Structure evolution of ZrB2-SiC during the oxidation in air

The structure evolution and oxidation behavior of ZrB2-SiC composites in air from room temperature to ultrahigh temperature were investigated using furnace testing, arc jet testing, and thermal gravimetric analysis (TGA). The oxide structure changed with the increasing temperature. SiC content has no apparent influence on the evolution of structure during the oxidation of ZrB2-SiC below 1600 degrees C. However, the evolution of structure for ZrB2-SiC above 1800 degrees C was significantly affected by the SiC content. The formation of the SiC depleted layer in the ZrB2-SiC system not only depends on the surrounding conditions of pressure and temperature but also on the structure distribution of the SiC in the ZrB2 matrix. The apparent recrystallization of the ZrO2 occurred above 1800 degrees C. The SiC content should be controlled at similar to 16% in the ZrB2-SiC system for the ultrahigh-temperature application. The mechanisms of the structure evolution during oxidation in air were also analyzed.