Abstract
ZrB_2-SiC-ZrC(ZSZ) is known as one of ultra-high temperature ceramics (UHTCs) composite materials. In this study, four different composition of the ZSZ and ZrB_2-SiC were fabricated by spark plasma sintering. The specimens were oxidized at 1700℃ for 10 min in two different oxygen partial pressure. After the oxidation tests, SiO_2 and ZrO_2 were formed on the surface of both ZSZs and ZrB_2-SiC. In addition, unoxidized region still remained under these oxides. In case of the ZSZ, thickness of oxidized layer increased with ZrC volume content. After oxidation test under low oxygen partial pressure, porous layer was observed in the ZrB_2-SiC, but no such layer was observed in the ZSZs. Since the porous layer is brittle and low strength, the ZSZ has an advantage in the mechanical properties after oxidation. In order to validate the advantage of the ZSZ, the oxidation behavior was thermodynamically analyzed using volatility diagrams.
