• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.562-565
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• 2013

The high purity Al foil, which has an enlarged surface area by electrochemical etching process, has been used as an anode for an aluminum electrolytic capacitor. Etch pits are randomly distributed on the surface because of the existence of surface irregularities such as impurity and random nucleation of pits. Even though a large surface area was formed on the tunnel-etched Al, its applications to various fields were limited due to non-uniform tunnel morphologies. In this work, the selective electrochemical etching of aluminum was carried out by using a patterned mask fabricated by photolithographic method. The formation of etch pits with uniform distribution has been demonstrated by the optimization of experimental conditions such as current density and etching solution temperature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.135-135
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• 1998

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1805-1810
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• 2010

We present a simple, cost-effective, and fast fabrication process for three-dimensional (3D) microstructures; this process is based on multi-step electrochemical etching of metal foils which facilitates the mass production of 3D microstructures. Compared to electroplating, this process maintains uniform and well-controlled material properties of the microstructure. In the experimental study, we perform single-step electrochemical etching of aluminum foils for the fabrication of 2D cantilever arrays. In the single-step etching, the depth etch rate and bias etch rate are measured as $1.50{\pm}0.10 {\mu}m/min$ and $0.77{\pm}0.03 {\mu}m/min$, respectively. Using the results of single-step etching, we perform two-step electrochemical etching for 3D microstructures with probe tips on cantilevers. The errors in height and lateral fabrication in the case of the fabricated structures are $15.5{\pm}5.8% $ and $3.3{\pm}0.9%$, respectively; the surface roughness is $37.4{\pm}9.6nm$.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.1-7
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• 1990

We present a theoretical investigation on the etching of an Al solid by $SiCl_4$ molecules at a collision energy of 600 eV. The classical trajectory method is employed to calculate Al etching yields, degree of anisotropy, kinetic energy distribution and angular distribution. The calculated results are compared with the reaction of a Cu solid by $SiCl_4$. The major products of the reaction are aluminum monomers and dimers together with considerable quantities of multimers. The Al solid shows better etching yield and better anisotropy than the Cu solid. This is consistent with the problem in the CMOS micro-fabrication of the CuAl and CuAlSi alloys. The relevance of these calculations for the dry etching of CuAl alloy is discussed.

• Biomedical Science Letters
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• v.14 no.2
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• pp.105-113
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• 2008

The objective of this study was to evaluate the influence of surface modifications on the bonding characteristics and cytotoxicity of specific titanium porcelain bonded to milling titanium and cast titanium. Milling titanium and cast titanium samples were divided into 8 test groups. These groups are as follow: i) sandblasted with particles of different size of $220{\mu}m\;and\;50{\mu}m$, ii) different sequences of sandblasting treatment and etching treatment, iii) etched with different etching solutions, and iv) preheated or not. The surface characteristics of specimens were characterized by the test of mean roughness of surface and SEM. The bond strength of titanium-ceramic systems was measured by using three-point bending test and SEM. The results show that the mean roughness of surface of sample sandblasted with $220{\mu}m$ aluminum oxide increased and bond strength were higher than sample sandblasted with $50{\mu}m$ aluminum oxide. The mean roughness of surface decreased, but the bond strength increased when the samples sandblasted with $220{\mu}m$ aluminum oxide were preheated. The sample sandblasted with $220{\mu}m$ aluminum oxide after oxidized with occupational corrosive agent I (50% NaOH, 10% $CuSO_4{\cdot}5H_2O$) and II (35% $HNO_3$, 5% HF) showed higher bond strength than sample oxidized with 30% $HNO_3$ after sandblasted with $220{\mu}m$ aluminum oxide. Group NaCuNF220SP (milling Ti: 35.3985 MPa, casting Ti: 37.2306 MPa) which was treated with occupational corrosive agent I (50% NaOH, 10% $CuSO_4{\cdot}5H_2O$) and II (35% $HNO_3$, 5% HF), followed by sandblasting with $220{\mu}m$ aluminum oxide and preheating at $750^{\circ}C$ for 1 hour showed the highest bond strength and significant differences (P<0.05). The method for modifying surface of titanium showed excellent stability of cells.

