G. H. PATEL COLLEGE OF ENGINEERING AND TECHNOLOGY

WELCOME

• Presented by

• 130110107054 SHUKLA DEVANSHI

• 130110107055 CHIRAG SONAGRA

FABRICATION OF CARBON NANOTUBES

CONTENTS

Electric arc method

Chemical vapour deposition method

Pulsed laser deposition

Mcqs

• Produces best quality of nanotubes.

• Most common, the easiest and simple way to produce CNTs.

• It’s also known as plasma arching method or DC arc discharging

method.

ELECTRIC ARC METHOD

FIGURE

DESCRIPTION AND WORKING

• The set up consists of pair of carbon electrodes in an atmosphere

of helium gas under a pressure of 100 to 500 torr inside an

evaluated chamber.

• The diameter of electrodes used should be between 5 to 20 mm.

• A direct current of 50 to120Adriven by an external dc voltage

supply of 20 to 25V is applied between the electrodes.

COUNT……

• When the dc voltage supply is switched on, an arc is produced passing

from one electrode (anode) to another electrode(cathode). Thus, carbon

atoms are ejected from anode and get deposited on cathode forming

nanotubes.

• The central region of cathode reaches a temperature close to 3000⁰C.

nanotubes are found to be deposited in the central region of cathode. A

necessary cooling arrangement is made to control the temperature inside

the chamber. Nanotubes with a diameter from 2 to 30 mm and 1 µm length

can be produced by this method.

• To produce MWCNT’s it is not necessary to use any catalyst.

• To produce SWCNT’s it is necessary to use a catalyst added to the

anode.

• Fe, Co, Ni or some other metals can be used as catalyst.

• It involves decomposing a hydrocarbon gas such as methane at 1100⁰C

or ethane etc.

• For large scale production of carbon fibers and filaments, this method

is useful.

CHEMICAL VAPOUR DEPOSITION METHOD

FIGURE

DESCRIPTION AND WORKING

• It consists of a high temperature evacuated reaction vacuum

furnace. The vacuum is produced inside the furnace with the help

of a vacuum pump connected to the furnace. There is also a

provision to maintain inert atmosphere. Inside the furnace, a

substrate prepared with a layer of metal catalyst such Fe, Co or Ni

is placed.

COUNT.....

• There is also an another provision in the furnace to allow two types of

gases to initiate the growth of CNT’s. one type of gas is a process gas

like NH3 , N2, H2 etc. and the other a carbon containing gas such as

methane, ethane, acetylene, ethylene, etc.

COUNT……

• The hydrocarbon gas such as methane is passed into the furnace. The

furnace is heated to approximately 750⁰C to 1100⁰C , based on the

selection of hydrocarbon. At this high temperature, the gas decomposes

producing carbon atoms which get deposited over the catalytic substrate

forming nanotubes. The catalyst a very important role in CNT formation.

• This method of production allows continuous fabrication of nanotubes

with open ends which doesn’t occur in other method.

MERITS

• Both SWCNT and MWCNT’s are possible to obtain this method.

• High purity CNTs can be produced due to the non formation of

nanoparticles or amorphous carbon.

• Aligned CNTs can be deposited over the solid substrate which has

major application in electronics field.

PULSED LASER DEPOSITION

With the help of pulsed laser beam, SWCNT’s can be prepared

by laser vapourisation of a graphite rod

DESCRIPTION

• The schematic sketch of the pulsed laser deposition set-up shown in fig.

• The apparatus consists of a quartz tube filled with Ar gas under a

pressure of 500 torr.

• A graphite target doped with small amount of catalyst like Co, Fe or Ni

to act as catalyst nucleation sites for the formation of CNT is also placed

inside the quartz tube.

• The quartz tube containing the Ar gas and a graphite target is heated to

1200 ˚C.

• Inside the quartz the tube a water cooled copper collector is placed at

the other end just away from the furnace.

FIGURE

WORKING

• When a highly intense pulsed laser beam produced from a Nd:YAG laser source is

incident on the target, it evaporates carbon from the target graphite.

• The Ar gas sweeps the evaporated carbon atoms from the high temperature zone to

the low temperature zone ( i.e. towards the cooled copper collector )where they

condense into nanotubes.

• In this method, the dual pulsed laser beam minimises the amount of carbon

deposited as soot.

• The initial laser vapourisation pulse is followed by a second pulse to vapourise the

target more uniformly. the second laser pulse particles ablated by the first one and

feeds them into the growing nanotube structure.

MERITS

• In this method, CNT ropes of 10-20 nm in diameter with a length

of 100 nm can be produced. the tube diameter can be controlled

by the reaction temperature. More than 85% of graphite is

converted into CNTs.

1. ______ method produces best quality of nanotubes???

A. Electric Arc B. Chemical Vapour Deposition C. Pulsed Laser Deposition D. All

2. The atmosphere of ______ gas is provide in electric arc method.

A. Ar B. He C. Ne D. Xe

3. The pressure( in torr) of which magnitude is provided in electric arc method???

A. 10 to 500 B. 100 to 500 C.200 to 250 D. 100 to 400

4. The voltage of which magnitude is provided in electric arc method???

A. 10 to 25 V B. 20 to 25 V C. 20 to 30 V D. 10 to 15 V

5. Which diameter of Nanotubes from in electric arc method???

A. 5 to 20 B. 2 to 15 C. 10 – 20 D. 2 to 30

Mcqs

6. Which method is use to product the large scale of carbon fibres ???

A. VPD B. DCAD C. Pulsed laser Deposition D. A & B both

7. What is the range of temperature in Chemical Vapour Deposition Method to

heat the furnace???

A. 750 to 1200˚C C. B. 1200˚C C. 750 to 1100˚C D. 1100 to 1200˚C

8. Which gas is used in Pulsed Laser Deposition???

A. He B. Ar C. Kr D. Xe

9. The pressure (in torr) of which magnitude is provided in Pulsed Laser

Deposition???

A. 300 B. 100 to 500 C. 500 D. 100

10. What is the length of carbon nanotubes in electric arc method ???

A. 1nm B. 1µm C. 2nm D. None of this

THANK YOU…