Microstructure plays an important role in controlling the fracture behaviour of carbon-carbon composites and hence their mechanical properties. In the present study effort was made to understand how the different interfaces (fiber/matrix interactions) influence the development of microstructure of the matrix as well as that of carbon fibers as the heat treatment temperature of the carbon-carbon composites is raised. Three different grades of PAN based carbon fibres were selected to offer different surface characteristics. It is observed that in case of high-strength carbon fiber based carbon-carbon composites, not only the matrix microstructure is different but the texture of carbon fiber changes from isotropic to anisotropic after HTT to 2600℃. However, in case of intermediate and high modulus carbon fiber based carbon-carbon composites, the carbon fiber texture remains nearly isotropic at 2600℃ because of relatively weak fiber-matrix interactions.

• S.R. Dhakate(Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory)
• R.B. Mathur(Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory)
• T.L. Dhami(Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory)
• S.K. Chauhan(Carbon Technology Unit, Engineering Materials Division, National Physical Laboratory)