Fracture behaviour of SiC/SiC ceramic matrix composite at room temperature

Ceramic matrix composites are promising materials for structural applications at high temperature due to their excellent thermo-mechanical properties. Despite all their advantages, standardised methods for the characterisation of fracture toughness have not been established yet. Therefore, it is necessary to develop an understanding of their fracture behaviour. In this study, the fracture behaviour of silicon carbide (SiC) materials reinforced by SiC fibres is investigated using notched beams in flexural and tensile tests. The toughening mechanisms were identified. The work of fracture ranges between 4.0 and 24.6 kJ.m(-2) and the fracture toughness K-IC ranges between 3.2 and 5.5 MPa.m(1/2). An equivalent fracture toughness K-eq that reflects to some extent the degree of extrinsic toughening was defined and values range between 23.5 and 27.9 MPa.m(1/2). K-IC and the work of fracture decrease with increasing displacement rate while the strength was not affected. K-IC measurements reveal the material's anisotropy, higher values were obtained for the out-of-plane fibres orientation.

Automated summary

Ceramic matrix composites have excellent thermo-mechanical properties but lack standardized methods for characterizing fracture toughness. This study investigates the fracture behavior of silicon carbide materials reinforced by SiC fibers, identifying the toughening mechanisms and evaluating the fracture parameters.