2O3.(100-n)SiO2(M=B or Al) films containing up to 20mol% B2O3 and 40mol% Al2O3 were transparent. Maximum transmittance at visible range were obtained for the sample containing 15mol% Ba2O3 and 32.5mol% Al2O3 and heat-treated at 50$0^{\circ}C$, respectively. Refractive index of the film containing 15mol% B2O3 was mininum in the B2O3-SiO2 binary system and minimal refractive index was appeared at the film containing 32.5mol% Al2O3. In IP spectra, addition of B2O3 were increased absorption peak intensity of B-O and Si-O-B bond and addition of Al2O3 were decreased absorption peak intensity of Si-O bond, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1998-2000
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• 2005

The effects of the addition of nanocrystalline Y2O3 powder on the microstructure and superconducting properties have been investigated in YBCO films prepared by TFA-MOD process. Precursor solution doped with extra $Y_2O_3$ Powder was prepared by adding $Y_2O_3$ powder into a stoichiometic precursor solution with a cation ratio of Y:Ba:Cu=1:2:3. Coating solutions with and without $Y_2O_3$ doping were coated on $LaAlO_3(100)$ single crystal by a dip coating method, cacination and conversion heat treatments were performed at the controlled atmosphere containing water vapor Current carry capacity(Jc) of YBCO film was enhanced about 50% by $Y_2O_3$ doping. It is thought that the enhancement of Jc is due to the better connectivity of YBCO grains and/or the flux pinning by the presence of nanocrystalline $Y_2O_3$ Particles embedded in YBCO grains.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2001-2003
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• 2005

Various organic acid were used in order to prepare new metalorganic deposition solution for high quality $REBa_2Cu_3O_{7-{\delta}}$ (RE=Y, Eu, Gd) films. Prepared fluorine free MO precursor solution was coated on single crystal (001) $LaAlO_3$ (LAO) by dip coating method. Processing parameters such as oxygen partial pressure, water vapor, ramping rate and pyrolysis temperature etc havebeen controlled in order to make high $J_c$ films with a good epitaxial relationship with substrate. 0.5 micron-thick film was obtained by single coating and no crack appeared after calcination. Oxygen partial pressure was varied in the range of $100{\sim}1,000 ppm$ and conversion heat treatment was carried out at the temperature of $725{\sim}765^{\circ}C$. A critical transition temperature $(T_{c0})$ of 90K and a critical transport current density $(J_c)$ of $>0.5MA/cm^2$ (77K and self-field) were demonstrated for the YBCO film on (001) oriented LAO substrates with a thickness of 0.5 micron. $I_c$ was determined by utilizing a transport measurement. SEM and XRD investigations confirmed that films were grown epitaxially onto the LAO single crystal substrate. It is thought that fluorine free new MOD solutionis promising for high quality REBCO films.

• 한국염색가공학회지
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• 제15권3호
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• pp.161-167
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• 2003

The preparations of deodorizing fibers using $TiO_2$ have been investigated. The fibers were coated with $TiO_2$ for the purpose of deodorizing by dipping fibers into the $TiO_2$ sol solutions and calcined at $450^\circ{C}$, $500^\circ{C}$ and $750^\circ{C}$ for 1 h after coating. The surface structure of the coated fibers was studied with XRD on the different preparation conditions of calcination temperatures. The deodorizing function of the prepared fibers was studied by the determination of the decomposing capability for $NH_3,\;CH_3SH\;and\;CH_3CHO$. The deodorant activity(D.A.) of these deodoriBing fibers was measured by chromogenic gas detector tubes. The deodorizing effect of the prepared fibers were shown to be similar for the three model compounds; 5wt% $TiO_2$ sol solution calcined at $450^\circ{C}$ < 5 wt% $TiO_2$ sol solution calcined at $500^\circ{C}$< 5 wt% TiO$_2$ sol solution calcined at $750^\circ{C}$.

• 대한금속재료학회지
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• 제50권8호
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• pp.575-582
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• 2012

Medium carbon steel was aluminized by hot dipping into molten Al or Al-1 at% Si baths. After hot-dipping in these baths, a thin Al-rich topcoat and a thick alloy layer rich in $Al_5Fe_2$ formed on the surface. A small amount of FeAl and $Al_3Fe$ was incorporated in the alloy layer. Silicon from the Al-1 at% Si bath was uniformly distributed throughout the entire coating. The hot dipping increased the microhardness of the steel by about 8 times. Heating at $700-1000^{\circ}C$, however, decreased the microhardness through interdiffusion between the coating and the substrate. The oxidation at $700-1000^{\circ}C$ in air formed a thin protective ${\alpha}-Al_2O_3$ layer, which provided good oxidation resistance. Silicon was oxidized to amorphous silica, exhibiting a glassy oxide surface.

• 대한금속재료학회지
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• 제46권2호
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• pp.58-64
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• 2008

Surface-void defects observed on the galvannealed(GA) steel sheets in Interstitial-free high-strengthened steels containing Si and Mn have been investigated using the combination of the FIB(Focused Ion Beam) and FE-TEM(Field Emission-Transmission Electron Microscope) techniques. The scanning ion micrographs of cross-section microstructure of defects showed that these defects were identified as craters which were formed on the projecting part of the substrate surface. Also, those craters were formed on the Si or Mn-Si oxides film through the whole interface between galvannealed coating and steel substrate. Interface enrichments and oxidations of the active alloying elements such as Si and Mn during reduction annealing process for galvanizing were found to interrupt Zn and Fe interdiffusion during galvannealing process. During galvannealing, Zn and Fe interdiffusion is preferentially started on the clean substrate surface which have no oxide layer on. And then, during galvannealing, crater is developed with consumption of molten zinc on the oxide layer.

