• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 동계연구발표회 논문개요집
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• pp.124-125
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• 2002

최근 자성막의 놀은 자기기록 밀도증가에 따른 고밀도 자성기록매체인 하드디스크(HDD)는 현재 80GByte까지의 저장용량을 가진 하드디스크의 자성합금층 보호막으로 DLC(Diamond-Like Carbon)가 이용되고 있다. 고저장용량을 가지는 하드디스크의 보호막 두께가 점차 얇아짐에 따라 보호막 재료의 경도 및 윤활성은 더욱 중요시되고 있다. 그러나, 보호막의 두께가 감소하면서 현재 적용되고 있는 DLC막으로는 조만간 물리적 한계에 도달할 것으로 예상된다. (중략)

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.164-165
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• 2007

Si(중간층)/DLC(diamond-like carbon)막은 스퍼터와 이온소스(ion source)법에 의한 복합방식(hybrid method)을 이용하여 3mTorr의 반응가스 벤젠($C_6H_6$)분위기에서 Si wafer에 기판온도 $130^{\circ}C$로 180분간 증착하였다. 평가는 표면과 단면에 대해 주사전자현미경(scanning electron microscopy, SEM)과 투자전자현미경(trasmission electron microsope, TEM)으로 관찰하였다. 경도와 마찰계수는 나노인텐터(nanoindetor)와 마모시험기를 이용하였으며, 박막의 구조는 라만스펙트럼으로 분석하였다. 그 결과 박막의 두께는 약 $0.9{\mu}m$, 표면조도는 약 $0.34{\sim}1.64nm$로 평탄한 표면을 가지며 경도는 약 $35{\sim}37GPa$, 마찰계수는 약 $0.02{\sim}0.07$로 관찰되었다. 라만분광법과 전자회절패턴에 의해 IG/ID의 함량비는 $0.54{\sim}0.59$로 $sp^2$와 $sp^3$가 혼재된 전형적인 비정질 구조임을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.135-135
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• 1999

It is well known that Raman spectroscopy is powerful tool in analysis of sp3/sp3 bonding fraction in diamond-like carbon(DLC) films. Raman spectra of DLC film is composed of D-peak centered at 1350cm-1 and G-peak centered at 1530cm-1. The sp3/sp3 fraction is qualitatively acquired by deconvolution method. However, in case of DLC film, it is generally observed that G-peak position shifts toward low wavenumber as th sp3 fraction increases. However, opposite results were frequently observed in ta-C films. ta-C film has much higher residual compressive stress due to its high sp3 fraction compared to the DLC films deposited by CVD method. Effect of residual stress on G-peak position is most recommendable parameter in Raman analysis of ta-C, due to its smallest fitting error among many parameters acquired by peak deconvolution of symmetric spectra. In current study, the effect of residual stress on Raman spectra was quantitatively evaluated by free-hang method. ta-C films of different residual stress were deposited on Si-wafer by modifying DC-bias voltage during deposition. The variation of the G-peak position along the etching depth were observed in the free-hangs of 20~30${\mu}{\textrm}{m}$ etching depth. Mathematical result based on Airy stress function, was compared with experimental results. The more reliable analysis excluding stress-induced shift was possible by elimination of the Raman shift due to residual compressiove stress.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.93-93
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• 2000

