A REVIEW ON CARBON NANO -TUBES PRODUCTION AND ITS
MECHANICAL PROPERTIES
1
Prakash Kumar Sen1, Shailendra Kumar Bohidar2 ,Chandan Sharma3, Vivek modi4 , Yagyanarayan Shrivas5,
1, 2
3, 4, 5
Faculty, Kirodimal institute of Technology, Raigarh, Chhattisgarh, India
Student, Bachelor of Engg.,Kirodimal Institute of Technology, Raigarh,Chhattisgarh,India
nanometers (approximately 50,000 times smaller than the
width of a length.
Abstract-The present paper give the survey of carbon
nanotube technology through this paper an attempt has been
made to visualize the carbon nanotube technology. Carbon
nanotubes, popularly known as CNTs are molecular-scale
tubes of graphitic carbon with outstanding properties. Carbon
atoms in a carbon nanotube have a graphitic structure. The
tubes can therefore be considered as rolled-up graphite sheets.
The strength of the carbon-carbon bonds provides very high
strength and modulus. The Young's modulus of the best
Nanotubes can be as high as 1000 GPa, approximately 5 times
higher than steel. The tensile strength of Nanotubes can be up
to 65 GPa, around 50 times higher than steel. They also possess
remarkably high electrical and thermal properties.
Index Terms- Carbon Nanotubes, Tensile strength, Young’s
Modulus.
I.
INTRODUCTION
Carbon nanotubes (CNTs) are tubular cylinders of carbon
atoms that have extraordinary mechanical, electrical,
thermal, optical and chemical properties At the individual
tube level, these unique structures exhibit: 200X the strength
and 5X the elasticity of steel; 5X the electrical conductivity
("ballistic transport"), 15X the thermal conductivity and
1,000X the current capacity of copper; at almost half the
density of aluminium. As a carbon based product, CNTs
have almost none of environmental or physical degradation
issues common to metals—thermal expansion and
contraction, corrosion and sensitivity to radiation all of
which result in greater system failure in performancesensitive applications. This article considers the mechanical
properties of carbon nanotubes.
Carbon nanotubes (CNTs) are allotropes of carbon. A
carbon nanotube is a one-atom thick sheet of graphite
(graphene) rolled up into a seamless cylinder with diameter
of the order of a nanometre. This results in a nanostructure
where the length-to-diameter ratio exceeds 10,000. Such
cylindrical carbon molecules have novel properties that
make them potentially useful in a wide variety of
applications in mechanical, structural, thermal, electrical &
electronics, optical, biomedical and other fields of science,
engineering & medicine. They exhibit extraordinary
strength and unique electrical properties, and are efficient
conductors of heat. Their name is de-rived from their size,
since the diameter of a nanotube is on the order of a few
The first noticeable discovery of carbon nanotubes was
reported by Ilijima [1] in 1991, when he found layers of
carbo (graphene) rolled into tubular structure in the soot of
arc discharge method. The nanotubes consisted of up to
several tens of graphitic shells (so called multi-walled
carbon nanotubes (MWNT)) with adjacent shell separation
of 0.34 nm, diameters of 1 nm and high length/diameter
ratio. Ili-jima’s discovery of carbon nanotubes in the
insoluble material of arc-burned graphite rods created the
buzz that greatly accelerated work on synthesis, production
and properties of carbon nanotubes. It took two more years
for Iijima and Ichihashi at NEC [2], and Bethune et al. [3] at
IBM to synthesize SWNT by addition of transition metal
catalysts to carbon in an arc discharge in 1993. Significant
contributions to the race for devising method for production
of carbon nanotubes were made by la-ser-ablation synthesis
of bundles of aligned SWNT with small diameter
distribution by Smalley and co- workers at Rice University
in 1995 [4] and by catalytic growth of nanotubes by the
chemical vapor decomposition (CVD) method by Yacaman
et al. [5]
II. LITERATURE REVIEW ON CARBON
NANOTUBES
The Carbon nanotubes (CNT) with carbon atoms, having
diameter of nano meter order, and length is in micrometers.
