• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.427-428
• /
• 2009

The authors investigated anomalous nanoporous structures of aluminum oxides during the Al anodization process. We implemented two-steps anodizing process for the electrolyte of oxalic acid. As increasing DC voltages, lattice constants are proportionally increased. For the curved surface, the surface electric field was distorted so that the nanoporous pipe channel changed to a cone-type shape. We confirmed the periodicity by using the FFT(Fast Fourier Transform) analysis.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1495-1496
• /
• 2011

Anodic aluminum oxide (AAO) nanotemplates for nano electronic device applications have been attracting increasing interest because of ease of fabrication, low cost process, and possible fabrication in large area. The size and density of the nanostructured materials can be controlled by changing the pore diameter and the pole density of AAO nanotemplate. In this paper, AAO nanotemplate was fabricated by second anodization method. In addition, effects of electrolyte and anodization voltate on the microstructure of porous alumina films were investigated. Vertically well aligned pores had the average pore sizes of 15-70 nm and the length of approximately 40 ${\mu}m$.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.83-89
• /
• 2012

Due to the potential importance and usefulness, usage of highly ordered nanoporous anodized aluminum oxide can be broadened in industry, when highly ordered anodized aluminum oxide can be placed on a substrate with controlled thickness. Here we report a facile route to highly ordered nanoporous alumina with the thickness of hundreds-of-nanometer on a silicon wafer substrate. Hexagonally or tetragonally ordered nanoporous alumina could be prepared by way of thermal imprinting, dry etching, and anodization. Adoption of reusable polymer soft molds enabled the control of the thickness of the highly ordered porous alumina. It also increased reproducibility of imprinting process and reduced the expense for mold production and pattern generation. As nanoporous alumina templates are mechanically and thermally stable, we expect that the simple and costeffective fabrication through our method would be highly applicable in electronics industry.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2007.11a
• /
• pp.96.2-96.2
• /
• 2007

• Journal of the Korean Ceramic Society
• /
• v.45 no.4
• /
• pp.191-195
• /
• 2008

Highly ordered silver nanowire with a diameter of 10 nm was arrayed by electroless deposition in a porous anodic aluminum oxide(AAO) membrane. The AAO membrane was fabricated electrochemically in an oxalic acid solution via a two-step anodization process, while growth of the silver nanowire was initiated by using electroless deposition at the long-range-ordered nanochannels of the AAO membrane followed by thermal reduction of a silver nitrate aqueous solution by increasing the temperature up to $350^{\circ}C$ for an hour. An additional electro-chemical procedure was applied after the two-step anodization to control the pore size and channel density of AAO, which enabled us to fabricate highly-ordered silver nanowire on a large scale. Electroless deposition of silver nitrate aqueous solution into the AAO membrane and thermal reduction of silver nanowires was performed by increasing the temperature up to $350^{\circ}C$ for 1 h. The morphologies of silver nanowires arrayed in the AAO membrane were investigated using SEM. The chemical composition and crystalline structure were confirmed by XRD and EDX. The electroless-deposited silver nanowires in AAO revealed a well-crystallized self-ordered array with a width of 10 nm.

• Journal of the Korean Electrochemical Society
• /
• v.24 no.1
• /
• pp.7-12
• /
• 2021

In this study, we investigated the formation of the metal oxide nanostructure by anodization of aluminum 3104H18 alloy. The anodization was performed in pyrophosphoric acid (H4P2O7) electrolyte. By the control of anodization condition such as concentration of electrolyte, anodization temperature and applied voltage, nanoporous or nanofiber structures were obtained. The optimal anodization condition to form nanofiber structures are 75 wt% of H4P2O7 at 30 V and 20℃. When anodization was performed at over 40 V, nanoporous structures were formed due to accelerated dissolution reaction rate of nanofiber structures or increasing thickness of channel wall.

