• 한국표면공학회지
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• 제47권2호
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• pp.75-80
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• 2014

Nanocrystalline diamond(NCD) films on steel(SKH51) has been investigated using SiC interlayer film. SiC was deposited on SKH51 or Si wafer by RF magnetron sputter. NCD was deposited on SiC at $600^{\circ}C$ for 0.5~4 h employing microwave plasma CVD. Film morphology was observed by FESEM and FIB. Film adherence was examined by Rockwell C adhesion test. The growth rate of NCD on SiC/Si substrate was much higher than that on SiC/SKH51. During particle coalescence, NCD growth rate was slow since overall rate was determined by the diffusion of carbon on SiC surface. After completion of particle coalescence, NCD growth became faster with the reaction of carbon on NCD film controlling the whole process. In the case of SiC/SKH51 substrate, a complete NCD film was not formed even after 4 h of deposition. The adhesion test of NCD/SiC/SKH51 samples revealed a delamination of film whereas that of SiC/SKH51 showed a good adhesion. Many voids of less than 0.1 ${\mu}m$ were detected on NCD/SiC interface. These voids were believed as the reason for the poor adhesion between NCD and SiC films. The origin of voids was due to the insufficient coalescence of diamond particles on SiC surface in the early stage of deposition.

• 열처리공학회지
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• 제31권4호
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• pp.187-193
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• 2018

In this study, the electrical conductivity, transmittance and gas barrier properties of diamond-like carbon (DLC) thin films were studied. DLC is an insulator, and has transmittance and oxygen gas barrier properties varying depending on the thickness of the thin film. Recently, many researchers have been trying to apply DLC properties to specific industrial conditions. The DLC thin films were deposited by PECVD (Plasma Enhanced Chemical Vapor Deposition) process. The doping gas was used for the DLC film to have electrical conductivity, and the optimum conditions of transmittance and gas barrier properties were established by adjusting the gas ratio and DLC thickness. In order to improve the electrical conductivity of the DLC thin film, $N_2$ doping gas was used for $CH_4$ or $C_2H_2$ gas. Then, a heat treatment process was performed for 30 minutes in a box furnace set at $200^{\circ}C$. The lowest sheet resistance value of the DLC film was found to be $18.11k{\Omega}/cm^2$. On the other hand, the maximum transmittance of the DLC film deposited on the PET substrate was 98.8%, and the minimum oxygen transmission rate (OTR) of the DLC film of $C_2H_2$ gas was 0.83.

• Tribology and Lubricants
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• 제39권1호
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• pp.8-12
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• 2023

This study presents a molecular simulation of adhesion control between carbon nanotube (CNT) and Ag thin film deposited on silicon substrate. Rough and flat Ag thin film models were prepared to investigate the effect of surface roughness on adhesion force. Heat treatment was applied to the models to modify the adhesion characteristics of the Ag/CNT interface based on thermal wetting. Simulation results showed that the heat treatment altered the Ag thin film morphology by thermal wetting, causing an increase in contact area of Ag/CNT interface and the adhesion force for both the flat and rough models changed. Despite the increase in contact area, the adhesion force of flat Ag/CNT interface decreased after the heat treatment because of plastic deformation of the Ag thin film. The result suggests that internal stress of the CNT induced by the substrate deformation contributes in reduction of adhesion. Contrarily, heat treatment to the rough model increases adhesion force because of the expanded contact area. The contact area is speculated to be more influential to the adhesion force rather than the internal stress of the CNT on the rough Ag thin film, because the CNT on the rough model contains internal stress regardless of the heat treatment. Therefore, as demonstrated by simulation results, the heat treatment can prevent delamination or wear of CNT coating on a rough metallic substrate by thermal wetting phenomena.

• 폴리머
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• 제25권1호
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• pp.133-141
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• 2001

산화억제제로 사용한 이규화 몰리브덴($MoSi_2$)의 함량에 따른 일방향 탄소/탄소 복합재료의 마찰 및 마모 특성에 관하여 대기상태 하에서 정속마찰시험기를 이용하여 측정하였다. 그 결과, 탄소/탄소 복합재료는 마찰온도 150~180${\circ}C$에서 급격한 마찰계수의 전이, 즉 normal wear 영역에서의 낮은 마찰계수(${\mu}$=0.15~0.2)에서 dusting wear 영역에서의 높은 마찰계수(${\mu}$=0.5~0.6)로의 전이를 나타내었다. 이렇게 마찰계수가 전이하는 온도범위의 존재는 탄소/탄소 복합재료로 만든 브레이크가 복합재료의 열적 특성에 큰 영향을 받는다는 것을 의미한다. 그리고 산화억제제인 $MoSi_2$를 가지는 탄소/탄소 복합재료는 이를 함유하지 않은 복합재료에 비해 약 1.5배 정도의 낮은 평균마찰계수 및 마모율을 나타내었으며, 특히 4 wt% $MoSi_2$ 함량을 가진 복합재료가 가장 큰 마모활성화 에너지 값을 나타내었다.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.2007-2013
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• 2017

In order to give hydrophobic surface properties on carbon steel, the fluorinated amorphous carbon films were prepared by using linear 2.45GHz microwave PECVD device. Two different process approaches have been tested. One is direct deposition of a-C:H:F films using admixture of $Ar/CH_4/CF_4$ working gases and the other is surface treatment using $CF_4$ plasma after deposition of a-C:H film with $Ar/CH_4$ binary gas system. $Ar/CF_4$ plasma treated surface with high $CF_4$ gas ratio shows best hydrophobicity and durability of hydrophobicity. Nanometer scale surface roughness seems one of the most important factors for hydrophobicity within our experimental conditions. The properties of a-C:H:F films and $CF_4$ plasma treated a-C:H films were investigated in terms of surface roughness, hardness, microstructure, chemical bonding, atomic bonding structure between carbon and fluorine, adhesion and water contact angle by using atomic force microscopy (AFM), nano-indentation, Raman analysis and X-ray photoelectron spectroscopy (XPS).

