• 공업화학
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• 제20권2호
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• pp.191-194
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• 2009

양극산화(anodization)에 의해 얻어지는 다공성 알루미나는 균일한 규칙성의 나노 구조를 지니며, 이를 제어하는 공정이 비교적 쉽고 경제적이어서 최근 연구가 광범위하게 진행되고 있다. 본 연구에서는 1차로 옥살산(oxalic acid)을 이용하여 양극 산화를 한 산화물 만들고, 이 산화물을 선택적으로 제거한 뒤 생기는 알루미늄 표면의 벌집모양의 패턴에 붕산(boric acid)을 이용하여 2차 양극산화를 하여 알루미늄 산화물 나노 돗(nanodot)을 형성하였다. 정렬된 정육면체의 모서리에 20 nm 높이의 나노 돗이 배열되어 있는 구조를 형성하기 위한 최적의 조건을 조사하였다. 알루미늄 산화물 나노 돗 층에 금을 코팅하여 육각벌집모양으로 배열된 금 나노 돗 층을 형성하였다. 이 표면은 향후 바이오센서에 적용될 것으로 기대된다.

• 한국정보통신학회논문지
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• 제14권4호
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• pp.923-928
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• 2010

양극산화 알루미늄(anodic aluminum oxide, AAO) 나노템플레이트는 제작이 쉬우며, 저비용, 대면적 제작이 가능하다는 장점으로 인해 이를 나노 전자소자 제작에 응용하려는 많은 연구가 이루어지고 있다. 이러한 나노템플레이트를 이용하면 기공의 직경이나 밀도를 변화킴으로써 나노구조의 물질의 크기나 밀도를 제어할 수 있다. 따라서 본 논문에서는 나노 전자소자 제작에 응용할 수 있는 AAO 나노템플레이트를 2단계 양극산화법에 의해 제조하였다. 이를 위해 기존의 알루미늄 판 대신 실리콘 웨이퍼 상에 DC 마그네트론 스퍼터법으로 $2{\mu}m$ 두께의 알루미늄 박막을 증착하였고, 전해액으로 사용한 옥살산 용액의 온도 및 양극산화 전압에 따른 다공성 알루미나 막의 미세구조를 조사하였다. 전해액 온도가 $8^{\circ}C$에서 $20^{\circ}C$로 높아짐에 따라 다공성 알루미나 막의 성장속도는 86.2 nm/min에서 179.5 nm/min으로 증가하였다. 최적 조건에서 제작된 AAO 나노 템플레이트의 기공 직경 및 깊이는 각각 70 nm와 $1\;{\mu}m$이었다.

• 한국표면공학회지
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• 제51권6호
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• pp.415-420
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• 2018

The possibility of an improvement in heat dissipation performance of aluminum alloy heat sink for shipboard LED luminaries through plasma electrolytic oxidation (PEO) was investigated. Four different PEO coatings were produced on aluminum alloy 5052 in silicate based alkaline solution by varying current density ($50{\sim}200mA/cm^2$). On voltage-time response curves, three stages were clearly distinguished at all current densities, namely an initial linear increase, slowdown of increase rate, and steady state(constant voltage). It was found that the increase in current density caused the breakdown voltage to increase. Two different surface morphologies - coralline porous structure and pancake structure - were confirmed by SEM examination. The coralline porous structure was predominant in the coatings produced at lower current densities (50 and $100mA/cm^2$) while under high current densities(150 and $200mA/cm^2$) the pancake structure became dominant. The coating thickness was measured and found to be in a range between about $13{\mu}m$ and $44{\mu}m$, showing increasing thickness with increasing current density. As a result, $100mA/cm^2$ was proposed as an effective process parameter to improve the heat dissipation performance of aluminum alloy heat sink, which could lower the LED operating temperature by about 30%.

• 마이크로전자및패키징학회지
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• 제26권1호
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• pp.35-39
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• 2019

현재까지 다공성 알루미나 구조물은 대표적으로 양극산화 방법으로 구현되어 오고 있다. 양극산화 방법을 통해 규칙적인 배열을 가진 알루미늄 산화 피막은 쉽게 만들 수 있지만, 복합 구조물 형태를 가진 산화피막은 상대적으로 구현하기가 어렵다. 본 연구는 인산용액에서 양극산화 인가전압에 따른 피막 기공 크기, 두께 및 구조물 형태 변화를 관찰하고자 한다. 다층 복합 산화물 구조물 구현을 위해 양극산화 인가전압 조건을 조절하였고, 실험 조건은 10% 인산용액에서 양극산화 인가전압 100 V와 120 V로 각각 수행하였다. 실험 결과는 각 조건에 따라 다공성 구조물과 복합 구조물 형태의 산화물 구조를 구현할 수 있었다.

