HUANG Anqi, ZHU Shizhen, LIU Ling, MA Zhuang, GAO Lihong
(National Key Laboratory of Science and Technology on Materials under Shock and Impact,
Beijing Institute of Technology, Beijing 100081, China)

Abstract: SiC-TiB₂ multiphase ceramics were prepared with different content of TiB₂ by spark plasma sintering technique (SPS), using SiC as matrix, TiB₂ as secondary phase and YAG as sintering additive. The sintering temperature is 1700 °C and the sintering pressure is 50 MPa.The phase and microstructure of the samples were analyzed by XRD, SEM, TEM and EDS to illustrate the change of mechanical properties.The results show that SiC-TiB₂ multiphase ceramics sintered by SPS has fine grain with average grain size of 1μm. The adding of TiB₂ has a negative effect on the sintering of SiC-TiB₂. Because of the reaction between SiC and the thin oxygen rich layer (TiO₂) on the surface of TiB₂, TiC is induced. Meanwhile because of the abrasive nature of the TiB₂ powders, a small amount of the YSZ was picked up after milling.The adding of TiB₂ makes sintering additives incline to form amorphous phases and thus improving the bonding strength between grains.The flexure strength and fracture toughness of SiC-TiB₂ increase at first and then decrease with the increase of TiB₂. The maximum flexural strength of 662 MPa and the maximum fracture toughness of 8.84 MPa•m^1/2 were obtained by samples with 15%TiB₂.

Key words: SiC-TiB₂; SPS; flexural strength; fracture toughness