• 대한기계학회논문집A
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• 제37권4호
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• pp.467-473
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• 2013

본 연구에서는 SU-8 박막의 마이크로시스템으로의 트라이볼로지적 응용을 목적으로 하여, 원자간 힘 현미경(AFM) 과 콜로이드 프로브를 이용한 실험 및 유한요소해석 기법을 이용하여 SU-8 코팅층의 두께에 따른 트라이볼로지적 특성을 고찰하였다. SU-8 시편은 스핀 코팅기법을 이용하여 두께를 다르게하여 제작하였다. 실험결과 코팅두께가 증가함에 따라 마찰력과 점착력이 감소하여 박막두께에 따른 차이가 존재함을 알 수 있었고, SU-8 표면이 Si 표면에서보다 더 낮은 점착력과 마찰력을 보여주었다. 또한, 시뮬레이션을 통해 두께별로 박막 파손을 유발시키는 임계하중(압력)이 존재하며, 본 연구에서의 200~800 nm 두께범위에서는 1.2~1.8 GPa 로 측정되었다.

• 한국재료학회지
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• 제15권3호
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• pp.149-154
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• 2005

Teflon like fluorocarbon thin films have been deposited on silicon and oxide molds as an antistiction layer for the hot embossing process by an inductively coupled plasma (ICP) chemical vapor deposition (CVD) method. The process was performed at $C_4F_8$ gas flow rate of 2 sccm and 30 W of plasma power as a function of substrate temperature. The thickness of film was measured by a spectroscopic ellipsometry. These films were left in a vacuum oven of 100, 200 and $300^{\circ}C$ for a week. The change of film thickness, contact angle and adhesion and friction force was measured before and after the thermal test. No degradation of film was observed when films were treated at $100^{\circ}C$. The heat treatment of films at 200 and $300^{\circ}C$ caused the reduction of contact angles and film thickness in both silicon and oxide samples. Higher adhesion and friction forces of films were also measured on films treated at higher temperatures than $100^{\circ}C$. No differences on film properties were found when films were deposited on either silicon or oxide. A 100 nm silicon template with 1 to $500\;{\mu}m$ patterns was used for the hot embossing process on $4.5\;{\mu}m$ thick PMMA spun coated silicon wafers. The antistiction layer of 10 nm was deposited on the silicon mold. No stiction or damages were found on PMMA surfaces even after 30 times of hot embossing at $200^{\circ}C$ and 10 kN.

• 한국강구조학회 논문집
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• 제20권1호
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• pp.67-79
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• 2008

본 연구에서는 매입형 합성보에서 전체 보의 휨거동 및 합성면에서의 상대변위(Slip) 등을 분석함으로써 화학적 부착, 부착파괴 후 기계적 맞물림 및 마찰작용, 전단 스터드가 합성보 전체의 강도 및 강성과 합성단면에서의 전단합성거동에 기여하는 정도를 해석해 보고자 한다. 이를 위해 U자형 성형강판을 이용한 합성보 및 CT형강 용접방식 강판성형 합성보에 대해 구조성능 실험과 유한요소해석을 수행하였다. 실험 및 해석결과에 의하면, 전단 스터드의 설치 유무에 따라 매입형 합성보의 극한 모멘트성능 차이는 약 10% 미만을 나타내었다. 이것은 강재 보의 단면형상으로 인한 화학적 및 기계적 부착력이 크기 때문에 이에 의한 합성작용으로도 일정 이상의 모멘트성능 발휘가 가능하여 완전합성상태에 해당하는 소성 모멘트내력과의 차이가 비교적 크지 않으며, 합성율이 증가하는 것에 비해 휨모멘트 내력은 완만하게 증가하기 때문으로 나타났다.

• Tribology and Lubricants
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• 제38권6호
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• pp.255-260
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• 2022

This research presents tetrahedral amorphous (ta-C) coating on the artificial tooth for improving the durability and functionality (esthtics, foreign body of tooth) by filtered cathodic vacuum arc (FCVA). A differentiated coating method is required for a ta-C coating on polymer owing to the low melting point of the polymer, inter-facial adhesion, low friction, and non-conductivity. Herein, ta-C coating is applied below 50℃, and the potential difference of the carbon plasma drawn to the substrate was controlled by applying a positive duct bias voltage without using a substrate bias voltage. Consequently, the ta-C coating with a thickness of 70nm using the duct bias condition of 20V with the highest plasma intensity satisfies the esthetics of the artificial tooth and had a 5B level of inter-facial adhesion. In addition, the composite hardness of ta-C/polymer is 380 MPa, and correlations with esthetics, sp³ bonding, and mechanical properties. The friction coefficient (CoF) of the ta-C coating in a water-lubricated environment is 0.07, showing a six-fold reduction in CoF compared with that of a polymer.

