• 한국결정성장학회지
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• 제14권1호
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• pp.1-5
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• 2004

Carbon nanofilaments were formed on silicon substrate via microwave plasma-enhanced chemical vapor deposition method. The structure of carbon nanofilaments was identified as the carbon nanofibers. The extent of carbon nanofibers growth and the diameters of carbon nanofibers increased with increasing the total pressure. The growth direction of carbon nanofibers was horizontal to the substrate. Laterally grown carbon nanofibers showed the semiconductor electrical characteristics.

• Korean Chemical Engineering Research
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• 제44권6호
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• pp.563-571
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• 2006

스테인리스 스틸 메쉬 표면을 환원 전처리하여 그 표면상에 직접 탄소나노튜브 또는 탄소나노섬유와 같은 VGCF (vapor grown carbon fiber) 나노물질을 합성 성장시켰다. 수소 가스를 이용하여 스테인리스 스틸 메쉬를 환원 처리함으로써, 금속 표면상에 bi-modal 분포의 작은 촉매입자와 큰 촉매입자들이 함께 생성되었다. 환원된 스테인리스 스틸 메쉬로부터 VGCF의 합성 시, 수소 가스가 공급되지 않은 경우는 작은 촉매입자로부터 탄소나노튜브들이 주로 성장되었으나, 특정 량의 수소 가스가 공급될 경우 큰 촉매입자로부터 탄소나노섬유들이 주로 성장되었다.

• 한국결정성장학회지
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• 제16권5호
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• pp.198-202
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• 2006

We could achieve the bridge-type formation of the iridium-catalyzed carbon nanofibers across the gap on the MgO substrate using microwave plasma enhanced chemical vapor deposition method. On the plane surface area of the MgO substrate, the iridium-catalyzed carbon nanofibers were grown as a lateral direction to the substrate. The bridge-type formation and/or the lateral growth of the iridium-catalyzed carbon nanofibers were interconnected with each other. Finally, they could form an entangled network having the bridge-type formation of the carbon nanofibers across the gap on the substrate and the laterally-grown carbon nanofibers on the plane surface area of the substrate. The entangled network showed the semiconductor electrical characteristics.

• 한국재료학회지
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• 제16권1호
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• pp.25-29
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• 2006

Vertical growth of iridium-catalyzed carbon nanofibers could be selectively grown on the MgO substrate using microwave plasma-enhanced chemical vapor deposition method. Growth positions of the iridium-catalyzed carbon nanofibers on the MgO substrate could be manipulated according to the applied bias voltage. At-150 V, the carbon nanofibers growth was confined only at the corner area of the substrate. Based on these results, we discussed the cause for the confinement of the vertically grown carbon nanofibers on the specific area of the MgO substrate as a function of the applied bias voltage.

• 한국결정성장학회지
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• 제17권4호
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• pp.160-164
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• 2007

Carbon nanofibers were deposited on silicon oxide substrate by thermal chemical vapor deposition method. For the enhancement of the characteristics of carbon nanofibers, the source gases ($C_2H_2,\;H_2$) flows were intentionally manipulated as the cyclic on/off modulation of $C_2H_2$ flow. By the cyclic modulation process during the initial deposition stage, the formation density of carbon nanofibers on the substrate could be much more enhanced. The diameter of as-grown carbon nanofibers was also reduced by the cyclic modulation process. The cause for the variation in the characteristics of carbon nanofibers by the cyclic modulation process was discussed in association with the hydrogen gas etching ability.

• 한국세라믹학회지
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• 제41권12호
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• pp.880-883
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• 2004

Carbon nanofibers could be selectively formed at the groove area of the MgO substrate using microwave plasma-enhanced chemical vapor deposition system. Iridium metal was used as a catalyst layer for the formation of the carbon nanofibers. The growth direction of the carbon nanofibers was vertical to the substrate surface. The selectively grown iridium-catalyzed carbon nanofibers show around $1.8V/{\mu}m$ turn-on voltage and $1.0\;mA/cm^2$ field emission current density at $2.65\;V/{\mu}m$ in the field emission measurement.

