마그네슘 합금 안경테의 Plasma Electrolytic Oxidation표면처리 효과 연구

김기홍 한국안광학회 2010 한국안광학회지 Vol.15 No.4

Purpose: The purpose of this study was to investigate the surface characteristics of plasma electrolytic oxidation (PEO) surface treatment on AZ31 magnesium alloy eyeglass frames. Methods: The plasma electrolytic oxidation (PEO) surface was created by varying the DC voltage. The oxidation layer of coating was measured using phase analysis by X-ray diffraction. The microstructural morphology was observed using a scanning electron microscopy. Coating layer and the concentration of elements were investigated using the energy dispersive X-ray spectra. Results: The MgO XRD peak was increased as the voltage increased, and the density of the surface oxide film was also increased. The changes in the composition of the EDS also showed a good agreement. Conclusions: The compound oxide crystallization of PEO oxide film layer was done by increasing formation of MgO as the voltage increased. The treatment at 65V and 60 sec showed the best results at surface state, contact angles and salt spray test. 목적: 이 연구 목적은 가공한 마그네슘 합금 AZ31 안경테를 plasma electrolytic oxidation(PEO) 표면 처리 후 표 면특성에 대하여 조사하는 것이다. 방법: Plasma electrolytic oxidation(PEO) 표면 처리는 DC 전압을 변화시키며 처 리하였고, 피막의 상 분석은 X-ray 회절기로 측정하였고, 형태학적 미세구조는 주사전자현미경로 관찰하였다. 그리 고 피막층에 존재하는 원소의 농도를 에너지 분산 X-선 스펙트럼으로 조사하였다. 결과: PEO 처리시 전압이 증가 함에 따라 XRD 측정 결과 MgO 피크가 증가하였으며, SEM 사진에서는 표면의 산화피막이 조밀하게 생기는 것을 확인 할 수 있었다. 그리고 EDS에서 성분의 변화도 일치함을 보여주었다. 결론: PEO 산화피막층은 전압이 증가 할 수록 MgO 화합물의 형성이 점점 증가하기 때문에 산화막의 결정화가 진행되며, 65V에 60초 처리 시 표면상태, 접 촉각, 내식성 시험에서 가장 좋은 결과를 보여 주었다.

Characterization of Ceramic Oxide Layer Produced on Commercial Al Alloy by Plasma Electrolytic Oxidation in Various KOH Concentrations

Jung-Hyung Lee,Seong-Jong Kim 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2

Plasma electrolytic oxidation (PEO) is a promising coating process to produce ceramic oxide on valve metals such as Al, Mg and Ti. The PEO coating is carried out with a dilute alkaline electrolyte solution using a similar technique to conventional anodizing. The coating process involves multiple process parameters which can influence the surface properties of the resultant coating, including power mode, electrolyte solution, substrate, and process time. In this study, ceramic oxide coatings were prepared on commercial Al alloy in electrolytes with different KOH concentrations (0.5 ~ 4 g/L) by plasma electrolytic oxidation. Microstructural and electrochemical characterization were conducted to investigate the effects of electrolyte concentration on the microstructure and electrochemical characteristics of PEO coating. It was revealed that KOH concentration exert a great influence not only on voltage-time responses during PEO process but also on surface morphology of the coating. In the voltage-time response, the dielectric breakdown voltage tended to decrease with increasing KOH concentration, possibly due to difference in solution conductivity. The surface morphology was pancake-like with lower KOH concentration, while a mixed form of reticulate and pancake structures was observed for higher KOH concentration. The KOH concentration was found to have little effect on the electrochemical characteristics of coating, although PEO treatment improved the corrosion resistance of the substrate material significantly.

Plasma Electrolytic Oxidation in Surface Modification of Metals for Electronics

정재필 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.3

This paper presents a brief summary on a relatively new plasma aided electrolytic surface treatmentprocess for light metals. A brief discussion regarding the advantages, principle, process parameters andapplications of this process is discussed. The process owes its origin to Sluginov who discovered an arcdischarge phenomenon in electrolysis in 1880. A similar process was studied and developed by Markovand coworkers in 1970s who successfully deposited an oxide film on aluminium. Several investigationthereafter lead to the establishment of suitable process parameters for deposition of a crystalline oxide filmof more than 100μm thickness on the surface of light metals such as aluminium, titanium and magnesium. This process nowadays goes by several names such as plasma electrolytic oxidation (PEO), micro-arcoxidation (MOA), anodic spark deposition (ASD) etc. Several startups and surface treatment companieshave taken up the process and deployed it successfully in a range of products, from military grade riflesto common off road sprockets. However, there are certain limitations to this technology such as theformation of an outer porous oxide layer, especially in case of magnesium which displays a PilingBedworth ratio of less than one and thus an inherent non protective oxide. This can be treated further butadds to the cost of the process. Overall, it can be said the PEO process offers a better solution than theconventional coating processes. It offers advantages considering the fact that he electrolyte used in PEOprocess is environmental friendly and the temperature control is not as strict as in case of other surfacetreatment processes.