• Composites Research
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• 제29권3호
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• pp.104-110
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• 2016

본 논문은 층간 삽입 반응을 이용하여 그래핀을 박리하는 동시에 탄소나노튜브를 개별 분산시키고 이를 복합 필름으로 제조한 결과를 보고한다. 일반적으로 그래핀과 탄소나노튜브의 경우 흑연과 탄소나노튜브 번들로부터의 개별적 박리를 통해 제조될 수 있으나 장시간의 공정 시간을 요구하게 된다. 본 연구에서는 그래핀과 탄소나노튜브의 동시 박리 및 분산을 위해 흑연 및 탄소나노튜브 번들 내로 포타슘 소듐 타르트레이트를 삽입했으며 XRD 분석을 통해 흑연 층간 거리 및 탄소나노노튜브 번들 내 거리의 증가를 확인했다. 제조된 층간삽입화합물로부터 박리된 그래핀 및 탄소나노튜브의 경우 매우 낮은 산화도(< 8.3 at%)를 나타냈으며 제조된 물질을 여과 장치 및 스프레이 전사를 통해 복합 필름으로 제조한 결과 그래핀 및 탄소나노튜브의 단일 필름에 대비하여 복합 필름의 경우 전도성의 향상을 보였다.

• 한국방사선학회논문지
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• 제9권3호
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• pp.131-137
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• 2015

본 연구의 목적은 기존에 사용 중인 X선 발생장치의 촬영대를 따뜻하게 가열하면서도 X선 감약이 적은 탄소나노튜브(carbon nano tube, CNT) 발열체를 사용하여 가열장치를 구비한 X선 발생장치용 부착형 촬영대의 고안 및 설계를 하고자 한다. 고안된 제품의 구성은 부착형 탄소발열체 촬영대로서 기존 X선 촬영대, 탄소나노튜브 면상발열체, 전극선, 난연 처방된 보호필름과 바닥필름으로 구성되어 있다. 본 고안 제품의 특징과 장점은 냉기(冷氣)를 느끼는 촬영대에서 환의를 착용하고 검사를 받는 환자에게 온화한 느낌과 안전감을 제공하고 심적인 불안감을 해소하여 검사에 도움을 줄 수 있기 때문에 임상 적용을 적극 권장하는 바이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.335-335
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• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.25-26
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• 2021

Due to COVID-19, the spread of non-face-to-face culture is increasing the time spent indoors. Accordingly, it is necessary to reduce indoor air pollutants. Also, among building materials, there are paints. As the number of coatings increases, the coating film becomes thick, and there is a risk of cracking and falling off. Therefore, this study is to examine the adsorption properties of indoor air pollutants according to the number of coatings of a paint mixed with powdered activated carbon. In the experimental plan, the addition ratio of powdered activated carbon was selected as 30%, and the number of coatings was selected as primcoating, second coat, and finishing coat, and the concentration of formaldehyde and volatile organic compounds were measured. As a result, as the number of coatings increased, the concentration of formaldehyde and volatile organic compounds tended to decrease. This is considered to be due to the fact that not only the physical adsorption acted by the internal pores of the powdered activated carbon, but also because a lot of powdered activated carbon was present on the painted surface as the coating film was formed. However, since it is judged that there is an error in the concentration due to the inflow of external air as the chamber cover is opened to put the test object in the adsorption test process, it is considered that the experimental method needs to be supplemented.

• 전자공학회논문지
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• 제53권8호
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• pp.76-82
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• 2016

본 논문에서는 근거리장에서 NFS(near field scanning)를 사용한 차폐효율 평가 방법을 통해 CNT(carbon nanotube) 필름의 차폐 특성을 분석하였다. 차폐 특성 평가는 농도 5%와 1mm의 두께를 가지는 CNT 필름과 실제 IC package를 모사한 테스트쿠폰을 사용하여 CNT 필름과 테스트쿠폰과의 거리에 따른 전자파 차폐효율 및 측정 위치에 따른 차폐효율을 측정하였다. 그 결과 근거리장에서 측정된 차폐효율은 주파수에 따라 차폐효율이 달랐다. 테스트쿠폰의 중심에서 측정된 전기장 차폐효율은 fringing effect의 영향을 받는 패턴경계보다 전기장 차폐효율이 좋은 것으로 측정되었다. 이는 근거리장에서 측정된 차폐효율은 주파수뿐만 아니라 CNT 필름과 측정 프로브의 높이, 측정 위치와 같은 측정 환경에 영향을 받는 것을 보여준다. 결론적으로 근거리장에서 제안된 방법을 사용하여 측정한 차폐효율과 ASTM D 4935-10에 의해 측정된 차폐효율은 연관성을 찾기 어렵기 때문에 전장 시스템의 거리 영역에 따라 적절한 측정 방법을 고려하여 측정해야 한다.