• 폴리머
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• 제31권2호
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• pp.117-122
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• 2007

본 연구에서는 제자리 중합에 의해 합성된 기상성장 탄소나노섬유/폴리이미드(VGCNFs/PI) 복합재료 필름의 기계적, 전기적 특성과 열안정성을 만능재료 시험기와 체적저항기, 열중량분석기를 통해 관찰하였다. 그 결과, VGCNFs 일정량 첨가되었을 때 복합재료 필름의 인장강도가 증가한 것을 관찰할 수 있었다. VGCNFs/PI 복합재료 필름의 체적저항 값은 VGCNFs 첨가량이 증가할수록 감소하였으며, 전기적 percolation threshold는 VGCNFs 함량 1과 3 wt% 형성되었는데, 이는 복합재료 내부에서 VGCNFs 상호간 네트워크의 형성으로 인하여 전기적 경로가 만들어졌기 때문이라 판단된다. VGCNFs가 PI 복합재료 필름의 열안정성은 순수한 이미드 필름보다 VGCNFs가 첨가됨에 따라 향상되었으며, 이는 충전제로 사용한 VGCNFs가 PI 수지에 잘 분간됨에 따라 복합재료의 가교화에 영향을 주어 VGCNFs/PI 복합재료 필름의 열안정성이 향상된 것으로 판단된다.

• 폴리머
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• 제29권5호
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• pp.481-485
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• 2005

본 연구에서는 2관능성 에폭시 수지에 기상성장 탄소나노섬유(VGCNFs)를 0, 0.1, 0.5, 1.0 그리고 $2wt\%$ 함량 비로 첨가하여, 제조한 VGCNFs/에폭시 복합재료의 열적 및 기계적 특성을 고찰하고자 하였다. VGCNFs/에폭시 나노복합재료의 열적 특성은 TMA와 DMA로 알아보았으며, 기계적 특성은 만능 시험기와 낙하 충격 시험기 및 마찰$\cdot$마모 시험기를 통하여 관찰하였다. 실험 결과. VGCNFs의 함량이 증가할수록 열적 및 기계적 특성이 향상됨을 확인할 수 있었는데, 이는 현재의 복합재료 시스템에 있어서 VGCNFs와 에폭시 사이의 기계적 얽힘 현상의 향상을 가져오는 복합재료의 가교구조의 증가 때문이라 판단된다.

• 반도체디스플레이기술학회지
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• 제3권1호
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• pp.9-13
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• 2004

Carbon nanofibers (CNFs) with uniform diameter and controlled size were prepared from catalytic decomposition of $\textrm{C}_{2}\textrm{H}_{2}$ with Ni-MgO catalyst treated by mechanochemical (MC) process. The properties of Ni catalyst, such as size, distribution and morphology, can be governed by tuning grinding time in MC process. As a result, size and structure of CNFs can be tailored. The effect of grinding time to the as-grown CNFs was studied. CNFs with diameter from 10-70 nm were synthesized. CNFs with bundle formation sharing one tip and twisted CNFs were also synthesized with catalyst treated by MC process.

• Advanced Composite Materials
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• 제18권3호
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• pp.221-232
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• 2009

The allylamine plasma treatment is used to modify the surface properties of vapor grown carbon fibers (VGCF). It is to improve the interfacial bonding between the VGCF and epoxy matrix. The allylamine plasma process was performed by batch process in a vacuum chamber, using gas injection followed by plasma discharge for the durations of 20, 40 and 60 min. The interdependence of mechanical properties on the VGCF contents, treatment time and interfacial bonding between VGCF/ep was investigated. The interfacial bonding between VGCF and epoxy matrix was observed by scanning electron microscopy (SEM) micrographs of nanocomposites fracture surfaces. The changes in the mechanical properties of VGCF/ep, such as the tensile modulus and strength were discussed. The mechanical properties of allylamine plasma treated (AAPT) VGCF/ep were compared with those of raw VGCF/ep. The tensile strength and modulus of allyamine plasma treated VGCF40 (40 min treatment)/ep demonstrated a higher value than those of other samples. The mechanical properties were increased with the allyamine plasma treatment due to the improved adhesion at VGCF/ep interface. The modification of the carbon nanofibers surface was observed by transmission electron microscopy (TEM). SEM micrographs showed an excellent dispersion of VGCF in epoxy matrix by ultrasonic method.