Dielectric and microwave absorption properties of Ti₃SiC₂/cordierite composite ceramics oxidized at high temperature

The oxidation behavior of the bulk Ti₃SiC₂/cordierite composite ceramics containing 15 wt.% Ti₃SiC₂ are investigated in air. The results demonstrate the ceramic displays excellent oxidation resistance at 800-1000 °C, and the oxidation kinetics basically obey a parabolic rate law. As revealed by XRD and SEM/EDS, the oxidation scales mainly consist of rutile TiO₂ and amorphous SiO₂. The dielectric and microwave absorption properties of the ceramics oxidized at high temperature are also studied. Both the real and imaginary part of the complex permittivity are decreased as the oxidation temperature increases from 800 to 1000 °C, which is attributed to the oxidation of Ti₃SiC₂ fillers close to the surface. At a given temperature, the complex permittivity decreases at the initial oxidation stage while it keeps stable as the oxidation time increases. Although the complex permittivity of the ceramics are decreased after oxidation at high temperature, the microwave absorption performances are still favorable. The results indicate the Ti₃SiC₂/cordierite ceramics are potential microwave absorption materials for high temperature application.