The degradation behavior of UHTCs based coatings coated PIP-C/SiC composites in thermal cycling environment

UHTCs based coatings (ZrB2–SiC coating and ZrC–SiC coating) are prepared on the surface of PIP-C/SiC composites by slurry and CVD method, and the thermal stability is one of the key issues for C/SiC composites. This study aims to study thermal shock behavior of the coated composites. The results show the degradation of flexural strength without obvious variation, and the fracture mode and pull-out mechanism are also changed. The composition of coatings is characterized by XRD, SEM and XPS. The decrease of flexural strength during the tests is due to the debonding of the coating-matrix interfaces. Compared to uncoated C/SiC composites, the UHTCs based coatings are able to improve the mechanical properties of the composites.