Abstract

ZrB_2-based composites are candidate materials for ultra-high temperature materials (UHTMs). ZrB_2 has become an indispensable ingredient in UHTMs, due to its high melting temperature, relatively low density, and excellent resistance to thermal shock or oxidation. ZrB_2 powders are usually synthesized by solid state reactions such as carbothermal, borothermal, or combined carbothermal reaction. SiC is added to this system in order to enhance the oxidation resistance of ZrB_2. In this study, ZrB_2?based composites were successfully synthesized and densified through two different processing paths. ZrB_2 or ZrB_2 25 vol.%SiC was fully synthesized from oxide starting materials with reducing agents after heat treatment at 1400°C. Besides, ZrB_2?20 vol.%SiC was fully densified with B_4C as a sintering additive after hot pressing at 1900°C. The synthesis mechanism and the effect of sintering additives on densification of ZrB_2 ?SiC composites were also discussed.

• Keywords: ZrB_2-SiC composites;UHTMs(Ultra-high temperature materials);Synthesis;Densification;Sintering additives;