Preparation of porous β-Si3N4/Si5AlON7 composite ceramics for digital light processing and study of mechanical and dielectric properties

Porous beta-Si3N4/Si5AlON7 composite ceramics are anticipated to serve as high-temperature wave-transparent materials, yet the fabrication of high-performance porous beta-Si3N4/Si5AlON7 composite ceramics remains a significant challenge. Addressing this issue, this study introduces a technique for crafting high-performance porous beta-Si3N4/Si5AlON7 composite ceramics. This method involves the homogeneous blending of SiO2 and Si3N4 powders, followed by digital light processing and high-temperature liquid-phase sintering at 2000 degrees C. The impact of SiO2 content on various properties of the ceramic slurry and the resultant ceramics was thoroughly examined, including rheology, curing depth, microstructural morphology, phase composition, flexural strength, hardness, dielectric constant, and dielectric loss. It was observed that a SiO2 content of 30 % enables the slurry to fulfill the criteria for digital light processing, leading to the production of porous beta-Si3N4/Si5AlON7 composite ceramics that exhibit outstanding mechanical and dielectric properties. Specifically, these ceramics demonstrated a flexural strength of 149.2 +/- 7.2 MPa and a hardness of 11.8 +/- 1.1 GPa. Moreover, at a frequency of 10 GHz, the ceramics exhibited a dielectric constant of 4.02 and a dielectric loss of 0.11, highlighting their potential as high-temperature wave-transparent materials.