Composite for critical technology developed in India

Researchers at the Hyderabad-based Defence Research and Development Laboratory have developed a material which can withstand high temperatures and which has applications ranging from the aerospace industry to missile manufacturing. This is a significant development in the face of the embargo regime against India, DRDL sources said.

Designed and fabricated with the DRDL's indigenous technology, the 'CCC (carbon-carbon composite) material'' can withstand temperatures up to 3000 degrees centigrade.

It will be used to manufacture brake discs for the light combat aircraft and, later, for the Airbus A-320 and the nozzles of Indian-built missiles.

The DRDL technology has already been passed on to a Bangalore-based group for development and production of the brake discs. DRDL Carbon Composites Director G Rohini Devi told a symposium organised by the Hyderabad branch of the Aeronautical Society of India.

Presenting a technical paper on 'high temperature composites for aerospace applications' at the symposium she said the DRDL was working with the Technology Information, Forecasting and Assessment Council, the Director General of Civil Aviation and the Railway Development and Standards Organisation. It is also planning a deal with the Hindustan Aeronautics Limited to develop CCC brake discs for Vajra, the Mirage-2000 squadron of the Indian air force, the A-320 planes of Indian Airlines and possibility the MIG-BIS military aircraft.

The carbon composite can remain stable even at temperatures as high as 2500 degrees centigrade, and maintain it mechanical properties even at 3000 degrees. Handicapped by the non-availability of material and technology for high temperature materials following the embargo by developed countries, the DRDL group used the new braiding technique ''to weave carbon fibres'' together.

The resultant fibres were upgraded into a full-scale material. Now efforts are on to streamline the process.

Aircraft flying at speeds faster than sound need braking systems strong enough to handle the tremendous drag when an aircraft slows down; they also should be quickly absorb the high temperatures generated.

Conventionally, steel with sinter materials is used in brake discs but metal fatigue -- caused by both heat and friction -- and physical damage reduce their lifespan considerably.

The Japanese, she said, had already tried the ''new step'' process for using carbon composites for its racing cars. The CCC materials could also be used for high-speed rail engines, she said.

Rohini Devi said even the American tyre giants, Dunlop, had told the DRDL group that it could not develop the CCC used in the Concorde, the Airbus A-320 and the Mirage aircraft.

In fact, she said, the DRDL had developed two types of CCC materials for the LCA and the test under simulated conditions were tested for 2,000 landings under conditions close to reality.

She said the DRDL was preparing for an annual demand for about 200 CCC brake discs for the Vajra and about 2,000 CCC discs for the Airbus A-320.

Lab-scale evaluation of ceramic-based composites were under trail while there were plans for other possible composites, including Kevlar, used in shields of space vehicles. But the ceramic composites based on silicon now being considered, however, can withstand temperature only up to 1500 degrees centigrade. Efforts were on to improve its ability to handle high temperatures, she said, adding that other materials to be looked into were super-alloys.

The DRDL group, was also working on materials to use in rocket nozzles, which have to withstand high temperatures and vibration while looping back towards its target. The material, she said, could also be used in high temperature seals, throat inserts and swivels for civilian purpose. The DRDL technology, she said could be scaled up in a very big way for developing materials for rocket motors also.

Replying to questions from the audience, she said though the CCC could not be used straightway in cryogenic engines, which work at much lower temperatures, some silicon carbide composites which are not affected by low temperatures could be used in the cryo-engines being designed for the proposed geo-stationary space launch vehicles.

DRDL Director Lt Gen Dr V J Sundaram, said the laboratory was also trying to use the technique developed by the Hyderabad-based Nuclear Fuel Complex for air nozzles and to manufacture gallium arsenide, a material used in computer chips.