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기공성 알루미나 산화 피막을 이용한 나노 금속화합물의 제조
오한준(Han-Jun Oh),정용수(Yongsoo Jeong),지충수(Choong-Soo Chi) 한국표면공학회 2010 한국표면공학회지 Vol.43 No.5
Porous Al₂O₃ film can be utilized as template for fabrication of nano-structured materials. Porous anodic alumina layer as template was prepared by anodization of aluminum in oxalic acid, and the pore diameter and barrier-type alumina layer can be controlled for proper anodizing parameter by widening process in H₃PO₄ solution. The SiO₂ nanodot and Ni nanowire was fabricated using anodic alumina template and their characteristics were investigated using SEM and TEM with EDS. Especially the growth mechanism of SiO₂ nanodot in alumina membrane compared with thinning of the alumina barrier layer during anodization was also investigated.
오한준(Han-Jun Oh),정용수(Yongsoo Jeong),지충수(Choong-Soo Chi) 한국표면공학회 2010 한국표면공학회지 Vol.43 No.5
For an application as templates of high performance with proper pore size and shape, porous anodic alumina films were prepared by anodization in oxalic acid, and formation behaviors of anodic alumina layer as well as dissolution process in acid solution have been investigated. The surface characteristics on anodic alumina layer were shown to be dependent on the fabrication parameters for anodization. For the dissolution behaviors of anodic alumina, the thickness of the barrier-type alumina layer decreased linearly with the rate of 0.98 ㎚/min in H3PO4 solution at 30℃. The changes of the anodic alumina layers were analyzed by SEM and TEM.
수용액 및 비수용액에서 양극산화법으로 형성된 TiO₂ 나노튜브의 구조 연구
김병조(Byungjo Kim),문성모(Sungmo Moon),정용수(Yongsoo Jeong),김병관(Byungkwan Kim) 한국표면공학회 2010 한국표면공학회지 Vol.43 No.4
TiO₂ nanotubes were formed on Ti by anodizing in 1 M H₃PO₄ + 0.3 M HF and 0.1 M NH₄F + 2% H₂O in ethylene glycol, and their surface and cross-sectional morphologies were observed using FE-SEM as a function of anodizing time and applied voltage. The cross-section of the TiO₂ nanotubes was readily observed from the small pieces of nanotubes remaining near the scratch lines after scratching of the anodized surface. TiO₂ nanotubes was observed to grow faster and thicker in non-aqueous solution than in aqueous solution. Diameter of TiO₂ nanotubes was proportional to the applied voltage, irrespective of the type of the electrolyte, and it is recommended to use non-aqueous solutions for the preparation of larger diameter of TiO₂ nanotubes.
구연산 기반 구리-니켈 합금도금에 대한 분광학적/전기화학적 특성 연구
이주열(Joo-Yul Lee),임성봉(Seong-Bong Yim),김만(Man Kim),정용수(Yongsoo Jeong) 한국표면공학회 2011 한국표면공학회지 Vol.44 No.3
We investigated the spectroscopic and electrochemical properties of the citrate-based CuNi solution at different solution pH and analyzed various surface properties of CuNi codeposition layer. By combining UVVisible spectroscopic data with potentiodynamic polarization curves, it could be found that the complexation of Ni<SUP>2+</SUP>-citrate pair was completed at lower solution pH than Cu<SUP>2+</SUP>-citrate pair and was affected by the coexistent Cu<SUP>2+</SUP> ions, while the complexation between Cu<SUP>2+</SUP> ions and citrate was not sensitive to the presence of Ni<SUP>2+</SUP> ions. Also, the electron transfer from cathode to Cu<SUP>2+</SUP>-citrate and Ni<SUP>2+</SUP>-citrate was hindered by strong complexation between Cu<SUP>2+</SUP>/Ni<SUP>2+</SUP> ions and citrate and so apparent codeposition current densities were reduced as the solution pH increases. CuNi codeposited layers had a higher Cu content when they were prepared at high pH solution due to the suppression of Ni deposition, and when codeposition was executed in an agitated condition due to the acceleration of mass transfer of Cu<SUP>2+</SUP> ions in the solution. Actually, solution pH had little effect on the surface morphology and deposits orientation, but greatly influenced the corrosion resistance in 3.5% NaCl solution by modifying the chemical composition of CuNi layers and so pH 3 was expected as the most suitable solution pH in the viewpoint of corrosion coatings.
주조용 Al-Si-Cu 알루미늄 합금의 기계가공 및 주조된 표면에서의 양극산화피막 형성
문성모(Sungmo Moon),남윤경(Yoonkyung Nam),양철남(Cheolnam Yang),정용수(Yongsoo Jeong) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.6
The anodic oxidation behaviour of a cast component of AC2A Al alloy with machined surface and ascast surface was investigated in sulfuric acid solution. The anodized specimen showed relatively uniform and thick anodic oxide films on the as-cast surface, while non-uniform and very thin oxide films were formed on the machined surface. Non-anodized as-cast surface was observed to be covered with thick oxide scales and showed a number of second-phase particles containing Si, while non-anodized machined surface showed no oxide scales and relatively very small number of Si particles. Thus, the very limited growth of anodic oxide films on the as-cast surface was attributed to the presence of thick oxide scales and Si-containing second-phase particles on its surface.