Preparation and properties of SiC_pl/ZrB₂ ultra-high temperature ceramics

Zirconium diboride (ZrB₂) based ceramics reinforced by silicon carbide platelet (SiC_pl) have been investigated. Using the hot pressing sintering method, high density SiC_pl/ZrB₂ composites were prepared at a sintering temperature of 1950°C for 1 h under 20 MPa pressure in an argon flow. The phase composition, microstructure and mechanical properties of the SiC_pl/ZrB₂ ceramic composites were researched by X-ray diffraction, scanning electron microscopy, three-point bending test and single-edge notched beam method. The results show that the relative density and toughness of the SiC_pl/ZrB₂ composites added with the increase of SiC_pl are improved greatly. When 15% (in volume) SiC_pl are added, the relative density of SiC_pl/ZrB₂ ceramic composites reach 99%, the toughness reachs (8.35+0.26) MPa·m^1/2, and the bending strength reachs (522 ± 49) MPa. The mechanical properties of SiC_pl/ZrB₂ composites with oriented arrangement of SiC_pl in the composites prepared by the rolled film method slightly descend.