Failure behavior investigation of a unidirectional carbon-carbon composite

The failure behavior and morphology of a carbon-carbon composite (C-C composite) manufactured by isothermal chemical vapor infiltration was studied by three-point bending tests, polarized light microscope and scanning electron microscope, respectively. The C-C composite was reinforced by PAN-based carbon fiber aligned in only one direction. Flexural strength and modulus of the composite were 200.9. MPa and 50.5. GPa, respectively. Failure behavior of the unidirectional C-C composite can be described as three stages including brittle fracture behavior at beginning, quasi-ductile behavior finally, and fluctuation behavior between them. Two main kinds of cracks, namely cracks parallel and perpendicular to loading direction alternately resulted in deformation evolution of the composite. The strength of interfacial bonding and cracks orientation played key roles to failure behavior of C-C composite.