• 멤브레인
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• 제25권5호
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• pp.422-430
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• 2015

본 연구에서는 silicalite-1 제올라이트 분리막 합성 시에 종결정 코팅용액 pH 변화가 제올라이트 분리층 미세구조에 미치는 영항을 고찰하였다. 75 nm 크기로 합성된 종결정은 에탄올에 분산된 후 침지코팅법으로 지지체 표면에 코팅되었으며 분산용액의 pH는 2.2, 7.0, 9.3으로 조절되었다. pH가 7인 경우, 균일하고 두께가 $3{\sim}4{\mu}m$인 silicalite-1 제올라이트 분리층이 형성되었고 분리층 결정입 크기는 100 nm로 미세하였다. 반면, pH가 2.2와 9.3인 경우, 분리층 두께가 얇고 불완전하였으며 분리층 결정입 크기도 약 $1{\mu}m$로 조대하였다. pH 7에서 완전한 제올라이트 분리층이 형성된 것은 침지코팅 중에 지지체와 종결정이 서로 다른 부호의 전하를 가져 정전기적 인력이 작용하여 균일하고 조밀하며 두껍고 다층의 종결정 코팅층이 형성되었기 때문이었다. 반면에 pH가 2.2와 9.3인 경우, 침지코팅 중에 지지체와 종결정이 서로 같은 부호의 전하를 가져 정전기적 반발력이 작용하기 때문에 불완전한 덮힘에 의하여 불완전한 분리층이 형성된다고 판단되었다. 결론적으로, 종결정 코팅용액의 pH가 silicalite-1 제올라이트 분리층의 두께, 결정립 크기 등 미세구조를 결정하는 중요한 인자임을 확인할 수 있었다.

• 한국광학회지
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• 제13권3호
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• pp.197-203
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• 2002

촉매로 사용한 HCl 농도를 달리하여 TiO$_2$ 졸(T1-0.7N, T2-2.ON)을 제조하고, 졸-겔 침지코팅법을 이용하여 TiO$_2$ 박막을 제작하였으며, 각 박막의 열처리 온도에 따른 박막의 구조적 및 광학적 특성을 측정.분석하였다. X-선 회절분석 결과 T1박막의 경우, 400-80$0^{\circ}C$의 열처리 온도에서는 아나타제 결정상을 나타내었고, 100$0^{\circ}C$에서는 루타일 결정상을 나타내었다. T2 박막의 경우, 루타일 결정상이 보다 낮은 열처리 온도인 80$0^{\circ}C$에서 나타났다. 그리고 박막의 결정성은 T2 박막이 T1 박막보다 우수하였다. 열처리 온도가 증가함에 따라 박막의 결정 크기는 증가하였으며, T2 박막의 경우 아나타제 결정의 크기는 T1 박막보다 크며 루타일 결정의 크기는 작은 것으로 측정되었다. 박막의 표면 상태는 루타일 결정상을 지닌 박막이 아나타제 결정상을 지닌 박막보다 치밀하게 형성되어졌고, 이러한 현상은 T2박막에서 보다 뚜렷하게 나타났다. 100$0^{\circ}C$에서 열처리한 박막은 300~700nm의 파장영역에서 결정상 전이에 의한 밴드갭 에너지의 변화와 박막의 조성변화로 인한 흡수의 발생, 그리고 입자의 크기 증가에 의한 산란효과로 투과율의 감소를 초래하였다. 제조된 박막의 굴절률은 열처리 온도가 증가할수록 증가하였으며, 두께와 porosity는 감소하였다. 또한 T2 박막의 굴절률은 T1 박막보다 높았고, porosity는 낮았다.

• 한국재료학회지
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• 제21권1호
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• pp.8-14
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• 2011

To improve the chemical stability of metal, the ceramic coatings on metallic materials have attracted interest from many researchers due to the chemical inertness of ceramic materials. To endure strong acids, SiOC coating on metal substrate was carried out by dip coating method using 20wt% polyphenylcarbosilane solution; SiC powder was added to the solution at 10wt% and 15wt% to improve the mechanical properties and to prevent cracks of the film. Thermal oxidation as a curing step was carried out at $200^{\circ}C$ for crosslinking of the polyphenylcarbosilane, and the coating samples were pyrolysized at $800^{\circ}C$ under argon to convert the polyphenylcarbosilane to SiOC film. The thicknesses of the SiOC coating films were $2.36{\mu}m$ and $3.16{\mu}m$. The quantities of each element were measured as $SiO_{1.07}C_{6.33}$ by EPMA, and it can be confirmed that the SiOC film from polyphenylcarbosilane was formed in a manner that was carbon rich. The hardness of the SiOC film was found to be 3.2Gpa through nanoindentor measurement. No defect including cracks appeared in the SiOC film. The weight loss of the SiOC coated stainless steel was within 2% after soaking in 10% HCl solution at $80^{\circ}C$ for one week. From these results, SiOC coating shows good potential for application to protect against severe chemical corrosion of stainless steel.

• 멤브레인
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• 제19권1호
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• pp.47-53
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• 2009

본 연구의 목적은 금속 중공사형 필터에 무기 입자를 코팅하여 금속/세라믹 복합 한외여과막을 제조하는 것이다. 직경이 2.0 mm이며 기공 크기가 $2{\sim}8{\mu}m$ 범위를 갖는 니켈 중공사 필터에 급냉건조법과 침지-건조법으로 실리카 졸과 티타니아 졸을 코팅하여 금속쎄라믹 복합 한외여과막을 제조하였다. SEM과 PMI 결과로부터 기공 크기가 50 nm 수준을 갖는 것을 확인하였다. 기공 크기는 입자 크기, 소성시간 및 온도에 따라 차이를 보였다.