Oxidation behavior of ZrB2-xSiC composites at 1500 °C under different oxygen partial pressures

The oxidation behavior of zirconium boride composites with various SiC contents (0–40 vol%) at 1500 °C in air (pO2= 104 Pa) and under low pO2 (10–8 Pa) was investigated. Due to different oxidation kinetics calculated from the oxidation depths, the oxidized composites exhibited different layered structures. In addition, the composites of ZrB2-30 vol% SiC (one of the typical compositions) oxidized at 1500 °C for 10 h in air and under low pO2 conditions were analyzed using TEM (transmission electron microscope). In air, the oxidation depth as a function of time indicated a parabolic kinetic behavior, and the ZrB2-40 vol% SiC composite exhibited the lowest parabolic rate constant (kP) of 232 μm2/h. Under low pO2, the oxidation depth as a function of time indicated a parabolic to linear transition kinetic behavior, except for monolithic ZrB2. The monolithic ZrB2 exhibited the lowest parabolic rate constant (kP) of 811 μm 2/h.