• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.101-101
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• 2009

진공아크소스의 거대입자 제거를 위하여 이중 굽힘형 자장여과 아크 소스를 제작하였다. 소스의 각 전자석의 역할을 조사하고, 발전 안정화 영역에 대한 연구를 수행하였다. 또한 이중 굽힘 자장여과아크소스의 아크방전전압, 주입가스의 위치, 유량 및 플라즈마 덕트의 전압에 따른 인출 이온빔의 공간적 분포 및와 에너지 분포에 대한 연구를 진행하였다. 압력 0.1 mtorr에서 인출 이온빔의 평균에너지는 45$\sim$50 eV를 나타내었으며, 압력이 증가함에 따라 감소하는 경향을 보였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.367-367
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• 2009

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.370-370
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• 2010

최근 자연모사를 통한 초저마찰 연구가 활발히 진행되고 있으며 리소그라피, 레이져 가공법 등의 다양한 방법을 통해 표면구조 제어가 시도되고 있다. 본 연구에서는 자장여과 아크 플라즈마 이온 소스를 이용한 WC-Co 및 SCM 415 금속소재의 표면구조 형상제어를 통해 저마찰 특성을 시도하였다. 자장여과 아크 소스는 90도 꺽힘형이며 5개의 자장 코일을 통해 아크 음극에서 발생된 고밀도($10^{13}\;cm^{-3}$ 이상) 플라즈마를 표면처리 대상 기판까지 확산시켰다. 공정 압력은 알곤가스 1 mTorr, 아크 방전 전류는 25 A, 플라즈마 수송 덕트 전압은 10 V이다. 기판 전압은 비대칭 펄스 (-80 %/+5 %)로 -600 V에서 -800 V까지 인가되었으며 -600 V 비대칭 펄스 인가시기판으로 입사하는 알곤 이온 전류 밀도는 약 $4.5\;mA/cm^2$ 이다. WC-Co 시편의 경우 -600 V 전압 인가시, 이온빔 처리 전 46.4 nm(${\pm}12.7\;nm$)의 조도를 갖는 시편이 5분, 10분, 20분동안 이온빔 처리함에 따라 72.8 nm(${\pm}3\;nm$), 108.2 nm(${\pm}5.9\;nm$), 257.8 nm(${\pm}24.4\;nm$)의 조도를 나타내었다. SCM415 시편의 경우 -800 V 인가시, 이온빔 처리 전 20.4 nm(${\pm}2.9\;nm$)의 조도를 갖는 시편이 20분동안 이온빔 처리함에 따라 275.1 nm(${\pm}43\;nm$)의 조도를 나타내었다. 또한 주사전자현미경을 통한 표면 형상 관찰 결과, 이온빔 식각을 통해 생성된 거친 표면에 $3-5\;{\mu}m$ 직경의 돌기들이 산발적으로 생성됨을 확인했다. 마찰계수 측정 결과 SCM415 시편의 경우, 이온빔 처리전 마찰계수 0.65에서 조도 275.1 nm 시편의 경우 0.48로 감소하였다. 본 연구를 통해 이온빔 식각을 이용한 금속표면 제어 및 저마찰 특성 향상의 가능성을 확인하였다.

• Tribology and Lubricants
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• v.38 no.3
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• pp.101-108
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• 2022

The structure and properties of tetrahedral amorphous carbon (ta-C) coatings depend on the main process parameters and bending angles of the magnetic field filter used in the filtered cathodic vacuum arc (FCVA). During the process, it is possible to effectively control the plasma flux of carbon ions incident on the substrate by controlling the arc discharge current, thereby influencing the mechanical properties of the coating film. Furthermore, we can control the size and amount of large particles mixed during carbon film formation while conforming with the bending angle of the mechanical filter mounted on the FCVA; therefore, it also influences the mechanical properties. In this study, we consider tribological characteristics for filtered bending angles of 45° and 90° as a function of arc discharge currents of 60 and 100 A, respectively. Experiment results indicate that the frictional behavior of the ta-C coating film is independent of the bending angle of the filter. However, its sliding wear behavior significantly changes according to the bending angle of the FCVA filter, unlike the effect of the discharge current. Further, upon changing the bending angle from 45° to 90°, abrasive wear gets accelerated, thereby changing the size and mixing amount of macro particles inside the coating film.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.431-439
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• 2001

