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 Vol. 9  No 5 October  2001            

Propellant Technology

Combustible Catridge Case Technology for Tank Gun Ammunition

Conventional brass cartridge case has certain limitations for use in modern tank gun ammunition. DRDO has developed indigenous combustible cartridge case (CCC) technology based on energetic materials, like nitrocellulose, cellulose, gas generator, stabiliser, plasticiser and additives to impart various desired properties of the CCC.

This technology is based on felting (moulding) process. During felting, fibres from the dilute slurry deposit on the felt. They are then dried and treated with solvent for gelatinisation, compacted at high pressure and thereafter dried to achieve high strength and trimmed to the  required dimensions.

Salient Features

  • State-of-the-art technology

  • Makes use of gas generating ingredient which improves burning characteristics and reduce muzzle flash

  • Safe as all operations are carried out at room temperature

  • Can produce CCCs in any shape and size

  • Based on indigenously available raw materials and equipment

Additive Liners

Additive linersHigh performance guns suffer fast erosion of gun barrel due to high temperature and high velocity of burning gases of the propellant. This erosion brings down the performance and accuracy and shortens the barrel life drastically leading to condemnation of costly gun barrel too early in its ballistic life. The erosion phenomenon has been ascribed to a combination of three factors, namely thermal, chemical, and mechanical.

DRDO has successfully solved the problem of barrel erosion by developing titanium dioxide-wax and talc-wax additive liners. The additive liners provide relief from the thermal factors by providing a cool boundary layer in barrel. This layer acts as a buffer between the hot combustion gases and the inner surface of the barrel. In addition, use of refractory metal oxides in the composition succeeds in providing a coating of fine powder on the inner surface of the barrel which reduces the turbulence of combustion of gases near the surface and prevents the passage of heat raDIATion .

The talc-wax additive liner has effectively increased the barrel life to more than 1000 rounds, whereas the Titanium dioxide-wax additive liner has increased the barrel life to around 500 rounds as against 250 rounds when no additive liner was used. These liners have been inducted into the Services and bulk production of both types of liners has commenced.