• Corrosion Science and Technology
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• 제21권3호
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• pp.200-208
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• 2022

Aluminum alloy is used by adding various elements according to the needs of the industry. Aluminum alloys such as 5052 and 6061 are known to possess excellent corrosion resistance by adding Mg. Despite their excellent physical properties, corrosion can occur. To solve this problem, an anodization technique generally can improve corrosion resistance by forming an oxide structure with maximized hydrophobic properties through coatings. In this study, the anodizing technique was used to improve the hydrophobicity of aluminum 5052 and 6061 by creating porous nanostructures on top of the surface. An oxide film was formed by applying anodizing voltages of 20, 40, 60, 80, and 100 V to aluminum alloys followed by immersion in 0.1 M phosphoric acid for 30 minutes to expand oxide pores. Contact angle and corrosion characteristics were different according to the structure after anodization. For the 5052 aluminum, the corrosion potential was improved from -363 mV to -154 mV as the contact angle increased from 116° to 136°. For the 6061 aluminum, the corrosion potential improved from -399 mV to -124 mV when the contact angle increased from 116° to 134°.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1209-1212
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• 1995

This paper presents a capacitive humidity sensor using porous silicon layers formed tom the anodization of p-type silicon in HF solution. The upper electrodes consist of many aluminum strips over porous silicon, between which the porous silicon is etched away. The sensor showed a good sensitivity(20pF/%RH) and lineaity in the range of 40%RH$\sim$80%RH, a hysteresis of ${\pm}2%$ RH, and a slow transient response. These preliminary resluts show that futher improvement can still be expected.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.98-103
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• 1999

The application field of porous mold is more and more expended. A mixture of alumina and cast iron is used for making porous mold using slip and vacuum casting method in this study. Slip casting is a process that slurry is poured into silicon rubber mold, dried in vacuum oven, debinded and sintered in furnace, In this procedure, slurry is composed of powder, binder, dispersion agent, and water. Vacuum casting is a technique for removing air bubbles existed in the slurry under vacuum condition. Since ceramics has a tendency of over-shrinkage after sintering, cast iron is used to compensate dimensional change. The results shows that sintering temperature has a great effect on characteristics of alumina-cast iron composite sintered parts. Finally ceramic-metal composite sintered mold can be used for aluminum alloy casting of shoe mold using this process.

• 한국전기전자재료학회논문지
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• 제16권9호
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• pp.801-806
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• 2003

In recent years, there has been large interest in the fabrication of the self organized nanoscale structures since not only their potential utilization in electronic, optoelectronic, and magnetic devices but also their fundamental interest such as uniformity and regularization. An attractive candidate of these materials is anodic porous alumina film(Al$_2$O$_3$) which is formed by the anodization of aluminum in an appropriate acid solution. In this study to fabricate the porous alumina film with very uniform and nearly parallel pores the anodization was carried out under constant voltage mode in 0.3M oxalic acid as an electrolyte. The hexagonally ordered arrays with a few $\mu\textrm{m}$ in size two-dimensional polycrystalline structure were obtained of which pore densities were 1.1${\times}$10$\^$10//$\textrm{cm}^2$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1573-1575
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• 2004

An alumina membrane with nano-sized pores was fabricated by anodic oxidation. The shape and structure of the pore on alumina membrane were changed according to the roughness of aluminum surface. The shape and structure of the nano-sized pre were investigated according to purity of aluminum substrate for the anodization process. The aluminum substrates with 99.5% and 99.999% purities were used. The aluminum substrate(99.5%) was anodized after the processes of pressing, mechanical polishing, chemical polishing, and electrochemical polishing. The nano-sized pores with the pore size of 50 - 100nm, the cell size of 20-50nm and the thickness of $10{\mu}m{\sim}45{\mu}m$ were obtained. Even though the electrochemical polishing was used for the aluminum substrate (99.999%), the same characteristics as the aluminum substrate (99.5%) was obtained. The alumina membrane prepared by anodization for 5 min using fixed voltage method shows the pore with irregular shape. The pore shape was changed to regular shape after pore widening process.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.177-186
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• 1998

For the purpose of finding out the sound field characteristics in a cavity of a rectangular enclosure with foamed aluminum lining, analytical and experimental studies are performed with random noise input. Experimental method using two-microphone impedance tube measures the absorption coefficients and the impedances of simple sound absorbing materials. Measured acoustical parameters of the test samples are applied to the theoretical analysis to predict sound pressure field in the cavity. The sound absorp- tion effects from measurements are compared to prediction in both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure.