CARBON NANOTUBE:

A NANO MATERIAL

BY: INDRANEEL MAJUMDAR & ANJANI KUMAR

(5th SEMESTER, MECHANICAL ENGG,PCE RKL).

CONTENTS Introduction Discovery Carbon Nanotubes (CNTs) Types Methods of synthesis Properties Applications Obstacles Conclusion Reference

INTRODUCTION TO NANO TECHNOLOGY

“NANOTECHNOLOGY IS AN ENABLING TECHNOLOGY THAT ALLOWS US TO DEVELOPMATERIALS WITH IMPROVED OR TOTALLY NEW

PROPERTIES”

DISCOVERY

Carbon nanotube (CNTS) were first discovered in 1991 by the Japanese electron microscopist Sumio Iijima who was studying the material deposited on the cathode during the arc-evaporation synthesis of fullerenes.

CARBON NANOTUBE Carbon nanotubes (CNTs) are carbon allotropes Its nanoscopic in structure and in the shape of a

hollow cylinder cylinders closed both ends by semi-fullerene

structures. diameter as small as 1nm can have one “layer” or wall (single walled

nanotube) more than one wall (multi walled nanotube).

TYPES OF CARBON NANOTUBES

Armchair (n,m) = (5,5) = 30

Zig Zag (n,m) = (9,0) = 0

Helical (n,m) = (10,5) 0 < < 30

TYPES OF CARBON NANOTUBE

(AS PER WALL STRUCTURES)

Single walled Multi walled

METHODS OF SYNTHESIS OF CARBON NANOTUBES

ARC DISCHARGE METHOD Connect two graphite

rods to a power supply, place them millimeters apart, and throw switch. At 100 amps, carbon vaporizes in a hot plasma.

Can produce SWNT and MWNTs with few structural defects

Tubes tend to be short with random sizes and directions

CHEMICAL VAPOUR DEPOSITION

Place substrate in oven, heat to 600 C, and slowly add a carbon-bearing gas such as methane. As gas decomposes it frees up carbon atoms, which recombine in the form of CNTs

Easiest to scale to industrial production; long length

LASER ABLATION

Blast graphite with intense laser pulses; use the laser pulses rather than electricity to generate carbon gas from which the CNTs form; try various conditions until hit on one that produces prodigious amounts of SWNTs

CARBON NANOTUBE PROPERTIES Extremely high Young’s modulus 200x stronger than steel of the same

diameter The first synthetic material to have

greater strength than spider silk Excellent conductors of electricity

and heat

STRENGTHThe strength of the carbon-carbon bonds gives carbon nanotubes amazing mechanical properties. The Young's modulus of the best nanotubes can be as high as 1000 GPa which is approximately 5x higher than steel. The tensile strength, or breaking strain of nanotubes can be up to 63 GPa, around 50x higher than steel.

THERMAL CONDUCTIVITY CNTs very good thermal

conductors along the tube, exhibiting a property known as "ballistic conduction", but good insulators laterally to the tube axis. Measurements show that a SWNT has a room-temperature thermal conductivity along its axis of about 3500 W·m−1·K−1

 compare this to copper, a metal well known for its good thermal conductivity, which transmits 385 W·m−1·K−1.

ELECTRICAL PROPERTIES

Because of the symmetry and unique electronic structure of graphene, the structure of a nanotube strongly affects its electrical properties.  metallic nanotubes can carry an electric current density of 4 × 109 A/cm2, which is more than 1,000 times greater than those of metals such as copper.

PROPERTIES OF CARBON ALLOTROPES

++++++

+

no

+++++

no

Conducts

electricity

+ ++++ ++++

+ Buckybal

ls

+++++

+++++

++++++

Carbon Nanotub

es

+++ Not known

+++++

Diamond

+++++

++ ++ Graphit

e

+ + + Coal

Conducts heat

Tensile strength

Hardness

Allotrope

APPLICATIONS

Water filters

Bullet proof vest

THE SPACE ELEVATOR

OBSTACLES

Lack of vision to identify those aspects that could be changed through its use.

Lack of skilled personnel. Level of Investment.

CONCLUSIONTheir mechanical properties, and unique electronic properties make them both interesting & useful in future technologies, but growth

mechanisms yet to be fully established.

REFERENCES http://www.ipt.arc.nasa.gov http://www.mknano.com www.nanohub.org www.wikipedia.com Carbon nanotubes science and

applications BY M.Meyyapan

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