Mechanical, Dielectric, and Microwave-Absorption Properties of Alumina Ceramic Containing Dispersed Ti₃SiC₂

Dense Al₂O₃ ceramics containing dispersed Ti₃SiC₂ were fabricated by hot-pressed sintering. Effects of Ti₃SiC₂ content on the mechanical, dielectric, and microwave-absorption properties of the ceramics were investigated. The bulk density, flexural strength, and dielectric constant were enhanced by increasing the Ti₃SiC₂ content. The complex permittivity increased dramatically when the Ti₃SiC₂ content was above the percolation threshold. The dielectric performance of the ceramics at high temperatures was also studied. The results revealed increases in both the real and imaginary parts with increasing temperature. Ceramic 2.2 mm thick containing 10% (w/w) Ti₃SiC₂ had the optimum microwave-absorption properties. The absorption bandwidth below −5 dB was in the range 8.2–12.4 GHz with a minimum value of −20 dB at 9.56 GHz. Although the reflection loss increased with the increasing temperature, the ceramic still had favorable microwave-absorption properties throughout the X-band. This study contributes to the development of the microwave absorption materials for high-temperature application.