Control of fracture behavior of carbon fiber/pitch-based carbon matrix composites with microspace modification concept

Theoretical consideration was conducted on a relation between pore diameter and interfacial area between pores and fibers when pores uniformly distribute in C/C composites. It was shown that bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter, and consequently a new idea of microspace modification concept was proposed for controlling fracture behavior of C/C composites. Four types of C/C composites with various pore structures were fabricated by hot-pressing, and their fracture behavior was investigated by three point bending tests. The fracture behavior of the C/C composites was changed from brittle one to pseudo ductile one with decreasing the pore diameter. This result supported the validity of the microspace modification concept proposed in this paper.