Anodic Oxide Films Formed on AZ31 Magnesium Alloy by Plasma Electrolytic Oxidation Method in Electrolytes Containing Various NaF Concentrations

Sungmo Moon,Duyoung Kwon 한국표면공학회 2016 한국표면공학회지 Vol.49 No.3

The present work was conducted to investigate the effects of NaF concentration in phosphate and silicate-containing alkaline electrolyte on the morphology, thickness, surface roughness and hardness of anodic oxide films formed on AZ31 Mg alloy by plasma electrolytic oxidation (PEO) method. The PEO films showed flat surface morphology with pores in the absence of NaF in the electrolyte, but nodular features appeared on the PEO film surface prepared in NaF-containing electrolyte. Numerous pores ranging from 1 to 20 μm in size were observed in the PEO films and the size of pores decreased with increasing NaF concentration in the electrolyte. Surface roughness and thickness of PEO films showed increases with increasing NaF concentration. Hardness of the PEO films also increased with increasing NaF concentration. It was noticed that hardness of inner part of the PEO films is lower than that of outer part of them, irrespective of the concentration of NaF. The low hardness of PEO films was explained by the presence of a number of small size pores less than 2 μm near the PEO film/substrate interface.

Surface Characteristics of Dental Implant Doped with Si, Mg, Ca, and P Ions via Plasma Electrolytic Oxidation

박선영,최한철 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.4

The surface characteristics of a dental implant doped with Si, Mg, Ca, and P ions via plasma electrolytic oxidation (PEO) were investigated using various experimental instruments. Plasma electrolytic oxidation of the alloy was performed in a solution containing Ca, P, Si, and Mg ions at 280 V for 3 min. The potentiodynamic polarization test of the porous surface was conducted in a 0.9% NaCl solution. The Si and Mg ion-doped HA films exhibited small and large micro-pores with uniform distributions after the PEO treatment. The micro-pores formed on the 5~20Mg/5Si coated samples were smaller than those on the Si and Mg ion-free CaP coated surfaces, as the Mg ion concentration increased. The XRD peaks of Si, Mg, Ca, and P appeared and the Si, Mg, Ca, and P were well distributed on the PEO-treated surface, especially on the top, valley and crest of the screw. The Ca/P ratio decreased as Mg content increased in the electrolyte. The diffraction peak of anatase TiO2 was observed on the Si and Mg ion HA film formed on the Ti-6Al-4V alloy. The adhesion force of the Si and Mg doped HA films increased with increasing Mg and Si ion concentrations. A passive region due to passive film formation was observed. The HA film surface with Si and Mg ions showed lower Ecorr and higher Icorr compared to the HA film surface without Si and Mg ions. And the Ipp and I300 for 5~20Mg/5Si formed on the Ti-6Al-4V alloy were lower than those of the surface coated with HA without Si and Mg ions.

Influence of the Duty Cycle on Structural and Mechanical Properties of Oxide Layers on Al-1050 by a Plasma Electrolytic Oxidation Process

Jeong-Hwan Song,Kyung-Su Nam,Jung-In Moon,Young-Jun Choi,Dae-Young Lim 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.3

Oxide layers were prepared on Al-1050 substrates by an environmentally friendly plasma electrolytic oxidationprocess using an alkaline solution of Na2SiO3 (8 g/L) and NaOH (3 g/L) as the electrolyte. The effects of threedifferent duty cycles (20%, 40%, and 60%) on the structure and hardness of the oxides were investigated. XRD analysis revealed that the oxides were mainly composed of α-Al2O3, γ-Al2O3, and mullite. The proportionof each phase depended on various electrical parameters, such as the duty cycle and frequency. Themorphology, thickness, and the elemental distribution of the oxides were examined by scanning electronmicroscopy and energy dispersive spectroscopy. The thicknesses of the oxides were found to vary from 20 μmto more than 60 μm for various duty cycles, when identical treatment durations were used. The oxidationtreatment also resulted in good adhesion between the oxide layer and the substrate. SEM images indicatedthat the oxide layers formed at the 60% duty cycle exhibited relatively coarser surfaces with larger poresizes and sintering particles, and slower growth rates than did those formed at the 20% duty cycle, under identicaltreatment durations. The oxides prepared at the 20% duty cycle showed smooth surfaces. The oxides layerswere found to improve the micro-hardness of Al-1050. In particular, the oxide layers formed at the 40%duty cycle exhibited relatively better micro-hardness owing to their compact microstructures.

