• 공업화학
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• 제10권2호
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• pp.212-217
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• 1999

기체투과 특성을 관찰하기 위해 양극산화에 의해 세공직경의 크기가 서로 다른 상부층과 하부층으로 이루어진 이중기하구조의 다공성 알루미나막을 제조하였다. 양극산화는 황산 전해질 하에서 직류에 의한 정전류법으로 행하였으며, 양질의 막을 얻기 위해 열산화, 화학연마, 전해연마 등의 전처리를 한 후 양극산화를 행하였다. 양극산화에 의한 알루미나 막의 제조에서 세공직경은 전해질의 종류 및 농도, 전해 온도, 전류밀도 등에 의존하는데, 전류밀도를 극도로 낮추어 세공직경이 20 nm 이하인 상부층을 제조하고 전류밀도를 높여서 세공직경이 36 nm인 하부층을 제조하였다. 막의 두께는 전기량에 의해 조절되어 상부층의 두께는 약 $6{\mu}m$이었으며 하부층을 포함하는 막의 총 두께는 약 $80{\sim}90{\mu}m$로 제조되었다. 제조된 막은 가압법에 의한 기체투과 실험을 행하였다. 제조된 막의 기체투과 기구는 Knudsen 흐름을 따르는 것을 확인하였다.

• 공업화학
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• 제9권4호
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• pp.536-541
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• 1998

본 연구에서는 시판용 99.8% 금속알루미늄을 수산전해액에서 정전류 방식에 의하여 양극산화하여 다공성 알루미나 막을 제조하는 실험을 행하였다. 전기화학 반응은 표면반응으로 양극산화에 앞서 알루미늄판을 열산화, 화학연마 및 전해연마 등의 전처리를 행하였으며, 반응온도, 전기량, 수산전해질 농도 및 전류밀도의 변화에 따라 양극산화를 시행하여 형성된 다공성 알루미나 막의 세공크기와 분포, 세공밀도 및 막와 두께를 조사하였다. 양극산화에 의해 제조된 다공성 알루미나 막의 기하구조는 직선적인 원통형 세공을 가지며, 세공직경이 45~100 nm 범위로 세공분포가 매우 균일하고, 세공밀도가 $10{\sim}30{\times}10^8$개/$cm^2$로 우수한 세라믹막의 특성을 갖는 한외여과막을 제조할 수 있었다.

• 한국화재소방학회논문지
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• 제11권3호
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• pp.15-23
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• 1997

In this study, the alumina for gas sensor was prepared by anodic oxidation. It was stable thermally and chemically, and pore diameter and pore distribution was uniform. And the shape of pore was cylinderical. The aluminum plate was carried out by the thermal oxidation, chemical polishing and electropolishing pretreatment. The pore diameter, pore size distribution, pore density and thickness of alumina was observed with the change of reaction temperature, electrolyte concentration and current density. As a results, It was able to use for carrier because alumina which was prepared by anodic oxidationhas uniform pore size distribution.

• 한국표면공학회지
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• 제42권3호
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• pp.109-115
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• 2009

Magnesium is one of the lightest metals, and magnesium alloys have excellent physical and mechanical properties such as high stiffness/weight ratios, good castability, good vibration and shock absorption. However their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To improve these defects, many techniques are developed. Micro arc oxidation(MAO) is a one of the surface treatments under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy. In this study, the characteristics of anodic film were examined after coating the AZ31B magnesium alloy through the MAO process. MAO was carried out in potassium hydroxide, potassium fluoride, and various concentration of sodium silicate in electrolyte. The morphology and chemical composition of the coating layer were characterized by SEM, XRD, EPMA and EDS. The hardness of anodic films was measured by micro-vickers hardness tester. As a result, the morphology and composition of anodic film were changed by concentration of sodium silicate. Thickness and Si composition of anodic film was increased with increasing concentration of sodium silicate in electrolyte. The hardness of anodic film was highly increased when the concentration of sodium silicate was above 40 g/l in electrolyte.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.35-43
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• 2012

Highly ordered and perforated anodic aluminum oxide membranes were prepared by anodic oxidation and subsequent removal of the barrier layer. By using these homemade anodic aluminum oxide membranes as templates, metal selenide nanowires and nanotubes were synthesized. The structure and composition of these one-dimensional nanomaterials were studied by field emission scanning electron microscopy as well as transmission electron microscopy and energy dispersive X-ray spectroscopy. The growth process of metal selenide inside anodic aluminum oxide channel was traced by investigating the series of samples using scanning electron microscopy after reacting for different times. Straight and dense copper selenide and silver selenide nanowires with a uniform diameter were successfully prepared. In case of nickel selenide, nanotubes were preferentially formed. Phase and crystallinity of the nanostructured materials were also investigated.

