• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.191.1-191.1
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• 2016

본 연구에서는 알루미늄 합금의 PEO(Plasma Electrolytic Oxidation) 피막 형성 거동을 PEO 처리 용액 조성, 온도 및 합금 성분에 따른 전압-시간 곡선을 관찰하여 분석하였다. 알루미늄 합금의 PEO 피막 형성거동은 NaOH 농도, 전해질 온도, 인가 전류밀도 및 합금성분에 따라 다양하게 나타났다. 본 연구에서는 직류 정전류법을 이용하여 Al1050, Al5052, Al6061 합금 표면에 PEO 피막을 형성시켰으며, PEO 피막의 형성이 시작되는 전압 및 발생된 아크의 크기 및 모양을 관찰하여 PEO 피막 형성 거동을 연구하였다. 연구결과 PEO 처리 중의 전해액의 온도가 낮고 전류밀도가 높을수록 시편 표면에서 짧은 시간 내에 아크가 발생하였으며, 전압-시간 곡선은 빠른 속도로 PEO 피막생성 전압에 도달하여 유지되는 거동을 보였다. 동일한 용액조성, 용액온도, 용액 교반속도 및 인가전류밀도에서 관찰된 PEO 피막 형성 거동은 동일시편을 PEO코팅 후 에칭하여 반복 실험할 경우에도 큰 편차를 보였으며, 이로부터 시편의 조성이나 불순물의 존재 등이 크게 영향을 주는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.115.2-115.2
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• 2016

Al alloys are being used widely for automobile, aerospace and mechanical components because of their high strength ratio to weight. However, still they suffer from abrasion or corrosion owing to insufficient resistances to friction or mechanical impact and chemical attack. Plasma electrolytic oxidation (PEO) method is one of the promising surface treatment methods for Al alloys which can render better hardness than aluminum anodic oxide (AAO) films prepared by conventional anodizing method in acidic solutions. In this presentation, some basic nature of PEO film formation and growth process on Al alloys will be presented based on the experimental results obtained and discussed in view of dielectric breakdown and reformation and the role of various anions in film breakdown and reformation of PEO films.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.8-11
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• 2010

During PEO (plasma-electrolytic-oxidation) treatment of titanium, the relationship between the thickness of oxide film and the measured electrical information was investigated. A simple real time monitoring method based on the electrical information being gathered during PEO treatment is proposed. The proposed method utilizes the current flowing from a high frequency voltage source to calculate the resistance of an oxide film, which is converted into the thickness of an oxide film. This monitoring method can be implemented in PEO system in which an oxide film is grown by constant or pulsed voltage/current sources.

• Journal of the Korean institute of surface engineering
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• v.55 no.1
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• pp.9-17
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• 2022

This work is concerned with the formation behavior of PEO (Plasma Electrolytic Oxidation) films on Al6082 alloy under the application of direct current (DC) and alternating current (AC) in an alkaline solution. Arc initiation voltage became much lower by the application of AC than DC, and arc initiation time became shorter under DC than AC. The number of pores present in the PEO films was much larger than that on the surface, irrespective of DC and AC. It was also found that the number of pores in the PEO films formed under AC was more than that under DC and the size of pores is smaller under AC than DC. During the formation of PEO films, a lot of heat was generated and solution temperature increased more rapidly under DC than under AC which is attributed to high PEO film formation voltage under DC than AC.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.292-298
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• 2022

In this study, PEO (plasma electrolytic oxidation) film formation behavior of AZ31 Mg alloy under application of 300 Hz pulse current was studied by the analyses of V-t curve, arc generation behavior, PEO film thickness and morphology of PEO films with treatment time in 0.05 M NaOH + 0.05 M Na₂SiO₃ + 0.1 M NaF solution. PEO films was observed to grow after 10 s of application of pulse current together with generation of micro-arcs. PEO film grew linearly with treatment time at a growth rate of about 5.58 ㎛/min at 200 mA/cm² of pulse current but increasing rate of film formation voltage became lowered largely with increasing treatment time after passing about 250 V, suggesting that resistivity of PEO films during micro-arc generation decreases with increasing film formation voltage at more than 250 V.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.320-321
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• 2012

본 연구에서는 마그네슘 합금의 내식성을 향상시키기 위하여 플라즈마전해산화 (Plasma Electrolytic Oxidation, PEO) 처리를 하였다. PEO 피막 형성 조건으로는 전류밀도, 전해질의 종류 및 합금성분을 변수로 하였으며, 형성된 PEO 피막의 구조, 경도 및 내식성을 평가하여 PEO피막의 특성과 표면 및 단면 구조를 관찰하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.79-79
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• 2017

Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.98.1-98.1
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• 2017

