Mechanical and dielectric properties of Si3N4-SiO2 ceramics prepared by digital light processing based 3D printing and oxidation sintering

Si 3 N 4 -SiO 2 ceramics are considered as the preferred high-performance wave-transmitting material in the aerospace field. However, traditional fabrication methods for Si 3 N 4 -SiO 2 ceramics have the disadvantages of high cost and complicated fabrication process. In this paper, Si 3 N 4 -SiO 2 ceramics with excellent mechanical and dielectric properties were fabricated by digital light processing-based 3D printing combined with oxidation sintering. Firstly, the curing thickness and viscosity of slurries with different solid loadings for vat photopolymerization-based 3D printing were studied. Then, the effects of the sintering temperature on the linear shrinkage, phase composition, microstructure, flexural strength , and dielectric properties of Si 3 N 4 -SiO 2 ceramics, and the influences of solid loading on them were explored. The curing thickness and viscosity of the slurry with a solid loading of 55 vol% were 30 μm and ∼1.5 Pa‧s, respectively. The open porosity and the flexural strength of Si 3 N 4 -SiO 2 ceramic with a solid loading of 55 vol% were 4.3 ± 0.61% and 76 ± 5.6 MPa, respectively. In the electromagnetic wave band of 8–18 GHz, the dielectric constant of Si 3 N 4 -SiO 2 ceramics was within the range of less than 4, and the dielectric loss remained below 0.09. The method of digital light processing-based 3D printing combined with oxidation sintering can be further extended in the preparation of Si 3 N 4 -based structure-function integrated ceramics.