Fracture behavior of laminated ZrB 2 –SiC ceramics at high temperature in air

Abstract With BN and graphite as weak interfacial phases, ZrB 2 -SiC/BN (LZrB) and ZrB 2 -SiC/graphite (LZrG) laminated ceramics were prepared by tape casting and hot pressing. The fracture behaviors of the above two laminated ceramics were investigated at room temperature and high temperature. At room temperature, the flexural strengths of LZrB and LZrG ceramics were 381 ± 21 MPa and 414 ± 17 MPa, respectively. When heated at 1300 °C and 1500 °C, the flexural strength of LZrG ceramic was higher than that of the LZrB ceramic. When heated at 1500 °C for 2 h, flexural strength of the LZrG ceramic was as high as 352 MPa, suggesting typical multiple fractures. Such excellent high temperature flexural strength of LZrG ceramic was attributed to the healing of surface flaws by the glassy phase SiO 2 after oxidation, the viscous bridging of ZrO 2 and SiO 2 , as well as the transgranular fracture mode of ZrB 2 grains in ZrB 2 -SiC layers.