Improved tensile strength and toughness of dense C/SiC-SiBC with tailored PyC interphase

In this study, in order to improve the tensile strength and toughness of dense C/SiC-SiBC, the thickness of PyC interphase (e(pyc)) was increased from 200 nm to 400 nm. C/SiC (e(pyc) approximate to 200 nm) was also fabricated as a benchmark comparison. C/SiC-SiBC (e(pyc) approximate to 200 nm) exhibited higher axial thermal residual stress (TRS) than C/ SiC (e(pyc) approximate to 200 nm). Increased axial TRS resulted in increased interfacial shear strength CO through fiber bending, which caused lowered mechanical properties of C/SiC-SiBC (e(pyc) approximate to 200 nm). By increasing the thickness of PyC interphase from 200 nm to 400 nm, the axial TRS in C/SiC-SiBC decreased. Accordingly, the radial stress induced by fiber bending decreased, leading to a reduced r in C/SiC-SiBC (e(pyc) approximate to 400 nm). Decreased axial TRS and r are beneficial to the effective loading of fiber bundles and pull out of fibers. Therefore, C/SiC-SiBC (e(pyc) approximate to 400 nm) performed excellent tensile strength (250 +/- 11 MPa) and fracture toughness (23.7 0.5 mpa.m1/2).