5.0 New High Performance Materials

Carbon fibres are a new breed of high performance materials. Which have attracted world wide attention and hold great promise for the future? This is because of the fact that these fibres are stronger than steel, stiffer than titanium and lighter than aluminium. These qualities have placed carbon fibres on top of the list of many moved materials available today. Carbon fibres are produced in number of ways and form a variety of starting materials or precurors such as viscose rayon, polyacrylonitrile, pitch, resins, gases such as (methane, and benzene). Their characteristics are strongly influenced by the manufacturing techniques employed.

Carbon fibres reinforced in a right weight matrix, generally on expoxy resin, polyester resin or polyamide are called carbon fibre reinforced plastics (CFRP). When the carbon fibre are reinforced in a carbon matrix, they are known as carbon fibre reinforced carbon (CFRC), commonly known as carbon – carbon composites.

On the basis of their reinforced of carbon fibres carbon fibre reinforced plastics (CFRP) and carbon fibre reinforced carbons (CFRC). Their applications can be broadly classified in to three categories:

1. High technology sector including aerospace, military and nuclear fields.

2. General engineering sector including sports transportation and chemical fields.

3. Biomedical sector: In the aerospace sector, the composites are used for air craft using, tail parts, helicopter rolor blades and using spoilers. The floor decking of air ships is also made from carbon fibre-reinforced composites. Interest in applications involving helicopters continues and it is believed that the first all composite aircraft to fly will be helicopter. Helicopter rolor blades made form CFRP not only give better performance but are less expensive than the metal blades.

Carbon fibre in the form of carbon fibre reinforced carbon commonly known as carbon composites brakes perform three to five times better than their steel counter parts.

The high thermal conductivity of carbon fibres enhances the heat dissipation in components such as well materials of nuclear fission reactor, gears brakes pads, bearing, fan blades, automobile parts and other friction related products. Further the low coefficient of thermal expansion makes it possible to design structures with zero or very low planar thermal expansion.

Carbon fibres in the form of CFRP find mainly used in the area of sports goods. Very superior specific strength and stiffness, coupled with good fatigue, resistance, make them versatile materials for fishing rods, sky poles, tennis and badminton rockets, racing cycle frames and racing car bodies.

In the biomedical field, carbon fibres have exciting applications, such as components of bone plates hip joint prostheses, ligaments and hydraulic motors for artificial heart implants. Activated carbon fibres are finding increasing applications in appliances for water treatment, gas masks, air filters, catalyst carriers for platinum and so on. Activated carbon fibres in textile form are used in extremely hostile environments. The main advantages of using carbon fibres are that they can be woven in any form and a surface area of as high as 3000m2/g can be obtainssed.

Carbon fibres in India are mainly used in defence sector as nose tips and head shields of missiles (like ‘agni’) by DRDO, Hyderabad, and in the aerospace sector by ISRO and other aerospace organization for producing components parts, nozzles of rocket/missiles