Microstructural characterization and tensile behaviour of a 3D braided C/SiC composite fabricated by chemical vapour infiltration

The microstructure of a 3D C/SiC composite was characterized and the tensile behaviour was investigated in conjunction with acoustic emission (AE) technique. A computer model of the fibre architecture was generated for visualization and further stress analysis. The results show that the stress-strain curves exhibit mostly nonlinear behaviour with four distinguishable regions, which compare well with the AE characteristics. Microstructural observations reveal the superficial matrix cavities and large inter-bundle pores due to the 3D braiding fibre architecture. The failed specimens show ragged fracture surfaces and extensive fibre pullout, as well as interfacial debonding.