ABSTRACT: Carbon nano tubes are allotropes of carbon. Carbon nano tubes are just a few billionths of a meter across, but are ultra strong. Their unusual properties promise to revolutionize electronics, computers, chemistry and material sciences. They had been discovered in 1991. One of the main applications of carbon nano tubes is super strong bullet proof vests. A new bullet proof material is designed which actually rebounds the force of a bullet. Bulletproof materials at the moment are designed to spread the force.The nature of the bonding of a nano tube is described by applied quantum chemistry, specifically, orbital hybridization. The chemical bonding of nano tubes are composed entirely of sp2 bonds, similar to those of graphite.The lightweight fiber, made up of millions of
tiny carbon nano tubes, is starting to reveal exciting properties. The fiber is very strong, lightweight and good at absorbing energy in the form of fragments traveling at very high velocity. Inherent property of elasticity is the main reason for it. Carbon nano tubes exhibit extraordinary mechanical properties. It is as stiff as diamond. The material is already up to several times stronger, tougher and stiffer than fibers currently used to make protective amour. For body armour, the strength of the fibers in a fabric is critical parameter. Recently preparing bullet proof t-shirts can save lots of people from bullet hits. In future, these amours can be used for military applications.
INTRODUCTION: Technology that works at the nanometer scale of molecules and atoms will be a large part of nano technology. This technology will be enabling great improvements in all the fields of human presence .Electronics is an area where nano technology making great gain. CARBON NANOTUBES is one of the main applications of nano technology. Carbon nano tubes are allotropes of carbon. They are of so many types. Among them single nano tubes have more significance. A carbon nano tube
is a one-atom thick sheet of graphite rolled up into a seamless cylinder with diameter on the order of a nanometer. This results in a nanostructure where the length-to-diameter ratio exceeds 1,000,000. They exhibit extraordinary strength and unique electrical properties. The inherent property of elasticity made them to show rebounding property. The nano tubes are created rapidly by squirting a carbon source, like ethanol, and an iron nano catalyst through a hydrogen carrier, and into a furnace at 1,200 degrees Celsius.
The size of the nano tube is in the order of few nano meters, approximately 1/50000th of the width of a human hair, while they can be up to several millimeters in length. . Nano tubes are mainly categorized as single-walled nano tubes and multi-walled nano tubes. Among them single walled tubes are used to make bullet proof vests which are mainly used for military applications.
hybridization. The chemical bonding of nano tubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, which is stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nano tubes naturally align themselves into "ropes" held together by Vander Waals forces. The bonding in carbon nano tubes is sp², with each atom joined to three neighbours, as in graphite.
EVOLUTION: They had been discovered in 1991.The current huge interest in carbon nano tubes is a direct consequence of the synthesis of buckminsterfullerene, C60. The search was given new importance when it was shown in 1990 that C60 could be produced in a simple arc-evaporation apparatus readily available in all laboratories. The tubes contained at least two layers, often many more, and ranged in outer diameter from about 3 nm to 30 nm. They were invariably closed at both ends. In 1993, a new class of carbon nano tube was discovered, with just a single layer. It was soon established that these new fibers had a range of exceptional properties (see below), and this sparked off an explosion of research into carbon nano tubes Recent research has focused on improving the quality of catalytically-produced nano tubes.
