• 한국진공학회지
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• 제4권S2호
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• pp.163-169
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• 1995

Ion beam assisted deposition(IBAD) technique was used to synthesize hard coatings including diamond-like carbon(DLC), carbon nitride(CN) and metal-ceramic multilayered films. It was found that DLC films formed at low energy ion bombardment possess more $Sp^3$ bonds and much higher hardness. The films exhibited an excellent wear resistance. Nanometer multialyered Fe/TiC films was deposited by ion beam sputtering. The structure and properties were strongly dependent on the thickness of the individual layers and modulation wave length. It was disclosed that both hardness and toughness of the films could be enhanced by adjusting the deposition parameters. The CN films synthesized by IBAD method consisted of tiny crystallites dispersed in amorphous matrix, which were identified by electron diffraction pattern to be $\beta -C_3N_4$.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.54-58
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• 1999

We deposited diamond-like carbon (DLC) films using ion beam sputtering of a graphite target on flat substrates for use as a thin film field emitter. An n-type silicon wafer, titanium-coated silicon, and indium tin oxide (ITO) coated glass were used as a substrate. All films exhibited a sudden increase in the emission after a breakdown occurred at high voltage. The morphology of the films after the breakdown depended on the substrate. On ITO and Ti substrates, the DLC film peeled off upon breakdown, but on the Si substrate the surface melting due to breakdown resulted in the formation of various structures such as a sharp point, mound, and crater. By scanning the deformed surface with a tip anode, we found that the emission was concentrated at the deformed sites, indicating that the field enhancement due to the morphology change was responsible for the increased emission.

• Tribology and Lubricants
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• 제18권4호
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• pp.267-272
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• 2002

Nano adhesion between SPM(scanning probe microscope) tips and DDPO$_4$(octadecylphosphoric acid ester.) and ODPO$_4$(octadecylphosphoric acid ester) SAM(self-assembled monolayer.) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes with the applied normal load. DDPO$_4$ and ODPO$_4$ SAM were formed on Ti and TiOx surfaces. Ti and TiOx were coated on the Si wafer by ion sputtering. Adhesion and friction of DDPO$_4$ and ODPO$_4$ SAM surfaces were compared with those of OTS(octadecyltrichlorosilane) SAM and DLC surfaces. DDPO$_4$ and ODPO$_4$ SAM converted the Ti and TiOx surfaces to be hydrophobic. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare surfaces. Work of adhesion was also discussed to explain how the surface was converted into hydrophobic Results also showed that tribological characteristics of DDPO$_4$ and ODPO$_4$ SAM had good properties in the adhesion, friction, wetting angle and work of adhesion. DDPO$_4$ and ODPO$_4$ SAM could be one of the candidates for the bio-MEMS elements.

• Tribology and Lubricants
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• 제25권1호
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• pp.20-24
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• 2009

TiC-derived carbon coatings have been synthesized at $600^{\circ}C$ temperature treatment with $H_2/Cl_2$ mixture gases. From Raman spectroscopy measurements, the modified layer was covered with carbon and the thick-ness of the layer was increased with increasing reaction time. And $I_D/I_G$ ratio was decreased with increasing reaction time. The superior tribological property was obtained from TiC reacted with $Cl_2$ gas for 2 hrs. And the tribological property measurements indicate that TiC-derived carbon layer has $0.9{\times}10_{-6}mm^3/Nm$ in wear coefficient and 0.13 in friction coefficient.

• Tribology and Lubricants
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• 제23권6호
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• pp.261-265
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• 2007

Carbide-derived carbon coating has been synthesized by low temperature treatment of TiC disk with $H_2/Cl_2$ mixture gases. A variety of physical measurements indicated that Ti was extracted and carbon layer was formed by exposure of $Cl_2$ gas. The $I_D/I_G$ ratio increased with increasing $Cl_2$ gas concentration. Wear coefficient and frictional coefficient varied with $Cl_2$ gas concentration. When the $Cl_2$ gas concentration decreased to 3.3 vol%, the friction coefficient approach a minimum. The results showed that degree of graphite crystallinity and variation of porosity due to the $Cl_2$ gas content were responsible for different tribology performance.

• 한국정밀공학회지
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• 제22권6호
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• pp.159-167
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• 2005

This work focuses on the effects of crack free friction on Mode II stress intensity factors, $K_{II}$, for a vertical surface crack in a two-dimensional finite element model of TiN/steel subject to rolling contact. Results indicate that maximum $K_{II}$ values, which occur when the load is adjacent to the crack, may be significantly reduced in the presence of crack face friction. The reduction is more significant for thick coatings than for thin. Crack extension and increased layer thickness result in increased $K_{II}$ values. The effect of crack face friction on compressive $K_I$ values appears negligible. Comparative results are presented for $MoS_2/steel$ and diamond-like carbon(DLC)/Ti systems.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.254-254
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• 2013

