Fabrication and Characterization of ZrB2-Based Ceramic Using Synthesized ZrB2-LaB6Powder

ZrB2–LaB6 powder was obtained by reactive synthesis using ZrO2, La2O3, B4C, and carbon powders. Then ZrB2–20 vol% SiC–10 vol% LaB6 (ZSL) ceramics were prepared from commercially available SiC and the synthesized ZrB2–LaB6 powder via hot pressing at 2000°C. The phase composition, microstructure, and mechanical properties were characterized. Results showed that both LaB6 and SiC were uniformly distributed in the ZrB2 matrix. The hardness and bending strength of ZSL were 17.06±0.52 GPa and 505.8±17.9 MPa, respectively. Fracture toughness was 5.7±0.39 MPa·m1/2, which is significantly higher than that reported for ZrB2–20 vol% SiC ceramics, due to enhanced crack deflection and crack bridging near SiC particles.