Fabrication of Si_3N_4-SiBC composite ceramic and its excellent electromagnetic properties

摘要

To obtain better electromagnetic wave absorbing property, it is vitally necessary to develop novel ceramics with not only high dielectric loss but also low dielectric constant. Si_3N_4-SiBC, a composite ceramic with such dielectric properties, was fabricated by infiltrating SiBC into porous Si_3N_4 ceramic via low pressure chemical vapor infiltration. The high dielectric loss and the low dielectric constant are attributed to the unique microstructure of SiBC, which also leads to a very excellent wave-absorbing property of Si_3N_4-SiBC ceramic, attaining a minimal reflection coefficient of -28 dB. Besides, the Si_3N_4-SiBC ceramic also shows a high mechanical property. Therefore, the Si_3N_4-SiBC ceramic exhibits great potential as an excellent functional and structural ceramic.