STRUCTURE: The nature of the bonding of a nano tube is described by applied quantum chemistry, specifically, orbital
The tubes can therefore be considered as rolled-up graphene sheets. The first two of these, known as “armchair” (top left) and “zigzag” (middle left) have a high degree of symmetry. The terms "armchair" and "zigzag" refer to the arrangement of hexagons around the circumference. The third class of tube, which in practice is the most common, is known as chiral, meaning that it can exist in two mirror-related forms. An example of a chiral nanotube is shown at the bottom left. Condensing on the walls of the reaction vessel and some of it on the cathode. It is the deposit on the cathode which contains the carbon nano tubes. Single-walled nano tubes are produced
when Co and Ni or some other metal is added to the anode. It has been known since the 1950s, if not earlier, that carbon nano tubes can also be made by passing a carbon-containing gas, such as a hydrocarbon, over a catalyst. The catalyst consists of nano-sized particles of metal, usually Fe, Co or Ni. These particles catalyze the breakdown of the gaseous molecules into carbon, and a tube then begins to grow with a metal particle at the tip. It was shown in 1996 that single-walled nano tubes can also be produced catalytically. The perfection of carbon nano tubes produced in this way has generally been poorer than those made by arcevaporation, but great improvements in the technique have been made in recent years. The big advantage of catalytic synthesis over arc-evaporation is that it can be scaled up for volume production. The third important method for making carbon nano tubes involves using a powerful laser to vaporize a metal-graphite target. This can be used to produce single-walled tubes with high yield.
FIG: MODELS OF NANO TUBES narrower than the multi walled tubes, with diameters typically in the range 12 nm, and tend to be curved rather than straight. The image on the right shows some typical single-walled tubes Single-walled nano tubes are a very important variety of carbon nano tube because they exhibit important electric properties that are not shared by the multi-walled carbon nano tube variants. These tubes are used to make super strong amour bodies. They have elastic property and hence used to make bullet proof vests. 2. MULTI WALLED:
Carbon nano tubes of different types. They are:
Multi-walled nano tubes consist of multiple layers of graphite rolled in on themselves to form a tube shape. There are two models which can be used to describe the structures of multi-walled nano tubes. The special place of double-walled carbon nano tubes must be emphasized here because they combine very similar morphology and properties as compared to SWNT, while improving significantly their resistance to chemicals. This is especially important when fictionalization is required to add new properties to the CNT
1. SINGLE WALLED
3.FULLERITE:
Single-walled nano tubes are generally
Fullerites are the solid-state manifestation of fullerenes and related compounds and materials. Being highly incompressible nano tube forms, polymerized single-walled nano tubes are a class of fullerites and are comparable to diamond in terms of hardness. However, due to the way that nanotubes intertwine, they don't have the corresponding crystal lattice that makes it possible to cut diamonds neatly. This same structure results in a
Types of carbon nano tubes:
less brittle material, as any impact that the structure sustains is spread out throughout the material.
4. NANO BUD:
A stable nano bud structure Carbon nano buds are a newly 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. This hybrid material has useful properties of both fullerenes and carbon nano tubes. In particular, they have been found to be exceptionally good field emitters. Among all types, bullet proof vests can be made from single walled nano tubes.
SPECIFIC APPLICATION-SUPER STRONG BULLET PROOF VESTS: One of the main applications of carbon nano tubes is super strong bullet proof vests. Bullet proof vests are woven by the carbon nano fibers which are made up of millions of tiny carbon nano tubes is starting to reveal exciting properties. A new bullet proof material is designed which actually rebounds the force of a bullet. Bulletproof materials at the moment are designed to spread the force. The lightweight fiber, made up of millions of tiny carbon nano tubes, is starting to reveal exciting properties the lightweight fiber. The fiber is very strong, lightweight and good at absorbing energy in the form of fragments travelling at very high velocity. So it can be used as body amour. Carbon nano tubes have great potential applications in making ballisticresistance materials. The remarkable properties of carbon nano tubes makes them an ideal candidate for reinforcing polymers and other materials, and could lead to applications such as bullet-proof vests as light as a T-shirt, shields, and explosion-proof blankets. For these applications, thinner, lighter, and flexible materials with superior
Conduct electricity as copper. These fibers can be used as space elevators. dynamic mechanical properties are required. It should explore the energy absorption capacity of a single-walled carbon nano tube under a ballistic impact. The result offers a useful guideline for using carbon nano tube as a reinforcing phase of materials to make devices to prevent from ballistic penetration or high speed impact. . It is as stiff as diamond
HOW DOES BULLET PROOF VEST WORK?
Bulletproof jackets do not turn security guards, police officers and armed forces into Robocops, repelling the force of bullets in their stride. New research in carbon nanotechnology however could give those in the line of fire materials which can bounce bullets without a trace of damage.
