Synthesis of Narrow Diameter Multiwalled Carbon Nanotubes (MWNTs) By Catalytic Chemical Vapor Deposition For Mechanical Reinforcement Applications

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Strong and versatile carbon nanotubes (CNTs) are finding new applications in improving conventional polymer-based fibers. Nanotube-reinforced composites could ultimately provide the foundation for a new class of strong and lightweight fibers with properties such as electrical and thermal conductivity unavailable in current fibers. A recent research has discovered that the best type of nanotube for polymer composite reinforcement is the small diameter multiwalled nanotubes (MWNTs). One serious weakness of all current techniques for preparing MWNTs is that they produce a wide range of tube sizes and structures, which could be a drawback in areas where specific tube structures are needed. Here, a catalytic technique has been developed to produce narrow diameter bulk multiwalled carbon nanotubes in the range of 19 to 38 nm. The method involved catalytic decomposition of methane over the catalyst at 950°C in a chemical vapour deposition system. It includes pre-treatment of iron, nickel and cobalt catalyst with NH3 gas as the key step to produce CNTs with specific structure. Structural characterizations including scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis and Raman spectroscopy conducted on CNTs grown on three different catalysts, namely iron, cobalt and nickel have indicated that the catalyst used affects their sizes and crystallinity.

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Journal: TechConnect Briefs
Volume: 1, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: May 7, 2006
Pages: 125 - 128
Industry sector: Advanced Materials & Manufacturing
Topic: Carbon Nano Structures & Devices
ISBN: 0-9767985-6-5