• 한국표면공학회지
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• 제53권5호
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• pp.257-264
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• 2020

Anodization of Fe and Fe alloys is one of the most promising techniques to obtain iron oxide films applying to the various electrochemical devices due to their electrochemical catalytic properties. In this study, we investigate on the preparation of anodic iron oxide composite incorporated with WO₃ through a single-step anodization of stainless steel type-304 (STS304) as a substrate. The effects of applied voltage and tungsten precursor on the structural characteristics of iron oxide composite with different amount of incorporated WO₃ were observed. It is demonstrated that when the voltage of 60 V applied with 20 mM of Na₂WO₄ as a precursor, anodic iron oxide composite with a large pore diameter and a thick oxide length in which WO₃ is uniformly incorporated is obtained.

• 대한금속재료학회지
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• 제46권6호
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• pp.370-376
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• 2008

The formation of anodic oxide film of titanium (Ti) was studied at a variety of electrolyte concentrations and current density to clarify their effects on morphology, microstructure and composition of Ti oxide layer. For the analysis of the Ti oxide films, a scanning electron microscopy (SEM), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS) were used. The results showed that the concentration of phosphoric acid played a crucial role in the crystalline structure of the Ti oxide layer while the current density gave a critical effect on the thickness and diameter of its pore. In particular, the crystalline anatase phase with a thickness larger than $2{\mu}m$, which is quite desirable for a dental implant application, could be readily prepared at the phosphoric acid concentration of 0.5 M and current density higher than $2.0A/dm^2$.

• 대한기계학회논문집A
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• 제37권5호
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• pp.625-630
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• 2013

본 연구는 직경 45 nm인 원통형 나노동공을 가진 산화알루미늄(AAO) 박막에 오일을 함침시켰을때 동점도가 마찰 마멸에 미치는 영향을 규명하고자 실시하였다. 양극산화법으로 제조한 AAO 박막을 직경 1 mm의 440C 스테인리스 강구를 상대재로 하여 왕복동 미끄럼 접촉시험을 실시하였다. 마찰면과 마멸입자는 주사전자현미경과 에닥스(Energy-dispersive X-ray)를 이용해 분석하였다. 높은 동점도 오일의 윤활효과가 저점도 오일에 비해 크게 향상되었다. 동점도가 낮은 경우엔 모든 하중조건에서 심한 마찰흔적과 함께 두꺼운 소성변형층이 넓게 형성되었으며 경계윤활막의 손상으로 접촉면에 물질전이와 화학적 반응 현상이 모두 발생하였다. 오일의 점도가 높은 경우 마찰면에 존재하는 경계윤활막이 파괴되지 않아 마찰흔적과 소성변형층의 형성이 매우 적었으며 물질전이와 화학적 반응이 방지되었다.

• 구강회복응용과학지
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• 제24권4호
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• pp.361-369
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• 2008

본 연구의 목적은 다공성의 티타늄 산화막에 불소를 처리한 결과를 평가하는 것이다. 디스크에 양극산화법을 통하여 다공성의 티타늄산화막표면을 얻은 후 불소를 처리하고 일정시간동안 Hank액에 침전을 시켰다. 양극산화를 통해 일정거칠기의 표면을 얻었으며 SEM과 XRD를 통하여 표면의 형상과 성분을 분석하였다. 생성된 표면은 빠른 표면 활성도를 보였으며, 적절한 거칠기와 좋은 골반응으로 골유착에 기여할 수 있을 것으로 여겨진다.

• Corrosion Science and Technology
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• 제16권6호
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• pp.317-327
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• 2017

The change in the oxidation behavior of three types of B-added ultrahigh strength martensitic steels containing Ti and Nb induced by applying constant cathodic current was investigated. In a 3% NaCl+0.3% $NH_4SCN$ solution, the overall polarization behavior of the three alloys was similar, and degradation of the oxide film was observed in the three alloys after applying constant cathodic current. A significant increase in the anodic current density was observed in the Nb-added alloy, while it was diminished in the Ti-added alloy. Both Ti and Nb alloying decreased the hydrogen overpotential by forming NbC and TiC particles. In addition, the thickest oxide film was formed on the Ti-added alloy, but the addition of Nb decreased the film thickness. Therefore, it was concluded that the remarkable increase in the anodic current density of Nb-added alloy induced by applying constant cathodic current density was attributed to the formation of the thinnest oxide film less protective to hydrogen absorption, and the addition of Ti effectively blocked the hydrogen absorption by forming TiC particles and a relatively thick oxide film.

• 한국재료학회지
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• 제14권2호
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• pp.133-140
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• 2004

We carried out anodic aluminum oxide (AAO) on a Si and a sapphire substrate. For anodic oxidation of Al two types of specimens prepared were Al(0.5 $\mu\textrm{m}$)!Si and Al(0.5 $\mu\textrm{m}$)/Ti(0.1 $\mu\textrm{m}$)$SiO_2$(0.1 $\mu\textrm{m}$)/GaN(2 $\mu\textrm{m}$)/Sapphire. Surface morphology of Al film was analyzed depending on the deposition methods such as sputtering, thermal evaporation, and electron beam evaporation. Without conventional electron lithography, we obtained ordered nano-pattern of porous alumina by in- situ process. Electropolishing of Al layer was carried out to improve the surface morphology and evaluated. Two step anodizing was adopted for ordered regular array of AAO formation. The applied electric voltage was 40 V and oxalic acid was used as an electrolyte. The reference electrode was graphite. Through the optimization of process parameters such as electrolyte concentration, temperature, and process time, a regular array of AAO was formed on Si and sapphire substrate. In case of Si substrate the diameter of pore and distance between pores was 50 and 100 nm, respectively. In case of sapphire substrate, the diameter of pore and distance between pores was 40 and 80 nm, respectively

• Corrosion Science and Technology
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• 제14권6호
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• pp.261-266
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• 2015

The capacity of passive metal to repassivate after film damage determines the development of local corrosion and the resistance to corrosion failures. In this work, the repassivation kinetics of 316L stainless steel (316L SS) was investigated in borate buffer solution (pH 9.1) using a novel abrading electrode technique. The repassivation kinetics was analyzed in terms of the current density flowing from freshly bare 316L SS surface as measured by a potentiostatic method. During the early phase of decay (t < 2 s), according to the Avrami kinetics-based film growth model, the transient current was separated into anodic dissolution ($i_{diss}$) and film formation ($i_{film}$) components and analyzed individually. The film reformation rate and thickness were compared according to applied potential. Anodic dissolution initially dominated the repassivation for a short time, and the amount of dissolution increased with increasing applied potential in the passive region. Film growth at higher potentials occurred more rapidly compared to at lower potentials. Increasing the applied potential from 0 $V_{SCE}$ to 0.8 $V_{SCE}$ resulted in a thicker passive film (0.12 to 0.52 nm). If the oxide monolayer covered the entire bare surface (${\theta}=1$), the electric field strength through the thin passive film reached $1.6{\times}10^7V/cm$.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 춘계학술발표회 초록집
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• pp.60-60
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• 2001

• 대한치주과학회:학술대회논문집
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• 대한치주과학회 2001년도 제41회 종합학술대회 연제초록
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• pp.37-38
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• 2001

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 춘계학술발표회 초록집
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• pp.69-70
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• 1999