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 degrees C. Due to the phase transformation of ZrO2, the toughness of ZrB2/ZrO2 FGCs was increased from similar to 5 MPa m(1/2) for the ZrB2-rich layer to similar to 10 MPa m(1/2) for the ZrO2-rich layer. The effect of sintering temperature on the toughness of ZrB2/ZrO2 FGCs was further investigated. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.