수소화된 비정질 탄소(a-C:H)는 그 증착 조건에 따라서 여러 가지 다른 구조와 특성을 갖게 되며, 특히 DLC(diamond-like carbon) 및 CNT(Carbon nanotube)는 FED (field emission display) 개발 면에서 중요하게 연구되고 있다. 우리는 a-C:H 박막을 PECVD (plasma-enhanced chemical vapor deposition) 방법으로 증착하고 CH4 가스를 사용하였고 기판 온도는 상온-32$0^{\circ}C$ 사이에서 변화되었다. 기판은 Corning 1737 glass, quartz, Si, Ni 등을 사용하였다. 증착 압력과 R.F. power는 각각 0.1-1 Torr 와 12-60w 사이에서 변화되었다. ESR 측정은 X-band(주파수 약 9 GHz)에서 그리고 상온에서 행해졌다. 상온에서의 스핀밀도는 약한-표준피치(weak-pitch standard) 스펙트럼과 비교하여 얻을 수 있었다. 그리고 a-C:H 박막의 구조는 He-Ne laser(파장 632.8 nm)를 이용하는 micro-Raman spectroscopy로 분석하였다. 증착조건에 따른 스핀밀도의 변화 및 Raman 스펙트럼에서의 D-peak, G-peak의 위치 및 반치록, I(D)/I(G) 등을 조사하였다. 증착된 a-C:H 박막은 R.F.power가 증가할수록 대체로 스핀밀도가 증가하였으며, Raman 스펙트럼에서의 I(D)/I(G) 비율은 대체로 감소하였다. 증착된 박막들은 polymer-like Carbon으로 추정되었으며, 스핀밀도가 증가할수록 대체적으로 흑연 구조 영역이 증가됨을 알 수 있었다. 또한 glass나 Si 기판에 비해 Ni 기판위에서 polymer-like Carbon 구조는 향상되는 경향을 보였다.

• 한국결정성장학회지
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• 제24권1호
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• pp.33-40
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• 2014

전기방사법(Electrospinning technique)을 이용하여 PVdF-HFP(Poly vinylidene fluoride-co-hexafluoropropylene) 멤브레인을 제조하고, 그 멤브레인 표면위에 DLC(Diamond-like carbon) 코팅공정을 적용하여 멤브레인의 표면변화 및 접촉각 변화를 조사하였다. Ar 플라즈마 처리시간 및 처리조건에 따라 PVdF-HFP 멤브레인 파이버 표면이 주름(wrinkles)형태로 변화 하였다. 이러한 Ar 플라즈마 처리가 된 PVdF-HFP 멤브레인은 초친수성(super-hydrophilic) 특성으로 변했지만, 초친수성 PVdF-HFP 멤브레인에 DLC 코팅공정을 적용하면 반대로 초소수성(super-hydrophobic) 특성으로 변화되었다. 이러한 특성을 가진 표면을 접촉각 측정과 XPS, FE-SEM 측정으로 분석하였다. 따라서 화학적 조성과 표면 형상에 의해 접촉각 특성을 가지는 것으로 확인하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.71-72
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• 2007

In this study, we investigated the fabrication of MLR (multi-layer resist) with a very thin diamond-like carbon (DLC) layer. ArF PR/$SiO_2$/DLC MLR structure was investigated and etching characteristics of the DLC layer was patterned using $SiO_2$ hard-mask by varying the process parameters such as different high-frequency/low-frequency combination ($f_{LF}/f_{HF}$), HF/LF power ratio ($P_{HF}/P_{LF}$), $O_2$ flow and $N_2$ flow rate in $O_2/N_2$/Ar plasmas. The results indicated an increased etch rate of DLC for the higher $f_{LF}/f_{HF}$ combination and for the increased low-frequency power ($P_{LF}$). And the etch rate of DLC was decreased with increasing the $N_2$ flow rate in $O_2/N_2$/Ar plasmas. In order to confirm the application of DLC MLR for the etching process of silicon oxide, the stack of ArF PR/BARC/$SiO_2$/DLC/TEOS/Si was investigated.

