Application of Micro-CT and SEM Technology In-situ Observation of Damage Evolution of C/SiC Composites

In order to investigate the damage behavior of C/SiC composites, SEM and micro-CT were combined and run with in-situ tensile tests to study the damage phenomenology. The microscopic processes of crack initiation, propagation and failure of C/SiC composites with circular hole were directly observed under tensile load. The results show that the method proposed in this paper can be used to analyze and visualize crack initiation and propagation. The crack propagation of C/SiC composites is diverse when the material fails, and the morphology of the internal cracks observed in the micro- CT images is different from the surface cracks observed in the SEM images. The macroscopic holes of the C/SiC material and the boundary of the SiC matrix aggregate region often become the crack initiation of the specimen, and the main crack which eventually causes the failure of specimen is located in the preset macroscopic hole region. Through the method proposed in this paper, the micro-structure images of the specimen in the elastic deformation stage, micro-crack propagation stage and failure stage can be obtained, which correspond to the characteristics of the linear stage, curve stage and fluctuation stage of the load-displacement curve respectively. The microscopic observation method combined with micro-CT and SEM is important and useful to the study of the failure evolution mechanism of C/SiC composite materials.