In this paper, the a-Diamond films were synthesized using filtered vacuum arc source (FVAS), FVAS was composed of a torus structure with bending angle of 60 degree. The radius of torus was 266 mm, the radius of plasma duct was 80 mm and the total length was 600 mm. The magnet parts were composed of one permanent magnet and five solenoid magnets. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The baffles inside plasma duct were installed in order to prevent the recoil effect of macro-particles. Cathode was made of graphite with 80 mm in diameter. The effects of solenoid magnet on plasma extraction were investigated by computer simulation and experiment using Taguchi's methode. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with low value of the source magnet current and high value of the filtering magnet current. The beam current density was 3.2 mA/$\textrm{cm}^2$ and average deposition rate was 5 $\AA$/sec when the currents of arc discharge, source, extraction, bending, deflection and outlet magnet were 30 A, 1 A, 3 A, 5 A, 5 A, and 5 A, respectively. The beam current density and the efficiency of beam transportation were increased with the positive bias voltage of the plasma duct.

• Tribology and Lubricants
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• v.35 no.6
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• pp.362-368
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• 2019

In this study, mechanical and tribological properties were investigated by varying the process temperature (50, 100, 125 and 150℃) to reduce internal stress. The internal stress reduction by thermal dissociation ta-C coating film with increasing temperature is confirmed through the curvature radius of the ta-C coating according to the temperature of the SUS plate. As the coating temperature increased, the mechanical properties (hardness, modulus, toughness) deteriorated, which is in agreement with the Raman analysis results. As the temperature increased, the sp² phase ratio increased owing to the dissociation of the sp³ phase. The friction and wear properties are related to the process temperature during ta-C coating. Low friction and wear properties are observed in high hardness samples manufactured at 50℃, and wear resistance properties decreased with increasing temperature. The contact area is expected to increase owing to the decrease of hardness(72 GPa to 39 GPa) and fracture toughness with increasing temperature which accelerated wear because of the debris generated. It was confirmed that at process temperature of over than 100℃, the bond structure of the carbon film changed, and the effect of excellent internal stress was reduced. However, the wear resistance simultaneously decreased owing to the reduction in fracture toughness. Therefore, in order to increase industrial utilization, optimum temperature conditions that reduce internal stress and retain mechanical properties.

• Tribology and Lubricants
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• v.32 no.4
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• pp.125-131
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• 2016

In recent years, thick ta-C coating has attracted considerable interest owing to its existing and potential commercial importance in applications such as automobile accessories, drills, and gears. The thickness of the ta-C coating is an important parameter in these applications. However, the biggest problems are achieving efficient coating and uniformity over a large area with high-speed deposition. Feasibility is confirmed for the ta-C coating thickness of up to 9.0 µm (coating speed: 3.0 µm/h, fixed substrate) using a single FCVA cathode. The thickness was determined using multiple coating cycles that were controlled using substrate temperature and residual stresses. In the present research, we have designed a coating system using FCVA plasma and produced enhanced thick ta-C coating. The system uses a specialized magnetic field configuration with stabilized DC arc plasma discharge during deposition. To achieve quality that is acceptable for use in automobile accessories, the magnetic field, T-type filters, and 10 pieces of a multi-cathode are used to demonstrate the deposition of the thick ta-C coating. The results of coating performance indicate that uniformity is ±7.6 , deposited area is 400 mm, and the thickness of the ta-C coating is up to 5.0 µm (coating speed: 0.3 µm/h, revolution and rotation). The hardness of the coating ranges from 30 to 59 GPa, and the adhesion strength level (HF1) ranges from 20 to 60 N, depending on the ta-C coating.