• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.128-129
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• 2013

Plasma 공정 부품의 경우, 기존 Anodizing 제품의 문제점을 개선하기 위해, 내마모, 내부식 특성이 우수한 NiWP를 적용하였다. 합금도금 종류에 따라 NiWP, NiWPB, NiWPS Electreolss laeyr 형성 후에 내부식 특성 거동 분석을 실시하였다. 그 결과 NiWP Electreoless layer가 높은 내부식 특성을 보였다.

• 한국표면공학회지
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• 제35권6호
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• pp.401-407
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• 2002

Most of organic compounds discharged from industrial wastewater are treated by chemical oxidation, adsorption and biodegradable process. This process has been demanded a new advanced environmental wastewater treatment process. From this point of view, an electrochemical oxidation process using electrocatalysts has been developed for the destruction of organic compounds. Through this study, a ruthenium oxide/iridium oxide supported on titanium expanded metal was fabricated by thermal decomposition method and its performance was excellent during this experiment.

• 접착 및 계면
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• 제5권2호
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• pp.1-7
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• 2004

A novel carboxyl terminated butadiene-acrylonitrile (CTBN) modified, low temperature cure epoxy film adhesive was developed in this paper. It can be cured at as low as $75^{\circ}C$ for 4 hours with a pressure of 0.1MPa. After post cure at $120^{\circ}C$ for 2 hours, the bonding strengths of Phosphoric Acid Anodizing(PAA) surface treated aluminum adherend were similar to those of structural film adhesives curing at $120^{\circ}C$. It is suitable to bond both metal/composite laminate-to-laminate and laminate to honeycomb structure.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2008년도 추계학술대회 초록집
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• pp.32-32
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• 2008

생체용 티타늄 합금은 높은 내식성 및 생체적합성을 갖는 특성으로 치과용 임플란트 및 인공 고관절 분야에서 널리 쓰이고 있다. 본 연구에서는 Ti에 Hf 원소를 10, 20, 30 및 40 % 첨가하여 합금 한 후, 양극산화 처리를 통해 다공성 산화피막을 형성하였다. 각각 다른 온도에서 열처리 한 후, 인가전압, Hf 원소 함량 및 열처리 온도에 따른 부식특성을 조사하였다.

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

• 한국재료학회지
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• 제17권1호
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• pp.6-10
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• 2007

In the present study, we investigated the formation of self-organized nanostructure oxide layers on CP Ti and Ti-10Ta-10Nb alloy in an electrolyte of 1M phosphoric acid and 1.5 wt% Hydrofluoric acid. The morphology of oxide film on substrate was observed using scanning electron microscopy and transmission electron microscopy The surface roughness of titanium oxide film was analyzed by atomic force microscopy and the crystalline of specimen was investigated using X-ray diffractometer. The results of this study showed that well-aligned titanium oxide nanotubes are formed with diameter of approx. 100nm and length of approx. 500nm with CP Ti. However, it is clear that TiTaNb alloy highly irregular structure with various diameters. Transmission electron microscope investigations show that the specimens were confirmed as amorphous. Such titanium oxide nanotubes are expected a well-adhered bioacitive surface layer on titanium substrate for orthopedics and dental implants.

• 한국결정성장학회지
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• 제25권3호
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• pp.98-104
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• 2015

Titanium barrier membranes are prepared to investigate the effect of surface-treatments, such as machining, electropolishing, anodizing, and electropolishing + TiN coating, on the biocompatibility and physical properties of the membranes. The surface roughness (Ra) of the membrane decreases from machining ($0.37{\pm}0.09{\mu}m$), TiN coating ($0.22{\pm}0.09{\mu}m$), electropolishing ($0.20{\pm}0.03{\mu}m$), to anodizing ($0.15{\pm}0.03{\mu}m$). The highest ductility (24.50 %) is observed for the electropolished Ti membrane. No evidence of causing cell lysis or toxicity is found for the membranes regardless of the surface-treatments. Cell adhesion results of L-929 and MG-63 show that the machined Ti membrane exhibits the highest cell adhesion while the electropolished membrane is the best membrane for the L-929 cell proliferation after 7 days. However, no appreciable difference in MG-63 cell proliferation among variously surface-treated membranes is detected, suggesting that the electropolished Ti membrane is likely to be the best membrane due to the synergic combination of tailored flexibility and excellent fibroblast proliferation.

• Corrosion Science and Technology
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• 제16권5호
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• pp.257-264
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• 2017

Film of new Ti-15Zr-5Nb alloy formed during galvanic anodizing in orthophosphoric acid solution was characterized by optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Raman micro-spectroscopy. Its anticorrosive properties were determined by electrochemical techniques. The film had a layer with nanotube-like porosity with diameters in 500-1000 nm range. The nano layer contained significant amounts of P and O as well as alloying element. Additionally, Raman micro-spectroscopy identified oxygen as oxygen ion in $TiO_2$ anatase and phosphorous as $P_2O_7{^{4-}}$ ion in phosphotitanate compound. All potentiodynamic polarization curves in artificial Carter-Brugirard saliva with pH values (pH= 3.96, 7.84, and 9.11) depending on the addition of 0.05M NaF revealed nobler behavior of anodized alloy and higher polarization resistance indicating the film is thicker and more compact nanolayer. Lower corrosion rates of the anodized alloy reduced toxicity due to less released ions into saliva. Bigger curvature radii in Nyquist plot and higher phase angle in Bode plot for the anodized alloy ascertain a thicker, more protective, insulating nanolayer existing on the anodized alloy. Additionally, ESI results indicate anodized film consists of an inner, compact, barrier, layer and an outer, less protective, porous layer.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.149-149
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• 2017

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 seawater 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. 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 showed a significantly lower corrosion current density than that without modification, indicating excellent corrosion resistance.

• Tribology and Lubricants
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• 제33권2호
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• pp.59-64
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• 2017

This study investigates friction and wear characteristics of anodized aluminum (Al) alloy 6061 by using a reciprocating tribotester. The diameter and height of the specimen are 30 mm and 10 mm, respectively. The surface roughness of the mirrored-surface is approximately $0.01{\sim}0.02{\mu}m$, and it is used throughout the current study. As a result of anodizing, the depth and diameter of the nanopore are approximately $25{\mu}m$ and 30-40 nm, respectively. The testing conditions are as follows: loads of 1, 3, and 5 N; a frequency of 1 Hz; a stoke of 3 mm; and a duration of 1800 s. We use deionized water with a volume of approximately $25{\mu}l$, as the lubricant. Micro Vickers hardness measurements show that mirrored-surface specimens had lower hardness values than anodized specimens. Further, their coefficients of friction are lower than those of the anodized samples, and the width of their wear track increases with load, as expected. The anodized specimens' coefficients of friction increase with stable frictional behavior and exhibit insignificant load dependence. Further, we observe that the width of the wear track is less than that of the mirrored-surface specimens, and micro cracks are present near it. Moreover, the anodizing process increases the hardness of the samples, improving their wear resistance. These results indicate that nanoporous structures are not effective in lowering friction under the water-lubricated condition.