Mechanical and dielectric properties of Si3N4/β-SiAlON composite ceramics fabricated by vat photopolymerization 3D printing technology

Abstract

Vat photopolymerization 3D printing provides a novel approach for preparing broadband wave-transparent Si3N4/β-SiAlON composite ceramics. This paper oxidized raw powder to introduce low dielectric phases (SiO2) and overcome the low curing depth of α-Si3N4. The solid content of oxidized α-Si3N4 was increased to 50 vol% for the first time by modification with dispersant. The selected print thickness of 50 μm was the highest known for Si3N4 vat photopolymerization 3D printing, greatly improving printing efficiency. Finally, Si3N4/β-SiAlON composite ceramics were sintered in the range of 1600-1800 °C, and the mechanical and dielectric properties were systematically studied. The composite ceramics sintering at 1780 °C had a maximum bending strength of 236 ± 16 MPa, and the real permittivity was 4.83. At 1800 °C the porosity increased resulting in bending strength decreased to 109 ± 4 MPa, and the real permittivity to 3.23. This study filled the gap in the post-treatment of oxidized α-Si3N4 and guided the application of Si3N4/β-SiAlON composite ceramics in the field of wave-transparent.