• Title/Summary/Keyword: Interpore distance

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Three-Dimensional (3D) Anodic Aluminum Surfaces by Modulating Electrochemical Method

  • Jeong, Chanyoung;Choi, Chang-Hwan
    • Journal of the Korean institute of surface engineering
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    • v.50 no.6
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    • pp.427-431
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    • 2017
  • Anodic aluminum oxide (AAO) film has recently attracted much attention as a key material for the fabrication of various nanostructures. A control of anodizing voltage (U) was employed to render different anodic aluminum oxide (AAO) nanostructures with pore diameter ($D_p$) and interpore distance ($D_{int}$) in oxalic acid. In this work, we study the effect of stepwise modulation of anodizing voltages on the shape and dimension of porous structures along the vertical direction and demonstrate the fabrication of hierarchical layers of systematically controlled three-dimensional (3D) pore profile.

Fabrication of nanomaterials using an Anodic Aluminum Oxide(AAO) thin film and their properties (AAO template를 이용한 나노 구조의 제조와 특성)

  • Yu, Hyun-Min;Lee, Jae-Hyung;Lee, Jong-In;Jung, Hak-Ki;Jung, Dong-Su
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2010.05a
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    • pp.814-817
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    • 2010
  • AAO thin films prepared by a two-step anodization process have pores that are uniform in diameter, highly ordered, and perfectly vertical with respect to the plane of the nano template. Further, the pore size and interpore distance can be easily controlled by varying the anodizing voltage and acid electrolyte. When metals are electrochemically deposited in the pores, metal nanowires that are highly ordered and uniform in diameter are formed in each pore.

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Anti-Icing Characteristics of Aluminum 6061 Alloys According to Surface Nanostructure (알루미늄 6061 합금의 표면 나노 구조물 변화에 따른 방빙 특성 연구)

  • Rian, Kim;Chanyoung, Jeong
    • Corrosion Science and Technology
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    • v.21 no.6
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    • pp.476-486
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    • 2022
  • Recently, aluminum 6061 instead of copper alloy is used for cooling heat exchangers used in the internal combustion of engines due to its economic feasibility, lightweight, and excellent thermal conductivity. In this study, aluminum 6061 alloy was anodized with oxalic acid, phosphoric acid, or chromic acid as an anodizing electrolyte at the same concentration of 0.3 M. After the third anodization, FDTS, a material with low surface energy, was coated to compare hydrophobic properties and anti-icing characteristics. Aluminum was converted into an anodization film after anodization on the surface, which was confirmed through Energy Dispersive X-ray Spectroscopy (EDS). Pore distance, interpore distance, anodization film thickness, and solid fraction were measured with a Field Emission Scanning Electron Microscope (FESEM). For anti-icing, hydrophobic surfaces were anodized with oxalic acid, phosphoric acid, or chromic acid solution. The sample anodized in oxalic acid had the lowest solid fraction. It had the highest contact angle for water droplets and the lowest contact hysteresis angle. The anti-icing contact angle showed a tendency to decrease for specimens in all solutions.

Effects of Heat Treatments of Aluminum Substrate on Nanopore Arrays in Anodic Alumina (열처리가 알루미나 나노기공의 배열에 미치는 영향)

  • Cho, S.H.;Oh, H.J.;Kim, S.S.;Joo, E.K.;Yoo, C.W.;Chi, C.S.
    • Korean Journal of Materials Research
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    • v.12 no.11
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    • pp.856-859
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    • 2002
  • To investigate effects of heat treatments including grain size control in substrate aluminum on nanopore arrays in anodic alumina template, aluminum was heat treated at $500^{\circ}C$ for 1h. The heat treated aluminum was anodized by two successive anodization processes in oxalic solution and the nanopore arrays in anodic alumina layer were studied using TEM and FE-SEM. The highly ordered porous alumina templates with 110 nm interpore distance and 40 nm pore diameter have been observed and the pore array of the anodic alumina has a uniform and closely-packed honeycomb structure. In the case of alumina template obtained from heat treated aluminum substrate, the well- ordered nanopore region in anodic alumina increased and became more homogeneous compared with that from non-heattreated one.

Fabrication of Nanoporous Alumina Membrane by High- Field Anodization (고전계 전기산화에 의한 나노다공성 알루미나 멤브레인의 제조)

  • Kim, Min-Woo;Hyun, Sang-Cheol;Ha, Yoon-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.03b
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    • pp.45-45
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    • 2010
  • Nanoporous anodic alumina membranes (NAAM) with high aspect ratio, self-ordered pore array were fabricated by high-field 2-step anodization method. High voltages of 80, 100, 120 and 140 V as well as 40 V for comparison were applied to an aluminum anode with respect to a Pt cathode immersed both in 0.3M oxalic acid solution in order to investigate the self-ordering characteristics of the nanoporous structure. The pore structures, including interpore distance, pore size, pore density, and porosity as well as the ordering characteristic were analyzed using field-enhanced scanning electron microscopy (FE-SEM) and the corresponding Fourier-transformed images. The nanoporous structure could be produced for all the voltage conditions, but the well-ordered through-hole pore without a branched structure seemed to occur only at 40 and 140 V. It turned out that the growth rate under 140 V high-field anodization was about 40 times higher than under conventional 40 V mild anodization, which enabled the fast fabrication of self-ordered, high aspect ratio NAAMs.

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Investigation of Nanopore Shape Formed on an Aluminum Roll Mold with Various Anodizing Conditions (다양한 양극산화 공정조건에 따른 롤 금형 표면에 형성되는 나노포어 형상에 대한 연구)

  • Ryu, In Gon;Han, Eui Don;Kim, Byeong Hee;Seo, Young Ho
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.26 no.2
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    • pp.166-171
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    • 2017
  • This study analyzes the effect of anodizing conditions on nanopore formation on a cylindrical aluminum roll. In general, a nanopore is formed at the center of a concave base-pattern. Occasionally, multiple nanopores are formed on a single base-pattern. However, to control the diameter and interpore distance precisely, single nanopores are required. In this study, the ratio of the number of single nanopores to the total number of nanopores was investigated by varying anodizing conditions such as electrode area, electrolyte concentration, and rotation speed of the roll mold. The areal ratio of the counter-electrode to the working electrode (aluminum), electrolyte concentration, and the roll-mold rotation speed were varied from 0.4% to 42%, 0.07 M to 0.3 M, and 5 rpm to 75 rpm, respectively. The experimental results showed that the single-nanopore ratio increased with increasing counter-electrode area and electrolyte concentration. However, the rotation speed had no significant effect on nanopore shape.

The Formation of Anodic Oxide Film by Anodizing Voltage and Time of 6061 Aluminum Alloy (알루미늄 6061 합금의 양극 산화 인가 전압과 시간에 따른 표면의 산화피막층 형성 거동)

  • Park, Youngju;Jeong, Chanyoung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.1
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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.

Shape Control of Anodic Aluminum Oxide and Effect as Support of Silicon Powder Electrode (양극산화알루미늄의 형상제어와 이를 이용한 실리콘 분말 전극 지지체 효과)

  • Song, Ju-Seok;Ha, Jong-Keun;Kim, Yoo-Young;Park, Dong-Kyu;Ahn, In-Shup;Ahn, Jou-Hyeon;Cho, Kwon-Koo
    • Journal of Powder Materials
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    • v.22 no.4
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    • pp.240-246
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    • 2015
  • Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at $4^{\circ}C$. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.