Effect of TiO2 addition on the microstructures, mechanical and dielectric properties of porous Si3N4-based ceramics

Porous Si 3 N 4 -based ceramics with different TiO 2 contents were prepared by gas pressure sintering method. The effects of TiO 2 addition ranging from 0 to 25 wt-% on the phase compositions, microstructures, mechanical performance and dielectric properties were investigated. The addition of TiO 2 significantly promoted the density which increased from 1.64 to about 2.3 g cm −3 . The mechanical properties of porous Si 3 N 4 -based ceramics with TiO 2 addition decreased first and then increased with the increase of TiO 2 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 Si 3 N 4 ceramic without TiO 2 addition. With the increase of TiO 2 content, both the dielectric constant and dielectric loss increased, and the dielectric constant enhanced obviously. These results suggested that the TiO 2 was beneficial for the improvement of mechanical properties and dielectric constant of porous Si 3 N 4 -based ceramics.