The effects of inherent solid particulates on the structure and mechanicalproperties of coal-tar pitch based C-C composites

Five unidirectional C-C composites were prepared using PAN-based carbon fib res and five pitches differing only in their inherent solid particles (QI) content. The results show that QI content affects the microstructure of the composite matrices The amount of smaller size crystalline structures (mosa ic-like) increases with the increase of pitch QI content. On the other hand , QI particles also produce a significant increase in carbon yield, and con sequently, composites show a higher percentage of carbon matrix. Mechanical properties, especially compressive strength, are also affected by the pres ence of QI particles. With the increase in QI content the mechanical proper ties of the composites are improved. However, this improvement always bring s about a more brittle behaviour in the material, which is mainly due to th e increase in the strength of fibre-matrix bonding. A good correlation betw een compressive and apparent interlaminar shear strength was found.