• Advances in nano research
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• 제10권3호
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• pp.211-219
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• 2021

The evaluation of the corrosion resistance of titanium with a TiO2 nanotubes top layer was carried out (TiO2 NT). These nanostructures were evolved into anatase nanoparticles without heat treatment in an aqueous medium, which is a novel phenomenon. This work analyzes the layer between the nanotube bottom and the substrate, which is thin and still susceptible to corrosion. The bottom of TiO2 nanotubes having Fluor resulting from the synthesis process changed between amorphous to crystalline anatase with a crystallite size of about 4 nm, which influenced the corrosion rates. Four kinds of samples were evaluated. A) NT by Ti anodizing; B) NTSB for Ti plates, either modifying its surface or anodizing the modified surface; C) NT-480 for anodized Ti and heat-treated (480℃) for reaching the anatase phase; D) NTSB-480 for Ti plates, first, modifying its surface using sandblast, after that, anodizing the modified surface, and finally, heat-treated to 480℃ to compare with samples having induced crystallization and passivation. Four electrochemical techniques were used to evaluate the corrosion rates. The surfaces having TiO2 nanotubes with a sandblast pre-treatment had the highest resistance to corrosion.

• 한국전기전자재료학회논문지
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• 제34권1호
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• pp.68-72
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• 2021

Aluminum is a lightweight metal and has excellent properties with regard to conductivity, workability, and strength. It has been used in various industries owing to its economic benefits. To improve upon the mechanical properties and processability by adding various alloying elements to aluminum, improving the corrosion resistance and heat resistance by electrochemically forming a porous anodic film having a thickness and hardness on the surface of the aluminum alloy is crucial. In this study, the aluminum 6061 alloy was controlled by an anodization process in a 0.3M oxalic acid electrolyte at room temperature to investigate the oxide film parameters such as porosity and thickness depending on the modulating applied voltage and time. The anodizing experiment was performed by increasing the time from 1 h to 9 h at 2-h intervals at applied voltages of 50 V and 60 V.

• 한국표면공학회지
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• 제35권6호
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• pp.401-407
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• 2002

Most of organic compounds discharged from industrial wastewater are treated by chemical oxidation, adsorption and biodegradable process. This process has been demanded a new advanced environmental wastewater treatment process. From this point of view, an electrochemical oxidation process using electrocatalysts has been developed for the destruction of organic compounds. Through this study, a ruthenium oxide/iridium oxide supported on titanium expanded metal was fabricated by thermal decomposition method and its performance was excellent during this experiment.

• 대한기계학회논문집A
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• 제31권12호
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• pp.1139-1143
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• 2007

A simple method for the fabrication of 3D micro-nano hybrid patterns was presented. In conventional fabrication methods of the micro-nano hybrid patterns, micro-patterns were firstly fabricated and then nano-patterns were formatted on the micro-patterns. Moreover, these micro-nano hybrid patterns could be fabricated on the flat substrate. In this paper, we suggested the fabrication method of 3D micro-nano hybrid patterns using micro-indentation on the anodized aluminum substrate. Since diameter of the hemispherical nano-pattern can be controlled by electrolyte and applied voltage in the anodizing process, we can easily fabricated nano-patterns of diameter of loom to 300nm. Nano-patterns were firstly formatted on the aluminum substrate, and then micro-patterns were fabricated by deforming the nano-patterned aluminum substrate. Hemispherical nano-patterns of diameter of 150nm were fabricated by anodizing process, and then micro-pyramid patterns of the side-length of $50{\mu}m$ were formatted on the nano-patterns using micro-indentation. Finally we successfully replicated 3D micro-nano hybrid patterns by hot-embossing process. 3D micro-nano hybrid patterns can be applied to nano-photonic device and nano-biochip application.

• 한국재료학회지
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• 제11권1호
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• pp.61-66
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• 2001

양극산화법을 이용하여 광촉매 특성을 나타내는 $TiO_2$ 피막을 제조하고 염료의 분해반응을 통하여 광분해 효율을 조사하였다 양극산화법에 의해 제조된 산화피막은 모두 광촉매 분해특성이 있었으며 양극산화의 조건에 따라서 $TiO_2$ 피막의 성장거동과 피막 형태에 차이가 나타났다. 황산용액에서 양극산화된 $TiO_2$ 피막은 불규칙적 인 입자모양으로 anatase와 rutile이 혼합된 조직이었으며, 인산이 첨가된 혼합용액에서 형성된 $TiO_2$는 anatase로 셀 모양의 피막형태로 생성되었다. 광촉매 특성에 적합한 양극산화의 인가 전압은 180V인 것으로 나타났다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.362-362
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• 2006

Chromic acid anodizing of aluminium is an effective process for producing a substrate which provides excellent surface properties to assembly. However, new chromium-free finishing metal treatments are being developed to reach new environmental goals. Present study deals with chromium free experimental conditions for both deoxidizing and anodizing treatments. Results clearly demonstrate the potentiality for environmentally friendly treatments to get suitable metal-adhesive performance. In particular, the role of both metal surface porosity and chemical composition has been highlighted thus allowing to propose alternative to classical treatments for aeronautic applications.

• 한국표면공학회지
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• 제35권5호
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• pp.273-278
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• 2002

We oxidized pure titanium by anodizing oxidation process in the range of 590V, within 1.5A, 30seconds. we investigated color evolution with a spectrophotometer. Surface images and surface roughness were characterized by an optical microscope and an atomic force microscope, respectively. Below the thickness of 40 $\mu\textrm{m}$, metallic yellow, blue, and pink colorsn were obtained. Lightness decreased, increased, and decreased again as titanium oxide thickness increased. Blue color at the applied voltage of 30V showed the best lightness and reproducibility with surface roughness below l$\mu\textrm{m}$. Bare titanium and titanium oxide films had micro pits more than 10ea/$\mu\textrm{m}^2$. We report that we successfully made colors by varing thickness below 40$\mu\textrm{m}$ with anodizing oxidation of method.

• 한국표면공학회지
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• 제15권2호
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• pp.69-76
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• 1982

With a view to manufacturing membranes for separation of gas mixtures, Al foils were anodized in a 2% oxalic-acid electrolyte at 40V and 80V. When anodizing was completed and Barrier layer existed at the extreme back site of the foil, the anodized foil was made to react with only electrolyte, with switching off the electric power. When the size and density of pores were changed through voltage change, the membr-anes did not show large difference in the permeability. Reacting with electrolyte, the existing Barrier layer turns into porous layer. During this process, several small pores grow from one relatively large pore, getting to the back site. The number and size of the small pores getting to the back surface increase as time passing. This change of Barrier layer into porous layer is thought to be directly related to the permeability change of the membranes. The selectivity of an anodized Al membrane was not related to the voltage change, and was high, being similar to the theoretical selctivity of metallic membranes, according to my observation.

• 한국표면공학회지
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• 제48권5호
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• pp.185-193
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• 2015

Anodization of die-casted AZ91D magnesium alloy was carried out using silicate based electrolyte solution instead of fluoride based solution to improve biocompatibility of oxidized layers. The anodic layer obtained from silicate based solution has smaller size of pore and smoother surface, resulting in lower corrosion rate in simulate body solution (SBF). Effect of enhanced structural and chemical properties in oxidized layer on biocompatibility was carefully considered.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.117-117
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• 2018