Compressive properties and failure mechanism of 3D C/C composites

By means of scanning electronic microscope (SEM), laser scanning confocal microscope (LSCM) and mechanical properties measuring, the microstructure morphology and the compressive mechanical properties of the 3D C/C composite along x, y and z directions were studied. The results show that there are obvious defects, and there is weak adhesion in the fiber/matrix interface of the 3D C/C composite. The compressive strength and fracture strain along z direction are all much greater than those along x direction and y direction. The compressive fracture mechanism of 3D C/C composite was also investigated based on the macro-pictures of the fracture surface of specimens. The results show that the compressive stress-strain curves exhibit the almost linear characteristics at the beginning, and show nonlinear characteristics with the time. Failure models of the samples under compressive load along x, y and z directions present shear fracture. The fiber/matrix interfacial strength has a great effect on the compressive failure mechanism.