Preparation of micro-coiled SiC and TiC fibres by vapour phase metallizing of micro-coiled carbon fibres

Motojima, Seiji; Kagiya, S.; Iwanaga, Hiroshi

doi:10.1007/bf00366364

Cited by 12 publications

(3 citation statements)

References 13 publications

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“…Among currently available industrial raw materials those with a micro-coiled or helical morphology are not available. At present, research is not only active in the area of 'coiled carbon fiber' but also on coiled inorganic whiskers, for example SiC, TiC, Si 3 N 4 etc [3,4]. However, their growth mechanism has not been well defined.…”

Section: Introductionmentioning

confidence: 99%

Development and characterization of micro-coil carbon fibers by a microwave CVD system

Varadan

Hollinger²,

Xie

et al. 2000

Smart Mater. Struct.

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Nano-and micro-coiled carbon fibers find applications in electronic devices, electromagnetic absorbers and filters. Smart devices can be conceived using tunable films on these fibers and tunable host materials. A new method of producing helical carbon fibers with dimensions in the order of less than a micrometer has been developed using microwaves. The microwave CVD system presented here eliminates the use of the toxic impurity gas, which is required in the conventional method. Both methods involve gas phase reactions over a substrate seeded with an appropriate catalyst. Micro-coiled carbon fiber (MCCF) was grown by the catalytic pyrolysis of acetylene on a silicon carbide substrate on which nickel metal powder was dispersed as a catalyst. Various factors, for example flow rate of the gas, particle size of the catalyst, effect of reaction temperature and time, were studied in order to understand the growth of the microwave synthesis of MCCF. MCCFs were also synthesized by a conventional method in the presence of thiophene as an impurity gas so that a comparison can be made with the materials obtained by the microwave system. The morphology of the final products were investigated by scanning electron microscopy. The carbon products obtained by traditional and microwave methods were investigated with the help of x-ray diffraction. The effect of various reaction conditions on the morphological development of a MCCF were examined in detail. Furthermore, a brief study was made on the microwave absorbing property of the MCCF.

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Section: Introductionmentioning

confidence: 99%

Development and characterization of micro-coil carbon fibers by a microwave CVD system

Varadan

Hollinger²,

Xie

et al. 2000

Smart Mater. Struct.

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“…They have much similarity with the structure of living body and with wave-motions. Since efficient preparation technology was developed by Motojima [7][8][9][10][11][12], many novel properties such as elasticity, EM wave absorbing property, sensor property and surface property have been explored [13][14][15][16][17]. In order to put carbon micro/nano-coils into numerous applications including EM wave absorbers, microsensors, nanomechanical devices and advanced composite materials, it is very necessary to prepare carbon coils in different sharp and size controllably.…”

Section: Introductionmentioning

confidence: 99%

Vapor Phase Growth of Carbon Microcoils / Nanocoils

Yang

Chen

Motojima

2005

JMNM

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The carbon microcoils and carbon nanocoils were prepared by the catalytic pyrolysis of acetylene under the Ni and/or Fe-containing catalysts, and the growth pattern, morphology and growth mechanism of the carbon coils were examined in detail. The inner coil diameter of carbon microcoils are of several µm and coil gap from zero to several µm. The inner coil diameter of carbon nanocoils are from zero to several ten nm and coil gap from zero to several nm. The carbon microcoils are generally of double helix coils such as DNA while carbon nanocoils were single helix coils such as α-helix proteins, with spring-like or twisted forms. A catalyst grain was usually observed on the tip of carbon coil. The carbon nanocoils are almost amorphous and can be graphitized by the high temperature heat-treatment.

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“…We have obtained regularly microcoiled carbon fibers (referred to as "carbon coils" hereafter) with high reproducibility by the catalytic pyrolysis of acetylene. 17-26 Furthermore, we have obtained various ceramic microcoils, such as SiC, 27 TiC, 19,27 and ZrC, 28 by vapor phase metallizing of the carbon coils with full preservation of the coiling morphology. The microcoiled fibers or microtubes of metal carbides and nitrides may be potential candidates for conductive fillers, reinforcing fibers, electromagnetic shielding materials or absorbers, microsensors, etc.In this work, TiN microcoils or microtubes were prepared by vapor phase nitriding of TiC microcoils (indirect process) and direct titanizing/nitriding of carbon microcoils (direct process).…”

mentioning

confidence: 99%

Preparation of TiN Microcoils and Microtubes by Titanizing/Nitriding of Carbon and TiC Microcoils

Motojima¹,

Hwang²,

Chen³

et al. 2000

J. Electrochem. Soc.

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Materials with a three-dimensional (3D) microcoiled structure or with a microtube morphology are not industrially available. However, we could expect novel properties from the microcoiled materials which have morphologies similar to DNA or from a microtube morphology. The growth of microcoiled carbon fibers from the vapor phase has been reported by many researchers. [1][2][3][4][5][6][7][8][9] The vapor growth of the microcoils of SiC, [10][11][12] Si 3 N 4 , [13][14][15][16] etc. have also been reported. However, the growth of such coiled fibers was accidental and poorly reproducible. We have obtained regularly microcoiled carbon fibers (referred to as "carbon coils" hereafter) with high reproducibility by the catalytic pyrolysis of acetylene. 17-26 Furthermore, we have obtained various ceramic microcoils, such as SiC, 27 TiC, 19,27 and ZrC, 28 by vapor phase metallizing of the carbon coils with full preservation of the coiling morphology. The microcoiled fibers or microtubes of metal carbides and nitrides may be potential candidates for conductive fillers, reinforcing fibers, electromagnetic shielding materials or absorbers, microsensors, etc.In this work, TiN microcoils or microtubes were prepared by vapor phase nitriding of TiC microcoils (indirect process) and direct titanizing/nitriding of carbon microcoils (direct process). The preparation conditions and some properties were also determined. ExperimentalPreparation of source carbon coils.-The source carbon coils were prepared by the Ni-catalyzed pyrolysis of acetylene. A horizontal quartz tube (60 mm i.d.) was used as the reaction tube. The gas mixture of acetylene containing a small amount of thiophene as an impurity, hydrogen, and nitrogen were introduced into the reaction tube from an upper gas inlet and exhausted from a lower outlet. A graphite plate, on which Ni powder (about 5 m diam) was dispersed, was used as a substrate. Reaction temperature, reaction time, and total reaction gas pressure were fixed at 750ЊC, 2 h, and 1 atm, respectively. The obtained carbon coils have a coil diameter of 3-5 m, coil pitch of 0.3-2 m, and a coil length of 1-5 mm.

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Preparation of micro-coiled SiC and TiC fibres by vapour phase metallizing of micro-coiled carbon fibres

Cited by 12 publications

References 13 publications

Development and characterization of micro-coil carbon fibers by a microwave CVD system

Development and characterization of micro-coil carbon fibers by a microwave CVD system

Vapor Phase Growth of Carbon Microcoils / Nanocoils

Preparation of TiN Microcoils and Microtubes by Titanizing/Nitriding of Carbon and TiC Microcoils

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