抄録
ZrB2–SiC–ZrC (ZSZ) ternary composites of four differing compositions were fabricated by spark plasma sintering (SPS). The effect of the ZrB2/ZrC ratio on the oxidation behavior was examined by thermogravimetric (TG) analysis and microstructural observations. In addition, in-situ observation above 1500°C was performed using a high-temperature observation system (HTOS). ZSZ composites with high ZrC contents were fully oxidized at temperatures below 1500°C. However, ZSZ composites with low ZrC contents formed protective oxide layers during heat exposure. These layers protected the unreacted regions from further oxidation. Island nucleation was successfully observed on the surface oxide layer at 1500°C using the HTOS. The nucleation of islands strongly depended on the ZSZ composition. The difference in oxidation behavior originated from the concentration and interparticle distance of the ZrC in the as-sintered compacts.