본 연구에서는 정전류 조건에서 알루미늄 합금의 PEO(Plasma Electrolytic Oxidation) 피막 형성 거동에 대한 전해질 조성의 영향을 아크 발생 양상, 전압-시간 곡선 및 형성된 표면피막의 구조를 관찰하여 연구하였다. 실험에 사용된 전해질은 NaOH 수용액에 $Na_2SiO_3$을 혼합하여 구성되었으며, NaOH와 $Na_2SiO_3$의 농도는 각각 0.01 ~ 1.0 M 와 0 ~ 2.0 M 사이로 조절되었다. 0.01 M NaOH 이하의 용액에서는 양극전압이 500 V 이상으로 상승되고 미세한 아크가 시편 표면 전체에 발생했으나, 0.02 M NaOH 이상의 농도에서는 양극전압이 300 V 이하로 감소되었고 아크발생이 관찰되지 않았다. 아크발생이 일어나지 않는 고농도의 0.5 M NaOH 용액의 경우 0.1 M 이상의 $Na_2SiO_3$를 첨가하였을 때 작은 아크의 무리가 발생되었다. 0.5 M NaOH 수용액에 0.1 M ~ 0.2 M $Na_2SiO_3$가 첨가되었을 땐 아크 무리가 발생하나 이내 일부 영역에서만 반복적으로 아크가 발생하는 로컬 버닝 현상이 일어났다. 한편 0.5 M NaOH 수용액에 0.5 M 이상의 $Na_2SiO_3$가 첨가되었을 때는 로컬 버닝이 일어나지 않고 전 표면에 걸쳐서 아크 무리가 이동하며 PEO 피막이 형성되었다. 0.01 M NaOH 수용액에서 형성된 PEO 피막의 두께는 처리 시간에 따라 증가하지 않고 $10{\mu}m$ 이하의 낮은 값을 보였다. 반면에 NaOH와 $Na_2SiO_3$ 혼합수용액에서 형성된 피막의 두께는 약 $30{\mu}m$ 이상의 높은 값을 보였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.159-159
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• 2017

Ti-6Al-4V alloy have been used for dental implant because of its excellent biocompatibility, corrosion resistance, and mechanical properties. However, the integration of such implant in bone was not in good condition to achieve improved osseointergraiton. For solving this problem, calcium phosphate (CaP) has been applied as coating materials on Ti alloy implants for hard tissue applications because its chemical similarity to the inorganic component of human bone, capability of conducting bone formation and strong affinity to the surrounding bone tissue. Various metallic elements are known to play an important role in the bone formation and also affect bone mineral characteristics. Especially, Zn is essential for the growth of the human and Zn coating has a major impact on the improvement of corrosion resistance. Plasma electrolytic oxidation (PEO) is a promising technology to produce porous and firmly adherent inorganic Zn containing TiO2(Zn-TiO2)coatings on Ti surface, and the a mount of Zn introduced in to the coatings can be optimized by altering the electrolyte composition. In this study, effect of Zn content on the corrosion behavior of Ti-6Al-4V alloy after plasma electrolytic oxidation were studied by SEM, EDS, XRD, AC impedance, and potentiodynamic polarization test. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67 mV/s and potential range from -1500 mV to +2000 mV. Also, AC impedance was performed at frequencies ranging from 10 MHz to 100 kHz for corrosion resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.120-120
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• 2016

Ti-6Al-4V alloy have been used for dental implant because of its excellent biocompatibility, corrosion resistance, and mechanical properties. However, the integration of such implant in bone was not in good condition to achieve improved osseointergraiton. For solving this problem, calcium phosphate (CaP) has been applied as coating materials on Ti alloy implants for hard tissue applications because its chemical similarity to the inorganic component of human bone, capability of conducting bone formation and strong affinity to the surrounding bone tissue. Various metallic elements, such as strontium (Sr), magnesium (Mg), zinc (Zn), sodium (Na), silicon (Si), silver (Ag), and yttrium (Y) are known to play an important role in the bone formation and also affect bone mineral characteristics, such as crystallinity, degradation behavior, and mechanical properties. Especially, Zn is essential for the growth of the human and Zn coating has a major impact on the improvement of corrosion resistance. Plasma electrolytic oxidation (PEO) is a promising technology to produce porous and firmly adherent inorganic Zn containing $TiO_2(Zn-TiO_2)$coatings on Ti surface, and the a mount of Zn introduced in to the coatings can be optimized by altering the electrolyte composition. In this study, corrosion behavior of Ti-6Al-4V alloy after plasma electrolytic oxidation in solutions containing Ca, P and Zn were studied by scanning electron microscopy (SEM), AC impedance, and potentiodynamic polarization test. A series of $Zn-TiO_2$ coatings are produced on Ti dental implant using PEO, with the substitution degree, respectively, at 0, 5, 10 and 20%. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to +2000mV. Also, AC impedance was performed at frequencies ranging from 10MHz to 100kHz for corrosion resistance.