A novel development of ZrB2/ZrO2 functionally graded ceramics for ultrahigh-temperature application

ZrB2/ZrO2 functionally graded ceramics (FGCs), newly developed for ultrahigh-temperature application, were prepared by spark plasma sintering. Denser graded microstructure as well as a “strong” interface were achieved for ZrB2/ZrO2 FGC sintered at 1800 °C. Due to the phase transformation of ZrO2, the toughness of ZrB2/ZrO2 FGCs was increased from ∼5 MPa m1/2 for the ZrB2-rich layer to ∼10 MPa m1/2 for the ZrO2-rich layer. The effect of sintering temperature on the toughness of ZrB2/ZrO2 FGCs was further investigated.