• 한국레이저가공학회지
• /
• 제17권2호
• /
• pp.5-10
• /
• 2014

Aluminum has been widely used in the electric applications because of light metals. When mechanical element is periodically moving with contacting other surfaces, the anodizing process for aluminum is useful for avoiding the abrasive damage. The anodized element has quietly different characteristics with respect to the distribution of hardness and crystal structure. In this work, the laser drilling of anodized surface is studied experimentally. Fusion drilling method - laser drilling with inert gas blowing - is used. The effect of various process parameters (gas pressure, laser power, focus position) is investigated with respect to the hole size and circularity.

• 한국생산제조학회지
• /
• 제26권1호
• /
• pp.1-5
• /
• 2017

This study investigated the mechanical tearing of a cell membrane using a nanostructured alumina filter for easy and quick mechanical cell disruption. Nanostructured alumina filters were prepared by a multi-step aluminum anodizing process and nanopore etching process. Six different types of nanostructures were formed on the surface of the nanoporous alumina filters to compare the mechanical cell disruption characteristics according to the shape of the nanostructure. The prepared alumina filter was assembled in a commercial filter holder, and then, NIH3T3 fibroblast cells in a buffer solution were passed through the nanostructured alumina filter at a constant pressure. By measuring the concentration of proteins and DNA, the characteristics of mechanical cell disruption of the nanostructured alumina filter were investigated.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.407.1-407.1
• /
• 2016

Electrochromism is defined as a phenomenon which involves persistently repeated change of optical properties between bleached state and colored state by simultaneous injection of electrons and ions, sufficient to induce an electrochemical redox process. Due to this feature, considerable progress has been made in the synthesis of electrochromic (EC) materials, improvements of EC properties in EC devices such as light shutter, smart window and variable reflectance mirrors etc. Among the variable EC materials, solid-state inorganics in particular, metal oxide semiconducting materials such as nickel oxide (NiO) have been investigated extensively. The NiO that is an anodic EC material is of special interest because of high color contrast ratio, large dynamic range and low material cost. The high performance EC devices should present the use of standard industrial production techniques to produce films with high coloration efficiency, rapid switching speed and robust reversibility. Generally, the color contrast and the optical switching speed increase drastically if high surface area is used. The structure of porous thin film provides a specific surface area and can facilitate a very short response time of the reaction between the surface and ions. The large variety of methods has been used to prepare the porous NiO thin films such as sol-gel process, chemical bath deposition and sputtering. Few studies have been reported on NiO thin films made by using sol-gel method. However, compared with dry process, wet processes that have the questions of the durability and the vestige of bleached state color limit the thin films practical use, especially when prepared by sol-gel method. In this study, we synthesis the porous NiO thin films on the fluorine doped tin oxide (FTO) glass by using sputtering and anodizing method. Also we compared electrical and optical properties of NiO thin films prepared by sol gel. The porous structure is promised to be helpful to the properties enhancement of the EC devices.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2016년도 추계학술대회 논문집
• /
• pp.153-153
• /
• 2016

Aluminum alloys have poor corrosion resistance compared to the pure aluminum due to the additive elements. Thus, anodizing technology artificially generating thick oxide films are widely applied nowadays in order to improve corrosion resistance. Anodizing is one of the surface modification techniques, which is commercially applicable to a large surface at a low price. However, most studies up to now have focused on its commercialization with hardly any research on the assessment and improvement of the physical characteristics of the anodized films. Therefore, this study aims to select the optimum temperature of sulfuric electrolyte to perform excellent corrosion resistance in the harsh marine environment through electrochemical experiment in the sea water upon generating porous films by variating the temperatures of sulfuric electrolyte. To fabricate uniform porous film of 5083 aluminum alloy, we conducted electro-polishing under the 25 V at $5^{\circ}C$ condition for three minutes using mixed solution of ethanol (95 %) and perchloric (70 %) acid with volume ratio of 4:1. Afterward, the first step surface modification was performed using sulfuric acid as an electrolyte where the electrolyte concentration was maintained at 10 vol.% by using a jacketed beaker. For anode, 5083 aluminum alloy with thickness of 5 mm and size of $2cm{\times}2cm$ was used, while platinum electrode was used for cathode. The distance between the two was maintained at 3 cm. Afterward, the irregular oxide film that was created in the first step surface modification was removed. For the second step surface modification process (identical to the step 1), etching was performed using mixture of chromic acid (1.8 wt.%) and phosphoric acid (6 wt.%) at $60^{\circ}C$ temperature for 30 minutes. Anodic polarization test was performed at scan rate of 2 mV/s up to +3.0 V vs open circuit potential in natural seawater. Surface morphology was compared using 3D analysis microscope to observe the damage behavior. As a result, the case of surface modification presented a significantly lower corrosion current density than that without modification, indicating excellent corrosion resistance.