According to Qian D. et al. (2002)[6] explained exciting
statements about CNTs.
 “CNT is 100 times stronger than stainless steel and six
times lighter...”
 “CNT is as hard as diamond and its thermal capacity is
twice that of pure diamond...”
 “CNT’s current-carrying capacity is 1000 times higher
than that of copper...”

“CNT is thermally stable up to 4000K...”
 “CNT can be metallic or semiconducting, depending on
their diameter and chirality...”.
Carbon nanotubes are the broad area, it can be used
to produce nano composites Several research on mechanical
properties on CNTs have been done, recent study on wear
behaviour on CNT- Al nano composite have been done by
U. Abdullahi et al.[7] According to which The composite
were fabricated using pure aluminium (Al) (99.7%), with
particle size of 78 μm which has nearly spherical shape with
2
some satellite sub-particles obtained from Innovative
Pultrusion Sdn Bhd, a local supplier for the aluminium
powder was used as a matrix material. The multi walled
carbon nano tubes (MWCNTs) with a nominal diameter of
10 nm, length of 5-15 μm, and surface area of 230-280 m2g1 was also obtained from the same supplier in Malaysia and
used as a reinforcement. Ethanol was used as a process
control agent (PCA) during the ball milling of CNT and Al
powders. And the result of wear behaviour shows that CNTs
Al nano composite shows lower wear rate than pure
aluminium and wear rate of all the tested materials increases
with increase in normal applied load. Wear rate decrease
with increase in CNTs content from 0-1.5 wt% and increase
slightly from 1.5-2 wt%, then increase rapidly after this
range of CNT content. A distinctive abrasive and adhesive
wear were observed from the morphological image of the
worn surface. Hardness increases with increase in CNTs
content from 0-1.5 wt% and decreased gradually from 2.0
wt%. Wear resistance increase also within the range of 0-1.5
wt% CNT and decrease subsequently with increasing of
CNT content.
Smith and Luzzi. 2000 et al.[8] Although various
fullerenes can be produced using different ways of
vaporizing carbon followed by condensation of the tiny
clusters, the presence of an electric field in the arc discharge
seems to promote the growth of the long tubules. In
addition, a small amount of transition metal powder (i.e.
cobalt, nickel, or iron) seems to favor growth of SWNTs.
Here the metal clearly serves as a catalyst, preventing the
growing tubular structurefrom wrapping around and closing
into a smaller fullerene cage. The presence of the catalyst
also allows one to lower the operating temperature. The
carbon atoms in an NT, neglecting the ends, have 99.4% of
the cohesive energy that they would have in perfect
crystalline graphite. This is far better than the amount of
cohesive energy that would be found in C60. If feeding a
cheap hydrocarbon such as ethylene to the NT ever becomes
possible, buckyropes will grow, and grow inexpensively in
industrial laboratories.
Fig 1 Show double wall CNTs
Fig.2 shows multiwall CNTs
III. MANUFACTURING METHODS OF CARBON
NANOTUBES
Carbon nano-tubes are very difficult to manufacture
although there are several methods Like arc discharge,
chemical vapour deposition, laser ablation, flame synthesis,
high pressure carbon monoxide (HiPco), electrolysis, which
uses different chemical , physical and electrical properties
to manufacture the same, which can be summerized by the
given figure.
Fig.3 Showing the classification of techniques of
manufacturing CNTs
These all the classification can be understood in three basic
broad area which are as follows:1.
2.
3.
Physical process
Chemical process
Miscellaneous process
A. PHYSICAL PROCESS
Muhammad Musaddique Ali Rafique et al. [9] They are the
processes, which makes the use of physical principles of
carbon that convert it into nanotubes. Arc discharge and
laser ablation are some of the technics under these. They are
popular process of carbon nanotubes production. Due to
their wide spread popularity they are by far the most widely
3
used processes for nanotubes production for experimental
purposes.
