• 한국분말재료학회지
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• 제21권4호
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• pp.260-265
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• 2014

In this study, in order to increase surface ability of hardness and corrosion of magnesium alloy, anodizing and sealing with nano-diamond powder was conducted. A porous oxide layer on the magnesium alloy was successfully made at $85^{\circ}C$ through anodizing. It was found to be significantly more difficult to make a porous oxide layer in the magnesium alloy compared to an aluminum alloy. The oxide layer made below $73^{\circ}C$ by anodizing had no porous layer. The electrolyte used in this study is DOW 17 solution. The surface morphology of the magnesium oxide layer was investigated by a scanning electron microscope. The pores made by anodizing were sealed by water and aqueous nano-diamond powder respectively. The hardness and corrosion resistance of the magnesium alloy was increased by the anodizing and sealing treatment with nano-diamond powder.

• 한국표면공학회지
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• 제52권1호
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• pp.30-36
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• 2019

In this study, we investigated the effects of anodizing time, dyeing treatment time, and variations in coloring concentration on the color of an AA5052 alloy processed by dye-treated anodizing. The outward color of the anodized film changed to deep red according to increases in anodizing time, dyeing treatment time, and coloring concentration; accordingly, lightness $L^*$ decreased and saturation $a^*$ and $b^*$ increased. The concentration of the dye and the UV-visible absorbance showed a nearly perfect linear relationship, allowing a quantitative analysis of the absorbed dye. Because the quantity of absorbed dye increased as anodizing time, dyeing treatment time, and coloring concentration increased, the outward color of the anodized film deepened. In addition, from the GD-OES depth profile, we found that the dye was preferentially absorbed on the surface of the porous anodized film.

• 한국분말재료학회지
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• 제21권2호
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• pp.114-118
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• 2014

In this study, an aluminum oxide layer for sealing treatment of nano-diamond powder was synthesized by anodizing under constant current. The produced pore size and oxide thickness were investigated using scanning electron microscopy. The pore size increased as the treatment time increased, current density increased, sulfuric acid concentration decreased, which is different from the results under constant voltage, due to a dissolution of the oxide layers. The oxide layer thickness by the anodizing increased as temperature, time, and current density increased. The results of this study can be applied to optimize the sealing treatment process of nano-diamond particles of 4-10 nm to enhance the resistances of corrosion and wear of the matrix.

• Corrosion Science and Technology
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• 제15권4호
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• pp.166-170
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• 2016

The combined process of porous type anodizing and desiccation treatment was applied to improve wettability of A1050 aluminum alloy. The water contact angles of anodized samples were increaseds considerably with desiccation treatment. However, there was no considerable effect of polishing and anodizing time on water contact angle. The corrosion behavior with the treatments was investigated electrochemically. The corrosion resistance of the samples in 3.5 mass% NaCl solutions increased with higher contact angle. Anodized and desiccated samples showed better corrosion resistance than un-desiccated samples around rest potential region.

• 한국표면공학회지
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• 제47권3호
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• pp.121-127
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• 2014

In this study, in order to improve corrosion resistance and wear resistance of aluminum, surface treatment was made by anodizing with oxalic acid solution and sealing with nano-diamond powder. Average size of nano-diamond powder was 30nm. Anodizing with oxalic acid made many pores in the aluminum oxide layer. Pore size and oxide thickness were investigated by scanning electron microscope (SEM). Pore size increased as temperature increased and voltage increased. It was possible to make oxide layer with pore diameter more than 50 nm. Oxide thickness increased as temperature and voltage and treatment time increased. Oxide layer with above $10{\mu}m$ thickness was made. Aluminum oxide layer with many pores was sealed by water with nano-diamond powder. Surface morphology was investigated by SEM. After sealing treatment with nano-diamond powder, corrosion resistance, wear resistance and hardness increased.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.257-257
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• 2017

• 한국표면공학회지
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• 제51권2호
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• pp.87-94
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• 2018

Various sealing techniques were applied to the anodized 5083 aluminum alloy for marine environment to reduce corrosion and cavitation erosion damage. Electrochemical experiments and cavitation erosion tests were conducted to evaluate the corrosion resistance and cavitation resistance of the anodic oxide film treated with sealing in natural seawater solution. Then, damaged surface morphology was analyzed by scanning electron microscope(SEM) and 3D microscope. As the results of the electrochemical experiments, it was observed that the surface damage of all the experimental conditions in the anodic polarization experiment was locally grown by the combination of crack and corrosion damage. In the Tafel analysis, the corrosion resistance of all sealing treatment conditions was improved compared to the anodizing. On the other hand, cavitation erosion tests showed that the anodizing and all the sealing treatment conditions generated local pit damage by cavitation erosion attack and grew to crater damage in the observation of damaged surface by SEM. Also, the weight loss and the surface damage depth measured with the experiment time presented that most of the sealing treatment conditions showed better cavitation erosion resistance than the anodizing, and they had an incubation period at the beginning of the experiment.

• 한국생산제조학회지
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• 제21권1호
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• pp.90-94
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• 2012

This study evaluates the strength of surface treatment parts using the hard anodizing method to the aluminum alloy brake disks. In order to achieve weight reduction of vehicles, Eco-friendly cars parts of the high-quality and competitive price is to equip. Especially while pursuing parts of weight reduction, it has to maintain the strength of the surface of the brake by nature. To enhance surface strength of aluminum alloy, we use hard anodizing technology in the surface treatment. This study is resulted of 3 times greater the hardness value of the hard anodized specimen than the aluminum alloy specimen for the lightweight parts of EV brake disk

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.28-34
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• 2011

티타니아 나노튜브(Titania nanotube, TNT)는 티타늄을 $F^-$ 이온을 함유한 전해질 하에서 전기로 양극산화 시켜 제조 한 튜브형태의 박막으로 광학 활성을 가진다. 전해질은 증류수와 포름아마이드를 용매로 사용하였으며 HF, NaF, $NH_4F$ 를 $F^-$이온 성분으로 사용하였다. 전압과 양극산화 시간이 증가함에 따라 TNT의 길이와 직경도 증가하였다. 양극산화에 의해 제조된 TNT는 매우 규칙적인 튜브형태였으며, 제조 조건에 따라 길이는 최대 13.7 ${\mu}m$이었다. 생성된 티타니아는 비정질이었으며 열처리에 의해 아나타제 결정으로 바뀌었다.

• 한국표면공학회지
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• 제51권1호
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• pp.1-10
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• 2018

Anodic oxidation treatment of metals is one of typical surface finishing methods which has been used for improving surface appearance, bioactivity, adhesion with paints and the resistances to corrosion and/or abrasion. This article provides fundamental principle, type and characteristics of the anodic oxidation treatment methods, including anodizing method and plasma electrolytic oxidation (PEO) method. The anodic oxidation can form thick oxide films on the metal surface by electrochemical reactions under the application of electric current and voltage between the working electrode and auxiliary electrode. The anodic oxide films are classified into two types of barrier type and porous type. The porous anodic oxide films include a porous anodizing film containing regular pores, nanotubes and PEO films containing irregular pores with different sizes and shapes. Thickness and defect density of the anodic oxide films are important factors which affect the corrosion resistance of metals. The anodic oxide film thickness is limited by how fast ions can migrate through the anodic oxide film. Defect density in the anodic oxide film is dependent upon alloying elements and second-phase particles in the alloys. In this article, the principle and mechanisms of formation and growth of anodic oxide films on metals are described.