Response to internal pressure shock and hoop strength of SiCf/SiC cladding

Abstract

This study investigated the mechanical behavior of silicon carbide fiber-reinforced silicon carbide matrix (SiCf/SiC) cladding using expanding plug tests at 0.5 and 2 mm/min. A three-stage mechanical response for SiCf/SiC was observed, with significant differences in Stage 3 between specimens tested at different rates. Specimens tested at the slower rate (0.5 mm/min) exhibited a characteristic hoop strength of 112.4 MPa and homogeneous destruction behavior, indicative of uniform stress distribution. In contrast, the hoop stress in SiCf/SiC became unsteady at the faster rate (2 mm/min), leading to cracking at a lower nominal proportional limit stress (PLS), structural instability, non-uniform fiber pull-out, and a lower characteristic hoop strength of 92.4 MPa. This suggests that similar phenomena might occur at higher loading rates during internal pressure shock. Therefore, considering the application of SiCf/SiC, to conduct hoop strength testing at faster rates was recommend, such as 2 mm/min.