Evaluation on fracture resistance of advanced SiC/SiC composites using single- and double-notched specimens

Nozawa, Takashi; Kato, Yutai*; Kishimoto, Hirotatsu*; Koyama, Akira*

One of the advantages for highly-crystalline and stoichiometric silicon carbide (SiC) composites (advanced SiC/SiC) is improved stability of chemical, physical and mechanical properties at high-temperatures. Besides, it has been revealed that significant contribution from the optimized fiber/matrix (F/M) interface enables to give good quasi-ductility beyond matrix cracking. Though the importance of the F/M interfacial role is recognized, understanding the mechanism of crack propagation is insufficient. Meanwhile, the existing test methods to determine fracture resistance of composites, i.e., a critical energy required to propagate a crack, are not fully established because of very limited considerations on the influence of irreversible energies emerged by interaction at the F/M interface and microcrack forming. This study aims to develop a fracture resistance test methodology and to quantify the crack resistance of advanced SiC/SiC composites.