PRINCIPLE : The main principle is Carbon nano fibers are good at absorbing energy so they can absorb the energy coming from the bullet. The inherent property of elasticity makes the bullet to rebound.
STRENGTH OF FIBRE: It is 100% stronger than the steel. Lighter than aluminum
A research paper published in the Institute of Physics' Nanotechnology details how engineers from the Centre for Advanced Materials Technology at the University of Sydney have found a way to use the elasticity of carbon nanotubes to not only stop bullets penetrating material but actually rebound their force.
amount of energy. The fivers are usually twisted individually and the material covered by a double coat of resin and plastic. The second most used material is Vectran, which is two times stronger than Kevlar. New trends include spider web, feathers and carbon nano tubes.
HOW DOES THE BULLET PROOF VEST STOP BULLETS? When the bullet strikes the jacket, the fiber shows its elastic property and rebounds the bullet. The Engineers in Australia have designed a new bullet proof material which actually rebounds the force of a bullet. Bulletproof materials at the moment are designed to spread the force. The use of nanotechnology in design means those in the line of fire can be shot without a flinch. Also known as body amours, there are different types of bullet proof vests. The most common is the soft vest usually used by the police force and private security; it cannot stop ammunition of big caliber. Hard-plate reinforced vests are necessary when heavy ammunition is involved; they are used as part of the default equipment in the Army. Soft bullet proof vests are formed from advanced woven fibers that can be sewn into vests and other soft clothing. The fibers form a tight interlaced net which disperses the energy of the bullet reducing its speed until it stops. The most effective material used in body armor is Kevlar fiber. Kevlar is light as cloth, but five times stronger than a piece of steel of the same weight. When interlaced into a dense net, this material can absorb a great
The bullets do so much damage because of the focused blunt trauma: they focus all the impact in a reduced area increasing the penetration rate. Bullet proof vests are designed to spread the energy laterally over the whole vest while deforming the bullet at the same time. The system works as the net of a soccer goal, lateral tension of the net spreads the energy of the impact and stops the ball without reflecting it (in most cases), the collision is completely inelastic. When hard protective pieces are added, the bullets might be deflected instead of stopped, but in the case of soft body armor it is extremely difficult to deflect a bullet, it will be trapped by the material and stopped. Most anti-ballistic materials, like bullet-proof jackets and explosionproof blankets, are currently made of multiple layers of Kevlar, Twaron or Dyneema fibers which stop bullets from penetrating by spreading the bullet's force. The elasticity of carbon nano tubes means that blunt force trauma may be avoided and that's why the engineers in Sydney have undertaken experiments to find the optimum point of elasticity for the most effective bullet-bouncing gear.
Scientists have used the elasticity of carbon nano tubes to not only stop bullets penetrating material but to actually rebound their force. Clothing woven from the fibers that could store electrical energy, much like a battery, and be used to power various electrical devices. Synthetic muscles capable of generating 100 times the force of the same diameter natural muscle. Distributed fiber sensors able to monitor the movement and health of “first responders” to emergencies. A power source for spacecraft on long voyages through conversion of thermal energy to electrical energy using nanotube fibers.
SCOPE FOR FUTURE WORK: "Although we might be making several kilometers a day, it's a very thin fiber, weighing much less than a gram, "We have to scale this up to make kilograms. Before anyone will commit the huge investment needed to build a full-scale plant, they need to know that it will make a good bullet-proof vest." The research is going on to prepare protective body suits. Body amour for women personal. Reinforced soft and hard body armour. Helmet and body protective device. Breathable garment to be woven to improve the comfort of the human body.
CONCLUSION: We conclude that these bullet proof vests are very effective and essential for the coming generations. As these are made from carbon nano fibers, which are readily available and less in cost, the coming generations will be benefited more. These are safe and protective than the bullet proofs which are used in these days. A new generation of bullet-proof vests and anti-ballistic materials that are much more effective than those in use today.