• Korean Chemical Engineering Research
• /
• 제46권5호
• /
• pp.852-857
• /
• 2008

광촉매의 고정화는 광촉매의 이용범위를 넓히기 위해서 매우 중요한 기술이다. 광촉매를 고정화시키기 위해 티타늄 표면을 양극산화 시켜 $TiO_2$로 전환시킬 수 있다. 양극산화에 의해 제조된 $TiO_2$는 광촉매 활성을 가지고 있으며 표면은 스펀지와 비슷한 형태를 나타내었다. 다양한 초기농도, 습도, 방전전압 하에서 양극산화에 의해 티타니아를 제조 이를 이용하여 기상의 아세트알데히드와 VOC의 광촉매 분해반응을 연구하였다. 양극산화 티타니아의 반응성은 상대습도가 증가함에 따라 증가하였으나 너무 높은 습도는 반응성을 감소시켰다. 광촉매 반응과 전기 방전을 결합시키면 VOC 제거효율이 크게 증가 되었으나, 과도한 전압을 가하여 코로나 방전이 발생되면 반응속도가 오히려 감소되었다. 최적 상대습도는 40%였으며 최적 방전전압은 암방전 영역인 5 kV였다.

• Corrosion Science and Technology
• /
• 제20권2호
• /
• pp.45-51
• /
• 2021

In this work, we describe the effect of pulse anodizing duty ratio on the corrosion resistance of anodic films in magnesium AZ31B. The process involves the application of square pulse potential for a constant period with a duty ratio varying from 40, 60 and 80%. In several samples, a sealing treatment for 30 minutes was conducted after anodization in order to seal the pores available in the anodic layer. After anodizing, the surface morphology of the anodic layer was examined using a scanning electron microscope (SEM Hitachi SU3500). The corrosion characteristics of the sample were evaluated through an open circuit potential (OCP) and potentiodynamic polarization test using potentiogalvanostat. SEM observation shows that the increase of anodization duty ratio (α) results in a more uniform anodic layer, with fewer pores and cracks. The increase of duty ratio (α) decreases the OCP value from approximately -1.475 to about -1.6 Volt, and significantly improves the corrosion resistance of the anodic coating by 68%. The combination of anodization and sealing treatment produces an anodic coating with a very low corrosion rate of 4.4 mpy.

• 반도체디스플레이기술학회지
• /
• 제21권2호
• /
• pp.19-24
• /
• 2022

The purpose of this research is to determine the hardness of guide hole. A guide pin and a guide hole of SSD(Solid State Drive) tester used to mount SSD in a fixed position accurately. The guide pin and guide hole are worn by friction due to repeated operation, and the wear is concentrated on the guide hole made of weak material rather than the guide pin made of relatively strong material. Because of that reason, it is often overdesigned in the design stage because it can lose its function. If the guide hole is made soft, the manufacturing cost will decrease, but the accuracy will decrease due to wear caused by repeated friction. If the guide hole is manufactured excessively, the manufacturing process becomes complicated and the manufacturing cost increases. It is essential to design a guide hole, but since there is no standard or verified data that can be referenced, it is difficult to design. Experimental device which guides in the same way as the SSD tester is used for this research, and three types of anodizing state are experimented for different hardness. Also, weight of COK(Change over Kit) were analyzed by measuring the wear amount and state of the guide hole according to the number of repeated attachment and detachment.

• 대한화학회지
• /
• 제64권3호
• /
• pp.153-158
• /
• 2020

With the recent popularity of mobile devices, the demand for lithium-ion batteries is increasing. In this study, the surface treatment process for the development of the Al (aluminum) lead tab for positive electrode, a key component of the pouch-type lithium-ion battery, was investigated. Anodizing and sealing processes were tested as surface treatment techniques. It was found that only a sealing process is needed to obtain sufficient adhesive strength. In the present study, an adhesive strength of 17 N/12 mm was achieved by degreasing and etching pretreatment, followed by a sealing process of 10 min duration. This adhesive strength was greater than that achievable using Cr (chromium) surface treatment. Using various surface analysis techniques, the shape and composition of the surface before and after being subjected to the surface treatment were compared and analyzed. The results of this study are expected to contribute to the development of an eco-friendly lead tab.

• 한국표면공학회지
• /
• 제22권2호
• /
• pp.62-68
• /
• 1989

Pb2+ ino, added in ctching sohing, is electrodeposited on a alumiunm foil for electrolycic condenser to promote its capacitance. In addition, several factoral factors in etching process are varied to examine how they change the capacitance of the condenser. The capacitance of the condenser made of 0.1 ppm pb electrodeposited aluminum foil is enhanced about 20% than of conventional ane. It is thought out that the enhanement is the result of the act of PbO2, which existed for the conveting of electrodeposited Pb, as a promoter tunnel etching of aluminum foil.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• 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.