Understanding interfacial bonding properties and mechanical properties of in situ synthesis of Cf/ZrB2-ZrC-SiC composite

The relationship between the interfacial bonding properties and the mechanical properties of carbon fiber reinforced ZrB2-ZrC-SiC composites (Cf/ZrB2-ZrC-SiC) is currently under investigation. In this study, Cf/ZrB2-ZrC-SiC composites with varying fiber-matrix interfacial bonding properties were prepared using slurry infiltration and in-situ reactive hot pressing. Polydopamine-derived carbon with different thicknesses was employed as the interphase to create various interfacial bonding properties, where interfacial bonding properties were evaluated using the single-fiber push-out method. Results indicated that a uniform and dense ZrB2-ZrC-SiC matrix was constructed, and low-porosity composites without fiber degradation were obtained. For composites with a higher interfacial shear strength (ISS) of 342 MPa, flexural strength and fracture toughness were 209 MPa and 7.5 MPa<middle dot>m1/2, respectively. For composites with a lower ISS of 64 MPa, flexural strength and fracture toughness increased by 41% and 13%, with showing non-brittle behavior and work of fracture up to 10 kJ<middle dot>m2. By combining analyses of thermal expansion behavior, residual thermal stresses, and thermal shock properties at ultrahigh temperatures, thermal mismatch and thermal damage can be minimized through the modulation of ISS. This approach is beneficial for optimizing the mechanical properties of fiber-reinforced ceramic composites.