Fracture toughness and toughening mechanisms in a (ZrB2–SiC) composite reinforced with boron nitride nanotubes and boron nitride nanoplatelets

A ZrB2–SiC composite reinforced with the mixture of boron nitride nanotubes (BNNTs) and boron nitride nanoplatelets (BNNPs) was prepared by spark plasma sintering. The results show that the fracture toughness of a (ZrB2–SiC) composite increases by up to ∼24.4% at 1.0% (BNNT–BNNP) weight fraction. The synergetic toughening mechanisms, including BNNT and BNNP pullout, crack bridging by BNNP, crack branching and crack deflection, and bending of multilayered BNNPs, are observed to contribute to the improved toughness.