• Title/Summary/Keyword: Anodizing

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Study on Improvement of Corrosion Resistance and Wear Resistance by Anodizing and Sealing Treatment with Nano-diamond Powder on aluminum (알루미늄의 아노다이징과 나노 다이아몬드 분말 봉공처리에 의한 내식성과 내마모성 향상에 관한 연구)

  • Kang, Soo Young;Lee, Dae Won
    • Journal of the Korean institute of surface engineering
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    • v.47 no.3
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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.

AAO Template Morphology Controlled by Variation of Anodizing Condition (양극 산화 조건 변화에 따른 AAO Template Morphology 제어)

  • Jo, Ye-Won;Lee, Sung-Gap;Kim, Kyeong-Min
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.4
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    • pp.249-251
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    • 2015
  • In this study, the application of biosensor having a large surface area for more effective and AAO (anomic aluminium oxide) template in order to gain concentration and voltage of anodizing process morphology changes to the control of experiments were conducted. The biosensor surface may increase the response characteristics by having a large surface area. So the entrance to a little more efficient wide depth sensing experiment was carried out to obtain a structure body with a branch shape with a large surface area with increasing. Experimental results from the FE-SEM observation was obtained template morphology. As a result, depending on the anodizing time, the depth of the layer of aluminum oxide was found that it was confirmed that the deepening of the pore size changes according to anodizing condition. And measuring the detection performance according to the conditions in the electrolyte and the reaction because of blood using a biosensor measuring sensing property according to the depth of the pore depth is considered that does not have a significant impact.

The Electrochemical Properties and Mechanism of Formation of Anodic Oxide Films on Mg-Al Alloys

  • Kim, Seong-Jong;Okido, Masazumi
    • Bulletin of the Korean Chemical Society
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    • v.24 no.7
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    • pp.975-980
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    • 2003
  • The electrochemical properties and the mechanism of formation of anodic oxide films on Mg alloys containing 0-15 mass% Al, when anodized in NaOH solution, were investigated by focusing on the effects of anodizing potential, Al content, and anodizing time. The intensity ratio of Mg(OH)₂ in the XRD analysis decreased with increasing applied potential, while that of MgO increased. Mg(OH)₂ was barely detected at 80 V, while MgO was readily detected. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. The intensity ratio of the β phase increased with aluminum content in Mg-Al alloys. During anodizing, the active dissolution reaction occurred preferentially in β phase until about 4 min, and then the current density increased gradually until 7 min. The dissolution reaction progressed in α phase, which had a lower Al content. In the anodic polarization test in 0.017 mol·$dm^{-3}$ NaCl and 0.1 mol·$dm^{-3}$ Na₂SO₄ at 298 K, the current density of Mg-15 mass% Al alloy anodized for 10 min increased, since the anodic film that forms on the α phase is a non-compacted film. The anodic film on the α phase at 30 min was a compact film as compared with that at 10 min.

Fabrication of Nano Master with Anti-reflective Surface Using Aluminum Anodizing Process (양극산화공정을 이용한 반사방지 성형용 나노 마스터 개발)

  • Shin, H.;Park, Y.;Seo, Y.;Kim, B.
    • 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.

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A Study on the Growth and Burning of Anodic Oxide Films on Al6061 Alloy During Anodizing at Constant Voltages (Al6061 합금의 정전압 아노다이징 피막의 형성거동 및 버닝에 대한 연구)

  • Moon, Sanghyuck;Moon, Sungmo;Song, Pungkeun
    • Journal of the Korean institute of surface engineering
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    • v.53 no.1
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    • pp.15-21
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    • 2020
  • In this study, growth and burning behavior of 6061 aluminum alloy was studied under constant anodic voltages at various temperatures and magnetic stirring rates in 20% sulfuric acid solution by analysing I-t curves, measuring thickness and hardness of aluminum anodic oxide (AAO) films, observations of surface and cross-sectional images of AAO films. AAO films were grown continuously at lower voltages than 18.5V but burning occurred when a voltage more than 19V was applied in 20% H2SO4 solution at 20±0.5℃ and 200 rpm of magnetic stirring. The burning was always related with an extremely large increase of anodic current density with anodizing time, suggesting that high heat generation during anodizing causes deteriorations of AAO films by chemical reaction with acidic solutions. The burning resulted in decreases of film thickness and hardness, surface color brightened and formation of porous defects in the AAO films. The burning voltage was found to decrease with increasing solution temperature and decreasing magnetic stirring rate. The decreased burning voltages seem to be closely related with increased chemical reactions between AAO films and hydrogen ions.

A Study on the manufacturing of porous membrane by the aluminum anodizing (알루미늄 양극산호를 이용한 다공성 견막 제조에 관한 연구)

  • Yoon, Jae-Hwan;Kang, Tak
    • Journal of the Korean institute of surface engineering
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    • v.13 no.4
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    • pp.221-227
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    • 1980
  • When anodizing the Al in the acid electrolyte, it is well known that the parallel pores grow continuously perpendicular to the surface. This fact can be used for the manufacturing of the porous membrane, if thc pores pass through the anodized foil. Anodizing both surfaces of the Al-foil spontaneously in 20$^{\circ}C$, 2% oxalic acid under tile potentiostatic condition, it is found that the harrier layer remaining in the midst of the foil finally disappears and thc pores pass through the foil. And examined the porous structure change when the voltage is changed during the anodizing treatment. From the result, it is revealed that the new pores and cell grow, adjusting themselves to the final voltage. The characteristic of the porous membrane is greatly dependent upon the diameter of the pore and the cell. So studied the relationship between the voltage and the diameter of the pore and the cell quantitatively with the aid of field-assisted dissolution concept. And derived the following two equation, Pi = 8.32Vi, Ci = 26.80Vi. These equations are in good accord with the experimental data above 30V, but do not accord nuder 30V.