• Journal of Animal Science and Technology
• /
• v.65 no.1
• /
• pp.258-270
• /
• 2023

Climate change has worsened droughts and floods, and created conditions more likely to lead to pathogen contamination of surface water and groundwater. Thus, there is a growing need to disinfect livestock water. Ultraviolet (UV) irradiation is widely accepted as an appropriate method for disinfecting livestock water, as it does not produce hazardous chemical compounds and kills pathogens. However, UV-based disinfection inevitably consumes electricity, so it is necessary to improve UV disinfection effectiveness. Aluminum-based reflective nanolens arrays that enhanced the effectiveness of a continuous-flow UV water disinfection system were developed using electrochemical and chemical processes, including electropolishing and two-step anodization. A continuous UV disinfection system was custom designed and the parts were produced using a three-dimensional printer. Electropolished aluminum was anodized at 40 and 80 V in 0.3 M oxalic acid, at 120 and 160 V in 1.0 M phosphoric acid, and at 200 and 240 V in 1.5 M citric acid. The average nanolens diameters (D) of the aluminum-based reflective nanolens arrays prepared using 40, 80, 120, 160, 200, and 240 V anodization were 95.44, 160.98, 226.64, 309.90, 296.32, and 339.68 nm, respectively. Simple UV reflection behind irradiated water disinfected Escherichia coli O157:H7 in water more than did the non-reflective control. UV reflection and focusing behind irradiated water using an aluminum-based reflective nanolens array disinfected E. coli O157:H7 more than did simple UV reflection. Such enhancement of the UV disinfection effectiveness was significantly effective when a nanolens array with D 226.64 nm, close to the wavelength of the irradiated UV (254 nm), was used.

• Journal of the Korean Society for Heat Treatment
• /
• v.31 no.1
• /
• pp.6-11
• /
• 2018

The anodic oxidation behavior of Si-containing aluminum alloy for diecasting was investigated. Especially, the property changes during anodization both on aluminum 1050 and 9 weight percentage silicon containing aluminum (Al-9Si) alloys were analyzed by the static current test. In order to fabricate a uniform anodic oxidation film by effect of Al-Si compound, nitric acid containing hydrofluoric acid had been used as a desmutter for aluminum alloy after alkaline etching. It was found that the level of voltage of Al-9Si alloy during the static current test was almost as double as higher than aluminum 1050 through anodization. By adding hydrofluoric acid in the nitric acid electrolyte, the silicon compound on the surface was removed, and the optimum amount of added hydrofluoric acid could be derived. It was also observed that the size of silicon compound formed on the surface could be refined by heat treatment at $500^{\circ}C$ and followed water quenching.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.4
• /
• pp.923-928
• /
• 2010

Anodic aluminum oxide (AAO) nanotemplates for nano electronic device applications have been attracting increasing interest because of ease of fabrication, low cost process, and possible fabrication in large area. The size and density of the nanostructured materials can be controlled by changing the pore diameter and the pole density of AAO nanotemplate. In this paper, nano porous alumina films AAO nanotemplate was fabricated by second anodization method using sputterd Al films. In addition, effects of electrolyte temperature and anodization voltate on the microstructure of porous alumina films were investigated. As the electrolyte temperature was increased from $8^{\circ}C$ to $20^{\circ}C$, the growth rate of nanoporous alumina films was increased from 86.2 nm/min to 179.5 nm/min. The AAO nanotemplate fabricated with optimal condition had the mean pore diameter of 70 nm and the pore depth of $1\;{\mu}m$.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.6
• /
• pp.239-244
• /
• 2005

Nano-sizedporearrayswerepreparedbytheself-organizationprocessesoftheanodicoxidationusingthealuminumplatewith99.999$\%$purity.Sincethealuminumplatehasaroughsurface,thealuminumplateof1mmthicknesswasanodizedafterthepre-treatmentsofpressing,mechanicalpolishing,thermaloxidation,chemicalpolishing,andelectrochemicalpolishing.Thediameterofthenano-sizedporesandthethicknessofbarrierlayercanbecontrolledbyappliedvoltage.Thethicknessofaluminamembranecanalsobecontrolledbytheanodizingcurrent.Thenano-sizedporeswithdiameterof60$\~$120nm,thedistancebetweenthenearestporesof30$\~$60nm,andthethicknessof6$\~$7Wwereobtainedbytheanodicoxidationprocess.Theporewideningprocesswasemployedforobtainingtheone-channelwithflatsurfacebecausetheporesofthealuminamembranepreparedbythefixedvoltagemethodshowsthestructureoftwo-channelwithroughsurface.