Non-axially aligned ZrB2-SiC/ZrB2-SiC-graphene short fibrous monolithic ceramics with isotropic in-plane properties

Although axially aligned fibrous monolithic ceramics have superior mechanical properties in ceramic fiber axial direction, the obvious anisotropy in physical and chemical properties of fibrous monolithic ceramics predetermine the significant on-axis and off-axis discrepancy. The existing ZrB2-based fibrous monolithic ceramics were all arranged by axially aligned ceramic fibers. Non-axially aligned ZrB2-SiC/ZrB2-SiC-graphene short fibrous monolithic ceramics with isotropic in-plane properties were fabricated by hot pressing of disorderly arranged short ZrB2-SiC/ZrB2-SiC-graphene fibers to overcome in-plane anisotropy of the ZrB2-based fibrous monolithic ceramics. ZrB2-SiC/ZrB2-SiC-graphene short fibrous monolithic ceramics have remarkable increase in fracture toughness, critical crack size and work of fracture compared with ZrB2-SiC ceramics. The toughening mechanism of ZrB2-SiC/ZrB2-SiC-graphene short fibrous monolithic ceramics include macroscopic toughening of crack deflection, crack branching, interface friction and ZrB2-SiC cell extraction, and microscopic toughening of graphene bridging and pull-out.