Impact of grinding process on the mechanical behavior of CVI-SiC/SiC tubes for nuclear application

SiC/SiC composites are promising candidates for nuclear fuel cladding due to their outstanding mechanical resistance and properties at high temperatures (>1200°C). During the manufacturing process, a grinding phase of both the external and internal surfaces is required to respect the dimensional specifications which results in local modifications. In this work, the impact of the grinding process on the mechanical behavior is studied. For that purpose, several batches have been produced with various surface finishes, differing in their level of internal and external grindings (raw CVI tubes, tubes ground at the inner and outer sides with a fine control of grinded thickness). On the one hand, the mechanical behavior was investigated by performing uniaxial cyclic tensile tests and monitoring several inherent parameters. On the other hand, the microstructure was studied in the initial and final states by cross-sectional microscope observations and scanning electron microscopy performed on fracture surfaces. To establish microstructure/properties relationships, a unidirectional model is used. It has been enriched to take into account the investigated CVI-SiC/SiC tubes specificities. Today, the implemented model allows understanding the impact of local defects induced by the different levels of grinding on the tubes mechanical behavior.