Carbon+Fibre

Carbon Fiber By Kalen Leung Many of you have probably heard of the term "Carbon Fiber" before, but you wonder.... how is it made? What can humans use it for? What is it really? That is what I am going explain.

Carbon Fibre is also known as graphite fibre or carbon graphite. Carbon fibres are strands of long chains of carbon called carbon nanotubes. The diameter of these strands is approximately 0.005 – 0.010 mm. Carbon fibre is very strong and be made to strands that can have a length to diameter ratio of 132,000,000:1, which is significantly larger than any other material. Carbon fibre is ridiculously strong, but at the same time extremely expensive.

Carbon fibre is extremely strong due to the interlocking and circular shape of their chemical formula. The bonding of a nanotube is described by quantum chemistry. Nanotubes have mainly sp2 bonds which are naturally stronger than the chemical bonding of diamonds, sp3. So yes. Carbon fibre is harder than diamonds. A decade ago, a multi walled carbon fibre nanotube was tested for tensile strength. It held 6422Kg on just 1mm ² . The Carbon Nanotubes naturally align themselves into ropes held together by van der Waals forces. With immense strength, weaknesses come. Although they are very strong, the carbon nanotubes are unfortunately hollow. The nanotubes will undergo buckling, a complete failure of the structure, when enough force is applied.

Nanotubes are categorized as single-walled nanotubes (SWNT) or multi-walled nanotubes (MWNT). Carbon nanotubes (1/50,000th the width of human hair)(CNT) which makes up carbon fibres are the strongest and stiffest materials yet discovered in tensile strength and elastic modulus.

So many are wondering if carbon fibre is so strong “why don’t humans use it?” Well the thing is it is very new to humans. Carbon fibres are in fact unbelievably expensive. The basic equipment needed to produce the carbon fibres starts at 25$ million.

The complex production of carbon fibres is very time comsuming. There are many steps to producing carbon fibres and each company makes it differently than their competitors. The first step, polymerization, is done with polyacrylonitrile(PAN). PAN is the base for carbon fibers. PAN is mixed with a catalyst. The stirring helps polymerization, which is the chemical process for creating long-chain polymers that can be formed into acrylic fibres. After washing and drying the acrylic fibres, they are crushed to form a powder. The powder is mixed with a solvent and produce a mixture with the consistency of maple syrup. The variations in different companys is in the kind of solvent used. The mixture is now known as PAN fibres. The PAN fibres are formed with spinning. The spinning seperates the mixture into tiny holes. Te fibres are coated with oil to prevent cluping and is now wound onto bobbins. The PAN fibre bobbins are now put into oxidaion. The oxiation oven combines oxygenin the ai with the pan fibres and causes the intricate crosslinking of the polymer chains. This crosslinking produces the strength from the carbon fibres. The carbon is then moved to the next step, but some go back into series of oven and different times, depending on companys. The PAN fibres now contains approximately 50-60% carbon molecules with a mixture of hydrogen,nitrogen,and oxygen. The natural gases in air. Cabonization then takes place. In the carbonization ovens, the temperature is extemely high so all the oxygen is burned up.The temperatures start at 750 degrees and finish at 1500 degree centigrade. When PAN fibres enter the carbonization chambers, most of the gases are burned up, and the final product contains more than 90% carbon. Depending on the temperature. (At 2500 degrees centigrade 99% are carbon atoms.) Carbonization only takes minutsand it greatly reduces it's size and weight. The final step is crutial to the quality of carbon fibres. Surface treatment and sizings. The carbon fibres are put into electrochemical baths because it helps with adhesion and increases surface area available for fiber bondigs. The final step is to put a sizing on. This accounts for approximately 5% of the carbon fibre's weight. This protects it from handling and processing. When it dries, the long process of carbon fibre production is over.

Carbon fibres have been used in many different ways. One way that carbon nanotubes are reaching humans is very unique. It is being used as artificial muscles. Carbon nanotubes are as light as air, stronger than steel, but as bendy as rubber. A bundle of this will twitch, when a voltage is applied. The artificial muscles can expand about 4000 times faster than a natural muscle can.

Many have probably heard of carbon fibre – reinforced polymers. What does that mean? It means that carbon fibres have been mixed with certain polymers to give extra strength much like fibreglass. Many people have used carbon fibre –reinforced polymers to help with aerospace projects, and in automotive fields. The high strength to weigh ratio is very important for this use. Carbon fibre is a revolutionary discovery. Because of its immense strength, more superior to diamonds, and the commercial production, many items in the future will use this powerful strength to weight ratio to their advantage; little do they know this is just another one of those carbon chains.



[]

[]

[]

[]

[]

[]

After looking at other people's pages. I have a bad page. T.T Sorry Ms. Kim.