• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.1
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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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• v.44 no.6
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• pp.563-571
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• 2006

Vapor grown carbon fiber (VGCF) nano-materials such as carbon nanotubes and carbon nanofibers were directly grown on the surface of the stainless steel mesh pre-treated by reduction. The reduction of the stainless steel mesh by hydrogen formed small catalytic particles and large particles with bi-modal distribution on the metal surface. When the VGCFs were synthesized on the reduced mesh, carbon nanotubes (CNTs) were dominantly grown from the small catalytic particles without supplying hydrogen gas. However, carbon nanofibers (CNFs) were dominantly grown from the large catalytic particles with hydrogen.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.5
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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.

• Korean Journal of Materials Research
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• v.16 no.1
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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.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.4
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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.

• Journal of the Korean Ceramic Society
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• v.41 no.12 s.271
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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.

• Polymer(Korea)
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• v.31 no.2
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• pp.117-122
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• 2007

In this work, the mechanical and electrical properties, and thermal stability of vapor-grown carbon nanofibers/polyimide (VGCNFs/PI) composite film synthesized by in-situ polymerization were investigated in terms of tensile properties, volume resistivity and thermogravimetric analysis (TGA), respectively. From the results, the addition of VGCNFs with a certain amount into polyimide led to obvious improvement in tensile strength. The volume resistivity of the films was decreased with increasing the VGCNFs content and the electrical percolation threshold appeared between 1 and 3 wt% of VGCNFs content, which was probably caused by the formation of interconnective structures among the VGCNFs in a composite system. The thermal stability of the film was higher than that of pure PI one. This result indicated that the crosslinking of VGCNFs/PI Composites was enhanced by well-distribution of YGCNFs in PI resin, resulting in the increase of the thermal stability of the resulting composites.

• Polymer(Korea)
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• v.29 no.5
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• pp.481-485
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• 2005

In this work, the thermal and mechanical properties of vapor grown carbon nanofibers (VGCNFs)-reinforced difunctional epoxy (EP) composites were investigated in the presence of the 0, 0.1, 0.5, 1.0, and $2wt\%$ VGCNFs. The thermal properties of the VGCNFs/EP composites were studied by thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA). The mechanical properties of the VGCNFs/EP composites were also examined by universal testing machine (UTM), falling impact test, and the friction and wear tests. From experimental results, the thermal and mechanical properties of the VGCNFs/EP composites were improved with increasing the VGCNFs contents. This was due to the increase of crosslinking structure of the composites, resulting in improving the mechanical interlockings between VGCNFs and epoxy resins in the present composite system.

• Journal of the Semiconductor & Display Technology
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• v.3 no.1
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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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• v.18 no.3
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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.