Influences of milling on the dielectric and microwave absorption properties of Ti₃SiC₂/cordierite composite ceramics

Cordierite ceramics doped with Ti₃SiC₂ powders milled for different time are fabricated by hot pressed sintering process. For the Ti₃SiC₂ powders, the particle size is decreased and the morphology is changed from lamellar to flaky with the increasing milling time. The finer Ti₃SiC₂ particles are detrimental to the densification process but favorable to the improvement of flexural strength of the full dense ceramics. Dielectric and microwave absorption properties of the ceramics are investigated in the frequency range of 8.2-12.4 GHz. As the milling time increases, both the real and imaginary part of the complex permittivity are enhanced which is attributed to the decrease of particle size and formation of flaky particles. The ceramic doped with Ti₃SiC₂ powders milled for 10 h presents the optimal microwave absorption property. The effective absorption bandwidth (RL < -10 dB) with a minimal R_L value of -16.4 dB is obtained in 9.7-12.4 GHz for the ceramic in 1.6 mm thickness.