Effect of TiO ₂ addition on the microstructures, mechanical and dielectric properties of porous Si ₃ N ₄ -based ceramics

Porous Si3N4-based ceramics with different TiO2 contents were prepared by gas pressure sintering method. The effects of TiO2 addition ranging from 0 to 25 wt-% on the phase compositions, microstructures, mechanical performance and dielectric properties were investigated. The addition of TiO2 significantly promoted the density which increased from 1.64 to about 2.3 g cm−3. The mechanical properties of porous Si3N4-based ceramics with TiO2 addition decreased first and then increased with the increase of TiO2 content, and the flexural strength and elastic modulus are more than 167.4 MPa and 72.8 GPa, respectively, which were higher than that of the Si3N4 ceramic without TiO2 addition. With the increase of TiO2 content, both the dielectric constant and dielectric loss increased, and the dielectric constant enhanced obviously. These results suggested that the TiO2 was beneficial for the improvement of mechanical properties and dielectric constant of porous Si3N4-based ceramics.