Plasma Electrolytic Oxidation in Surface Modification of Metals for Electronics

Sharma, Mukesh Kumar,Jang, Youngjoo,Kim, Jongmin,Kim, Hyungtae,Jung, Jae Pil The Korean Welding and Joining Society 2014 대한용접·접합학회지 Vol.32 No.3

This paper presents a brief summary on a relatively new plasma aided electrolytic surface treatment process for light metals. A brief discussion regarding the advantages, principle, process parameters and applications of this process is discussed. The process owes its origin to Sluginov who discovered an arc discharge phenomenon in electrolysis in 1880. A similar process was studied and developed by Markov and coworkers in 1970s who successfully deposited an oxide film on aluminium. Several investigation thereafter lead to the establishment of suitable process parameters for deposition of a crystalline oxide film of more than $100{\mu}m$ thickness on the surface of light metals such as aluminium, titanium and magnesium. This process nowadays goes by several names such as plasma electrolytic oxidation (PEO), micro-arc oxidation (MOA), anodic spark deposition (ASD) etc. Several startups and surface treatment companies have taken up the process and deployed it successfully in a range of products, from military grade rifles to common off road sprockets. However, there are certain limitations to this technology such as the formation of an outer porous oxide layer, especially in case of magnesium which displays a Piling Bedworth ratio of less than one and thus an inherent non protective oxide. This can be treated further but adds to the cost of the process. Overall, it can be said the PEO process offers a better solution than the conventional coating processes. It offers advantages considering the fact that he electrolyte used in PEO process is environmental friendly and the temperature control is not as strict as in case of other surface treatment processes.

Corrosion Resistance of Plasma-Anodized AZ91 Mg Alloy in the Electrolyte with/without Potassium Fluoride

Hwang, Duck Y.,Kim, Yong M.,Shin, Dong H. The Japan Institute of Metals 2009 MATERIALS TRANSACTIONS Vol.50 No.3

<P>Plasma Electrolyte Oxidation (PEO) behavior of AZ91 Mg alloy was investigated in the electrolytes with/without potassium fluoride. Growth rate of coating thickness in the electrolyte containing potassium fluoride (Bath B) was much higher than that in the electrolyte without potassium fluoride (Bath A). The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium fluoride and sodium silicate consisted of MgO, MgF<SUB>2</SUB> and Mg<SUB>2</SUB>SiO<SUB>4</SUB>. Corrosion current density of oxide layer coated from the electrolyte with potassium fluoride was much lower than that of oxide layer coated from the electrolyte without potassium fluoride. From the result of EIS analysis, it was known that inner barrier layer in the oxide layer coated from the electrolyte with potassium fluoride had a good influence of the corrosion resistance of Mg alloy. The corrosion resistance curves of Bath B were similar to the thickness curves, indicating that the thickness of the oxide layer played an important role in corrosion resistance of AZ91 Mg alloy. The oxide layer in the Bath B containing potassium fluoride was found to be a compact barrier-type passive film in presence of fluoride ions. The existence of the dense MgO and MgF<SUB>2</SUB> in the barrier layer had a favorable effect on the corrosion resistance of the AZ91 Mg alloy formed from Bath B by PEO process.</P>

Characteristics of Oxide Layers Formed on Al2021 Alloys by Plasma Electrolytic Oxidation in Aluminate Fluorosilicate Electrolyte

Kai Wang,Bon Heun Koo,Chan Gyu Lee,Young Joo Kim,Sunghun Lee,Eungsun Byon 한국표면공학회 2008 한국표면공학회지 Vol.41 No.6

Oxide layers were prepared on Al2021 alloys substrate under a hybrid voltage of AC 200 V (60 ㎐) combined with DC 260 V value at room temperature within 5~60 min by plasma electrolytic oxidation (PEO). An optimized aluminate-fluorosilicate solution was used as the electrolytes. The surface morphology, thickness and composition of layers on Al2021 alloys at different reaction times were studied. The results showed that it is possible to generate oxide layers of good properties on Al2021 alloys in aluminate-fluorosilicate electrolytes. Analysis show that the double-layer structure oxide layers consist of different states such as α-Al₂O₃ and γ-Al₂O₃. For short treatment times, the formation process of oxide layers follows a linear kinetics, while for longer times the formation process slows down and becomes a steady stage. During the PEO processes, the average size of the discharge channels increased gradually as the PEO treatment time increased.

Preparation of PEO ceramic coating on Ti alloy and its high temperature oxidation resistance

Yongjun Xu,Zhongping Yao,Fangzhou Jia,Yunlong Wang,Zhaohua Jiang,Haitao Bu 한국물리학회 2010 Current Applied Physics Vol.10 No.2

Ceramic coatings were prepared in Na2SiO3–Na2CO3–NaOH system by pulsed bi-polar plasma electrolytic oxidation on Ti–6Al–4V alloy. The phase composition, structure and the elemental distribution of the coatings were studied by XRD, SEM and energy dispersive spectroscopy, respectively. The thermal shock resistance of the coated samples at 850 ℃ was evaluated by the thermal shock tests. The high temperature oxidation resistance of the coating samples at 500 ℃ was investigated. The results showed that the coating was mainly composed of rutile- and anatase TiO2, Increasing the concentration of Na2SiO3, TiO2content decreased gradually while the thickness of the coating increased. There were a large amount of micro pores and sintered particles on the surface of the coatings. Increasing concentration of Na2SiO3, the sintered particles on the surface turned large, and the Si content increased while the Ti content decreased gradually. When the concentration of Na2SiO3 was 15 g/L, the thermal shock resistance of the coatings was better than that of the coatings that prepared under other Na2SiO3 concentrations. The coating samples prepared under the optimized technique process based on the thermal shock tests improved the high temperature oxidation resistance at 500 ℃ greatly, whether considering the isothermal oxidation or the cyclic oxidation.