Non-additive sintering of Si2N2O ceramic with enhanced high-temperature strength, oxidation resistance, and dielectric properties

The high-temperature mechanical and dielectric properties of Si2N2O ceramics are often limited by the introduction of a sintering aid. Herein, dense Si2N2O was prepared at 1700 degrees C by hot-pressing oxidized amorphous Si3N4 powder without sintering additives. A homogeneous network with short-range order and a SiN3O structure was formed in the oxidized amorphous Si3N4 powder during the hot-pressing process. Si2N2O crystals preferentially nucleated at positions within the SiN3O structure and grew into rod-like and plate-like grains. Fully dense ceramics with mainly crystalline Si2N2O and some residual amorphous phases were obtained. The as-prepared Si2N2O possessed a good flexural strength of 311 +/- 14.9 MPa at 1400 degrees C, oxidation resistance at 1500 degrees C, and a low dielectric loss tangent of less than 5 x 10(-3) at 1000 degrees C.

Automated summary

Dense Si2N2O ceramics were successfully prepared without sintering additives, exhibiting good flexural strength, oxidation resistance, and low dielectric loss tangent at high temperatures.