Fracture toughness and progressive damage mechanisms of 2.5D woven SiCf/SiC composites

This paper presents the effects of matrix and interface on the fracture toughness and progressive damage mechanisms of 2.5D woven SiCf/SiC composites. Third-generation SiC fibers were selected. 2.5D woven SiCf/SiC composites with four interfacial layers PyC, PyC/SiC, BN, BN/SiC and two matrix polycarbosilane (PCS) and liquid hyperbranched polycarbosilane with vinyl groups (VHPCS) were prepared by a combination of chemical vapour deposition (CVD), chemical vapor infiltration (CVI), and precursor infiltration pyrolysis (PIP) processes, respectively. Single edge notch bending (SENB) tests were carried out to investigate the fracture toughness. Moreover, acoustic emission (AE) and X-ray micro-computed tomography (Micro-CT) techniques were employed to analyze the progressive mechanical properties and failure mechanism. Results showed that the matrix and interface have significant effects on the fracture toughness. Moreover, 2.5D woven composites with PyC/SiC interfacial layers and VHPCS matrix have the highest fracture toughness (16.93 +/- 1.20 Mpa center dot m(1/2)). Furthermore, during progressive damage, the pores can influence the crack expansion path, and effectively regulate the stress concentration and increase the toughness of the composites.

Automated summary

This paper investigates the effects of matrix and interface on the fracture toughness and progressive damage mechanisms of 2.5D woven SiCf/SiC composites. Different interfacial layers and matrix materials were used, and the fracture toughness was determined through single edge notch bending tests. Results showed that the matrix and interface significantly influence the fracture toughness, with the composite containing PyC/SiC interfacial layers and VHPCS matrix exhibiting the highest fracture toughness. Furthermore, the presence of pores during progressive damage was found to affect the crack expansion path and improve the toughness of the composites.