LIU Lanyong, WEI Chuncheng, DUAN Xianghan, MA Xuefei, ZHANG Zhongya

(School of Materials Science and Engineering, Shandong University of Technology, Zibo 255000, Shandong, China)

Abstract: ZrB₂ based ultra-high temperature ceramics are structural materials with high oxidation, ablation and temperature resistances. They have a wide range of applications in aerospace and other fields, but their applications are limited by their brittleness. In recent years, layered ceramics showed special crack propagation characteristics, which is considered to be an effective way to increase toughness of ceramics. Laminated ZrB₂-SiC/SiCw ultra-high temperature ceramics were prepared by using tape casting and hot pressing. Oxidation behavior of the laminated ceramics at 1500 ℃ was studied. The effects of oxidation time on residual strength and weight gain were examined, while the phase composition and morphology were analyzed. Bending strength of the laminated ZrB₂-SiC/SiCw ultra-high temperature ceramics is 607 MPa and the fracture toughness is 12.5 MPa·m ^1/2 at room temperature. After oxidation for 10 h, the bending strength is still 510 MPa and the fracture toughness is 7.8 MPa·m ^1/2. It is ascribed to the formation of dense SiO₂ glass layer on the surface, which prevented the internal oxidation of the materials.

Key words: ZrB2; laminated; oxidation; residual strength