• 한국표면공학회지
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• 제33권5호
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• pp.309-318
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• 2000

The 6063 Aluminium alloy were electrocolored and anodized at the same time in addition of $CoSO_4$, $FeSO_4$, in the electrolyte and investigated by AES/SAM. It was found that the thickness of anodic oxide film is increased linearly in DC type, and DC combined AC type, the more ratio of anodic Portion in AC, the more increased of anodic film thickness. The color of anodic film was changed from silver to yellow when the increase of the ratio of cathodic portion in AC. Also the increase of $CoSO_4$, $FeSO_4$ in the electrolyte, the coloring time is decreased. From the AES/SAM results, the element of anodic oxide film are Al,O and S. The result of depth profile, the most of the S distributed on the surface and the more S is in DC combined AC type than only DC type.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1576-1578
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• 2004

The alumina membrane with nano sized pore was prepared from aluminum by anodic oxidation to apply for storage equipment, gas sensor and stamper. The pore size and cell size of the pores are controlled by anodic oxidation voltage. The alumina thickness was controlled by etching process using 0.2M $H_3PO_4$. The thickness of alumina on Si wafer was very accurately controlled by anodic oxidation time. Nickel with nano-sized grain was electroplated on the Au layer on silicon wafer. The fabricated pores on alumina membrane was the thickness of $7{\sim}10{\mu}m$ with straight nano-sized pore of 307${\sim}$120nm. The alumina by the etching process shows smooth surface. The size of Ni grain was 130nm and 250nm for 10mA/$cm^2$and 20mA/$cm^2$of electroplating currents, respectively.

• 한국분말재료학회지
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• 제18권1호
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• pp.56-63
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• 2011

Recently, $TiO_2$ nanotubes have considerably researched because of their novel application about photocatalysis, dye-sensitized solar cells (DSSCs), lithium ion battery, etc. In this work, self-standing $TiO_2$ nanotube arrays were fabricated by anodic oxidation method using pure Ti foil as a working electrode in ethylene glycole with 0.3M $NH_4F$ + $2%H_2O$. Growth behavior of $TiO_2$ nanotube arrays was compared according to temperature, voltage and time. The morphology, structure and crystalline of anodized $TiO_2$ nanotube arrays were observed by FE-SEM (field emission scanning electron microscope) and XRD (X-ray diffraction).

• 조명전기설비학회논문지
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• 제24권3호
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• pp.14-19
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• 2010

Partial anodic oxidation of Ti-mesh with a wire diameter of ~200[${\mu}m$] produces self-aligned $TiO_2$ nanotube arrays (~50[${\mu}m$] in length) on Ti-mesh substrate. The electrolyte used for anodic oxidation was an ethylene glycol solution with an addition of 1.5 vol. % $H_2O$ and 0.2 wt. % $NH_4F$. A dye-sensitized solar cell utilizing the photoanode structure of $TiO_2$-nanotube/Ti-mesh was fabricated without a transparent conducting oxide (TCO) layer, in which Ti-mesh replaced the role of TCO. The 1.93[%] photoconversion efficiency was low, which can be attributed to both insufficient dye molecules attachment and limited electrolyte flow to dye molecules. The optimized nanotube diameter and length as well as the $TiCl_4$ treatment can improve cell performance.

• 한국치위생학회지
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• 제7권4호
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• pp.471-479
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• 2007

The purpose of this study was to examine the optimum condition of impulse during the anodic spark oxidation applying pulse current as well as to find the excellent condition for HA precipitation the after electrochemical hydrothermal treatment by cathode reduction method. After anodic spark oxidation, the anodized specimen and the Pt plate connected cathode and anode, respectively. Hydrothermal treatment performed at 90, 120, $150^{\circ}C$ for 2 hours in the electrolyte containing $K_2HPO_4$, $CaCl_2{\cdot}2H_2O$, Tris(Hydroxymethyl)-$(CH_2OH)_3\;CNH_2$(Aminomethane), and NaCl. The optimum impulse voltage for anodic spark oxidation was 350V. The optimum pulse cycle measured at 10 mS. The HA crystals precipitated excellently by cathode reduction at $150^{\circ}C$ for 2 hours. The phases of anatase, rutile, and HA coating on the surface of modified titanium surface immersed in Hanks' solution for 3weeks were detected by XRD measurement and the intensity of HA crystal phase has increased by temperature and time of hydrothermal treatment. According to the our experiments, we found that Pure Ti will be good materials of bioactivity and biocompatibility.