Construction of apparatus for production of carbon nanotubes (CNTs)
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Date
2015
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Carbon nanotubes (CNTs) are rolled up cylinders of graphene sheets [1]. There are two main types of
of carbon nanotubes, namely, multi-walled carbon nanotubes (MWCNTs) and single-walled carbon
nanotubes (SWCNTs) [2]. The unique nearly one dimensional structure of CNTs results in many
attractive properties, which has led to many interesting applications. There are mainly three major
techniques to produce CNTs. They are arc discharge, chemical vapor deposition (CCVD) and laser
ablation. Though scientists are researching more economic ways to produce these structures, CNTs
produced using different techniques have different properties. Due to inexpensiveness and being able
to perform even in open air, arc-discharge technique has attracted attention in the production of CNT.
In arc discharge, a vapor is created by an arc discharge between two carbon electrodes with or without
a catalyst. Nanotubes self-assemble from the resulting carbon vapor. Both SWCNT and MWCNTs
can easily be obtained by this technique simply by with or without the inclusion of a metal catalyst
particle into anode. However, although arc-discharge produces large quantity of CNTs, the product is
contaminated with other carbon materials, hence requiring lots of purification. Further nanotubes tend
to be short with random sizes and direction when produced via arc-discharge route. In this work, we
describe the development of apparatus for arc-discharge to produce CNTs using carbon electrodes
made using high purity a rare variety of natural vein graphite.
Methodology
In order to produce carbon nanotubes, the first step is the construction of arc-discharging set-up. Here
we describe the construction of an arc-discharge unit at UWU using home-built parts. The Instrument
consists of mainly three parts. First part is the vacuum chamber. Second parts are the cathode and
anode holders. Anode holder is fixed in position and the cathode holder can move up and down (or
back and forth) by using a stepper motor. Another main part is the control unit. Control unit controls
the steeper motor which drives the two electrodes in a controlled manner inside the vacuum. Next
important step is the preparation of rod shaped graphite from > 99% pure as-received vain graphite
lumps followed by purification of carbon nanotubes and characterizing those using suitable techniques
such as SEM, TEM and Raman.
Description
Keywords
Science and Technology, Technology, Mineral Sciences, Rubber Production, Materials Sciences