Abstract

Five unidirectional C–C composites were prepared using PAN-based carbon fibres 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 (mosaic-like) increases with the increase of pitch QI content. On the other hand, QI particles also produce a significant increase in carbon yield, and consequently, composites show a higher percentage of carbon matrix. Mechanical properties, especially compressive strength, are also affected by the presence of QI particles. With the increase in QI content the mechanical properties of the composites are improved. However, this improvement always brings about a more brittle behaviour in the material, which is mainly due to the increase in the strength of fibre–matrix bonding. A good correlation between compressive and apparent interlaminar shear strength was found.