CARBON NANOTUBES

By ANIKET KANSE60011115022

What are Carbon nanotubes?• Carbon nanotubes (CNTs) are allotropes of carbon.

TYPES OF CARBON NANOTUBES

• Single walled carbon nanotubes

• Multi-walled carbon nanotubes

• Nanobuds

SINGLE WALLED CARBON NANOTUBES

ARRANGEMENTS

MULTI-WALLED CARBON NANOTUBES

• MWNT consist of multiple layers of graphite rolled in On themselves to form a tube shape.

CARBON NANOBUDS

• It is discovered material combining two previously discovered allotropes of carbon: carbon nano tubes and fullerenes. In this new material fullerene-like "buds" are covalently bonded to the outer sidewalls of the underlying carbon nano tube.

PROPERTIES

• Strength• Electrical• Thermal • Defects• Toxicity

STRENGTH

• Carbon nanotubes have the strongest tensile strength of any material known.

• It also has the highest modulus of elasticity.

Material Young's Modulus (TPa)

Tensile Strength (GPa)

Elongation at Break (%)

SWNT ~1 (from 1 to 5) 13-53E 16Armchair SWNT 0.94T 126.2T 23.1

Zigzag SWNT 0.94T 94.5T 15.6-17.5Chiral SWNT 0.92MWNT 0.8-0.9E 150Stainless Steel ~0.2 ~0.65-1 15-50

Kevlar ~0.15 ~3.5 ~2

KevlarT 0.25 29.6

ELECTRICAL PROPERTIES

• Armchair’s electrical property is metallic.

• Chiral’s electrical property can be either semiconducting.

• In theory, metallic nanotubes can carry an electrical current density of 4×109 A/cm2 which is more than 1,000 times greater than metals such as copper

THERMAL PROPERTIES• All nanotubes are expected to be very good thermal

conductors along the tube, but good insulators laterally to the tube axis.

• It is predicted that carbon nanotubes will be able to transmit up to 6000 watts per meter per Kelvin at room temperature.

• The temperature stability of carbon nanotubes is estimated to be up to 2800oC in vacuum and about 750oC in air.

PRODUCTION OF CARBON NANOTUBES

The methods are :-•THE CARBON ARC METHOD•LASER METHOD•CHEMICAL VAPOR DEPOSITION•BALL MILLING

CARBON ARC METHOD

LASER METHOD

• It is synthesized using a dual-pulsed laser and achieved yields of >70% purity. Samples were prepared by laser vaporization of graphite rods with a 50:50 catalyst mixture of Cobalt and Nickel at 1200°C in flowing argon, followed by heat treatment in a vacuum at 1000°C to remove the C60 and other fullerenes.

CHEMICAL VAPOR DEPOSITION

• Hydrocarbon + Fe/Co/Ni catalyst 550-750° CNT

• Methane + Porous Si + Fe pattern CVD

Aligned MWNTs

PURIFICATION OF CNT’S

• Oxidation

• Acid treatment

• Annealing

• Magnetic purification

DEFECTS

• Defects can occur in the form of atomic vacancies.

• Because of the very small structure of CNTs, the tensile strength of the tube is dependent on its weakest segment in a similar manner to a chain, where the strength of the weakest link becomes the maximum strength of the chain.

APPLICATIONS

• Nanotubes hold the promise of creating novel devices, such as carbon-based single-electron transistors, that significantly smaller than conventional transistors.

Nanotubes’ excellent strength to weight ratio creates the potential to build an elevator to space.

SUPER STRONG BULLET PROOF JACKETS:-

QUANTUM COMPUTING

• Nanotubes and other Fullerenes can be filled with molecules that have either an electronic or structural property which can be used to represent the quantum bit (Qubit) of information, and which can be associated with other adjacent Qubits.

HEALTH HAZARDS

• According to scientists at the National Institute of Standards and Technology, carbon nanotubes shorter than about 200 nanometers readily enter into human lung cells similar to the way asbestos does, and may pose an increased risk to health.

• Carbon nanotubes along with the majority of nanotechnology, are an unexplored matter, and many of the possible health hazards are still unknown.