마그네트론 스퍼터링은 그 단순한 구조로 인하여 신뢰성과 확장성이 높은 기술이다, 이로 인해 DLC, ITO 등의 산업 분야에서 많이 사용하는 박막 공정 기술이다. 하지만 인듐과 같은 희토류 금속의 가격이 최근 상승함에 따라 나타난 낮은 타겟 효율성의 문제와 낮은 파워 밀도로 인한 기판의 추가적인 bias 추가에 따른 비용상승, 그리고 reactive 스퍼터링 시 낮은 증착률 등의 문제점들 또한 존재한다. 이러한 단점들을 해결하기 위해 많은 연구들이 이루어 졌으며, 높은 파워 밀도를 위해 High power Impulse Plasma Magnetron Sputtering (HIPIMS) 기술과 타겟 사용률을 높이기 위한 High Target Utilization Sputtering (HITUS) 등의 기술 등이 개발되었다. 본 연구에서는 직류 전원을 사용한 High density Plasma Sputtering System (HIPASS)이라 명하는 고밀도 원거리 플라즈마 소스를 이용한 스퍼터링 이용해 증착한 박막의 특성을 연구 하였다. Hollow cathode discharge에서 발생한 고밀도 플라즈마가 외부 유도 자장 코일에 의하여 타겟 표면까지 도달하게 되며, 스퍼터링 타겟의 고전압 bias에 의해 플라즈마 이온들이 가속이 이루어져 스퍼터링 공정이 이루어 지게 된다. 본 연구의 공정에서 타겟 사용 효율은 최대 90%까지 이며, 원거리 플라즈마 소스에서의 이온으로 스퍼터링을 실시함으로 인해 스퍼터링 전압과 전류의 독립적인 조절이 가능 하다. 본 연구에서 HIPASS을 이용하여 기판에 추가적인 전압 인가 없이 Ti 타겟과 아르곤/질소 혼합가스를 사용하여 TiN 박막을 증착 하였다. TiN의 증착률은 약 44 nm/min였으며, 이 박막의 XRD 분석 결과 TiN (111), (200), (220) 면들이 관찰이 되었다. 높은 스퍼터링 입자 에너지에서 증착 된 TiN 박막에서 우선적으로 나타나는(200)과 (220) 면들이, 본 실험에서는 기판에 추가적인 전압인가 없이도 우선방위 성장을 보였다. 이 박막의 micro-hardness 측정 결과 약 34.7 GPa이며, 이는 UBM 이나 HIPIMS에서 보여주는 결과에 준하거나 그 이상의 수치이다. 이와 같은 결과는 본 연구에서 사용한 HIPASS 증착 공정이 높은 스퍼터링 입자 에너지를 가지기에 고밀도의 TiN 박막이 증착 된 결과로 볼 수 있다.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.461-467
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• 2021

열경화성 소재를 이용하여 열경화방식의 웨이퍼 레벨 렌즈를 성형할 때 발생될 수 있는 불량요인 중 이형과정에서 성형 렌즈의 금형 고착문제는 웨이퍼 레벨에서 성형된 기판의 파손 및 기판의 변형으로 성형된 웨이퍼 기판의 적층시 웨이퍼 양면의 렌즈 형상 및 센터 정렬 오차에 영향을 미친다. 본 연구에서는 웨이퍼 레벨 렌즈 성형 공정에서 이형력에 영향을 미치는 인자를 검토하기 위한 실험을 수행하였다. 먼저 상·하 금형의 코팅 재질에 따른 이형력을 검토하기 위하여 금형 표면을 ITO 및 Ti로 표면처리 후 O2분위기에서 플라즈마 처리하였고, 또한 DLC 코팅도 진행하였으며 경화 및 이형성을 검토하였다. 그 결과를 바탕으로 pull-off 실험을 위한 코팅방법을 선정하였다. 또한 경화공정조건에 따른 이형력을 측정하기 위하여 압력을 유지하면서 경화시키는 방법과 일정한 간격을 유지하면서 경화시키는 방법을 실험적으로 적용하였다. 그 결과 Ti 코팅 후 O2 플라즈마 표면처리 방법이 이형력을 감소시키고 위치를 제어하면서 경화시킬 경우 경화수축에 의해 경화 중 계면의 접착에너지를 감소시켜 보다 나은 이형이 될 수 있음을 확인하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.207-214
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• 2002

Nano adhesion between SPM (scanning probe microscope) tips and $DDPO_{4}$ (dodecylphosphoric acid ester) and $ODPO_{4}$ (octadecylphosphoric acid ester) SAM (self-assembled monolayer) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes with the applied normal load. $DDPO_{4}$ and $ODPO_{4}$ SAM were formed on TiMe and TiOx surfaces. TiMe and TiOx were coated on the Si wafer by ion sputtering. Adhesion and friction of $DDPO_{4}$ and $ODPO_{4}$ SAM surfaces were compared with those of OTS (octadecyltrichlorosilane) SAM and DLC surfaces. $DDPO_{4}$ and $ODPO_{4}$ SAM converted the TiMe and TiOx surfaces to be hydrophobic. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare surfaces. Work of adhesion was also discussed to explain how the surface was converted into hydrophobic. Results also showed that tribological characteristics of $DDPO_{4}$ and $ODPO_{4}$ had good properties in the adhesion, friction, wetting angle and work of adhesion. $DDPO_{4}$ and $ODPO_{4}$ SAM could be one of the candidates for the bio-MEMS elements.

• 드라이브 ㆍ 컨트롤
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• 제15권1호
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• pp.10-15
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• 2018

The hydraulic cylinder seals are used not only to protect leakage of the working fluids but also to prevent incoming of foreign particles into the system. Chromium plating is generally applied to improve corrosion and wear resistance. It has been noticed that sealing surface damage occurs due to the hard foreign/wear particles contained in the hydraulic oil. In this study, a three-bodied sliding contact problem related with a PTFE seal, a spherical particle and chrome-plated steel substrate is modeled to investigate the relations to wear mechanism. Using the nonlinear finite element software, MARC/MENTAT, the deformed shapes, the von Mises and first principal stress distributions with plating thickness were compared. The sealing surface was mainly abraded by hard particles embedded in the seal. The plastic deformation of the steel substrate decreased with thicker plating. Hence it could be more effective to coat the sealing surface of a hydraulic cylinder with a hard material such as TiN, TiC and DLC.