The Science Behind Carbon Fibre

Carbon fibre is a new material that is becoming ever more popular; especially in sport like cycling, skiing and motorsport. As the material becomes cheaper it is being used in road cars like the Alfa Romeo 4C and BMW M3. The reason for its expanding usage is because carbon fibre is over 66% lighter than steel yet 5 times stronger, making it a very desirable material. The materials flexibility can also be changed according to the function that is required.

Carbon fibre is a material made of very thin fibres of carbon atoms that are bonded together with microscopic crystals. In 1958 Roger Bacon tried to make carbon fibre strands, but they were not strong enough. In 1963, the Royal Aircraft Establishment at Farnborough, Hampshire developed strong carbon fibre; Rolls Royce uses this in their aeroplane engines.

Carbon Fibre is made by Producing Polymer Polyacrylonitrile this is then stretched so that it becomes parallel to the axis of the fibre. This polymer is then oxidised at a temperature of 200°C to 300°C to remove hydrogen and add oxygen to the molecule. The polymer is further purified by carbonisation, done by heating it to a temperature of 2500°C in a nitrogen rich environment.  The result depends on the quality of the fibre and is a polymer having more than 90% carbon in it. The final step in the manufacture of carbon fibre is called sizing. Here the fibres are weaved into sheets and are embedded in an epoxy resin. This process creates a sheet of flexible carbon fibre that can be moulded into almost any shape. Moulding is done by placing the carbon fibre fabric into a mould with release agent like paste wax and polyvinyl alcohol to stop the carbon fibre sticking to the mould. Adhesive is applied to the fabric to make it stay in place, carbon fibre fabric is then layered, thickness depending on the strength needed. A plastic film is put over the layered fabrics to stop the carbon fibre sticking, and then breathing fabric is put on top to spread the pressure evenly and prevent air pockets. Once the fabric is prepared, a bag is put over the part; this is sealed so the bag is airtight. The bag is then vacuumed pressuring the layers of fabric together creating carbon fibre; the product can then be removed from the mould. Carbon fibre gives the properties many materials can’t replicate; its very light, very strong and can be moulded into almost any shape needed. On the other hand, not many materials take up so much time and cost to manufacture.

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