Carbon fibre is a lightweight yet
strong substance. Many things from sports equipment like golf clubs and tennis
racquets to sports cars use carbon fibre. Carbon fibre is easily identifiable
by its unique chequered appearance.
What is carbon
fibre?
Carbon fibre is a material that is
made from very thin fibres having carbon atoms. These are bonded together in
microscopic crystals, aligned parallel to the long axis of the fibre. It is
this crystal alignment that makes carbon fibre so strong. Carbon fibre is
used to make composite materials with plastics resins. Carbon fibre has
the strength of steel, yet is lightweight. It also does not expand when heated
due to its high heat resistance. When stretched or bent, carbon fibre is very
strong, but if you subject it to high shock or compression, such as hitting it
with a hammer it will break. Carbon fibre has the best weight to strength
ratio.
The first carbon
fibres
You might be surprised to know that
carbon fibre is by no means a recent discovery. Thomas Edison used carbon fibre
filaments in his early light bulb experiments back in 1879. He created these
fibres by heating bamboo in a controlled environment. The carbon fibre
Edison carbon made was from cellulose-based materials, today it is made from
petroleum bases. The carbon fibres that Edison made out of the bamboo fires were
fire resistant, making it ideal for his filament for incandescence.
The carbon fibres
that Edison made out of the bamboo fires were fire resistant, making it ideal
for his filament for incandescence.
Later in 1958 Roger Bacon would try
to make carbon fibres from strands of rayon but these fibres were not very
strong. It was only later in 1963 that the Royal Aircraft Establishment at
Famborough, Hampshire UK developed strong carbon fibre. Rolls Royce used this
in their aeroplane engines.
Today carbon fibre is made from the
polymer PAN. Once this polymer is produced it is stretched in a manner 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 embedding in an epoxy resin. What you get in
the end is the characteristic black carbon fibre sheet which you can use to
make a variety of things.
Types of carbon
fibre compounds and their uses
Carbon fibre compounds are very
expensive compounds. Different types of carbon fibre compounds can be used for
a variety of purposes. For high temperature applications, carbon fibre
reinforced graphite is ideal. Carbon fibre can be used to filter high temperature
gases as a corrosion resisting electrode with an anti-static component.
Carbon fibre compounds with metals are avoided as the combination forms metal
carbides. The metals in these compounds eventually corrode. Today carbon fibre
is even having applications in the field of medicine. Carbon fibres are used to
complement regular skin for skin grafts.
No comments:
Post a Comment