• Journal of the Korean institute of surface engineering
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• v.24 no.4
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• pp.215-221
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• 1991

Microstructure evolution during low temperature vapor deposition exhibits wel-developed columnar structure mainly owing to geometrical shadowing effect of surface roughness. It is concluded that this structure is concided with many theoretical models suggested so far. In case of aluminum nitride film deposition consisted of etching and nitriding step employing ECR plasma, the rougher the surface before etching, the finer and more cone-and-whisker structure can be developed. In turn, this fine structure affects the formation and growth of columnar as well as offers many sites available for mechanical lock-up. Conclusively, the formation of well-defined columnar structures depends on the initial surface roughness.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.265.1-265.1
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• 2013

Nanoporous anodic aluminum oxide (AAO), a self-ordered hexagonal array has various applications for nanofabrication such as nanotemplate, and nanostructure. In order to obtain highly-ordered porous alumina membranes, Masuda et al. proposed a two-step anodization process however this process is confined to small domain size and long hours. Recently, alternative methods overcoming limitations of two-step process were used to make prepatterned Al surface. In this work, we confirmed that there is a specific tendency used a PDMS stamp to obtain a pre-patterned Al surface. Using the nanoindentaions of a PDMS stamp as chemical carrier for wet etching, we can easily get ordered nanoporous template without two-step process. This chemical etching method using a PDMS stamp is very simple, fast and inexpensive. We use two types of PDMS stamps that have different intervals (800nm, 1200nm) and change some parameters have influenced the patterning of being anodized, applied voltage, soaking and stamping time. Through these factors, we demonstrated the patterning effect of large scale PDMS stamp.

• Journal of the Korean institute of surface engineering
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• v.25 no.3
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• pp.150-157
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• 1992

A recovery process of pure alumina powder from the wasted aluminum etching solution of electrolytic condenser works was studied. The possibility of this process was considered in the basis of thermodynamic data nad physico-chemical properties for the recovered materials were tested. In order to obtain pure alumina, Fe3+ and Cu2+ in the solution as impurities were solvent-extracted, respectively, and then, Al3+ was precipitated by changing the pH of the solution. As the results, more than 99.9% of Al3+ in the solution was recovered by the precipitation method. The weight of the precipitate was reduced to about 65 wt.% of the original one by calcination and the sizes of the recovered powders were in order of 3-5$\mu\textrm{m}$. The precipitates were transformed to $\alpha$-Al2O3 at the calcination temperature about 120$0^{\circ}C$.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.335-342
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• 2006

Metal aluminum, of which has a low standard reduction potential, participates in the electrochemical oxidation reaction and results in the structural change and accompanying property variation of aluminum and its oxide film. Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of high density etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the capacitor electrode. Anodization of aluminum in acid solution at low temperature makes a nanoporous aluminum oxide layer which can be used for the fabrication template of nanostructural materials. Electrochemical characteristics of aluminum turn the metal aluminum into functional materials and it will bring the diverse applications of metal aluminum.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.697-701
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• 2009

A simple method for the fabrication of porous nano-master for the anti-reflection effect on the transparent substrates is presented. In the conventional fabrication methods for antireflective surface, coating method using materials with low refractive index has usually been used. However, it is required to have a high cost and long processing time for mass production. In this paper, we developed a porous nano-master with anti-reflective surface for the molding stamper of the injection mold, hot embossing and UV imprinting by using the aluminum anodizing process. Through two-step anodizing and etching processes, a porous nano-master with anti-reflective surface was fabricated at the large area. Pattern size Pore diameter and inter-pore distance are about 130nm and 200nm, respectively. In order to replicate anti-reflective structure, hot embossing process was performed by varying the processing parameters such as temperature, pressure and embossing time etc. Finally, antireflective surface can be successfully obtained after etching process to remove selectively silicon layer of AAO master.