• Tribology and Lubricants
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• 제37권3호
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• pp.106-111
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• 2021

There are several studies on reducing the friction that occurs on the relative sliding contact surface of moving parts under extreme environments. In particular, a solid lubricated bearing is studied to solve the tribological problem with friction reduction and durability parts using solid lubricants (lead or silver) in a vacuum atmosphere. Galinstan is mainly used as a liquid metal lubricant, but it is inevitable to have limited tribological applications owing to its high coefficient of friction. Many researchers work on surface texturing for surface modification and precision processing methods. To increase durability and low friction, DLC coating with hydrophobicity is applied on the contact surface texture. Therefore, using an untextured specimen, a dimple specimen, and a DLC-coated dimple specimen under liquid metal lubrication, this paper presents the following experimental sliding friction characteristics in the sliding friction test. 1) The average coefficient of friction of the DLC-coated dimple specimen and dimple specimen are lower compared to that of a non-patterned specimen. 2) In the DLC-coated dimple specimens, the average coefficient of friction changes according to the change in the dimple density. 3) DLC-coated dimple specimens with a density of 12.5 have the lowest average coefficient of friction under 41.6 N of normal load and 143.3 RPM.

• Tribology and Lubricants
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• 제33권4호
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• pp.127-133
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• 2017

In order to characterize the adhesive properties and failure mechanisms of diamond-like carbon (DLC) films of two different thicknesses (130 nm and $1.2{\mu}m$), deposited by plasma-enhanced chemical vapor deposition on a Si substrate, scratch testing with a micro-indenter ($12.5{\mu}m$ tip radius) was performed under a linearly increasing load. These scratch tests were conducted under the same test conditions for both films. The critical load of each film was estimated from the scratch test results, based on a sharp increase in the coefficient of friction and a clear distinction of failure modes. The critical load was the basis for evaluating the adhesion strength of the films, and the $1.2{\mu}m-thick$ DLC film had superior adhesion strength. For better understanding of the failure modes, the following analyses were conducted: friction behavior and scratch tracks analysis using scanning electron microscopy, energy-dispersive spectroscopy, and 3-D profilometry. The scratch test results showed that failure modes were related to the thickness of the films. The 130 nm-thick DLC film underwent cohesive failure modes (cracks and chipping) before reaching to a gross failure stage. On the other hand, the thicker DLC film ($1.2{\mu}m-thick$) did not exhibit micro cracks before a sudden gross failure of the film together with the evidence of cracking and chipping of the Si substrate.

• 한국해양공학회지
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• 제24권6호
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• pp.76-80
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• 2010

Oil hydraulic piston pumps are being extensively used around the world, because of their simple design, light weight, effective cost, etc. An oil hydraulic pump is likely to have the serious problems of high leakage, friction, and low energy efficiency after a long period of use. In an oil hydraulic piston pump, the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this study, the wear property of the SACM645 material with DLC coating used for a hydraulic piston pump was determined by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, five different types of specimens were prepared. The maximum tensile strengths of the QT and QT Nitration specimens had similar values of about 800 MPa, but the strains indicated a big difference. In a wear test, the wear characteristic of the DLC coating specimen was shown to be excellent. The QT, QT + IH, QT + Nitration, and matirx specimen showed similar wear characteristics. In the case of a dry condition without oil, the DLC coating specimen had good wear resistance, with no wear shown.

• 한국표면공학회지
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• 제52권3호
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• pp.163-170
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• 2019

Durability of instrument is one of the most important factor to ensure accurate treatment and decrease failure for the orthopedic surgical operation. Normally, a set-screw driver tip has been processed with hard coating for their higher durability and wear resistance. And several surface modification methods were obtained such as titanium nitride (TiN) coating, diamond like carbon coating, other nitriding, and etc. In this study, we have surface modified on set-screw driver tip with TiN and DLC, investigated whether the TiN and DLC coatings affect the mechanical properties and durability of the set-screw driver tip in the pedicle screw system. The surface morphologies were observed with scanning-electron microscopy (SEM), and the static/dynamic torsional properties were investigated with universal testing machine based on ASTM F543. Coating thickness of each coatings were commonly around $1^{\circ}C$. Static torsional stiffness, and ultimate torque values for DLC and TiN coated samples were significantly higher than those of non-coated sample by the pared T-test. Surface morphology of after the dynamic torsional test was more clean with less scratch or friction traces from DLC coating than that of TiN coating and non-coated sample.