 ARC DISCHARGE METHOD
This is one of the oldest methods of carbon nanotube
production. First utilized by Iijima [1] in 1991 at NEC’s
Fundamental Research Laboratory to produce new type of
finite carbon structures consisting of needle-like tubes. The
tubes were produced using an arc discharge evaporation
method similar to that used for the fullerene synthesis. The
carbon needles, ranging from 4 to 30 nm in diameter and up
to 1 mm in length, were grown on the negative end of the
carbon electrode used for the direct current (DC) arcdischarge evaporation of carbon. During the process Iijima
used a pressurized chamber filled with a gas mixture of 10
Torr methane and 40 Torr argon. Two vertical thin
electrodes were installed in the center of the chamber
(Figure 3.1.1). The lower electrode (cathode) contained a
small piece of iron in a shallow dip made purposefully to
hold iron.
 LASER ABLATION PROCESS
In the laser ablation process, a pulse laser is made to
strike at graphite target in a high temperature reactor in the
presence of inert gas such as helium which vaporizes a
graphite target. The nanotubes develop on the cooler
surfaces of the reactor, as the vaporized carbon condenses.
A water-cooled surface is also included in the most practical
systems to collect the nanotubes (Fig.5)
Fig.5. Showing laser Ablation Process
Fig.4. Arc discharge method for production of CNTs
The arc was generated by running a DC current of 200A
at 20V between the electrodes. The use of the three
components, namely argon, iron and methane, was critical
for the synthesis of SWNT. Carbon soot produced as result
of arc-discharge settled and nanotubes grew on the iron
catalysts contained in negative cathode. The nano-tubes had
diameters of 1 nm with a broad diameter distribution
between 0.7 and 1.65 nm. In a similar process Bethune et al.
used thin electrodes with bored holes as anodes, which were
filled with a mixture of pure powdered metals (Fe, Ni or Co)
(catalysts) and graphite. The electrodes were vaporized with
a current of 95 - 105 A in 100 - 500 Torr of Helium. SWNT
were also produced by the variant of arc-technique by
Journet et al. [10] as well. In his variant, the arc was
generated between two graphite electrodes in a reaction
chamber under helium atmosphere (660 mbar). This method
also gave large yield of carbon nanotubes. Ebbesen and
Ajayan, [11] however, reported large-scale synthesis of
MWNT by a variant of the standard arc discharge technique
as well.
This method was first discovered by Smally and coworkers at Rive University in 1995 [4]. At the time of
discovery they were studying the effect of laser impingment
on metals. They produced high yields (>70%) of Single
walled Carbon Nanotubes by laser ablation of graphite rods
containing small amounts of Ni and Co at 1200°C. In this
method two-step laser ablation was used. Initial laser
vaporization pulse was followed by second pulse to vaporise
target more rapidly. The two step process minimizes the
amount of carbon deposited as soot. Tubes grow in this
method on catalysts atoms and continued to grow many
catalyst atoms aggregate at the end of the tube. The tubes
produced by this method are in the form of mat of ropes 10 20 nm in diameter and up to 100 micron or more in length.
By varying temperature, catalyst composition and other
process parameters average diameter and length of car-bon
nanotube could be varied.
B. CHEMICAL PROCESS

Chemical Vapour Deposition
Chemical vapour deposition (CVD) is the best
technique to synthesize CNTs. Rajesh Purohit et al.[12]
according to his study In this method, the decomposition of
the carbon precursor & CNT formation take place on the
surface of catalyst particles. The two most important CVD
techniques for synthesis of CNT are the thermal CVD &
plasma enhanced CVD (PECVD). CNTs can be produced at
relatively low temperatures and their size can be controlled
by varying the size of catalyst particles. CVD is used for the
large scale production of CNTs. It is achieved by taking a
carbon source in the gas phase & using an energy source,
such a resistively heated coil, to impart energy to a gaseous
carbon molecule. Commonly used carbon sources include
4
methane, carbon monoxide, acetylene etc. This will result in
the formation of CNTs, if the proper parameters are
maintained. The CNT synthesis using CVD is essentially a
two steps process. A catalyst preparation step is the first step
followed by actual synthesis of nanotube. The catalyst is
generally prepared by sputtering, physical vapour deposition
(PVD), dip coating etc. The next step is heating up the
substrate in a carbon rich gaseous environment.