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Influences of Anodizing and Thermal Oxidation on the Galvanic Corrosion between Aluminium and Titanium and GECM (GECM과 Al 및 Ti 간의 갈바닉 부식에 미치는 양극산화 및 열산화의 영향)

  • Kim, Young-Sik;Lim, Hyun-Kwon;Sohn, Young-Il;Yoo, Young-Ran;Chang, Hyun-Young
    • Korean Journal of Metals and Materials
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    • v.48 no.6
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    • pp.514-522
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    • 2010
  • Graphite epoxy composite material (GECM) shows high specific strength and its application in the aerospace industry is gradually increasing. However, its application would induce galvanic corrosion between GECM and metallic materials. This work focused on the effects of anodizing and thermal oxidation on galvanic corrosion in a 3.5% NaCl solution between GECM and aluminium and titanium. In the case of anodized aluminium, galvanic corrosion resistance to the GECM was greatly improved by the anodizing treatment regardless of area ratio. In the case of anodized titanium, the anodizing by a formation voltage of 50V increased corrosion resistance of titanium in galvanic tests. Thermal oxidation of titanium also improved corrosion resistance of Ti to GECM.

Optimization of Polishing Conditions for Anodized Inner Surfaces in Large Hydraulic Devices (아노다이징 처리된 대형 유압장치의 내면에 대한 연마 조건의 최적화)

  • Choi, Su-Hyun;Cho, Young-Tae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.7
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    • pp.14-21
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    • 2019
  • Large-diameter hydraulic devices such as the hydraulic reservoir in aircraft that serves to balance the hydraulic pressure in the various hydraulic devices in the cabin and to store hydraulic oil are operated by the internal piston systems. However, since this operates in an environment with high temperature and humidity, it may cause the inner surface to flake during its operation. Therefore, an anodizing surface treatment is applied to improve the corrosion resistance, abrasion resistance, and smooth operation. However, anodizing increases the surface roughness. Accordingly, the polishing process that improves the surface roughness after anodizing is important. However, the existing polishing process is performed manually, which results in an inefficient process. Therefore, in this study, we selected the optimum polishing conditions for effective polishing using the experimental design to improve the polishing process for the $Al_2O_3$ film that forms after anodization. Through experiments, we confirmed that the surface uniformity after polishing was superior as the feed rate was slower when the same polishing time had been applied.

Study on Methods of Enhancement and Measurement of Corrosion Resistance for Subsea Equipment made of Aluminum (알루미늄으로 제작된 심해 장비의 부식 저항 능력 향상 방법 및 측정 방법 조사)

  • Seo, Youngkyun;Jung, Jung-Yeul
    • Plant Journal
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    • v.16 no.3
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    • pp.47-52
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    • 2020
  • This study investigated the methodologies to enhance the corrosion resistance and the ways to measure for subsea equipment made of aluminum. The methodologies for the anticorrosion were cathodic protection, conversion coating, anodizing and organic coating. The simply analyzed ways to measure the corrosion resistance were Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS), Glow discharge optical emission spectrum spectroscopy (GD-OES), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Scanning Vibrating Electrode Technique (SVET), contact angle and interfacial tension. The most widely used tools for increasing the corrosion resistance were the anodizing and the organic coating. Many ways were evenly used to measure corrosion. The methods more frequently utilized were SEM for the surface investigation and the contact angle to evaluate the corrosion resistance.

Fabrication and Electrical Properties of Anodic Aluminum Oxide Membrane with Various Anodizing Temperatures for Biosensor (바이오센서로 응용을 위한 양극산화알루미늄의 양극산화 온도에 따른 제작 및 전기적 특성)

  • Yeo, Jin-Ho;Lee, Sung-Gap;Kim, Yong-Jun;Lee, Young-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.6
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    • pp.394-398
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    • 2014
  • We fabricated the electrolyte-dielectric-metal (EDM) sensor on the base of AAO (anodic aluminum oxide) template with variation of the anodizing temperature. When a surface is immersed or created in an aqueous solution, a discontinuity is formed at the interface where such physicochemical variables as electrical potential and electrolyte concentration change significantly from the aqueous phase to another phase. Because of the different chemical potentials between the two phases, charge separation often occurs at the interfacial region [1]. This interfacial region, togeter with the charged surface, is usually known as the electrical double layer (EDL) [2]. The structural and electrochemical properties of AAO sensor were investigated for applications in capacitive pH sensors. To change the thickness of the AAO template, the anodizing temperature was varied from $5^{\circ}C$ to $20^{\circ}C$, the thickness of the AAO template invreased from 300 nm to 477 nm. The pH sensitivity of sensors with the anodizing temperature of $20^{\circ}C$ showed the highest value of 56.4 mV/pH in the pH range of 3 to 11. The EDM sensor with the anodizing temperature of $20^{\circ}C$ exhibited the best long-term stability of 0.037 mV/h.