• Journal of the Korean Wood Science and Technology
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• 제19권1호
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• pp.71-80
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• 1991

This study was carried out to investigate replaceable species with the conventional sounding board sitka spruce. by comparing the dynamic properties such as density, dynamic Young's modulus and internal friction Dynamic Young's modulus. internal friction of longitudinal and radial direction measured in free mass-free boundary condition for facile vibration analysis and measured by forced vibration method. Dynamical properties of four species were measured on squared plate specimen that the four edges were hung vertically by threads and driven magnetically through an iron piece glued on the specimen, by the use of condenser microphone as vibration transducer, and analyzed by FFT analyzer. The results obtained were as follows: 1. Chaldni method using aluminum powder was proper to identify the vibration mode in the plate vibration and it was possible to verify the resornance mode. 2. It was considered that it was necessary to investigate the influence of adhesive part on the plate vibration when the sounding board was made by two or three small board adhesion. 3. It was considered that plate vibration method, which was a superior to the vibration test of beam, was suitable for selecting suounding board because dynamic Young's modulus and internal friction show different order according to longitudinal and radial direction. 4. Paulownia tomentosa Thunb.) Steudel has been considered to be replaceable species with sitka spruce because it has high dynamic Young's modulus compared with low density, low internal friction, and K value of Paulownia tomentosa (Thunb.) Steudel is greater than that of sitka spruce.

• 마이크로전자및패키징학회지
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• 제12권3호
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• pp.213-217
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• 2005

ITO(indium tin oxide)/Glass 기판위에 정공 수송층으로 PEDOT:PSS[poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)]과 발광층으로 MEH-PPV[poly(2-methoxy-5-(2-ethyhexoxy)-1,4phenylenvinylene)]의 고분자를 사용하여 ITO/PEDOT:PSS/MEH-PPV/Al 구조를 갖는 고분자 유기 발광다이오드 (polymer light emitting diode: PLED)를 제작하였다. 고분자 유기 발광다이오드 제작시 MEH-PPV의 농도$(0.1\;wt\%\~0.9\;wt\%)$가 발광층 표면 거칠기와 박막층판의 마찰계수(friction coefficient)에 미치는 영향을 조사하였다. MEH-PPV의 농도를 $0.1\;wt\%$에서 $0.9\;wt\%$로 증가함에 따라 발광층의 RMS 값은 1.72 nm 에서 1.00 nm로 감소하여 거칠기가 개선되는 경향을 보여 주었다. 또한 발광층 박막의 마찰계수는 0.048에서 0.035로 감소하여 박막의 접합상태가 나빠지는 현상을 나타내었다. $0.5\;wt\%$의 농도를 갖는 PLED 다이오드에서 최대 휘도인 $409\;cd/m^2$ 값을 얻었다.

• Tribology and Lubricants
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• 제29권5호
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• pp.298-303
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• 2013

In this work, the effect of applied load on the wear behavior of Al/SiC composites was studied. Al/SiC composites were fabricated following the thermal spray process. Dry sliding wear tests were performed on these composites under four different applied loads, i.e., 5, 10, 15, and 20 N. The wear behaviors of the composites under these applied loads were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Under applied loads of up to 15 N, the wear rates of Al/SiC composites decreased with an increase in the applied load because of the formation of an adhesion layer on the worn surface. However in the case of an applied load of 20 N, the wear rate was significantly high because the formation and fracture of the adhesion layer were repeated continuously. These results show that the wear behaviors of the tested composites are significantly influenced owing to the applied loads.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.660-664
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• 2008

Titanium nitride (TiN) thin films are widely used for hard coatings due to their superior hardness, chemical stability, low friction and good adhesion properties. In this study, we investigated the effect of DC power on the characteristics of TiN thin films deposited on Si and glass substrates by DC magnetron sputtering using TiN target. We made TiN films of 300 nm thickness with various DC powers. The structural properties of films are investigated by x-ray diffractions (XRD) and tribological properties are measured by nano-indentation, nano-scratch tester. The rms roughness was measured by atomic forced microscopy (AFM). In the result, TiN films had the smooth surface and exhibited (111) directions with the increase of DC Power. Also, especially in case of 175 W DC power, TiN film exhibited the maximum hardness about 8 GPa, and the critical load near 25.

• 대한기계학회논문집
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• 제12권3호
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• pp.489-496
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• 1988

본 연구에서는 오스템퍼링 처리된 구상흑연주철의 오스템퍼링 처리온도와 유 지시간을 변화시킨 후 대기중의 건조미끄름마찰실험을 하여 내마멸특성을 검토하는 것 을 목적으로 하였다.

• 열처리공학회지
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• 제13권2호
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• pp.91-97
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• 2000

The structure and mechanical properties of TiN and TiCN thin films deposited on STD61 steel substrates by the RF-sputtering methods has been studied by using XPS, XRD, micro-hardness tester, scratch tester, and wear-resistance tester. XPS results showed that the TiCN thin film formed with chemical bonding state. The TiN thin films grew with (111) orientation having the lowest strain energy by compressive stress, whereas the TiCN thin films grew with both (111) and (200) orientation, but (200) orientation having the lowest surface energy becomes dominant as carbon contents increase. The pre-etching treatment of substrate did not affect on the preferred orientation of thin films, but it played an important role in improving mechanical properties of thin films such as the hardness, adhesion and wear- resistance. Especially, the TiCN thin films showed the superior wear resistances due to high hardness and low friction coefficient compared with TiN thin films.