Temperature for the synthesis of nanotubes in this technique
is generally 500 to 1000°C.
When compared with the previous two methods, CVD
is a simple and economic technique for synthesizing CNTs
at relatively low temperature and ambient pressure, but at
the cost of crystallinity. It is a versatile process as it
harnesses a variety of hydrocarbons in any state (solid,
liquid or gas), enables the use of various substrates and
allows CNT growths in a variety of forms, such as powder,
thin or thick films, aligned or entangled, straight or coiled,
or even a desired architecture of nanotubes at predefined
sites on a patterned substrate. It also offers better control
over growth parameters. Fig.6
diameter. Hence, metal nanoparticles of controlled size can
be used to grow CNTs of controlled diameter. Thin films of
catalyst coated onto various substrates have also been
proved successful in achieving uniform CNT deposits. In
addition, the material, morphology and textural properties of
the substrate greatly affect the yield and quality of the
resulting CNTs.
Fig.6. Scheme of chemical vapour deposition method for
production of CNTs
Fig. shows a schematic diagram of the setup used
for CNT growth by CVD in its simplest form. The process
involves passing a hydrocarbon vapour (typically for 15-60
minutes) through a tube furnace in which a catalyst material
is present at sufficiently high temperature (600-1200°C) to
decompose the hydrocarbon.
CNTs grow over the catalyst and are collected when the
system is cooled to room temperature. When a liquid
hydrocarbon (benzene, alcohol, etc.) is being employed, it is
heated in a flask and an inert gas is purged through it to
carry the vapour into the reaction furnace. The design of the
CVD reactor depends on whether the carbon precursors are
liquid or gas. Liquid carbon precursors often use a bubbler
to vaporize the reactants, and a carrier gas (reactive gases
such as H2 or inert gas such as N2 or Ar) to transport the
vaporized reactants into the CVD reactor. The three main
parameters which affect CNT growth in CVD are the
hydrocarbon, catalyst and growth temperature. Generally,
low-temperature CVD (600-900°C) yields MWNTs,
whereas a higher temperature (900 1200°C) reaction favors
SWNT growth, indicating that SWNTs have a higher energy
of formation, probably owing to their small diameters,
which results in high curvature and high strain energy. The
catalyst particle size has been found to dictate the nanotube
V. CONCLUSION
IV. ESSENTIAL PROPERTIES OF CNTs
On the basis of study on above different techniques for
production of CNTs, it is observed that
 The arc discharge method and laser ablation method
are having difficulty in availability of raw material
where as chemical vapour deposition are having
abundantly availability of raw material.
 Energy requirement in arc discharge and laser ablation
are high where as chemical vapour deposition is
moderate.
 It is difficult to control the process in arc discharge and
laser ablation where as in chemical vapour depotion it
is easy due to full automation.
 The design aspect of arc discharge and laser ablation
are quite complicated where as in chemical deposition
reactor can be made as much large as possible.
 Production rate of arc discharge and laser ablation
comparatively lower than chemical vapour deposition.
 There is no prior requirement of refining
treatment(post treatment) in chemical vapour
deposition whereas, required by arc discharge and laser
ablation.[12]
On discussion part after this study several conclusions
were made, The Significant improvement in current stage of
electronics can be achieved, if the proper growth parameters
could be regulated for the production of CNTs. In the
relative phenomena’s of CNT, its mechanical properties and
unique electronic properties make them both interesting as
well as potentially very useful in future technologies. Both
the laser ablation technology method and arc discharge
technology method surfer from the disadvantages of being
highly expensive and costly and un-economical methods of
production of carbon nano-tubes on large scale, despite they
yield high quality carbon nanotubes with reasonable high
yield. In this process the Chemical Vapour Deposition can
be considered as economical method of production of high
purity Single Walled Carbon Nanotubes (SWNT) on large
scale. Significant improvement in current stage of
electronics can be achieved, if the proper growth parameters
could be regulated for the production of CNT. CNTs
possess exceptionally high stiffness, strength and resilience,
as well as superior electrical and thermal properties, which
makes it the ultimate reinforcing material for the nano
Composites.
5
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